The cutting characteristics of common gear steel 20CrMnTiH (0. 006% S) and sulphur bearing gear steel 20CrMnTi (0. 031 % S) with different cutting speed (200 ~230 m/min) and cutting depth (0. 5 ~2 mm) have been tested and researched. Results show that with increasing cutting rate

the wear of tool increases

with cutting speed 200 m/min the service life of 0. 031% S steel is 2. 8 fold as long as that of 0. 006% S steel and with cutting speed 230 m/min the service life of 0. 031 % S steel is 2. 6 fold as long as that of 0. 006% S steel ； with increasing cutting depth the cutting force increases

but with definite cutting depth the cutting force of 0. 031 % S steel is lower than that of common 0. 006% S steel ； As there are ≤6 μm MnS inclusions in 0. 031 % S steel

the chips are easily broken

and the manganese sulphide is able to clad

Al

2

O

3

spinel inclusions led to decrease of tool wear and increase of cutting characteristics of steel products.