High-strength steel plate with yield strength 1,000 MPa and production method thereof

Abstract

The invention discloses a high-strength steel plate with the yield strength 1,000 MPa and a production method thereof. The steel plate comprises the following chemical components in percentage by weight: 0.05-0.08 percent of C, 0.1-0.3 percent of Si, 1-2 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.007 percent of S, 0.3-0.7 percent of Ni, 0.3-0.5 percent of Cr, 0.3-0.6 percent of Mo, 0.02-0.04 percent of Nb, 0.03-0.055 percent of V, 0.01-0.035 percent of Ti, 0.002-0.0035 percent of B and the balance of Fe and inevitable impurities, wherein the gas content [O] is controlled to be less than or equal to 0.002 percent and [N] is controlled to be less than or equal to 0.004 percent, Ti / N is more than or equal to 3.2, and the carbon equivalent index Ceq is less than or equal to 0.56 percent. The production method comprises the following steps of: performing continuous casting with an electromagnetic stirring technology, wherein the thickness of a continuously cast bloom after casting is not less than four times that of a finished steel plate; and heating a steel blank at the temperature 1,100-1,200 DEG C, rolling in a recrystallization region and a non-recrystallization region at two stages, performing relaxation temperature waiting for 5-20 seconds, quickly cooling to 300-450 DEG C at the speed 10-30 DEG C per second, draining water, stacking, slowly cooling, tempering the steel plate at the tempering temperature 400-600 DEG C, and preserving heat for 2-3 minutes per millimeter. The steel plate has high comprehensive performance, large specification coverage and greatly-lowered production cost and raw material cost in comparison to the conventional product of the same level, and can be widely applied to the fields of mines, engineering machinery and the like.

Description

technical field [0001] The invention relates to the production of high-strength and tough steel plates, in particular to a high-strength and tough steel plate with a yield strength of 1000 MPa and a production method thereof. Background technique [0002] At present, the production of high-strength steel plates at home and abroad mainly adopts the method of quenching + tempering (that is, quenching and tempering). For example, WQ960E produced by Wuyang Iron and Steel Co., Ltd. is controlled by C content and alloyed with elements such as Ni, Mo, Nb, Cr, V, Ti, etc., and adopts the method of two-stage controlled rolling + controlled cooling + quenching and tempering. The disadvantage is that the cost of raw materials is very high, and the process is complicated and the manufacturing cost is very high. Another example is the patent No. CN 1840724A of Baosteel Corporation in 2005, "ultra-high-strength steel plate with yield strength above 960 MPa and its manufacturing method" a...

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Problems solved by technology

For example, WQ960E produced by Wuyang Iron and Steel Co., Ltd. is controlled by C content and alloyed with elements such as Ni, Mo, Nb, Cr, V, Ti, etc., and adopts the method of two-stage controlled rolling + controlled cooling + quenching and tempering. The disadvantage is that the cost of raw materials is very high, and the process is complicated and the manufacturing cost is very high

Another example is the patent No. CN 1840724A of Baosteel Corporation in 2005, "ultra-high-strength steel plate with yield strength above 960 MPa and its manufacturing method" and the patent No. CN 1840723A "ultra-high-strength steel plate with yield strength above 1100 MPa and its manufacturing method", All adopt TMCP+ tempering process. The disadvantage of this series of patents is that the cost of steel is high, and it is limited by steel composition and production conditions. The thickness of the finished plate is ≤16mm.

This method uses a more advanced high-density laminar flow cooling method, but its cooling capacity is still low, and the entire production process lacks scientific control of the quality of the original billet, which is relatively ineffective for the production of ultra-high-strength steel plates with a higher degree of alloying. great difficulty

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