Microstructure and Mechanical Properties of AZ61Mg Alloy Fabricated by Multi-Directional Forging Using Die under Decreasing Temperature Conditions / 金型を用いた降温多軸鍛造 AZ61Mg 合金の組織と機械的性質
- Resource Type
- Journal Article
- Authors
- Hiromi Miura; Kota Matsumoto; Masakazu Kobayashi; 三浦 博己; 小林 正和; 松本 洸太
- Source
- 日本金属学会誌 / Journal of the Japan Institute of Metals and Materials. 2015, 79(6):295
- Subject
- dynamic recrystallization
magnesium alloy
mechanical property
multi-directional forging
ultrafine grain
- Language
- Japanese
- ISSN
- 0021-4876
1880-6880
A hot extruded AZ61Mg alloy was multi-directionally forged (MDFed) under decreasing temperature conditions using a die. MDFing was successfully carried out, and the coarse initial grains with an average grain size of 21.6 μm were gradually fragmented to 0.3 μm in average at cumulative strain of ∑Δε=7.2. It showed quite high hardness of 958 MPa and tensile strength of 465 MPa with ductility of 15%. The tensile behavior of the ultrafine grained AZ61 Mg alloy exhibited large temperature and strain rate dependency irrespective of temperature. Superplasticity of 680% elongation to fracture could be achieved at 423 K and at strain rate of 1.0×10−4 s−1. Such mechanical properties depending on temperature and strain rate were reasonably understood by considering the effect of grain boundary sliding. The tensile strength of the MDFed AZ61Mg alloy was further raised to 490 MPa by additional cold rolling.