Conception of tooling adapted to thixoforging of high solid fraction hot-crack-sensitive aluminium alloys  

作　　者：G.VANEETVELD A.RASSILI J.C.PIERRET J.LECOMTE-BECKERS 

机构地区：[1]Thixo Unit,B56,University of Liège [2]Special Metallic Materials,B52,University of Liège

出　　处：《Transactions of Nonferrous Metals Society of China》2010年第9期1712-1718,共7页中国有色金属学报（英文版）

基　　金：University of Liège,Walloon Region (First Europe Program Convention n°"NEP" 415824,THIXALU Project and MAGAL Project) and the COST 541 for their financial support

摘　　要：Thixoforging is a type of semi-solid metal processing at high solid fraction (0.7<φs<1), which involves the processing of alloys in the semi-solid state.Tooling has to be adapted to this particular process to benefit shear thinning and thixotropic behaviour of such semi-solid material.Tooling parameters, such as the forming speed and tool temperature, have to be accurately controlled because of their influence on thermal exchanges between material flow and tool.These thermal exchanges influence the high-cracking tendency and the rheology of the semi-solid material during forming, which affects parts properties and therefore their quality.Extrusion tests show how thermal exchanges influence quality of thixoforged parts made of 7075 aluminium alloys at high solid fraction by modifying process parameters like forming speed, tool temperature and tool thermal protector.Thus an optimum in terms of thermal exchanges has to be found between surface quality and mechanical properties of the part.A direct application is the evaluation of surface quality of thixoforged thin wall parts made of 7075 aluminium alloy.Thixoforging is a type of semi-solid metal processing at high solid fraction （0.7〈φs〈1）, which involves the processing of alloys in the semi-solid state. Tooling has to be adapted to this particular process to benefit shear thinning and thixotropic behaviour of such semi-solid material. Tooling parameters, such as the forming speed and tool temperature, have to be accurately controlled because of their influence on thermal exchanges between material flow and tool. These thermal exchanges influence the high-cracking tendency and the rheology of the semi-solid material during forming, which affects parts properties and therefore their quality. Extrusion tests show how thermal exchanges influence quality of thixoforged parts made of 7075 aluminium alloys at high solid fraction by modifying process parameters like forming speed, tool temperature and tool thermal protector. Thus an optimum in terms of thermal exchanges has to be found between surface quality and mechanical properties of the part. A direct application is the evaluation of surface quality of thixoforged thin wall parts made of 7075 aluminium alloy.

关 键 词：THIXOFORGING solid fraction near-net-shaping TOOLING 7075 aluminium alloys 

分 类 号：TG319[金属学及工艺—金属压力加工]