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机械零件在渗碳淬火的热处理过程中,炉前金相检验是不可缺少的重要环节.我厂生产的20CrMnTi钢制零件(如汽车变速箱齿轮等)渗碳工艺是在滴注式井式气体渗碳炉内进行的.按常规的金相检验方法是:齿轮试样随工件一同进行渗碳淬火后(采用渗碳后直接淬火),用金相切割机切下一个齿,再将这个齿从中间切为两半,一半齿制成金相试样,在金相显微镜下检验淬火组织及测定有效硬化层(根据GB9450—88标准);另一半齿退火后得到平衡组织,用来检验渗碳层深度和浓度梯度.
Mechanical parts in the carburizing and quenching heat treatment process, the pre-test metallurgical inspection is an indispensable part of my factory production 20CrMnTi steel parts (such as automotive gearbox gear, etc.) carburizing process is instill type gas Carburizing furnace carried out by conventional metallographic test methods are: with the workpiece after the gear sample with carburizing and quenching (carburizing directly after quenching), with a metal cutting machine cut a tooth, and then the tooth Cut in half into the middle, half of the teeth made of metallographic specimens, the microstructure of quenched microstructure and the determination of the effective hardened layer (according to GB9450-88 standard); the other half of the teeth after annealing equilibrium, to test the seepage Carbon depth and concentration gradient.