Effect of heating mode and electrochemical response … · Effect of heating mode and...

Effect of heating mode and electrochemicalresponse on austenitic and ferritic stainlesssteels

A. Raja Annamalai*1,3, A. Upadhyaya1 and D. K. Agrawal2

Powder metallurgical (P/M) processing has the main advantage of making near net shape

products. Nowadays, in automobile industries, stainless steels have become the most promising

material owing to their good corrosion resistance. In the current study, 316L and 434L stainless

steel powders were sintered using microwave and conventional methods through powder

metallurgy route. The effects of sintering modes on the microstructure, mechanical properties and

corrosion responses of 316L and 434L stainless steel composites are investigated in detail. The

results showed that the sample prepared through microwave sintering route exhibited

significantly superior densification, higher hardness and better corrosion resistance as compared

to the conventionally processed counterpart. On the whole, 316L composites showed better

corrosion resistance than 434L stainless steels.

Le traitement par metallurgie des poudres (P/M) a pour avantage principal de fabriquer des produits

a forme extremement precise. De nos jours dans l’industrie de l’automobile, les aciers inoxydables

sont maintenant le materiau le plus promettant grace a leur bonne resistance a la corrosion. Dans

l’etude courante, on a fritte des poudres d’acier inoxydable 316L et 434L en utilisant les micro-ondes

et des methodes conventionnelles par la route de la metallurgie des poudres. On examine en detail

les effets du mode de frittage sur la microstructure, les proprietes mecaniques et les reponses a la

corrosion des composites d’acier inoxydable 316L et 434L. Les resultats ont montre que l’echantillon

prepare par la route du frittage aux micro-ondes exhibait une densification significativement

superieure, une durete plus elevee et une meilleure resistance a la corrosion par rapport a sa

contrepartie traitee conventionnellement. Dans l’ensemble, les composites de 316L ont montre une

meilleure resistance a la corrosion que les aciers inoxydables 434L.

Keywords: Powder metallurgy, Microwave, Sintering, Stainless steel, Electrochemical

IntroductionStainless steel constitutes one of the important groups offerrous systems having higher alloying content. Theimportance of stainless steels is because of its superiorcorrosion resistance due to the formation of adherent

Cr2O3 on the surface. Despite the advances in theproduction of prealloyed stainless powders with tailoredcompositions,1 the application of powder metallurgical(P/M) stainless steels is still limited.2,3 This is due to thepresence of residual porosity during sintering that resultin inferior corrosion resistance in sintered stainless steelrelative to their wrought counter parts.4 Most stainlesssteel components are usually consolidated by solid statesintering at temperatures ranging from 1100 to 1250uC.Because of slower densification kinetics, the as-sinteredcompacts contain up to 15–20% porosity.4 It is wellknown that the presence of porosity in P/M stainlesssteel acts as pre-existing crevices, which degrade theoverall corrosion resistance.5,6 The prealloyed stainless

1Department of Materials Science and Engineering, Indian Institute ofTechnology Kanpur, Kanpur 208016, India2Materials Research Institute, The Pennsylvania State University,University Park, PA 16802, USA3Manufacturing Division, VIT University, Vellore, 632 014, Tamil Nadu,India

*Corresponding author, email [email protected]

142

� 2015 Canadian Institute of Mining, Metallurgy and PetroleumPublished by Maney on behalf of the InstituteReceived 6 March 2014; accepted 12 January 2015DOI 10.1179/1879139515Y.0000000001 Canadian Metallurgical Quarterly 2015 VOL 54 NO 2

steel powders can be consolidated only through super-solidus sintering,7 which in turn is difficult to control.However, to achieve optimal mechanical properties,some additives are used in very small proportions.Consequently, they do not result in significant densifica-tion enhancement8,9 and resulted in more inferiorcorrosion resistance.9–13 Garcıa et al.14 studied the sin-tering cooling rate on corrosion resistance on duplexstainless steels and they found that gas cooling waspreferred for austenitic stainless steel. Recently, Fredri-ksson et al.15 compared the austenitic 316L and duplex2205 P/M steels and they found that 316L steel is shownto have significantly higher pitting corrosion resistancethan conventional 316L steel in 0?5M HCl. Microwavesintering is an emerging sintering technique that employsa volumetric microwave heating and enables a fasterheating rate as compared to conventional radiativeheating and thus results in a very short sintering cycle,typically a few minutes for full densification especiallyin the case of conductive powders.16 However, till date,there is no investigation on microwave sintering of316L and 434L stainless steels. This study thereforeaims at investigating the effect of heating mode on thedensification response, hardness and electrochemicalbehaviour of austenitic and ferritic stainless steel.

