Marine ultrahigh-strength low-temperature steel with excellent fatigue performance and manufacturing method

Abstract

The invention provides marine ultrahigh-strength low-temperature steel with excellent fatigue performance and a manufacturing method thereof. The steel comprises the following components in percentage by weight: 0.080%-0.140% of C, 0.20%-0.60% of Si, 1.15%-1.60% of Mn, 0.020%-0.050% of Nb, 0.040%-0.080% of V, 0.30%-0.50% of Cu, 0.50%-0.80% of Ni, 0.0140%-0.057% of N, 0.10%-0.20% of Cr, less than or equal to 0.010% of P, less than or equal to 0.005% of S, 0.015%-0.035% of Als and the balance of Fe and inevitable impurities. The preparation method comprises the steps of smelting, continuous casting, heating, rolling and cooling. The microscopic structure of the low-temperature steel produced through the method is a complex-phase structure of superfine ferrite, bainite and a small amount of martensite, the room-temperature high-cycle fatigue ultimate strength is 320 MPa or above, the fatigue ratio is larger than or equal to 0.52, and the-20 DEG C high-cycle fatigue ultimate strength is 350 MPa or above; according to the low-temperature steel, the yield strength is 500 MPa or above, the tensile strength is 620 MPa or above, the percentage elongation after fracture is 23.0% or above, the impact absorption energy at the temperature of-40 DEG C is larger than or equal to 260 J, and the impact absorption energy at the temperature of-60 DEG C is larger than or equal to 230 J.

Description

technical field [0001] The invention belongs to the field of metal materials, and in particular relates to a marine ultra-high-strength low-temperature steel with excellent fatigue properties and a manufacturing method. Background technique [0002] In recent years, with the development of the "Arctic Route", more and more polar ships have been invested in the development and expansion of the Arctic route, and the demand for polar ships with ice-breaking capabilities is increasing. Usually, there are two ways for icebreakers to break ice. One is continuous ice breaking, and the other is impact ice breaking. No matter what method is used to break ice, the ice breaking area of ​​the ship will be continuously hit by ice blocks, thereby causing damage to the ship. Therefore, the development of polar ships has put forward higher requirements for the performance of shipbuilding steel plates. First, as a material for long-term service in ice areas, it should have good low temperatu...

AI Technical Summary

Problems solved by technology

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

[0006] 2) The low temperature toughness of the steel plate is not enough to meet

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