Effect of tempering temperature on microstructure and mechanical properties of laser additive manufacturing repaired AISI 403 steel

Martensitic stainless steel is widely used in the manufacturing of steam turbine blades, but the blades are prone to damage during long-term operation. As an advanced manufacturing method, additive manufacturing technology has been successfully applied in the field of metal repair. This study employed powder-fed laser additive manufacturing technology to repair AISI 403 steel, investigating the impact of tempering temperature on the mechanical properties of the repaired components. Through microstructural and mechanical property analyses, the optimal tempering temperature was determined to be 750 °C. After tempering at this temperature, the repaired components achieved excellent comprehensive mechanical properties: a yield strength of 555.4 ± 21.7 MPa, an ultimate tensile strength of 775.9 ± 27.8 MPa, and an elongation of 19.5 ± 2.5 %. The results indicate that the strength of the repaired part is higher than that of the base material, while maintaining a certain level of plasticity, providing theoretical basis and technical reference for the repair of steam turbine blades.