| 摘要 |
PURPOSE:To improve the strength and toughness of a steel for a chain used in a frozen sea area by regulating the composition of the steel so as to properly combine specified amounts of components. CONSTITUTION:The composition of a steel for a chain is composed of, by weight, 0.15-0.35% C, 0.15-0.50% Si, 1.00-2.00% Mn, <=0.50% Cr, 0.10-0.60% Mo, 0.010-0.100% acid-sol. Al and the balance Fe. The composition may further contain 0.01-0.10% each of one or more among V, Nb and Ti. A round bar of the steel is cut to a prescribed length, hot bent, joined by flash butt welding and subjected to heat treatment such as normalizing or hardening and tempering to provide high strength and toughness. The resulting chain used in a frozen sea area has >=70kgf/mm<2> tensile strength and the base metal and the weld zones have >=2.8kgfm Charpy impact value at -60 deg.C. By this method, a high strength and high toughness chain of a large diameter can be manufactured.
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