The free cutting 22CrMoHS gear steel (/% ：0.19 〜0.25 C

0.80~1.00 Mn

W0.025 P

0. 040 ~0. 060 S

l. 00 〜1.40 Cr

0. 35 -0.45 Mo) is developed by Suzhou Steel Group. The range of sulfur content in steel is 0.040% ~ 0. 060%. With controlling end point carbon of electric furnace 0.05% ~ 0.12%

beginning refining slag basicity R 4 ~ 5 and (Al

2

0

3

) 25% ~35%

end of refining slag basicity R 3 ~4 and ( Al

2

0

3

) 25% ~35% at LF

after VD feeding calcium wire to control the calcium content in steel 0.0015% 〜0.0025%

secondary cooling water 0. 81 1/Kg

and casting speed 0.75 ~0. 80 m/min

the sulfide in the steel is mainly spherical

and the spheroidization ratio of sulfide inclusions is up to 90% to greatly improve the cutting performance of steel.