Experimental procedureFor the present investigation, austenitic and ferriticgrades were selected. The stainless steel powders weresupplied by Ametek Specialty Metals Products (USA).The nominal compositions of the powders used in thepresent investigation are summarised in Table 1. Forboth grades, the powders were prepared by gasatomisation and were in prealloyed form. The char-acteristics of the as received powders are detailed inTable 2. The powders were uniaxially compacted at600 MPa to cylindrical pellets (16 mm diameter and6 mm height) using a hydraulic press (model: CTM-100;Blue Star, India) using zinc stearate as a die walllubricant. The green densities of the compacts werefound to be around 80% of theoretical density. Sinteringwas carried out in hydrogen atmosphere (dew point:235uC) in a MoSi2 heated horizontal tubular sinteringfurnace (model: OKAY 70T-7; Bysakh, Kolkata, India)at a constant heating rate of 5uC min21. The compactswere consolidated isothermally at 1350uC for 1 h. Twointermediate isothermal holds at 600 and 900uC wereprovided for delubrication/debinding and reduction ofoxides respectively. The microwave sintering experi-ments were carried out using a 6 kW, 2?45 GHz,multimode microwave furnace. Temperature measure-ment was made with an optical pyrometer (Raytek,Marathon Series), through a small quartz window at the

top of the furnace. After sintering, the microwave powerwas switched off and samples were allowed to furnacecool.

The sintered density was determined using Archi-medes method. For microstructural and electrochemicalanalyses, the samples were polished to mirror finish andultrasonically cleaned in acetone. The micro structuralanalyses of the samples were carried out through opticalmicroscope (model: DM2500; Leica Imaging SystemLtd, Cambridge, UK). The sintered compacts wereetched using Marble’s reagent. Bulk hardness of thesamples was measured using Vickers hardness tester(Leco V-100-C1 Hardness Tester) at 5 kg load. Toensure reproducibility, five samples were tested. Thescanning electron microstructure of the samples wereobtained using backscattered electron imaging mode(Zeiss Evo 50; Carl Zeiss SMT Ltd, UK). The elec-trochemical behaviour of the samples was studied infreely aerated 0?1 N H2SO4 solution (pH 1?31¡0?4)using Electrochemical System (model: Versa STAT 3;Princeton Applied Research). Before polarisation, thepolished samples were allowed to stabilise for 3600 sfor obtaining stable open circuit potential (OCP). Elec-trochemical tests were carried out in a flat corrosion cell(Accutrol Inc., USA) using a standard three-electrodeconfiguration with the sample as the working electrode,platinum mesh as the counter electrode and Ag/AgCl(saturated with KCl) as reference electrode (197 mV).The polarisation tests were carried out from 2250 to250 mV(OCP) in the case of Tafel and 2250 mV(OCP)to z1600 mV versus reference electrode in case ofpotentiodynamic at a scan rate of 0?5 mV s21. The Tafelslopes were established from the corresponding anodicand cathodic curves. The corrosion potential (Ecorr) andcorrosion current (Icorr) and corrosion rate weredetermined from the polarisation curves. The corrosionrate (mm/year) can be determined using first Sternmethod17 and is expressed as follows

Table 1 Composition of austenitic and ferritic grade stainless steels used in present study

Grade* Composition/wt-%

316L Fe–16.5Cr–12.97Ni–2.48Mo–0.93Si–0.21Mn–0.025C–0.008S–0.01P–0O2

434L Fe–17Cr–1Mo–0.71Si–0.2Mn–0.02C–0.02S–0.02P–0O2

*Supplier: Ametek Specialty Metals Products, USA.

Table 2 Characteristics of powders in as receivedconditions used in present study

PropertyPowder

316L 434L

Processing technique Gas atomisation Gas atomisationPowder shape Rounded SphericalCumulative powder size/mD10 10.3 8.35D50 45.9 35.3D90 85.1 75.1Apparent density, g/cm3 2.7 2.6Flowrate/s/50 g 28 28Theoretical density/g cm23 8.06 7.86

Raja Annamalai et al. Electrochemical response on 316L and 434L stainless steels

Canadian Metallurgical Quarterly 2015 VOL 54 NO 2 143

Corrosion rate~0:0033e

rIcorr

where e is the equivalent weight (g), r is the density ofthe material (mg m23) and Icorr is the corrosion current(mA m22).

