Study On Low Cycle Fatigue Properties Of A4 Aluminum Alloy Forging In Corrosive Environments

In recent years, aircraft structures damages were led to by environments has attracted more attentions of aviation field. Especially the aircrafts service in coastal areas have been corruptted seriously because of environment influence. Therefore, it is very necessary to study low-cycle-fatigue (LCF) behaviors of materials in corrosive environment. It has far-reaching significance for architectural lasting long designs. The data of LCF properties of materials in corrosive environment is scarce at present in civil. This is because the mediums are corrosive, which has great requests for test equipments, test specimens, the experimental environment and testers. It is big difficulty to carry out the experiment. Only very few people succeed in it. My subject has succeed to present LCF experimental study in corrosive environment of A4 aluminium alloy forging. It is not only provides reference for the LCF life forecast of this kind of material in corrosion environment, but also provides an entire feasible LCF test technology of materials in corrosive environment for material test field. Thus the technology will make a big step from China to internet.The thesis has studied LCF properties of A4 aluminium alloy forging in four kinds environments which they are laboratory air, moist air (RH≥90％), 3.5％NaCl salt fog, 3.5％NaCl salt fog + SO2, respectively. The comparisons of strain versus life curve and circulation stress versus strain curve were made of A4 aluminium alloys forging in four kinds environments. Analyzed LCF specimens fractures of A4 aluminium alloy forging in air environment and corrosion environment. Adopt the most common used method to fit the LCF parameters, and draw cyclic stress versus strain curve and LCF curve of A4 aluminium alloys forging in four environments. Test result is indicated: Under identical strain, the LCF life in air is longer than that in moist air; The LCF life in moist air is all longer than that in 3.5％NaCl salt fog and in 3.5％NaCl salt fog + SO2; The LCF life in 3.5％NaCl salt fog approaches basically 3.5％NaCl salt fog + SO2.