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Additive technologies have been gaining popularity in recent years. Direct metal laser sintering (DMLS), a powder bed fusion method, allows for the easy production of objects of nearly any shape with high precision. DMLS is an advanced material manufacturing method in which a laser scans a powder bed filled with metal powder. This type of steel is often employed where high mechanical strength, hardness, and good corrosion resistance are required. Favorable mechanical properties can be achieved after shot peening (SP), a process often adopted for conventional 17-4PH steel. The aim of the study is to assess the effect of shot peening at different pressures (0.3 MPa, 0.4 MPa) on cavitation erosion resistance and corrosion resistance. Hardness, roughness, XRD phase composition, SEM-EDS analysis, cavitation erosion resistance tests on a vibrating sonotrode test stand and accelerated electrochemical corrosion tests were performed. SP contributed to an increase in hardness from 40.7 % to 52.3 % from 312 HV 0.2 to 439–475 HV 0.2 . The reductions range from 6.7 % to 14 % in Ra roughness compared to the reference material. Dislocation density, along with grain size, were the main factors influencing corrosion resistance. The use of SP with glass beads contributed to an increase in the corrosion resistance of 17-4PH DMLS steel. It was observed that SP caused both the formation of martensite (α) and the reduction of residual austenite (γ). Resistance to cavitation erosion after the shot peening process depended on the exposure time. In the initial phase, it was lower for the material after SP compared to the reference material, but after approximately 4 h, the wear rate increased. As a result, SP ultimately contributed to an increase in cavitation erosion resistance at longer exposure times.
Świetlicki et al. (Tue,) studied this question.