Affiliation:
1. Department of Mechanical and Mechatronics Engineering, Faculty of Engineering,Built Environment and Information Technology, Central University of Technology, Free State Private Bag X20539, Bloemfontein, South Africa
2. Department of Mechanical Engineering, School of Engineering and Technology, South Eastern University Kenya, Kitui, Kenya
Abstract
Heat treatment of direct metal laser sintering (DMLS) Ti6Al4V (ELI) generates different mechanical properties of the alloy depending on the heat treatment cycle adopted. This is due to the different aspects of the microstructure, such as phase fraction, grain size, texture, and dislocation density, which vary with heat treatment. Other external factors, such as the prevailing level of strain, strain rate, and temperature, also affect the mechanical properties of the material. This paper presents the development of a theoretical model that couples the effects of strain rate, temperature, strain, grain size, and initial dislocation density to describe the flow properties of DMLS Ti6Al4V (ELI). According to the model, higher initial dislocation density results in higher yield stress, low strain hardening, and earlier saturation of flow stress. The model shows that the parabolic shape of the stress-strain curve of the alloy is dictated by the initial dislocation density, which is generally a factor of grain size.
Funder
Council for Scientific and Industrial Research, South Africa
Subject
General Engineering,General Materials Science