| Abstract Scope |
Hyper Duplex Stainless Steels (HDSS) offer superior corrosion resistance and mechanical performance. Characterized by high Pitting Resistance Equivalent Number (PREN ≥ 45), HDSS benefits from elevated chromium and nitrogen, ensuring enhanced resistance to localized corrosion and high yield strengths above 700 MPa, important for seawater exposure and petrochemical systems. HDSS welding fillers maintain a balanced ferritic-austenitic microstructure during complex thermal cycles, minimizing formation of detrimental intermetallic phases like sigma. Compared to super duplex stainless steels, HDSS filler metals improve the corrosion resistance of weld roots and caps and maintain mechanical integrity without increasing susceptibility to 475°C-embrittlement. Experimental studies confirm HDSS weld overlays and claddings show similar phase transformation kinetics to SDSS but with significantly higher corrosion resistance, especially under critical pitting conditions. These attributes position HDSS as a sustainable and high-performance choice for advanced structural applications, offering a viable alternative to more expensive nickel-based alloys in corrosive and high-pressure environments. |