700 MPa grade low temperature quenched and tempered steel plate with excellent weldability and fatigue resistance and manufacturing method thereof

Abstract

The invention discloses a 700 MPa grade low temperature quenched and tempered steel plate with excellent weldability and fatigue resistance and a manufacturing method thereof. The steel plate comprises the following components in percentage by weight: 0.050-0.090% of C, less than or equal to 0.15% of Si, 1.30-1.60% of Mn, less than or equal to 0.013% of P, less than or equal to 0.0030% of S, 0.10-0.35% of Cu, 0.50-0.90% of Ni, 0.15-0.35% of Cr, 0.15-0.35% of Mo, 0.008-0.030% of Nb, 0.030-0.060% of V, 0.008-0.014% of Ti, 0.030-0.060% of Al, less than or equal to 0.0003% of B, less than or equalto 0.0050 % of N, 0.0010 -0.0040% of Ca, and the balance Fe and inevitable inclusions. A component system of ultra-low C-Mn-(Ti plus Nb plus V) microalloyed steel is adopted as a substrate, so that an excellent fit of strength, ultra-low temperature toughness and strength-toughness of the 700 MPa grade low temperature quenched and tempered steel plate is obtained, and the weldability and machinability of the steel plate are also excellent.

Description

technical field [0001] The invention relates to a 700MPa low-temperature quenched and tempered steel plate with excellent weldability and fatigue resistance and a manufacturing method thereof. 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 containers, building structures, automobile industry, railway transportation and machinery manufacturing. middle. 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 the most important properties of low-carbon (high-strength) low-alloy steel, which are ultimately determined by the finished steel state of the microstructure. With the continuous development of science and technology, people put...

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Problems solved by technology

[0006] A large number of existing patent documents only explain how to realize the strength and low-temperature toughness of the base steel plate, improve the weldability of the steel plate, and obtain excellent low-temperature toughness of the welding heat-affected zone HAZ. , improve the tensile elongation of the steel plate, the uniformity of mechanical properties in the thickness direction, excellent machining performance and fatigue crack growth resistance (Japanese patents Zhao 63-93845, Zhao 63-79921, Zhao 60-258410, special flat opening 4- 285119, special flat opening 4-308035, flat 3-264614, flat 2-250917, flat 4-143246, US Patent 5798004, European Patent EP 0288054A2

[0007] There are also Chinese patents ZL201210077114.7, ZL201110181293.4, ZL201010113835.X, ZL200910196233.2, ZL200810042088.8, ZL200810042124.0. Major breakthroughs and good results have been achieved in issues such as low-cost manufacturing, specification expansion of extra-thick steel plates, and performance uniformity in the thickness direction of extra-thick steel plates. The steel plates have achieved mass industrial production and have been successfully applied to major domestic and foreign construction projects and major equipment manufacturing. Good supply performance has been achieved, some varieties have replaced imports, filling the domestic gap, especially the successful development of anti-strain aging embrittlement and eliminating residual stress annealing embrittlement extra-thick 600MPa quenched and tempered steel plate (such as Chinese patent ZL201610463494.6), not only obtained It has excellent low-temperature toughness and anti-SR embrittlement and softening properties, and solves the shortcomings of weak intrinsic fatigue resistance of high-strength tempered steel plates; but the strength of steel plates only involves 600MPa levels, and higher strength levels have not yet been involved

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