| Popis: |
The rolling bearing is one of the key components for the functioning of sophisticated machinery in the demanding industrial world today. For efficient and smooth operation, bearings need to sustain wear, fatigue, high loads, and sometimes, heat and harsh environments. Preceding failure analysis of the current work concluded that the recurring failure of the bearings under consideration is predominantly caused by the excessive wearing of the bearing track, and false brinelling due to harsh corrosive environment. This work, as a remedial measure, aims at enhancing the bearing life by suitably applying nitrocarburizing, a thermochemical heat treatment, to bearing parts. By heat treatment, nitrogen and carbon are diffused in hardened bearing races and rolling elements at a relatively lower temperature of 560-580 °C followed by controlled oxidation. Structural transformation during the process formed a compound layer at the sub-surface consisting of s−Fe2-3(N, C) and y'-Fe4(N, C) phases and a thin continuous layer of Fe3O4 on the compound layer as confirmed by X-Ray diffraction and microstructural analysis. Microhardness profile confirmed progressively declining hardness from the surface towards the core.Salt spray tests performed on the nitrocarburized parts indicated excellent corrosion-resistance properties. |
