Synopsis Carbid e segregation In ball· bearing steel has been deemed harmfu l to its life. But unfortunately there is no concrete experimental data on this problem. In order to see the effects of this segregation, a flattening test, which proved the strength at room temperature and a life test, were per· formed. Test pieces were taken from each ingot belonging to the same heats. These ingots were heated at h igh temperatures for different durations. Conseq uently the grades of segregation in

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... h ingot were found to be different. A ring made of the ball·bearing steel was quenched, tempered and flattened between two arms of a physical test machine. Carbide segregation s lightly affected the flattening strength of the ring. But from the practical point of view, these effects could be neglected. A life· test machine was invented by the Government Mechanical Laboratory. A small needle cut from the tube was rolled between three rolls. Its li fe was measured by the noise ca used by flaking on the surface of the needle. Microscopic segregation did not affect the life of ball ·bearing steel.