Predicting the Load-Carrying Capacity and Wear Resistance of Duplex-Coated Low-Strength Alloys for Severe Service Ball Valves

摘要

The load-carrying capacity and wear resistance of a duplex-coated 316 stainless steel were determined, and a finite element numerical approach was developed to predict and corroborate experimental observations. Low-strength alloys are generally used for highly demanding valve applications due to their superior chemical stability, galvanic corrosion resistance, and lower susceptibility to stress corrosion cracking failure. Hardfacing (using thermal spraying, laser cladding, or plasma transferred arc welding) is currently the most common solution to protect valve components. Hardfacing provides a thick, hardened case that significantly improves tribological performance. However, hardfaced layers provide lower wear resistance compared to vacuum-deposited hard coatings. One solution to further improve hardfacing performance is a duplex approach, which combines the two processes. This study investigates the following materials: a 316 stainless steel base hardfaced with laser-cladded Co-Cr superalloy and topped with a CVD nanostructured W-WC coating. Tribological properties of three configurations were assessed for their ability to delay initiation of plastic deformation and surface cracking under quasistatic loading and for their resistance to dry reciprocal sliding wear. The results demonstrate that finite element modeling allows numerical prediction and comparison of the load-carrying capacity and wear resistance of duplex-coated AISI 316 stainless steel.