Objective Whole-vehicle lightweighting has become a focus issue in the technology development of new generation high-speed EMU (electric multiple unit). At present, various existing high-speed EMU trains in China still extensively use steel materials. On the basis of existing materials and structures, the space for weight reduction through structural lightweighting alone is highly limited. Therefore, it is necessary to carry out a systematic research on lightweight and high-strength materials to achieve whole-vehicle lightweighting for high-speed EMU.

Method A systematic analysis of titanium alloy materials application in high-speed EMU bogie frames is conducted, covering aspects such as material selection, component forming analysis, titanium alloy welding, post-weld stress relief treatment, and strength evaluation. A forge-welded titanium alloy frame with an I-beam structure as the main body is developed. Bench fatigue tests are performed to validate its material and structure, and line tests are carried out on lines with a maximum operating speed of no less than 400 km/h.

Result & Conclusion  The titanium alloy train frame can achieve a weight reduction of over 40% compared to existing steel frames. Due to its characteristics such as low density, high specific strength, and good corrosion resistance, the titanium alloy is widely used in the aerospace industry, and the bogie frame mass can be substantially reduced using titanium alloy. The dynamic stress distance in all parts of the titanium alloy frame is relatively larger compared to the fatigue limit, and the safety margin is also significantly higher than that of existing steel frames.