Research On The Semi-solid Thixo-extrusion Of 6063 Alloy And Numerical Simulation

At the beginning of 20th century 70's, America Massachusetts Institute of Technology Researcher D.S.Spencer and other Researcher find metal special dynamical performance during solidification. Afterwards, under direction of professor Flemings, formed mechanism of semi-solid alloy with spheric primary phase, dynamical performance of semi-solid slurry and its formed characteristic were deep researched, found concept,theory and technique of semi-solid formation. Along with semi-solid forming technique come mature day by day, cost decline remarkably, product quality improve constantly, so called new generation metal forming technique of 21st century by experts.This paper based on 6063 alloy, manufacture of semi-solid ingot,reheating,thixo-extrusion, in addition, the process of semi-solid thixo-extrusion and tradition extrusion of 6063 aluminum alloy were numerically simulated. The following results were obtained from above work:The structure of 6063 slurry by near-liquidus casting technology is even and small.The reheating microstucture evolution is affected by reheating temperature and holding time. The growth and globe rate of a phase were increased with the reheating temperature in solid-liquid phase zone. The best technical parameters of reheating is 630℃at 30 minutes or 640℃at 25 minutes. Under these conditions, its volume fraction of liquid is about 23%, and the average equal-area-circle grain diameter is about 160μm.The power of the extrusion was smaller, but the velocity was bigger in the process of semi-solid thixo-extrusion. The compressive strength is 297 MPa, and the specific elongation is 19.87%. The mechanical properties are much better than normal extrusion's.The 3D finite element simulation software Deform-3D was employed to simulate the process of semi-solid thixo-extrusion and tradition extrusion of 6063 aluminum alloy. The results show:under the same extrusion condition, the force loaded on the die in the process of semi-solid thixo-extrusion was over 10 times smaller, the stability time was shorter, and the fluctuation of effective stress through the steady period was also smaller, compared with the traditional extrusion process. Through this research, the advantage of semi-solid thixo-extrusion was more obvious.