Lincoln Electric Welder User Manual
STAINLESS STEELS
Properties – How To Weld Them – Where To Use Them
STAINLESS STEELS
TABLE OF
PROPERTIES –
HOW TO WELD THEM
WHERE TO USE THEM
A description of the physical and mechanical properties of a
variety of commercial stainless steels. Recommendations on the
applications of each type and how to arc weld each including
filler materials.
By
Damian Kotecki, PhD
Technical Director, Stainless and High Alloy
Product Development
and
Frank Armao
Senior Application Engineer
CONTENTS
1.0 Introduction ........................ 2
2.0 Types of Stainless Steels... 2
2.1 Ferrite Promoters
2.2 Austenite Promoters
2.3 Neutral Effect
3.0 Weldability of Stainless
Steels ....................................2
3.1 Ferritic Stainless Steels
3.2 Martensitic Stainless
Steels
3.3 Austenitic Stainless
Steels
3.3.1 Sensitization
3.3.2 Hot Cracking
3.4 Precipitation Hardening
Stainless Steels
3.5 Duplex Stainless Steels
4.0 Physical Properties .......... 10
5.0 Mechanical Properties ..... 10
6.0 Selection of a Stainless
Steel ....................................12
7.0 Design for Welding
Stainless Steels ..................14
8.0 Selection of Filler Metals ...14
9.0 Selection of a Welding
Process...............................18
9.1 Shielded Metal Arc
Welding
9.2 Submerged Arc Welding
9.3 Gas Metal Arc Welding
9.4 Flux Cored Arc Welding
9.5 Gas Tungsten Arc
Welding
10.0 Procedures for Welding
Stainless Steels ..................21
10.1 Welding with the Shielded
Metal Arc Process
10.2 Welding with the
Submerged Arc Process
10.3 Welding with the Gas
Metal Arc Process
10.4 Welding with the Gas
Tungsten Arc Process
Copyright © 2003
by The Lincoln Electric Company
All Rights Reserved
Sources of Additional
Information
Safety in Welding
WELDING OF STAINLESS STEELS
1.0
INTRODUCTION
Stainless steels are defined as iron
base alloys which contain at least
10.5% chromium. The thin but
dense chromium oxide film which
forms on the surface of a stainless
steel provides corrosion resistance
and prevents further oxidation. There
are five types of stainless steels
depending on the other alloying
additions present, and they range
from fully austenitic to fully ferritic.
2.0
TYPES OF
STAINLESS
STEELS
Austenitic stainless steels include
the 200 and 300 series of which
type 304 is the most common. The
primary alloying additions are
chromium and nickel. Ferritic
stainless steels are non-hardenable
Fe-Cr alloys. Types 405, 409, 430,
422 and 446 are representative of
this group. Martensitic stainless
steels are similar in composition to
the ferritic group but contain higher
carbon and lower chromium to
permit hardening by heat treatment.
Types 403, 410, 416 and 420 are
representative of this group. Duplex
stainless steels are supplied with a
microstructure of approximately equal
amounts of ferrite and austenite.
They contain roughly 24% chromium
and 5% nickel. Their numbering
system is not included in the 200,
300 or 400 groups. Precipitation
hardening stainless steels contain
alloying additions such as aluminum
which allow them to be hardened by
a solution and aging heat treatment.
They are further classified into sub
groups as martensitic, semiaustenitic
and austenitic precipitation hardening
stainless steels. They are identified
as the 600-series of stainless steels
(e.g., 630, 631, 660).
The alloying elements which appear
in stainless steels are classed as
ferrite promoters and austenite
promoters and are listed below.
2.1
FERRITE PROMOTERS
Chromium – provides basic
corrosion resistance.
Molybdenum – provides high
temperature strength and increases
corrosion resistance.
Niobium (Columbium), Titanium –
strong carbide formers.
2.2
AUSTENITE
PROMOTERS
Nickel – provides high temperature
strength and ductility.
Carbon – carbide former,
strengthener.
Nitrogen – increases strength,
reduces toughness.
2.3
NEUTRAL EFFECT
• Regarding Austenite & Ferrite
Manganese – sulfide former
Silicon – wetting agent
Sulfur and Selenium – improve
machinability, cause hot
cracking in welds.
3.0
WELDABILITY
OF STAINLESS
STEELS
Most stainless steels are considered
to have good weldability and may be
welded by several welding processes
including the arc welding processes,
resistance welding, electron and
laser beam welding, friction welding
and brazing. For any of these
processes, joint surfaces and any
filler metal must be clean.
The coefficient of thermal expansion
for the austenitic types is 50%
greater than that of carbon steel and
this must be considered to minimize
distortion. The low thermal and
electrical conductivity of austenitic
stainless steel is generally helpful in
welding. Less welding heat is
required to make a weld because the
heat is not conducted away from a
joint as rapidly as in carbon steel. In
resistance welding, lower current can
be used because resistivity is higher.
Stainless steels which require special
welding procedures are discussed in
later sections.
3.1
FERRITIC
STAINLESS STEELS
The ferritic stainless steels contain
10.5 to 30% Cr, up to 0.20% C and
sometimes ferrite promoters Al, Nb
(Cb), Ti and Mo. They are ferritic at
all temperatures, do not transform to
austenite and therefore, are not
hardenable by heat treatment. This
group includes the more common
types 405, 409, 430, 442 and 446.
