R e s e a r c h
Sponsored by the W e ld ing Research Co unc i l
o f t he En g inee r ing F ound a t ion
S U P P L E M E N T
  TO
  T H E W E L D I N G J O U R N A L , F E B R U A R Y 1 9 7 1
Weldability  of  Constructional Steels-USA Viewpoint
S u b s t a n t i a l p r o g r e s s   has  b e e n m a d e
  in
 t h e  d e v e lo p m e n t
  of
  s t e e l s
s p e c i f i c a l l y  for  w e l d e d f a b r i c a t i o n r a t h e r t h a n d e p e n d in g   on the
e x p a n d e d   use
 of
  s t e e ls c u s t o m a r ily j o i n e d   by  o t h e r m e t h o d s
BY W. D.
than expanding the use of steels joined
by other methods. T he emphasis has been
on strength in combination with ductility,
notch toughness, fatigue strength, corro
sion resistance, and weldability. Of course,
each steel has a different combination of
these properties because the steels differ
in intended application, some being
especially suited for structures and pres
sure vessels at ordinary atmospheric tem
peratures, whereas others are for use at
cryogenic or elevated temperatures. T he
present paper presents the US A view on
the question of whether and to what ex
tent the specification of weldability should
be incorporated in materials specifica
tions.
develop structural and pressure vessel
steels are viewed in the light of fabrica
tion performance and service experience.
Steel producers have taken the lead in the
US A in the development of the weldable
steels and have provid ed sufficient infor
mation from welding tests to enable ap
proval of the steels by specification-writ
ing groups. T his has made it possible for
W.   DOTY   with   Applied Research
Laboratory,  U. S .  Steel  C o r p . ,  Monroeville,
Pa .
Weldability  ot  Structural  and  Pressure
Vessel  S t e e l s organized  by the  Welding
Institute  in  London, England, during  N o
vember 1970;  th e  full Proceedings  of the
Conference will
corporated in materials specifications and
experience does not suggest a need.
Introduction
joining steel. B ut even more signifi
cant, welding is vital as a practical
method for fabricating steel structures
and pressure vessels for modern liv
ing. From this point of view, welding
is as important to a fabricator as
oxygen cutt ing, forming, and machin
ing. However, welding did not gain i ts
present posi t ion as the principal meth
od for joining steel unti l World War II
when greater recognition was given to
the development of steels specifically
for welded fabricat ion rather than de
pending on the expanded use of s teels
customari ly joined by other methods,
such as r ivet ing and b olt ing. A s a
consequence, the past 25 years in the
US A have been a period, s ti ll very
much in progress, in which steel pro
ducers, electrode manufacturers , and
ing procedures .
US A are found in the large family of
weldable construct ional s teels now
available to designers and fabricators.
T he steels rang e in yield point or yield
strength from 30 to  180  ksi (207 to
1241  M N / m
wide range of plate thickness; some
are also available as structural shapes,
pipe, and forgings . T hese steels have
been developed not just because of 
demand for versat i l i ty in s trength, but
because of a demand for steels with
the desired strength in combination
with duct i l i ty, notch toughness, fat igue
strength, corrosion resis tance,
weldabil i ty, al l adequ ate for the in
tended applicat ions .
T he te rm weldab i li ty had no un i
versal ly accepted meaning and the
interpretat ion placed on the term
varies according to individual view
point . However, a widely held view in
the US A is that there are two dist inct
aspects of weldability. T he first is
weldabil i ty during
degree of soundness is obtained.   The
second is weldability for
steel being joined, the application, the
location and design of the weld joint,
the welding process, and the welding
procedu re . T hus, weldabil i ty is not an
intr insic property of a metal .
T he purpo se of this paper is to
present the US A view on the quest ion
of whether and to what extend
  welda-
 
designers and fabricators for use in
general construct ion and pressure ves
sel applicat ions . T able 1 provides a
simplified classification of these steels
based on composit ion type and ther
mal history to show the approximate
range of yield strength (or point)
obtained. T he breadth of the s trength
range for each group is, in general, an
indication of the significance of chem
ical composi t ion and product thick
ness in their effect on strength.
Some representat ive s tructual s teels
and pressure vessel steels with yield
point or yield strength in the range 30
to 180 ksi (207 to 1241 MN /m
2
) are
given in T ables 2 and 3 . T he need for
a multiplicity of weldable steels for
structural and pressure vessel applica
tions stems from the diversity of such
applications, some involving static
some involving operat ion at customary
atmospheric temperatures and others
some requir ing resis tance to abrasion
and others requir ing resis tance to gen
eral corrosion or to various forms of
local ized corrosion.
bon steels generally exhibit ferrite-
pearl i te microstructures and have
minimum yield s trengths in the range,
30 to 50 ks i (207 to 345 M N /m
2
T he effect of increasin g carb on c on
tent in these hot-rolled steels is to
increase the proportion of pearlite in
the microstructure, and thus to in
crease the s trength . However, the use
of such an approach to obtain usable
higher strengths is not feasible for
steels intended for general construc
tional applications because of an asso
ciated decrease in toughness and
weldabil i ty . For example, increasing
the carbon content from 0.2 to 0 .4%
in these hot-rolled steels results in an
increase in yield strength to about 60
k si ( 4 1 3 M N / m
2
t ions .
ble A 373 structu ral carbon steel with
a 32 ks i (221 M N /m
2
structural carbon steel with a 33 ksi
( 2 2 8 M N / m
2
A 373 steel was l imited to 0 . 28 % by
ladle, whereas that for A 7 was unlim
ited, occasionally reaching as high as
0 . 3 5 % .
