Jing-bo Wang

Analytical Evaluation of Hydrogen Embrittlement Type SCC and It's Mechanism in Duplex Stainless Steel weldment. A Study of Mechanism of HESCC in Duplex Stainless Steel and It's Welds.

In this paper, the mechanism for hydrogen embrittlement type stress corrosion cracking (HESCC) in duplex stainless steel and its weld metal was studied by using facet pit method. It was found that ferritic phase fractured in quasi-cleavage mode and austenitic phase in ductile mode. From the morphologies of facet pits formed on the fracture surfaces in ferritic phase, it was clarified that fracture planes in ferritic phase were mainly constituted of {100} plane in lower stress intensity region, and {110}, {112} plane in higher one. Consequently, the mechanism for HESCC in duplex stainless steel was explained by lattice decohesion at lower stress intensity and fracture on slip plane at higher stress intensity. From the view point of mechanism for HESCC, it was clear that the criterion for HESCC initiation mentioned in the former report (Report-3) was suitable for the lower stress intensity.

Fractographic Study on the Mechanism for Hydrogen Embrittlement Type Stress Corrosion Cracking in Duplex Stainless Steels.

The mechanism for hydrogen embrittlement type stress corrosion cracking (HESCC) in a duplex stainless steel and its welded joints was studied by facet pit method. From the fractographic observation on the fracture surfaces of base and weld metals, it was found that the ferritic phase fractured in quasi-cleavage mode and the austenitic phase in ductile mode. The weld metal was more susceptible to HESCC than base metal. From the morphologies of facet pits formed in the ferritic phase on the fracture surface, it was clarified that the fracture planes in the ferritic phase were mainly along {100} plane in the lower stress intensity region but became {110} or {112} plane in the higher one. Consequently, the mechanisms for HESCC in duplex stainless steel contain lattice decohesion at lower stress intensity and slip-off at high stress intensity.