Alloyed hot-dip galvanized DH980 steel and preparation method thereof

Abstract

The invention discloses alloyed hot-dip galvanized DH980 steel and a preparation method thereof. The steel comprises 0.16 %-0.23 % of C, 1.5 %-2.5 % of Mn, 0.2 %-0.9 % of Si, 0.02 %-0.9 % of Al, 0.02%-0.70 % of Cr, less than or equal to 0.01 % of P, less than or equal to 0.01 % of S, less than or equal to 0.05 % of Nb, less than or equal to 0.05 % of V, less than or equal to 0.05 % of Ti, and thebalance iron and inevitable impurities, wherein the proportion of (Si+Al) is 0.6 %-1.5 %. The heating temperature of a casting blank is 1150-1300 DEG C, the initial rolling temperature is 1000-1150 DEG C, the final rolling temperature is greater than or equal to 880 DEG C, and the coiling temperature is 500-700 DEG C; the cold rolling reduction rate is 40 %-80 %; and the annealing temperature is760-880 DEG C, the annealing time is 30-300 s, the galvanizing temperature is 450-470 DEG C, the alloying temperature is 470-530 DEG C, and the alloying heat preservation time is 5-60 s. According tothe steel and the method, the tensile strength of a finished steel sheet is 980-1100 MPa, and the high-cycle fatigue ultimate strength is larger than or equal to 370 MPa; and the reaming performance is excellent.

Description

technical field [0001] The invention belongs to the technical field of cold-rolled steel, and relates to a DH980 alloyed hot-dip galvanized automobile steel plate with high strength, high plasticity and excellent fatigue resistance and a preparation method thereof. Background technique [0002] In the automotive industry, higher requirements have been put forward for body weight reduction, emission restrictions, and safety standards. In order to better serve users, the automotive industry has more and more demands for parts with high formability. Traditional dual-phase steels are difficult to meet the requirements of high-drawability complex punching cups, and TRIP steels are widely used due to high alloy content and expensive production costs. DH steel is the English abbreviation of Dual Phase Steels with Improved Formability, which was first mentioned in the VDA 239-100 cold-formed steel plate standard issued by the German Association of Automobile Manufacturers in 2016. ...

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Problems solved by technology

[0003] Patent document CN 106119716 A discloses a 1000MPa grade cold-rolled hot-dip galvanized dual-phase steel with enhanced plasticity and its manufacturing method. Its main chemical components are: C: 0.15%-0.23%, Si: 0.1%-0.5%, Mn: 1.8%~2.3%, P≤0.01%, S≤0.01%, Al: 0.5%~1.0%, Cr: 0.3%~0.6%, Ti: 0.01%~0.04%, the balance is Fe and unavoidable impurities , the patented production process mainly adopts hot-dip galvanizing process, the product has poor plasticity and insufficient fatigue resistance

[0004] Patent document CN 109554616 A discloses a 700MPa hot-rolled TRIP-assisted dual-phase steel and its preparation method. Its main chemical components are: C: 0.14%-0.16%, Si: 0.42%-0.65%, Mn: 1.6% ~1.7%, Al: 0.5%~0.8%, P≤0.014%, S≤0.003%, the production process mainly adopts hot rolling, the strength level is 700MPa, the strength level of this patented product is far from meeting the performance requirements of DH980

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