硅对热处理态M2高速钢中共晶碳化物的影响

Effect of silicon on the eutectic carbides in as-heated M2 high speed steel

通过电渣重熔制备不同硅含量的M2高速钢铸锭(硅质量分数分别为0.3%,0.8%,1.6%和2.4%),采用光学显微镜(OM)、扫描电镜(SEM)、能谱分析(EDS)和X射线衍射(XRD)的方法研究了硅对热处理态M2高速钢中共晶碳化物的影响。研究结果表明,退火态高速钢铸锭中共晶碳化物呈连续或半连续网状分布于枝晶间,随着硅含量的增加,共晶碳化物从片层状M2C变为鱼骨状M6C。在1 165℃保温2.5h的热处理过程中,片层状M2C碳化物分解为MC和M6C碳化物,在后续变形中破碎为细小的碳化物颗粒。0.8%Si的加入减小了M2高速钢中碳化物的尺寸,而高硅含量高速钢中由于鱼骨状M6C碳化物在热处理过程中并没有发生转变,经后续变形后仍有尺寸较大对性能不利的块状碳化物。

The effect of silicon on the eutectic carbides in as-heated M2 high speed steels is investigated by using optical microscope,scanning electron microscope,energy dispersive spectrometer and X-ray diffraction analysis.The high speed steel ingots with different silicon additions are produced by electroslag remelting process（the mass content of silicon is 0.3%,0.8%,1.6% and 2.4%,respectively）.The ingots are annealed at 780 ℃ for 10 h and heated at 1 165 ℃ for 2.5 h.The results show that the eutectic carbides distributed in the dendrites with continuous or semi-continuous net-shape in the as-annealed ingots.The eutectic carbides change from lamellar-like M2C to herringbone-like M6C with the increase of silicon content.After 2.5 h heating at 1 165 ℃,the lamellar-like M2C decomposes into granular M6C and MC,and the size of granules in M2 high speed steel ingot with 0.8%Si addition is smaller than that in the 0.3%Si.Whereas herringbone-like M6C is unchanged during heating treatment,and coarse primary blocky carbides which are harmful for properties still exists after the deformation.