elongation increase

Date 08-26-2011 19:03

There is not a whole lot you can do with weld parameters to improve elongation beyond what would be inherent in the chemistry. It will vary but only within a narrow band of scatter unless you fubar the thing and embrittle it, which is of course going the wrong way. 33% elongation is actually quite decent. 40% elongation in 316L weldments is an odd requirement.
You might be able to increase it by post weld annealing but I'm not sure how much.
SFA 5.22 has the min elongation at 30% in the as welded condition.
SA-240 plate has 40% min but thats in the annealed condition.
I'm still not sure the weld metal is gonna get there. But thats your best shot IMO.

By cddolan74 (**)

Date 08-26-2011 19:46

I agree, annealing would get me a higher elongation. Thinking this customer may be trying to cut a step out, but he gets to pay for this experiment. will post results with the new parameters. and thanks for the reply. I enjoy reading your responses.

By G.S.Crisi (****)

Date 08-26-2011 23:05 Edited 08-29-2011 19:35

Yes, annealing would increase elongation with no doubt, and 316 L should withstand annealing with no problems of carbide intergranular precipitation BUT, in my professional life I have already annealed a piece of equipment made of 304 L (was a dearator's dome) and after the annealing it was black due to carbide precipitation. This gave origin to endless discussions with our client.
So, I suggest you to be very careful.
First. Get sure your material IS 316 L.
Second. If possible, cut a little piece out of it and submit it to the annealing operation to see what happens.
Good luck.
Giovanni S. Crisi
Sao Paulo - Brazil

By cddolan74 (**)

Date 08-29-2011 15:15

I think I always misunderstood how carbide precipitation occurs in the L grade SS. Does the Cr C ratio elminate or just minimize carbide precipitation in the sensitization range??

By js55

Date 08-30-2011 13:52

In time you will always experience carbide precipitation. Having an L grade does not eliminate it. It only minimizes it to a degree that maintains corrosion properties. At high temp the carbon moves around looking for love.

By G.S.Crisi (****)

Date 08-30-2011 19:54

js55 has answered your question.
Thanks, js55
Giovanni S. Crisi

By defaced (**)

Date 08-29-2011 13:31

What test are you running to determine elongation? 40% in 2" like a tensile, or 40% outer fiber elongation from a bend, or...? And if you're doing a bend, what kind, side bend or wrap around?

By cddolan74 (**)

Date 08-29-2011 15:25

testing material to SFA-5.4 tesile speciman is .5" dia. our elongation results come from that testing. But you bring up a good point about the outer fiber elongation I'll have to look into that.