Chromium-containing high-strength pipeline steel hot-rolled plate

Abstract

The invention discloses Cr bearing high strength pipeline steel hot rolling plate and producing method. Its components weight percentages are 0.30-0.60% Cr, 0.40-0.80% C, 0.10-0.35% Si, 1.80-2.20% Mn, 0.005-0.020% P, not more than 0.003% S, 0.04-0.10% Nb, 0.008-0.030% Ti, 0.15-0.60% Ni, 0.15-0.45% Mo, 0.15-0.30% Cu, the rest Fe and unavoidable impurity, contains 73-87% lower bainite, and the rest island martensite. The producing method includes the following steps: heating up to 1160-1220 degree centigrade; rough rolling at 1010-1150 degree centigrade; finish rolling at 830-950 degree centigrade; water cooling; final cooling at 300-450 degree centigrade; controlling cooling speed at 15-30 degree centigrade per second. The invention can gain the LB main complex phase organization which can make the pipeline steel hot rolling plate yield strength reach 690-825MPa, tensile strength reach 780-960MPa, -20 degree centigrade absorbed-in-fracture energy be not less than 200J, -15 degree centigrade DWTT shearing area be not less than 85%, solve steel anisotropy caused by two phase field rolling, release the demand of large rolling load for the two phase field rolling.

Description

technical field [0001] The invention belongs to a high-strength and high-toughness metal material and a preparation method thereof, and is mainly suitable for manufacturing high-strength pipeline steel hot-rolled flat steel for high-pressure and large-diameter oil and gas pipelines and a production method thereof. technical background [0002] Oil and gas pipelines are an important part of energy construction. With the development of world industry and the development of metallurgical technology, in order to reduce the cost of pipeline construction and operation, and improve the efficiency of oil and natural gas transmission, the transmission pipeline has rapidly developed to the direction of large pipe diameter and high pressure and high density of the transported medium. In the past two years, after X65 and X70 have become the main steel grades of the main pipeline, X80 is also gradually expanding the scope of application. In order to meet the development requirements of m...

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Problems solved by technology

After production, the yield strength of the obtained X100: 437-633MPa, tensile strength: 619-805MPa, the disadvantage is that the yield strength is not enough

"Wide and Thick Plates" Volume 6 No. 5·43· "Development of X80-X100 Grade Pipeline Steel" Lu Yuezhang and Zhou Yuhong, the design composition (weight percentage) of X100 introduced in the article is C: 0.06% ~ 0.08%, Si: 0.20% ~0.40%, Mn: 1.80%~2.00%, Mo: 0.10%~0.30%, Nb: 0.04%~0.06%, Ti: 0.015%~0.025%, Ni: 0.00%~0.25%, Cu: 0.00%~0.25% %, the specific process is not mentioned, the performance yield strength of X100 obtained: round bar sample 739 ~ 755MPa, plate sample 665 ~ 681MPa, tensile strength: round bar sample 792 ~ 820MPa, plate sample 785 ~ 816MPa, its disadvantage is that the yield strength of the plate sample used in the delivery state is not enough

The structure of the steel introduced in the publication number CN1148416A and the title of the invention is "High-strength Trunk Pipe Steel with Low Yield Ratio and Excellent Low-Temperature Toughness" is composed of martensite / bainite and 20% to 90% ferrite Its rolling process is that the cumulative rolling reduction ratio in the two-phase area is 10% to 70%, and the hot rolling termination temperature is 650 to 800°C. The disadvantage is that the rolling force of the rolling mill is relatively high, and it is difficult for general rolling mills to Adaptation, and rolling in the two-phase region, there is anisotropy in performance

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