热处理对超硬高速钢M42冷拔材组织和塑性的影响

Effect of Heat Treatment on Microstructure and Plasticity of Cold-drawn Finished Products of Super-Hard High-Speed Steel M42

采用中间退火、炉冷退火及相变退火等工艺处理W2Mo9Cr4VCo8(AISI M42)超硬高速钢冷拔钢丝(Φ5.2 mm、Φ4.96 mm),研究分析了不同组织因素对M42材料形变硬化和塑性的影响规律。结果表明,位错密度、铁素体晶粒度及亚微米级碳化物,在不同程度上影响M42高速钢形变硬化和塑性失稳行为。800℃中间退火和860炉冷退火能够显著降低铁素体位错密度,在一定程度上恢复加工硬化能力、改善M42高速钢加工塑性。860℃加热+750℃等温相变退火能够获得低位错密度、细小晶粒内部弥散分布亚微米碳化物颗粒的均匀复相组织,有利于提高材料加工硬化能力,使M42钢延伸率提升至20%。

W2Mo9Cr4VCo8(AISI M42) super-hard high-speed steel wires(Φ5.2 mm,Φ4.96 mm) are treated by intermediate annealing,furnace-cooling annealing and phase-transformation annealing,and the effect of different microstructure factors on work hardening and plasticity of M42 is studied.The result shows that dislocation density,submicron carbide and ferritic grain size play different roles in work hardening and plastic instability of M42 high-speed steel.Intermediate annealing at 800℃and furnace-cooling annealing at 860℃can significantly reduce the ferrite dislocation density,restore the work hardening ability to some extent,and improve the plasticity of M42 steel.By contrast,austenitizing at 860℃ followed by isothermal annealing at 750℃ can obtain a large number of submicron carbides embedded in fine ferritic grains with a very low dislocation density,which is available to enhance work hardening rate and increase elongation of steel M42 to20%.