TECHNICAL ARTICLE
Effect of Welding Heat Input on Microstructure and MechanicalProperties of HSLA Steel Joint
Honggang Dong Xiaohu Hao Dewei Deng
Received: 27 November 2013 / Revised: 25 February 2014 / Accepted: 10 March 2014 / Published online: 29 March 2014
Springer Science+Business Media New York and ASM International 2014
Abstract Gas tungsten arc welding of HSLA steel was
conducted with different welding heat inputs, and the
influences of welding heat input on the microstructure,
Vickers hardness, and impact toughness of heat-affected
zone (HAZ) in prepared joints were systematically inves-
tigated. The microstructure in HAZ with low welding heat
input mainly consisted of martensite, and the microhard-
ness of coarse grain HAZ was measured higher than that of
fine grain zone. The results show that increasing the
welding heat input could suppress the formation of mar-
tensite and reduce the microhardness of HAZ. However,
the impact toughness of HAZ was not monotonously
improved with the increase of welding heat input. It is
deemed that the coarsened grain, the formation of upper
bainite, and the non-uniform distribution of carbides and
inclusions in HAZ could degrade the impact toughness.
Tests demonstrate that the optimum comprehensive prop-
erties of HAZ were obtained when the welding heat input
was 0.67 kJ/mm.
Keywords Welding heat input Microstructure Hardness Impact toughness HSLA steel
Introduction
Due to the excellent mechanical properties and weldability,
HSLA steels have been widely used in various fields,
especially in the manufacturing of large-scale naval vessels
and air compressors [1]. As a result, welding of HSLA steels
is indispensable in these large-scale structures. Generally,
high welding heat input is employed because the HSLA
steel structures to be joined usually serve in large size.
However, Viano et al. [2] pointed out that high welding heat
input was often accompanied by wide heat-affected zone
(HAZ), and Li et al. [3] found that the impact toughness of
HAZ was deteriorated when high welding heat input was
applied. So it is necessary to pay more attention to the
influence of welding conditions, especially, the welding
heat input, on the mechanical properties of HAZ.
Extensive investigations have been conducted on the
influence of welding heat input on the microstructure and
mechanical properties of HSLA steel joints. Shome [4]
investigated the relationship between the heat input and the
austenite grain size, and noticed that the prior austenite grain
size was controlled by the peak temperature (Tp) in the
welding thermal cycle which was related to the welding heat
input. Spanos et al. [5] studied the effect of grain size on
hardness, and found that small austenite grain size could
result in higher hardness. Shome and Mohanty [6] also
reported that the toughness decreased with increasing the
austenite grain size. Moreover, Morito et al. [7] revealed that
close relation existed between the strength of lath martensite
in HAZ and the austenite grain size. However, few
researchers comprehensively discussed the relation among
the welding heat input, austenite grain size, hardness, and
impact toughness of HAZ, especially for HSLA steel.
Besides the prior austenite grain size, the properties of
HAZ are heavily dependent on the microstructure which is
determined by the phase transformation after welding. Dhua
et al. [8] found that the welding heat input played a sig-
nificant role in the microstructure of the joints. However,
more attention should be paid to the influence of welding
heat input on the properties of HAZ, as the weakest region,
rather than the weld metal. Mukherjee and Pal [9]
H. Dong (&) X. Hao D. DengSchool of Materials Science and Engineering, Dalian University
of Technology, Dalian 116085, Peoples Republic of China
e-mail: [email protected]
123
Metallogr. Microstruct. Anal. (2014) 3:138146
DOI 10.1007/s13632-014-0130-z
investigated the effect of welding heat input on the micro-
structure and properties of ferritic stainless steel, and they
found that higher welding heat input led to more martensite
and higher toughness. Ion et al. [10] discussed the variation
of the microstructure and hardness of HAZ with the welding
heat inputs, and proposed the HAZ microstructure/hardness
diagrams to guide the welding process. But the impact
toughness of HAZ was not considered which was decisive
for the properties of the joints. Bhadeshia et al. [11] built a
model of the microstructural transformation and believed
that the different phase transformation products were con-
trolled by the cooling rate. Zhang et al. [12] studied the
influence of welding heat input on the toughness of coarse
grain HAZ. They found that when the welding heat input
was increased from 30 to 100 kJ/cm, self-tempered mar-
tensite with fine lath bainite in HAZ transformed to lath
bainite with ferrite, and the impact toughness of coarse
grain heat-affected zone (CGHAZ) decreased. Moreover,
Babu [13] demonstrated that the acicular ferrite produced a
beneficial effect on the properties of the joints. On the other
hand, as indicated by Bhadeshia et al. [11], the formation of
the acicular ferrite was mainly determined by the austenite
grain size, inclusions, and the cooling rate. Also, Lan et al.