Results and discussionFigure 1 compares the thermal profiles of the stainlesssteel compacts consolidated using a resistance heatingfurnace and a 2?45 GHz multimode microwave furnace.It is interesting to note that both 316L as well as 434Lcompacts exhibit strong coupling with microwaves andundergo rapid heating. Owing to the limitations ofoptical and infrared pyrometers, the temperature couldonly be measured from 200uC onwards. However, ittook about 4 min for the samples to get heated up tothat temperature in the microwave furnace. The overall(averaged) heating rates achieved in the microwavefurnace were found to be around 45uC min21. It isevident that as compared to conventional furnaceheating, microwave heating results in about 85%reduction in sintering time. Elsewhere, Panda et al.4

reported up to 90% reduction in sintering time inthe case of microwave processed stainless steels. Oneinteresting observation in Fig. 1 is the differentialcoupling of microwaves with austenitic and ferriticgrade stainless steels. This results in a slight differencein the heating rate of the compacts. The 434L grade

stainless steels seem to heat at a relatively faster ratethan the 316L grade. They can be correlated to the factthat besides the electric field (E), the magnetic compo-nent (H) present in the ferritic stainless steel interactswith the microwaves. The contributions of the individualfields on the heating behaviour of ferrous powders wereevaluated in single mode microwave furnace by Chenget al.18,19 Both have shown that under the H fieldmagnetic ferrous powders undergo more rapid heating.

Table 3 compares the densification response of 316Land 434L grade stainless steels sintered in conventionalas well as microwave furnace. The trend in densificationreveals that for both 316L and 434L powder compacts,microwave sintering results in higher density levels thanthose achieved through conventional sintering (Table 3).For both the grades, microwave sintering has resultedin higher densification as compared to conventionalfurnace sintering. The increase in the densification ismuch more prominent for ferritic (434L) stainless steels.This is further validated by comparing the densificationparameters which follows a similar trend as the sintereddensity (Table 3). Elsewhere, Saitou20 and Panda et al.4

have shown the improved densification in compactsconsolidated through microwave sintering. It is interest-ing to note that irrespective of the heating mode, theferritic stainless compacts undergo a higher densificationas compared to their austenitic counterparts. This can beattributed to relatively higher diffusivity in the moreopen body centred cubic structure of the 434L compacts.This can be attributed to lower microstructural coarsen-ing in the rapidly heated compacts. Consequently, at theparts heated to the sintering temperature in microwavefurnace have larger surface area available. This pro-motes greater contribution of grain boundary diffusionto the densification. For 316L compacts, the densityachieved through conventional sintering at 1350uC(6?6 g cm23) is similar to that reported by others1,21

and is equivalent to grade SS-316L-15 as per MPIFStandard 35.22 For the sintering temperature employed,the density achieved in 434L compacts through micro-wave sintering (7 g cm23) is higher than those reportedin literature1,23 and is equivalent to that specified byMPIF Standard 35.22

The effect of heating mode on the bulk hardness of thesintered stainless steel is summarised in Table 3. Notethat microwave sintering results in marginally higherhardness in 316L stainless steel. The effect of heatingmode on the hardness is more pronounced for 434Lstainless steels. As compared to conventional sintering,microwave sintered 434L compacts have about 15%higher hardness. The higher hardness in microwave

1 Effect of heating mode on thermal profiles of particu-

late compacts prepared using austenitic (316L) and fer-

ritic (434L) grade stainless steels: compacts were

pressed at 600 MPa and heated up to 1350uC in redu-

cing atmosphere

Table 3 Effect of heating mode on sintered density, densification parameter and bulk hardness of 316L and 434Lstainless steel compacts sintered at 1350uC

316L 434L

Conventional Microwave Conventional Microwave

Sintered density/g cm23 (% theoretical) 6.58 (81.6) 6.69 (83.0) 6.07 (77.2) 6.96 (88.5)Densification parameter 0.04 0.15 0.10 0.48Bulk hardness/HV5 82 85 100 115


144 Canadian Metallurgical Quarterly 2015 VOL 54 NO 2

sintered compacts can be attributed to the relativelylower levels of porosity in the compacts. Panda et al.4

have already correlated the relatively inferior tensileproperties in the microwave sintered 316L and 434Lgrade stainless steels (as compared to conventionallysintered compacts) with the preponderance of relativelyirregular pores. Hence, the scope of this study was limitedto hardness measurements only, and instead, the corro-sion response was dealt with. The trend in hardness ofsintered stainless steel as a function of the heating mode issimilar to that observed for sintered density. The hardnessof sintered 434L and 316L pellets are similar to thosereported by Upadhyaya and Mukherjee23 and Uzunsoy,24

respectively.

