The Effect of Carbon on the
Microstructure and Properties of C-Mn
All-Weld Metal Deposits
Carbon promotes acicular ferrite, at the expense of grain
boundary polygonal ferrite, and causes grain refinement of
the reheated regions
BY G. M. EVANS
SYNOPSIS. The effect of 0.05 to 0.15%
carbon on the microstructure and properties of shielded metal arc welds containing 0.6 to 1.8% Mn has been investigated. It was found that carbon promoted acicular ferrite, at the expense of
grain boundary polygonal ferrite, and
caused grain refinement of the reheated
regions. The hardness of the deposits
increased, and the tensile properties
were defined by equations of the form:
a = a + b (C) + c (Mn) 4- d (C • Mn).
With regard to impact properties, it
was found that carbon tilted the CharpyV curves and substantially reduced the
degree of scattering. Optimum toughness was achieved at a manganese level
of 1.4% when the carbon content was in
the intermediate range, i.e., 0.07 to
0.09%.
Introduction
Previous work (Ref. 1), conducted as
part of a joint program within Sub-Commission HA of the International Institute of
Welding, established, for low carbon
deposits, that manganese increasingly
refines weld metal microstructures and
gives rise to optimum impact properties
at a concentration of about 1.5%.
The present work is a continuation of
the program. Its main aim is to ascertain
whether the optimum with regard to
manganese is displaced, depending on
the carbon level of the deposit.
Paper selected as an alternate for the 64th
AWS Annual Convention, Philadelphia, Pennsylvania, April 24-29, 1983.
G. M. EVANS is with Welding Industries Oerlikon Buehrle Ltd., Zurich, Switzerland.
Experimental Procedure
for 14 hours (h).
Electrodes
Low hydrogen, iron powder type elect r o d e s - c o d e d A, B, C and D - w e r e
prepared as in previous work (Ref. 1).
The manganese content of the coverings
was varied to yield deposited metals
containing 0.6, 1.0, 1.4 and 1.8% M n ,
respectively.
At each of these manganese levels
different amounts of graphite were added to the coatings to produce four nominal levels of carbon in the deposited
metals-namely, 0.045, 0.065, 0.095 and
0.145% C. The core wire diameter of the
16 batches of experimental electrodes
thus prepared was 4 mm (0.16 in.), and
the coating factor (D/d) was 1.68.
Weld Preparation
The joint geometry was that specified
in ISO 2560. Welding was done in the flat
position, and three weld beads per layer
were deposited (Ref. 1). The total number of runs required to fill the individual
joints was 27. Direct current (electrode
positive) was employed, the amperage
being 170 A, the voltage 21 V, and the
heat-input was nominally 1 k j / m m (25
kj/in.). The interpass temperature was
standardized at 200°C (392°F).
Mechanical Testing
Two subsize weld metal tensile specimens were machined and tested for each
of the different deposits. Also, approximately 35 Charpy-V notch specimens
were struck to obtain a full transition
curve. The impact specimens were in the
as-welded condition. On the other hand,
the tensile specimens underwent hydrogen removal treatment at 250°C (482°F)
Results
Chemical Composition
The chemical analyses of the weld
metal deposits are given in Table 1. The
compositions were essentially on target,
the nominal values for carbon being
0.045, 0.065, 0.095 and 0.145% at each
of the four manganese levels previously
(Ref. 1) designated as A, B, C and D. The
silicon contents were relatively well balanced, the increase with increasing carbon being slight. Of note is the fact that
both sulfur and phosphorus were low
throughout.
Metallographic Examination
General. Transverse sections were
prepared, and detailed examination was
carried out on the top weld beads and on
the adjacent super critically heat-affected
zones as described previously (Ref. 1).
To illustrate the changes due to carbon, as observed in the light microscope,
typical micrographs for the extremes are
shown in Figs. 1-4 for the 1.4% Mn
level.
As-Deposited Weld Metal. The top
weld bead of each of the test weldments
was examined at the Welding Institute,
U.K., and the microstructural components were quantified according to the
scheme proposed by Abson and Dolby
(Ref. 2) and by Pargeter (Ref. 3).
