First, I am not a professional welder. Our company has been using 304L stainless steel for combustion chamber and heat exchanger assemblies using TIG welding and no filler material. We have been experiencing some cracks in the welds. We are considering switching to 309S or 310S which we understand would be better suited for this application. I have not been able to find information on the degree of difficulty in welding 309S or 310S versus 304L. I assume cracking of welds with 309S or 310S would be less of a problem. Any comments on the use or welding of these materials or a reference to go to will be greatly appreciated. I have read some of the responses to questions and have been impressed with the quality. Thanks.
Dear ChrisC
You weld 304L stainless steel without filler metal using TIG process. It means base metal is thin and you use flare-edge preparation. Do you do any preparation when your 304L stainless steel is plasma cut; grinding edges, for example?
About 80 percent of Atmosphere is Nitrogen. When you cut your stainless steel with air plasma, cut surfaces absorb nitrogen.
Nitrogen is a very powerful alloying element in stainless steel weld metal in terms of promoting austenite at the expense of ferrite (austenite and ferrite are two kind of metallurgical phase). It should be prevented to have full austenite weld metal because it prone to hot crack (a kind of cracks).
Best Regards
Chris, center line cracking is common when welding stainless autogenously when the preparation is not done properly (see the previous post). Switching to 309 or 310 for high temperature is correct. The addition of filler metal will help solve your problems. Is this an option?
Mike Sherman
Sherman Welding
By ChrisC
Date 01-11-2002 21:12
Thanks. I forgot to mention that the material is thin, 20 Ga.
I think using a filler is an option.
