Abstract
In this report, austenitizing behaviour and rapid life test of drawn wire for bearing ball were studied, and the effects of ingot size's difference, raw materials and vanadium addition were investigated.
The results obtained are summarized as follows;
(1) In quenching and tempered (1h) condition, the hardness increases to 860°C quenching temperature, but above 860°C it decreases.
(2) The bending stress decreases generally with quenching temperature, and between 820°C and 840°C quenching temperature it does not decrease except B steels.
(3) The solution of the carbide into austenite is very rapid to 840°C temperature, but inactive above 840°C temperature.
The austenitizing behaviour of the carbide is very different in C 1 and C 2 on account of vanadium addition.
(4) In A steels the retained austenite increases with quenching temperature, and it does not increase to 840°C quenching temperature in C steels.
(5) In rapid life test of A steels the mean and standard deviation of life times become better and crack damage is improved, if the imported scraps from america are charged more as raw materials.
The mean of it becomes better, but crack damage becomes worse on account of vanadium addition in C Steels.
In commercial B steel the mean of it and crack damage are worst.
