A longitudinally variable thickness ultra-high-strength ship plate and its production method

Abstract

The invention discloses a longitudinally variable-thickness ultra-high-strength ship plate and a production method thereof. The chemical composition of the steel plate is: C: 0.060%-0.120%, Si: 0.15%-0.50%, Mn: 1.10%-1.70%, V: 0.040%- 0.070%, Cu: 0.20%‑0.50%, Ni: 0.10%‑0.50%, Ti: 0.005%‑0.020%, N: 0.0120%‑0.0180%, P≤0.010%, S≤0.005%, Als: 0.015%‑ 0.030%. Molten steel is treated with nitrogen blowing in converter or RH, the billet is heated to 1130-1250°C, and held for 40min-240min; the rolling start temperature is 1040-1120°C, and the thickness of the cast billet is rolled to 2.0-3.0 times the maximum thickness of the final LP steel plate; The intermediate billet is rolled at a temperature of 850-910°C, and the rolling thickness is 1.5-2.0 times the maximum thickness of the final LP steel plate; variable thickness rolling is adopted, and the final rolling temperature of the steel plate is controlled at 800-850°C; the steel plate is air-cooled to room temperature to obtain the final Longitudinal variable thickness steel plate. The steel plate of the invention has good uniformity in mechanical properties along the length direction, the strength difference between thick and thin positions is within 15 MPa, and the toughness and plasticity are consistent, and is suitable for longitudinally variable-thickness high-strength ship plates of any shape.

Description

technical field [0001] The invention belongs to the technical field of metal material production, and in particular relates to a longitudinally variable-thickness ultra-high-strength ship plate and a production method thereof. Background technique [0002] Longitudinal variable thickness (LP) steel plate is a steel plate whose thickness changes along the length direction. It is a steel plate whose longitudinal thickness is changed by continuously changing the opening of the roll during the rolling process. According to the different ways of thickness change, it can be divided into 10 different types. shape. Since LP steel plate can change its thickness according to the load bearing conditions, it has unique advantages in optimizing the design of structural sections such as the hull. The equal thickness of the steel plate improves its operability, such as omitting the backing plate and taper processing. In recent years, with the increase in the demand for lightweight ships, ...

AI Technical Summary

Problems solved by technology

[0005] 1) High alloying elements and high production costs

[0006] 2) The uniformity of the mechanical properties of the steel plate along the length direction is poor

[0007] 3) The production process is complex

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