800MPa-grade hot-rolling transformation induced plasticity steel plate and its manufacturing method

Abstract

The invention provides a 800MPa-grade hot-rolling transformation induced plasticity steel plate and its manufacturing method. The transformation induced plasticity steel plate and its manufacturing method comprises 0.05-0.3% of C, 0.5% or less of Si, 0.6-3.0% of Mn, 0.01-0.08% of Als, 0.05-0.1% of P, 0.01-0.1% of Nb, below 0.005% of S, and the balance Fe. The manufacturing method comprises the steps of slab continuous casting, direct heat charging, heating, rough rolling, precision rolling, laminar cooling and reeling, wherein the thickness of the continuous casting slab is 135-200mm, the heat charging temperature is not less than 400DEG C, the heating temperature is 1180-1220DEG C, two-phase control rolling is carried out at a maintained temperature for 1-3h, the rolling temperature is a recrystallization region is 1050-1100DEG C, the rolling temperature in a non-recrystallization region is 900-940DEG C, the finishing temperature is 820-880DEG C, the reduction rate is greater than 70%, the laminar cooling speed after rolling is 20-40DEG C / s, the reeling temperature is 350-500DEG C, and the finished product thickness is 3-10mm.

Description

technical field [0001] The invention belongs to the technical field of iron and steel materials, and in particular relates to a hot-rolled phase-change-induced plasticity steel plate for automobile manufacturing with a tensile strength of 800 MPa and a manufacturing method thereof. Background technique [0002] With the development of industry, considering the increasingly serious energy shortage and environmental pollution, the requirements for the comprehensive mechanical properties of structural materials are getting higher and higher. While having high strength, matching good plastic properties are also widely required. [0003] As a kind of steel mainly used in the automobile industry, phase transformation induced plasticity steel has good strength-plasticity matching. Compared with traditional automobile steel, its strength and plasticity advantages are obvious. If it can be widely used in the field of automobile manufacturing, It can greatly reduce the weight of the ...

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Problems solved by technology

[0004] Patent No. US6797078 proposes a 700MPa grade hot-rolled phase-transition-induced plasticity steel plate and its manufacturing method. It adopts the composition design of replacing Si with Al, and the surface quality of the steel plate is improved, but the cooling process after rolling is relatively complicated. At the same time, the composition It also contains Cr and a large amount of C and Mn elements, which brings difficulties to smelting and welding, and increases the cost

The transformation-induced plasticity steel mentioned in the patent No. CN101191174A also adopts the composition route of replacing Si with Al, but its composition does not contain Cr element, but a small amount of Nb is added. The performance of the steel plate is excellent, but its rolled Finally, three-stage cooling is adopted, and the cooling process is complicated

The patent No. JP2003321738A proposes a hot-rolled phase transformation induced plastic steel plate and its manufacturing method. Its composition contains a large amount of Si and Mo elements, and the surface quality of the steel plate is not good and the cost is high.

The steel plate mentioned in the patent No. EP295500A1 has good formability and low cost, but there is also the problem that the high Si content affects the surface quality

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