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Austenite reversion in cold formed 18 vvt-Ni 350 grademaraging steelA Ali M Ahmed F H Hashmi and A Q Khan

Austenite reversion as afunction of deformation processes has been investigated in an 18 wt-Ni 350 grade maraging steel Theresults reported show that the degree and type of deformation imparted to martensite influences the amount of reverted austeniteobtained following aging The validity of the X -ray diffraction technique in determining the reverted austenite content isdiscussed with reference to texture incorporated during cold forming Transmission electron microscopy was carried out to studythe partitioning of solute during austenite reversion MSTj 1842

copy 1994 The Institute of Materials Manuscript received 28 January 1993 infinalform 13 May 1993 The authors are at theDr A Q Khan Research Laboratories Rawalpindi Pakistan

specimens were deformed by either cold rolling or flowturning Specimens of size lOx 10 mm were cut from thedeformed sheets for heat treatment and subsequentdetermination of austenite content

Thin foils were obtained from the heat treated specimensand were examined in a Jeol2000FX scanning transmissionelectron microscope equipped with an energy dispersiveX-ray (EDX) spectrometer to facilitate chemical analysis

DETERMINATION OF AUSTENITEThe X-ray diffraction method of quantitative phase analysiswas applied to determine the volume percentage of revertedaustenite (a) The direct comparison method of Averbachand Cohen9 was employed which does not require astandard sample of known austenite content because therequired reference line is obtained from the martensite (m)The basic equation relating the diffracted intensity andvolume fraction of austenite Jt in an alloy containing onlyaustenite and marfensite of the same chemical compositionis as follows10

Jt = volume fraction of austenitela 1m= integrated intensity of martensite and

austenite respectively measured from X-rayspectrum

Ra Rm = theoretical peak intensities of austenite andmartensite respectively which in turn dependon hkl Bragg angle 8 structure factor FLorentz polarisation L volume of unit cell vmultiplicity factor p and temperature factorexp(-2M)

Xray peaks from a deformed specimen containing revertedaustenite were observed at IIIL IIOm 200a 200m220a and 220m planes (Fig 2) Thus when R factors arecalculated for these planes the volume fraction of austenitecan be calculated from equation (1) These R values werecalculated for 18Ni 350 maraging steel The equation for

Introduction

Maraging steels are highly ductile in martensitic form Thefinal shape of the components can be readily achieved byrolling forging or flow turning An aging treatmentfollowing mechanical working is employed to achieve theoptimum strength The optimum aging temperatures for18Ni 350 grade maraging steels are in the range480-5IOdegC (Ref 1) It is also well established that deform-ation of martensite (marforming) before aging can increasestrength by up to 1500 depending upon the amount ofdeformation2-4 When electrical and magnetic propertiesare of interest maraging steels are aged in the temperaturerange 550-650degC This treatment results in the formationof austenite that remains stable at room temperature5 Thedissolution of precipitates and formation of the austenitephase are the main causes of the softening observed athigher aging temperatures6 They also play a significantrole in fatigue and stress corrosion cracking67

A substantial amount of work has been carried out onthe phase changes that result in the formation of stableaustenite However very little work has been reported onthe influence of deformation processes on the subsequentaustenite reversion Cairns8 studied the effect of drawingon reversion characteristics of different grades of maragingsteel and concluded that increasing the amount of priordeformation decreases the range of aging temperatures forwhich stable austenite is retained in the microstructure atroom temperature Floreen and Decker1 reported thatplastic deformation before aging increases the amount ofreverted austenite formed

The purpose of the present work is to study the formationof austenite in cold worked 18Ni 350 grade maragingsteel Texture incorporated during cold working has apronounced influence on the relative intensities of X-raypeaks for both austenite and martensite phases A methodfor determining the austenite content obtained followingaging in deformed specimens has been discussed andapplied to the experimental data With regard to quantifi-cation of austenite in textured specimens appropriate peaksthat give reasonable results are discussed

(R I )-1Jt= I+-2~Rm Ia

where

(1)

Experimental

The chemical composition of the 18Ni 350 grademaraging steel used in the present study is given in Table 1All the specimens were first annealed at 820degC for 1 h in avacuum furnace and air cooled to room temperature The

Table 1 Chemical composition of 18Ni 350 grademaraging steel used in present studywt-

C Si Mo Ni AI Co Ti Fe

lt0middot01 0middot08 4middot16 17middot80 0middot08 12middot32 1middot70 Bal

Materials Science and Technology February 1994 Vol 10 97

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98 Ali et al Austenite reversion in cold formed maraging steel

Annealed(211)m

50 60 70 80 90

28 (deg)

X-ray spectra obtained from annealed (1 h at 820degC)flow formed and cold rolled specimens of maragingsteel 18 wt-OoNi 350 grade (FF40 FF57 and FF77denote flow forming to reductions of 40 57 and7700 respectively and CR50 denotes cold rolling to50deg0 reduction)

60 70 80

28 (deg)

2 X-ray spectra showing influence ofaustenite and martensite peaks afteraging at 680degC for 1 h

Results and discussion

90

texture onsubsequent

(2)

R is given in Ref 10 as

1R = 2 F2p(L) exp(- 2M)

vThe factors in this equation were assigned values suggestedby Cullityl0-12 The unit cell volume was calculated fromthe measured lattice parameters of martensite and austenitein the present alloy The other parameters required aregiven in Table 2

The volume percentage of austenite that formed byreversion of the martensite during aging was determinedfrom the relative intensities of the Ill 220 and 200austenite and the II a 200 and 211 martensite X-raydiffraction peaks The aforementioned scattering factors ofthe two phases are assumed to be identical The integratedintensity of the peaks was taken to be the product of thepeak height and width at half maximum The volumefraction of the precipitate is unknown and the values ofaustenite volume fraction reported in this work are thereforesomewhat high The specimens were irradiated using nickelfiltered Cu Krx radiation

The presence of retained austenite is known to have apronounced influence on austenite reversion during sub-sequent aging treatment2 In addition it has been reportedthat austenite can also form during machining13 All thespecimens were examined after annealing and subsequentcold working to determine whether any retained austenitewas present before heat treatment The X-ray diffractograms(Fig I) showed distinctly that no austenite peaks werepresent in the as deformed specimens

DETERMINATION OF AUSTENITE INDEFORMED SPECIMENSThe direct comparison method is based upon the assump-tion that the diffracting specimen is homogeneous andrandomly oriented and as such the diffraction peakintensities vary only as a result of the volume fraction ofthe phases present and not as a result of preferredorientation or texture When applied to specimens that doincorporate texture such as rolled sheets significant errormay result from the variation in the integrated diffracted

Table 2 Values required for calculation of R for 18 wt-Ni 350 grade maraging steel

