Effects of W and Mn on the mechanical properties, microstructure and aging behaviors of 10% Cr ferritic steels considered as reduced radio-activation materials

Abstract

The effects of W and Mn alloying elements on the microstructure, mechanical properties and aging behavior of 10% Cr ferritic stainless steels were investigated. Tensile strength and hardness after tempering and/or aging treatment increased gradually with increasing Mn content, but the effect of W additions was very small. Mn and W, however, had large effects on the Charpy absorbed energy. The absorbed energy after tempering and/or aging treatment decreased with increasing Mn content. But as for the effect of W, Charpy absorbed energy had maximum peaks at 1% W addition for all 10Cr-0 to 5 Mn (mass%) steels. The fracture mode of the impact test at room temperature was complex. Martensitic materials showed intergranular brittle fracture after tempering but ductile fracture after aging treatment. Dual phase material which contains a ferritic phase and a martensitic phase indicated ductile fracture after tempering, but transgranular cleavage fracture occurred after aging. It was concluded that 1% W addition would be most appropriate to 10Cr-0 to 5Mn-0.08C ferritic steels from the points of view of hardness, tensile strength, Charpy absorbed energy and fracture mode.