Mechanical Hardening and Resistance to Cavitation Erosion of the Austenitic Stainless Steels with Varying Proportions of Delta Ferrite

Abstract

The paper analyzes, comparative, the resistance to the cavitation erosion for the X5CrNi18-10 classic steel, with that provided by two another steels, processed experimental, with approx. 0.1 % C, 24% Cr, 18 % , approx. 10% Ni and wich was mechanically hardened by vibro rolling. Cavitation tests were performed on a vibrating device with piezoelectric crystal, in the Laboratory of Hydraulic Machines in Timisoara ( LMHT ), determining the characteristic curves of the variation in time of the mean depth erosion, MDE (t ) and mean depth erosion rate, MDER (t). By mechanical tests and by metallographic investigation is warranted increased erosion resistance after cold plastic deformation and minimization the effect of reduction its to higher proportions of delta ferrite , due to higher chromium content. Conclusions detached, after the investigations, serve designers and processors by stainless steel to chemical composition optimization and to manufacturing processes, in order to increase the lifetime of hydromechanical equipment, such as hydraulic turbines, pumps and throttle butterfly valves on pipelines forced, etc.Keywords: mechanical hardening, characteristic curves, resistance to cavitation, microstructure, chemical elements, mechanical properties