Planes Cia nm 1jv2 nm-6 e deg f nm-1 L deg F2 p exp(-2M) R

110m 0middot28636 1middot81 X 103 22middot37 185middot2 11middot23 1371middot96 12 0middot954 319middot25200m 32middot55 152middot3 4middot82 927middot81 6 0middot91 44middot39211m 41middot15 130middot8 3middot12 684middot34 24 0middot87 81middot34111 a 0middot35809 4middot74 X 102 21middot90 186middot8 11middot78 5583middot07 8 0middot955 238middot32200a 25middot50 173middot8 8middot34 4833middot03 6 0middot936 107middot29220a 37-48 138middot4 363 3064middot73 24 0middot900 113middot90

c(o lattice parameter v volume of unit cell e Bragg angle f atomic scattering factor L Lorentz polarisation factor F structure factor dependingupon type of crystal p multiplicity factor calculated from table of Ref 11 exp (- 2M) temperature factor calculated from graph of Ref 12R peak intensity

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Ali et al Austenite reversion in cold formed maraging steel 99

60FF77 200m200a

50 + FF87 200m200a

CR50 200m200a

40 30

Line of unit slope---- +20

+ +10(a)

O

60 x

FF40 ZII mZZOa

50 + FF57 ZllmZZOa FF77 Zllm2Z0a

0 +40 0 FF87 211m220a

tUX0 CR50 211m220a

CI t~ 30

~ 20

10 +---Line of unit slope (b)

00 10 20 30 40 50 60110m111a

3 Comparison of austenite volume fractions measuredusing a 110m111a and 200m200a andb110m111a and 211m220a peaks

50

40

~ 30Q)~cQ)~tn 20lt

10

070

60

50 Jr

~ lt7

(1) 40~c(1) 30-U)lt 20

10

(a)

- FF40

+ FF67

FF77

o FF87

--- Annealed

(b)

Annealed

- CR50-J CR85 ~

peak intensities of different peaks Such an effect isdemonstrable for cold formed maraging steel

Figure 1 shows the X-ray spectra obtained from annealedflow formed (FF) and cold rolled (CR) specimens Therelative peak intensities from an annealed specimen corre-spond to values that are expected for a hom~ge~eous ~~dequiaxed specimen of maraging steel The relatIve IntensItIesstart to change when reduction ratios above 50 areemployed for flow formed material This effect becomesmuch more pronounced after 75 reduction The llOmand 2llm peaks are most severely affected A similartendency was observed in specimens subjected to cldrolling Specimens cold rolled beyond 25 reductIonstarted to show this effect At 50 reduction the spectrumintensities appeared similar to those for the flow formedmaterial after 75 reduction Detailed texture analysis wasnot carried out in this investigation However the changein relative peak intensities is undoubtedly due to textureincorporated during flow forming and rolling10

The texture incorporated during cold working influencesthe austenite peaks obtained following aging Figure 2shows spectra obtained from annealed flow formed andcold worked specimens after subsequent aging at 680degC ~or1 h In the annealed specimen the expected llla austenItepeak is pronounced In deformed specimens however ~hellla austenite peak is obviously affected by deformatIontexture At reduction ratios above 25 200a and 220a austenite peaks appear and the lll L peak intensitydecreases It is also obvious from the spectra of flow formedspecimens that the relati~e inten~ities of allstenite ~eaksincreased with deformatIon ratIo sIgnIfYIng a hIgherpercentage of reverted austenite In cold rolled specimessimilar texture effects were observed the 220a austenItepeak being most prominent

In calculating the volume fractIon of austenIte textureeffects can be overcome by averaging the austenite contentscalculated from all the austenite peaks Measuring all thelines and averaging in the prescribed manner will yieldvalid data In the literature10 this method has been termedthe intensity averaging technique The basic concept in

o600 620 640 660 680 700 720 740

Temperature (0 C)4 Effect of reaustenitisation temperature on volume

fraction of austenite in a flow formed and b coldrolled specimens

the intensity averaging technique is simple if certain linesfrom the austenite phase are abnormally weak because oftexture the other austenite lines will be abnormallystrong (Fig 2)

If the intensity averaging of all the peaks is not carriedout considerable errors may result as is demonstratedbelow The volume fraction of austenite measured usingtwo possible selections of peaks is plotted in Fig 3 InFig3a austenite content is calculated from l1lalIOmand compared with 200a200m whereas in Fig 3baustenite content is measured by comparing lllallOmwith 220a2llm peaks Figure 3 shows variable corre-lation and a large scatter in the austenite content Aselected combination of peaks should not be used incalculating the volume fraction of austenite in texturedspecimens As mentioned above it is more appropriate tocalculate the austenite content in textured specimens byaveraging the austenite contents obtained from all thepeaks ie lllallOm 200a200m and 220L2llmpeaks The volume percentage of aus~enite presented inthis work was calculated USIng the IntenSIty averagIngtechnique

EFFECT OF DEFORMATION ONREAUSTENITISATIONThe amount of austenite formed following aging dependsnot only on the temperature but also on the type and degreeof deformation The amounts of austenite formed at varioustemperatures for different degrees of deformatio i~partedby flow forming and cold rolling are presented In FIg 4 Itis evident that for aging temperatures up to 680degC thereverted austenite content for a particular aging temperaturegenerally increases with degree of deformation In contrast

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100 Ali et al Austenite reversion in cold formed maraging steel

5 Specimen aged at 620degC for 1 h showing growth ofaustenite along martensite lath boundaries (TEM)

6 Specimen aged at 680degC for 1 h showingrecrystallisation of martensite in present maragingsteel (TEM)

Table 3 Chemical composition of austenite formed inspecimen transformed at 650degC for 1 h wt-

at aging temperatures above 680degC the cold worked speci-mens show a lower volume percentage of reverted austenitein comparison with the annealed specimens

Similar results were obtained in specimens that weresubjected to cold rolling before austenitisation In thesespecimens 50-70 more reverted austenite was notedin comparison with the annealed material for agingtemperatures up to 680degC as shown in Fig 4b

The details regarding the mechanism through which thereversion of austenite occurs have been the subject of manyinvestigations1261415 It is fairly well established that inthe initial stages austenite usually forms as long thinplatelets on the martensite lath boundaries Increasing thearea of these boundaries through flow forming or rollingprobably increases the amount of austenite that formsfollowing aging The excessive defect density incorporatedduring cold forming aids by providing a much finerdistribution of precipitates that form and subsequentlydissolve to give nickel rich regions along the lathboundaries and within the laths The microstructural detailsof austenite reversion in 18Ni 350 maraging steel havebeen investigated and will be presented elsewhere16 Onlythe relevant information is given in the present paper Atransmission electron micrograph (TEM) obtained from aspecimen aged at 620degC for 1 h is shown in Fig 5 Thespecimen was subjected to cold rolling (50 reduction)before aging The austenite phase can be seen mostly alongthe lath boundaries This austenite was analysed using theEDX facility and the composition determined by averaging10 readings is given in Table 3

It is evident that substantial partitioning of alloyingelements must occur before the austenite phase becomesstable at room temperature The cold working by virtueof the excess defect density introduced initiates theprecipitation reaction at lower temperatures and thereaction proceeds at a much more rapid rate comparedwith that of the annealed specimens On subsequent agingthe finer distribution of precipitates results in relativelyrapid dissolution and a higher volume fraction of austeniteis obtained