Point counting was carried out at
X500, and the constituents were identified as follows:
• Grain boundary ferrite.
• Polygonal ferrite.
• Ferrite with aligned M-A-C.
• Acicular ferrite.
WELDING RESEARCH SUPPLEMENT 1313-s
Table 1—Weld Metal Chemical Compositions and Tensile Properties
Tensile properti e s ( a )
Average
Composition,
%
OR,
content, %
designation
C
Mn
Si
S
P
N/mm2*"
N/mm*
EL, %
R.A., %
0.045
A
B
C
D
0.045
0.044
0.044
0.045
0.65
0.98
1.32
1.72
0.30
0.32
0.32
0.30
0.006
0.006
0.006
0.006
0.008
0.008
0.007
0.008
406
432
451
488
462
481
512
549
35.4
35.8
32.0
29.6
78.8
78.8
78.8
76.0
0.065
A
B
C
D
0.059
0.063
0.066
0.070
0.60
1.00
1.35
1.77
0.33
0.35
0.37
0.33
0.007
0.006
0.005
0.006
0,008
0.008
0.007
0.008
407
451
469
511
483
516
545
588
31.2
32.4
29.2
28.4
80.6
80.6
78.8
77.9
0.095
A
B
C
D
0.099
0.098
0.096
0.093
0.65
1.05
1.29
1.65
0.35
0.32
0.30
0.33
0.008
0.007
0.007
0.007
0.009
0.009
0.009
0.007
433
477
506
535
512
546
576
602
31.8
30.0
30.8
27.8
78.8
78.8
77.9
74.0
0.145
A
B
C
D
0.147
0.152
0.148
0.141
0.63
1.00
1.40
1.76
0.40
0.41
0.38
0.36
0.008
0.007
0.007
0.006
0.007
0.007
0.007
0.007
480
517
536
606
569
605
636
691
32.8
27.4
27.4
25.6
76.0
75.0
75.7
71.9
(a) o E = yield stress; <TR = ultimate tensile stress; El. = elongation; R.A. = reduction in area.
(b) psi = 145.0377 X N / m m 2 .
• Ferrite-carbide aggregate.
• Carbide.
The quantitative data obtained are
plotted in Fig. 5; they show that the
amount of grain boundary ferrite and
polygonal ferrite decreased as the carbon
content was increased. In the main, the
change was compensated for by an
increase in the amount of acicular ferrite
rather than an increase in the proportion
of the side plate structures, i.e., ferrite
with M-A-C. The ferrite-carbide aggregate also increased but only at the lowest
levels of manganese.
A visual impression of the microstruc-
'
tural change in the top bead is obtained
from Fig. 1. Here it is seen that the
measured reduction in polygonal ferrite is
reflected in thinner ferrite veins. Of further note is the fact that the columnar
grain width also decreased. This latter
phenomenon is quantified in Fig. 6, the
main variation occurring over the lower
end of the investigated carbon range. An
additional point is that the average grain
width was slightly reduced throughout by
the addition of manganese.
Examination of the acicular ferrite in
Fig. 2 shows changes in the aspect ratio
of the ferrite laths; the structure at the
'.
.
•
higher carbon level is more classically
Widmanstatten in nature. A further
observed difference is in the size of the
microphase regions occurring between
the laths. Subsequent examination in the
scanning electron microscope (SEM) confirmed that amounts of these martensite
/ austenite (M / A) phases increased
substantially as the carbon content was
increased.
Reheated Weld Metal. Studies of the
coarse grained regions also revealed differences in microstructure as exemplified
in Fig. 3. With increasing carbon, the
width of the ferrite envelopes delineating
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Fig. 2 — Photomicrographs of acicular ferrite in
Fig. 1 — Photomicrographs of top beads (co- columnar regions, 1.4% Mn. A—0.045% C; Fig. 3 — Photomicrographs of coarse grained
regions, 1.4% Mn. A-0.045% C; B-0.145%
lumnar), 1.4% Mn. A-0.045% C; B-0.145% B-0.145% C. X100 (reduced 38% on reproduction)
C. X200 (reduced 38% on reproduction)
C. XI00 (reduced 38% on reproduction)
314-s I NOVEMBER 1983
the prior austenite grain boundaries
decreased and thus enhanced the etching
response. The grain interiors transformed
to a fine acicular structure, and the
changes were essentially a reflection of
those occurring in the as-deposited weld
metal.
