锻件内部脆性夹杂物边界裂纹锻合的应力条件  

Stress Condition for Healing the Crack between the Inclusion and the Matrix Metal in Heavy Forgings

作　　者：任运来[1,2] 牛龙江[1] 陈志英[1] 聂绍珉[2] 王庆伟 

机构地区：[1]上海电机学院机械学院,上海200240 [2]先进锻压成形技术与科学教育部重点实验室(燕山大学),秦皇岛066004 [3]上海重型机器厂有限公司,上海200030

出　　处：《机械工程学报》2014年第22期84-89,共6页Journal of Mechanical Engineering

基　　金：上海市教育委员会重点学科建设(12AZ02);国家科技重大专项(2012ZX0410082);上海市教育委员会上海高校知识服务平台建设(ZF1225)资助项目

摘　　要：大型锻件内部脆性夹杂物边界裂纹是影响大型锻件疲劳寿命与冲击性能的主要缺陷。热锻变形过程中,脆性夹杂物周围区域的应力场是影响边界裂纹闭合的主要因素之一。为研究应力场的影响,给出平均相对球应力的定义及其数学表达式,并借助数值模拟研究不同应力场的平均相对球应力对脆性夹杂物边界裂纹的影响。结果表明,只有当脆性夹杂物周围区域的应力场的平均相对球应力代数值小于其临界值,并产生一定大小的变形量,才能使脆性夹杂物边界处的原生裂纹锻合。利用专门设计的试件和型砧,在Gleeble-3180热模拟试验机上进行热压缩变形试验,扫描电镜上观察压缩后试件内部脆性夹杂物边界裂纹的情况。试验结果支持数值模拟结果。Cracks between the inclusion and the matrix metal are major defects affecting the forgings＇ fatigue life and impact properties. In hot forging processes, the stress field around a brittle inclusion is one of the most important factors for crack coalescence. In order to study the stress field＇s influence on crack initiation, the definition of average relative spherical stress（ARSS）and its mathematical expression are given. Influences of ARSSes of various stress fields on matrix metal-brittle inclusion crack growth are investigated by way of numerical simulation. Results show that existing matrix metal-brittle inclusion cracks can coalesce only when the algebraic value of the ARSS of the stress field around the inclusion is smaller than its critical value and there exists a certain amount of deformation. Hot compression test are done using dedicated specimens and anvils on a Gleeble-3180thermo-mechanical simulator. Cracks before and after compression tests in the specimens are observed with a scanning electron microscope. Experimental results agree well with the numerical ones.

关 键 词：平均相对球应力 大型锻件 脆性夹杂物 自由锻造 数值模拟 

分 类 号：TG316[金属学及工艺—金属压力加工]