Table I lists the nominal composition
2
TABLE I — Nominal Compositions of Ferritic Stainless Steels
Type Number C Mn Si Cr Ni PS Other
UNS
405 S40500 0.08 1.00 1.00 11.5-14.5 0.04 0.03 0.10-0.30 Al
409 S40900 0.08 1.00 1.00 10.5-11.75 0.045 0.045 6 x %C min. TI
429 S42900 0.12 1.00 1.00 14.0-16.0 0.04 0.03
430 S43000 0.12 1.00 1.00 16.0-18.0 0.04 0.03
430F** S43020 0.12 1.25 1.00 16.0-18.0 0.06 0.15 min. 0.06 Mo
430FSe** S43023 0.12 1.25 1.00 16.0-18.0 0.06 0.06 0.15 min. Se
430Ti S43036 0.10 1.00 1.00 16.0-19.5 0.75 0.04 0.03 5 x %C - Ti min.
434 S43400 0.12 1.00 1.00 16.0-18.0 0.04 0.03 0.75-1.25 Mo
436 S43600 0.12 1.00 1.00 16.0-18.0 0.04 0.03 0.75-1.25 Mo;
442 S44200 0.20 1.00 1.00 18.0-23.0 0.04 0.03
444 S44400 0.025 1.00 1.00 17.5-19.5 1.00 0.04 0.03 1.75-2.5 Mo, 0.035 N
446 S44600 0.20 1.50 1.00 23.0-27.0 0.04 0.03 0.25 N
18-2FM** S18200 0.08 2.50 1.00 17.5-19.5 0.04 0.15 min.
18SR 0.04 0.3 1.00 18.0 2.0 Al; 0.4 Ti
26-1 S44625 0.01 0.40 0.40 25.0-27.5 0.50 0.02 0.02 0.75-1.5 Mo; 0.015N;
(E-Brite) 0.2 Cu; 0.5 (Ni+Cu)
26-1Ti S44626 0.06 0.75 0.75 25.0-27.0 0.5 0.04 0.02 0.75-1.5 Mo; 0.04 N;
29-4 S44700 0.01 0.30 0.20 28.0-30.0 0.15 0.025 0.02 3.5-4.2 Mo
29-4-2 S44800 0.01 0.30 0.20 28.0-30.0 2.0-2.5 0.025 0.02 3.5-4.2 Mo
Monit S44635 0.25 1.00 0.75 24.5-26.0 3.5-4.5 0.04 0.03 3.5-4.5 Mo;
Sea-cure/ S44660 0.025 1.00 0.75 25.0-27.0 1.5-3.5 0.04 0.03 2.5-3.5 Mo;
Sc-1 0.2 + 4 (%C + %N)
Composition - Percent *
5 x %C min.
Nb(Cb) + Ta
0.2 + 4 (%C + %N);
(Ti +Nb(Cb) )
0.2 Cu; 0.2-1.0 Ti
0.3-0.6 (Ti + Nb(Cb) )
(Ti + Nb(Cb) )
*Single values are maximum values. (From ASM Metals Handbook, Ninth Edition, Volume 3)
of a number of standard and several
non-standard ferritic stainless steels.
They are characterized by weld and
HAZ grain growth which can result in
low toughness of welds.
To weld the ferritic stainless steels,
filler metals should be used which
match or exceed the Cr level of the
base alloy. Type 409 is available as
metal cored wire and Type 430 is
available in all forms. Austenitic
Types 309 and 312 may be used for
dissimilar joints. To minimize grain
growth, weld heat input should be
minimized, Preheat should be limited
to 300-450°F and used only for the
higher carbon ferritic stainless steels
(e.g., 430, 434, 442 and 446). Many
of the highly alloyed ferritic stainless
steels are only available in sheet and
**These grades are generally
considered to be unweldable.
3.2
MARTENSITIC
STAINLESS STEELS
The martensitic stainless steels
contain 11 to 18% Cr, up to 1.20% C
and small amounts of Mn and Ni
and, sometimes, Mo. These steels
will transform to austenite on heating
and, therefore, can be hardened by
formation of martensite on cooling.
This group includes Types 403, 410,
414, 416, 420, 422, 431 and 440.
Both standard and non-standard
martensitic stainless steels are listed
in Table II. They have a tendency
toward weld cracking on cooling
when hard brittle martensite is
formed.
Chromium and carbon content of the
filler metal should generally match
these elements in the base metal.
Type 410 filler is available as covered
electrode, solid wire and cored wire
and can be used to weld types 402,
410, 414 and 420 steels. Type
410NiMo filler metal can also be
used. When it is necessary to match
the carbon in Type 420 steel, Type
420 filler, which is available as solid
wire and cored wire, should be used.
Types 308, 309 and 310 austenitic
filler metals can be used to weld the
martensitic steels to themselves or to
other steels where good asdeposited toughness is required.
Preheating and interpass temperature
in the 400 to 600°F (204 to 316°C)
range is recommended for most
tube forms and are usually welded
by GTA without filler metal.
