Effect of Laser Surface Melting On Fatigue Life of Aluminum 6061-T6

Abstract

This study is carried out to investigate the effect of laser surface melting on fatigue life of aluminium alloy. Aluminium is widely used in automobiles, marine vessels, aircraft, spacecraft railway cars and bicycles. Under fatigue loading aluminium like magnesium and copper shows a different behaviour as compared to steel and iron i.e. aluminium doesn’t show a distinct fatigue limit. Considering research previously carried out, surface roughness has great impact on fatigue life i.e. higher the roughness less the fatigue life is. This is because crack initiation and propagation is easy on surface with more roughness as compared to less rough surface. In CNC turning operations, machining conditions like feedrate, depth of cut and cutting speed have great impact on surface roughness. In this research work specimens are prepared on CNC turning machine as per ISO 3685 and fatigue testing is done on four-point rotating bending fatigue testing machine as per BS ISO 1143:2010. After the preparation of specimens, roughness of each specimen was measured. Surface of specimens from each combination of machining conditions was then melted using CO2 Laser on 3 different energy densities. Absorption of aluminium was enhanced using carbon black paste. Noticeable reduction in surface roughness and a general trend of increase in fatigue life after surface melting of aluminium is observed.