A kind of 600mpa grade low manganese nickel-containing alloyed hot-dip galvanized dual-phase steel with enhanced hole expansion performance and production method thereof

Abstract

The invention discloses a 600MPa grade low-manganese-nickel alloyed hot-dip galvanized dual-phase steel with enhanced hole expansion performance and a production method thereof, and belongs to the technical field of hot-dip galvanized automobile high-strength steel. The main chemical element composition and mass percentage of dual-phase steel are: C: 0.05-0.09%, Si: 0.05-0.20%, Mn: 0.9-1.5%, Cr: 0.15-0.45%, Mo: 0.10-0.50%, Ti: 0.01~0.05%, Als: 0.01~0.08%, B: 0.0005~0.0065%, Nb: 0.01~0.05%, Cu: 0.05~0.80%, Ni: 0.05~0.90%, P≤0.020%, S≤0.010%, N≤0.005%, the balance is Fe and inevitable impurities. The 600MPa grade alloyed hot-dip galvanized dual-phase steel with a hole expansion rate of 41.5-69.0% is produced, which is suitable for complex auto parts with high requirements for flanging and hole expansion.

Description

technical field [0001] The invention belongs to the technical field of hot-dip galvanized high-strength steel for automobiles, and more particularly relates to a 600MPa grade low-manganese-nickel-containing alloyed hot-dip galvanized dual-phase steel with enhanced hole expansion performance and a production method thereof. Background technique [0002] Since the 21st century, China's automobile industry has been showing a good momentum of rapid development. Since 2009, China's automobile production and sales have ranked first in the world. However, as an important energy-consuming industry, the automobile industry has become one of the most important sources of air pollution in my country. Therefore, the application of advanced high-strength steel is the most effective way to improve the safety performance of automobiles and realize the lightweight of the whole vehicle to achieve the effect of energy saving and emission reduction. [0003] With the increasingly high require...

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Problems solved by technology

[0014] Aiming at the problem of poor flanging and hole expansion forming performance of 600MPa grade alloyed hot-dip galvanized dual-phase steel products in the prior art, the present invention provides a 600MPa grade low-manganese nickel-containing alloyed hot-dip galvanized dual-phase steel with enhanced hole expansion performance Steel, on the basis of traditional 600MPa alloyed hot-dip galvanized dual-phase steel, adopts low-carbon-low-silicon-low-manganese chemical composition design of titanium-boron-niobium-copper-nickel microalloying, low-temperature crimping process, high-temperature slow cooling process, The process of hot-dip galvanizing process is precisely controlled according to the thickness level, with a reasonable process flow: molten iron pretreatment→converter smelting→alloy fine-tuning station→LF furnace refining→continuous casting steelmaking→hot rolling→pickling cold rolling→continuous annealing→heating Dip galvanizing→alloying→overaging→finishing to eliminate the band structure and improve the uniformity of the structure and performance of the steel plate; refine the hard phase grains to comprehensively improve the strength and toughness of the steel; refine and strengthen the ferrite , reduce the strength difference between the soft phase ferrite and the hard phase martensite; introduce an appropriate amount of intermediate strength granular Bainite that acts as a buffer transition between the soft phase ferrite and the hard phase martensite 600MPa-grade alloyed hot-dip galvanized dual-phase steel with a product hole expansion rate of 41.5-69%. At the same time, the surface coating quality of the steel is good, and it is suitable for complex forming automobiles with high requirements for flanging and hole expansion. Parts

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