铸锻复合成形AZ91D摩托车发动机壳体热处理工艺研究

采用不同固溶和时效热处理工艺对液态铸锻双控成形AZ91D摩托车发动机壳体进行了热处理实验。结果表明：样品经过T4（415℃x9h，60℃水淬）处理后，合金的抗拉强度和延伸率最大，其值分别为239．7MPa，1．58％，较未热处理提高幅度分别为41．6％，79．9％。经T6（415℃×9h，60℃水淬＋205℃×16h，空冷）处理后，样品显微组织中的第二相得到均化，在一定程度上强化了合金。未处理态、T4、T6状态下的拉伸试样断口形貌中均存在较多的韧窝，表明铸锻双控成形制件的塑性较好。T6（415℃×9h，60℃水淬）热处理后的拉伸试样断口形貌中韧窝最多，塑性最好。

Research on Heat Treatment of AZ91D Motorcycle Engine Shell Produced by Compound Forming of Die-casting and Forging

Microstructures and mechanical properties of an AZ91D magnesium alloy motorcycle engine shell prepared with compound forming （die casting plus forging） were characterized in various heat treatment conditions. Results show that the ultimate tensile strength and elongation of test samples are up to 239.7MPa,1.58% after solution processing （415℃×9h,60℃ water-quenching）,which have been improved 41.6% and 79.9%, compared with no heat processing. And the microstructures of test samples are uniformed after solution and age treatment （415℃×9h,60℃ water-quenching＋205℃×16h,dry quenching） and the alloy is strengthened to a certain extent. Lots of dimples have been found in the fracture morphology of tensile specimens at no heat treatment,T4 and T6 state, which shows that the parts which are produced by compound forming of die-casting and forging have relatively high plasticity. The fracture morphology of tensile specimen after T6 （415℃×9h,60℃ water quenching） heat treatment have the largest number of dimples,and shows the best plasticity.