[14] found that the medium cooling rate produced larger
volume fraction of acicular ferrite. Bhole et al. [15] reported
that the addition of Mo could promote the formation of
acicular ferrite, and the increase of acicular ferrite led to the
improvement of impact toughness in API HSLA-70 steel.
Furthermore, Harrison and Farrar [16] pointed out that the
high angle grain boundaries responded to the improvement
of impact toughness by acicular ferrite. However, there
were few reports about the formation of acicular ferrite and
the effect of welding heat input on the phase transformation
in HAZ of HSLA steel joints.
In practice, microcracks often initiate in HAZ of the
HSLA steel joints and cause severe economic losses,
especially when the welded structures are subjected to
working conditions with high pressure and large load.
Therefore, more attention should be paid to the properties of
HAZ in HSLA steel joints. In this paper, different welding
heat inputs were applied to gas tungsten arc welding
(GTAW) of HSLA steel plates in order to systematically
investigate the influence of welding heat input on the
microstructure and mechanical properties of HAZ. Sub-
sequent tests and analysis were carried out to explore the
relationship between the welding heat input and the variation
of microstructure, hardness, and impact toughness of HAZ.
Experimental
The nominal composition of the as-rolled HSLA steel is
given in Table 1, and the dimensions of HSLA steel plates
used in this paper are 200 mm 9 100 mm 9 6 mm. The
oxide film on the surface of HSLA steel plate was removed
with stainless steel brush and the grease was cleaned with
acetone. Since the aim of this paper is to investigate the
microstructure and corresponding properties of HAZ in the
joint, the effect of filler metal and groove design was not
considered for simplification, although the accepted sheet
thickness was 6 mm. Automatic autogenous GTAW of
HSLA steel was carried out, as shown in Fig. 1. Argon was
used as the shielding gas with a flow rate of 10 L/min. The
arc length was kept constant at 3 mm, corresponding to the
welding voltage of 11 V. The welding heat input (E) was
calculated with the formula: E = gIU/m, where I, U, v, andg are the welding current, welding voltage, welding speed,and arc efficiency, respectively. Here, the arc efficiency gwas set at 0.7 based on the simulation results by Mousavi
and Miresmaeili [17]. Dt8/5 is commonly used as thecooling rate index to represent the cooling time from 800 to
500 C, and it could be calculated by the empirical equa-tion: Dt8/5 = 5gE [18]. The other welding parameters,resultant welding heat inputs, and Dt8/5 are listed inTable 2. The specimen was etched with 4% nital solution
and microstructure observation was carried out with optical
microscopy (OM). At about 1 mm below the surface of the
weld, Vickers hardness test was conducted on the cross
section of the joints with a load of 300 g for 15 s to obtain
the distribution of microhardness in the HAZ and weld.
The distance between every two adjacent test points was
200 lm. Specimens were extracted by wire cutting forstandard Charpy notch (U-notch) impact test to evaluate
the impact toughness of HAZ. Figure 2 shows the location
Table 1 Nominal compositionof HSLA steel in wt%
C Si Mn Cr Mo Cu S P Fe
0.130.18 0.170.37 0.500.80 2.202.50 0.770.90 \0.30 \0.03 \0.035 Bal.
