Abstract
An investigation has been made into the analysis of the fracture morphology of hydrogen embrittlement for a quenched and tempered Cr-Mo steel. The Cr-Mo steel showed the tempered martensite embrittlement by 300°C tempering treatment.
The susceptibility to hydrogen embrittlement was highest for the as-quenched specimen, and decreased with increasing tempering temperature. The ratio of intergranular fracture in the fractured surface was highest for the specimen tempered at 300°C.
The fracture morphology of tempered martensite embrittlement was intergranular fracture with flat surface, but the morpholgy of hydrogen embrittlement was intergranular fracture with tear ridges on the surface. The characteristic morphology of hydrogen embrittlement was quasi-cleavage fracture due to hydrogen (QCHE), which had the same small facet size as martensite lath morphology, with secondary cracks along the martensite lath. This fracture morphology was the same as that of hydrogen embrittlement of HT80 steel previously indicated.
