Laser beam welding of commercially pure titanium sheets

Abstract

In the present work, effect of process parameter such as laser power, welding speed, size of beam diameter on the microstructure and mechanical properties on laser beam welding of annealed commercially pure titanium (cp-ti) grade-2 is investigated.Titanium is preferred due to its wide applications in the field of automobile, marine, aerospace, power plant, structural etc. for its light weight, high specific strength, high corrosion resistance, having good mechanical properties at elevated temperature.Laser welding has more advantages over other normal fusion welding due to its low heat input, high cooling rate and high power density.it provides deeper and narrower weld bead results high welding efficiency and smaller heat affected zone leads to good mechanical property.The laser welding of cp-ti sheet of 1mm thickness was carried out by using a continuous wave (CW) CO2 laser at different operating conditions such as laser power at 2kW & 2.5kW, welding speed from 4m/min to 8m/min and laser intensity distribution by Gaussian Mode (0.18mm beam diameter at focus) and Donut Mode (0.36mm beam diameter at focus).Microstructure of weld size and fusion zone were examined by using optical microscope at different magnifications.Weld size was decreased with increasing welding speed and increased with increasing laser power and spot diameter.At low welding speed, elongated grains were observed in the weld interface. It also showed a sharp interface at large beam diameter (Donut mode). Measurement of micro-hardness was taken across the welding by using micro-hardness testing machine. The Vickers hardness increases from base material to centre of weld region. Tensile testing of the weld was carried out in a universal testing machine and it is observed that tensile strength of weld at different process parameters is approximately equal to the tensile strength of base metal.Comparative studies of process parameters on the laser welding of cp-ti were investigated.