3
TABLE II — Nominal Compositions of Martensitic Stainless Steels
UNS Composition - Percent *
Type Number C Mn Si Cr Ni PS Other
403 S40300 0.15 1.00 0.50 11.5-13.0 0.04 0.03
410 S41000 0.15 1.00 1.00 11.5-13.0 0.04 0.03
410Cb S41040 0.18 1.00 1.00 11.5-13.5 0.04 0.03 0.05-0.3 Nb(Cb)
410S S41008 0.08 1.00 1.00 11.5-13.5 0.6 0.04 0.03
414 S41400 0.15 1.00 1.00 11.5-13.5 1.25-2.50 0.04 0.03
414L 0.06 0.50 0.15 12.5-13.0 2.5-3.0 0.04 0.03 0.5 Mo; 0.03 Al
416 S41600 0.15 1.25 1.00 12.0-14.0 0.04 0.03 0.6 Mo
416Se** S41623 0.15 1.25 1.00 12.0-14.0 0.06 0.06 0.15 min. Se
416 Plus X** S41610 0.15 1.5-2.5 1.00 12.0-14.0 0.06 0.15 min. 0.6 Mo
420 S42000 0.15 min. 1.00 1.00 12.0-14.0 0.04 0.03
420F** S42020 0.15 min. 1.25 1.00 12.0-14.0 0.06 0.15 min. 0.6 Mo
422 S42200 0.20-0.25 1.00 0.75 11.0-13.0 0.5-1.0 0.025 0.025 0.75-1.25 Mo;
0.75-1.25 W;
0.15-0.3 V
431 S43100 0.20 1.00 1.00 15.0-17.0 1.25-2.50 0.04 0.03
440A S44002 0.60-0.75 1.00 1.00 16.0-18.0 0.04 0.03 0.75 Mo
440B S44003 0.75-0.95 1.00 1.00 16.0-18.0 0.04 0.03 0.75 Mo
440C S44004 0.95-1.20 1.00 1.00 16.0-18.0 0.04 0.03 0.75 Mo
*Single values are maximum values. (From ASM Metals Handbook, Ninth Edition, Volume 3)
martensitic stainless steels. Steels
with over 0.20% C often require a
post weld heat treatment to soften
and toughen the weld.
3.3
AUSTENITIC
STAINLESS STEEL
The austenitic stainless steels contain
16-26% Cr, 8-24% Ni + Mn, up to
0.40% C and small amounts of a few
other elements such as Mo, Ti, Nb
(Cb) and Ta. The balance between
the Cr and Ni + Mn is normally
adjusted to provide a microstructure
of 90-100% austenite. These alloys
are characterized by good strength
and high toughness over a wide
temperature range and oxidation
resistance to over 1000°F (538°C).
This group includes Types 302, 304,
310, 316, 321 and 347. Nominal
composition of these and other
austenitic stainless steels are listed in
Table III. Filler metals for these
alloys should generally match the
base metal but for most alloys,
provide a microstructure with some
ferrite to avoid hot cracking as will be
**These grades are generally
considered to be unweldable.
discussed further. To achieve this,
Type 308 is used for Type 302 and
304 and Type 347 for Type 321. The
others should be welded with
matching filler. Type 347 can also be
welded with Type 308H filler. These
filler materials are available as coated
electrodes, solid bare wire and cored
wire. Type 321 is available on a
limited basis as solid and cored wire.
Two problems are associated with
welds in the austenitic stainless
steels: 1) sensitization of the weld
heat affected zone, and 2) hot
cracking of weld metal.
3.3.1 SENSITIZATION:
Sensitization leads to intergranular
corrosion in the heat affected zone as
shown in Figure 1. Sensitization is
caused by chromium carbide
formation and precipitation at grain
boundaries in the heat affected zone
when heated in the 800 to 1600°F
(427 to 871°C) temperature range.
Since most carbon is found near
grain boundaries, chromium carbide
formation removes some chromium
from solution near the grain
boundaries, thereby reducing the
corrosion resistance of these local
areas. This problem can be
remedied by using low carbon base
material and filler material to reduce
the amount of carbon available to
combine with chromium. Welds
should be made without preheat and
with minimum heat input to shorten
the time in the sensitization
temperature range.
The degree of carbide precipitation
increases with:
1. Higher carbon content (for
example, because 301 and 302
grades have a maximum carbon
content of 0.15% they are more
susceptible to carbon precipitation
than grade 304 which has a
maximum carbon content of only
0.08%).
2. Time at the critical mid-range
temperatures – a few seconds at
1200°F (649°C) can do more
damage than several minutes at
850°F (454°C) or 1450°F (788°C).
Welding naturally produces a
temperature gradient in the steel. It
ranges from melting temperature at
the weld to room temperature some
4
distance from the weld. A narrow
zone on each side of the weld
remains in the sensitizing
temperature range for sufficient time
for precipitation to occur. If used in
severely corrosive conditions, lines of
damaging corrosion appear
alongside each weld.
Control of Carbide Precipitation
The amount of carbide precipitation
is reduced by promoting rapid
cooling. Fortunately, the copper chill
bars, skip welding and other
techniques needed to control
distortion in sheet metal (see pg 34)
help reduce carbide precipitation.
Annealing the weldment at 1900°F
(1038°C) or higher, followed by water
quench, eliminates carbide
precipitation, but this is an expensive
and often impractical procedure.
Therefore, when weldments operate
in severe corrosive applications or
within the sensitizing temperature
range, either ELC or stablilized
grades are needed.
