Advancing Renewable Energy Materials: Corrosion and Strength Optimization of 17-4 PH Stainless Steel for Geothermal Turbines

This research explores the engineering and performance evaluation of 17-4 PH stainless steel as a potential material for geothermal power plant (GPP) turbine blades. As part of efforts to promote renewable energy innovation within industrial engineering, the study focuses on enhancing material reliability through microstructure optimization and property control. The material was manufactured via investment casting at PT SPVMB, followed by four heat treatment variations: H900, H1025, intermediate AVG, and an as-cast condition, aligned with ASTM A747 standards. Mechanical and corrosion characterizations were conducted through hardness and tensile testing, electrochemical corrosion analysis in actual geothermal brine from the Dieng GPP, and microstructural observation using optical microscopy. Among all samples, the H900 condition achieved the highest hardness and yield strength (48.46 HRC and 939.25 MPa) but showed a higher corrosion rate. In contrast, the H1025-treated material displayed balanced mechanical strength (43.88 HRC, 860.91 MPa) and the lowest corrosion rate (0.027 mm/year), supported by a uniform tempered martensitic structure. These results suggest that optimized heat treatment significantly enhances the suitability of 17-4 PH stainless steel for sustainable geothermal applications. The H1025 condition meets all GPP blade requirements (hardness, strength, and corrosion resistance), thus supporting the broader agenda of durable materials innovation for renewable energy systems.