Thick steel plate and manufacturing method thereof

Abstract

The invention discloses a thick steel plate and a manufacturing method thereof, and belongs to the field of ferrous metallurgy. The method comprises the following steps of molten iron KR pre-desulfuration, converter smelting, LF refining, RH vacuum treatment, wire feeding, flexible stirring, plate blank continuous casting, plate blank reheating, rough rolling, intermediate blank temperature holding cooling, precision rolling, ACC quick cooling, steel plate straightening and stacking slow cooling, wherein in the plate blank reheating stage, the temperature is 1120-1220 DEG C, and the in-furnacetime is longer than or equal to 1.0 min / mm; in the rough rolling stage, the temperature is 1000-1080 DEG C, and the thickness of an intermediate blank after rolling is larger than 2.5 times that of asteel plate; in the precision rolling stage, the temperature is lower than or equal to 900 DEG C, the finish rolling temperature is 780-820 DEG C, and the total compression ratio in the stage is larger than or equal to 60%; in the cooling stage, the finish cooling temperature is 300-400 DEG C, and the cooling rate is 10+ / -5 DEG C / s. The steel plate manufactured through the method comprises the following chemical components of, by mass percent, 0.06-0.09% of C, 0.10-0.30% of Si, 1.40-1.70% of Mn, 0.020-0.060% of Al, 0.03-0.05% of Nb, 0-0.020% of Ti, 0-0.30% of Cr, 0-0.016% of P, 0-0.005% of S,0-0.080% of N and the balance Fe and inevitable impurity elements, the carbon equivalent Ceq is equal to [C+Mn / 6+(Cr+Mo+V) / 5+(Cu+Ni) / 15] and smaller than or equal to 0.42%, the welding crack sensitivity index CEpcm is equal to [C+Si / 30+(Mn+Cu+Cr) / 20+Ni / 60+Mo / 15+V / 10+5B] and smaller than or equal to 0.20%, and the applicable thickness of the steel plate is 40-70 mm.

Description

technical field [0001] The invention belongs to the field of iron and steel metallurgy, in particular to a thick gauge steel plate and a manufacturing method thereof. Background technique [0002] With the continuous progress of infrastructure construction in my country and other countries in the world, especially the continuous progress of bridge construction, the design load of bridges has increased correspondingly, and the thickness, strength and toughness of pile pipes have also increased accordingly. High strength (yield strength > 460MPa) is high The demand for structural steel with toughness (impact energy at -20°C > 100J) is increasing, and the demand for steel plate materials with easy-to-weld properties is also increasing. [0003] In the past, steel plates with similar specifications and strengths were often delivered in a quenched and tempered state. On the one hand, the alloy content of the quenched and tempered steel plate is relatively high, and alloy ele...

AI Technical Summary

Problems solved by technology

[0006] Technical problem to be solved: the purpose of this invention is to solve the problems of high production cost, small application range, low pass rate and poor performance uniformity of existing similar steel plates, and develop a thick gauge steel plate and its manufacturing method. The manufacturing method can reduce the manufacturing cost of high-strength extra-thick steel plate, improve the pass rate and control the uniformity of performance

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