tinct success from a weld ability view
point .  However,  designers and fabri
cators evidenced only moderate inter
est , because the improvement in weld
abil i ty was accompanied by a reduction
in strength and an increase in steel
cost. Satisfaction was achieved in 1960
with the adoption of  A3 6 structural
carbon steel having a 36 ksi (248
M N / m
carbon content l imit of 0 .29%
(lad le) . T he key to success was a
composit ion with a higher manganese-
carbon rat io to provide a desired com
bination of strength, toughness, and
weldabil i ty .
proach to obtain still higher strengths
in hot rolled steel intended for general
constructional application is to add a
small amount of one or more alloying
elements, such as manganese, s i l icon,
copper, nickel , vanadium, chromiun,
feature of this approach is a low
carbon content — approximately
desired combination of s trength,
toughness, and w eldabil i ty . T he effect
of increasing alloy content in these
low-carbon hot-rolled steels is to
strengthen the ferr i te . Many such
T a b l e   —Classification  of Stri.
C o m p o s i t i o n
t y p e
L o w - A l l o y
11
0
ictural
  a n d P r e s s u r e V e s s e l St e e l s
T h e r m a l h i s t o r y
N o n - h e a t - t r e a t e d
N o r m a l i z e d
Q u e n c h e d a n d T e m p e r e d
N o n - h e a t - t r e a t e d
N o r m a l i z e d
Q u e n c h e d a n d t e m p e r e d
N o r m a l i z e d
N o r m a l i z e d a n d t e m p e r e d
Q u e n c h e d a n d t e m p e r e d
M i n i m u m
y i e l d s t r e n g t h
( o r p o i n t ) ,
k s i
(345-1241)
' 0 .33% max C, C -Mn, C -M n-S i , and C-Mn-S i w i th cer ta in a l lo y ing e lem ent s .
:
  0.25% max C w i th 0.5% or more of Ni , Cr, or Mo.
high-strength low-alloy steels have
balance of composit ion to provide a
desired combination of s trength, notch
toughness, weldabil i ty, and resis tance
to a tmospher ic cor ros ion . T hese pro
prietary steels have been adopted by
A S T M in the speci f ica tions, A 242 ,
A 4 41 ,
  A 5 7 2 , an d A 5 8 8 . T h e d i v er si ty
of composit ions, i l lustrated by the
eight different grades of A 58 8 steel,
offers a fabricator a wide choice in
select ing a grade to provide optimum
weldabil i ty and economy.
Normal ized Steels
steels may reduce strength but will
improve notch toughness when nor
malizin g refines the grain size. T hu s,
the good notch thoughness of normal
ized silicon-aluminum-killed steel is
largely at t r ibutable to the resul tant
fine gra in s ize . A S T M A 537, Grad e
A , steel is an exa mp le of such a
normalized steel . Normalizing such
bility during fabrication, such as sus
ceptibi l i ty to cracking; but normaliz
ing restricts the range of welding proc
esses and procedures which wil l re
sul t in retent ion of adequate notch
toughness for service . T his occurs be
cause retent ion of adequate notch
toughness in the heat-affected zone of
welds is more difficult when judged by
the improved toughness of the nor
malized base metal .
weldable construct ional s teel both
higher strength and sufficient notch
toughness is quenching and tempering.
T his approach resul ts in a micros truc
ture with a high percentage of desir
able low-tem perature t ransfo rmatio n
products and has been the basis for
the development over the past 20 years
of various quenched and tempered
carbon, low-alloy, and alloy steels for
welded construct io n. T he levels of
strength and toughness produced as a
resul t of the heat t reatment depend
upon the specific chemical composi
tion of the steel.
bon steels, enriched with small
amounts of certain al loying elements ,
are A 537 G rade B steel , a pressure
vessel steel with minimum yield
s t rength of 60 ks i (414 M N /
2
) , and
C O N - P A C 8 0, C O N - P A C 9 0 , a nd
C ON -PA C 100 s tee ls wi th min imum
yield strengths of 80, 90, and 100 ksi
( 5 5 2 , 6 2 1 , a n d 6 89 M N / m
2
), respec
tempered carbon steels are also avail
able as abrasion-resistant steel plate
with 285 or 321 min imu m B rinell
hardness .
 
 2—Some
M i n i m u m
yie ld
—
—
—
—
—
(20 @  -6 0° C)
15 @  -5 0° F
(20 @  -4 5° C)
ASTM A36
s t ructures
Ship hul l
Mobi le equipment
Mobi le equipment
Mobi le equipment
and mobi le equip
  H R — h o t - r o l le d ;
  N—normalized; Q&T—quenched
  a n d t e m p e r e d .
h
  M i n i m u m r e q u i r e d v a l u e s u b j e c t t o a g r e e m e n t b e t w e e n s te e l p r o d u c e r a n d u s e r ; v a lu e s h o w n i s t y p i c a l r e q u i r e d m i n i m u m .
U. S. Steel brand name.
d
  S t r e n g t h  r e d u c e d w i t h g r e a t e r t h i c k n e s s .
