Method for producing thin hot-rolled DP1180 steel on basis of CSP (Cast Steel Plate) procedures

Abstract

The invention discloses a method for producing thin hot-rolled DP1180 steel on the basis of CSP (Cast Steel Plate) procedures. The method comprises the following steps: 1) adjusting the components ofmolten iron; 2) performing continuous casting on a thin plate blank, and controlling the thickness of a cast blank to be 55-65mm, wherein the blank drawing speed is 3.5-3.9m / minute; 3) performing common uniform heating, controlling the tapping temperature to be 1220-1250 DEG C, wherein the uniform heating time is 25-35 minutes; 4) performing high-pressure water descaling; 5) performing seven timesof fine rolling, wherein the final rolling temperature is 800-830 DEG C, and the rolling speed of a tail rack is 6.8-10.2m / s; 6) performing two-section type cooling and coiling, performing water cooling to 660-680 DEG C at a first section, performing air cooling for 3.6-4.7 seconds, and further performing water cooling to 150-250 DEG C at a second section; 7) performing flattening. The method isshort in manufacturing procedure, stable in product property and high in plate shape quality, has the characteristics of being low in cost, high in strength, thin in specification and low in yield ratio and has great significances on achieving lightening of automobiles and promoting 'replacing cold with heat' of the automobile industry, the thickness precision can be controlled within + / -30mum, and quality requirements of cold rolled products can be met.

Description

technical field [0001] The invention relates to a hot-rolled DP1180 steel, in particular to a method for producing thin gauge hot-rolled DP1180 steel based on a CSP process. Background technique [0002] With the depletion of energy and the deterioration of the ecological environment, the lightweight of automobiles has attracted more and more attention. The use of high-strength automotive steel is an effective means to reduce weight, save energy and improve safety. In the Ultra Light Steel Body-Advanced Concept Vehicle (ULSAB-AVC) program of the World Iron and Steel Institute, high-strength steel accounts for 97% of the materials used, of which advanced high-strength steel accounts for more than 80%. However, as the strength continues to increase, the formability of the material will become worse and worse, especially for high-strength steel above 1180MPa, there will be problems such as cracking, springback, and parts that cannot meet the precision requirements during the f...

AI Technical Summary

Problems solved by technology

However, in the process of producing thin-gauge hot-rolled DP1180 steel (especially with a thickness below 1.5mm), affected by the short length of the laminar flow cooling zone and the fast rolling speed of the last stand, the short water cooling time and air cooling time make ferrite Insufficient body transformation, too high martensite content and even bainite and pearlite, the product has a high yield ratio

In addition, due to low-temperature coiling, the shape of the thin-gauge hot-rolled DP1180 steel is poor, and it must be leveled, and the steel plate undergoes work hardening after leveling, resulting in a further increase in yield strength and yield ratio, resulting in the formation of hot-rolled DP1180 steel. Poor performance, increased wear and springback on the die during part stamping

Therefore, under the existing thin slab continuous casting and rolling process conditions, it is difficult to achieve the stability of chemical composition, process window, microstructure and shape quality for hot rolling DP1180 steel with thin specifications (especially thickness specifications below 1.5mm) match

So far, there is no precedent at home and abroad for the production of hot-rolled dual-phase steel DP1180 by continuous casting and rolling of thin slabs, which restricts the industrial production of this type of steel and the process of "replacing cold with heat" in the automotive industry

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