strider6 - I agree with your statement re: WPS. In an earlier post, you stated:
"... WPS / PQR tells you that if you do the weld following the WPS you'll have always hardness within the limits".
However SJones stated:
"the PQR in no way guarantees that the final weld has a hardness that meets ISO 15156-2 requirements unless it has been made in material from the same heat of steel and welding parameter variation was totally negligible".
I tend to agree with Strider6 because you are always going to get variations of the heats and welding parameters between the PQR and production. The essential and nonessential variables of the WPS should address those variations.
The point I was trying to make, regarding SJones, is if I can't guarantee conformity of my production welds by following my WPS, then what is the purpose of the WPS and the PQR?
According to ASME Section IX: "The purpose of the Welding Procedure Specification (WPS) and Procedure Qualification Record (PQR) is to determine that the weldment proposed for construction is capable of having the required properites for its intended application" Therefore, why would I need to perform post hardness if my PQR results come in well under 250HV?
If I can relate this to impact testing, our WPS addresses notch toughness to -50F. If my base material is charpy tested to -50F and I use this WPS, I do not have to perform production impact testing on the weldment. My hardness on the PQR came in at around 160HV (<250HV), therefore, by the same reasoning, I shouldn't have to perform production hardness testing.