Fig. 1 Schematic for gas tungsten arc welding of HSLA steel platewithout filler metal. The welding was performed by a travel
mechanism automatically
Metallogr. Microstruct. Anal. (2014) 3:138146 139
123
of U-notch in the joint for impact test. Then the fractured
surface was examined with a scanning electron microscope
(SEM).
Results and Discussion
Microstructure
It can be seen in Fig. 3 that the microstructure of HSLA steel
base metal was typically granular bainite (GB) which con-
sisted of carbides (black) and stripy ferrite (white). The
microstructure of HAZ under welding heat inputs of 0.25 and
0.67 kJ/mm are revealed in Figs. 4 and 5, respectively. The
weld penetration and weld width increase with increasing the
welding heat input, as shown in Table 2 and Figs. 4(a) and
5(a). It was found that the microstructure in fine grain HAZ
(FGHAZ) of HSLA steel mainly consisted of fine grain lower
bainite. Small amount of martensite appeared in FGHAZ
when the welding heat input was 0.25 kJ/mm and it changed
to acicular ferrite and lower bainite after increasing the heat
input to 0.67 kJ/mm. In contrast, the microstructure in
CGHAZ is more complicated.
As reported by Lan et al. [14], lath martensite (M), lath
bainite (B), retained austenite, and various ferrites (F) with
different morphologies could be observed in HAZ of HSLA
steel joints. When different welding heat inputs were used,
the HSLA steel base metal near the fusion line experienced
different thermal cycles, and different microstructures were
formed in HAZ. When the welding heat input was only
0.25 kJ/mm, the cooling time (Dt8/5) was about 0.88 s, andthis fast cooling rate easily produced brittle and hard phases
in HAZ. It can be seen in Fig. 4(b, c) that lath martensite
dominated in the narrow CGHAZ, but lower bainite with a
little martensite formed in FGHAZ. The microstructure in
HAZ with welding heat input of 0.40 kJ/mm consisted of
lath martensite and some bainite, and Dt8/5 was up to 1.4 scorresponding to the increase of heat input. The increase of
Dt8/5 restrained the phase transformation of martensite andproduced some lath bainite in HAZ. This mixed micro-
structure of lath martensite and bainite was similar to that
observed by Shome et al. [19] who believed that martensite
was the main microstructure in HAZ of HSLA-80 steel and
HSLA-100 steel-welded joints. Although martensite could
improve the strength, Thewlis [20] stated that it usually led
to high hardness and was harmful to the impact toughness of
HAZ. And similar conclusions were obtained by Zhang
Fig. 2 Illustration of the location of the U-notch in the joint
Fig. 3 Microstructure of the as-rolled HSLA steel base metal. GBgranular bainite, F ferrite
Table 2 Welding parameters,welding heat input, weld
penetration, weld width, and
Dt8/5 for GTAW of HSLA steel
Sample
no.
Welding
current,
I (A)
Welding
speed,
v (mm/s)
Welding
heat input,
E (kJ/mm)
Weld
penetration
(mm)
Weld
width
(mm)
Dt8/5(s)
1 180 3 0.46 1.8 8.0 1.61
2 220 3 0.57 2.5 11.0 2.00
3 260 3 0.67 2.7 12.3 2.35
4 260 5 0.40 2.2 9.0 1.40
5 260 8 0.25 1.7 7.3 0.88
6 300 3 0.77 2.8 13.4 2.70
140 Metallogr. Microstruct. Anal. (2014) 3:138146
123
et al. [12]. With increasing the welding heat input, the
cooling time Dt8/5 became longer, and the amount of mar-tensite in HAZ decreased accompanied by an opposite
change of bainite. When the welding heat input was
0.67 kJ/mm, the microstructure in HAZ was mainly fine
lower bainite with some acicular ferrite, as shown in
Fig. 5(b, c). In lower bainite, the carbides existed within
and between the ferrites. While Thewlis [21] demonstrated
that in upper bainite, the carbides could only be observed
between the ferrites. In Fig. 5(c), the carbides were refined
further, and the distribution of carbides was more homo-
geneous. Moreover, Lan et al. [14] revealed that the mod-
erate cooling rate was beneficial for the phase
transformation of acicular ferrite. When the welding heat
input was 0.67 kJ/mm, Dt8/5 was about 2.35 s, which pro-moted the formation of acicular ferrite and lower bainite.
