Method of producing thin-gauge hot rolled DP600 steel based on CSP flow

Abstract

The invention discloses a method of producing thin-gauge hot rolled DP600 steel based on a CSP flow. The method comprises the following steps that (1) components of molten iron are adjusted; (2) sheetbillet continuous casting is carried out with the casting billet thickness being controlled at 52-55 mm and the casting speed being controlled at 3.8-4.2 m / min; (3) conventional soaking is carried out with the tapping temperature being controlled at 1190-1210 DEG C and the soaking time being controlled at 25-35 min; (4) scale removal with high pressure water is carried out; (5) seven passes of finish rolling are carried out, wherein the finishing temperature is 790-820 DEG C and the rolling speed of a final stand is 6.6-10.2 m / s; (6) two-stage type cooling and winding are carried out, whereinwater cooling to 670-690 DEG C and then air cooling for 4.0-6.6 s are carried out in the first stage, and water cooling to 100-150 DEG C is carried out in the second stage; and (7) leveling is carried out. The thin-gauge hot rolled DP600 steel is stable in performance, has the characteristics of low cost, high strength, thin gauge and low yield ratio, can meet the quality requirements on cold-rolled products, and has great significance in promoting the progress of replacing cold rolling with hot rolling in the automobile industry.

Description

technical field [0001] The invention relates to a hot-rolled DP600 steel, in particular to a method for producing thin gauge hot-rolled DP600 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-performance automotive steel is an effective means to reduce weight, save energy and improve safety. Duplex steel, referred to as DP steel, is an advanced high-strength steel composed of ferrite and martensite two-phase structure. Because of its low yield ratio, high initial work hardening rate, good strong-plastic matching and bake hardening performance, etc., It can meet the application requirements of various structural parts, reinforcement parts and anti-collision parts of automobiles, and has become the most widely used and most diverse automobile structural steel. [0003] According to the production met...

AI Technical Summary

Problems solved by technology

The above two documents and the existing CSP process produce thick-gauge hot-rolled dual-phase steel, which cannot meet the needs of the automotive industry for thin-gauge hot-rolled dual-phase steel that "replaces heat with cold".

[0007] In the process of thin slab continuous casting and rolling to produce thin specifications, especially hot-rolled DP600 steel with a thickness specification below 1.5mm, affected by the short length of the laminar cooling zone and the fast rolling speed of the final stand, the water cooling time and air cooling time Short makes the transformation of ferrite insufficient, the content of martensite is too high, even bainite and pearlite appear, and the yield ratio of the product is high

At the same time, due to the low-temperature coiling, the thin-gauge hot-rolled DP600 steel has a poor shape and 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 DP600 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 stable matching of chemical composition, process window, microstructure and shape quality for thin gauge (thickness ≤ 2.0mm) hot-rolled DP600 steel, 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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