High-strength high-toughness Cu-containing steel and production method thereof

Abstract

The invention provides high-strength high-toughness Cu-containing steel and a production method thereof. The steel comprises the following chemical components in percent by weight: 0.04-0.07 percent of C, 0.25-0.45 percent of Si, 0.60-1.00 percent of Mn, 0.01-0.03 percent of Als, 2.40-3.20 percent of Ni, 1.20-1.60 percent of Cu, 0.65-0.90 percent of Cr, 0.30-0.60 percent of Mo, 0.02-0.04 percent of Nb, 0.01-0.03 percent of Ti, less than or equal to 0.015 percent of P, less than or equal to 0.010 percent of S and the balance of iron and inevitable impurities. The production method comprises the following steps of: performing total molten iron smelting by using a duplex process, performing external refining through converter top-blown or top and bottom composite blowing, performing whole-course protection casting during continuous casting, and slowly cooling after a continuous casting billet is off line; controlling the heating temperature of the billet to be 1,150-1,250 DEG C and the heating time to be 3.5-5 hours, controlling the open rolling temperature to be 1,050-1,100 DEG C during rough rolling, controlling the open rolling temperature to be 890-920 DEG C during finish rolling, and controlling the finished rolling temperature to be 800-860 DEG C during finish rolling; performing heat treatment, wherein the quenching temperature is 860-920 DEG C, the temperature keeping time is 0.5-3.5 hours; and performing water cooling; keeping the tempering temperature to be 620-690 DEG C, wherein the temperature keeping time is 1-7 hours; and performing air cooling. The steel plate has the yield strength of more than or equal to 690MPa, the Charpy impact work of a V-shaped notch at the temperature of 80 DEG C below zero is more than 120J, and the ductile-brittle transition temperature is lower than 80 DEG C below zero.

Description

technical field [0001] The invention relates to Cu-containing steel with yield strength ≥ 690 MPa, good low-temperature toughness (-80°C) and low ductile-brittle transition temperature and a production method thereof, belonging to the field of low-alloy steel manufacturing. Background technique [0002] Low-carbon (high-strength) low-alloy steel is one of the important engineering structural materials, and is widely used in offshore platforms, shipbuilding, boiler pressure vessels and bridges. It is difficult for general steel to have good low temperature toughness while ensuring high strength. With the development of science and technology, people have put forward higher requirements for the strength and toughness of steel. , in order to reduce the weight of the hull, increase the load capacity of the ship, and increase the speed of the ship, the ship plate steel is required to have higher strength, higher toughness, and certain corrosion resistance. [0003] The study fo...

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Problems solved by technology

[0006] Patent 200810035367 introduces a method for manufacturing Cu-containing high-strength and tough steel, but it is mainly used for the production of thin slabs, and the thickness of the finished product is relatively thin

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