Quenching and tempering, rather
ty during fabricat ion, but restr icts
weldability for service when the serv
ice requires retention of adequate
notch toughness in the heat-affected
zone of welds . A lso, the higher the
strength of quenched and tempered
carbon steels, the greater the difficulty
of making welds with adequate tensi le
strength, fatigue strength and uni
form bendability, since resistance to
excessive softening is not present in
such carbon steels in that portion of
the weld heat-affected zone subjected
to temperatures just below the lower
transformation temperature of the
velopment of quenched and tempered
alloy steels are the pressu re vessel .
s te e ls : A S T M A 5 3 3 G r ad e B , a
  M n '
strength from 50 to 82.5 ksi (345 to
5 7 0 M N / m
2
) depending on plate
t h ic k n es s ; A S T M A 5 4 2 , a 2 V
4
75 to 100 ksi (517 to 689 M N /m
2
depending on tempering temperature;
A S T M  A 5 4 3 ,  a Ni-C r-M o steel with
minimum yield s trength from 85 to
100 ks i (586 to 689 M N /m
2
) depend
ing on tempering temperature;
A S T M A 517, a mul t ip le -a l loy boron-
containing steel with minimum yield
s t rength of 100 ks i (689 M N /m
2
with minimum yield s trengths of 130
and 180 ks i (896 and 1241 M N /m
2
  A517
A 514, a s tructural-qual i ty plate s teel .
Fur thermore , the  A514/A517  steel is
available in 14 different grades, each
differing in chemical composition.
abrasion-resistant plate steel with 321,
340,  or 360 minimum Brinel l hard
ness . T he diversi ty of comp osit ions of
A514/A517  steel, as with that previ
ously noted for A 588 steel, again
offers a fabricator considerable lati
tude in selecting a grade to provide
optimum weldabil i ty and economy.
T he compo si t ion of quenched and
tempered alloy steels must be shrewd
ly gauged, not only to produce the
desiied
heat-affected zone with the desired
microstructure when this zone is
cooled to room temperature . In this
regard, it is essential to remember that
with increasing section thickeness of
the steel as a plate, structural section,
or forging, a higher hardenability is
required to secure the desired
hardened structure throughout the
mm) and greater produce much faster
cooling rates in the heat-affected zone
during welding than do V
4
  or
2
  in .
thicker sections require compositions
heat t reatment before welding, where
as thinner sect ions require composi
t ions of adequate hardenabil i ty, pr in
cipally for welding.
A design that al lows abrupt changes
in section in a region in high stress is,
unfortunately, too frequently tolerat
ation must also be given to the
  loca-
 
sufficient access for proper
welds are preferable to fillet welds,
first, because the stress-concentration
made butt weld, and second, because
such a weld can be adequately in
spected by radiographic, ul t rasonic,
and magnetic-part icle methods .
bers themselves . This restraint de
pends on the section thickness and the
ar rangement o f the members . A ddi
tional restraint may be introduced by
external devices such as jigs or presses
or by previous welding.
shrinkage during cooling from welding
is such that high tensile stresses are
imposed in the through-thickness di
rection of the structural or pressure
vessel steel being joined and eventual
ly cause separation or lamellar tear
ing. T his undesirable condit ion m ay be
el iminated by changing the locat ion
and design of the joint, by using over
lay welding to local ly improve the
through-thickness propert ies of the
steel, or by replacing the adversely
stressed member with an insert of
forged or specially processed steel.
Selection of WeldJng Process
esses are the arc-welding processes:
shielded metal-arc welding, sub
slag welding processes are also gaining
wide acceptance .
  all
yield strengths to 100 ksi (689
M N /
shielded metal-arc process, noted for
its versatility, currently can be used
effectively for steels with yield
strengths up to about 150 ksi (1034
M N / m
welding of HY-130 steel are in prog
ress. However, the gas shielded-arc
processes, including special modifica
mum yield s trengths greater than 100
k si (6 8 9 M N /
2
arc or the electron-beam welding proc
esses must be used for steels with
yield strengths over 150 ksi (1034
M N / m
T he cooling rates for the electrogas
and electroslag welding processes,
arc-welding processes, are so slow that
the mechanical properties of the weld-
heat-affected zone of electrogas- or
electroslag-welded steels approach
those of the steel in the hot-rolled
cond ition. T hu s, if the steel is welde d
in the normalized or the quenched and
tempered condit ion, then such steel
general ly requires a reheat t reatment
after welding.
electrodes at the end of World War II
was a noteworthy st imulant in the
US A to the development of a large
family of weldable constructional
with the shielded metal-arc, sub
merged arc, and gas metal-arc proc
esses are readily available for all
steels with minimum yield strengths up
to about 120 ksi (827 M N /m
2
t ion by steel producers . Development
of filler metals for steels with mini
mum yield strengths of 130 ksi (896
M N / m
the selection and care of electrodes is
that hydrogen, unwanted in the weld
ing of many types of steels because
hydrogen can cause cracking, is al
ways present and must be kept to a
tolerable amo unt . T he source of hy
drogen can be:
bonded water , and absorbed water in
the electrode covering or welding flux.
2.   Hydrogen in contaminants on
the surface of core wire in covered
electrodes and on the surface of filler
metal, or moisture in shielding gas.
3.   M oisture on the steel surface at
the location of welding.
ceeding about
2
) mini
welded with very simple procedures
using non-low-hydrogen electrodes
and l i t t le or no preheat . For thicker
plates, the preheat is increased.
Low-hydrogen electrodes with a
0.6% are used in welding the steels
with somewhat higher carbon content
and minimum yield s trength (or
point) not exceeding about 60 ksi
( 4 1 4 M N /
2
not used for thin plates but is used for
thick plates . Low-hydrogen electrodes
than 0 .2% are used in welding the
heat-treated carbon, low-alloy, and al
loy steels with a m inim um yield
strength not exceeding about 120 ksi
( 8 2 7 M N / m
2
thin plates of some of these steels, and
for thick plates of all of these steels.
Low-hydrogen electrodes with a
0 . 1 %  are used in welding the HY-130
steel. A p rehe at is used for plates of
nearly all thicknesses of this steel.
