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...

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