The influence of thermomechanical processing on the corrosion behaviour and hardness of P91 and 304 stainless steel bimetallic component

ABSTRACT The complex demands on contemporary engineering components have led to the development of advanced materials, such as functionally graded materials. A functionally graded material, P91 and 304 stainless steels (SS), were developed by WAAM and afterwards, post-processing method of thermomechanical processing is adopted. The primary objective of this approach is to enhance interfacial bonding and microstructural control between distinct base metals. The thermomechanical processing encompassed isothermal compression testing at varying deformation temperatures (800, 900, and 1000°C) and strain rates (1 and 10 s–1). The corrosion performance of the as-built bimetallic component was compared with that of the base metals, P91 and 304 SS, by evaluating their electrochemical behaviour in a 3.5 wt% NaCl solution. Hardness results after deformation confirmed microstructural refinement, as evidenced by increasing hardness due to thermomechanical processing parameters. The corrosion results indicated that the thermomechanical processing parameters improved corrosion resistance due to the refined microstructure in the bimetallic component. Uniform corrosion dominated in the as-built condition of the bimetallic component, while pitting corrosion dominated under deformation conditions.