Study of PWHT Embrittlement in High Strength Low Alloy weld Metals (paper 2)
Study of mechanism of PWHT embrittlement
1996 Volume 34 Issue 1 Pages 3-7
Details
1996 Volume 34 Issue 1 Pages 3-7
PWHT (Post Weld Heat Treatment) embrittlement phenomena were reported in the previous paper. PWHT embrittlement was found to occur along austenite grain boundaries. In this paper, mechanism of the PWHT embrittlement and the effect of alloying elements on the embrittlement are discussed.
Main conclusions derived are as follows:
1) Two types of PWHT embrittlement are observed. One is precipitation embrittlement at PWHT temperature. The other is temper embrittlement upon cooling after PWHT. Precipitation of carbonitrides and the segregation of phosphorus along austenite grain boundaries are observed in both cases.
2) Decrease in C, N and P contents improves the notch toughness of welds after PWHT. Ni is effective to increase the tensile strength of welds without the PWHT embrittlement.
