INFLUENCE OF THE SOLUTION TREATMENT TEMPERATURE UPON THE CAVITATION EROSION RESISTANCE FOR 17-4PH STAINLESS STEEL

Cavitation erosion is a key factor for extending the running life of hydraulic turbines blades or even runners. Our researches are directed towards new stainless steels composition with reduced carbon content but high cavitation erosion resistance and simultaneously good welding abilities and mechanical resistance. Various steels, with constant Ni content and variable Cr content (alpha gene element) present modifications of the nature and proportions of the constitutive structural components (Austenite, Martensite and Fe-delta) with important consequences upon the cavitation erosion resistance and the value of mechanical characteristics. The cavitation erosion tests were done on a vibratory facility with piezoceramic crystals, realized in agreement with the specifications of the ASTM G32-2010 Standards. The obtained results show that a Cr content of about 6 % give the longest incubation period and the best cavitation erosion resistance, both values being better that those obtained with the steel OH12NDL used in the past, in Romania, on a large scale, for turbine components subjected to cavitation erosion.