PWHT OF 304H

[weldtek]

Our customer is stipulating that PWHT is required for some 3/4" thick 304H plate on which we will be applying hardfacing. ( St. 6) They don't provide a PWHT temperature or hold time and I'm wondering if anyone has experience with PWHT on an application like this?

 

[metengr]

weldtek;
PWHT is not required. However, preheat will be required for the Stellite 6 to avoid cracks. We have applied Stellite 6 to other substrate materials, and I needed to preheat up to 600 deg F to prevent cracks after welding in the HF, there was never a need to PWHT.

 

[weldtek]

metengr
Thanks for the reply. My experience is similar. When overlaying with Stellite 6 we normally preheat to 500 F minimum and maintain that minimum temp throughout welding, then wrap and slow cool. For Stellite 1 we use 1000 F. In this case, our customer specifies that PWHT be performed prior to grinding the overlay. We're going to have a vendor put the parts on a reciprocating grinder and grind them smooth. I'm assuming our customer is looking for a thermal stabilization prior to the grinding, but, in my limited experience with thermal stabilization treatments it seems to me they're more like a ritual than a science, and I'm not sure what, if any, heat treatment will accomplish a stabilization.

 

[strider6]

PWHT (stress relieving) on an Austenitic SS steel is not used because it could produce sensitization.

S.

http://www.corrosionist.com

 

[weldtek]

A colleague referred me to the site below. Nothing really new, but, some interesting info on heat treatment of stainless steels. There are many other articles related to applications of stainless steels. Worth a look.

http://www.hghouston.com/ss_heat.html