Alloy plate for automobile body and preparation method thereof

Abstract

The invention provides an alloy plate for an automobile body and a preparation method of the alloy plate. An alloy comprises, by mass percentage, not larger than 0.4% of Si, not larger than 0.4% of Fe, 0.2-0.5% of Mn, 3.0-6.0% of Mg, not larger than 0.03% of Cr, not larger than 0.15% of Cu and the balance Al and impurities. According to the alloy plate and the preparation method, by controlling the content of the trace element Cr and the final annealing process and the straightening amount, on one hand, the YPE of the plate is reduced, and on the other hand, the plate still has excellent mechanical and forming properties of the material. The preparation method comprises the following steps that final annealing is carried out on a continuous annealing line, wherein the temperature rise speed is larger than 20 DEG C / s, and after heat preservation at 480-520 DEG C is carried out for 15 s and 5 min, water quenching is carried out, and the cooling speed is larger than 10 DEG C / s; the finalgrain size should be controlled at 20-40 micrometers, and the YPE is smaller than or equal to 0.2%; and the final annealing plate is subjected to straightening treatment, and the straightening amountis 0.5-1%. The plate prepared by the method is suitable for an automobile body structural member and an automobile body covering panel inner plate.

Description

technical field [0001] The invention relates to an alloy and a preparation method thereof, in particular to an alloy plate for a vehicle body with a low yield point elongation and a preparation method thereof. [0002] technical background [0003] With the development of the automobile industry, the sales of automobiles have increased year by year, which has brought great pressure to energy and the environment. On the premise of ensuring the strength and safety performance of the car, minimizing the overall mass of the car can effectively reduce fuel consumption and reduce exhaust pollution. Aluminum alloy has become the ideal material of choice for lightweight vehicles due to its excellent strength, high rigidity, good impact resistance, excellent formability and high recycling rate. [0004] As the commonly used automotive body structural parts and inner panels, the 5xxx series aluminum alloys require not only good mechanical properties and excellent formability, but also...

AI Technical Summary

Problems solved by technology

[0010] CN 109988948 A Chinese patent proposes a production method of 5xxx series aluminum alloy plates, but the main measure is to improve the baking strengthening performance of the plates by adding Cu and Zn elements, but it does not involve YPE

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