PSI - Issue 71

Ninad Vasant Pawar et al. / Procedia Structural Integrity 71 (2025) 134–141

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Fig. 6 SEM images of three different fracture zones at different magnifications. (a) and (b) show near groove surface zone or zone 1, (c) and (d) in the mid zone or the zone 2, (e) and (f) show zone 3 which is fast fracture zone. Fig 6(g) and (h) show additional images from comparatively undamaged initiation zone showing ratchet-like marks and micro-surface features observed in the initiation zone at 1200x magnification. The direction of ridge marks identifies the fracture progression from groove surface towards cone large face. Cone is made of SAE 52100 surface treated and then quench-tempered to have more carbon and nitrogen on the surface to form a wear-resistant layer consisting of carbides, carbonitrides, and retained austenite. The hardness profile taken from groove surface as well as flange rolling surface, which is the functional surface where roller face is in sliding contact with flange, is given in fig. 8. It is evident that the surface is having more microhardness due to the surface treatment as -