| 摘要 |
<p>A first steel comprises 0-0.05 weight % carbon, 0-1.0 weight % silicon, 10.0-20.0 weight % manganese, 13.5-18.0 weight % chromium, 1.0-4.0 weight % nickel, 1.5-3.5 weight % molybdenum and 0.2-0.4 weight % nitrogen. A second steel comprises 0-0.2 weight % carbon, 0-1.0 weight % silicon, 10.0-20.0 weight % manganese, 13.5-18.0 weight % chromium, 1.0-7.0 weight % nickel, 1.5-4.0 weight % molybdenum and 0.2-0.4 weight % nitrogen where nickel equivalence/(chromium equivalence - 1À4) > 1.51 and nickel equivalence + chromium equivalence > 35. Such steels may be used as drill collars in oil and gas drills.</p> |
