Microstructure and Wear Resistance of Spray-Formed Supermartensitic Stainless Steel

Since the early 90's the oil industry has been encouraging the development of corrosion and wear resistant alloys for onshore and offshore pipeline applications. In this context supermartensitic stainless steel was introduced to replace the more expensive duplex stainless steel for tubing applications. Despite the outstanding corrosion resistance of stainless steels, their wear resistance is of concern. Some authors reported obtaining material processed by spray forming, such as ferritic stainless steel, superduplex stainless steel modified with boron, and iron-based amorphous alloys, which presented high wear resistance while maintaining the corrosion performance(1,2). The addition of boron to iron-based alloys promotes the formation of hard boride particles (M2B type) which improve their wear resistances(3-9). This work aimed to study the microstructure and wear resistance of supermartensitic stainless steel modified with 0.3 wt. (%) and 0.7 wt. (%) processed by spray forming (SF-SMSS 0.3% B and SF-SMSS 0.7% B, respectively). These boron contents were selected in order to improve the wear resistance of supermartensitic stainless steel through the formation of uniformly distributed borides maintaining the characteristics of the corrosion resistant matrix. SF-SMSS 0.7% B presents an abrasive wear resistance considerably higher than spray-formed supermartensitic stainless steel without boron addition (SF-SMSS).