High-performance marine mooring chain steel and manufacturing method thereof

Abstract

The invention relates to high-performance marine mooring chain steel and a manufacturing method thereof. The method comprises the following steps: a. tapping compositions comprise the following by weight percentage: C: 0.16 to 0.27, Mn: 0.40 to 1.45, Si: 0.15 to 0.50, Cr: 1.25 to 2.50, Ni: larger than 0 and less than 1.20, Mo: 0.20 to 0.60, Al: 0.01 to 0.06, N: 0.004 to 0.015, S: not larger than 0.005, P: not larger than 0.015, Cu: larger than 0 and less than 0.50, and the balance of Fe; b. a steel ingot or a continuous casting billet is casted after the steps of primary smelting in an electric stove or a converter, external refining and vacuum degassing; c. the charging temperature of a heating oven is not larger than 900 DEG C, the heating rate is not larger than 150 DEG C / h; when being raised to 1100 to 1300 DEG C, the temperature is kept for more than 40 minutes, cogging bloom or rolling by a finisher is carried out, and the finishing temperature is not larger than 1050 DEG C; and d. after heated at the temperature of 1000 to 1250 DEG C, the cogged ingot is hot-rolled or forged into round steel, the finishing temperature is not larger than 1050 DEG C, and after rolling, the steel is air-cooled, slow cooled or softening heat-treated at the temperature of not less than 600 DEG C. The performance of finished products achieves or exceeds the requirement of level 4.5 and level 5 of mooring chain steel.

Description

technical field [0001] The invention belongs to the field of low-alloy steel, in particular to a high-performance marine mooring chain steel and a manufacturing method thereof. Background technique [0002] Mooring chain steel can be divided into three grades (R3), three and a half grades (R3S), and four grades (R4) according to their strength levels. It has high plasticity, toughness and safety requirements of yield ratio ≤0.92. At present, the highest grade of mooring chain steel approved by the classification societies of various countries is grade 4. [0003] In recent years, with the in-depth development of marine resources, the number of marine facilities used for deep-sea oil extraction and marine exploration has increased globally, and the demand for large-diameter mooring chains of 60-160 mm to moor these facilities has also increased. On the other hand, although marine facilities tend to be large-scale and high-strength, due to the limitation of their loading wei...

AI Technical Summary

Problems solved by technology

[0014] The main purpose of the present invention is to provide a high-performance marine mooring chain steel and its manufacturing method. By redesigning the alloy composition and adjusting its manufacturing method, the problems of insufficient performance and unsatisfactory heat treatment process of the existing mooring chain steel can be solved, and the overall improvement can be achieved. The performance of mooring chain steel and mooring chain after overall heat treatment, namely tensile strength ≥ 1000Mpa, yield ratio ≤ 0.92, elongation ≥ 12%, reduction of area ≥ 50%, impact energy -20℃Akv) ≥ 58J

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