Aluminum Welding for Rail Transit

Common base metals and welds on rail car bodies

Modern high-speed EMU and rail vehicle bodies are largely welded from large hollow extrusions joined to thin-wall panels. An aluminum body is lighter, lowering running energy consumption and reducing wheel-rail loading, which makes aluminum welding a core process in car-body manufacturing. The base-metal combinations most commonly encountered on the floor are as follows:

• 6xxx-series extrusions (e.g. 6005A, 6082): widely used for large profiles in side walls, floors and roofs — adequate strength, heat-treatable, and the most common choice for the car-body frame.
• 5xxx-series plate (e.g. 5083, 5754): used on load-bearing parts, underframes and areas with higher corrosion-resistance requirements, with good strength retention after welding.
• Car-body welding is characterized by long seams, multi-pass joints and high-volume repeat welding of similar joints, so the wire's payoff smoothness, feeding stability and batch-to-batch consistency are especially critical — stable feeding directly affects production continuity and weld quality.

Practical welding notes

• Smooth feeding, fewer stoppages: whether welding by hand or with a wire feeder, feeding smoothness directly affects productivity. TGM wire has a clean surface and uniform diameter, giving low feed resistance and a stable arc, reducing feed stoppages and supporting continuous welding of long seams.
• Control distortion: car-body seams are long and thermal distortion accumulates readily. Plan the welding sequence sensibly, apply symmetrical welding and back-step welding, control heat input and interpass temperature, and use rigid fixturing to maintain car-body straightness and assembly dimensions.
• Layer-wound, stable payoff: TGM wire is layer-wound for smooth payoff without knotting or jumping, suited to long continuous welding and large packages (e.g. 7 kg / 18 kg spools), with stable de-reeling in high-volume repeat welding.
• Proper cleaning, adequate shielding: before welding, thoroughly remove the oxide film, oil and moisture, and shield with pure argon or an argon-helium mixture to reduce porosity and improve weld density. As rail structures carry fatigue loading over their service life, this step must be carried out rigorously.