stainless cracks

[mikeb]

Today I stick welded a bulk feed screw transition. The job consisted of vertical welding 1/8" stainless sheet to painted galvanized 1/4" carbon steel angle flanges. I began using 308 rod, but the rate was so slow on the dirty metal that I switched to 6011 to finish quickly. The welds looked great, but as soon as the crane let the shaft go, all the 6011 welds split down the middle. Why?
I patched them all up with stainless rod, but it still upsets me.

Also, what are the best motions for out of position stick welding stainless?

[Mike Sherman]

The weld cracked because of the formation of martensite in the weld, giving you a hard, brittle weld. You need to have 8 to 9% ferrite in this particular weld to be resistant to cracks. Use E309 filler metal when welding 304 to carbon steel. Butter a pass onto the properly prepared carbon steel and then weld the two pieces together. Which brings us to the next point, you mentioned the material was dirty. This is a bad scenario for welding stainless. Clean the steel up just like you would for low hydrogen code work. By the way, keep your stainless electrodes in an oven, they are considered a low hydrogen electrode.

[mikeb]

thanks

Thanks Mike

Next time I'll burn the paint and zinc off with a torch. Some welders I work with make good joints without prep regardless of the conditions; how?

[Mike Sherman]

Experience will teach you how to make a good looking weld with crappy conditions, however, just because it looks good, doesn't make it good. I have always been more concerned with my work actually being good, I always take the time to clean material to the best of my ability. I have seven employees and I instruct them to take the time also. All metals will weld better when properly prepared. I often spend more time in preperation of welding than in actual weld time.

[mikeb]

You must be great to work for. My bosses tell me, "Weld like **** and get it done; dinner's waitin'!". It's all about time and materials.