T he low-hydrogen ch aracteris t ic of
wire electrodes for submerged arc
welding and of electrodes for flux-
cored arc or gas metal-arc welding is
similar in importance to that discussed
for covered electrodes for shielded
metal-arc welding. For example, the
total hydrogen content of bare wire
electrodes, including the hydrogen
should not exceed 5 ppm for elec
trodes used to weld such steels as
A 5 1 7 ,
  A 5 4 2 , a n d  A 5 4 3 ,  and should
not exceed 3 ppm for electrodes used
to
quate s trength and toughness in the
weld-heat-affected zone has received
weldable constructional steels, espe
imum cooling rate required to pro
duce the desired microstructures, so
essential to achieving adequate
heat-affected zone, will vary, of
course, with the particular steel being
welded. Th us, the proced ure for weld
ing some constructional steels includes
suggested heat-input limits to assure
adequate cooling rates in the  weld-
hsat-affected zone. Such heat- input
limits also benefit the weld metal by
discouraging the deposition of large
weld beads having characteristically
Steel Inst i tute , have been conducted
to define the composition limits for
susceptibility of steels to hot cracking
and cold cracking from welding. Hot
cracking in the heat-affected zone oc
curs at a high temperature, usual ly
just below the sol idus temperature,
whereas cold cracking or delayed
cracking occurs below the  M
a
zone to hot cracking is highly depend
ent on carbon, manganese, and sul
fur content . Weldable s tructural-
quali ty s teels are customari ly pro
duced in the US A with a sulfur con-
 
vessel-quality steels are usually pro
duced with a sulfur content less than
0 .025%, and some, such as HY-130
and HP  9-4-20  steels, are produced
with a sulfur content not exceeding
0 . 010 % . T he manganese to su lfur ra
tio is generally greater than 30, so
that with a carbon content of about
0.20% or less, the susceptibility to hot
crack ing is negligible. T he susceptibili
ty is also negligible for higher carbon
steels with a M n /S rat io greater than
about 40.
straint decreases with increased  M
s
tributed to the self-tempering of the
martensi te that formed at high M
s
cracking is proport ional to the hydro
gen content of the welding atmos
phere .
pressure vessel steels have a negligible
susceptibility to cold cracking pro
vided suitable care is taken to limit
hydrogen in the welding atmosphere
to a tolerable amount . However, the
steels differ somewhat in the amount
of hydrogen tolerated, depending on
the carbon equivalent (C E) as calcu
lated by the following expression,
which, to date, is applicable to steels
having the indicated composit ion l im
its:
10
(0 .30% max C , 1.4% max Mn, 0 .25%
max S i , 3 .6% m ax Ni, 1.8% m ax C r,
0 .5%  max Mo, 0 .1 % max V, 0 .7%
max Cu)
phere depends on the welding process
and the welding procedure, especially
that port ion of the procedure con
cerned with the selection and care of
electrodes. For each higher level of
hydrogen in the welding atmosphere,
the critical weld restraint for initiation
of heat-affected zone cracking de
creases as the carbon equivalent of the
steel increases . T he carbon-equivalent
expression is a research tool, not a
specification index of weldability.
T a b l e 3—Some R e p r e s e n t a t iv e P r e s s u r e V e s s e l S t e e ls
Min imum
yie ld
o r p o i n t ,
si  (MN/m
85
85
85
100
130
180
(586)
(586)
(586)
(689)
(896)
(1241)
C o m p o s i t i o n t y p e
l
0 .28 max C
0 .25 max C-Mo
0.17 max  C-3-J^Ni
0.28 max  C-Mn-Si
0.20 max  C-Mn-Si
0 .2 5 m a x C - M n - M o
0 . 2 5 m a x C - M n - N i -
M o
0.20 max  C-Mn-Si
0 . 2 5 m a x C - M n - N i -
M o
0.15  maxC-2J4Cr-
M o
0.13  maxC-9Ni
0 . 2 0 m a x C - M n - N i -
C r - M o - V - C u - B
0.12 max C-5Ni -
0 . 2 3 m a x C - 9 N i -
4 C o - C r - M o - V
C o n d i
t i o n
r a n g e ,
i n .  ( m m )
a b s o r p t i o n
b
,
—
—
—
15 @ - 9 0 ° F
25  @,  - 8 5 ° F
35 @  10° F
35 @  10° F
50  @ 0° F
o t c h e n e r g y
f t - l b   ( joules)
—
—
(20 @ - 2 9 ° C)
15 @ - 7 5 ° F
—
(0 .381 @
(0.381®
(6 8 @  - 1 8 ° C )
S t e e l
d e s i g n a t i o n
ASTM A285,
Gr. C
ASTM A515,
Gr. 60
ASTM A204,
Gr. A
ASTM A203,
Gr. D
ASTM A516,
Gr. 70
ASTM A537,
PAC)«
ASTM A537,
PAC)=
ASTM A542,
T y p i c a l
a p p l i c a t i o n
G e n e r a l
E l e v . t e m p e r
a t u r e
E l e v . t e m p e r
a t u r e
L o w t e m p e r
a t u r e
G e n e r a l a n d
l o w t e m p e r
a t u r e
G e n e r a l a n d
l o w t e m p e r
a t u r e
G e n e r a l a n d
e l e v . t e m p
e r a t u r e
N u c l e a r
r e a c t o r
G e n e r a l a n d
l o w t e m p e r
a t u r e
L o w t e m p e r
a t u r e
H y d r o - c r a c k e r s
N u c l e a r r e a c t o r
a n d h y d r o -
s p a c e
C r y o g e n i c
L P G a n d  p e n
s t o c k
H y d r o s p a c e
a n d a e r o
s p a c e
H y d r o s p a c e
a n d a e r o
s p a c e
* H R — h o t - r o l l e d ;  Q&T—quenched  a n d t e m p e r e d .
b
  Min imu m req u i re d va lue sub jec t to agree men t be tween s tee l p rodu cer and use r ; va lue shown i s t yp ica l requ i red
  minh
c
d
  S t r e n g t h r e d u c e d w i t h g r e a t e r t h i c k n e s s .
e
  15 mi ls (0 .381 mm ) la te ra l exp ans ion .