The relatively rapid redissolution of austenite at highertemperatures can be explained using the same reasoning

Si

0middot08

Mo

5middot0

Ni

28middot0

Co

8middot0

Ti

0middot8

Fe

Bal

The refined microstructure and higher defect densitydecrease the recrystallisation temperature and rapid dissolu-tion occurs Figure 6 is a TEM from a specimen subjectedto aging for 1 h at 680degC Recrystallisation has taken placeresulting in redissolution of nickel and thereby renderingthe martensite phase stable at room temperature

Conclusions

Austenite reversion in deformed 18wt-Ni 350 grademaraging steel was investigated In textured specimensaustenite peaks were affected by the deformation processesand the reverted austenite content is more accuratelyquantified by averaging all the peaks The deformation ofmartensite also influences the volume fractions of revertedaustenite The increase in austenite content depends stronglyupon the amount and type of deformation

Acknowledgements

The authors are indebted to Mr T N Siddiqui andMr M Irfan for their assistance in conducting X-raydiffraction studies and Mr M Khalid and Mr T Mehmoodfor assistance with metallography and photography

References

1 S FLOREEN and R F DECKER in Source book on maragingsteels (ed R F Decker) 20-32 1979 Metals Park OR ASM

2 M SCHMIDT and K ROHRBACH in Metals handbook Vol 4219-228 1991 Materials Park OR ASM

3 R F DECKER J T EASH and A J GOLDMAN Trans ASM 19625558-76

4 K DETERT Trans ASM 1966 59 262-2765 M AHMED M FAROOQ F H HASHMI S W HUSSAIN and

A Q KHAN in Proc Conf Maraging steels recent develop-ments and applications (ed R K Wilson) 269-282 1988Warrendale PA TMS-AIME

6 D T PETERS in Source book on maraging steels (edR F Decker) 304-316 1979 Metals Park OR ASM

7 R A COVERT and E P SADOWSKI in Proc 22nd Annual NACEConfMiami Beach FL April 1966 National Association ofCorrosion Engineers

8 R L CAIRNS Trans ASM 1969 62 244-256

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9 B L AVERBACH and M COHEN Trans AIME 194817640110 B D CULLITY in Elements of X-ray diffraction 2 edn 411

1978 Reading MA Addison-Wesley11 B D CULLITY in Elements of X-ray diffraction 2 edn 523

1978 Reading MA Addison-Wesley12 B D CULLITY in Elements of X-ray diffraction 2 edn 136

1978 Reading MA Addison-Wesley13 F HABIBY T N SIDDIQUI H HUSSAIN M A KHAN A ul HAQ

and A Q KHAN Mater Sci Eng 1992 A159 261-265

Ali et al Austenite reversion in cold formed maraging steel 101

14 v K VASUDEVAN V K KIM and c M WAYMAN Metall Trans1990 21A 2655-2668

15 D T PETERS and c R CUPP in Source book on maragingsteels (ed R F Decker) 317-325 1979 Metals ParkOR ASM

16 M AHMED unpublished work Dr A Q Khan ResearchLaboratories Rawalpindi Pakistan 1993

Phase Diagrams and MicrostructureA Computer-Aided Learning GuideJohn Pilling

Known as PHAUST this computer software package is a teaching tool which illustrates thedynamics of microstructural evolution during the solidification of metals and its relationship with theappropriate phase diagrams The accompanying user manual acts as a study guide whichillustrates howto solve problems using PHAUST as well as describing the underlying metho~ologiesemployed by PHAUST to solve microstructural - phase diagram related problems

PHAUST operates through a graphical user interface allowing users to select for study only thoseareas which are of interest or appropriate difficulty rather than wade through all the examples as intraditional programmed learning Users can select a phase diagram from the database thataccompanies the programme or create their own using simple point and click drawing Users thengenerate the starting point for the problem effectively allowing an infinite number of problems andwith on-line help an infinite number of worked examples

Contents Hardware Requirements

This package runs on IBM compatible PCsrUnning MS-DOS with a minimum of 640KbRAM It requires a mouse and EGA graphics

Operation Creating Your Own Diagrams An Introduction to Binary Phase Diagrams Equilibrium Solidification Scheil Equation Suggested Further Reading andBibliography

A database of binary phase diagrams for AI- CU- Ni-base alloys Au Pb Sn Sb alloys and someceramic and geological systems and a microstructural database including common precipitatesmorphologies faceting and non-faceting eutectics is also included with the software

Order Code PD524 Disk 1 x 3511 Manual 100pp spiral bound ISBN 0901716 11 1pound9600 (incl VAT) US$19200Extra copies of the manual are available pound1500 US$3000

Orders with remittance to The Institute of Materials Sales amp Marketing Dept 1 Carlton HouseTerrace London SW1Y 50B Tel (071) 976 1338 Fax (071) 839 2078Orders originating in Canada and the United States should be sent direct to Ashgate PublishingCo Old Post Road Brookfield VT 05036 USA Tel (802) 276 3162 Fax (802)276 3837Carriage UK customers please add pound250 per order (incl VAT) overseas customers addUS$600

Materials Science and Technology February 1994 Vol 10

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98 Ali et al Austenite reversion in cold formed maraging steel

Annealed(211)m

50 60 70 80 90

28 (deg)

X-ray spectra obtained from annealed (1 h at 820degC)flow formed and cold rolled specimens of maragingsteel 18 wt-OoNi 350 grade (FF40 FF57 and FF77denote flow forming to reductions of 40 57 and7700 respectively and CR50 denotes cold rolling to50deg0 reduction)

60 70 80

28 (deg)

2 X-ray spectra showing influence ofaustenite and martensite peaks afteraging at 680degC for 1 h

Results and discussion

90

texture onsubsequent

(2)

R is given in Ref 10 as

1R = 2 F2p(L) exp(- 2M)

vThe factors in this equation were assigned values suggestedby Cullityl0-12 The unit cell volume was calculated fromthe measured lattice parameters of martensite and austenitein the present alloy The other parameters required aregiven in Table 2

The volume percentage of austenite that formed byreversion of the martensite during aging was determinedfrom the relative intensities of the Ill 220 and 200austenite and the II a 200 and 211 martensite X-raydiffraction peaks The aforementioned scattering factors ofthe two phases are assumed to be identical The integratedintensity of the peaks was taken to be the product of thepeak height and width at half maximum The volumefraction of the precipitate is unknown and the values ofaustenite volume fraction reported in this work are thereforesomewhat high The specimens were irradiated using nickelfiltered Cu Krx radiation

The presence of retained austenite is known to have apronounced influence on austenite reversion during sub-sequent aging treatment2 In addition it has been reportedthat austenite can also form during machining13 All thespecimens were examined after annealing and subsequentcold working to determine whether any retained austenitewas present before heat treatment The X-ray diffractograms(Fig I) showed distinctly that no austenite peaks werepresent in the as deformed specimens

