| AVS 62nd International Symposium & Exhibition | |
| Tribology Focus Topic | Thursday Sessions |
| Session TR-ThP |
| Session: | Tribology Poster Session |
| Presenter: | Jun Tamura, Meijo University, Japan |
| Authors: | J. Tamura, Meijo University, Japan P. Abraha, Meijo University, Japan |
| Correspondent: | Click to Email |
Stainless steels have very good corrosion resistance but the lower surface hardness poses marked limitation on the range of tribological applications that can be envisaged. Here plasma nitriding treatment was performed to improve the hardness without altering the corrosion resistance of austenitic AISI 304 stainless steels.
In nitriding the AISI 304 stainless steel, the passive Cr2O3 layer that protects the surface from corrosion is removed first as it hinders the diffusion of nitrogen species into the bulk of the stainless steel material. The removal of the passive layer was done by argon sputtering and the subsequent nitriding was performed in electron beam excited plasma apparatus under nitrogen and hydrogen atmosphere. The sample temperature was controlled at 400, 450, and 500 degree centigrade. Treated and untreated samples were characterized by means of morphological analysis, Vickers hardness measurements, optical microscope, and x-ray diffractometry.
The results of our experiments show that in neutral nitriding of stainless steel under low temperature, 400 degrees centigrade, the surface hardness increased to 780 Hv, more than two times, that of the untreated surface. Moreover, the cross sectional images show clear nitrogen expanded austenite layer without the formation of compound layer. Measurements of surface roughness and conditions of the surfaces were reasonably maintained. The above results indicate that stainless steels can be used as sliding or meshing mechanical parts in environments such as vacuum chambers and underwater machinery.