Some Microstructural Aspects on Humidity-Enhanced Deterioration in the Fatigue Strength of Age-Hardened 7075 Al Alloy
Age-hardened 7075 Al alloys are one of the materials which possess large strength and large toughness.Their weight and large resistance to corrosion are also attractive in practical use.We have recently shown that the fatigue behavior of extruded 7075-T6 Al alloy is strongly influenced by the humidity in atmospheric air,and the fatigue strength decreases markedly at the humidity higher than about 60%.In addition,shear-type fracture with high crack growth rate occurs at high humidity,while tensile-type fracture dominates at low humidity.The occurrence of the change in fracture mode,however,depends on the conditions used in fatigue tests.In the present study,microstructures of the 7075 T6 Al alloy subjected to fatigue tests in various conditions and humidity are examined by using electron backscattering diffraction (EBSD) and X-ray diffraction (XRD).The results of EBSD and XRD analyses indicate that the microstructures depend on the history of metalworking and heat treatment and that the fatigue properties in high humidity environment are influenced by the difference of the microstructures in addition to the effect of humidity.A crytallographic geometry model is also shown to interpret the preferential occurrence of the shear-type fracture based upon the EBSD analyses.
Fatigue Humidity Fracture mode 7075-T6 Al alloy Microstructure
Yuzo Nakamura Kohji Kariya Norio Kawagoishi
Department of Mechanical Engineering,Graduate School of Science and Engineering,Kagoshima University Department of Mechanical System Engineering,Daiichi Institute of Technology Kirishima 899-4395,Japan
国际会议
北京
英文
1-10
2013-06-16（万方平台首次上网日期，不代表论文的发表时间）