Figure 2 shows the microstructures of 316L and 434Lstainless steel consolidated conventionally as well asthrough microwave sintering. On comparing, it is quiteevident that for both stainless steel grades, microwavesintering restricts microstructural coarsening. The mi-crowave sintering does not lead to an appreciablechange in the shape of pores. Elsewhere, Fig. 3 showsthe effect of sintering mode on the OCP variation withtime in 0?1 N sulphuric acid for 316L and 434L stainlesssteel respectively. Note that for both the grades,irrespective of the heating mode, the OCP moderatelyincreases with time and attains a less negative value.This implies that the compact surface on prolongedexposure to 0?1 N H2SO4 attains a nobler characteristic.

2 SEM images showing microstructures of a 316L and b 434L compacts sintered at 1350uC for 60 min in conventional

(left) and microwave (right) furnace

3 OCP values of a austenitic 316L and b ferritic 434L stainless steels



This could be because of the formation of a protectivelayer (Cr2O3) on the surface. On prolonged immersion,the gradual increase in the potential can be attributed tothe reformation of the passive film. The variation in theOCP with times gives a qualitative indicator of thecorrosion response. The sintered compacts having lowerporosity always stabilise with more positive OCPs ascompared to those that sintered poorly.6 Elsewhere,Jones25 has shown that the pores acts as pre-existingcrevices on the sintered surfaces and can influence theOCP of the system. The trend in the OCP (Fig. 3) andEcorr (Table 4) validate this. For both 316L and 434Lcompacts, microwave sintering resulted in higher densi-fication. Consequently, the Ecorr values were less nega-tive. The OCP stabilisation curves (Fig. 3) indicate thatboth the stainless steel grades, irrespective of sinteringmodes, show a progressive variation towards a lessnegative potential. As compared to conventional sinter-ing, the microwave sintered compacts show stabilisationat relatively less active potential (Fig. 3). The effect ofsintered density on the improvement in the corrosionresistance in stainless steel is well documented.6,11,12 Thepores have twofold effect. They increase the overallsurface exposed to the electrolyte and thereby, increasecorrosion rate. Furthermore, the pores act as crevicesand lead to the formation of local concentrationcells.10–12 Pores and grain boundaries are potential sitesfor the initiation of corrosion. In the pores, a point isreached where the oxygen is used up, while the surfacehas immediate access to oxygen.26 Under these condi-tions, active condition within the pores is found and

active passive cells are set up. The main bulk surface istherefore assumed to act as cathode with respect to thepores. These active regions are preferred sites for co-rrosion attack. Itzhak and co-workers27–30 have attrib-uted the poor corrosion behaviour (in acidic medium)of sintered stainless steel to the stagnation of electro-lyte in the interconnected porosity, which caused for-mation of hydrogen concentration cell. The kinetics ofreaction is described by the corrosion current and whenrelated to the potential by means of polarisationdata, may give a fairly quantitative description of thecorrosion process.9

Figure 4 compares the corresponding potentiody-namic polarisation curves for both the stainless steelgrades (316L and 434L) sintered through conventionaland microwave sintering. Unlike sintered 316L alloys,the polarisation in anodic region exhibits an active–passive transition for 434L stainless steels (Fig. 4b). Thesintered austenitic steel exhibit a stable passive beha-viour; the ferritic stainless steels show an abrupt activepassive transition. Overall, the polarisation curves formicrowave sintered compacts are skewed towards lowercurrent density. This indicates propensity for microwavesintered compacts to form a more stable surface oxidelayer. In fact, both the Icorr and the corrosion rateobtained in microwave sintered 316L are comparable tothose reported for wrought 316L tested in similarenvironment.31 With the exception of conventionallysintered 434L compacts that had low densification andconsequently exhibit heavy pitting, all others compactsexhibit a non-localised corrosion. Table 4 summarises

Table 4 Passivity parameters obtained for sintered 316L and 434L stainless steels from anodic polarisation study in0?1 N H2SO4: both stainless steel grades were sintered at 1350uC in a conventional as well as microwavefurnace

Stainless steel grade Heating mode Icorr/mA cm22 Icrit/mA cm22 Ecorr/mV Corrosion rate/mm/year

