W6Mo5Cr4V2Al高速钢麻花钻断裂原因分析

Fracture cause analysis of W6Mo5Cr4V2Al high speed steel twist drill

利用化学成分分析、光学显微镜、扫描电镜以及能谱分析等手段研究了W6Mo5Cr4V2Al高速钢麻花钻的断裂原因。结果表明,麻花钻在热处理过程中发生过热、过烧,导致局部晶界熔化,基体内形成共晶莱氏体和大量网状碳化物,冷却时在表面形成较高的拉应力,当应力大于材料的断裂强度时产生沿晶裂纹,在随后的校正过程中,在外力作用下发生了断裂。

Fracture causes of W6Mo5Cr4V2Al high speed steel(HSS)twist drill were studied by means of chemical composition examination,OM,SEM and EDS.The results show that the overheating and overburning of the twist drill caused in the heat treatment processes lead to grain boundary melting,eutectic ledeburite and a large number of reticulated carbides in the matrix,and high tensile stress formed on the drill surface in the cooling process leads to intergranular crack to appear when the stress is higher than the fracture strength of the material,finally the action of external force in the subsequent correction process causes the fracture of the drill.