【摘要】 抑制压铸模疲劳损伤是压铸工艺设计的难点之一。首先，对用于压铸型的H13模具钢进行了20～800℃范围的等温拉伸试验，确定了不同温度的屈服强度和塑性模量，并根据试样断口形貌确定了不同温度时的断裂方式；其次，基于有限元方法对镁合金AZ91D平板件压铸过程中铸件和铸型热应力场变化进行了数值模拟。计算结果表明，动模成形区域的最高温度比定模高约44.0℃；动模最大接触应力比定模高约170.7 MPa；动模最大剪切应力比定模高约15.1 MPa。这些结果意味着动模发生疲劳损伤的概率要高于定模。压铸试验表明，动模先于定模发生疲劳损伤；动模和定模出现腐蚀坑的位置，与温度场和应力场数值模拟结果基本一致，验证了压铸模疲劳损伤是高温和高应力共同作用的结果。更多还原

【Abstract】 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.更多还原