Another remedy is to use stabilized
stainless steel base metal and filler
materials which contain elements
that will react with carbon, leaving all
the chromium in solution to provide
corrosion resistance. Type 321 contains titanium and Type 347 contains
niobium (columbium) and tantalum,
all of which are stronger carbide
formers than chromium.
ELC – Extra Low Carbon –
Grades (304L, 308L)
The 0.04% maximum carbon
content of ELC grades helps
eliminate damaging carbide
precipitation caused by welding.
These grades are most often used
for weldments which operate in
severe corrosive conditions at
temperatures under 800°F (427°C).
ELC steels are generally welded with
the ELC electrode, AWS E308L-XX.
Although the stabilized electrodes
AWS E347-XX produce welds of
equal resistance to carbide
precipitation and similar mechanical
properties, the ELC electrode welds
tend to be less crack sensitive on
heavy sections and have better low
temperature notch toughness.
The low carbon content in ELC
grades leaves more chromium to
provide resistance to intergranular
corrosion.
Stabilized Grades (321, 347, 348)
Stabilized grades contain small
amounts of titanium (321), niobium
(columbium) (347), or a combination
of niobium and tantalum (347, 348).
These elements have a stronger
affinity for carbon then does
chromium, so they combine with the
carbon leaving the chromium to
provide corrosion resistance.
These grades are most often used in
severe corrosive conditions when
service temperatures reach the
sensitizing range. They are welded
with the niobium stabilized
electrodes, AWS E347-XX.
Type 321 electrodes are not
generally made because titanium is
lost in the arc. AWS E347-XX is
usually quite satisfactory for joining
type 321 base metal.
Molybdenum Grades
(316, 316L, 317, 317L, D319)
Molybdenum in stainless steel
increases the localized corrosion
resistance to many chemicals. These
steels are particularly effective in
combatting pitting corrosion. Their
most frequent use is in industrial
FIGURE 1
5
TABLE III — Nominal Compositions of Austenitic Stainless Steels
UNS Composition - Percent *
Type Number C Mn Si Cr Ni PS Other
201 S20100 0.15 5.5-7.5 1.00 16.0-18.0 3.5-5.5 0.06 0.03 0.25 N
202 S20200 0.15 7.5-10.0 1.00 17.0-19.0 4.0-6.0 0.06 0.03 0.25 N
205 S20500 0.12-0.25 14.0-15.5 1.00 16.5-18.0 1.0-1.75 0.06 0.03 0.32-0.40 N
216 S21600 0.08 7.5-9.0 1.00 17.5-22.0 5.0-7.0 0.045 0.03 2.0-3.0 Mo; 0.25-0.5 N
301 S30100 0.15 2.00 1.00 16.0-18.0 6.0-8.0 0.045 0.03
302 S30200 0.15 2.00 1.00 17.0-19.0 8.0-10.0 0.045 0.03
302B S30215 0.15 2.00 2.0-3.0 17.0-19.0 8.0-10.0 0.045 0.03
303** S30300 0.15 2.00 1.00 17.0-19.0 8.0-10.0 0.20 0.15 min. 0.6 Mo
303Se** S30323 0.15 2.00 1.00 17.0-19.0 8.0-10.0 0.20 0.06 0.15 min. Se
304 S30400 0.08 2.00 1.00 18.0-20.0 8.0-10.5 0.045 0.03
304H S30409 0.04-0.10 2.00 1.00 18.0-20.0 8.0-10.5 0.045 0.03
304L S30403 0.03 2.00 1.00 18.0-20.0 8.0-12.0 0.045 0.03
304LN S30453 0.03 2.00 1.00 18.0-20.0 8.0-10.5 0.045 0.03 0.10-0.15 N
S30430 S30430 0.08 2.00 1.00 17.0-19.0 8.0-10.0 0.045 0.03 3.0-4.0 Cu
304N S30451 0.08 2.00 1.00 18.0-20.0 8.0-10.5 0.045 0.03 0.10-0.16 N
304HN S30452 0.04-0.10 2.00 1.00 18.0-20.0 8.0-10.5 0.045 0.03 0.10-0.16 N
305 S30500 0.12 2.00 1.00 17.0-19.0 10.5-13.0 0.045 0.03
308 S30800 0.08 2.00 1.00 19.0-21.0 10.0-12.0 0.045 0.03
308L 0.03 2.00 1.00 19.0-21.0 10.0-12.0 0.045 0.03
309 S30900 0.20 2.00 1.00 22.0-24.0 12.0-15.0 0.045 0.03
309S S30908 0.08 2.00 1.00 22.0-24.0 12.0-15.0 0.045 0.03
