The metallurgical flowsheet for tested steel 5Cr5WMoSiV ( HYRH12

/%: 0.53C

0.30~1. 10Si

0.35Mn

≤0.025P

≤0.010S

5.30Cr

1.30Mo

1.20W

0.50V) is 3t induction furnace-780kg ESR- annealing-110mm square billet forging-Φ42. 5 mm rolled bar-Φ14mm rolled products. The effect of 0.03%~1.10% Si and 1010~1070°C quenching +510〜550°C tempering treatment on metallurgical quality

structure and mechanical properties of steel 5Cr5WMoSiV has been studied. Results show that the Si is obvious to promote the precipitation of carbides in steel and markedly to increase the hardness of steel; in steels containing 0.3%

0.7% and 1.1%Si

the toughness and strength of 0.7%Si steel are lowest

but the toughness and bending strength of 0.3%Si steel is highest；the HRC harness value of 1.1%Si steel quenched at 1060~1080°C is up to 64. As service for cold-rolling mill middle roll

the suitable Si content in steel 5Cr5WMoSiV is 1.0%~1.2%

the recommended heat treatment process for steel 5Cr5WMoSiV is quenching at 1030~1070°C and tempering at 520~540°C.