Wave Deformation Hardening of Bimetallic Materials with a Copper Alloy Coating on a Steel Substrate

The use of bimetallic materials composed of copper alloys and steel offers operational and economic advantages. Sintering copper powder onto a steel substrate serves as a relatively simple and effective method for producing such bimetallic materials, with the addition of tin and lead during sintering enhancing anti-friction properties. However, a key limitation of this method is the relatively low hardness of the copper alloy layer. Moreover, lead has a tendency to form large inclusions at the grain boundaries of copper, which can act as stress concentrators and initiate cracks, ultimately leading to material failure. Wave deformation hardening (WDH) has been identified as a strategy to address this issue. WDH has shown to be effective for hardening metallic materials at room temperature and when preheated. In this study, WDH was applied to copper alloy coatings on steel substrates in bimetallic samples heated to various temperatures, with the results showing that WDH significantly increased the hardness of the copper alloy layer. The size of large lead inclusions in the copper alloy microstructure was also reduced, while the number of smaller inclusions increased, resulting in a more uniform distribution. The most favorable results were obtained at a WDH temperature of 300°C, which produced more than a threefold increase in hardening compared to room-temperature treatment. WDH effectively improves the mechanical properties of bimetallic materials.