Heat-resistant austenitic steels as matrix materials for wear applications above 400°C

• Applicant: Professor Dr.-Ing. Werner Theisen
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 319959745

The mechanisms and factors of high-temperature abrasive wear differ from those of ambient temperature wear. Required high-temperature properties of metals are high-temperature strength and hot-hardness, plastic deformability and hardening ability. These requirements apply, in the field of multiphase materials, primarily to the metal-matrix. The stability of a materials high-temperature wear behavior is mainly determined by the matrix properties. The wear resistance of the metal-matrix itself, as well as the support and integration of hard phases by the metal-matrix are relevant. Austenitic steels are possible Fe-based matrix-materials with increased resistance to high-temperature wear. Especially austenitic steels with a low stacking fault energy (SFE) and a low temperature-dependent increase of the SFE are advantageous for high-temperature abrasive wear applications. The ambition of this research project is to extend the consideration of high-temperature wear of FeCrNi-base alloys to the role of interstitial alloying elements, precipitates, and tribologically induced phase transformations. The interstitial elements C and N have a significant impact on the mechanical properties of austenitic steels. By producing and examining different single-phase FeCrNi(C)N-alloys, the influence of C and N on the metal physical and tribological properties at elevated temperatures should be investigated. In addition, concepts for the precipitation hardening of austenitic steels should be elaborated, to further increase the high-temperature wear resistance. Dispersed precipitates can hinder dislocation movement by acting as obstacles for dislocation slip and thereby contribute to the strengthening of the material. To prove the effect of precipitation hardening on the wear behavior, FeCrNi(C)N-base alloys that allow the precipitation of carbides, nitrides as well as carbonitrides, will be developed. High-temperature wear tests should then elucidate the influence of precipitation hardening on the high-temperature abrasive wear resistance, as well as on the occurring wear mechanisms. Furthermore, deformation-induced phase transformations of the austenitic lattice in the tribologically affected zone, are taken into account. Thereby it should be investigated under what conditions phase transformations occur during abrasive wear and how phase transformations influence the wear behavior.The overarching aim of the project is to gain fundamental understanding of the role of interstitial alloying elements and secondary phases on the tibological behavior in the system of FeCrNi-base alloys and to develop an alloy concept that is customized for high-temperature abrasive wear.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr.-Ing. Sebastian Weber
• Cooperation Partner: Professor Dr.-Ing. Gunther Eggeler