By using JMatPro software and according to the 0. 70C steel coil (/%：0. 67C

0. 17Si

0. 50Mn

0. 010P

0. 010S

0. 10Cr) produced at steel works

the effect of C (0. 65% ~ 1. 00% )

Si (0. 20% ~ 0. 55% )

Mn(0. 50% ~ 1. 45%

Cr (0. 10% ~0. 75% )

S (0. 010%~0. 070% )

P (0. 010%~0. 060% ) and austenite grain ratting (5. 0 ~ 8. 0) in high carbon steel rod coil on martensite formation critical cooling rate (CCR

Mf

) has been simulate to get the predict high carbon steel CCR

Mf

expression: CCR

Mf

/(℃·s

-1

) =4. 088 -9

. 98 x [C

]

/% -3.58 x [Si

]

/% -5.12[Mn

]

/% - 0. 001 [P

]

/% +23. 45 x [S

]

/% -7.42 X [Cr

]

/% +2 x G

m

G

m

-austenite grain size rating. Results show that with increasing the C

Mn

Si and Cr content in steel the CCR

Mf

decreases

with increasing the S content in steel and original austenite grain size rating the CCR

Mf

increases and the effect of P on CCR

Mf

is minor； the effect of C and Mn on CCR

Mf

is largest； and the measure value of martensite formation critical cooling rate ( CCR

Mf

) of the 70C steel is 8. 51 ℃/s

and its calculated value is 8. 79℃/s with error 0. 28 ℃/s. It is suggested that during high carbon steel casting process the key point is to control C and Mn segregation and to fine austenite grain size during rolling process for decrease of formation of martensite structure.