发动机排气门用钢5Cr21Mn9Ni4N中的M_7C_3相与热裂纹原因探讨  

Discussions on the M7C3 Phase in Steel 5Cr21Mn9Ni4NUsed for Engine Exhaust Valve and Cause of Hot Crackle

作　　者：刘祖林[1] 牛龙江[1] 范宏利 叶卫平[1] 

机构地区：[1]武汉汽车工业大学

出　　处：《汽车技术》1996年第12期40-44,共5页Automobile Technology

摘　　要：分析和测定了５Ｃｒ２１Ｍｎ９Ｎｉ４Ｎ钢中Ｍ７Ｃ３相的形貌特征及化学组成，并对钢中钙含量与Ｍ７Ｃ３相及铸、锻件热裂纹的关系进行了探讨。当该钢中钙含量大于０．００６８％及铸锭冷却过缓时，就易在该钢中形成大而脆的Ｍ７Ｃ３的晶界薄膜，使铸、锻件常常出现热裂纹。Morphological characteristic and chemical composition of M 7C 3 phase in the steel 5Cr21Mn9Ni4N have been examined and analysed,and relations between calcium content in the steel and M 7C 3 phase as well as hot crackle in casting and forging parts are looked into.It is understood consequantely that large and brittle crystal boundary film of M 7C 3 might grow easily in the steel,which causes hot crackle to appear occassionally in casting and forging parts if calcium content in the steel would be more than 0.0068% and cooling speed of ingot casting too low.The hot crackle can be only eliminated by lowering mainly calcium content in the steel.

关 键 词：气门 5CR21MN9NI4N钢 M7C3相 汽车发动机 裂纹 

分 类 号：U464.134.3[机械工程—车辆工程]