Research On The Properties And Microstructure Of Rheo-diecasting Al-si Alloy Based On Ultrasonic Preparing Slurry

Due to a lot of defects such as gas porosity and inclusions in the traditional die castings, the die castings don't adapt to be heat-treated to improve their mechanical properties. At present, these problem would be solved effectively through the combination of the semi-solid forming technology with die casting technology.In this paper, it was investigated that the rheo-diecasting process of Al-Si alloy based on ultrasonic wave vibratian preparing slurry. It was found that the alloy properties was enhancd and the microstructure was well improved, and the disadvantage which the traditional die castings can't be heat-treated has been overcomed. So a new way was put forward for the combination of the semi-solid forming technology with die casting technology.The microstructure and properties of the semi-solid rheo-diecasting hypereutectic Al-Si alloy was studied. The results showed that when injection specific pressure was 60MPa and 80MPa and shot speed was medium-speed, compared with traditional die castings, the tensile strength of the semi-solid die castings was raised by 4.5% and 3.0%, and the elongation of that was increased by 63% and 10%. After T6 heat treatment the tensile strength of the semi-solid samples was improved by 36% and 35%, and the elongation of that was enhanced by 32% and 65%. In addition, For the sample after T6 heat treatment,the tensile strength was significantly influenced by pouring temperature,and the elongation was most affected by shot speed. The analysis results of metallographic structure showed that the dendrite of pre-eutectic Si were broken up by ultrasonic wave vibratian and became round.In this paper, the microstructure and properties of the semi-solid rheo-diecasting ZL101 alloy was discussed. It was found that compared with the traditional die castings, the tensile strength of the semi-solid die castings was raised by 4%,and the elongation was enhanced to 300%. Injection specific pressure was the most influence on the tensile strength, and pouring temperature was the least influence on the tensile. Pouring temperature had the most important effect on the elongation, and shot speed had the seldom effect on the elongation. The analysis results of metallographic structure showed that a-Al grain was more round and the dendrite was observed rarely in the microstructure of the semi-solid rheo-diecastings. Moreover, the crystal size of the sample cross-section weren't too greatly gap.