回火温度对新型冷作模具钢显微组织和性能的影响

由于莱氏体钢中含有大量的碳化物,常用的AISID2冷作磨具钢具有很高的耐磨性,但由此而易于崩裂且不易锻造及线切割加工。为此,调整其成分和热处理工艺而开发了一种新型模具钢(实验钢)。采用金相显微镜、硬度计及冲击实验机研究了回火温度对该新型钢显微组织硬度和冲击韧性的影响。结果表明,在1050℃淬火及500℃回火处理时,实验钢与D2钢相比所含碳化物较少且颗粒尺寸较小,而且在各种回火温度下其冲击韧性和硬度均高于D2钢。例如经500℃回火处理,其硬度与冲击韧性分别为HRC64和45J/cm2·由于排除了其中的粗大又不均匀的碳化物,实验钢组织大为改善,由此而消除了在使用中的崩裂失效现象并延长了使用寿命·

Effects of Tempering Temperature on Microstructure and Properties of a Newly Developed Cold-working Die Steel

A cold-working die steel was developed through adjusting allowing components and heat-treatment process to improve the conventional steel AISI D2 of which a lot of carbides in ledeburite offer very high wearability in combination with low impact toughness which is easy to lead D2 to break up in use and hard of forging and linear cutting. The effects of tempering temperature on the microstructure, hardness and impact toughness of the new steel (test steel) were investigated by means of metallographical microscope, hardmeter and impact taster. The results show that it has advantages of less carbides and smaller particle size if quenched at 1050°C and tempered at 500°C and its impact toughness and hardness are both higher than D2 at various tempering temperatures, e.g. HRC60 and 4.5×10⁵ J/m² at 500°C respectively. With coarse, big and uneven carbides removed, its structure is improved greatly, thus eliminating the break-up inactivation and prolonging the service life.