Normalized high-strength steel plate and manufacturing method thereof

Abstract

The invention relates to a normalized high-strength steel plate. The normalized high-strength steel plate is prepared from the chemical compositions in percentage by weight: 0.15-0.20% of C, 0.20-0.50% of Si, 1.30-1.60% of Mn, less than or equal to 0.020% of P, less than or equal to 0.015% of S, 0.01-0.035% of Nb, 0.04-0.08% of V, 0.15-0.30% of Cr, 0.025-0.04% of Al, 0.006-0.022% of N, 0.0008-0.005% of O, less than or equal to 0.04% of As, less than or equal to 0.03% of Sn, less than or equal to 0.0002% of H, and the balance of Fe and unavoidable impurities. According to the manufactured steelplate, the yield strength is greater than or equal to 400 Mpa, the tensile strength is greater than or equal to 570 Mpa, the elongation is greater than or equal to 18%, the Charpy impact energy Akv (-60 DEG C) reaches 40 J or above, the impact energy unit value is 30 J or above, and the average grain size of ferrite is 10 [mu]m or below. The process cost is lowered while strength, tenacity and weldability are guaranteed.

Description

technical field [0001] The invention belongs to the technical field of metallurgical manufacture, and relates to a normalized high-strength steel plate with a tensile strength of 570 MPa and a manufacturing method thereof. Background technique [0002] With the domestic demand for green manufacturing, in order to reduce the amount of materials or reduce the weight of materials, the building structure and pressure vessel industries are developing in the direction of lightweight. The strength of normalized steel plates is changed from the traditional tensile strength of 490MPa to 530, 570, and 590MPa. With the development of steel, the amount of high-strength normalized steel plate is showing a continuous increase trend. [0003] In the prior art, there are documents introducing normalized high-strength steel plates with a tensile strength of 590 MPa. [0004] Chinese patent CN104878294A discloses "a P440NL1 steel plate for oil tanker and its production method", which is comp...

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Problems solved by technology

[0007] It can be seen from the above that in the prior art, in order to obtain a high-toughness 570MPa-grade normalized high-strength steel plate, high V and N are mainly used to increase the strength, which requires high purity, and at the same time, precious Cu and other alloys need to be added. Elements not only increase the production cost of steel enterprises, but also increase the production cost of downstream users

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