The forging of steel 30CrMoA (/%: 0. 30C

0.21 Si

0. 53Mn

0. 003S

0. 005P

0. 98Cr

0.22Mo

0. 06 V) for Desander is a tubular stock with outside diameter Φ405 ~493 mm and inside diameter Φ90 - 167 mm and in specification the transverse impact energy of quenched-tempered steel at -40 °C is ≥20 J. With conventional normalizing + quenching+ tempering process: 920 ℃ normalizing (fan cooling) +880 °C normalizing (fan cooling) +860 ℃ quenching (air cooling + water cooling) +630 ~680 ℃ tempering ( air cooling) the transverse R

m

of steel is 715 ~815 MPa

R

p0.2

545 〜665 MPa

A 19% ~

20%

Z 65% ~68%

ambient A

kv

36 ~ 101 J and -40 %： A

kv

11 ~21 J； with equilibrium phase diagram calculated by Thermo-calc software and calculated A

c3

value of steel t the optimum normalizing + quenching+ tempering process has been defined that is 950 °C normalizing ( fan cooling) + 820 ℃ quenching (air cooling + water cooling) + 660 ~670 ℃ tempering (air cooling)

and with the optimum process the transverse mechanical properties of steel are R

m

685 〜700 MPa

R

p0.2

500 〜525 MPa

A 21% 〜22%

Z63% 〜66%

ambient A

kv

65 ~ 114 J and -40 °C A

kv

23 〜28 J

all meet the requirement of specification for the steel.