A method for manufacturing marine engineering steel with high strength and high toughness

Abstract

The invention belongs to the field of steel material preparation and relates to a method for manufacturing steel for marine engineering with high strength and high toughness. The chemical composition in the target steel includes C: 0.07-0.15%, Si: 0.10-0.40%, Mn: 0.60-1.50%, Ni: 3.00-9.0%, Cr: 0.40-0.60%, Mo: 0.40-0.80% by weight percentage , V: 0.07~0.16%, P: ≤0.003%, S: ≤0.002%, the rest is Fe and unavoidable impurities; raw materials are prepared according to the composition of the target steel; combined with high temperature hot rolling-on-line quenching + subcritical two-phase region The tempering heat treatment process realizes the production of steel plates with high strength, low yield ratio and low temperature toughness at the same time, and obtains steel plates with high yield, stable strength and low temperature toughness. The steel plate of the invention has the characteristics of high strength (yield strength ≥ 1000MPa), low yield ratio (≤ 0.93), elongation after fracture ≥ 20%, and excellent low-temperature toughness (-80°C impact energy ≥ 220J).

Description

technical field [0001] The invention belongs to the field of iron and steel material preparation, and relates to a method for manufacturing marine engineering steel with high strength and high toughness. Background technique [0002] In the past ten years, the development of marine resources has been intensified, and marine engineering and other fields have developed rapidly. The development of high-end manufacturing is inseparable from the development of advanced materials. High-end marine engineering steel not only requires materials with high strength, high toughness, Achieving light weight also requires materials with weldability and low yield ratio properties to ensure reliability during safe service. In addition, the difficulty of resource extraction has increased, and the demand for ultra-high-strength structural materials has also increased. Therefore, structural steels with high strength, easy welding, low yield ratio and excellent low temperature toughness have im...

AI Technical Summary

Problems solved by technology

The current production of ultra-high-strength steel for marine engineering has the following deficiencies: (1) The steel plate characterized by tempered martensite increases with the yield, and the yield-strength ratio approaches 1, which seriously affects the safety of the material; (2) ) The low-temperature toughness of marine engineering steel above 890MPa level is insufficient, which cannot meet the construction of marine engineering projects in extremely cold regions; (3) The construction of advanced marine equipment requires higher strength marine engineering steel, and the yield strength needs to be further increased to 1GPa level above

The patented composition adds micro-alloying element Nb: 0.01-0.05%, and adopts multi-stage cooling, and the process is complicated

In addition, the yield strength of the steel plate produced by this technology is low

[0008] At present, the microstructure of low-alloy high-strength steel with a yield strength of more than 600MPa is mostly tempered martensite. This type of steel has problems such as insufficient toughness, high yield ratio and decreased plasticity during use. This is due to the single The martensitic structure has a high dislocation density, resulting in high strength, high yield ratio and low toughness characteristics

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