Prior Austenite Grain Xize and Segregation Behaviour in 2.25Cr-1Mo steelPrior Austenite Grain Xize and Segregation Behaviour in 2.25Cr-1Mo steelPrior Austenite Grain Xize and Segregation Behaviour in 2.25Cr-1Mo steel

摘要

In the case of 2.25Cr-1Mo steel for fast fracture, it has been found that the brittle fracture behavior can be changed from its typical transgranular cleavage fracture to intergranular decohesion, if the impurity element segregation level at prior austenite grain boundaries exceeds a certain critical value. This change in fracture mode can also decrease the fracture stress value and enhance the crack growth rate. Among many parameters that control the impurity element segregation behaviour in steel, prior austenite grain size is a very important one. In this present work the influence of austenite grain size on the degree of temper embrittlement of 2.25Cr-1Mo steel has been studied by measuring the microscopic fracture stress (OF) values at low temperature and observing the proportion of intergranular fracture in the SEM.