Since the thixotropic properties of semi-solid metals were discovered by American scholars in the 1970s, semi-solid processing technology has been rapidly developed and applied in industry. However, the semi-solid forming technology and theoretical research are far less perfect and mature than all liquid casting and all solid forging, especially the rheological extrusion casting technology in rheological forming technology, which is still in the early development and continuous improvement stage. Through design development manufacture semi-solid squeeze casting forming equipment, study its Shear with laboratory with independent intellectual products Low temperature casting technology, Low Superheat Pouring with a Shear Field, referred to as LSPSF) smooth connection, research on rheology of squeeze casting technology, analysis the influence law of process parameters on product performance and mechanism, the promotion of rheology of semi-solid squeeze casting technology and its industrial application has the following significance:
(1) Design and manufacture semi-solid extrusion casting molding equipment with independent intellectual property rights. In the current situation of squeeze casting development, the research of squeeze casting equipment is far less than that of die casting machine, which seriously restricts the development and popularization of rheological squeeze casting technology. Through the development of new process and new equipment, the low consumption and energy saving rheological forming technology can be promoted and applied. The combination of the numerical control LSPSF pulping process developed in the laboratory and the vertical 3000kN semi-solid extrusion casting machine lays a good foundation for the subsequent development and industrial application.
(2) The slurry is prepared online for rheological forming. The actual conditions imposed by the two solidification of the alloy melt are more complex and changeable. The microstructure formation mechanism and solidification process of the semi-solid parts solidified under the condition of high pressure and high cooling in rheological squeeze casting are studied. On the one hand, it is to optimize and popularize the basic theory of rheological extrusion casting based on LSPSF technology, on the other hand, it is to deepen the understanding of rheology from the mechanism and essence, which has important practical guiding significance for the analysis and understanding of other new methods and equipment of rheological forming.
(3) Through the connection between vertical indirect squeeze casting forming equipment and LSPSF process, the continuous and integration of semi-solid slurry preparation and forming can be realized, and the accumulation of first-hand test data and process experience can provide basic technical support for promoting semi-solid processing technology to be directly oriented to industrial application.
(4) The rheological extrusionof cast aluminum alloy A356 was experimented and studied, and its microstructure and mechanical properties were analyzed. The rheological indirect squeeze casting experiment and research of aviation high strength aluminum alloy 7075 were carried out. The effects of extrusion casting process parameters and heat treatment process parameters on microstructure and mechanical properties were analyzed. It is of great significance to realize the application of rheological forming technology of aluminum alloy to aviation, automobile, household appliance and other industries.