时效处理对高强韧压铸Al-Mg-Si-Mn合金力学性能的影响

摘要

Al-Mg-Si-Mn alloy can be used to produce high strength automotive components due to its excellent strength and toughness. In order to improve the mechanical properties of die casting Al-Mg-Si-Mn alloy, artificial aging treatment (250℃ ×l h) is adopted in the present work. Tensile and fatigue tests are conducted on as-cast and aged samples. Optical microscope and SEM are used to observe the microstructural variation after aging treatment and analyze the fatigue fracture surface. The results indicate that the amount of β-Al8Mg5 distributed in the matrix decreased obviously after aging treatment. Ultimate tensile strength, yield strength and hardness increased 14%, 29% and 9%, respectively. Elongation slightly changed from 8.31% to 8.47%. In addition, effect of aging treatment on fatigue life is negligible.%压铸Al-Mg-Si-Mn合金强度高、韧性好,在高强韧汽车零部件的制造上拥有良好的应用前景.为进一步提高压铸Al-Mg-Si-Mn合金的力学性能,在本研究中对高强韧压铸AlMg5Si2Mn合金进行了250℃下保温1h的人工时效处理,测试了铸态和人工时效后的拉伸和疲劳特性,观察了时效前后的微观组织变化,并且对疲劳断口进行了分析.试验结果表明:AlMg5Si2Mn合金在时效处理后分布于α-Al基体上的β-Al8Mg5相减少；试样的抗拉强度、屈服强度和硬度分别提高14％、29％、9％,断后伸长率变化不明显；时效处理对合金的疲劳寿命没有明显的影响.