' Repub l i c S tee l b rand name.
W E L D I N G R E S E A R C H
  S U P P L E M E N T
53-s
a postweld heat t reatment above
cracking may sometimes occur in the
grain-coarsened region of the weld-
heat-affected zon e. Th e interg ranular
cracking occurs by stress rupture, usu
ally in the early stage of the stress-
relief treatm ent. T hose alloying ele
ments that contribute most significant
ly to the attainment of high strength
and notch toughness in quenched and
tempered alloy steels for welded con
struction are usually the alloy ele
ments that have an adverse effect
when such welded steels are postweld
hea t t rea ted . C hromiu m, molyb
denum, and vanadium are major con
tributors to this crack susceptiblity,
but other carbide-forming elements
during the elevated-temperature s tress
relaxation alters the delicate balance
between resis tance to grain-boundarv
sliding and resistance to deformation
within the coarsened grains of the
weld-heat-affected zone . T hu s, stress-
rupture cracking may occur at the
toes of welds in such steels as A S T M
A542and  A 5 1 7 .
C racking has been prevented by
properly contouring the welds to mini
mize points of stress concentrations by
psening
depositing weld metal having elevated
temperature strength significantly low
zone of the steel during the stress-
rel ief t reatment . However, the need
for such a postweld heat t reatment
should be thoroughly established for
each steel and applicat ion. Many of
the weldable constructional steels are
designed to be used in the less costly
as-welded condition when possible.
Retention of Tensile Strength ,
with hot-rolled steels and normalized
steels. In quenched and tempered alloy
steel with adequate resistance to
softening, 100% joint efficiency at the
desired high strength can be readily
obtained if uncommonly high heat
inputs in welding are avoided. Howev
er , quenched and tempered carbon
steel with a minimum yield strength in
excess of 80 ksi (552 M N /m
2
) re
heat-affected zon e of welds. A needed
restriction on the upper limit of the
welding heat input may el iminate use
of submerged arc welding.
fillet-welded joints in lower strength
hot rolled or normalized steels and on
such joints in the weldable quenched
and tempered steels have shown no
special sensitivity of the heat-affected
zone or weld metal to fatigue
provided, of course, that the steel has
adequate resistance to softening in the
heat-affected zone, as previously dis
cussed, and provided that the weld
metal has adequate tensile strength.
However, the effect of welding on
fatigue must be carefully considered
in regard to geometry, including
soundness, since easy paths of fatigue-
crack initiation are associated with
geometric discontinuities or stress
consideration has been given to the
retent ion of adequate notch toughness
in the heat-affected zone of welds.
T oo often, steels having excellent
toughness in the unaffected base metal
have inadequate heat-affected zone
of the steel. T o ensure tha t this does
not occur, much care has been given
to the composit ion l imits and recom
mended welding procedures for many
of the structural and pressure vessel
steels.
ness in the heat-affected zone of the
heat-t*eated constructional steels de
pends on the rapid dissipation of weld
ing heat to permit the formation of
the microstructures so essential to
achieving the desired notch toughness
in the steel . T o assure adequate notch
toughness, limits are placed on the
maximum welding heat input when
welding by the shielded metal-arc,
submerged arc, flux cored arc, and gas
metal-arc processes . Other processes,
welding, that provide very high heat
input have very limited application for
the normalized steels and no applica
t ion for the quenched and tempered
steels  unless a reheat t reatmen t of the
steels is practical.
For some applications, such as the
p r op o s ed u s e o f A S T M A 5 3 7 , G r a d e
B steel for the hull of polar iceb reak
ers,
this s teel is reduced to 0 .16 % (ma x
imum) and the l imit on manganese
content is increased to 1 .50% (ma x
imum). Such a modified composit ion
provides greater potential in this
quenched and tempered carbon steel
for the attainment of enhanced notch
toughness in the heat-affected zone of
welds exposed to an extreme arctic
tempera ture .
metal and heat-affected zone tough
ness;
pends on chemical composit ion, t reat
ment temperature, and t ime at temper
ature, and is greater with slow cooling
as in s tress rel ieving. T he impa irment
in toughness is at t r ibuted to embri t t le
ment occurr ing on holding at the
stress-relief temperature and to tem
per embri t t lement .
Corrosion Resistance
T h e A S T M A 2 4 2 a n d A 5 8 8 st ee ls
have atmospheric corrosion resis tance
at least 4 times that of carbon struc
tural s teel without copper and are
used principally for structural applica
t ions requir ing durabil i ty, minimum
maintenance, and reduced weight .
the bare condition to provide a de
sired appearance af ter weathering or
to provide savings in maintenance.
For welded joints in such steels for
bare applications, the welding is done
with electrodes that provide weld met
al of adequate alloy content so that
the weld has an appearance, after
weathering, similar to that of the bare
steel.
R esistance to  s t r e s s - c o r r o s i on
cracking, always a desirable property
for most materials , is of paramount
importance in certain applicat ions .
