Effect of yttrium on mechanical properties of 9Cr-2WVTa low active martensite steel

The effect of the rare earth element,yttrium,on the mechanical properties of 9Cr-2WVTa low active martensite steel for fusion reactor was studied and the metallurgical behavior of yttrium in the steel was primarily analyzed.The results show that it is easy for yttrium to aggregate and form the blocky yttrium rich inclusions in the steel,which can dissever the continuity of the matrix and produce micro-cracks for fracture.The yttrium rich inclusions were distributed along the rolling direction,which made the fracture surface delaminated in the tensile and impact samples,and reduced the mechanical properties of the steel.