Carbides formation in weld metal produced by recycling of titanium machining swarf

Abstract

Application of titanium alloys for orthodontic implants have increase in last years and it has generated a great amount of titanium chips which are disposed as metal scrap. Titanium carbide has high hardness and can be applied as coating reinforcement against wear. Chips of titanium alloys were processed and used in the fabrication of experimental hardfacing consumables for improving the resistance of wear of mechanical components. Coatings were produced in cast steel specimens using the gas tungsten arc welding process. Microstructure was investigated by means of scanning electron microscopy. Microhardness of the coatings was analyzed by a dynamic ultra-micro hardness tester. The microstructure of the welding metal was composed of circular particles of titanium carbide surrounded by a ferritic matrix. The measures made by electron dispersive spectroscopy showed a variation in titanium amount trough the weld, where larger contents of titanium were found, and the matrix. The crystallographic analyses reinforced the formation of titanium carbides embedded in a ferrite matrix into welding metal.