316L CON 0.65 88 2404 63MW 0.71 21 2338 43

434L CON 86.8 410 2462 4016MW 10.8 25 2341 591

4 Comparison of potentiodynamic polarisation curves of conventionally and microwave sintered a 316L and b 434L

stainless steels



the corresponding corrosion parameters. As comparedto conventional sintering, microwave sintered stainlesssteel compacts have superior corrosion resistance. Ascompared to 434L grade, the austenitic grade (316L)stainless steel exhibit lower corrosion rate in 0?1 NH2SO4. It can be inferred that for all compositions, thecorrosion rates are comparable to those of conventionalsintered compacts. This indicates that the nature ofpassive film formation on the surface in microwavesintered compacts is probably not that stable. The Icrit

values indicate the beginning of passive film formation.In this case, samples sintered through microwavesintering have relatively lesser Icrit values as comparedto their counterparts sintered through conventionalroute (Figure 4). It would be interesting to conductsystematic evaluation of the nature of the passive filmformation in microwave sintered stainless steels throughelectrochemical impedance spectroscopy technique.

The microstructures of the corroded stainless steelsare shown in Fig. 5. With the exception of convention-ally sintered 434L compacts, the remaining compactsshow a uniform general corrosion.

ConclusionIn the present study, the effects of conventional andmicrowave heating on densification of 316L and 434Lpowder compacts and their electrochemical propertiesare compared. About 85% reduction of sintering time isobserved in a microwave furnace as compared toconventional furnace heating. The microwave sinteredcompacts in general exhibit higher density and hardnessas compared to their conventionally sintered counter-parts. In addition to this, microwave sintered compactshave a more refined microstructure as compared to their

conventionally sintered counterparts and is attributed tolesser microstructural coarsening during microwavesintering. In general, the microwave sintered samplesresult in nobler Ecorr, greater passivation behaviour anda better corrosion rate than the conventional sintering.

References1. E. Klar and P. Samal: ‘Powder metallurgy stainless steel’; 2007,

Materials Park, OH, ASM International.

2. J. C. Rawers, J. S. Dunning, G. Asai and R. P. Reed:

‘Characterization of stainless steels melted under high nitrogen

pressure’, Metall. Trans. A, 1992, 23A, 2061–2068.

3. J. Rawers, F. Croydon, R. Krabbe and N. Duttlinger: ‘Nitrogen

enhanced stainless steel by PIM’, Int. J. Powder Metall., 1996, 32,

(4), 319.

4. S. S. Panda, V. Singh, A. Upadhyaya and D. Agrawal: ‘Sintering

response of austenitic (316L) and ferritic (434L) stainless steel

consolidated in conventional and microwave furnaces’, Scr.

Mater., 2006, 54, 2179–2183.

5. G. H. Lei, R. M. German and H. S. Nayar: ‘The influence of

sintering variables on the corrosion resistance of 316L stainless

steel’, Powder Metall. Int., 1983, 15, (2), 70–76.

6. M. C. Baran and B. A. Shaw: ‘Corrosion modes in P/M ferritic

stainless steels’, Int. J. Powder Metall., 2000, 36, (4), 57–68.

7. L. Cambal and J. A. Lund: ‘Supersolidus sintering of loose steel

powders’, Int. J. Powder Metall., 1972, 8, (3), 131–140.

8. E. Ahlberg, P. Engdahl and R. Johansson: ‘An electrochemical

investigation of the corrosion behavior of sintered stainless steels’,

Proc. PM World Conf., Shrewsbury, UK, 1990, European Powder

Metallurgy Association, 1990, Vol. 1, 419–432.

9. D. R. Gabe: ‘Corrosion and protection of sintered metal parts’,

Powder Metall., 1977, 20, (4), 227–231.

10. E. Otero, A. Pardo, E. Saenz, M. V. Utrilla and F. J. Perez,

‘Influence of microstructure on the corrosion resistance of AISI

Type 304L and 316L sintered stainless steels exposed to ferric

chloride solution’, Mater. Charact., 1995, 35, 145–151.

11. E. Otero, A. Pardo, E. Saenz, M. V. Utrilla and F. J. Perez:

‘Corrosion resistance of sintered austenitic stainless steels in boiling

nitric acid’, Can. Metall. Q., 1997, 36, (1), 65–72.

