Residues Specimen Ecap Force Field Simulation Of Bulk Ultrafine-grained Materials Preparation Industry Research

The method of equal channel angular pressing (ECAP) is one of the methods of severe plastic defromation, which is used to prepare bulk ultrafine-grained materials. The principle of ECAP can be described as, the obtainment of ultrafine grain is attributed to the pure shear caused by severe plastic deformation when the sample is pressd through equal channel crossing certain angles. The ECAPed materials possess a good performance and improvement in strength, hardness, superplasticity and fatigue properties. For the method of ECAP can be carried out on room or elevated temperature without sophisticated equipment, which is potential to be applicated in industrial production, and the ECAPed samples are able to avoid cavity and impurity, this method has attract attentions over the world. The research in this paper focuses several problems with only a little or without others' study, and the contents and results are showing as following:First, the FEM software Deforem 3D is adopted in this paper to study the ECAP process with the influence of retained sample. Compared to the condition without retained sample, the retained sample causes a great increment in pressing load, the effective stress distribution in following ECAPed sample shows uniform in shearing area but at the end of the sample there is a increment both in the value and the gradient; the value of effective strain also increases especially at the end of the sample and the contact face with lower surface of exit channel. The retained sample plays a role of back plunger, which improves the filling in the channel and causes a change in the shape at the end of the sample. The FEM results also show that the end-effection in ECAP process still exists. According to the analysis of the effective stress distribution in ECAP bottom die, H13 die steel is able to be used to preparing ECAP bottom die.Second, a set of ECAP die (Die (A)) have been designed and manufactured. Die (A) is designed with a inner angle Φ=90° , out angle Ψ =30° , and proved by a long term experiment to be proper in structure and stable in application. Third, 2A12 alloy samples has been ECAPed in Die (A), the pressing experiments...