Comparison of the two photomicrographs in Fig. 4 shows that grain refinement also occurred in the fine grained
reheated regions. The results of linear
intercepts made at X630 are plotted in
Fig. 7. The effects of carbon and manganese were found to be approximately
equivalent over the experimental ranges
investigated. The microstructure became
more duplex with increasing carbon as
shown in Fig. 4, and the second phases
tended to separate, to an increasingly
greater extent, along the primary segregation bands. The form and structure of
the second phase particles were revealed
by deep etching in a mixture of bromine
and methanol, followed by examination
in the SEM at X5000 magnification. The
phases were identified, by the British
Steel Corporation, as:
• Cementite films.
100
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Fig. 4 - Photomicrographs of fine grained
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C. X630 (reduced 38% on reproduction)
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Fig. 5- • Effect of carbon on the microstructure of weld metals obtained using electrodes A, B, C, and D with Mn in coverings varied to yield deposit
metals containing Mn as follows: electrode A-0.6% Mn, electrode B- 1.0% Mn, electrode C-1.4% Mn and electrode D- 1.8% Mn
005
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WELDING RESEARCH SUPPLEMENT 1315-s
• Martensite / austenite (M / A).
• Bainite / Fine pearlite (B / P).
The volume fractions were found to
increase with increasing carbon content
as shown in Figs. 8 and 9 for the 0.6 and
1.4% Mn levels, respectively.
Hardness Testing
Average hardness values, obtained for
ted in Fig. 11; the difference of 30 DPN
(Le., VHN), as encountered for the top
beads, is reflected throughout most of
the weldments.
the last weld bead to be deposited in
each case, are plotted in Fig. 10. The
trends are essentially linear, the increase
over the range for manganese being 50
DPN (i.e., VHN) compared to approximately 30 DPN (i.e., VHN) for the experimental range of carbon contents.
Hardness traverses along the center
line of deposits welded with electrode C,
at the two extremes of carbon, are plot-
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Mechanical Properties
Tensile Results. The tensile test results
are presented in Table 1. The yield
strengths and the ultimate tensile
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different manganese levels as follows: A —0.6%;B— 1.0%, C— 1.4% and
D- 1.8%
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Fig. 7 — Effect of carbon on the grain intercept in the fine grained region
at different manganese levels as follows: A —0.6%, B— 1.0%, C— 1.4%
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316-s | NOVEMBER 1983
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Fig. 9 —Effect of carbon content on percentage microphases in fine
grained regions, 1.4% Mn (cementite films, martensite/austenite,
bainite/pearlite)
strengths are plotted against carbon content in Figs. 12 and 13, respectively. O n
assuming the tensile properties to be
linearly related to both carbon and manganese, the following regressions were
obtained:
1. For yield strength (in N/mm 2 ):
o-E = 335 4- 439 C 4- 60
Mn 4- 361 C • Mn
(1)
2. For ultimate tensile strength (in N /
mm 2 ):
O-R = 379 4- 754 C 4- 63
Mn 4- 337 C • Mn
(2)
Impact Results. Charpy-V impact
curves, obtained from the average of the
scatter bands, are plotted in Fig. 14. It is
seen that the upper shelf was depressed
by the addition of carbon, whereas the
lower shelf tended to be raised.
On reconsidering the absorbed energy
as a function of manganese (Fig. 15), the
optimum composition for the transition
range was found to occur at about 1.4%
Mn, independently of the carbon level of
the deposits.