5 SEM images of corroded a austenitic and b ferritic grade stainless steels sintered conventionally (left) and in a micro-

wave furnace (right)



12. E. Otero, A. Pardo, E. Saenz, M. V. Utrilla and F. J. Perez:

‘Corrosion behavior of AISI 304L and 316L stainless steels

prepared by powder metallurgy in the presence of sulfuric and

phosphoric acid’, Corros. Sci., 1998, 40, (8), 1421–1434.

13. G. H. Lei, R. M. German and H. S. Nayar: ‘The influence of

sintering variables on the corrosion resistance of 316L stainless

steel’, Powder Metall. Int., 1983, 15, (2), 70–76.

14. C. Garcıa, F. Martin and Y. Blanco: ‘Effect of sintering cooling

rate on corrosion resistance of powder metallurgy austenitic,

ferritic and duplex stainless steels sintered in nitrogen’, Corros. Sci.,

2012, 61, 45–52.

15. W. Fredriksson, D. Petrini, K. Edstrom, F. Bjorefors and L.

Nyholm: ‘Corrosion resistances and passivation of powder

metallurgical and conventionally cast 316L and 2205 stainless

steels’, Corros. Sci., 2013, 67, 268–280.

16. R. Roy, D. Agrawal, J. Cheng and S. Gedevanishvili: ‘Full

sintering of powdered- metal bodies in a microwave field’, Nature,

1999, 399, 668–670.

17. A. J. Sedriks: ‘Effects of alloy composition and microstructure on

the passivity of stainless steels’, Corrosion, 1986, 42, (7), 376–388.

18. J. Cheng, R. Roy and D. Agrawal: ‘Radically different effects on

materials by separated microwave electric and magnetic fields’,

Mater. Res. Innov., 2002, 5, 170–177.

19. N. Yoshikawa, E. Ishizuka and S. Taniguchi: ‘Heating of metal

particles in a single-mode microwave applicator’, Mater. Trans.,

2006, 47, (3), 898–902.

20. K. Saitou: ‘Microwave sintering of iron, cobalt, nickel, copper and

stainless steel powders’, Scr. Mater., 2006, 54, 875–879.

21. A. Al-Tounsi and M. S. J. Hashmi: ‘Effect of sintering temperature

on the densification, shrinkage and compressive strength of

stainless steel 300 series’, J. Mater. Process. Technol., 1993, 37,

551–557.

22. ‘MPIF Standard 35: Materials standard for PM structural parts’,

Standard test methods for metal powders and powder metallurgy

products, Metal Powder Industries Federation, Princeton, NJ,

USA, 1991.

23. S. K. Mukherjee and G. S. Upadhyaya: ‘Sintering of 434L ferritic

stainless steel containing Al2O3 particles’, Int. J. Powder Metall.

Powder Technol., 1983, 19, 289–294.

24. D. Uzunsoy: ‘Investigation of dry sliding wear properties of boron

doped powder metallurgy 316L stainless steel’, Mater. Des., 2010,

31, 3896–3900.

25. W. Jones: ‘Fundamental principles of powder metallurgy’, 399–

407; 1960, London, Edward Arnold Publication.

26. T. Raghu, S. N. Malhotra and P. Ramakrishnan: ‘Corrosion

behaviour of porous sintered type 316L austenitic stainless steels in

3% NaCl solution’, Corrosion, 1989, 45, 689–704.

27. P. Peled and D. Itzhak: ‘Corrosion behaviour of double pressed,

double sintered stainless steel containing noble alloying elements’,

Corros. Sci., 1990, 30, (1), 59–65.

28. D. Itzhak and P. Peled: ‘The effect of Cu addition on the corrosion

behaviour of sintered austenitic stainless steel in H2SO4 environ-

ment’, Corros. Sci., 1986, 26, (1), 49–54.

29. P. Peled, S. Harush and D. Itzhak: ‘The effect of Ni addition on the

corrosion behaviour of sintered austenitic stainless steel in H2SO4

environment’, Corros. Sci., 1988, 28, (4), 327–332.

30. A. Sharon, N. Mclman and D. Itzhak: ‘Corrosion resistance of

sintered stainless steel containing nickel based additives’, Powder

Metall., 1994, 37, (1), 67–71.

31. J. A. Reinshagen and T. J. Brockius: ‘Stainless steel based P/M

alloys with improved corrosion resistance’, in ‘Advances in powder

metallurgy and particulate materials’, (ed. M. Phillips and J.

Porter), Vol. 3, 11?19–11?30; 1995, Princeton, NJ, MPIF.



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