镁合金压铸模具热应力数值分析与试验研究OA

Suppressing fatigue damage of dies is one of the challenges in the high pressure die casting(HPDC)process design.Firstly,the isothermal tensile tests were conducted on the H13 die steel,which was used for the die casting dies,across the temperature range of 20 to 800℃to determine the yield strengths and plastic modulus at different temperatures,and the fracture mechanisms at different temperatures were confirmed according to the fracture mophologies of specimens;secondly,based on the finite element method,the numerical simulation of thermal stress field variations of casting and die casting dies during die casting process of AZ91D magnesium alloy flat piece was carried out.The calculation results indicate that the maximum temperature in the forming zone of the moving die is approximately 44.0℃higher than that in the fixed die;the maximum contact stress in the moving die is about 170.7 MPa higher than that in the fixed die;the maximum shear stress in the moving die is approximately 15.1 MPa higher than that in the fixed die.These results suggest that the moving die has a higher probability of generating fatigue damage compared wtih the fixed die.The HPDC tests indicate that the moving die occurs fatigue damage before the fixed die,and the locations of occuring corrosion pits on the moving and fixed dies are basically aligned with the numerical simulation results of temperature and stress fields,verifiying that the fatigue damage of the die casting dies results from the combined effects of high temperature and high stress.