| 摘要 |
<p>High strength heat-resistant low alloy steels, which comprises, on the weight basis, a carbon content of 0.03 - 0.12 %, a silicon content not higher than 1 %, a manganese content of 0.2 - 1 %, a phosphor content not higher than 0.03 %, a sulfur content not higher than 0.03 %, a nickel content not higher than 0.8 %, a chromium content of 0.7 - 3 %, a vanadium content of 0.05 - 0.35 %, a niobium content of 0.01 - 0.12 % and a nitrogen content of 0.01 - 0.05 % with the balance of iron and inevitable impurities. According to a first aspect of the invention, the steel has further a molybdenum content of 0.3 - 0.7 % and a wolfram content of 0.6 - 2.4 %, wherein the molybdenum content and the wolfram content satisfy the relationship 0.8 %</= (Mo + 1/2 W) % </= 1.5 %; according to a second aspect of the invention, the steel has also a molybdenum content of 0.3 - 1.5 %, and occasionally, a further content of one or more of wolfram, in a content of 0.5 - 2.4 %, boron, in a content of 0.0005 - 0.015 %, aluminum, in a content not higher than 0.05 %, and titanium, in a content of 0.05 - 0.2 %, with the balance of iron and inevitable impurities. This low alloy steels are obtained by subjecting a steel having the above mentioned chemical composition to a heat treatment by heating it to a temperature above 1100 DEG C (A) and subsequent cooling to room temperature, then, subjecting the so treated metal to a plastic working at a temperature in the range from room temperature to a temperature at which no recrystallization occurs during the working or in the course of subsequent cooling and, finally, subjecting the so worked metal to a normalizing at a temperature lower than 1100 DEG C (A) and to a tempering at a temperature below the Ac1 point.</p> |
