Method for producing ultrathin hot-rolled coils from sheet billets by continuous casting and rolling
The invention discloses a method for producing ultrathin hot-rolled coils from sheet billets by continuous casting and rolling. The method includes the technologic steps of (1) steelmaking process, (2) continuous casting process, (3) heating process, (4) hot rolling process and (5) cooling and coiling process. The continuous casting process includes drawing steel balls into continuous casting billets by means of continuous casting, wherein casting speed is controlled to be 4.5-4.7 meters/minute, feeding-to-furnace temperature is within a range from 935 DEG C to 960 DEG C, and thickness and width of the casting billets are controlled to be 70mm and 1260mm respectively. The heating process includes heating the continuous casting billets by a heating furnace with a three-step furnace temperature control function. The hot rolling process includes producing the heated continuous casting billets into ultrathin hot-rolled sheets via a roughing mill and a finishing mill, and controlling finishing temperature as 870 DEG C. The cooling and rolling process includes after the ultrathin hot-rolled sheets are subjected to laminar cooling, coiling at the temperature of 670 DEG C by means of positioning control through a side guide of a coiling machine so as to obtain the ultrathin hot-rolled coils. By reasonable control on rolling temperature, pressing mechanism and stable threading technology, the 1.0mm ultrathin hot-rolled coils are rolled stably in a single piece manner in the continuous casting and rolling flow of the sheet billets, and stable batch production of 1.00 ultrathin strip steel is realized. 1. Continuous casting and rolling process for producing ultra-thin hot-rolled coils, characterized in that it comprises the following process steps: 1) steel-making process: the smelting of the converter, the refining and alloying the same outside the furnace, control of the chemical components and the weight percent is:C 0.18-0.22%, Mn 0.20-0.40%, Si [...] 0.15%, the S [...] 0.012%, P [...] 0.025%, Als 0.015-0.035%, B 0.0009-0.0030%, the rest are Fe and unavoidable impurities; 2) continuous casting process: into the above-mentioned steel continuous casting billet by continuous casting; the casting blank control the pull rate is 4.5-4.7 meters/minute, the temperature of the furnace the 935-960 [...] , casting for controlling thickness of 70 mm, the width is 1260 mm; 3) heating procedure: the three sections states the continuous casting semifinished product the heating furnace temperature control of the heating furnace; furnace control a section 1290 ±10 °C, two sections of furnace temperature 1300 ±10 °C, three sections of the furnace temperature is 1300 ±10 °C, heat insulation section 1260 ±10 °C; slab insulation time 24.5-26 minutes; the discharging temperature is 1250 ±10 °C; outlet temperature of roughing the 1080-1090 [...] , finish rolling inlet temperature the 1035-1050 [...] ; 4) hot rolling: continuous casting billet after heating through the coarse rolling mill and finishing mill rolling into the ultra-thin hot rolled plate, controlling the finishing temperature in the 870 [...] ; 5) cooling coiling process: ultra-thin hot-rolled plate after cooling through the laminar flow, the use of side guide position control, the 670 the carry on coiling [...] , ultra-thin hot-rolled coils can be obtained. 2. Continuous casting and rolling process for producing ultra-thin hot-rolled coils according to Claim 1, characterized in that the heating in the heat storage type heating furnace. 3. Continuous casting and rolling process for producing ultra-thin hot-rolled coils according to Claim 1, characterized in that the hot-rolling process for the control of the process in the: control enters the rolling mill with the rolling mill central line of the center line of the slab the deviation of ± 5 mm within; The rough rolling high-speed belt 45%, finishing strip threading speed is 10.6-11.4m/s, tailings speed setting for 10.5m/s, rolling speed is set to the largest 14m/s; in the rolling process, the deceleration rate FDTC -0.005m/s2. 4. Continuous casting and rolling process for producing ultra-thin hot-rolled coils according to Claim 1, characterized in that in the cooling process, when the strip head through the laminar flow cooling, to be the head end of the sheet after the injection of the beginning of the laminar flow cooling water. 5. -4 the thin slab continuous casting and continuous rolling of the method of producing ultra-thin hot-rolled coils according to Claim 1, characterized in that said ultra-thin hot-rolled coils of ≥ 25% elongation, yield strength 350-400MPa, tensile strength 470-530MPa.