309S Cb S30940 0.08 2.00 1.00 22.0-24.0 12.0-15.0 0.045 0.03 8 x %C - Nb(Cb)
309 Cb + Ta 0.08 2.00 1.00 22.0-24.0 12.0-15.0 0.045 0.03 8 x %C (Nb(Cb) + Ta)
310 S31000 0.25 2.00 1.50 24.0-26.0 19.0-22.0 0.045 0.03
310S S31008 0.08 2.00 1.50 24.0-26.0 19.0-22.0 0.045 0.03
312 0.15 2.00 1.00 30.0 nom. 9.0 nom. 0.045 0.03
254SMo S31254 0.020 1.00 0.80 19.5-20.5 17.50-18.5 0.03 0.010 6.00-6.50Mo; 0.18-0.22N;
Cu=0.5-1.00
314 S31400 0.25 2.00 1.5-3.0 23.0-26.0 19.0-22.0 0.045 0.03
316 S31600 0.08 2.00 1.00 16.0-18.0 10.0-14.0 0.045 0.03 2.0-3.0 Mo
316F** S31620 0.08 2.00 1.00 16.0-18.0 10.0-14.0 0.20 0.10 min. 1.75-2.5 Mo
316H S31609 0.04-0.10 2.00 1.00 16.0-18.0 10.0-14.0 0.045 0.03 2.0-3.0 Mo
316L S31603 0.03 2.00 1.00 16.0-18.0 10.0-14.0 0.045 0.03 2.0-3.0 Mo
316LN S31653 0.03 2.00 1.00 16.0-18.0 10.0-14.0 0.045 0.03 2.0-3.0 Mo; 0.10-0.30 N
316N S31651 0.08 2.00 1.00 16.0-18.0 10.0-14.0 0.045 0.03 2.0-3.0 Mo; 0.10-0.16 N
317 S31700 0.08 2.00 1.00 18.0-20.0 11.0-15.0 0.045 0.03 3.0-4.0 Mo
317L S31703 0.03 2.00 1.00 18.0-20.0 11.0-15.0 0.045 0.03 3.0-4.0 Mo
317M S31725 0.03 2.00 1.00 18.0-20.0 12.0-16.0 0.045 0.03 4.0-5.0 Mo
321 S32100 0.08 2.00 1.00 17.0-19.0 9.0-12.0 0.045 0.03 5 x %C min. Ti
321H S32109 0.04-0.10 2.00 1.00 17.0-19.0 9.0-12.0 0.045 0.03 5 x %C min. Ti
329 S32900 0.10 2.00 1.00 25.0-30.0 3.0-6.0 0.045 0.03 1.0-2.0 Mo
330 N08330 0.08 2.00 0.75-1.5 17.0-20.0 34.0-37.0 0.04 0.03
AL6-XN N80367 0.030 2.00 1.00 20.0-22.0 23.5-25.5 0.04 0.03 6.00-7.00Mo; 0.18-0.25N;
Cu=0.75
330HC 0.40 1.50 1.25 19.0 nom. 35.0 nom.
332 0.04 1.00 0.50 21.5 nom. 32.0 nom. 0.045 0.03
347 S34700 0.08 2.00 1.00 17.0-19.0 9.0-13.0 0.045 0.03 10 x %C min. Nb(Cb) +Ta
347H S34709 0.04-0.10 2.00 1.00 17.0-19.0 9.0-13.0 0.045 0.03 10 x %C min. Nb(Cb) + Ta
348 S34800 0.08 2.00 1.00 17.0-19.0 9.0-13.0 0.045 0.03 0.2 Cu; 10 x %C min. Nb(Cb) + Ta(c)
348H S34809 0.04-0.10 2.00 1.00 17.0-19.0 9.0-13.0 0.045 0.03 0.2 Cu; 10 x %C min. Nb(Cb) + Ta
384 S38400 0.08 2.00 1.00 15.0-17.0 17.0-19.0 0.045 0.03
Nitronic 32 S24100 0.10 12.0 0.50 18.0 1.6 0.35 N
Nitronic 33 S24000 0.06 13.0 0.5 18.0 3.0 0.30 N
Nitronic 40 S21900 0.08 8.0-10.0 1.00 18.0-20.0 5.0-7.0 0.06 0.03 0.15-0.40 N
Nitronic 50 S20910 0.06 4.0-6.0 1.00 20.5-23.5 11.5-13.5 0.04 0.03 1.5-3.0 Mo; 0.2-0.4 N;
0.1-0.3 Cb; 0.1-0.3 V
Nitronic 60 S21800 0.10 7.0-9.0 3.5-4.5 16.0-18.0 8.0-9.0 0.04 0.03 1.5-3.0 Mo; 0.2-0.4 N;
6
*Single values are maximum values. (From ASM Metals Handbook, Ninth Edition, Volume 3)
**These grades are generally
considered to be unweldable.
processing equipment. 316 and
316L are welded with AWS E316LXX electrodes.
316L and 317L are ELC grades that
must be welded with ELC type
electrodes to maintain resistance to
carbide precipitation. 317 and 317L
are generally welded with E317 or
E317L electrodes respectively. They
can be welded with AWS E316-XX
electrode, but the welds are slightly
lower in molybdenum content than
the base metal with a corresponding
lower corrosion resistance.
When hot oxidizing acids are
encountered in service, E316,
E316L, E317 or E317L welds may
have poor corrosion resistance in the
as-welded condition. In such cases,
E309 or E309Cb electrodes may be
better. As an alternative, the following
heat treatment will restore corrosion
resistance to the weld:
1. For 316 or 317 – full anneal at
1950-2050°F (1066-1121°C).
2. For 316L and 317L – stress relieve
at 1600°F (871°C).
High Temperature Grades
(302B, 304H, 309,
309S, 310, 310S)
E310-XX welds on heavy plate tend
to be more crack sensitive than
E309-XX weld metals.
