Page 13 - HIWT Spring 2011 World of Welding

hiwt@welding.org HOBART INSTITUTE OF WELDING TECHNOLOGY

FILLER METAL SELECTION FOR STAINLESS STEEL

By
Elmer Swank, Jr.
AWS-CWI/CWE
Technical Instructor If the base metal is a 304L (L = low carbon or .03% max.)
Hobart Institute of then the filler metal must also be low carbon, like 308L.
Welding Technology A 304 wire is not listed in the filler metal specification.
We can use the 308 filler wire to weld 308 and most of
the lower grades. Nearly all higher grades like 316 have
filler metals that are a perfect match.

If a filler metal manufacturer made a 304 wire, its use
would be limited to 304 base metal and thus, a limited
market would be served. Whereas, the 308 wire is used
QUESTION: on 308, 304, 302, 301, 205, 202, and 201 base metals.
More applications result in a broader market. Some of
I have a question regarding stainless steel filler rod the lower alloys are not widely used; so making a filler
metallurgy. Frequently the weld department of the wire for each one would be economically impractical.
company I work for receives blueprints from the The slight over-match in this case gives the weld better
engineering department that specify the use of “304 chemical characteristics than the base metal without any
filler rod” on weldments fabricated from 308 stainless. additional costs. What a great deal!
When told that 304 filler rod is nonexistent and that
most textbooks recommend 308 filler rod they seem
skeptical. Could you tell me the reason
that 304-alloy filler rod is not available,
and why 308 is the proper filler metal
for joining 304 stainless steel?

ANSWER:

The selection of filler metal for welding
the 300 series austenitic stainless steel
base metals is to match or slightly over-
match the chemical composition. The
304 stainless steel has 18% to 20%
chromium and 8% to 10.5% nickel.
The carbon content is .08% maximum.
The American Welding Society A5.9
Specification for Bare Stainless Steel
Welding Electrodes and Rods shows the
composition of 308 filler wire as 19.5%
to 22% chromium, 9% to 11% nickel,
with the same .08% carbon maximum.
Since the chromium and nickel content
of the filler wire is slightly higher than
that of the base metal, it is a good
choice.

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