Steel for furnace valves - with high resistance to thermal fatigue and good weldability by alloying with molybdenum and vanadium

摘要

The steel contains 0.1% max. C, 0.5% max. Si, 1.5% max. Mn, 0.5-1.0% max. Mo, 0.02-0.2% V, 0.05% max. Al, 0.10% max. opt. singly or together Nb, Ta, Ti, rare earth metals, and 0.006% max. B, and conforming to: (1) 30(%C) + 5(%Si) + (10(%Mn) + 40(%Mo) + 50(%V) + 60(%Ti+Nb+Ta) 50(%RE) + 1000(%B) >=36 (2) (%C) + 1/30(%Si) + 1/20(%Mn) + 1/20(%Cu) + 1/60(%Ni) + 1/20(%Cr + 1/15(%Mo) + 1/10(%V) + 5(%B) 0.22. The steel valves are partic. useful for hot blast furnaces with water cooled valves. The steel has high resistance to thermal fatigue with large temp. differences in water cooled parts. A typical steel contains 0.08% C, 0.21% Si, 0.72% Mn, 0.016%P, 0.016%S, 0.53%MN, 0.09%V, 0.024%Al.