For example, field trials with welded
structural and pressure vessel steels
support the observat ion long recog
nized in the oil industry that steel, at a
hardness of about R ockwell C 22 or
greater, may be suceptible to stress-
corrosion cracking in environments
have, as a result of welding, a hard
ness greater than R ockwell C 22. F or
some s tee ls , such as A S T M A 517
steel , the maximum hardness of the
steel , unwelded, is about R ockwell
C 2 8 .
weldable constructional steels for oil
s torage tanks, marine oi l tankers, and
pipe lines may result in stress corro
sion, particularly in the heat-affected
zone of welds, if the environment
contains hydrogen sulf ide . T he previ
ously mentioned modification of
A S T M A 5 3 7 G r a d e B s te el w i t h
0 .16% maximum carbon and 1 .50%
maximum manganese offers promise
22 in the weld-heat-affected zone.
Specification of Weldability
chemical composition of steel on its
metal lurgical response to the thermal
cycle from welding, as well as to that
from oxygen cutt ing and arc cut t ing,
 
development of modern steels for
welded structures and pressure ves
sels. However, it is always necessary in
the development of such steels to do
extensive testing to ensure that the
heat-affected zone structures, together
properties that result in welded joints
adequate for the intended applicat ion.
In some instances, steels have been
developed that would be attractive for
structural and pressure vessel applica
tion, but the use of the steel has been
greatly restricted by the unavailability
of suitable weld metals. In other in
stances, the use of steels has been
restricted by the availability of only a
single welding process, which may be
economical ly impract ical . This experi
ence has emphasized the need for
Descr ipt ion and Appl icat ion
U S S C O R - T E N B st ee l p r ov i de s
50 ,000 ps i min imum yie ld po in t in
p la tes , bars , and s t ruc tura l shapes
throu gh 4 in . th ick for a wide var ie ty
of app l ica t ions .
For in format ion on typ ica l eng ineer
ing proper t ies and formabi l i ty , see
back cover .
Corrosion Resis tance
C O R - T E N B s t ee l h a s 4 t i m e s th e
a tmospher ic cor ros ion res i s tance of
s t ru c tur a l ca rbon s tee l . B ecause of
t h i s g r e a t e r r e s i s t a n c e t o a t m o s
pher ic cor ros ion , pa in t and o ther
pro tec t ive coa t ings wi l l l as t longer
o n C O R - T E N B s te e l t h a n o n c a r
bon steel .
W e l d a b i l i t y
C O R - T E N B s t ee l c an b e w e l de d ,
using good shop or f ield pract ice, by
a l l u s u a l m e t h o d s : s h i e l d e d m e t a l -
arc,  submerged-arc, f lux-cored arc,
g a s m e t a l - a r c , a n d r e s i s t a n c e
weld ing .
G a s C u t t i n g
C O R - T E N B s t e el c a n b e g a s c u t
using good shop or f ield pract ices in
accordance wi th those sugges ted in
t h e A W S H a n d b o o k . S o m e d e gr e e of
preh ea t in g i s requ i red for gas cu t
t ing . I t is sugges ted th a t p reh ea t
tempera tures l i s ted in the weld ing
tab le be used .
U SS C O R - T E N B C h e m i ca l C o m p o s i t io n * , p e r c e n t ( L a d l e )
C
Mn
*F ine -g ra in p rac t i ce
USS COR-TEN
 M e c h a n ic a l
  P r o p e r t i e s — P l a t e s , B a r s ,
  S t r u c t u r a l s
i
Thickness
incl;  Structurals
in ASTM
50,000
70,000
21*
19
Structurals
-
Spec i f ied min imum y ie ld po in t and tens i le s t reng th sha l l be reduced by  5,000  psi for
any annea led o r norm a l i zed p rodu c ts .
'Elongation  i n 2 in . fo r WF shapes over 426 lb / f t i s 19 percen t m in i m um .
Tes t spec imens , bend tes t requ i rements , p rocedures , and e longa t ion mod i f i ca t ions
con fo rm to ASTM spec i f i ca t ions .
Speci f ica t ions— USS  COR-TEN B s tee l can be p roduc ed to the re qu i r eme nts o f
ASTM sp ec i f i ca t ions A5 88 Grade A o r A242 Type 2 when so o rdere d .
U SS C O R -T E N B S u g g e s t e d W e l d i n g P r a c ti ce s
Electrode
F or g e n e r a l s t r u c t u r a l a p p l i ca t i o n s :
AWS A5.1 low-hydrogen type mild-steel covered elec
trodes (E7016, E7018 or E7028) or
AWS A5.17 mild-steel bare electrodes and fluxes
AWS A5.18 mild-steel bare electrodes and gases
AWS A5.20 mild-steel flux-cored electrodes
F o r b a r e s t e e l a p p l i c a t i o n s :
SINGLE-PASS WELDS may be made using mild steel
w elding m aterials above, provided procedure used
insures suitable composition enrichment.
A5.5 E80XX  - B l ,  -B2, -CI ,  -C2, -C3, or G* low-
hydrogen-type low-alloy steel electrodes
for shielded m etal-arc w elding, or an electrode or
electrode-flux combination for submerged-arc,
provides filler metal similar to that of the above-
mentioned electrodes for shielded metal-arc; these
filler metals for multiple-pass welds may also be used
for single-pass w elds; also, multiple-pass w elds may be
partia lly made w ith m ild steel electrodes and
completed w ith alloy steel electrodes.
Thickness
in.,
  incl
Tol
Fig.  1-
*Weld depos i t , %: O.IO  max C, 0 .50 /0 .90 Mn , 0 .03 max P , 0 .04 max S , 0.35/0.80  Si,
0 . 3 0 / 0 . 7 5 C u , 0 . 4 0 / 0 . 7 0 N i , a n d 0 . 4 5 / 0 . 9 0 C r .
N o t e
 
—Preheat  t e m p e r a t u r e s a b o v e t h e m i n i m u m s h o w n m a y b e r e q u i r e d f o r
h igh ly res t ra ined w e lds . For such w e lds , temp era tu res as h igh as 250 to 40 0 F may
be necessary .
