The hardness and structure of bearing steel GCr15 by normal continuous spheroidizing annealing at 780 °C with 15 -20 °C/h furnace cooling to 660 °C

and by isothermal spheroidizing annealing at 780 T with 30 °C/h cooling to 720 °C for 2 h then with 20 °C/h furnace cooling to 660 °C are compared and analyzed. Results show that at same annealing time condition

by using continuous annealing process the HB hardness value of steel CCr15 is 184 〜202 and the spheroidizing structure rating is 2. 0 〜3. 5

while by using isothermal spheroidizing annealing process the HB hardness value of steel GCr15 is 191 ~ 198 and the rating of spheroidizing structure is 2.0 ~ 2. 5 to get better effect.