1,100 MPa-grade high strength steel and production method thereof

Abstract

The invention relates to alloy steel. The alloy steel comprises the following chemical components in percentage by weight: 0.22 to 0.30 percent of C, 0.80 to 1.20 percent of Si, 2.00 to 2.50 percent of Mn, 0.08 to 0.15 percent of V, 0.015 to 0.10 percent of Nb, 0.01 to 0.04 percent of Ti, 0.015 to 0.05 percent of Al, and the balance of Fe and unavoidable impurities, wherein the total amount of the impurity elements is lower than 0.05 percent. The manufacturing of the steel provided by the invention comprises the following steps of: after steel making and hot rolling, cooling to the temperature of below 450 DEG C from the temperature of 850 DEG C in a forced way; cooling to room temperature along with air; and tempering at the temperature of 200 to 250 DEG C, wherein the tempering time is over 2.5 hours. The alloy steel provided by the invention has the tensile strength sigma b is greater than or equal to 1,100 MPa, and the elongation percentage delta 5 is greater than or equal to 15 percent. The alloy steel provided by the invention is simple in manufacturing process and does not need a complex thermal treatment process, so that energy resources are saved, the environment pollution is reduced, the production period is shortened and the manufacturing cost is reduced.

Description

technical field [0001] The invention relates to a high-strength alloy steel, in particular to a 1100MPa grade medium-low carbon non-quenched and tempered high-strength steel and a manufacturing method thereof. Background technique [0002] At present, non-quenched and tempered steel is generally used in the machinery manufacturing industry to replace carbon steel and alloy steel that need to be quenched and tempered, so as to save energy and alloy resources and reduce production costs. Since the 1970s, my country has successively developed a series of non-quenched and tempered steels with different strength grades, but most of the steel grades have low tensile strength grades, which limits their wide application. Although the tensile strength of a few steel types is above 1100MPa, their ductility and toughness indicators are low. They usually contain high C, or contain a certain amount of precious elements Cr and Mo, or require special processing to make the tensile strength...

AI Technical Summary

Problems solved by technology

[0005] CN1472358A discloses a non-quenched and tempered ultra-high carbon steel and its production process, wherein the content of C and Si is very high, and contains a certain amount of Cr element. Although the strength is high, the plasticity and toughness are low, and it adopts spray molding plus isothermal forging technology, which greatly increases the manufacturing cost

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