South South Aluminium breaks key technology of aluminum alloy section of 350km high-speed train

CRH380A is a new type of high-speed EMU independently researched and developed by China CSR Qingdao Sifang Locomotive & Rolling Stock Co., Ltd. on the basis of the CRH2 EMU. Its operating speed is 350km per hour. Its body is made of aluminum alloy hollow sections assembled and welded.

The high-speed operation of the train, as well as the changing service environment in China such as high temperature, high humidity, and coastal areas, make the high-speed rail and its aluminum alloy materials have more excellent comprehensive performance. The Japanese aluminum processing industry, which grew up along with the development of the Shinkansen, has accumulated over 50 years of technical experience in high-speed aluminum alloy materials.

Currently occupy a large number of high-speed rail aluminum market in China, the most typical product is 7N01-T5 aluminum alloy profiles.

7N01 is a Japanese aluminum alloy brand, similar to our 7B05 alloy, and it is a typical AlZnMg alloy. It has the advantages of moderate strength, good extrusion performance, and high welding coefficient. It is mainly used for CRH2 and its derivatives in China. However, this alloy has a certain degree of stress corrosion tendency. In addition, the special operating environment of high-speed iron also puts forward higher requirements for the comprehensive performance of aluminum alloy profiles such as fatigue, fracture toughness, and welded joints.

Nannan Aluminum began to develop 7N01 profiles since it started production at the extrusion manufacturing center. The research and development team consisting of senior casting and extrusion experts at home and abroad, led by the chief scientist of China's aluminum 973, conducted the 7N01 melting and casting, mold design, extrusion and heat treatment.

Nannan Aluminium adopts advanced aluminum alloy casting production line, so that the quality of 7N01 melt is better than that of aviation ingots. Using the company's existing multi-level temperature control soaking furnace and the integration of the aging furnace AlZnMgCu alloy T7751 dedicated state aging furnace, combined with the calculation results of the second phase nucleation free energy, designed a heat treatment process with independent intellectual property rights.

The project has developed independently over two years and accumulated a large amount of research results on 7N01 profiles, and finally formed a quality management system for the stable production of 7N01 profiles. The inspection and analysis conducted by various authorities showed that the mechanical properties, fatigue strength, and corrosion resistance of welded joints of 7N01-T5 produced by South-South Aluminum Processing Co., Ltd. were comparable to those of Japanese profiles, and the stress corrosion resistance, spalling corrosion resistance, and fracture toughness were far superior. Imported profiles.

Nannan Aluminium is the first and only aluminum processing company in China that achieves a breakthrough in the 7N01-T5 profile performance index. The company has now successfully delivered 7B05 (7N01)-T5 aluminum alloy profiles for the CRH380A EMU. The success of the project has also driven the technical development of domestic aluminum processing counterparts, which is of great significance for improving the overall technical level of aluminum processing in China.