High-strength cold-rolled hot-galvanized dual-phase steel plate and manufacture method thereof

Abstract

The invention discloses a high-strength cold-rolled hot-galvanized dual-phase steel plate, characterized in that components, in mass percentage, are: 0.03% to 0.15% of C, less than or equal to 0.15% of Si, 1.00% to 1.75% of Mn, less than or equal to 0.015% of P, less than or equal to 0.012% of S, 0.02% to 0.15% of Al, 0.35% to 0.75% of Cr, 0.02% to 0.15% of Cu, 0.010% to 0.035% of Ti, less than or equal to 0.005% of N, in addition meeting the requirement that the total percentage of Mn, 1.29Cr and 0.46Cu is not less than 1.5% and not more than 2.5%, and the balance being Fe and inevitable impurities. The manufacture method comprises converter smelting, secondary refining, continuous casting, hot continuous rolling, cold acid continuous rolling, annealing galvanizing and hot dipping, wherein a galvanized substrate with a reasonable organization and composition and an excellent plate shape is obtained through controlled rolling and controlled cooling while rolling; and through employing a micro-slowly cooling way for heating from an end segment to an isothermal segment and a secondary fast cooling way for a fast cooling segment during continuous annealing galvanizing, the cold-rolled hot-galvanized dual-phase steel plate is obtained, wherein the steel plate is advantageous by having a tensile strength between 490 to 700 MPa, well-matched strength and ductility, an excellent coating performance, and a thickness between 0.5 to 2.5 mm, and can be used as an automobile cover component, an inner plate, a structural component, etc.

Description

technical field [0001] The invention belongs to the technical field of cold-rolled high-strength thin plates for automobiles, and provides a high-strength cold-rolled hot-dip galvanized dual-phase steel and a manufacturing method thereof. Background technique [0002] In recent years, with the continuous improvement of people's requirements for car crash safety and corrosion resistance, steel sheets for automobiles have developed towards high strength and full coating, which has prompted high-strength IF steels, bake-hardening steels, phase-transformation-induced plasticity steels and double-layer steels. The application of hot-dip galvanized high-strength steel such as phase steel in automobile body. At the same time, in order to reduce the greenhouse effect and protect the earth's environment, strengthen the control of CO 2 The limitation of emissions, which contributes to the lightweight of automobile bodies with low fuel consumption, has become an important research top...

AI Technical Summary

Problems solved by technology

Although it is easy to obtain a typical dual-phase structure, it is very difficult to maintain 20-100s in the range of 454-493°C on the existing continuous hot-dip galvanizing production line, and the present invention does not take into account the lower heating and holding temperature, and it is difficult to eliminate Mn When the Mn content is large (such as the Mn content of the steel in the example reaches 1.81%), the banded structure formed mainly by cementite, pearlite, and bainite

At the same time, the invention does not mention how to produce cold-rolled substrates with suitable microstructure and good shape

[0006] The steel described in CA2564050A1 needs to add Mo, B, Ca, Cr, Ni, Nb, V, Ti and many other elements at the same time, and obtain a cold-rolled hot-dip galvanized dual-phase steel with a tensile strength of 440-780MPa through the hot-dip galvanizing process. More elements are added, which increases the difficulty of steelmaking and increases the manufacturing cost

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