Stellite 6 Hard Facing onto Monel

[mqas]

I am currently applying stellite 6 onto cast monel 400 (ASTM A494-M35-1) using PTA and normally use an Inconel 625 buttering layer. The prequlualified procedure has worked well in the past however, current production tests are showing intergranular cracking in the Monel / Inconel HAZ, but only after application of the Stellite.

Any comments much appreciated.

 

[metengr]

mqas;
What do you mean by a pre-qualified welding procedure? Was the original welding procedure qualified in accordance with ASME Section IX guidelines using bend and tensile testing or using a weld overlay qualification.

Are you sure the problem is after the deposition of Stellite 6? Did you confirm this by destructive examination?

If the procedure was properly qualified, go back and check to make sure that the production welding is following the essential variables of the actual qualified welding procedure. In some cases, the butter layer that is applied on the Monel may not be thick enough and dilution effects may be causing the problems.

 

[mqas]

Thank you Metengr,

The original WPS was qualified to ASME IX.

We machine the Inconel 625 and perform Dye Pen, prior to applying the Stellite.

I will double check on the welding parameters and butter layer thickness and revert.

Regards

 

[metengr]

mqas;
One other item to check on is to be sure that prior to welding the Stellite 6 the machined surface has to be absolutely clean of any cutting fluids.

 

[EdStainless]

Also double check the trace elements in the castings. A shift in chemistry could raise some issues,
But I am with Metengr, cleanliness is my first thought.

If you overlay a second pass of 625 do you still get cracks? Is it related to chemistry of heat input would be my next question.

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