M42高速钢中的碳化物

CARBIDES IN HIGH SPEED STEEL M42

本文用金相显微镜和扫描电镜等方法研究了M42高速钢中的碳化物。M42的铸态共晶碳化物主要是以片状和条状为基本单元的M_2C,他们组成了多种形态的M_2C共晶体。在高温下M_2C不稳定,分解转变成M_6C和MC。由M_2C的分解,使M42钢中的碳化物颗粒尺寸较细,分布较好。但残存的M_2C颗粒一般较粗,形状不规则,易裂造成M42钢的锻材、轧材、冷拔材和冷拔丝中均存在微裂纹。文中指出,应设法促使铸态M_2C碳化物尽早彻底转变,并提出了有效措施。

Carbides in high speed steel M42 have been studied by means of SEM and metallograph. The carbide in the cast eutectic is mostly M2C with flake and strip forms which form M_2C eutectics of various types. "Labyrinth"-M_2C is unstable at high temperature and normally decompose to M_6C and MC. This decomposition makes size of the carbide finer and makes distribution of it more even. The residual M_2C grains are coarse and irregular and easily cracked. This is the reason of the cracks in M42 forgings, hot rolled bar, cold drown bar and cold drown wire. So it is necessary to promote the decomposition as complete and early as possible. Some effective measures are raised.