Free Machining Grades
(303, 303Se)
Production welding of these grades
is not recommended because the
sulfur or selenium and phosphorus
cause severe porosity and hot short
cracking.
If welding is necessary, special E312XX or E309-XX electrodes are
recommended because their high
ferrite reduces cracking tendencies.
Use techniques that reduce
admixture of base metal into the
weld metal and produce convex
bead shapes.
3.3.2 HOT CRACKING:
Hot cracking is caused by low
melting materials such as metallic
compounds of sulfur and
phosphorous which tend to penetrate
grain boundaries. When these
compounds are present in the weld
or heat affected zone, they will
penetrate grain boundaries and
cracks will appear as the weld cools
and shrinkage stresses develop.
Hot cracking can be prevented by
adjusting the composition of the
base material and filler material to
obtain a microstructure with a small
amount of ferrite in the austenite
matrix. The ferrite provides ferriteaustenite grain boundaries which are
able to control the sulfur and
phosphorous compounds so they do
not permit hot cracking. This
problem could be avoided by
reducing the S and P to very low
amounts, but this would increase
significantly the cost of making the
steel.
Normally a ferrite level of 4 FN
minimum is recommended to avoid
hot cracking. Ferrite is best
determined by measurement with a
magnetic instrument calibrated to
AWS A4.2 or ISO 8249. It can also
be estimated from the composition of
the base material and filler material
with the use of any of several constitution diagrams. The oldest of these
is the 1948 Schaeffler Diagram. The
Cr equivalent (% Cr + % Mo + 1.5 x
% Si + 0.5 x % Cb) is plotted on
These high alloy grades
maintain strength at high
temperatures and have
good scaling resistance.
They are primarily used
in industrial equipment at
high service
temperatures –
sometimes over 2000°F
(1093°C).
AWS E310-XX
electrodes are needed to
match the high
temperature properties
and scaling resistance of
grades 310 and 310S.
302B and 309 grades
are generally welded
with E309-XX
electrodes. 304H is
generally welded with
E308H-XX electrodes.
E310-XX electrodes can
be used on light plate.
= Ni + 35C + 20N + 0.25Cu
eq
Ni
Creq= Cr + Mo + 0.7Cb
FIGURE 2 — New 1992 WRC diagram including solidification mode boundaries.
(Updated from T.A. Siewert, C.N. McCowan and D.L. Olson – Welding Journal,
December 1988 by D.J. Kotecki and T.A. Siewert - Welding Journal, May 1992.)
7
TABLE IV — Nominal Compositions of Precipitation Hardening and Duplex Stainless Steels
UNS Composition - Percent *
Type Number C Mn Si Cr Ni PS Other
Precipitation-Hardening Types
PH 13-8 Mo S13800 0.05 0.10 0.10 12.25-13.25 7.5-8.5 0.01 0.008 2.0-2.5 Mo;
15-5 PH S15500 0.07 1.00 1.00 14.0-15.5 3.5-5.5 0.04 0.03 2.5-4.5 Cu;
17-4 PH S17400 0.07 1.00 1.00 15.5-17.5 3.0-5.0 0.04 0.03 630 3.0-5.0 Cu;
17-7 PH S17700 0.09 1.00 1.00 16.0-18.0 6.5-7.75 0.04 0.03 631 0.75-1.15 Al
PH 15-7 Mo S15700 0.09 1.00 1.00 14.0-16.0 6.5-7.75 0.04 0.03 2.0-3.0 Mo; 0.75-1.5 Al
17-10 P 0.07 0.75 0.50 17.0 10.5 0.28
A286 S66286 0.08 2.00 1.00 13.5-16.0 24.0-27.0 0.040 0.030 660 1.0-1.5 Mo; 2 Ti; 0.3 V
AM350 S35000 0.07-0.11 0.5-1.25 0.50 16.0-17.0 4.0-5.0 0.04 0.03 2.5-3.25 Mo; 0.07-0.13 N
AM355 S35500 0.10-0.15 0.5-1.25 0.50 15.0-16.0 4.0-5.0 0.04 0.03 2.5-3.25 Mo
AM363 0.04 0.15 0.05 11.0 4.0 0.25 Ti
Custom 450 S45000 0.05 1.00 1.00 14.0-16.0 5.0-7.0 0.03 0.03 1.25-1.75 Cu; 0.5-1.0 Mo
Custom 455 S45500 0.05 0.50 0.50 11.0-12.5 7.5-9.5 0.04 0.03 0.5 Mo; 1.5-2.5 Cu;
Stainless W S17600 0.08 1.00 1.00 16.0-17.5 6.0-7.5 0.04 0.03 0.4 Al; 0.4-1.2 Ti
Duplex Types
2205 S32205 0.03 2.0 1.0 22.0 5.5 0.03 0.02 3.0 Mo; 0.18 N
2304 S32304 0.03 2.5 1.0 23.0 4.0 0.1 N
255 0.04 1.5 1.0 25.5 5.5 3.0 Mo; 0.17 N; 2.0 Cu
NU744LN 0.067 1.7 0.44 21.6 4.9 2.4 Mo; 0.10 N; 0.2 Cu
2507 S32750 0.03 1.2 0.8 25 5.5 0.035 0.020 4 Mo; 0.28 N
*Single values are maximum values. (From ASM Metals Handbook, Ninth Edition, Volume 3) and ASTM A638
ASTM
A
GRADE
0.90-1.35 Al; 0.01 N
8 x %C -
Nb(Cb)
Nb(Cb)
Nb(Cb)
0.15-0.45
0.15-0.45
0.8-1.4 Ti; 0.1-0.5
+ Ta
+ Ta
Nb(Cb)
the horizontal axis and the nickel
equivalent (% Ni + 30 x % C + 0.5 x
% Mn) on the vertical axis. Despite
long use, the Schaeffler Diagram is
now outdated because it does not
consider nitrogen effects and
because it has not proven possible to
establish agreement among several
measurers as to the ferrite percent in
a given weld metal.
