A new approach to sintering and boriding of steels "Boro-sintering": Formation, microstructure and wear behaviors

Abstract

In this study, sintering and boriding methods are applied as a single step, and it is aimed to gain time and economic advantage. For this purpose, powder mixtures prepared in suitable compositions were subjected to sintering and boro-sintering processes. In the boro-sintering process, the sintering was carried out in the boriding atmosphere and the two processes were carried out together. The processing, microstructure, hardness and dry sliding wear behavior of the samples were studied. The powders were pressed under different pressures, and their effects on the properties of the final component were investigated. The sintering process was carried out for 2 h at 1000 degrees C, and the boro-sintering process was carried out at 1000 degrees C for 2, 4 and 6 h. Fe2B and Fe2B + FeB boride phases occurred depending on the boro-sintering process duration. Boride layer thickness varied between 120 and 400 mu m according to boro-sintering duration and cold press pressure. Vickers micro-hardness and Ball-on-disc wear tests were performed on the samples. Whereas 205-215 HV hardnesses were obtained in the sintered samples, 1252-1705 HV hardness values were reached by boro-sintering process. Increased cold pressing pressure reduced wear losses. However, the long boro-sintering time increased surface hardness, but reduced wear resistance.