Experimental investigation of thixoforging parameters effects on the microstructure and mechanical properties of the helical gearbox cap

The purpose of this work is to discuss the microstructures and mechanical properties of thixoforged helical gearbox caps. The mechanical properties of semi-solid components can be improved by controlling the process parameters such as solid fraction of alloy, die temperature, applied pressure, punch velocity, and heat treatment conditions. In this paper, the effects of forming parameters on the microstructures and mechanical properties of thixoforged A356 helical gearbox caps with an arbitrary shape are studied. The mechanical characteristics were investigated by changing the applied pressure, die temperature, specimen temperature and holding time. The results showed that by increasing the applied pressure from 100 MPa to 150 MPa, the average grain diameter was decreased about 7% and the shape factor was increased about 11%. Also, by increasing the die temperature, the hardness and forming load were decreased about 13% and 21%, respectively. The results illustrated that by increasing the specimen temperature and holding time, there would be an increase in the grain size of primary alpha-Al phase, so the hardness of the specimens is decreased.