ABSTRACT
For many years the basic materials for construction of hydraulic turbines have been various grades of carbon steels for castings, and structural steels for welded parts. With the increasing growth of machine size and operating head, materials of greater strength have been developed for the fabricated parts of turbines, such as certain grades of low-alloy structural steels that have high strength and good weldability. With the increase of flow velocity through the machines, cavitation erosion becomes a dominating source of damage to turbines. It has become the major concern for many turbine designers and power plant operators. The common metallic material to resist cavitation erosion is stainless steel of various grades which are either used as protective overlays of the carbon steel parts, or to make castings for runner blades, guide vanes or complete runners, and in certain instances, the stay ring and spiral case as well.