N o t e  2—No  w e l d i n g s h o u ld b e d o n e w h e n a m b i e n t t e m p e r a t u r e is b e lo w  O F. If ste el
tem per a tu re i s be low 50 F, p reh eat ing to 50 F m in i mu m or to ind ica ted p reheat
  t e m
pera tu re , w h ichever i s h igher , shou ld be per fo rm ed.
N o t e  3—Low-hydrogen  e lec t rodes fo r man ua l -a r c w e ld in g , as w e l l as f luxes fo r sub
merge d-a rc w e ld ing and gases fo r gas meta l -a rc w e ld ing , mus t be p roper ly d ry .
- E x c e r p t f r o m p r o p e r t i e s c a r d f o r U S S C O R - T E N s t e e l s h o w i n g s u g g e s t e d w e l d i n g p r a c t i c e s
 
welding-electrode producers , and
welding-equipment manufacturers in
steels, weld metals, and welding proc
esses for welded construct ion. T he
success of this approach is demon
strated by the recent developments in
the US A of weldable construct ional
steels for hydro- and aerospace appli
cat ions .
extensive use is made of beadweld
underbead-cracking tests, fillet-weld
U SS T - 1 S t e e l s P h y s i c a l P r o p e r t i e s
Density,
  Ib/cu
  in.
  the range o f - 5 0 to +1 50 F
0.2833
18
s
USS T-1
Steels—Typical
  E n g i ne e r i n g P r o p e r t i e s
Shear Strength
Approx. 58% of tensi le yield
Approx .
  75 %
Approx. 50% of tensi le ul t imate
D r o p - W e i g h t T e s t , N D T
Steel
- 5
- 5 to - 6 0
Tr ac t u re-transit ton-el a stic
  t e m p e r a t u r e .
tSingle Test Results
H e a t T r e a t m e n t
U S S T - 1 C o n s t r u c t io n a l A l lo y
S tee l s a re normal ly wate r quenched
f rom 16 50/1750 F , and temp ered
a t 1 1 0 0 / 1 2 7 5 F .
C o r r o s i o n R e s i s t a n c e
A tmo sphe r ic cor ros ion res i s tance of
U S S T - 1 S t e e l i s 4 t i m e s t h a t of
s t r u c t u r a l c a r b o n s t e el , a n d T - 1
t y p e A S t e el a n d T - 1 t y p e B
S tee l a re about twice tha t o f ca r
bon s tee l . Spec i fy ing of 0 .20 /0 .40
c o p p e r w i l l i n c r e a s e a t m o s p h e r i c
c o r ro s i o n r e s i s t a n c e of T - 1 t y p e s
A o r B t o a p p r o x i m a t e l y t h r e e t i m e s
tha t o f s t ruc tura l ca rbon s tee l .
W e l d a b i l i t y
U S S T - 1 S t e el s c a n b e w e l de d
sa t i s fac tor i ly by a l l ma jor weld in g
processes when proper p rocedures
are used . (A boo kle t and weld in g
c a l c u l a t o r , H o w t o W e l d U S S   T - 1 '
C o n s t r u c t i o n a l A l lo y S t e e l s , is
a v a i l a b l e f r o m y o u r n e a r e s t U . S .
S teel S ales Office.)
G a s C u t t i n g
T - 1 S tee l s can be gas cu t us ing
good shop or f ield pract ices in ac
cordance wi th those sugges ted in
t h e A W S H a n d b o o k . C u t t i n g of t h i s
ma ter ia l genera l ly does no t requ i re
prehea t ing in th icknesses up to and
inc lud ing 4 in . , bu t the s tee l t em
p e r a t u r e s h o u l d n o t b e l o w e r t h a n
50 F dur ing cu t t ing . For th icknesses
o v e r 4 i n . , p r e h e a t t e m p e r a t u r e s b e
tween 300 F and 400 F (no t h igher )
a r e s u g g e s t e d .
F o r m a b i l i t y
U S S T - 1 S t e e l s c a n b e c o ld
f o r m e d . H o w e v e r , s u i t a b l e b e n d i n g
rad i i and increased power has to be
e m p l o y e d b e c a u s e o f t h e h i g h e r
s t r e n g t h of T - 1 S t e el s c o m p a r e d
to tha t o f s t ruc tura l ca rbon s tee l a t
t h e s a m e t e m p e r a t u r e . S u g g e s t e d
m i n i m u m b e n d i n g r a d i i  are  given
i n t h e a c c o m p a n y i n g t a b l e .
For b rake press fo rming the lower
d ie span should be a t l eas t 16 t imes
t h e p l a t e t h i c k n e s s .
B H N P l a t e s : m o d e r a t e b e n d i n g ca n
be accompl i shed on p la tes t rea ted
t o 3 2 1 , 3 4 0 o r 3 6 0 m i n i m u m B H N
by us ing a rad ius o f  lOt  or g rea te r .
Such forming should pre fe rab ly be
done transverse to the f inal rol l ing
di rec t ion .
Fig.  2—Excerpt  from propert ies card for USS T - 1 cons tructional al loy steels show ing suggested w elding practices
S u g g e s t e d W e l d i n g P r a c tic e s f or T - 1 S t e e ls
(See also How to Weld USS 'T-1'Constructional Alloy Steels, U nited States Steel Corporat ion, latest edi t ion.)
Welding Process
E11018-M per AWS A5.5-64T; lower strength low -hydrogen electrodes, depending
on design stress, may also be suitable
  if
  dried to mo isture leve l of El 1018 elec trode;
a higher strength electrode, such as E12018-M may be necessary for thin plates of
T - 1 type A Steel.
