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用三点弯曲疲劳试验测定了M2高速钢和含铌基体钢等三种工模具材料的疲劳裂纹扩展速率da/dN和门坎值ΔK_(th)并从合金成分和热处理工艺角度分析了显微组织的影响。试验结果表明,ΔK_(th)随基体韧性的皮善、残余奥氏体量的增加和晶粒尺寸的增大而提高。中速区的da/dN主要取决于基体韧性的好坏,较多韧性相使其减小,较大碳化物使其增大,而晶粒尺寸对其影响不明显。
The fatigue crack growth rate da / dN and threshold value ΔK th (th) of three kinds of tool materials, such as M2 high speed steel and niobium-containing matrix steel, were measured by three-point bending fatigue test and the microstructure was analyzed from the aspects of alloy composition and heat treatment process Impact. The experimental results show that ΔK_ (th) increases with the increase of matrix toughness, retained austenite content and grain size. The da / dN in the medium speed zone mainly depends on the toughness of the matrix, more ductile phase makes it smaller, bigger carbides make it bigger, while the grain size has no obvious effect on it.