摘要
缩松是铸造生产中难以避免和消除的缺陷,会降低铸件的致密度和使用寿命。改进铸造工艺可有效防止和减少缩松,但难以根除。研究缩松材料变形与致密化行为,可为通过塑性变形有效压实缩松提供理论参考。本文基于孔隙均匀,基体为各向同性的理想刚塑性材料的假设,从缩松孔洞屈服准则的基本形式出发,求解了致密化过程中主应力空间内的屈服表面的形状。研究表明,缩松孔洞变形与致密是同时进行的,在相对密度为ρ时,其在主应力空间中的屈服表面是一个包含于Mises屈服圆柱面的回转椭球面。随相对密度的增加,屈服椭球面不断进行非等向膨胀,并逐步逼近Mises屈服圆柱面,最终在达到致密时与Mises屈服表面重合。
The dispersed shrinkage that reduces the density and service life of casting is a defect that is difficult to avoid and eliminate in the casting production. The dispersed shrinkage cannot be thoroughly eradicated, although it can be reduced effectively by improving the casting process. In order to consolidate the porosity effectively by plastic deformation, it is necessary to study the deformation and densifying of dispersed shrinkage, which can offer theoretical reference for making technological plan. In this paper, based on the assumption that shrinkage were uniform and the parent material was isotropic ideal rigid-plastic, yield surface of the porous materials in the principal stress space was determined according to the basic form of the porous materials yield criterion. The results show that the consolidating of the porous materials occurs once the deforming began. The yield surface is a revolving ellipsoid contained in the Mises yield cylinder surface in the principal stress space at the given relative density. With the increase of relative density, the continuous expansion of the ellipsoid yield surface is non-isotropic and gradually approachs Mises yield cylinder surface, At last, the shrinkage material is densified and the yield surface coincides with together with the Mises yield surface.
作者
武建国
安红萍
WU Jian-guo;AN Hong-ping(College of Materials Science and Engineeing,Taiyuan University of Science and Technology,Taiyuan 030024,Shanxi,China)
出处
《铸造》
CAS
北大核心
2020年第12期1272-1276,共5页
Foundry
基金
山西省自然科学基金重点基金项目:复杂结构大锻件精确成形成性一体化制造技术基础研究(201601D011002)。
关键词
缩松
变形与致密
相对密度
主应力空间
屈服轨迹
dispersed shrinkage
deforming and densifying
relative density
principal stress space
yield locus
