Studies On Defects Influences On The Material Properties Of Magnesium Alloy

Magnesium alloy,with its excellent physical and mechanics properties,has been widely used in the practical engineering.However,the existence of defects in the procedure of magnesium alloy casting,which may lead to failure in projects,hinders its development in engineering applications.In this paper,finite element simulation and experimental researches on magnesium alloys with defects of segregation and porosity are carried out to investigate their influences on the macroscopic mechanical properties.The main content is summarized as follows:The first chapter introduces the significance of research on material defects.The classification,forming process and material defects are summarized.The nondestructive testing technology,material plasticity theory and finite element method theory used in this paper are introduced.The second chapter outlines the basic equations of two-dimensional elastic mechanics problems.The elasto-plasticity of circular hole defects are analyzed.Meanwhile,the influence of temperature on the elastic modulus of the material is considered.The creep theory of the alloy at high temperature is presented.In the third chapter,the Matlab software is used to model randomly distributed defects of porosity.The ABAQUS finite element software is applied to simulate stress field.The influences of radius and content of defect on the macroscopic mechanical properties of the magnesium alloy are analyzed.Simultaneously,the thermal stress of this model is analyzed,and its influence on the thermal stress of the magnesium alloy is discussed.In the fourth chapter,finite element simulation of segregation defects is carried out to discuss the influence of size and distribution of defects on macroscopic mechanics properties.The thermal stress of the segregation defect material is analyzed and its influence on thermal stress is discussed.In the fifth chapter,the mechanical experiments of magnesium alloy material containing porosity defects and segregation defects are carried out to measure the mechanical properties parameters of magnesium alloys with various grades of porosity and segregation defects,including defect-free grades.The effects of defects types and their grades(contents)are discussed.Then,the magnesium alloy are tested under high temperature to investigate the effect of temperature on the mechanical properties of the magnesium alloy with defects.Chapter Six summarizes and forecasts the full text work.