The microstructure in CGHAZ under the welding heat
input of 0.77 kJ/mm consisted of lower bainite, small
amount of upper bainite, and coarsened acicular ferrites.
Especially, the grain size in CGHAZ became very large
when the welding heat input was 0.77 kJ/mm, and even
some extraordinary large grains about 250 lm in lengthcould be observed in CGHAZ, as shown in Fig. 6. The
formation of extraordinary large grain could be attributed
to the carbides or other inclusions dissolved under the high
welding heat input, and also the weakened block effect of
second phase particles or inclusions on the grain growth.
The columnar crystal formed in the fusion zone (FZ),
and the microstructure consisted of various ferrites with
carbides. The increase of welding heat input changed the
morphology of ferrite in FZ. In Fig. 4(d), the microstruc-
ture was acicular ferrite (AF) and primary ferrite (PF).
Increasing the welding heat input to 0.67 kJ/mm, primary
ferrite (PF) appeared at the grain boundary. The acicular
ferrite in FZ was coarsened and then ferrite side plate (FS)
formed, as shown in Fig. 5(d).
Furthermore, higher welding heat input also enlarged
the grain size of CGHAZ. It can be seen that the grain size
of CGHAZ under the welding heat input of 0.67 kJ/mm
was larger than that under 0.25 kJ/mm, because higher
welding heat input produced a higher peak temperature in
the welding thermal cycle and promoted the grain growth
in CGHAZ.
The chemical composition and welding thermal cycle
are the most important factors that affect the phase
bFig. 4 Microstructure in HSLA steel joint with welding heat input of0.25 kJ/mm (a) cross section, (b) FGHAZ, (c) CGHAZ, and (d) FZ.B bainite, M martensite, AF acicular ferrite, PF primary ferrite, BM
base metal, FGHAZ fine grain heat-affected zone, CGHAZ coarse
grain heat-affected zone, FZ fusion zone
Metallogr. Microstruct. Anal. (2014) 3:138146 141
123
transformation in HAZ. Based on the formula for calcu-
lating the carbon equivalent recommended by the Inter-
national Institute of Welding [22]: Ceq = C ? Mn/
6 ? (Cu ? Ni)/15 ? (Cr ? Mo ? V)/5, the carbon
equivalent of HSLA steel was about 0.831.05%. Such a
high carbon equivalent could lead to severe harden
quenching tendency and cause the formation of brittle
phases, such as lath martensite. Besides, the heat input
plays a critical role in controlling the microstructure.
Summarizing the above-mentioned description, it reveals
that the welding heat input influenced the microstructure
in HAZ through two aspects. First, the increase of
welding heat input caused the growth of prior austenite
grains and then enlarged the grain size of CGHAZ. Sec-
ond, the welding heat input affected the cooling rate and
then controlled the phase transformation in HAZ. When
the temperature fell into the range of 800500 C afterwelding, the austenite decomposed to different phases.
