M2铸造高速钢的变质研究

MODIFICATION OF M2 CAST HIGH SPEED STEEL

研究了ＲＥ－Ａｌ－Ｂ－Ｔｉ复合变质对Ｍ２铸造高速钢凝固组织以及加热过程中共晶碳化物的分解与粒化的影响．结果表明，变质使该钢铸态组织得到细化，共晶碳化物呈断续网状分布，以Ｍ２Ｃ为主，ＭＣ有所增加；变质使Ｍ２Ｃ经８５０℃，３ｈ加热即发生分解并粒化，经１０００℃，３ｈ退火，晶界碳化物大量溶解；变质Ｍ２钢的淬火、回火组织中，碳化物呈粒状弥散分布，因而冲击韧性大大提高，并具有较高的硬度和红硬性。

The solidification microstructrues and the effect of heat treatment on the eutectic carbides of M2 cast high speed steel modified with RE-B-AI-Ti compound were investigated. The solidification microstructures may be refined by modification and the eutectic carbides, mainly M2C, present discontinuous network distribution. The amount of carbide MC may be increased. Decomposition and granulation of M2C may take place after annealing at 850℃ for 3 h. Annealed further at 1000℃ for 3 h, a large quantity of eutectic carbides dissolved into the matrix. The carbides occur as the granular dispersion in traditional quenching and tempering modified steel. Thus, a great improvement of the impact toughness and the hardness and red hardness may be obtained.