How to optimize the production process of 6XXX series aluminum alloy automobile sheet?

As a representative material for automobile lightweight, aluminum has become a key raw material for reducing the weight of the automobile body for the development of the automobile industry today. The formability and production performance of aluminum sheets are very close to those of steel sheets, so the use of aluminum alloys instead of steel materials is one of the main weight reduction methods adopted by automobile manufacturers in various countries.

1.Market Overview of Aluminum Alloy Automobile Sheets at Home and Abroad

1.1 Application of aluminum alloy automobile sheet in new energy automobile industry

From January to November 2021, the sales volume of new energy vehicles in my country reached 2.99 million, a year-on-year increase of 1.7 times. The rapid development of the new energy vehicle industry is closely related to the development of technologies such as batteries, automatic control, and new materials. In the absence of major breakthroughs in battery technology, body weight reduction is still an important research topic in the new energy vehicle industry. Aluminum alloy materials have the advantages of high specific strength, corrosion resistance, and high recovery rate (1). Aluminum alloy castings have been used in engine chassis systems for a hundred years, but the development of aluminum alloy automotive panels used in body panels has been relatively slow. Before 2010, there were only a lot of applications in some high-end models (such as Audi A8). As a leading company in new energy vehicles, La Company took the lead in applying all-aluminum body, and its carbon credit management has been very effective. The commissioning of Tesla's super factory in Shanghai has also led to the rapid development of the domestic new energy vehicle industry. The sales of new energy vehicles with all-aluminum bodies represented by Weilai were once eye-catching.

1.2 Supply Status of Aluminum Alloy Automotive Sheet

In the early days, well-known aluminum processing companies such as Alcoa, Alusuisse, and Alcan cooperated with automobile OEMs such as Leyland, Ford, and Jaguar Land Rover. Rover) to develop customized aluminum alloy automotive panels and achieve exclusive supply. With the demand for lightweight automobiles and the development of the new energy automobile industry, as well as the cost pressure of automobile OEMs, the technical requirements of aluminum alloy automobile sheets have a trend of standardization. For example, the European VDA standard has unified the technical indicators of aluminum alloy automobile sheets: currently the world's largest aluminum alloy Auto sheet supplier Novelis will achieve a total production capacity of 1 million t/a in 2020 at its plants in North America, Europe, and Asia through new additions and mergers and acquisitions. Over the past ten years, China has invested in the construction of aluminum alloy automobile production lines. Due to market and technical constraints, mass production has only begun in recent years. In 2020, domestic aluminum alloy automobile sheet suppliers include Nanshan Aluminum, Nannan Aluminum, and Chalco Ruimin. The total production capacity of companies such as Zhongwang Group and Zhongwang Group is about 400,000 tons, and the new production capacity is expected to be 120,000 tons in 2022. At present, the production capacity of aluminum alloy automotive sheets at home and abroad is still expanding steadily, and the supply and demand have not yet reached a balanced state.

2.Aluminum alloy automotive sheet production technology and equipment bottleneck.

The main alloy grades of 6xxx series aluminum alloy automotive sheets include 6016, 6014, 6022, etc., which are the main aluminum alloys currently used in body outer panels. Automobile sheets have high requirements on comprehensive performance, surface quality and quality stability. The current mainstream aluminum alloy automotive sheet production process is relatively complex, including several major processes: melting and casting, soaking, machining, hot rolling, cold rolling, and continuous heat treatment.

The 6xxx series aluminum alloy automotive sheet needs to have good stamping and flanging performance, natural aging resistance stability, good strength increase of baking paint, and no Luoping line on the surface of the material after stamping. In order to meet the special performance requirements of automobile panels in automobile OEMs, not only qualified cold-rolled billets are required, but also special heat treatment technology and production equipment are required. The production capacity of aluminum alloy automotive sheets is mainly limited by the heat treatment technology and equipment.

The growth of demand for aluminum in the new energy automobile industry has accelerated the development of the domestic aluminum alloy automobile sheet industry. The maturity of domestic aluminum alloy auto sheet technology has been significantly improved, and the product quality can be compared with that of imported auto sheets, which has partially replaced imports. With the expansion of new energy vehicle production capacity and the further increase in demand for aluminum materials, the aluminum processing industry needs to promote the localization of key production equipment air cushion continuous heat treatment furnaces. At the same time, under the background of carbon emission policies, it is necessary to speed up the recycling of aluminum alloy automotive sheets The R&D, trial production and verification of the company can realize the recycling of aluminum used in the body, and achieve the purpose of energy saving and emission reduction in the whole life cycle of the car.