PWHT of a572 Gr. 50 in Bifurcation sickle plates 2

[LVLIIIenger]

We have a customer that insists on PWHT of a572 Gr. 50 sickle plates of a wye Bifurcation that range from 1 1/2 " to 4" thickness per ASME sec VIII. However all the information I have found states that PWHT of a572 Gr. 50 degrades the strength and toughness. My question, and I have read what others have stated in this forum, where can I find documentation that states this information? We maintained a pre-heat of 250°F during all welding activities as well.

 

[metengr]

LVLIIIenger;
Here is what I would suggest - weld two groove weld coupons using the ASTM A 572 HSLA steel (microalloy). Leave one weld coupon as-welded, and subject the second weld coupon to PWHT. The mechanical test results regarding strength and elongation (or reduction of area) and CVN impact test results will speak volumes and settle the issue.

 

[LVLIIIenger]

Thank you sir, I will follow your suggestion.

Sam Bruno

 

[stanweld]

Highly recommend metengr's recommendations.

Whether strength and toughness will be adversely affected is highly based on whether the steel was "killed" and made to conventional fine grain melting practice or not and the microalloys used. Per A572, thickness > 1.5 inches must "killed". It is well known that toughness in the HAZ will be adversely affected in Cb & V treated steels after PWHT (raising ductile to brittle transition temperature due to secondary carbide formation). Note that the upper shelf range of absorbed energy was more than acceptable. In the 1970's we began specifying such grades as silicon killed with aluminum additions for fine grain melting and limits on Cb and V and total CB + V. These materials had no problem meeting -50 F impact toughness requirements after PWHT in the base metal and HAZ.

 

[rmw]

LVLIIIenger,

Will you be able to post back the results when you carry this off?

rmw

 

[LVLIIIenger]

Yes, I will post back results from our testing for informational use to others.

Thank you

SPB

Sam Bruno