High-performance quenched and tempered steel plate with 80 kg carbon equivalent and manufacturing method of high-performance quenched and tempered steel plate

Abstract

The invention provides a high-performance quenched and tempered steel plate with 80 kg carbon equivalent and a manufacturing method of the high-performance quenched and tempered steel plate. The high-performance quenched and tempered steel plate comprises the following ingredients by weight percent: 0.05 to 0.12 percent of C, 0 to 0.20 percent of Si, 1.20 to 1.60 percent of Mn, 0 to 0.013 percent of P, 0 to 0.003 percent of S, 0.10 to 0.30 percent of Cu, 0.10 to 0.40 percent of Ni, 0.10 to 0.30 percent of Cr, 0.05 to 0.30 percent of Mo, 0.035 to 0.065 percent of Als, 0.005 to 0.011 percent of Ti, 0.015 to 0.045 percent of V, 0 to 0.0060 percent of N, 0.001 to 0.004 percent of Ca, 0.0006 to 0.0013 percent of B, and Fe in balancing amount. By adopting a low-C low-Si high-Mn low-N-(Ti+N+B) microalloyed steel ingredient system as the foundation, and optimizing recrystallization rolling control, quenching and tempering process, the invention has the advantages that the microstructure of the steel plate is tiny tempered martensite or tempered lower bainite; the average size of colonies is lower than 25 Mum; the yield strength is larger than or equal to 690MPa; the tensile strength is larger than or equal to 780 MPa; the Charpy impact power (single value) at -40 DEG C is equal to or larger than 100 J; moreover, the Charpy impact power (single value) of a welding heat affected zone (HAZ) at -40 DEG C is equal to or larger than 47 J, and the stretch rate Delta 5 thereof is equal to or larger than 15 percent.

Description

technical field [0001] The invention relates to a method for manufacturing quenched and tempered steel plates, in particular to low-carbon equivalent 80 kg high-performance quenched and tempered steel plates and a manufacturing method thereof. The yield strength of quenched and tempered steel plates is ≥ 690 MPa, the tensile strength is ≥ 780 MPa, and Charpy impact energy at -40 °C (single value) ≥ 100J, excellent weldability, that is, Charpy impact energy (single value) ≥ 47J in the welding heat-affected zone (HAZ) at -40°C, elongation δ 5 ≥15%, the microstructure of quenched and tempered steel plate is fine tempered martensite + tempered lower bainite. 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...

AI Technical Summary

Problems solved by technology

In this way, not only the alloy content of the steel plate is high, but also the carbon equivalent Ceq and the welding cold crack sensitivity index Pcm are high, which brings great difficulties to on-site welding. Preheating before welding and heat treatment after welding are required, and welding costs increase. , Welding efficiency is reduced, and the working environment of the welding site is deteriorated; and the manufacturing cost of the steel plate is also greatly increased, which affects the market competitiveness and popularization of the steel plate

Although the strength, low-temperature toughness and elongation of the steel plate produced by this quenching and tempering process can meet the requirements of users, the manufacturing cost of the steel plate is high, and the welding processing cost is high. Except for container, offshore platform and other engineer

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