Effect of Morphology for Novel Bainite/Martensite Dual-Phase High Strength Steel on Its Hydrogen Embrittlement Susceptibility

It is very imperative to study the novel highstrength materials with high purity,high uniformityand refined grain,for improving the utilization rateand quality of materials.However,improving thestrength will reduce the resistance of materials tohydrogen embrittlement. For example,in lastcentury,some hydrogen embrittlements in thelanding gear of plane were reported[1] . When yieldstrength exceeds 1380 MPa,high strength steelsbeing used now exhibit strong susceptibility tohydrogen embrittlement…

Effect of Morphology for Novel Bainite/Martensite Dual-Phase High Strength Steel on Its Hydrogen Embrittlement Susceptibility

The susceptibility to hydrogen embrittlement of bainite/martensite dual phase high strength steel with different morphologies obtained by the conventional and thermo mechanical heat treatments has been investigated by means of electrolytic hydrogen charging. The results showed that the finer the microstructure, the lower the sensitivity of steel to hydrogen embrittlement. The fractographic analysis suggested that the fracture mode of the hydrogen charged specimens is of a mixture of quasicleavage and dimple for both treating processes. The quasicleavage facet of the thermomechanical treated specimen is smaller than that of the conventional heated one, which is probably the reason for reducing the susceptibility to hydrogen embrittlement. Fracture metallographic observations showed that the crack propagates preferentially along bainite/martensite laths boundary, and suggested that the fracture mode is of predominantly lath boundary separation.