Babu [13] reported that allotriomorphic ferrite formed
initially at the austenite grain boundary in the high tem-
perature range. With further cooling, acicular ferrite
would nucleate around the inclusions in austenite. While
cooled to lower temperature, the remaining austenite
would transform to bainite and martensite partially or
completely. The cooling rate was very fast when the
welding heat input was lower, and it caused the
bFig. 5 Microstructure in HSLA steel joint with welding heat input of0.67 kJ/mm (a) cross section, (b) FGHAZ, (c) CGHAZ, and (d) FZ.LB lower bainite, FS ferrite side plate, AF acicular ferrite, FS ferrite
side plate, BM base metal, FGHAZ fine grain heat-affected zone,
CGHAZ coarse grain heat-affected zone, FZ fusion zone
Fig. 6 The extraordinary large grain in CGHAZ under welding heatinput of 0.77 kJ/mm. BM base metal, FGHAZ fine grain heat-affected
zone, CGHAZ coarse grain heat-affected zone, FZ fusion zone
142 Metallogr. Microstruct. Anal. (2014) 3:138146
123
martensitic phase transformation. This could be proved by
the microstructure in HAZ with welding heat input of
0.25 kJ/mm as shown in Fig. 4. On the contrary,
increasing the welding heat input to 0.57 or 0.67 kJ/mm,
the corresponded low cooling rate was beneficial for the
formation of bainite. When the welding heat input was
further increased to 0.77 kJ/mm, the ferrite was coarsened
and some upper bainite formed in CGHAZ.
Fig. 7 The distribution of hardness in different zones with welding heat input of (a) 0.25 kJ/mm, (b) 0.40 kJ/mm, (c) 0.46 kJ/mm, (d) 0.57 kJ/mm, (e) 0.67 kJ/mm, and (f) 0.77 kJ/mm. BM base metal, FZ fusion zone, CG coarse grain HAZ, FG fine grain HAZ
Metallogr. Microstruct. Anal. (2014) 3:138146 143
123
Microhardness
The Vickers hardness curves versus different welding heat
inputs are illustrated in Fig. 7, and the average microh-
ardness value in each zone is shown on the top of the figure
for different welding heat inputs. The microhardness in
HAZ and FZ were higher than that in base metal (about
370HV) for all welding heat inputs, but the average hard-
ness changed with the variation of welding heat inputs. The
average hardness of HAZ and FZ with the low heat input
(0.25 kJ/mm) was about 458 and 474 HV, respectively.
However, the average hardness of HAZ with larger heat
inputs (0.570.77 kJ/mm) was relatively lower as around
425 HV.
The microhardness in the HAZ and weld greatly
depended on the microstructure. From the discussion in
Microstructure section, it suggested that the high hard-
ness of the HAZ and weld was attributed to the formation
of lath martensite and bainite, and the decrease of mi-
crohardness was caused by the transformation of micro-
structure. High cooling rate corresponded to the low
welding heat input resulted in the formation of martensite
and increased the microhardness of the HAZ and weld. As
the welding heat input increased, the cooling rate became
slower and martensite disappeared gradually with the for-
mation of bainite. So the average hardness of HAZ was
decreased with increasing the welding heat input due to the
microstructure transformation from martensite to bainite.
In addition, the volume fraction of ferrite enlarged with the
increase of the welding heat input. Arivazhagan et al. [23]
reported that more ferrite would reduce the microhardness.
Moreover, Gharibshahiyan et al. [24] found that the mi-
crohardness also decreased due to the coarsening of grains.
However, Mohandas et al. [25] found a softening zone in
CGHAZ which was opposite to the common observation
and the extent of softening varied with welding methods as
well as the welding heat input.
It was also found that when using lower welding heat
input (0.25 kJ/mm), the average hardness of FGHAZ was
lower than that of CGHAZ, but it was a little higher than that
when higher welding heat inputs (0.67 and 0.77 kJ/mm)
were applied. It revealed that different strengthening
mechanisms affected the microhardness when welded with
different heat inputs. Generally, the microhardness of
FGHAZ was higher than that of CGHAZ due to the fine
grain strengthening. However, the formation of martensite in
CGHAZ under low welding heat input resulted in the higher
hardness than that of FGHAZ in HSLA steel joints.
