400 MPa grade hot dip galvanized high-strength IF steel for car front fender and manufacturing method of high-strength IF steel

Abstract

The invention discloses a 400 MPa grade hot dip galvanized high-strength IF steel for a car front fender and a manufacturing method of the high-strength IF steel. According to the method, P, Si and Mnelements are appropriately added on an IF steel base body to perform solid solution strengthening to ensure the strength, Ti alloy elements are added to eliminate interstitial atoms and achieve precipitation strengthening, an appropriate amount of B element is added to inhibit segregation of P at the grain boundary position, a high elongation after fracture and a low yield ratio are ensured, andmeanwhile, the tensile strength is improved; in combination with the capacity characteristics of production equipment, through smelting, a 2250 mm hot rolling mill, a pickling continuous rolling unitand a continuous annealing process, the finished product yield strength 180-240 MPa, the tensile strength 340-400 MPa, the elongation after fracture >= 34% (tensile test: L0=80 mm, b=20 mm), n value >= 0.18, and r value >= 1.7 are achieved, and a low yield ratio and a good punching performance are ensured.

Description

technical field [0001] The invention relates to the technical field of high-strength steel for automobiles, in particular to a hot-dip galvanized high-strength IF steel for front fenders of 400MPa class cars and a manufacturing method thereof. Background technique [0002] With the continuous development of modern industrial technology, saving energy and protecting the environment has become a major issue of concern to the whole society, and the automobile industry is no exception. Therefore, in the structural performance of modern automobiles, reducing weight and consumption, reducing environmental pollution and improving safety have become research hotspots. [0003] Because hot-dip galvanized ferroalloy products have good welding performance, coating performance and corrosion resistance, they are widely used in the outer panels of high-end automobiles. The existing traditional difficult stamping parts are basically made of ordinary IF steel. However, as the weight reduct...

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Problems solved by technology

[0005] The patent application with the publication number CN103710617A provides a 340MPa grade hot-dip galvanized iron alloy high-strength IF steel. In its chemical composition, the Nb content is 0.01-0.025%, and the Ti content is 0.005-0.015%. The addition of Nb element also increases the manufacturing cost

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