Weld undercut on 304 stainless steel bar

[grayseal]

We have been experiencing undercut problems while fillet welding .625" diameter SA-479, type 304 stainless steel bar. We buy from several suppliers and it is only happens with bar from one of them. All bar is received with Certified Material Test Reports. What could be the cause of the undercut?

 

[GRoberts]

How do the sulfer levels compare on the bars? This affects the penetration, and amount of base metal melted, which in turn could affect undercut. Also, what process are you using?

 

[grayseal]

GRoberts,
Thanks for the reply. The sulfer contents on the material that undercuts is .026% for one heat and .027% for another. Other heats that weld fine contain .027% and .022%. We are using the TIG process. I have samples at the test lab now to verify the chemial analysis reported on the CMTR.
Thanks again,
grayseal