Investigation about the possibility of hexagonal boron nitride formation to superduplex stainless in order to reduce friction coefficient

Abstract

Manufacturing of many materials, fuels production, energy generation and huge significance on the country's economy are just a few examples that highlight the oil relevance in today's society. In respect of the exploration for this product some challenges are found, mainly related to the critical conditions that the equipments are susceptible on the sea environment. Some examples for this fact are associated with pipes that are used in drilling and oil exploration, called risers. These pipes are generally made of hot rolled stainless steels and have high corrosion resistance, but insufficient wear resistance in some situations. Our research group in Materials Engineering Department at Federal University of São Carlos (UFSCar), in partnership with Petrobras, has been developing many researches about this subject and achieving important outcomes. In a recent project it was possible to verify a positive influence on the wear resistance promoted by hard particles (boride) in stainless steels modified with boron adition prepared by spray forming and coating techniques. Another research project developed by our group aimed at investigating the possibility of hexagonal boron nitride formation (an excelent lubrificant material) to the steel microstructure in order to reduce the friction coefficient. Although this formation was not manifested, the study was able to indicate a favorable thermodynamics to the possibility of the precipitate appearing, which infers that may be necessary some adjustments in the processes parameters. On this context, this project aims at keeping the studies in partnership with Petrobras and investigate the possibility of hexagonal boron nitride formation to superduplex stainless steels. Through this formation, it is hoped that the friction coefficient reduces, resulting in a decrease on the damages caused by contact between the components involved in the oil exploration process. It will be used a superduplex stainless steel which will be manufactured by spray forming in the presence of nitrogen bubbling. Furthermore, it will be added hexagonal boron nitride powder to the melted metal. Finally, the corrosion resistance, friction coefficient and mechanical properties of the developed material will be evaluated. (AU)