Structure of heat-resistant steel 1 Crl2Ni3Mo2VN quenched at 1 040 T for 1 h oil cooling

furnace cooling (5 T/min)

1 °C./min and 0. 5 °C/min cooling and mechanical properties of the steel quenched at 1 040 °C for 1 h with different cooling rate + tempered at 565 °C for 2 h have been studied. Test results show that martensite structure of the steel quenched with four cooling rate is obtained

but A

KV2

value of the steel by quenching

oil cooling and tempering is 156. 5 J

while that by quenching

5 ~0. 5 °C/min cooling and tempering is 40. 5 - 16. 5 J. The thermal decomposition of retained austenite in steel slow-cooled is main reasons for impact energy marked decreasing

i. e. during quenching slow- cooling at 720 ~ 820 °C

a large amount of carbide precipitates at original austenite grain boundary led to obvious decreasing alloying el

ements and carbon content in residual austenite and poor stability of residual austenite in quenched structure.