600 MPa-grade low-manganese nickel-containing alloying hot galvanizing dual-phase steel with enhanced broaching performance and production method thereof

Abstract

The invention discloses 600 MPa-grade low-manganese nickel-containing alloying hot galvanizing dual-phase steel with enhanced broaching performance and a production method thereof, and belongs to the technical field of hot galvanizing automobile high-strength steel. The dual-phase steel comprises the following main chemical elements in percentage by mass: 0.05%-0.09% of C, 0.05%-0.20% of Si, 0.9%-1.5% of Mn, 0.15%-0.45% of Cr, 0.10%-0.50% of Mo, 0.01%-0.05% of Ti, 0.01%-0.08% of Als, 0.0005%-0.0065% of B, 0.01%-0.05% of Nb, 0.05%-0.80% of Cu, 0.05%-0.90% of Ni, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, less than or equal to 0.005 percent of N and the balance of Fe and inevitable impurities. The produced 600 MPa-grade alloyed hot galvanizing dual-phase steel with the hole expansion rate of 41.5%-69.0% is suitable for complex automobile parts with high requirements on flanging, hole expansion and forming performance.

Description

technical field [0001] The invention belongs to the technical field of hot-dip galvanized high-strength steel for automobiles, and more specifically 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 auto industry has been showing a good trend of rapid development. Since 2009, China's auto production and sales have ranked first in the world for consecutive years. 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, realize the lightweight of the whole vehicle, and achieve the effect of energy saving and emission reduction. [0003] With the higher and higher r...

AI Technical Summary

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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