DRF加工されたマグネシウム合金の疲労特性評価

抄録

A new method for strengthening of magnesium (Mg) alloys, Deformation Restricted Forging (DRF) processing, has been invented by Miura et al. High tensile strength over 400 MPa can be attained without any rare earth additions nor special heat treatments. However, the fatigue characteristics of Mg alloys fabricated by DRF processing have not been investigated. For this purpose, rotating bending fatigue tests, static tensile and compression tests were carried out using two types of Mg alloys, i.e., commercial AZ80Mg and DRF-AZ80Mg alloys. As a result, tensile strength and compressive proof strength of DRF-Mg were improved by 80 MPa and 85 MPa respectively compared to those of commercial AZ80Mg alloy. Fatigue characteristics were, however, hardly improved. Generally, in steel materials, it is believed that there is a close correlation between fatigue limit and static strength, where fatigue limit increases with increasing static strength. The relationship between static strength and fatigue strength of the commercial AZ80Mg was proportional and followed the equations statistically of σ_w =0.87σ_0.2c. obtained from the past researches. The characteristics of DRF-Mg alloy, however, did not. Accordingly, fatigue characteristics of DRF-Mg alloy has been found to exhibit entirely different from conventional commercial AZ type Mg alloys.