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我厂拖拉机二轴系20CrMnMo钢制造,在渗碳后曾几次发现纵向裂纹,经对实物作金相分析和工艺试验证实是由渗碳后冷却速度不当所致。改变了渗碳后的冷却速度,顺利地解决了表面开裂的问题。一、渗碳情况渗碳设备采用RJJ75-9T,渗碳剂为煤油,渗碳温度930℃。渗碳后在冷却桶中冷却,为减少在冷却过程中析出网状碳化物,冷却桶四周隔层内通水;为了防止工件在冷却过程中氧化脱碳,在冷却桶底部放一砂盘,砂盘内倒入甲醇,利用工件的热量使甲醇热解而得以实现。二轴渗碳深度要求为0.8～1.2mm,其它技术条件按JB1673-75标准检查。渗碳时将二轴放在专用挂具上,专用挂具分二层,
I plant tractor shaft 20CrMnMo steel manufacturing, found several times in the carburizing longitudinal cracks, after the physical and metallurgical analysis for the test proved to be due to the cooling rate after carburizing due to improper. Change the cooling rate after carburizing, smooth solution to the problem of surface cracking. First, the carburizing situation Carburizing equipment used RJJ75-9T, carburizing agent for kerosene, carburizing temperature 930 ℃. After carburizing and cooling in the cooling barrel, in order to reduce the precipitation of reticular carbides in the cooling process, the cooling water is circulated in the compartment around the cooling barrel; in order to prevent the workpiece from oxidative decarburization in the cooling process, a sand disc is placed at the bottom of the cooling barrel, Placed in the sand into the methanol, the use of the heat of the workpiece so that methanol can be achieved pyrolysis. Biaxial carburizing depth requirements of 0.8 ~ 1.2mm, other technical conditions by JB1673-75 standard inspection. Carbide will be placed on the two-axis special hanging on the special linked to the second floor,