The relative effects of carbon and
manganese on lateral shift are depicted in
Fig. 16. Here the Charpy-V temperatures
corresponding to an arbitrary level of 100
) are plotted against composition. At the
low manganese level (A), carbon was
found to be marginally beneficial, whereas at the high level (D) carbon was
deleterious. For the intermediate manganese content (C), optimum toughness
was achieved at an intermediate carbon
content of 0.09%. Comparison of the
t w o graphs in Fig. 16 shows, for the
specific ranges, that manganese had a far
greater influence on lateral shift than
carbon.
An additional feature to the tilting of
the average Charpy-V curves was the
observed fact that the degree of scattering decreased as the carbon content
increased. The phenomenon is illustrated
in Fig. 17 for the two extremes of carbon
at the 1.4% Mn level. The situation for the
low carbon level is seen to be undesirable, the transition being extremely steep
and such that full bi-modal fracture
occurred at - 4 0 ° C (-40°F).
Discussion
It is generally accepted (Refs. 4-6) that
the addition of carbon to low strength
ferritic weld metal causes the yield and
tensile strengths to increase and ductility
to decrease. Furthermore, the hardness
increases and, at a constant grain size, the
yield-to-tensile strength ratio decreases.
The role of different alloying elements is
known to be complex; carbon in isolation, for example, behaves differently
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CARBON IN W E L D . \ .
Fig. 10—Effect of carbon on hardness of
as-deposited weld metal at different manganese levels as follows: A—0.6%, B—1.0%,
C-1.4% andD- 1.8%
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Fig. 11.-Effect
B- 1.0%, C-
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TOP S U R F A C E
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manganese levels as follows:
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CARBON IN W E L D , wt.%.
Fig. 12 — Effect of carbon on yield stress at different manganese levels as
follows: A -0.6%, B- 1.0%, C- 1.4% andD1.8%
Fig. 13 —Effect o
manganese levels
D-1.8%
010
CARBON IN
0-15
WELD, wt.%.
carbon on ultimate tensile strength at different
as follows: A —0.6%, B—1.0%, C—1.4% and
WELDING RESEARCH SUPPLEMENT 1317-s
tered when varying the manganese content over the range from 0.6 to 1.8%. On
the other hand, increasing carbon did
lead to the precipitation of increasing
amounts of carbide within the acicular
ferrite.
The microstructure of the reheated
zones was also modified by the addition
of carbon. In the case of the coarse
grained regions, the ferrite envelopes
tended to be eliminated, and in the fine
grained regions the grain size decreased
appreciably. The degree of grain refinement induced by the increase in carbon
was essentially the same as that encountered for the experimental range of manganese contents. As expected, the
amount of second phase carbides in the
fine grained regions increased as the
carbon level was raised.
than when in the presence of manganese, silicon and oxygen (Ref. 7).
The present metallographic studies
have shown that the microstructure of
as-deposited weld metal is modified by
the addition of carbon. O n a macroscale,
the main observation was that the prior
austenite grain width decreased, due
possibly to a change in the solidification
sub-structure. Carbon was more effective in this respect than manganese, and it
is presumed that the relative effects on
dendrite spacing are different.
On a microscale, carbon was found to
increase the amount of acicular ferrite at
the expense of the proeutectoid ferrite
occurring at the boundaries of the columnar grains. For an increment of 0.1% C,
however, the overall change in microstructure was far less than that encoun-
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The tensile properties achieved in the
present instance varied linearly with
respect to both carbon and manganese,
the regression equations being in the
form:
a = a + b (C) 4- c (Mn) 4- d (C • Mn).
Interaction occurred as indicated by
the lines in Figs. 12 and 13 which are not
parallel. This is as expected, since it is
known, for wrought materials, that both
elements have an effect on solid solution
hardening, grain size and the percentage
amount of pearlite (Ref. 8).
The present data serve to confirm the
statement made by Heuschkel (Ref. 9)
that, for all practical purposes, there is
little error in assuming 0.04 to 0.14%
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1
318-s | NOVEMBER 1983
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T E M P E R A T U R E , °C .
carbon increases yield strength in a linear
manner. Straight line relationships have
been obtained previously for manganese, the specific constants being dependent on process variables, such as interpass temperature (Ref. 10) and heat-input
(Ref. 11).
