Liquid Combination Process Of Die Casting-Forging And Heat Treatment Process Of AZ91D Motorcycle Engine Shell

Liquid combination process of die casting-forging is a new forming method with the advantages of die casting and die forging. Because of rheological filling, the shape of parts can be easily controled by die casting , but the performances of parts can not be easily controled. While the die forging, the performances of parts can be easily controled because of the existence of plastic deformation, but the shape of parts will be limited greatly. Both of the shape and performances of parts can be controled by Liquid combination process of die casting-forging in the same forming.The liquid combination process of die casting-forging consists of die casting filling process and die forging process. Its main processing parameters include the die casting processing parameters and the die forging processing parameters. The products can be formed with revamped common hydraulic press and die casting machine, and the special purpose machine as well.The AZ91D motorcycle engine shell with both good performances and shape has been formed by selecting each processing parameter properly. Compared with die casting motorcycle engine shell, it has competitive properties.The mechanical properties test and microstructure observation of AZ91D motorcycle engine shell fore and after heat processing which been formed through liquid combination process of die casting-forging have been done by Erichsen test , metallographic analysis and scanning. The effects of the microstructure evolution of AZ91D motorcycle engine shell formed by liquid combination process of die casting-forging and the relation between microstructure and mechanical properties in solution process and age treatment were studied. The results show that the mechanical properties of test samples after heat processing optimization are higher than which of the without heat processing specimens. The ultimate tensile strength and elongation were up to 239.7MPa, 1.5763% after solution processing(415℃×9h, water-quenching), which have been improved 41.6% and 79.9%, compared with without heat processing. And the microstructures of AZ91D motorcycle engine shell formed by liquid combination process of die casting-forging were uniformed after solution and age treatment(415℃×9h, Water-quenching +205℃×11h, dry quenching), which strengthened the alloy, to a certain extent. But the properties of the test sample under this state did not reach what we expected, because of the existence of defects. By analysis, it is concluded that AZ91D motorcycle engine shell formed by liquid combination process of die casting-forging can be strengthened after solution and age treatment(415℃×9h, Water-quenching +205℃×11h, dry quenching)to make the performances of parts best. This study provides the foundation on the selection of processing parameters for the heat processing of AZ91D motorcycle engine shell formed by liquid combination process of die casting-forging.