Fatigue Strength of Aluminum 2024 after Sub Zero Treatment

Challenge of change of alloy properties during service life of extra safety parts was always considered by industrialists and consequently researchers. Fuselage and wings of airplane repeatedly in ascent and descent is affected respectively by cooling to -55 0C and heating to environment temperature. Hence, the effect of above temperature changes on tensile and fatigue properties is unknown. In this study in laboratory, the situation of airplane body working is simulated and then the changes of microstructure and consequently the changes of tensile properties and hardness after holding for 10 and 4 hours were studied respectively in temperature -60 and -196 0C. Results showed that by using of sub-zero treatment, hardness is without change but tensile properties are increased to control sample and when the cooling rate was low (less than 1 degree per minute), more improvement will be achieved in tensile properties. While results showed that by using of sub-zero treatment, fatigue strength is decreased at least 20% to control sample