DETERMINATION OF AUSTENITE INDEFORMED SPECIMENSThe direct comparison method is based upon the assump-tion that the diffracting specimen is homogeneous andrandomly oriented and as such the diffraction peakintensities vary only as a result of the volume fraction ofthe phases present and not as a result of preferredorientation or texture When applied to specimens that doincorporate texture such as rolled sheets significant errormay result from the variation in the integrated diffracted

Table 2 Values required for calculation of R for 18 wt-Ni 350 grade maraging steel

Planes Cia nm 1jv2 nm-6 e deg f nm-1 L deg F2 p exp(-2M) R

110m 0middot28636 1middot81 X 103 22middot37 185middot2 11middot23 1371middot96 12 0middot954 319middot25200m 32middot55 152middot3 4middot82 927middot81 6 0middot91 44middot39211m 41middot15 130middot8 3middot12 684middot34 24 0middot87 81middot34111 a 0middot35809 4middot74 X 102 21middot90 186middot8 11middot78 5583middot07 8 0middot955 238middot32200a 25middot50 173middot8 8middot34 4833middot03 6 0middot936 107middot29220a 37-48 138middot4 363 3064middot73 24 0middot900 113middot90

c(o lattice parameter v volume of unit cell e Bragg angle f atomic scattering factor L Lorentz polarisation factor F structure factor dependingupon type of crystal p multiplicity factor calculated from table of Ref 11 exp (- 2M) temperature factor calculated from graph of Ref 12R peak intensity

Materials Science and Technology February 1994 Vol 10

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Ali et al Austenite reversion in cold formed maraging steel 99

60FF77 200m200a

50 + FF87 200m200a

CR50 200m200a

40 30

Line of unit slope---- +20

+ +10(a)

O

60 x

FF40 ZII mZZOa

50 + FF57 ZllmZZOa FF77 Zllm2Z0a

0 +40 0 FF87 211m220a

tUX0 CR50 211m220a

CI t~ 30

~ 20

10 +---Line of unit slope (b)

00 10 20 30 40 50 60110m111a

3 Comparison of austenite volume fractions measuredusing a 110m111a and 200m200a andb110m111a and 211m220a peaks

50

40

~ 30Q)~cQ)~tn 20lt

10

070

60

50 Jr

~ lt7

(1) 40~c(1) 30-U)lt 20

10

(a)

- FF40

+ FF67

FF77

o FF87

--- Annealed

(b)

Annealed

- CR50-J CR85 ~

peak intensities of different peaks Such an effect isdemonstrable for cold formed maraging steel

Figure 1 shows the X-ray spectra obtained from annealedflow formed (FF) and cold rolled (CR) specimens Therelative peak intensities from an annealed specimen corre-spond to values that are expected for a hom~ge~eous ~~dequiaxed specimen of maraging steel The relatIve IntensItIesstart to change when reduction ratios above 50 areemployed for flow formed material This effect becomesmuch more pronounced after 75 reduction The llOmand 2llm peaks are most severely affected A similartendency was observed in specimens subjected to cldrolling Specimens cold rolled beyond 25 reductIonstarted to show this effect At 50 reduction the spectrumintensities appeared similar to those for the flow formedmaterial after 75 reduction Detailed texture analysis wasnot carried out in this investigation However the changein relative peak intensities is undoubtedly due to textureincorporated during flow forming and rolling10

The texture incorporated during cold working influencesthe austenite peaks obtained following aging Figure 2shows spectra obtained from annealed flow formed andcold worked specimens after subsequent aging at 680degC ~or1 h In the annealed specimen the expected llla austenItepeak is pronounced In deformed specimens however ~hellla austenite peak is obviously affected by deformatIontexture At reduction ratios above 25 200a and 220a austenite peaks appear and the lll L peak intensitydecreases It is also obvious from the spectra of flow formedspecimens that the relati~e inten~ities of allstenite ~eaksincreased with deformatIon ratIo sIgnIfYIng a hIgherpercentage of reverted austenite In cold rolled specimessimilar texture effects were observed the 220a austenItepeak being most prominent

In calculating the volume fractIon of austenIte textureeffects can be overcome by averaging the austenite contentscalculated from all the austenite peaks Measuring all thelines and averaging in the prescribed manner will yieldvalid data In the literature10 this method has been termedthe intensity averaging technique The basic concept in

o600 620 640 660 680 700 720 740

Temperature (0 C)4 Effect of reaustenitisation temperature on volume

fraction of austenite in a flow formed and b coldrolled specimens

the intensity averaging technique is simple if certain linesfrom the austenite phase are abnormally weak because oftexture the other austenite lines will be abnormallystrong (Fig 2)

If the intensity averaging of all the peaks is not carriedout considerable errors may result as is demonstratedbelow The volume fraction of austenite measured usingtwo possible selections of peaks is plotted in Fig 3 InFig3a austenite content is calculated from l1lalIOmand compared with 200a200m whereas in Fig 3baustenite content is measured by comparing lllallOmwith 220a2llm peaks Figure 3 shows variable corre-lation and a large scatter in the austenite content Aselected combination of peaks should not be used incalculating the volume fraction of austenite in texturedspecimens As mentioned above it is more appropriate tocalculate the austenite content in textured specimens byaveraging the austenite contents obtained from all thepeaks ie lllallOm 200a200m and 220L2llmpeaks The volume percentage of aus~enite presented inthis work was calculated USIng the IntenSIty averagIngtechnique

EFFECT OF DEFORMATION ONREAUSTENITISATIONThe amount of austenite formed following aging dependsnot only on the temperature but also on the type and degreeof deformation The amounts of austenite formed at varioustemperatures for different degrees of deformatio i~partedby flow forming and cold rolling are presented In FIg 4 Itis evident that for aging temperatures up to 680degC thereverted austenite content for a particular aging temperaturegenerally increases with degree of deformation In contrast

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100 Ali et al Austenite reversion in cold formed maraging steel

5 Specimen aged at 620degC for 1 h showing growth ofaustenite along martensite lath boundaries (TEM)

6 Specimen aged at 680degC for 1 h showingrecrystallisation of martensite in present maragingsteel (TEM)

Table 3 Chemical composition of austenite formed inspecimen transformed at 650degC for 1 h wt-

at aging temperatures above 680degC the cold worked speci-mens show a lower volume percentage of reverted austenitein comparison with the annealed specimens

Similar results were obtained in specimens that weresubjected to cold rolling before austenitisation In thesespecimens 50-70 more reverted austenite was notedin comparison with the annealed material for agingtemperatures up to 680degC as shown in Fig 4b

The details regarding the mechanism through which thereversion of austenite occurs have been the subject of manyinvestigations1261415 It is fairly well established that inthe initial stages austenite usually forms as long thinplatelets on the martensite lath boundaries Increasing thearea of these boundaries through flow forming or rollingprobably increases the amount of austenite that formsfollowing aging The excessive defect density incorporatedduring cold forming aids by providing a much finerdistribution of precipitates that form and subsequentlydissolve to give nickel rich regions along the lathboundaries and within the laths The microstructural detailsof austenite reversion in 18Ni 350 maraging steel havebeen investigated and will be presented elsewhere16 Onlythe relevant information is given in the present paper Atransmission electron micrograph (TEM) obtained from aspecimen aged at 620degC for 1 h is shown in Fig 5 Thespecimen was subjected to cold rolling (50 reduction)before aging The austenite phase can be seen mostly alongthe lath boundaries This austenite was analysed using theEDX facility and the composition determined by averaging10 readings is given in Table 3

