軸受鋼の疲労に及ぼす非金属介在物の方向と形状の影響

概要

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The fatigue lives of thin bearing steel plate samples taken in three different directions to the rolling direction were compared by a new-developed bending fatigue testing machine. Observations utilizing SEM-EPMA revealed that fatigue cracks were initiated at the nonmetallic inclusions of the bearing steel. The results obtained are summarized as follows : (1) The inclusions in the vicinity of the surface acted as an initiating point of fatigue fracture in each sample judging from the observation of the directionality of equiaxed dimples. (2) The inclusions giving rise to fatigue fracture were identified for each direction. Namely, fatigue cracks in longitudinal specimens developed at square-shaped Al_2O_3-C_aO or TiN inclusions, those in transverse specimens at linear MnS inclusions, and those in oblique specimens at complex TiN-MnS, Al_2O_3-TiN or MnS inclusions. (3) Oxide inclusions about 5 μm in length can be the initiating point of fatigue fracture depending upon loading directions.
公益社団法人精密工学会の論文
1983-10-05