A kind of cold-rolled high-strength light steel and its preparation method

Abstract

The invention discloses a cold-rolled high-strength light steel and a preparation method thereof. Contained in steel, C: 0.3% to 0.6%, Si: 0.1% to 0.3%, Mn: 1.0% to 4.0%, P: 0.09% to 0.18%, S≤0.03%, Al: 3.0% to 6.0%, B : 0.0004% ~ 0.0012%, the rest is Fe and unavoidable impurities. The starting rolling temperature is 1000-1150℃, the final rolling temperature is 850-1000℃, the cooling method adopts laminar flow cooling method, the coiling temperature is 500-700℃; the cold rolling reduction rate is 40%-80%; the continuous annealing temperature is 800-900℃ , the annealing time is 120-400s, the cooling rate is 15-60°C / s, the cooling temperature is 20-200°C, the tempering temperature is 200-350°C, the tempering time is 300-800s, and finally the cooling rate is 10-30°C / s to room temperature. The tensile strength of the finished steel plate is greater than 980MPa, the elongation is greater than 12%, and the density is (7.30~7.55)×10 3 kg / m 3 .

Description

technical field [0001] The invention belongs to the field of steel manufacturing for automobiles, in particular to a high-strength and light-weight cold-rolled steel above 980 MPa. Background technique [0002] At present, the development trend of the automobile industry is energy saving, weight reduction, environmental protection and safety improvement. The use of high-strength automobile steel can meet the needs of the automobile industry for weight reduction and safety improvement. However, the currently developed high-strength steel for automobiles reduces the weight-saving effect of automobiles due to their high density. Therefore, the development of lightweight phase transformation induced plasticity steel with high strength and plasticity has attracted the attention of major steel companies and automobile manufacturers. [0003] Patent CN103370434B discloses an austenitic light-weight high-strength steel plate with high yield ratio and ductility, which is designed wi...

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Problems solved by technology

[0003] Patent CN103370434B discloses an austenitic light-weight high-strength steel plate with high yield ratio and ductility, which is designed with high manganese composition, and the manganese content reaches 10% to 15%, which leads to high alloy cost and limited application. limit

[0004] Patent CN106086658B discloses a high-strength, medium-carbon, chromium-containing, low-manganese light steel and its preparation method. It adopts low-manganese and medium-carbon composition design, and its tensile strength only reaches 780MPa, which cannot meet the needs of automobile manufacturers for higher strength cold steel. Requirements for rolling light steel

[0005] Patent CN106498307B discloses a high-strength, high-toughness light steel with good cold working performance at 780MPa level and its manufacturing method. Its tensile strength only reaches 780MPa level, which is difficult to meet the requirements of automobile manufacturers for ultra-high-strength cold-rolled light-weight steel

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