It is evident that substantial partitioning of alloyingelements must occur before the austenite phase becomesstable at room temperature The cold working by virtueof the excess defect density introduced initiates theprecipitation reaction at lower temperatures and thereaction proceeds at a much more rapid rate comparedwith that of the annealed specimens On subsequent agingthe finer distribution of precipitates results in relativelyrapid dissolution and a higher volume fraction of austeniteis obtained

The relatively rapid redissolution of austenite at highertemperatures can be explained using the same reasoning

Si

0middot08

Mo

5middot0

Ni

28middot0

Co

8middot0

Ti

0middot8

Fe

Bal

The refined microstructure and higher defect densitydecrease the recrystallisation temperature and rapid dissolu-tion occurs Figure 6 is a TEM from a specimen subjectedto aging for 1 h at 680degC Recrystallisation has taken placeresulting in redissolution of nickel and thereby renderingthe martensite phase stable at room temperature

Conclusions

Austenite reversion in deformed 18wt-Ni 350 grademaraging steel was investigated In textured specimensaustenite peaks were affected by the deformation processesand the reverted austenite content is more accuratelyquantified by averaging all the peaks The deformation ofmartensite also influences the volume fractions of revertedaustenite The increase in austenite content depends stronglyupon the amount and type of deformation

Acknowledgements

The authors are indebted to Mr T N Siddiqui andMr M Irfan for their assistance in conducting X-raydiffraction studies and Mr M Khalid and Mr T Mehmoodfor assistance with metallography and photography

References

1 S FLOREEN and R F DECKER in Source book on maragingsteels (ed R F Decker) 20-32 1979 Metals Park OR ASM

2 M SCHMIDT and K ROHRBACH in Metals handbook Vol 4219-228 1991 Materials Park OR ASM

3 R F DECKER J T EASH and A J GOLDMAN Trans ASM 19625558-76

4 K DETERT Trans ASM 1966 59 262-2765 M AHMED M FAROOQ F H HASHMI S W HUSSAIN and

A Q KHAN in Proc Conf Maraging steels recent develop-ments and applications (ed R K Wilson) 269-282 1988Warrendale PA TMS-AIME

6 D T PETERS in Source book on maraging steels (edR F Decker) 304-316 1979 Metals Park OR ASM

7 R A COVERT and E P SADOWSKI in Proc 22nd Annual NACEConfMiami Beach FL April 1966 National Association ofCorrosion Engineers

8 R L CAIRNS Trans ASM 1969 62 244-256

Materials Science and Technology February 1994 Vol 10

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9 B L AVERBACH and M COHEN Trans AIME 194817640110 B D CULLITY in Elements of X-ray diffraction 2 edn 411

1978 Reading MA Addison-Wesley11 B D CULLITY in Elements of X-ray diffraction 2 edn 523

1978 Reading MA Addison-Wesley12 B D CULLITY in Elements of X-ray diffraction 2 edn 136

1978 Reading MA Addison-Wesley13 F HABIBY T N SIDDIQUI H HUSSAIN M A KHAN A ul HAQ

and A Q KHAN Mater Sci Eng 1992 A159 261-265

Ali et al Austenite reversion in cold formed maraging steel 101

14 v K VASUDEVAN V K KIM and c M WAYMAN Metall Trans1990 21A 2655-2668

15 D T PETERS and c R CUPP in Source book on maragingsteels (ed R F Decker) 317-325 1979 Metals ParkOR ASM

16 M AHMED unpublished work Dr A Q Khan ResearchLaboratories Rawalpindi Pakistan 1993

Phase Diagrams and MicrostructureA Computer-Aided Learning GuideJohn Pilling

Known as PHAUST this computer software package is a teaching tool which illustrates thedynamics of microstructural evolution during the solidification of metals and its relationship with theappropriate phase diagrams The accompanying user manual acts as a study guide whichillustrates howto solve problems using PHAUST as well as describing the underlying metho~ologiesemployed by PHAUST to solve microstructural - phase diagram related problems

PHAUST operates through a graphical user interface allowing users to select for study only thoseareas which are of interest or appropriate difficulty rather than wade through all the examples as intraditional programmed learning Users can select a phase diagram from the database thataccompanies the programme or create their own using simple point and click drawing Users thengenerate the starting point for the problem effectively allowing an infinite number of problems andwith on-line help an infinite number of worked examples

Contents Hardware Requirements

This package runs on IBM compatible PCsrUnning MS-DOS with a minimum of 640KbRAM It requires a mouse and EGA graphics

Operation Creating Your Own Diagrams An Introduction to Binary Phase Diagrams Equilibrium Solidification Scheil Equation Suggested Further Reading andBibliography

A database of binary phase diagrams for AI- CU- Ni-base alloys Au Pb Sn Sb alloys and someceramic and geological systems and a microstructural database including common precipitatesmorphologies faceting and non-faceting eutectics is also included with the software

Order Code PD524 Disk 1 x 3511 Manual 100pp spiral bound ISBN 0901716 11 1pound9600 (incl VAT) US$19200Extra copies of the manual are available pound1500 US$3000

Orders with remittance to The Institute of Materials Sales amp Marketing Dept 1 Carlton HouseTerrace London SW1Y 50B Tel (071) 976 1338 Fax (071) 839 2078Orders originating in Canada and the United States should be sent direct to Ashgate PublishingCo Old Post Road Brookfield VT 05036 USA Tel (802) 276 3162 Fax (802)276 3837Carriage UK customers please add pound250 per order (incl VAT) overseas customers addUS$600

Materials Science and Technology February 1994 Vol 10

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Ali et al Austenite reversion in cold formed maraging steel 99

60FF77 200m200a

50 + FF87 200m200a

CR50 200m200a

40 30

Line of unit slope---- +20

+ +10(a)

O

60 x

FF40 ZII mZZOa

50 + FF57 ZllmZZOa FF77 Zllm2Z0a

0 +40 0 FF87 211m220a

tUX0 CR50 211m220a

CI t~ 30

~ 20

10 +---Line of unit slope (b)

00 10 20 30 40 50 60110m111a

3 Comparison of austenite volume fractions measuredusing a 110m111a and 200m200a andb110m111a and 211m220a peaks

50

40

~ 30Q)~cQ)~tn 20lt

10

070

60

50 Jr

~ lt7

(1) 40~c(1) 30-U)lt 20

10

(a)

- FF40

+ FF67

FF77

o FF87

--- Annealed

(b)

Annealed

- CR50-J CR85 ~

peak intensities of different peaks Such an effect isdemonstrable for cold formed maraging steel