Mn-Ni-Cr-Mo
  w ire and neutral f lux ( for example, t inde 100
 wire
 wire
 and al loy f lux ( for example, Lincoln L61 w ire and A1010 x 10 f lux );
w ire- f lux combinat ions deposit ing lower strength f i l ler metal may also be sui table,
depending on design stress.
Mn-N i -Cr -Mo
  and argon-02 gas ( for example, Airco AX-110, Linde 120, or
Arcosarc HOT).
Plate Thickness,
Over
 2
Shielded
50+
200
300
400
*A   preheat temperature  a b o v e t h e m i n i m u m s h o w n m a y b e  required  f o r h i g h l y  restrained  w e l d s ;
t o w - h y d r o g e n e l e c t r o d e s f o r s h i e l d e d m e t a l - a r c w e l d i n g , a s
  well
  a s f l u x e s f o r s u b m e r g e d - a r c
w e l d i n g a n d g a s e s f o r g a s - m e t a l - a r c w e l d i n g , m u s t b e p r o p e r l y d r y .
t/Welding  a t a n y i n i t i a l t e m p e r a t u r e b e l o w
  IOO
  F w i l l r e q u i r e e x t r e m e c a re to m i n i m i z e m o i s t u r e
o n t h e s t e e l b e i n g w e l d e d .
M a x i m u m H e a t  I n p u t :  Per  t a b l e f o r  T - 1 S t e e l a n d t a b l e f o r   T - 1 t y p e A a n d B S t e e l s in H o w
t o W e l d U S S ' T - 1 ' C o n s t r u c t i o n a l A l l o y S t e e l s , U n i t e d S t a t e s S t e e l C o r p o r a t i o n , l a te s t e d i t i o n .
USS T-1 S t e e l s   180°Cold BendTesr-Plates ASTM  A 5 1 4 a n d A 5 1 7 )
Thickness in. , incl
to Thickness of Specimen
2
3
4
 
specific welding procedures, the suscep
tibility of steels to cracking . T o deter
mine the propert ies of the heat-
affected zone of a weld as influenced
by changes in preheat and heat input ,
use is made of steel specimens subject
ed to a simulated weld thermal cycle
and tested as C harpy V-no tch im pact
specimens or tension specimens. T o
determine the propert ies of welded
joints, use is made of transversely
welded tension and bend specimens,
ir
tests of the heat-affected zone and of
the weld metal, wide-plate tension
tests,
Much of this information is ob
tained by those steel companies that
have taken the lead in the US A in the
development of weldable s tructural
and press ure vessel steels. S hop and
field welding experience supplement
steel producer to suggest welding
practices, as illustrated by excerpts
(Fig . 1 and 2) from U. S . S teel
p u bl ic at io n s on U S S C O R - T E N B
s tee l and US S T -1 cons t ruct iona l
alloy steels. T he info rma tion is used
by specification-writing groups, such
as A S T M , A S M E , A W S , a nd
A A S HO , in cons ider ing approva l of
weldable s tructural and pressure ves
sel steels; this information is also used
by designers and fabricators to obtain
the maximum advantage from steel as
an engineering material .
development, acceptance, and sat is
factory use of a large family of welda
ble constructional steels, each with a
specific combination of strength, duc
tility, notch toughness, fatigue
strength, corrision resistance, and
cat ions and experience has not sug
gested a need. T he variety of weldable
constructional steels enables fabrica
welding experience and service per
fo rmance .
Summary
T he presen t paper p resen ts the US A
view on the question of whether and
to what extent the specification of
weldability should be incorporated in
ma terials specifications. R esults of
weldabil i ty research are summarized
to show that substantial progress has
been made in the development of
steels specifically for welded fabrica
t ion rather than depending on the
expanded use of steels customarily
joined by other methods .
with ductility, notch toughness, fatigue
strength, corrosion resistance, and
of weldable constructional steels is now
available to designers and fabricators.
T he steels range in yield point or yield
strength from 30 to 180 ksi (207 to
1 2 4 1 M N / m
2
wide range of plate thicknesses; some
are also available as structural shapes,
pipe,
multiplicity of weldable steels for
structural and pressure vessel applica
tions stems from the diversity of such
applicat ions, some being at customary
atmospheric temperatures, whereas
tempera tures .
in the US A in the development of the
weldable steels and have provided
sufficient information from welding
by specification-writing groups and
cations and experience has not sug
gested a need. T he variety of weldable
constructional steels enables fabrica
ability from experience.
N o 157
Significance of Fracture Extension Resistance (R Curve) Factors in Fracture-
Safe Design for Nonfrangible Metals,
by W. S. Pe llini and R. W. Judy, Jr.
R equirem ents for new direct ions in fracture research emerge from considerat ions of
the basic lack of applicability of K parameters for definition of the fracture extension
resistance of nonfrangible metals . New research is required into factors relat ing to the
increase in plastic wo rk energy resistance defined by R c urves. T he urg ency of such
studies evolves from the increasing use of metals of low-intensity plane stress (low-shelf
low-tearing-energy) characteris t ics in s tructures of high-compliance features . A case is
presented for the mutual consideration of metal-type structure-type relationships in
fracture-safe design. Present fracture-safe design practices do not include a rational ap
proac h to this quest ion. T he report provides an introduct ion to these considerat ions in
terms of extension of fracture mechanics concepts, as well as metallurgical factors and
engineering pract ices .
T he price of W R C B ullet in 157 is $1.50 per copy. Orders should be sent to the
Weld ing R esearch C ounc i l , 345 East 47 th S t . , New York , N .Y . 10017 .