The addition of carbon to the weld
deposits modified the shape of the Charpy-V curves by lowering the upper shelf
energy values and making the transition
between the ductile and the brittle mode
of fracture more gradual. Thus, with
increasing hardenability, the critical inclusion distance decreased and the second
phases increasingly served as sites for
micro-void coalescence.
Allen, et al. (Ref. 12), have suggested
that carbide films contribute to the
change in slope of the transition curves.
Also, den Ouden, ef al. (Ref. 7), proposed
that flattening occurs to a greater extent
when carbon is present together with a
certain amount of oxygen. At the lower
end of the transition range, carbon was
beneficial to an extent that depended on
manganese; also, the detrimental influence of carbides on cleavage (Ref. 12)
was evidently compensated for by the
reduction in grain size. The overall situation was such that the optimum with
regard to manganese remained at
approximately 1.4%, independent of the
carbon content —Fig. 15. This finding is
contrary to that expected and indicates
that dilution with a high carbon base
material cannot be compensated for by
lowering the manganese level.
250
Moll and Stout (Ref. 13) and den O u den, et al. (Ref. 7), have shown that
commercial weldments have comparable
if not better transition characteristics than
deposits synthesized from pure raw
materials. In addition, Sagan and Campbell (Ref. 4) refer to an instance where a
low carbon content is by no means
desirable. In that case, an extra low carbon E7018 electrode, produced with an
ingot-iron core wire, gave a room temperature upper shelf value in excess of
360 | but was inferior to a commercial
product at - 2 0 ° C (-4°F). The requirement, therefore, is for an intermediate
carbon level so that the upper shelf is not
depressed too much while still tilting the
curve sufficiently and limiting the scatter
b a n d - F i g . 17.
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Fig. 15 — Effect of manganese on energy absorbed at different temperatures for different carbon levels
WELDING RESEARCH SUPPLEMENT 1319-s
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0-15
C
D
-30
4 ^ \
Li
' -40
w-50
V.
"
E
z
a
100
-10
UJ
CQ
P
p
<&>
_^-
A.W.
0
LU
Q.
0
-100
S-70
i
l
i
|
-80
-60
-40
-20
t-
- 8 0 CARBON
0065"=
-90
0095%
0-145%
0-5
I
0
I
20
40
0
TEST TEMPERATURE ,°C .
UJ
-100
-20
a
O
co 5 0
<
o
rr
3
<-60
a.
0-147%C
LU
G
t 100 J |
N
AS WELDED
I
l
10
1-5
MANGANESE IN WELD .
Fig. 16 — Effects of carbon and manganese on
test temperatures corresponding to 1001
For E7018 electrodes, w h i c h h a v e
b e e n p e r m i t t e d t o yield u p t o 1.6% M n
since t h e i n t r o d u c t i o n o f A W S A 5 . 1 - 7 8
(Ref. 14), the m o s t suitable range suggeste d by the results of t h e present w o r k is
b e t w e e n a p p r o x i m a t e l y 0.07 and 0.09%
carbon.
Conclusion
For ISO 2560 t y p e d e p o s i t e d m e t a l ,
w e l d e d w i t h basic i r o n p o w d e r elect r o d e s of a specific slag base t y p e , t h e
f o l l o w i n g o c c u r r e d o n increasing the carbon content:
1. T h e average w i d t h of the p r i o r
austenite grains d e c r e a s e d .
2. T h e a m o u n t o f acicular ferrite
increased at t h e expense of the p r o e u t e c t o i d ferrite.
3. T h e aspect ratio of t h e acicular
ferrite c h a n g e d , increasing the a m o u n t of
carbide f o r m e d b e t w e e n the laths.
4. Grain r e f i n e m e n t o c c u r r e d in t h e
high t e m p e r a t u r e r e h e a t e d regions.
5. Grain r e f i n e m e n t o c c u r r e d in t h e
l o w t e m p e r a t u r e r e h e a t e d regions.
