More on Stellite Hardfacing 1

[tc7]

This question pertains to Stellite #6 hardfacing (GTAW process)on a forged steam valve disc (ASTM A182, grade F22V). Following the strong advice offered on thread 330-179624, i.e., to completely remove the Stellite layer in lieu of repairing cracks, we had to hand grind down to base material by hand, leaving rough and uneven surfaces. Starting from the unequal and unsmooth surfaces (with some gouging)for our hardfacing, we will end up with some variations in thicknesses of the final machined Stellite, but well within the maximum Stellite thickness in our WPS and PQR.

My question is this: Would it be preferred to
A. Restore a smooth uniform surface on the disc base metal by building up with another filler (ER90S ??), then machine down to a smooth base prior to Stelliting?
or B. Work with the uneven base and buildup with Stellite to the desired final dimension, even though Stellite thickness will not be uniform.

Thanks for all interest and advice!

 

[EdStainless]

I like the 309 inter layer. it lets you even things up and keep the hardfacing application constant.

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[metengr]

tc7;
Go with Option A. I would use Inconel 82 as a butter layer over the rough F22V surface. I prefer Ni-base filler metals because they have a lower carbon diffusivity and less chance for carbon migration along the fusion zone of the weld. I limit 309 filler metals to 800 deg F or less in dissimilar metal welds.