A kind of aluminum-silicon coated steel plate for hot pressing and its manufacturing method

Abstract

The invention discloses an aluminum-silicon plated steel plate for hot-press molding and its fabrication method. The steel plate is plated with an aluminum-silicon plating on its surface, wherein the plating contains (by weight percentage) aluminum 96-98, silicon 1.3-3.8 and rare earth 0.1-0.3, thickness of an alloy layer is smaller than or equal to 5 Mum, and silicon content in the alloy layer is controlled at 3-6 wt%. The fabrication method comprises pre-oxidizing a steel plate via an NOF, wherein reduction furnace atmosphere contains H2 20-50 vol% and N2 in balance, dew point in the furnace is controlled at (-20)-(-60) DEG C., annealing temperature is 800-850 DEG C., temperature of a plating solution is 680-750 DEG C., temperature of the steel plate, while being placed in an aluminum pot, is 650-750 DEG C., and immersion plating time is 2-5 s; taking the steel plate out of the aluminum pot, and rapidly cooling at speed of no smaller than 120 DEG C. / s until solidifying point of aluminum-silicon alloy is achieved; and cooling to 420-480 DEG C. at speed of 30-100 DEG C. / s, and performing overaging annealing at 350-450 DEG C. for 10-300 s.

Description

Technical field [0001] The invention belongs to the field of continuous hot dip coating of strip steel, and particularly relates to an aluminized silicon steel sheet for hot press forming and a manufacturing method thereof. Background technique [0002] Although high-strength steel sheets and their galvanized products have greatly improved the service strength and life of steel sheets, it is difficult to guarantee the good formability of higher-strength steel sheets, such as super-strong steel sheets with a strength of not less than 1500MPa, and the production process is difficult to solve The problem of shape fixity. [0003] In order to solve the forming problem of higher-strength steel plates, a forming process at high temperature has attracted widespread attention, which can well coordinate high strength and high formability. Publication No. JP2000-234153 discloses a process for forming a steel sheet while heating and using the heat generated during forming to increase the str...

AI Technical Summary

Problems solved by technology

For aluminum-silicon-coated steel sheets for hot-press forming, the sheet needs to be heat-preserved and formed at a temperature above 800°C, which requires that the coating itself not only have high heat resistance, but also have good formability, while the existing aluminum-silicon When coating products are hot-pressed above 800°C, coating liquefaction, peeling, adhesion to molds and other undesirable phenomena often occur. This may be due to the high content of Si in the coating solution and the relatively dense Al-Si-Fe phase between the coating and the substrate. , which almost completely blocks the diffusion of Fe due to

However, due to the lack of barriers of the Al-Si-Fe phase before hot pressing, the Al-Fe brittle alloy layer is relatively thick, and the coating in the large deformation area is easily broken from the interface during the forming process, resulting in peeling off of the coating and exposure of the substrate.