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本文分析了冷镦螺帽用60Si2MnA 钢四序冲模在使用过程中产生弯曲、镦粗、成形部分软塌和寿命不高的原因。分析指出,奥氏体化温度偏低,保温时间不足,淬火组织中存在残留碳化物,中心部分存在未溶铁素体,导致强度和硬度降低,是造成上述缺陷和寿命不高的根本原因。试验表明,60Si2MnA 钢在950℃左右高温奥氏体化,可得到明显的板条马氏体、最好的强韧性、最高的抗压屈服强度和优良的耐磨性能,采用推荐的奥氏体化温度处理60Si2MnA 钢四序冲模,得到了满意的效果,使用寿命提高两倍以上。
In this paper, the reason of bending, upsetting, soft collapsing and short life of 60Si2MnA four-step die for cold heading nut was studied. It is pointed out that austenitizing temperature is low and holding time is insufficient, residual carbides exist in the quenched structure, and undissolved ferrite exists in the central part, which leads to the decrease of strength and hardness, which is the fundamental reason causing the above defects and low life expectancy. Experiments show that 60Si2MnA steel is austenitized at about 950 ℃, and obvious lath martensite, the best strength and toughness, the highest compressive yield strength and excellent wear resistance can be obtained. The austenite Temperature treatment 60Si2MnA four-phase die, has been a satisfactory result, more than double the service life.