High power CO2 lasers and their material processing applications at Centre for Advanced Technology, India

We have developed high power transverse flow (TF) CW CO2 lasers up to 15kW, a high repetition rate TEA CO2 laser of 500Hz, 500W average power and a RF excited fast axial flow CO2 laser at the Centre for Advanced Technology and have carried out various material processing applications with these lasers. We observed very little variation of discharge voltage with electrode gap in TF CO2 lasers. With optimally modulated laser beam we obtained better results in laser piercing and cutting of titanium and resolidification of 3 16L stainless steel weld-metal for improving intergranular corrosion resistance. We carried out microstructure and phase analysis of laser bent 304 stainless steel sheet and optimum process zones were obtained. We carried out laser cladding of 316L stainless steel and Al-alloy substrates with Mo, WC, and Cr2C3 powder to improve their wear characteristics. We developed a laser rapid manufacturing facility and fabricated components of various geometries with minimum surface roughness of 5-7 microns Ra and surface waviness of 45 microns between overlapped layers using Colmonoy-6, 3 16L stainless steel and Inconel powders. Cutting of thick concrete blocks by repeated laser glazing followed by mechanical scrubbing process and drilling holes on a vertical concrete with laser beam incident at an optimum angle allowing molten material to flow out under gravity were also done. Some of these studies are briefly presented here.