Experimental and FE simulation studies of superplastic forming of Al 7075 alloy

Abstract

Superplasticity is the ability of a polycrystalline material to exhibit, in a generally isotropic manner though there are some works reported on anisotropic behaviour also, very large elongations without necking prior to failure. Elongations in excess of 400% are usually referred to as superplasticity, although several alloys have exhibited elongations exceeding 1000%. The highest elongations reported are 4850% in a Pb-Sn eutectic alloy, and greater than 5500% for aluminium bronze. Superplasticity in sheet metals offers advantages for forming complex shapes easily in high strength alloys, as a regular production process. The focus of the present work is to arrive at the optimum process parameters in the superplastic forming of 7075 aluminium alloys, so as to achieve minimum thinning, lesser forming time and reduction in micro cavities. This thesis is broadly divided into five parts, viz: (i) Material Selection and grain requirements (ii) Determination of the m value of the specimen material (iii) Superplastic forming under different conditions (iv) Finite element analysis (v) Studies on Post-forming properties The first part is concerned with the introduction, survey of literature, selection of suitable materials, and the grain requirement technique. It consists of chapters 1, 2, and 3. The first chapter deals with an introduction to superplasticity, superplastic alloys and their applications. A brief account of the scope of the present work is also presented in this chapter.