Impact Toughness
Figure 8 shows the comprehensive variation of the impact
toughness and microhardness in HAZ versus welding heat
inputs. It was found that the impact toughness of HAZ was
higher than that of HSLA steel base metal (107.5 J/cm2),
and it was improved by the increase of welding heat input
accompanied with the decrease of microhardness. The
impact toughness was 182.5 J/cm2 when welded under the
welding heat input of 0.67 kJ/mm and then slightly
declined to 177.5 J/cm2 when the welding heat input was
0.77 kJ/mm. Figure 9 displays the SEM images taken from
the fractured surface. The percentage of shear fracture in
the base metal reached 14%, but that in the rest samples
was around 10%. In Fig. 9(a), river-like patterns could be
seen in the fractured surface on base metal, showing the
feature of quasi-cleavage fracture which was in agreement
with the relatively lower impact toughness of base metal.
However, many dimples could also be found in the frac-
tured surface in Fig. 9(bf), which indicated that the
toughness of HAZ was better than that of base metal. This
phenomenon suggests that within a certain range, the
welding heat input might produce a beneficial effect on the
impact toughness of HAZ in HSLA steel joints.
The effect of welding heat input on the impact toughness
lies in the influence of heat input on the microstructure in
HAZ. When the welding heat input was low, low carbon lath
martensite formed in HAZ, leading to the high microhardness
and low toughness. It is easy for the propagation of micro-
cracks along the parallel martensite lath. With the increase of
welding heat input, martensite transformed to lower bainite
gradually. The carbides distributing within and/or between
ferrites and the interface between martensite and bainite
impeded the propagation of microcracks in lower bainite,
exhibiting better toughness. However, when the heat input
was 0.57 kJ/mm, the toughness of HAZ dropped a little, as
shown in Fig. 8. It could be seen that the size of dimple in
Fig. 8 Vickers hardness and impact toughness versus welding heatinput
144 Metallogr. Microstruct. Anal. (2014) 3:138146
123
Fig. 9(d) was very uneven. It was well known that the dimple
was usually formed where there were inclusions or second
phase particles. Therefore, the drop of impact toughness under
the welding heat input of 0.57 kJ/mm could be attributed to
the dissolution and segregation of inclusions or second phase
particles. The increase of the distance between adjacent
inclusions or particles could reduce the resistance to the
propagation of microcracks, and then decrease the impact
toughness. When the distribution of inclusions was homoge-
neous again, the impact toughness improved, as indicated in
Fig. 8. The microstructure of HAZ with the welding heat
input of 0.67 kJ/mm was fine lower bainite with some acicular
ferrite, which is more difficult for the propagation of micro-
cracks and results in higher impact toughness. However, when
the welding heat input was further increased to 0.77 kJ/mm,
the large grain size of HAZ led to the reduction of total grain
boundary area, and then decreased the impact toughness.
Viano et al. [2] also indicated that high welding heat input
adversely affected the impact toughness of HSLA-80 steel
joint. Besides, the impact toughness was deteriorated due to
the appearance of upper bainite in HAZ, which was in
agreement with the opinion obtained by Abbaszadeh et al.
[26], who reported that the toughness of lower bainite was
much better than that of upper bainite.
As indicated in Fig. 8, the optimum comprehensive
mechanical properties of HAZ in HSLA steel joints were
achieved at a medium welding heat input, 0.67 kJ/mm. The
HAZ welded with the welding heat input of 0.67 kJ/mm
exhibited higher impact toughness (182.5 J/cm2) and lower
microhardness (425 HV). Too low or too high welding heat
input is adverse for the mechanical properties of HAZ.