An improvement on the Schaeffler
Diagram is the 1973 WRC-DeLong
Diagram, which can be used to
estimate ferrite level. The main
differences are that the DeLong
Diagram includes nitrogen (N) in the
Ni equivalent (% Ni + 30 x % C x 30
x % N + 0.5 x % Mn) and shows
Ferrite Numbers in addition to
“percent ferrite.” Ferrite Numbers at
low levels may approximate “percent
ferrite.” The most recent diagram,
the WRC-1992 Diagram, Figure 2, is
considered to be the most accurate
predicting diagram at present. The
WRC-1992 Diagram has replaced the
WRC-DeLong Diagram in the ASME
Code with publication of the 1994-95
Winter Addendum. Its Ni equivalent
8
(% Ni + 35 x % C + 20 x % N + 0.25
Cu) and Cr equivalent (% Cr + % Mo
+ 0.7 x % Cb) differ from those of
Schaeffler and WRC-DeLong.
Ferrite Number may be estimated by
drawing a horizontal line across the
diagram from the nickel equivalent
number and a vertical line from the
chromium equivalent number. The
Ferrite Number is indicated by the
diagonal line which passes through
the intersection of the horizontal and
vertical lines.
Predictions by the WRC-1992 and
WRC-DeLong Diagrams for common
grades like 308 are similar, but the
WRC-1992 diagram generally is more
accurate for higher alloy and less
common grades like high manganese
austenitic or duplex ferritic-austenitic
stainless steels.
Ferrite Number can be measured
directly on weld deposits from the
magnetic properties of the ferrite.
Several instruments are available
commercially, including the Magne
Gage, the Severn Gage, the
Inspector Gage and the Ferritescope
which can be calibrated to AWS A4.2
or ISO 8249 and provide readings in
Ferrite Number.
The amount of ferrite normally should
not be greater than necessary to
prevent hot cracking with some
margin of safety. The presence of
ferrite can reduce corrosion
resistance in certain media and
excess ferrite can impair ductility and
toughness.
3.4
PRECIPITATION
HARDENING
STAINLESS STEELS
There are three categories of precipitation hardening stainless steels –
martensitic, semiaustenitic and
austenitic.
The martensitic stainless steels can
be hardened by quenching from the
austenitizing temperature [around
1900°F (1038°C)] then aging
between 900 to 1150°F (482 to
621°C). Since these steels contain
less than 0.07% carbon, the martensite is not very hard and the main
hardening is obtained from the aging
(precipitation) reaction. Examples of
this group are 17-4PH, 15-5PH and
PH13-8Mo. Nominal compositions
of precipitation hardening stainless
steels are listed in Table IV.
The semiaustenitic stainless steels
will not transform to martensite when
cooled from the austenitizing temperature because the martensite
transformation temperature is below
room temperature. These steels
must be given a conditioning
treatment which consists of heating
in the range of 1350 to 1750°F (732
to 954°C) to precipitate carbon
and/or alloy elements as carbides or
intermetallic compounds. This
removes alloy elements from solution,
thereby destabilizing the austenite,
which raises the martensite
transformation temperature so that a
martensite structure will be obtained
on cooling to room temperature.
Aging the steel between 850 and
1100°F (454 to 593°C) will stress
relieve and temper the martensite to
increase toughness, ductility, hardness and corrosion resistance.
Examples of this group are 17-7PH,
PH 15-7 Mo and AM 350.
The austenitic precipitation hardening
stainless steels remain austenitic after
quenching from the solutioning
temperature even after substantial
amounts of cold work. They are
hardened only by the aging reaction.
This would include solution treating
between 1800 and 2050°F (982 to
1121°C), oil or water quenching and
aging at 1300 to 1350°F (704 to
732°C) for up to 24 hours.
Examples of these steels include
A286 and 17-10P.
If maximum strength is required in
martensitic and semiaustenitic precipitation hardening stainless steels,
matching or nearly matching filler
metal should be used and the component, before welding, should be in
the annealed or solution annealed
condition. Often, Type 630 filler
metal, which is nearly identical with
17-4PH base metal, is used for
martensitic and semiaustenitic PH
stainlesses. After welding, a
complete solution heat treatment
plus an aging treatment is preferred.
If the post weld solution treatment is
not feasible, the components should
be solution treated before welding
then aged after welding. Thick
sections of highly restrained parts
are sometimes welded in the
overaged condition. These would
require a full heat treatment after
welding to attain maximum strength.
The austenitic precipitation hardening
stainless steels are the most difficult
to weld because of hot cracking.
