<title>High power CO<formula><inf><roman>2</roman></inf></formula> lasers and their material processing applications at Centre for Advanced Technology, India</title>

Abstract

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.