effect of multiple weld repair at Stainless Steel 304L 1

[ahmadire]

[sup]Dear Experts,
As a concerning issue I want to know how many times are we allowed to perform weld repair at SS 304L(base metal) & 308L (Filler Metal)? My concern is about sensitization and probable outcome!
Thanks

 

[metengr]

I know of no limit for the number of repair attempts for 304L base material. As you stated, the concern is sensitization, which for a low (L) carbon grade is not as significant as a high carbon version of 304.I would simulate several repair attempts on a sample of material and evaluate the outcome.

 

[EdStainless]

I have seen failures in weld repairs because of surface contamination resulting in high C and/or S in later welds.
Why you are repairing matters. For example if it is because of thermal fatigue then you may never get a repair to last.

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P.E. Metallurgy, Plymouth Tube

 

[xianglecn]

no care the times, but the full heat treatment is necessary after welding repair, solution!!!
sometimes the repair will cause the carbon/Cr/Mo differnet, take care the node.

 

[weldstan]

Sensitization can and most likely will occur with multiple repairs in the same location. Whether or not this will be a problem in service will depend on the nature of the service.

 

[ahmadire]

[sup]Thank you all for your help...After forming we have faced new issue...the Brinell hardness of nearly entire surface has increased up to 290 HB ...and as you know the limit for 304L is 201 HB (not formed but as rolled)...What I want to know is that what is the reason of this change? Cold work or other situation? Whats the solution? S.A PWHT?[/sup]

 

[ahmadire]

What is the upper limit for Brinell hardness of formed head of stainless steel material??
are we allowed to have any hardness number after forming of SS?

 

[metengr]

The hardness of 290 HB implies cold worked material. The head should be solution annealed to remove the effects of cold worked material and have maximum corrosion resistance.

 

[EdStainless]

If you cold work welds they will get even harder than the base metal as residual delta ferrite transforms to martensite. Annealing is you only option.

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P.E. Metallurgy, Plymouth Tube

 

[ahmadire]

Dear metenger
could you please give the reference of 290 HB? It would be great assistance.

 

[ahmadire]

EdStainless The hardness of weld is lower than base metal (in common range) because of having coarse grain in comparison with base metal grains.

 

[remetaper]

Ed Stainless:in welded (fused ) austenitic structures, delta ferrite doesn't transform in martensite after cold working. Only austenite could have this behaviour. Probably, you are reffering to transformation of delta ferrite into sigma phase.

 

[metengr]

Please search and review the literaure on hardness values of solution annealed versus cold worked austenitic stainless steel.

 

[ahmadire]

metenger could you please give me a communication link or address for technical issues?