Welding should preferably be done
with the parts in the solution treated
condition, under minimum restraint
and with minimum heat input. Nickel
base alloy filler metals of the NiCrFe
type or conventional austenitic stainless steel type are often preferred.
3.5
DUPLEX
STAINLESS STEELS
Duplex Ferritic – Austenitic
Stainless Steels
Duplex stainless steels solidify as
100% ferrite, but about half of the
ferrite transforms to austenite during
cooling through temperatures above
approx. 1900°F (1040°C). This
behavior is accomplished by
increasing Cr and decreasing Ni as
compared to austenitic grades.
Nitrogen is deliberately added to
speed up the rate of austenite
formation during cooling. Duplex
stainless steels are ferromagnetic.
They combine higher strength than
austenitic stainless steels with
fabrication properties similar to
austenitics, and with resistance to
chloride stress corrosion cracking of
ferritic stainless steels. The most
common grade is 2205 (UNS
S32205), consisting of 22%Cr, 5%Ni,
3%Mo and 0.15%N.
TABLE V — Physical Properties of Groups of Stainless Steels
Austenitic Ferritic Martensitic Precipitation
Property Types Types Types Hardening Types
6
Elastic Modulus; 10
Density; lb./in.
Coeff. of Therm. Expansion: µin./in. °F 9.2 5.8 5.7 6.0
Thermal. Conduct.; Btu/hrft. °F 9.1 14.5 14.0 12.9
Specific Heat; Btu/lb. °F 0.12 0.11 0.11 0.11
Electrical Resistivity, µΩcm 74 61 61 80
Magnetic Permeability 1.02 600-1,100 700-1000 95
Melting Range °F 2,500-2,650 2,600-2,790 2,600-2,790 2,560-2,625
psi 28.3 29.0 29.0 29.0
GPa 195 200 200 200
3
3
g/cm
µm/m °C 16.6 10.4 10.3 10.8
w/mk 15.7 25.1 24.2 22.3
J/k °K 500 460 460 460
°C 1,375-1,450 1,425-1,530 1,425-1,530 1,400-1,440
0.29 0.28 0.28 0.28
8.0 7.8 7.8 7.8
9
TABLE VI — Properties of Austenitic Stainless Steels
Tensile Strength 0.2% Yield Strength Elong. R.A. Hardness
Type Condition Ksi MPa Ksi MPa %%Rockwell
201 Anneal 115 793 55 379 55 B90
201 Full Hard 185 1275 140 965 4 C41
202 Anneal 105 724 55 379 55 B90
301 Anneal 110 758 40 276 60 B85
301 Full Hard 185 1275 140 965 8 C41
302 Anneal 90 620 37 255 55 65 B82
302B Anneal 95 655 40 276 50 65 B85
303 Anneal 90 620 35 241 50 55 B84
304 Anneal 85 586 35 241 55 65 B80
304L Anneal 80 552 30 207 55 65 B76
304N Anneal 85 586 35 241 30
304LN Anneal 80 552 30 207
305 Anneal 85 586 37 255 55 70 B82
308 Anneal 85 586 35 241 55 65 B80
308L Anneal 80 551 30 207 55 65 B76
309 Anneal 90 620 40 276 45 65 B85
310 Anneal 95 655 40 276 45 65 B87
312 Anneal 95 655 20
314 Anneal 100 689 50 345 45 60 B87
316 Anneal 85 586 35 241 55 70 B80
316L Anneal 78 538 30 207 55 65 B76
316F Anneal 85 586 35 241 55 70 B80
317 Anneal 90 620 40 276 50 55 B85
317L Anneal 85 586 35 241 50 55 B80
321 Anneal 87 599 35 241 55 65 B80
347/348 Anneal 92 634 35 241 50 65 B84
329 Anneal 105 724 80 552 25 50 B98
330 Anneal 80 550 35 241 30 B80
330HC Anneal 85 586 42 290 45 65
332 Anneal 80 552 35 241 45 70
384 Anneal 80 550
(From ASM Metals Handbook, 8th Edition, Volume 1; and 9th Edition, Volume 3 and ASTM standards)
4.0
PHYSICAL
stainless steel, it can be found in the
ASM Metals Handbook, Ninth
Edition, Volume 3.
PROPERTIES
Average physical properties for each
of the main groups of stainless steel
are listed in Table V. This includes
elastic modulus, density, coefficient
of thermal expansion, thermal conductivity, specific heat, electrical
resistivity, magnetic permeability and
melting range. These values should
be close enough for most engineering purposes. If more precise data is
required for a particular type of
10
5.0
MECHANICAL
PROPERTIES
Nominal mechanical properties of
austenitic and ferritic stainless steels
in the annealed condition are listed in
Table VI and Table VII respectively.
The austenitic stainless steels
generally have higher tensile
strengths and elongation than the
ferritic stainless steels but lower yield
strengths. Reduction in area is
about the same for both groups.
Nominal mechanical properties of
martensitic stainless steels in both
the annealed and tempered condition
are listed in Table VIII. The
tempered condition involves heating
to austenitize, cooling to form
martensite and reheating to the
indicated temperature to increase
toughness. Table IX lists the
mechanical properties of the precipitation hardening stainless steels as
solution annealed and after aging
treatments at the temperature
indicated. Properties of three duplex
stainless steels are included.
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