Figure 1 shows the X-ray spectra obtained from annealedflow formed (FF) and cold rolled (CR) specimens Therelative peak intensities from an annealed specimen corre-spond to values that are expected for a hom~ge~eous ~~dequiaxed specimen of maraging steel The relatIve IntensItIesstart to change when reduction ratios above 50 areemployed for flow formed material This effect becomesmuch more pronounced after 75 reduction The llOmand 2llm peaks are most severely affected A similartendency was observed in specimens subjected to cldrolling Specimens cold rolled beyond 25 reductIonstarted to show this effect At 50 reduction the spectrumintensities appeared similar to those for the flow formedmaterial after 75 reduction Detailed texture analysis wasnot carried out in this investigation However the changein relative peak intensities is undoubtedly due to textureincorporated during flow forming and rolling10

The texture incorporated during cold working influencesthe austenite peaks obtained following aging Figure 2shows spectra obtained from annealed flow formed andcold worked specimens after subsequent aging at 680degC ~or1 h In the annealed specimen the expected llla austenItepeak is pronounced In deformed specimens however ~hellla austenite peak is obviously affected by deformatIontexture At reduction ratios above 25 200a and 220a austenite peaks appear and the lll L peak intensitydecreases It is also obvious from the spectra of flow formedspecimens that the relati~e inten~ities of allstenite ~eaksincreased with deformatIon ratIo sIgnIfYIng a hIgherpercentage of reverted austenite In cold rolled specimessimilar texture effects were observed the 220a austenItepeak being most prominent

In calculating the volume fractIon of austenIte textureeffects can be overcome by averaging the austenite contentscalculated from all the austenite peaks Measuring all thelines and averaging in the prescribed manner will yieldvalid data In the literature10 this method has been termedthe intensity averaging technique The basic concept in

o600 620 640 660 680 700 720 740

Temperature (0 C)4 Effect of reaustenitisation temperature on volume

fraction of austenite in a flow formed and b coldrolled specimens

the intensity averaging technique is simple if certain linesfrom the austenite phase are abnormally weak because oftexture the other austenite lines will be abnormallystrong (Fig 2)

If the intensity averaging of all the peaks is not carriedout considerable errors may result as is demonstratedbelow The volume fraction of austenite measured usingtwo possible selections of peaks is plotted in Fig 3 InFig3a austenite content is calculated from l1lalIOmand compared with 200a200m whereas in Fig 3baustenite content is measured by comparing lllallOmwith 220a2llm peaks Figure 3 shows variable corre-lation and a large scatter in the austenite content Aselected combination of peaks should not be used incalculating the volume fraction of austenite in texturedspecimens As mentioned above it is more appropriate tocalculate the austenite content in textured specimens byaveraging the austenite contents obtained from all thepeaks ie lllallOm 200a200m and 220L2llmpeaks The volume percentage of aus~enite presented inthis work was calculated USIng the IntenSIty averagIngtechnique

EFFECT OF DEFORMATION ONREAUSTENITISATIONThe amount of austenite formed following aging dependsnot only on the temperature but also on the type and degreeof deformation The amounts of austenite formed at varioustemperatures for different degrees of deformatio i~partedby flow forming and cold rolling are presented In FIg 4 Itis evident that for aging temperatures up to 680degC thereverted austenite content for a particular aging temperaturegenerally increases with degree of deformation In contrast

Materials Science and Technology February 1994 Vol 10

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100 Ali et al Austenite reversion in cold formed maraging steel

5 Specimen aged at 620degC for 1 h showing growth ofaustenite along martensite lath boundaries (TEM)

6 Specimen aged at 680degC for 1 h showingrecrystallisation of martensite in present maragingsteel (TEM)

Table 3 Chemical composition of austenite formed inspecimen transformed at 650degC for 1 h wt-

at aging temperatures above 680degC the cold worked speci-mens show a lower volume percentage of reverted austenitein comparison with the annealed specimens

Similar results were obtained in specimens that weresubjected to cold rolling before austenitisation In thesespecimens 50-70 more reverted austenite was notedin comparison with the annealed material for agingtemperatures up to 680degC as shown in Fig 4b

The details regarding the mechanism through which thereversion of austenite occurs have been the subject of manyinvestigations1261415 It is fairly well established that inthe initial stages austenite usually forms as long thinplatelets on the martensite lath boundaries Increasing thearea of these boundaries through flow forming or rollingprobably increases the amount of austenite that formsfollowing aging The excessive defect density incorporatedduring cold forming aids by providing a much finerdistribution of precipitates that form and subsequentlydissolve to give nickel rich regions along the lathboundaries and within the laths The microstructural detailsof austenite reversion in 18Ni 350 maraging steel havebeen investigated and will be presented elsewhere16 Onlythe relevant information is given in the present paper Atransmission electron micrograph (TEM) obtained from aspecimen aged at 620degC for 1 h is shown in Fig 5 Thespecimen was subjected to cold rolling (50 reduction)before aging The austenite phase can be seen mostly alongthe lath boundaries This austenite was analysed using theEDX facility and the composition determined by averaging10 readings is given in Table 3

It is evident that substantial partitioning of alloyingelements must occur before the austenite phase becomesstable at room temperature The cold working by virtueof the excess defect density introduced initiates theprecipitation reaction at lower temperatures and thereaction proceeds at a much more rapid rate comparedwith that of the annealed specimens On subsequent agingthe finer distribution of precipitates results in relativelyrapid dissolution and a higher volume fraction of austeniteis obtained

The relatively rapid redissolution of austenite at highertemperatures can be explained using the same reasoning

Si

0middot08

Mo

5middot0

Ni

28middot0

Co

8middot0

Ti

0middot8

Fe

Bal

The refined microstructure and higher defect densitydecrease the recrystallisation temperature and rapid dissolu-tion occurs Figure 6 is a TEM from a specimen subjectedto aging for 1 h at 680degC Recrystallisation has taken placeresulting in redissolution of nickel and thereby renderingthe martensite phase stable at room temperature

Conclusions

Austenite reversion in deformed 18wt-Ni 350 grademaraging steel was investigated In textured specimensaustenite peaks were affected by the deformation processesand the reverted austenite content is more accuratelyquantified by averaging all the peaks The deformation ofmartensite also influences the volume fractions of revertedaustenite The increase in austenite content depends stronglyupon the amount and type of deformation

Acknowledgements

The authors are indebted to Mr T N Siddiqui andMr M Irfan for their assistance in conducting X-raydiffraction studies and Mr M Khalid and Mr T Mehmoodfor assistance with metallography and photography

References

1 S FLOREEN and R F DECKER in Source book on maragingsteels (ed R F Decker) 20-32 1979 Metals Park OR ASM

2 M SCHMIDT and K ROHRBACH in Metals handbook Vol 4219-228 1991 Materials Park OR ASM

3 R F DECKER J T EASH and A J GOLDMAN Trans ASM 19625558-76

4 K DETERT Trans ASM 1966 59 262-2765 M AHMED M FAROOQ F H HASHMI S W HUSSAIN and

A Q KHAN in Proc Conf Maraging steels recent develop-ments and applications (ed R K Wilson) 269-282 1988Warrendale PA TMS-AIME

