Processing of 17Cr7Mn6Ni TRIP Steel Powder by Extrusion at Room Temperature and Pressureless Sintering

Transformation-induced plasticity (TRIP) steels are known for their outstanding strength and their excellent deformation properties, which are necessary for the improvement of occupant safety elements in air, rail and motor vehicles. One precondition for the realization of the TRIP effect is the creation of a metastable austenitic microstructure through the addition of a number of alloying elements. The great affinity of some alloying elements for oxygen implies the formation of highly stable oxides during thermal processing. In the current study, an extrusion process (derived from the processing of ceramics) with subsequent debinding and pressureless sintering is used to manufacture compact strands from prealloyed and gas-atomized 17Cr7Mn6Ni TRIP steel powder. The influence of both the debinding temperature and sintering atmosphere on the oxide particle content in the final bulk product are investigated by X-ray diffraction (XRD) analysis and quantitative metallography. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis in association with temperature-programmed reduction (TPR) experiments, thermogravimetric (TG) measurements and mass/infrared spectroscopy (MS/IRS) serve to monitor the changes in the steel powder surface composition and the effectiveness of hydrogen as a reducing agent.