IF cold rolling steel with the tensile strength larger than or equal to 440 MPa and production method

Abstract

The invention discloses IF cold rolling steel with the tensile strength larger than or equal to 440 MPa. The steel comprises, by weight percent, 0.001 to 0.003% of C, 0.07 to 0.10% of Si, 0.70 to 0.90% of Mn, 0.020 to 0.045% of Als, 0.060 to 0.075% of P, not larger than 0.010% of S, 0.0005 to 0.0013% of B, not larger than 0.02% of Nb, and not larger than 0.03% of Ti. A production process comprisesthe steps of conventional smelting and casting to form a blank; rough rolling and finish rolling; segmented cooling to the coiling temperature; reeling a hot rolling plate; acid picking; cold rolling; and reeling a cold rolling plate. On the premise of ensuring the use mechanics of the steel plate, the mechanical property is small in fluctuation, the cold rolling rate is improved to not lower than 20%, the rolling speed can be stabilized to above 500 m / min, the thickness precision can be controlled to be within 15 micrometers, the strip steel rolling process is stable, the strip steel thickness is reduced, the fluctuation is stable, and the plate shape is greatly improved.

Description

technical field [0001] The invention relates to a cold-rolled alloy steel and a production method, which exactly belong to IF cold-rolled steel and a production method. Background technique [0002] The automobile industry is a pillar industry in industrially developed countries, and it is also the largest user of steel enterprises. Under the requirements of energy saving, environmental protection, safety and sustainable development, automobile manufacturers have put forward higher requirements for the quality of automobile steel. High-strength IF has higher performance and better deep drawing performance and has more performance, but because high-strength IF steel adds more alloying elements such as Nb and Ti to improve strength, but more Nb and Ti alloys The addition of elements will lead to problems such as the precipitation of Nb and Ti during the hot rolling process, resulting in large fluctuations in strength. The plate shape is poor, resulting in large fluctuations i...

AI Technical Summary

Problems solved by technology

The commonality of the above-mentioned documents is that the strength and mechanical properties of hot-rolled incoming materials fluctuate greatly, and at the same time, the shape of the plate is not good; , the rolling speed is generally below 400m / min, which seriously restricts the production efficiency and product quality

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