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我厂生产的精密机床丝杠,多用调质状态的高碳钢制成。调质用的原材料未经改锻过,尺寸为φ40×600～1500mm。具体调质处理工艺是:830～840保温1小时淬水-油冷却,640～650℃回火10小时。希望得到分布均匀的小球状珠光体及颗粒状的二次碳化物。硬度HB200～230。但最近二、三年来,曾多次出现渗碳体的石墨化现象,影响了产品的质量,也使工厂蒙受了损失。为此,我们化了二、三年的时间,研究了石墨化产生的规律、机理及其防止措施等,取得了明显的效益。
I plant the precision machine screw, multi-use state of the quenched and tempered high-carbon steel. Quenched and tempered raw materials without modification, the size of φ40 × 600 ~ 1500mm. Specific quenching process is: 830 ~ 840 1 hour quenching - oil cooling, tempering 640 ~ 650 ℃ 10 hours. Hope to get a uniform distribution of small spherical pearlite and granular secondary carbides. Hardness HB200 ~ 230. However, in recent two or three years, there have been many occurrences of graphitization of cementite, affecting the quality of the products and causing losses to the factory. To this end, we have two or three years to study the law of graphitization, mechanism and prevention measures, and achieved significant benefits.