Evolution of stresses in metal injection molding parts during sintering  

粉末注射成形坯体在烧结过程中的应力演化（英文）

作　　者：方伟[1] 何新波[1] 张瑞杰[1] 杨诗棣[1] 曲选辉[1,2] 

机构地区：[1]北京科技大学新材料技术研究院,北京100083 [2]北京科技大学新金属材料国家重点实验室,北京100083

出　　处：《Transactions of Nonferrous Metals Society of China》2015年第2期552-558,共7页中国有色金属学报（英文版）

基　　金：Project(2011CB606306)supported by the National Basic Research Program of China;Project(FRF-TP-10-003B)supported by the Fundamental Research Funds for the Central Universities,China;Project(51274040)supported by the National Natural Science Foundation of China

摘　　要：The evolution of stresses due to inhomogeneity in metal injection molding （MIM） parts during sintering was investigated. The sintering model of porous materials during densification process was developed based on the continuum mechanics and thermal elasto-viseoplastic constitutive law. Model parameters were identified from the dilatometer sintering experiment. The real density distribution of green body was measured by X-ray computed tomography （CT）, which was regarded as the initial condition of sintering model. Numerical calculation of the above sintering model was carried out with the finite element soRware Abaqus, through the user-defined material mechanical behavior （UMAT）. The calculation results showed that shrinkages of low density regions were faster than those of high density regions during sintering, which led to internal stresses. Compressive stresses existed in high density regions and tensile stresses existed in low density regions. The densification of local regions depended on not only the initial density, but also the evolution of stresses during the sintering stage.研究金属粉末注射成形坯体在烧结过程中由于不均匀性导致的应力演化过程。基于连续介质模型和热弹粘塑性本构关系,建立描述孔体材料烧结致密化过程的模型。通过热膨胀试验得到模型中的材料参数,通过CT断层成像技术得到坯体的真实断面密度分布,并以此作为烧结模型的粉体含量初始分布。在有限元软件Abaqus中调用用户材料子程序(UMAT)子程序实现上述模型的数值计算。计算结果表明:烧结过程中低密度区域的烧结收缩速率大于高密度区域的收缩速率,从而导致产生内应力;高密度区域存在压应力,低密度区域存在拉应力;局部区域的致密化状态不仅与初始粉体含量相关,而且与烧结过程中的应力演化有关系。

关 键 词：metal injection molding CT detection SINTERING DENSIFICATION STRESS numerical simulation 

分 类 号：TF124[冶金工程—粉末冶金]