Hardness Before And After Welding

If the welding is performed with a qualified Weld Procedure Specification (WPS), then the temperature-dependent ductile-brittle transition has been proven acceptable by Charpy V Notch testing in accordance American Society of Mechanical Engineers (ASME), Boiler and Pressure Vessel Code (BPVC), Section 9; or the appropriate American Welding Society (AWS) code, e.g. AWS D1.1.

Post Weld Heat Treating (PWHT) will also be specified by the WPS or other engineering document. If the PWHT was carried out as specified the the acceptance criteria is met. Satisfactory results of final inspection by the specified Non-Distructive Examination (NDE) Method is required for Acceptance.

If these codes are not relevant to your country there must be some equivalent method of qualifying a weld procedure.

Normally the project specifications require it AFTER. This to ensure the final hardness. I usually do a spot before to verify the effect achieved with the PWHT.

My view is that the PWHT have been ends when the hardness Test results are approved.