Semi-Solid Forging Process of Aluminum Alloy Connecting Rods for the Hydrogen Internal Combustion Engine

As an important piece of equipment for hydrogen energy application, the hydrogen internal combustion engine is helpful for the realization of zero carbon emissions, where the aluminum connecting rod is one of the key core components. A semi-solid forging forming process for the 7075 aluminum alloy connecting rod is proposed in this work. The influence of process parameters, such as the forging ratio, sustaining temperature, and duration time, on the microstructures of the semi-solid blank is experimentally investigated. The macroscopic morphology, metallographic structure, and physical properties of the connecting-rod parts are analyzed. Reasonable process parameters for preparing the semi-solid blank are obtained from the experimental results. Under the reasonable parameters, the average grain size is 41.48~42.57 μm, and the average shape factor is 0.80~0.81. The yield strength and tensile strength improvement ratio of the connecting rod produced by the proposed process are 47.07% and 20.89%, respectively.