120. Surface Modifications of Hydro-Turbine Components by Laser Treatment – An Emerging Technology

Hydro turbines are likely to have the problem of cavitation and jet erosion in addition to silt erosion. The problem of silt erosion has been tackled with tungsten carbide based hard coatings using HVOF technique. However, the problem of cavitation and jet erosion still needs to be addressed. This problem in hydro turbines can be minimized by treating the erosion prone areas by laser. The technique of Laser treatment allows good hardenability of local well defined areas of various ferrous alloys. With the development of new diode lasers, which have good absorption characteristics and hence better efficiencies, there is potential for wide scale application for hydro components. These lasers are very compact, require low maintenance and are very rugged. BHEL has carried out several studies on laser treated Stainless steel using highly accelerated jet and silt erosion test rigs. Some of the results of our findings and BHEL's future approach to overcome this problem have been highlighted in this paper.