numberfive
Mechanical
- Mar 18, 2011
- 48
Experts,
We recently completed welded repairs to an A-217 Gr. WC6 cast part for a high pressure boiler main steam application.
To make a long story short, our PWHT contractor inadvertently ran the part through the wrong heat treatment cycle with a batch of other parts.
The part should have been PWHT'd at 1,250 deg. F for 1hr. per ASME B31.1 rules. Instead the part was heated to 1,550 deg. F, held for 2hrs and then oil quenched.
Going on advice from their metallurgist as well as a third party metallurgist we were advised to again bring the part to 1,500 deg. F this time allowing to cool to ambient temperature in still air (essentially normalize) to correct any unwanted hardening that may have taken place due to the oil quench with the first heat treatment cycle.
I requested that several hardness readings be taken after this second "normalizing" heat treatment. The resulting (6) tests were all between 70 - 80 HRB. This seems unusually soft to me.......should I be concerned?
Does a reduction in hardness have a direct correlation to a reduction in strength?
To complicate matters this is a decades old part for which the owner has no material test reports that may tell us what the hardness was when it was new.
Any insight would be greatly appreciated.
numberfive
We recently completed welded repairs to an A-217 Gr. WC6 cast part for a high pressure boiler main steam application.
To make a long story short, our PWHT contractor inadvertently ran the part through the wrong heat treatment cycle with a batch of other parts.
The part should have been PWHT'd at 1,250 deg. F for 1hr. per ASME B31.1 rules. Instead the part was heated to 1,550 deg. F, held for 2hrs and then oil quenched.
Going on advice from their metallurgist as well as a third party metallurgist we were advised to again bring the part to 1,500 deg. F this time allowing to cool to ambient temperature in still air (essentially normalize) to correct any unwanted hardening that may have taken place due to the oil quench with the first heat treatment cycle.
I requested that several hardness readings be taken after this second "normalizing" heat treatment. The resulting (6) tests were all between 70 - 80 HRB. This seems unusually soft to me.......should I be concerned?
Does a reduction in hardness have a direct correlation to a reduction in strength?
To complicate matters this is a decades old part for which the owner has no material test reports that may tell us what the hardness was when it was new.
Any insight would be greatly appreciated.
numberfive