Conclusions
The effects of welding heat input on the microstructure and
mechanical properties of HAZ in HSLA steel joints were
investigated. Increasing the welding heat input restrained the
formation of martensite and promoted the transformation of
martensite to bainite. When the welding heat input was
0.67 kJ/mm, the microstructure in HAZ was fine lower bainite
with some acicular ferrite. Upper bainite was produced in
HAZ when the welding heat input was 0.77 kJ/mm. The
Vickers hardness of HAZ and FZ of HSLA steel joints was
much higher than that of base metal. The average hardness of
HAZ decreased with increasing the welding heat input. The
hardness of CGHAZ was higher than that of FGHAZ when
using a lower welding heat input. The impact toughness of
HAZ was not monotonously improved with the increase of
welding heat input. The optimum comprehensive properties
of HAZ were obtained when the welding heat input was
0.67 kJ/mm.
Fig. 9 SEM images of the impact fractures in base metal (a) and in HAZ under different welding heat inputs of (b) 0.25 kJ/mm, (c) 0.46 kJ/mm,(d) 0.57 kJ/mm, (e) 0.67 kJ/mm, and (f) 0.77 kJ/mm
Metallogr. Microstruct. Anal. (2014) 3:138146 145
123
Acknowledgments This work was financially supported by theNational Key Basic Research and Development Program of China
(Grant No. 2011CB013402), the National Natural Science Foundation
of China (Grant No. 51374048), and the Fundamental Research Funds
for the Central Universities (Grant No. DUT13ZD209).
References
1. Q. Xue, D. Benson, M.A. Meyers, V.F. Nesterenko, E.A. Olev-
sky, Constitutive response of welded HSLA 100 steel. Mater. Sci.
Eng. A 354(12), 166179 (2003) (in English)2. D.M. Viano, N.U. Ahmed, G.O. Schumann, Influence of heat
input and travel speed on microstructure and mechanical prop-
erties of double tandem submerged arc high strength low alloy
steel weldments. Sci. Technol. Weld. Join. 5(1), 2634 (2000) (inEnglish)
3. Y. Li, D.N. Crowther, M.J.W. Green, P.S. Mitchell, T.N. Baker,
The effect of vanadium and niobium on the properties and
microstructure of the intercritically reheated coarse grained heat
affected zone in low carbon microalloyed steels. Iron Steel Inst.
Jpn. Int. 41(1), 4655 (2001) (in English)4. M. Shome, Effect of heat-input on austenite grain size in the heat-
affected zone of HSLA-100 steel. Mater. Sci. Eng. A 445446(2),454460 (2007) (in English)
5. G. Spanos, D.W. Moon, R.W. Fonda, E.S.K. Menon, A.G. Fox,
Microstructural, compositional, and microhardness variations
across a gas-metal arc weldment made with an ultralow-carbon
consumable. Metall. Mater. Trans. A 32(12), 30433054 (2001)(in English)
6. M. Shome, O.N. Mohanty, Continuous cooling transformation
diagrams applicable to the heat-affected zone of HSLA-80 and
HSLA-100 steels. Metall. Mater. Trans. A 37(7), 21592169(2006) (in English)
7. S. Morito, H. Yoshida, T. Maki, X. Huang, Effect of block size on
the strength of lath martensite in low carbon steels. Mater. Sci.
Eng. A 438440(11), 237240 (2006) (in English)8. S.K. Dhua, D. Mukerjee, D.S. Sarma, Weldability and micro-
structural aspects of shielded metal arc welded HSLA-100 steel
plates. Iron Steel Inst. Jpn. Int 42(3), 290298 (2002) (in English)9. M. Mukherjee, T.K. Pal, Influence of heat input on martensite
formation and impact property of ferriticaustenitic dissimilar
weld metals. J. Mater. Sci. Technol. 28(4), 343352 (2012) (inEnglish)
10. J.C. Ion, K.E. Easterling, M.F. Ashby, A second report on dia-
grams of microstructure and hardness for heat-affected zones in
welds. Acta Metall. 32(11), 19491962 (1984) (in English)11. H.K.D.H. Bhadeshia, L.E. Svensson, B.A. Gretoft, Model for the
development of microstructure in low-alloy steel (FeMnSiC)
weld deposits. Acta Metall. 33(7), 12711283 (1985) (in English)12. Y.Q. Zhang, H.Q. Zhang, J.F. Li, W.M. Liu, Effect of heat input
on microstructure and toughness of coarse grain heat affected
zone in Nb microalloyed HSLA steels. J. Iron. Steel Res. Int.
