淬火温度对高硼高速钢显微组织的影响

在普通高速钢材料中,加入适量硼来取代普通高速钢中价格昂贵的合金元素,设计了一种新型的高硼高速钢材料。研究了淬火温度对0.4%～0.5%C和1.0%～1.5%B的高硼高速钢显微组织的影响。结果表明,高硼高速钢的铸态组织由铁素体、珠光体和少量马氏体以及硼碳化合物组成,硼碳化合物由M23(B,C)6、(W,Mo)2(B,C),M3(B1.5,C0.5)和M(B0.7,C0.3)组成,呈网状和鱼骨状沿晶界分布。淬火处理后,基体组织转变成板条马氏体,含有4%残留奥氏体,硼碳化合物的类型没有发生变化,但数量减少。在950～1100℃内淬火,硼碳化合物局部发生溶解,出现断网现象;随着淬火温度的升高,断网现象越来越明显,从而减轻了对基体的割裂作用。

Effect of quenching temperature on microstructure of high-boron high speed steel

A novel high-boron high speed steel was developed by addition of boron to replace the expensive alloying elements in commerical high speed steel material.The effect of quenching temperature on microstructure of high-boron high speed steel containing 0.3-0.5%C and 0.5-2.5%B was studied.The results show that the as-cast microstructure of the high-boron high speed steel consists of ferrite(F),pearlite(P) and a small amount of martensite(M) and borocarbides of M23(B,C)6,(W,Mo)2(B,C),M3(B1.5,C0.5) and M(B0.7,C0.3),distributing in network and herringbone along grain boundaries.After quenching,the matrix microstructure changes to lath martensite containing 4% residual austenite.There is no change in the type of borocarbide,but its quantity decreases.Quenching from temperature of 950-1100 ℃,the network pattern is broken because of partial dissolution of borocarbides.As the quenching temperature increases,phenomenon of the network breaking become more and more obvious,which reduces the dissevering to the matrix of high-boron high speed steel.