6 D T PETERS in Source book on maraging steels (edR F Decker) 304-316 1979 Metals Park OR ASM

7 R A COVERT and E P SADOWSKI in Proc 22nd Annual NACEConfMiami Beach FL April 1966 National Association ofCorrosion Engineers

8 R L CAIRNS Trans ASM 1969 62 244-256

Materials Science and Technology February 1994 Vol 10

Pub

lishe

d by

Man

ey P

ublis

hing

(c)

IOM

Com

mun

icat

ions

Ltd

9 B L AVERBACH and M COHEN Trans AIME 194817640110 B D CULLITY in Elements of X-ray diffraction 2 edn 411

1978 Reading MA Addison-Wesley11 B D CULLITY in Elements of X-ray diffraction 2 edn 523

1978 Reading MA Addison-Wesley12 B D CULLITY in Elements of X-ray diffraction 2 edn 136

1978 Reading MA Addison-Wesley13 F HABIBY T N SIDDIQUI H HUSSAIN M A KHAN A ul HAQ

and A Q KHAN Mater Sci Eng 1992 A159 261-265

Ali et al Austenite reversion in cold formed maraging steel 101

14 v K VASUDEVAN V K KIM and c M WAYMAN Metall Trans1990 21A 2655-2668

15 D T PETERS and c R CUPP in Source book on maragingsteels (ed R F Decker) 317-325 1979 Metals ParkOR ASM

16 M AHMED unpublished work Dr A Q Khan ResearchLaboratories Rawalpindi Pakistan 1993

Phase Diagrams and MicrostructureA Computer-Aided Learning GuideJohn Pilling

Known as PHAUST this computer software package is a teaching tool which illustrates thedynamics of microstructural evolution during the solidification of metals and its relationship with theappropriate phase diagrams The accompanying user manual acts as a study guide whichillustrates howto solve problems using PHAUST as well as describing the underlying metho~ologiesemployed by PHAUST to solve microstructural - phase diagram related problems

PHAUST operates through a graphical user interface allowing users to select for study only thoseareas which are of interest or appropriate difficulty rather than wade through all the examples as intraditional programmed learning Users can select a phase diagram from the database thataccompanies the programme or create their own using simple point and click drawing Users thengenerate the starting point for the problem effectively allowing an infinite number of problems andwith on-line help an infinite number of worked examples

Contents Hardware Requirements

This package runs on IBM compatible PCsrUnning MS-DOS with a minimum of 640KbRAM It requires a mouse and EGA graphics

Operation Creating Your Own Diagrams An Introduction to Binary Phase Diagrams Equilibrium Solidification Scheil Equation Suggested Further Reading andBibliography

A database of binary phase diagrams for AI- CU- Ni-base alloys Au Pb Sn Sb alloys and someceramic and geological systems and a microstructural database including common precipitatesmorphologies faceting and non-faceting eutectics is also included with the software

Order Code PD524 Disk 1 x 3511 Manual 100pp spiral bound ISBN 0901716 11 1pound9600 (incl VAT) US$19200Extra copies of the manual are available pound1500 US$3000

Orders with remittance to The Institute of Materials Sales amp Marketing Dept 1 Carlton HouseTerrace London SW1Y 50B Tel (071) 976 1338 Fax (071) 839 2078Orders originating in Canada and the United States should be sent direct to Ashgate PublishingCo Old Post Road Brookfield VT 05036 USA Tel (802) 276 3162 Fax (802)276 3837Carriage UK customers please add pound250 per order (incl VAT) overseas customers addUS$600

Materials Science and Technology February 1994 Vol 10

Pub

lishe

d by

Man

ey P

ublis

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(c)

IOM

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ions

Ltd

100 Ali et al Austenite reversion in cold formed maraging steel

5 Specimen aged at 620degC for 1 h showing growth ofaustenite along martensite lath boundaries (TEM)

6 Specimen aged at 680degC for 1 h showingrecrystallisation of martensite in present maragingsteel (TEM)

Table 3 Chemical composition of austenite formed inspecimen transformed at 650degC for 1 h wt-

at aging temperatures above 680degC the cold worked speci-mens show a lower volume percentage of reverted austenitein comparison with the annealed specimens

Similar results were obtained in specimens that weresubjected to cold rolling before austenitisation In thesespecimens 50-70 more reverted austenite was notedin comparison with the annealed material for agingtemperatures up to 680degC as shown in Fig 4b

The details regarding the mechanism through which thereversion of austenite occurs have been the subject of manyinvestigations1261415 It is fairly well established that inthe initial stages austenite usually forms as long thinplatelets on the martensite lath boundaries Increasing thearea of these boundaries through flow forming or rollingprobably increases the amount of austenite that formsfollowing aging The excessive defect density incorporatedduring cold forming aids by providing a much finerdistribution of precipitates that form and subsequentlydissolve to give nickel rich regions along the lathboundaries and within the laths The microstructural detailsof austenite reversion in 18Ni 350 maraging steel havebeen investigated and will be presented elsewhere16 Onlythe relevant information is given in the present paper Atransmission electron micrograph (TEM) obtained from aspecimen aged at 620degC for 1 h is shown in Fig 5 Thespecimen was subjected to cold rolling (50 reduction)before aging The austenite phase can be seen mostly alongthe lath boundaries This austenite was analysed using theEDX facility and the composition determined by averaging10 readings is given in Table 3

It is evident that substantial partitioning of alloyingelements must occur before the austenite phase becomesstable at room temperature The cold working by virtueof the excess defect density introduced initiates theprecipitation reaction at lower temperatures and thereaction proceeds at a much more rapid rate comparedwith that of the annealed specimens On subsequent agingthe finer distribution of precipitates results in relativelyrapid dissolution and a higher volume fraction of austeniteis obtained

The relatively rapid redissolution of austenite at highertemperatures can be explained using the same reasoning

Si

0middot08

Mo

5middot0

Ni

28middot0

Co

8middot0

Ti

0middot8

Fe

Bal

The refined microstructure and higher defect densitydecrease the recrystallisation temperature and rapid dissolu-tion occurs Figure 6 is a TEM from a specimen subjectedto aging for 1 h at 680degC Recrystallisation has taken placeresulting in redissolution of nickel and thereby renderingthe martensite phase stable at room temperature

Conclusions

Austenite reversion in deformed 18wt-Ni 350 grademaraging steel was investigated In textured specimensaustenite peaks were affected by the deformation processesand the reverted austenite content is more accuratelyquantified by averaging all the peaks The deformation ofmartensite also influences the volume fractions of revertedaustenite The increase in austenite content depends stronglyupon the amount and type of deformation

Acknowledgements

The authors are indebted to Mr T N Siddiqui andMr M Irfan for their assistance in conducting X-raydiffraction studies and Mr M Khalid and Mr T Mehmoodfor assistance with metallography and photography

