喷油器体中孔硬度偏低的原因和预防措施  

Analysis on Lower Hardness of Middle Hole Surface of Fuel Injector Body

作　　者：于娜红 

机构地区：[1]一汽解放事业本部发动机事业部无锡工厂,江苏无锡214063

出　　处：《热处理》2017年第6期53-57,共5页Heat Treatment

摘　　要：一种发动机喷油器体,材料为20CrMo钢,经渗碳、淬火和低温回火后发现,其中孔硬度不足。为揭示喷油器体中孔硬度偏低的原因,对制作喷油器体的原材料进行了化学成分分析,检测了毛坯件的显微组织和硬度,并对不合格的喷油器体进行了金相检验。结果表明,原材料和毛坯的质量均符合要求;但因喷油器体渗碳后出炉温度过高,导致其中孔表面脱碳,而且由于该中孔细而长,渗碳气氛流通不畅,导致渗层碳浓度偏低,这是喷油器体渗碳、淬火后硬度偏低的原因。采用乙炔真空渗碳工艺解决了喷油器体中孔硬度不足的问题。One type of fuel injector body, made of 20CrMo steel, was carburized, hardened and low temperature tempered. From quality testing it was found that the fuel injectors body showed insufficient hardness in their middle hole. In order to disclose the reason why hardness of the middle hole of the fuel injector body was on the low side, the raw material of which the fuel injector body was made was subjected to chemical composition analysis, the blank was subjected to microstrueture survey and hardness measurements, and the unacceptable fuel injector body was subjected to metallographic examination. The results indicated that both the raw material and the blank conformed with the quality requirements, however, the middle hole of the fuel injector body offered surface decarburization which stemmed from being prematurely removed from the furnace after carburizing, and insufficient case carbon content which stemmed from the failure of carburizing atmosphere to pass adequately through it because of slender size. The surface deearburization and lower case carbon content caused the middle hole of fuel injector body to exhibit insufficient hardness after earburizing and hardening. This problem has been removed by the use of a vacuum carburizing with acetylene gas.

关 键 词：喷油器体 硬度 真空渗碳 乙炔 

分 类 号：TG115.2[金属学及工艺—物理冶金]