Steel for high-strength, high-toughness, corrosion-resistant chains and heat treatment method thereof

Abstract

The invention discloses high-strength high-toughness corrosion-resistant chain steel. The steel comprises, by weight, 0.06-0.11wt.% of C, 0.15-0.35wt.% of Si, 0.30-0.50wt.% of Mn, 1.00-3.00wt.% of Cr, 2.00-4.00wt.% of Ni, 0.30-0.60wt.% of Mo, 0.02-0.06wt.% of Nb, 0.03-0.09wt.% of V, 0-0.015wt.% of P, 0-0.015wt.% of S, and the balance Fe and inevitable impurities. A vertical continuous heat treatment furnace and the double-quenching heat treatment and one-time tempering heat treatment processing mode are adopted in heat treatment of a chain. The chain sequentially passes through an A austenitizing heating furnace, an A quenching tank, a B austenitizing heating furnace, a B quenching tank and a C tempering heating furnace. A lath martensite structure with the lath block width being 0.3-5 microns can be obtained by means of heat treatment, and granular cementite with the diameter being 0.2-0.8 micron and the volume fraction being 0.15%-0.35% and MC phase particles with the diameter being 5-15nm and the volume fraction being 0.02%-0.08% are distributed between laths and inside the laths in a dispersed mode. The tensile strength of the chain reaches 1000MPa level after heat treatment, the loop back and welded joint KV2(-60 DEG C) can reach 100 or above, and seawater corrosion resistance is good.

Description

technical field [0001] The invention belongs to the fields of steel for marine anchor chains and steel for marine engineering mooring chains, and in particular relates to steel for high-strength, high-toughness, corrosion-resistant chains and a heat treatment method thereof. Background technique [0002] Petroleum exploration and production has developed from the offshore to the deep sea, and is gradually advancing to the polar ocean. Traditional marine anchor chains and mooring chains only require the assessment of -20°C impact energy indicators, which can no longer meet the low-temperature impact resistance requirements of icebreakers and polar ocean platforms. In addition, marine anchor chains and mooring chains are exposed or immersed in marine atmospheric environment or seawater environment for a long time, and severe corrosion is also one of the main forms of failure. Traditional marine anchor chains use C-Mn steel, which has not been upgraded for decades; the technol...

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Problems solved by technology

Traditional marine anchor chains use C-Mn steel, which has not been upgraded for decades; the technology or patents of mooring chains in the past ten years have mainly developed in the direction of large specifications and high strength, and the C content of high-strength mooring chains has remained at Above 0.16wt.%, the content of Mn, Cr, and Mo increases gradually, and the progress of metallurgical technology largely solves the conventional low-temperature impact toughness requirements, but the ultra-low temperature impact toughness has not attracted enough attention

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