合金元素Mo和V对模具钢组织性能的影响

Effect of Mo and V on the Microstructure and Property of Mould Steel

本文采用C-Mn、C-Mn-V和C-Mn-Mo三种试验钢,研究了Mo和V元素对模具钢组织和性能的影响,同时研究了三种试验钢在不同回火工艺下硬度和显微组织的变化规律。研究结果表明:Mo元素能有效推迟高温转变,降低马氏体开始转变温度,促进贝氏体转变,V元素有利于粒状贝氏体的形成;试验钢组织中残余奥氏体的分解,马氏体回火转变,贝氏体铁素体板条的回复和再结晶,碳化物聚集长大等导致试验钢硬度随回火温度的升高而降低;在530℃以下回火时,Mo对贝氏体铁素体板条的回复和再结晶具有抑制作用,有利于提高钢板的回火稳定性;V在回火过程中析出细小弥散的V(C,N),起到明显的析出强化作用,显著提高试验钢的回火稳定性,同时V(C,N)析出后钉扎铁素体板条界,抑制了贝氏体铁素体板条的回复和再结晶。

C-Mn, C-Mn-V and C-Mn-Mo steels have been adopted in order to study the effects of Mo and V on the microstructure and properties of mould steel and to discuss the change law of hardness and microstructure of the three steels under different tempering processes. The results show that Mo can effectively postpone the high temperature phase transformation, reduce the starting transition temperature of martensite, and boost the bainite transition, and V can facilitate the forming of granular bainite; hardness of tested steels decrease when the tempering temperature turns higher due to the resolution of residual austenite, the tempering transition of martensite, the recovery and recrystallization of bainite ferrite lath, the growth of carbides etc. ; when tempering temperature is less than 530℃ , Mo can restrain the recovery and recrystallization of bainite ferrite lath which increases the tempering stability of steel plates; V can precipitate fine dispersive V （C, N） during tempering, which increases the tempering stability of steel plates remarkably, meanwhile the precipitated V （C and N） can pin down ferrite lath boundary, which restrains the recovery and recrystallization of bainite ferrite lath.