Hot Straining Embrittlement of Coarse Grained HAZ (Ist Report)

Evaluation of the Susceptibility to Hot Straining Embrittlement by Means of BNP Specimen with Angular Distortion

Abstract

A new test method to assess the susceptibility of coarse grained HAZ to hot straining embrittlement has been proposed. Hot straining embrittlement of the coarse grained HAZ in HT80, A533 and SM50 steels has been evaluated.
Results can be summarized as follows:
(1) The susceptibility of coarse grained HAZ to hot straining embrittlement can be easily assessed by using BNP specimen (three points bend specimen with notch of poor penetration) with angular distortion.
(2) The degree of hot straining embrittlement has been analyzed quantitatively as a function of angular distortion of the joint.
(3) The susceptibility to hot straining embrittlement in SM50 steel increases with increasing heat input of the joint.
(4) Thermal stress relief has advantage effect on the coarse grained HAZ's fracture toughness in SM50 steel embrittled by hot straining, but it has disadvantage effect on the HAZ's fracture toughness in A533 steel embrittled by hot straining. For A533 steel, stress relief embrittlement is superposed on hot straining embrittlement.