High-quality steel plate capable of resisting fatigue crack growth and manufacturing method thereof

Abstract

The invention discloses a high-quality steel plate capable of resisting fatigue crack growth and a manufacturing method thereof. The high-quality steel plate comprises the following constituents in percentage by weight: 0.040-0.070% of C, 0.40-0.70% of Si, 1.30-1.60% of Mn, less than or equal to 0.013% of P, less than or equal to 0.003% of S, less than or equal to 0.30% of Cu, less than or equal to 0.30% of Ni, less than or equal to 0.10% of Mo, 0.008-0.018% of Ti, 0.015-0.030% of Nb, less than or equal to 0.0040% of N, 0.0010-0.0040% of Ca, and the balance of Fe and unavoidable impurities. The manufacturing method comprises the following steps: using the ultra-low carbon C-high Si-intermediate Mn-Nb system low alloy steel as a base, controlling [%C]*[%Si] to be 0.022-0.042 and {([%C]+3.33[%Nb])*[%Si]}*V cooling velocity / T cold shutdown to be from 1.15*10<-4> to 2.2*10<-3>, carrying out Ca treatment, enabling Ca / S to be equal to 1.0-3.0 and (%Ca)*(%S)<0.28> to be smaller than or equal to 1.0*10<-3>, optimizing the TMCP technology, enabling the finished product steel plate microscopic structure to become a ferrite and uniformly dispersed bainite dual-phase structure, and allowing the average grain size of the microscopic structure to be 10 microns below.

Description

technical field [0001] The present invention relates to a steel plate with excellent fatigue crack growth resistance and a manufacturing method thereof. The yield strength of the steel plate is ≥385MPa, the tensile strength is 520-630MPa, the Charpy impact energy (single value) at -40°C is ≥80J, and the fatigue crack growth resistance is excellent. Steel plate (at ΔK=8MPa·m 1 / 2 Under conditions, da / dN≤3.0×10 -8 ). Background technique [0002] As we all know, low-carbon (high-strength) low-alloy steel is one of the most important engineering structural materials, widely used in oil and gas pipelines, offshore platforms, shipbuilding, bridge structures, boiler pressure vessels, building structures, automobile industry, railway transportation and machinery under manufacture. The properties of low-carbon (high-strength) low-alloy steel depend on its chemical composition and the process system of the manufacturing process, among which strength, toughness and weldability are t...

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Problems solved by technology

[0004] Japan's Sumitomo Metal has successfully developed a thick steel plate FCA with excellent weldability, fatigue crack growth resistance, and a yield strength of 355MPa (such as the "steel plate with fatigue crack crack growth suppression" disclosed in Japanese Patent No. 3298544; Japanese Patent Application No. 10-60575 The published "thick steel plate with excellent fatigue crack suppression characteristics") has achieved good practical results and realized batch supply, but the development of steel plate did not involve thick steel plate of higher strength level

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