References

1 S FLOREEN and R F DECKER in Source book on maragingsteels (ed R F Decker) 20-32 1979 Metals Park OR ASM

2 M SCHMIDT and K ROHRBACH in Metals handbook Vol 4219-228 1991 Materials Park OR ASM

3 R F DECKER J T EASH and A J GOLDMAN Trans ASM 19625558-76

4 K DETERT Trans ASM 1966 59 262-2765 M AHMED M FAROOQ F H HASHMI S W HUSSAIN and

A Q KHAN in Proc Conf Maraging steels recent develop-ments and applications (ed R K Wilson) 269-282 1988Warrendale PA TMS-AIME

6 D T PETERS in Source book on maraging steels (edR F Decker) 304-316 1979 Metals Park OR ASM

7 R A COVERT and E P SADOWSKI in Proc 22nd Annual NACEConfMiami Beach FL April 1966 National Association ofCorrosion Engineers

8 R L CAIRNS Trans ASM 1969 62 244-256

Materials Science and Technology February 1994 Vol 10

Pub

lishe

d by

Man

ey P

ublis

hing

(c)

IOM

Com

mun

icat

ions

Ltd

9 B L AVERBACH and M COHEN Trans AIME 194817640110 B D CULLITY in Elements of X-ray diffraction 2 edn 411

1978 Reading MA Addison-Wesley11 B D CULLITY in Elements of X-ray diffraction 2 edn 523

1978 Reading MA Addison-Wesley12 B D CULLITY in Elements of X-ray diffraction 2 edn 136

1978 Reading MA Addison-Wesley13 F HABIBY T N SIDDIQUI H HUSSAIN M A KHAN A ul HAQ

and A Q KHAN Mater Sci Eng 1992 A159 261-265

Ali et al Austenite reversion in cold formed maraging steel 101

14 v K VASUDEVAN V K KIM and c M WAYMAN Metall Trans1990 21A 2655-2668

15 D T PETERS and c R CUPP in Source book on maragingsteels (ed R F Decker) 317-325 1979 Metals ParkOR ASM

16 M AHMED unpublished work Dr A Q Khan ResearchLaboratories Rawalpindi Pakistan 1993

Phase Diagrams and MicrostructureA Computer-Aided Learning GuideJohn Pilling

Known as PHAUST this computer software package is a teaching tool which illustrates thedynamics of microstructural evolution during the solidification of metals and its relationship with theappropriate phase diagrams The accompanying user manual acts as a study guide whichillustrates howto solve problems using PHAUST as well as describing the underlying metho~ologiesemployed by PHAUST to solve microstructural - phase diagram related problems

PHAUST operates through a graphical user interface allowing users to select for study only thoseareas which are of interest or appropriate difficulty rather than wade through all the examples as intraditional programmed learning Users can select a phase diagram from the database thataccompanies the programme or create their own using simple point and click drawing Users thengenerate the starting point for the problem effectively allowing an infinite number of problems andwith on-line help an infinite number of worked examples

Contents Hardware Requirements

This package runs on IBM compatible PCsrUnning MS-DOS with a minimum of 640KbRAM It requires a mouse and EGA graphics

Operation Creating Your Own Diagrams An Introduction to Binary Phase Diagrams Equilibrium Solidification Scheil Equation Suggested Further Reading andBibliography

A database of binary phase diagrams for AI- CU- Ni-base alloys Au Pb Sn Sb alloys and someceramic and geological systems and a microstructural database including common precipitatesmorphologies faceting and non-faceting eutectics is also included with the software

Order Code PD524 Disk 1 x 3511 Manual 100pp spiral bound ISBN 0901716 11 1pound9600 (incl VAT) US$19200Extra copies of the manual are available pound1500 US$3000

Orders with remittance to The Institute of Materials Sales amp Marketing Dept 1 Carlton HouseTerrace London SW1Y 50B Tel (071) 976 1338 Fax (071) 839 2078Orders originating in Canada and the United States should be sent direct to Ashgate PublishingCo Old Post Road Brookfield VT 05036 USA Tel (802) 276 3162 Fax (802)276 3837Carriage UK customers please add pound250 per order (incl VAT) overseas customers addUS$600

Materials Science and Technology February 1994 Vol 10

Pub

lishe

d by

Man

ey P

ublis

hing

(c)

IOM

Com

mun

icat

ions

Ltd

9 B L AVERBACH and M COHEN Trans AIME 194817640110 B D CULLITY in Elements of X-ray diffraction 2 edn 411

1978 Reading MA Addison-Wesley11 B D CULLITY in Elements of X-ray diffraction 2 edn 523

1978 Reading MA Addison-Wesley12 B D CULLITY in Elements of X-ray diffraction 2 edn 136

1978 Reading MA Addison-Wesley13 F HABIBY T N SIDDIQUI H HUSSAIN M A KHAN A ul HAQ

and A Q KHAN Mater Sci Eng 1992 A159 261-265

Ali et al Austenite reversion in cold formed maraging steel 101

14 v K VASUDEVAN V K KIM and c M WAYMAN Metall Trans1990 21A 2655-2668

15 D T PETERS and c R CUPP in Source book on maragingsteels (ed R F Decker) 317-325 1979 Metals ParkOR ASM

16 M AHMED unpublished work Dr A Q Khan ResearchLaboratories Rawalpindi Pakistan 1993

Phase Diagrams and MicrostructureA Computer-Aided Learning GuideJohn Pilling

Known as PHAUST this computer software package is a teaching tool which illustrates thedynamics of microstructural evolution during the solidification of metals and its relationship with theappropriate phase diagrams The accompanying user manual acts as a study guide whichillustrates howto solve problems using PHAUST as well as describing the underlying metho~ologiesemployed by PHAUST to solve microstructural - phase diagram related problems

PHAUST operates through a graphical user interface allowing users to select for study only thoseareas which are of interest or appropriate difficulty rather than wade through all the examples as intraditional programmed learning Users can select a phase diagram from the database thataccompanies the programme or create their own using simple point and click drawing Users thengenerate the starting point for the problem effectively allowing an infinite number of problems andwith on-line help an infinite number of worked examples

Contents Hardware Requirements

This package runs on IBM compatible PCsrUnning MS-DOS with a minimum of 640KbRAM It requires a mouse and EGA graphics

Operation Creating Your Own Diagrams An Introduction to Binary Phase Diagrams Equilibrium Solidification Scheil Equation Suggested Further Reading andBibliography

A database of binary phase diagrams for AI- CU- Ni-base alloys Au Pb Sn Sb alloys and someceramic and geological systems and a microstructural database including common precipitatesmorphologies faceting and non-faceting eutectics is also included with the software

Order Code PD524 Disk 1 x 3511 Manual 100pp spiral bound ISBN 0901716 11 1pound9600 (incl VAT) US$19200Extra copies of the manual are available pound1500 US$3000

Orders with remittance to The Institute of Materials Sales amp Marketing Dept 1 Carlton HouseTerrace London SW1Y 50B Tel (071) 976 1338 Fax (071) 839 2078Orders originating in Canada and the United States should be sent direct to Ashgate PublishingCo Old Post Road Brookfield VT 05036 USA Tel (802) 276 3162 Fax (802)276 3837Carriage UK customers please add pound250 per order (incl VAT) overseas customers addUS$600

Materials Science and Technology February 1994 Vol 10