6. Increasing
amounts
of
second
phases w e r e precipitated in the fine
grained regions.
7. T h e hardness increased.
8. T h e yield and tensile strengths
increased linearly, b o t h parameters being
d e f i n e d b y equations of the f o r m :
320-s I NOVEMBER 1983
Fig. 17 —Charpy V-notch impact curves showing scatter bands for low and high carbon levels at
1.4% Mn
<J = a 4- b (C) + c ( M n ) + d (C • M n ) .
9. T h e C h a r p y - V curves w e r e tilted,
the u p p e r shelf being depressed w h e r e a s
the l o w e r shelf w a s raised.
10. The d e g r e e of scattering in the
C h a r p y V - n o t c h test w a s r e d u c e d .
1 1 . N o t c h toughness i m p r o v e d at l o w
manganese levels and d e t e r i o r a t e d at
high manganese levels.
12. At an i n t e r m e d i a t e manganese
c o n t e n t (1.4%), the toughness initially
i m p r o v e d a n d t h e n d e t e r i o r a t e d , an o p t i m u m o c c u r r i n g in the range 0.07 t o
0.09% C.
13. At any specific c a r b o n c o n t e n t ,
o p t i m u m toughness w a s e n c o u n t e r e d at
1.4% M n .
Acknowledgments
T h e author wishes t o express his
thanks t o D r . D. ). A b s o n a n d M r . R. J.
Pargeter of the W e l d i n g Institute a n d t o
Dr. R. C. C o c h r a n e of t h e British Steel
C o r p o r a t i o n f o r c o n d u c t i n g most of the
metallographic part of the present w o r k
under contract.
References
I. Evans, C. M. 1980. The effect of manganese on the microstructure and properties of
all-weld-metal deposits.
Welding
journal
59(3):67-s to 75-s.
2. Abson, D. )., and Dolby, R. E. A scheme
for the quantitative description of ferritic weld
metal microstructures. IIW document IX-l-2980.
3. Pargeter, R. |. Quantification of ferritic
weld metal microstructures — results of an
international exercise. IIW document IX-J-3780.
4. Sagen, S. S.. and Campbell, H. C. 1960
(April). Factors which affect low-alloy
weld
metal notch toughness. Welding Research
Council bulletin no. 59.
5. Masubuchi, K., Monroe, R. E., and Martin, D. C. 1966 (lanuary). Interpretive report on
weld-metal
toughness. Welding Research
Council bulletin no. 111.
6. Dorschu, K. E. 1977 (October). Factors
affecting weld metal properties in carbon and
low alloy pressure vessel steels. Welding
Research Council bulletin no. 231.
7. den Ouden, C , Verhagen, |. G., and
Tichelaar, C. W. 1975. Influence of chemical
composition on mild steel weld metal notch
toughness. Welding lournal 54(3):87-s to
94-s.
8. Pickering, F. B. 1978. Physical metallurgy
and the design of steels. Applied Science
Publishers Ltd.
9. Heuschkel, I. 1973. 1972 Adams Lecture:
weld metal property selection and control.
Welding lournal 52(1):1-2 to 25-s.
10. Evans, G. M. 1982. Effect of interpass
temperature on the microstructure and properties of C-Mn all-weld-metal deposits. Welding Review 1(1): 14-20.
11. Evans, C. M. 1982. Effect of heat-input
on the microstructure and properties of C-Mn
all-weld-metal deposits.
Welding
lournal
61(4):125-s to 132-s.
12. Allen, N. P., Rees, W . P., Hopkins, B. E.,
and Tipler, H. R. 1953. Tensile and impact
properties of high-purity iron-carbon-manganese alloys of low carbon content. /. Iron and
Steel Inst. 174:108.
13. Moll, R. A., and Stout, R. D. 1967.
Composition effects in iron-base weld metal.
Welding journal 46(12):551-s to 561-s.
14. American Welding Society. 1978. Specification for carbon steel covered arc welding
electrodes. AWS A5.1-78.