灰铸铁件机加工困难问题分析  

Analysis of Difficulties in Machining Gray Cast Iron

作　　者：尹鸿祥[1] 赵爱民[1] 胡汉江[1] 张岩[1] 周开春[1] 杨梅梅 

机构地区：[1]北京科技大学冶金工程研究院现代交通金属材料与加工技术北京实验室,北京100083 [2]唐山志威科技有限公司,河北唐山064200

出　　处：《铸造技术》2014年第12期2988-2991,共4页Foundry Technology

摘　　要：为解决某公司灰铁铸件生产中的机加工困难问题,进行了铸造生铁和铸件的成分分析,并对铸件进行了光学显微镜、扫描显微镜、布氏硬度、显微维氏硬度以及能谱分析。结果表明26#生铁P,S含量偏高,22#生铁Si含量偏低,不满足标准。铸件碳当量为4.36%,属于高碳当量铸件;Si/C比为0.46,偏低。铸件成分中Si、Mn含量偏低,Cr含量偏高,已经足以产生白口化,且含有V元素。铸件组织为铁素体、珠光体、石墨和碳化物。其中部分碳化物中含有Cr、V等微合金元素,显微硬度超过1 100 HV,是引起机加工困难的主要原因。因此,为改善机加工,首先应使铸造生铁成分合格,应该使Cr、V含量不超标准。其次,提高Si含量,首选孕育法加入Si。对于要求严格的铸件,可进行石墨化退火,使碳化物分解。In order to solve the machining problems of gray iron casting in a company, the components and properties of foundry pig and castings were analyzed by optical microscope, scanning electron microscope, Brinell hardness, micro Vickers hardness and spectrum analysis. The results show that the content of S and P of 26# pig iron was above the high side, the content of Si of 22# pig iron is low, so the chemical compositions do not satisfied criteria. The carbon equivalent of the castings is 4.36%, which is belonging to high carbon equivalent castings. The ratio of Si and C is 0.46, which is on the low side. The content of Si and Mn in the casting is low, in addition to the content of Cr is high, which is sufficient to produce chilling phenomenon, there is V element in the more castings, the microstructure of the casting is ferrite, pearlite, graphite and carbide. Some part of the carbide contains Cr, V and other micro-alloying elements, and the micro hardness is over 1 100 HV, which is the main cause of machining difficultly. Therefore, in order to improve the machining capacity, firstly, the content of V and Cr should not exceed the standard. Second, the content of Si should be increased and should first choose to add in inoculatiorL For demanding castings, the carbide can be decomposed by graphitizing annealing.

关 键 词：灰口铸铁 白口化 机加工 合金渗碳体 

分 类 号：TG143.2[一般工业技术—材料科学与工程]