stainless 316 L

[grouse1]

I have a stainless 316L fitting that is friction welded w/ recent welds not passing pressure testing. No supllier change and no process change but noticed that shipment of new fitting (fitting that wont pass pressure test after weld)is slightly magnetic relative to old fittings. I suspect some degree of martensitic transformation in the new fittings vs old. Question: could the martensite impact weldability to any significant degree and should I be concerned about corrosion resistance.

Thanks

 

[metengr]

I would expect the slight magnetism is from ferrite in the 316L, not martensite. Are you joining the 316L fitting using friction welding to a dissimilar material?

 

[grouse1]

I agree with the ferrite vs. martensite comment. The weld is to a low carbon ( 0.03 ) steel plate.

thanks

 

[EdStainless]

The joint failures are related to an uncontrolled process. Either some geometry issue or process issue. The residual ferrite level in the SS will not impact this.
It could be that the process will not handle SS of different strength levels. There can be quite a range in strength for annealed SS.

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[strider6]

316L Stainless Steel will never develop martensite phase during welding process. In fact 316L can't be hardened by thermal process like the martensitic SS.
I suggest a metallurgical analysis of the welding to understand the reason of the failure and maybe a chemical analysis of the materials to be sure that it's a 316L SS.
Regarding the corrosion resistance, is would be necessary to know in which service and operating conditions the fitting will be used.

regards

Strider

http://www.corrosionist.com