EFFECT OF HEAT TREATMENT ON SLURRY EROSION BEHAVIOUR OF 21-4-N NITRONIC STAINLESS STEEL

Abstract

Energy is one of the key factors that influence the development of a nation providing economic and social benefits to its people. This is more important in developing countries like India, for economic development at micro level necessitating the need for the availability of secure and sustainable energy. In various hydro power plants mainly in the Himalayan region, underwater components encountered with the problem of erosion. The erosion is mainly caused due the presence of silt in the flowing water from the mountains in the Himalayan region. Erosive wear is caused by the impact of abrasive particles against a solid surface. Erosion is rapid and severe forms of wear and can results in significant costs if not adequately controlled. Erosive wear occurs in a wide variety of machineries and typical examples are the damage to gas turbine blades when an aircraft flies through dust clouds, hydro turbine under water parts when silt laden water flows through it and the wear of pump impellers in mineral slurry processing systems. It is seen that hydro power plants suffer a serious setback due to rapid erosion of underwater parts by silt laden water. The factors affecting the erosion rate are general factors and metallurgical factors. The general factors include erodent particle hardness, size, shape, impact angle affect the erosion rate but these factor can't be changed. Only material characteristic/properties like material hardness, microstructure, toughness and strength could be changed to get better erosion resistance. This can be achieved through a heat treatment process. Hardness is the most important characteristic to consider while selecting the materials for minimum erosion rate. Generally wear resistance increases with hardness and decreases as toughness increases. But in the case of erosion, a combination of optimum hardness and toughness increases the erosion resistance.