High strength IF steel with excellent corrosion resistance and manufacturing method thereof

Abstract

The invention discloses high strength IF steel with excellent corrosion resistance. The high strength IF steel comprises the following chemical elements in percentage by mass: greater than 0 but lessthan or equal to 0.009% of C, greater than 0 but less than or equal to 0.01% of Si, 0.2-0.8% of Mn, 0.02-0.08% of P, 0.005-0.025% of Nb, 0.005-0.025% of Ti, 0.0001-0.001% of B, 0.01-0.09% of Al, lessthan or equal to 0.005% of N, less than or equal to 0.015% of S and the balance of Fe and other inevitable impurities. The invention also discloses a manufacturing method of the high strength IF steelcorrespondingly. The manufacturing method comprises the following steps: smelting and casting; hot rolling; and annealing. The tensile strength of the high strength IF steel disclosed by the invention is greater than or equal to 360MPa, and the surface potential representing the corrosion resisting property of the steel is greater than or equal to -410mV.

Description

technical field [0001] The invention relates to a steel grade and a manufacturing method thereof, in particular to a high-strength IF steel and a manufacturing method thereof. Background technique [0002] Due to the advantages of good coating performance, excellent stamping performance and relatively low price, cold-rolled sheets are widely used in many automobile manufacturers. Therefore, auto parts such as automobile outer and inner panels use cold-rolled sheets. Among them, automobile outer panels are high-end output products of large steel production plants. Automobile outer panels such as roof covers, front and rear doors, and fenders, due to complex deformation and high appearance requirements, have great impact on stamping performance and coating performance. The requirements of the aspect are much stricter than those of the inner panels of automobiles, so interstitial atom-free steel (IF steel) is mostly used. IF steel is an ultra-low carbon, ultra-deep drawing ste...

AI Technical Summary

Problems solved by technology

At the same time, with the increase in demand for emission reduction and cost reduction of automobiles, high-strength cold-rolled IF steel products are applied to automobile outer panels, but the problem in the current prior art is that the corrosion resistance of high-strength cold-rolled sheets is often It is lower than normal cold-rolled sheet, which is caused by the chemical composition and production process of high-strength cold-rolled sheet

The surface corrosion of steel products has always been an important quality issue that steel manufacturers and car users care about. On the one hand, corrosion will affect the smooth production of steel factories, and on the other hand, it will also have a great impact on the use of users. It will even directly cause users to be unable to use normally, which will cause users to complain and reduce the market share of cold-rolled steel sheets for steel production plants

At present, although the outer panels of automobiles using high-strength cold-rolled IF steel meet the needs of users for high strength, due to easy corrosion, steel mills and users often need to invest more manpower and material resources to avoid corrosion in large quantities. , and it is unavoidable to avoid the occurrence of batch corrosion in the harsh environment of high temperature and high humidity, which will cause quality objections.

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