High-formability high-weatherability ultrathin hot-rolled steel plate and CSP (compact strip production) technology thereof

Abstract

The invention discloses a high-formability high-weatherability ultrathin hot-rolled steel plate and a CSP (compact strip production) technology thereof. The steel plate comprises the following compositions in percent by weight: 0.035-0.065% of C, 0.15-0.3% of Si, 1.3-1.6% of Mn, 0.12-0.2% of Cu, 0.2-0.6% of Cr, 0.1-0.2% of Ni, 0.1-0.13% of Ti, 0.1-0.2% of Mo, 0.025-0.045% of Als, 0-0.018% of P, 0-0.005% of S, 0-0.006% of N, and the balance Fe and unavoidable impurities. According to the production technology, the P content of discharged steel smelted in a converter is controlled at 0-0.012%, the crystallizer heat flux is controlled at 2.45-2.55 mw / m<2>, the specific water flow for continuous-casting secondary cooling water is controlled to be 1.77-1.83 L / Kg, a cast-on continuous casting slab is controlled to have the thickness of 65-75 mm and has the thickness of 55-60 mm after being frequently pressed by a liquid core, the discharging temperature of the casting slab is controlled to be 1230-1250 DEG C, and the final rolling temperature is controlled to be 880-920 DEG C. Reeling is performed after laminar-flow cooling is performed, a head-part step cooling manner is employed, and rapid cooling is performed after the casting slab is reeled, unloaded and cooled to 280-320 DEG C at a cooling speed of 10 DEG C / s or less. The prepared thin steel plate possesses high formability while stably obtaining high strength and high weatherability.

Description

technical field [0001] The invention relates to metallurgical technology, in particular to a hot-rolled steel plate with high profile, high weather resistance and ultra-thin specification and its CSP production process. Background technique [0002] WISCO's CSP production line is the latest generation of thin slab continuous casting and rolling production line. It was hot-tested in March 2009. The production line includes two 150-ton converters, two LF refining furnaces, one RH refining furnace, two-strand thin slab continuous casting line, Tunnel furnace and seven-stand hot rolling mill. The maximum slab width produced by the casting machine is 1680mm, and the thickness is 70mm and 90mm. The designed working speed of the machine can reach 5-6m / min. The annual design production capacity of hot-rolled strip steel of the entire production line is 2.5 million tons, of which 542,000 tons are for hot-rolled pickling and galvanized coils, 978,000 tons are raw silicon steel coils...

AI Technical Summary

Problems solved by technology

When the high-strength thin material is produced in batches on the CSP production line, due to the special shape of the funnel-shaped mold of the CSP continuous casting machine and the high content of alloy elements in the high-strength steel, the formability of the product needs to be improved; rolling thin steel plates requires liquid core pressing Under normal circumstances, the billet shell is easy to deform, and the risk of steel breakout is high, and the steel breakout rate reaches 40% at the highest; in addition, in the field of high-strength thinning, the forming of many formed parts is relatively complicated, and some require secondary forming or pickling after forming, while The high-strength thin materials produced in the early stage of CSP have problems such as secondary molding cracking or pickling cracking, which seriously restricts the development and promotion of such high value-added products in the CSP production line.

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