16(5), 7380 (2009) (in English)13. S.S. Babu, The mechanism of acicular ferrite in weld deposits.
Curr. Opin. Solid State Mater. Sci. 8(34), 267278 (2004) (inEnglish)
14. L.Y. Lan, C.L. Qiu, D.W. Zhao, X.H. Gao, L.X. Du, Effect of
single pass welding heat input on microstructure and hardness of
submerged arc welded high strength low carbon bainitic steel.
Sci. Technol. Weld. Join. 17(7), 564570 (2012) (in English)15. S.D. Bhole, J.B. Nemade, L. Collins, C. Liu, Effect of nickel and
molybdenum additions on weld metal toughness in a submerged
arc welded HSLA line-pipe steel. J. Mater. Process. Technol.
173(1), 92100 (2006) (in English)16. P.L. Harrison, R.A. Farrar, Influence of oxygen-rich inclusions on
the c ? a phase transformation in high-strength low-alloy(HSLA) steel weld metals. J. Mater. Sci. 16(8), 22182226(1981) (in English)
17. S.A.A.A. Mousavi, R. Miresmaeili, Experimental and numerical
analyses of residual stress distributions in TIG welding process
for 304L stainless steel. J. Mater. Process. Technol. 208(13),383394 (2008) (in English)
18. O. Grong, D.K. Matlock, Microstructural development in mild
and low-alloy steel weld metals. Int. Mater. Rev. 31(1), 2748(1986) (in English)
19. M. Shome, O.P. Gupta, O.N. Mohanty, Effect of simulated
thermal cycles on the microstructure of the heat-affected zone in
HSLA-80 and HSLA-100 steel plates. Metall. Mater. Trans. A
35(3), 985996 (2004) (in English)20. G. Thewlis, Weldability of X100 linepipe. Sci. Technol. Weld.
Join. 5(6), 365377 (2000) (in English)21. G. Thewlis, Classification and quantification of microstructures in
steels. Mater. Sci. Technol. 20(2), 143160 (2004) (in English)22. S. Talas, The assessment of carbon equivalent formulas in pre-
dicting the properties of steel weld metals. Mater. Des. 31(5),26492653 (2010) (in English)
23. B. Arivazhagan, G. Srinivasan, S.K. Albert, A.K. Bhaduri, A study
on influence of heat input variation on microstructure of reduced
activation ferritic martensitic steel weld metal produced by GTAW
process. Fusion Eng. Des. 86(23), 192197 (2011) (in English)24. E. Gharibshahiyan, A.H. Raouf, N. Parvin, M. Rahimian, The
effect of microstructure on hardness and toughness of low carbon
welded steel using inert gas welding. Mater. Des. 32(4),20422048 (2011) (in English)
25. T. Mohandas, G. Madhusudan Reddy, B. Satish Kumar, Heat-
affected zone softening in high-strength low-alloy steels.
J. Mater. Process. Technol. 88(13), 284294 (1999) (in English)26. K. Abbaszadeh, H. Saghafian, S. Kheirandish, Effect of bainite
morphology on mechanical properties of the mixed bainite
martensite microstructure in D6AC steel. J. Mater. Sci. Technol.
28(4), 336342 (2012) (in English)
146 Metallogr. Microstruct. Anal. (2014) 3:138146
123
Effect of Welding Heat Input on Microstructure and Mechanical Properties of HSLA Steel JointAbstractIntroductionExperimentalResults and DiscussionMicrostructureMicrohardnessImpact Toughness
ConclusionsAcknowledgmentsReferences
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