我厂加工一批BJ—130型汽车变速器齿轮(18CrMnTi固体渗碳淬火),在装配过程中发生崩齿现象。经过金相分析,发现这批齿轮过共析区碳化物呈大块密布(如图1),接近共析区碳化物呈网状和半网状(如图2)。参照第一汽车制造厂18CrMnTi渗碳齿轮金相标准,碳化物评定为7级。根据碳化物等级和分布状态,这批齿轮应报废。 I plant a group of BJ-130-type automotive transmission gear (18CrMnTi solid carburizing and quenching), the collapse occurs during the assembly process. After metallographic analysis, it was found that these gears eutectic carbides were large and dense (Figure 1), carbide near the eutectoid was reticular and semi-network (Figure 2). Reference to the first car manufacturer 18CrMnTi carburizing gear metallurgical standards, carbide was rated 7. Depending on carbide grade and distribution, these gears should be scrapped.