Ultra-wide specifications, high-strength and high-toughness marine engineering steel and manufacturing method thereof

Abstract

The invention discloses ultra-wide high-strength high-toughness steel for marine engineering and a manufacturing method thereof. The steel comprises 0.05 to 0.10% of C, 0.10 to 0.50% of Si, 1.2 to 1.5% of Mn, 0.20 to 0.40% of Cu, 0.10 to 0.30% of Ni, no more than 0.01% of P, no more than 0.01% of S, 0.01 to 0.05% of Als, 0.020 to 0.040% of Nb, 0.010 to 0.020% of Ti and 0.040 to 0.070% of V. According to the invention, a heating temperature is 1,150 to 1,200 DEG C, and heat preservation is performed for 30-60 min; in a first stage, rolling temperature is 1,000-1,050 DEG C, and an average single-pass reduction rate is no less than 15%; in a second stage, rolling temperature is 850-950 DEG C, and an average single-pass reduction rate is no less than 15%; in a third stage, rolling temperatureis 800-830 DEG C, and an average single-pass reduction rate is more than 10%; and an average cooling rate is more than 3 DEG C / s, a self-tempering temperature is 600-650 DEG C, and slow cooling time is no less than 24h. A manufactured steel plate has a width of 3,500 to 4,500 mm and is high in strength and excellent in low-temperature toughness.

Description

technical field [0001] The invention belongs to the field of iron and steel material preparation, and relates to a steel plate with ultra-wide specifications, thick specifications, high strength, and excellent low-temperature toughness characteristics, especially the strength at the 1 / 4 and 1 / 2 positions of the plate thickness direction, excellent low-temperature impact energy and fracture toughness and methods of manufacture thereof. Background technique [0002] With the increasing demand for large-scale marine transportation and mining equipment, the demand for equipment materials for marine engineering is increasing, and the requirements are also increasing. Steel plates for offshore platforms must have strict requirements for ultra-wide specifications, high strength, high toughness, good weldability and thick specifications, especially the fracture toughness of materials. [0003] The ultra-wide high-strength toughness steel plate can save welding work and improve the ...

AI Technical Summary

Problems solved by technology

The patent composition design is as follows: C: 0.01% ~ 0.06%, Si: 0.01% ~ 0.8%, Mn: 1.0% ~ 1.8%, Al: 0.01% ~ 0.08%, Nb: 0.02% ~ 0.08%, Ni: 0.20% ~0.8%; the width of the steel plate obtained by this patented technology cannot reach 4000mm, which cannot guarantee the special needs of large container ships for special purposes and marine mining equipment

[0005] CN200910147530.8 proposes a method for preparing thick plate steel with brittle crack propagation stop characteristics. The composition of the patent is designed as follows: C: 0.05% to 0.12%, Si: 0.05% to 0.30%, Mn: 1.00% to 1.80%, Al: 0.01% to 0.06%, Ti: 0.005% to 0.03%, Nb: 0.005% to 0.05%, B: 0.0005% to 0.003%, N: 0.0020% to 0.0090%; in this technology, the thickness direction cannot be guaranteed Requirements such as toughness, strength and microstructure uniformity at t / 4~t / 2 positions; in addition, this technical requirement requires cooling, rolling and reheating processes during the rolling process, making the manufacturing process more complex and increasing the actual Difficulty in operation, which affects the actual yield, and the patented technology can obtain a steel plate width of less than 4000mm

[0006] CN103451534B proposes a steel plate for offshore platforms with excellent performance in the thickness direction of 60mm and its production method. The composition of the patent is designed as follows: C: 0.09-0.14%; Si: 0.20%-0.50%; Mn: 1.10%-1.50%; P≤ 0.015%; S≤0.005%; Al: 0.015% ~ 0.050%; Nb: 0.030% ~ 0.060%; Ti: 0.010% ~ 0.020%; the steel plate strength and low temperature toughness achieved by this patent have not achieved good fracture toughness , the patented technology can get the steel plate width less than 4000mm

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