Effect of Pre-Strain on Low Cycle Fatigue Behavior of Aluminium 7075 T6 Alloy

Abstract

Aluminium and its alloys are now-a-days finding enormous applications in aerospace, automobile and marine sectors where chances of fatigue damage are immense. The objective of the current work is to study effect of pre-strain on low cycle fatigue behavior of 7075 aluminium alloy at ambient temperature.Thermal treatment for producing T6 temper was done on as-received aluminum alloy rods.Attempts were made to study the natural aging response of the alloy with time. Microstructural features of both solutionized and T6 treated samples were compared. Low cycle fatigue behavior of the alloy was studied under three different conditions of pre strain and strain amplitude up to 500 cycles. Results from the low cycle fatigue testing for samples with different combinations of pre strain and strain amplitude showed that for a constant prestrain level, the peak stress first increases and then decreases with increasing the strain amplitude indicating cyclic hardening and/or softening behavior of the alloy. Also for a constant strain amplitude, the strength of the alloy increased as the pre strain level increases.