Laser Welded High-Strength Steel Tubes

High-strength steel tubing for new-energy automotive chassis and lightweight structural components

Laser Welded High-Strength Steel Tubes
  • Laser Welded High-Strength Steel Tubes
  • Laser Welded High-Strength Steel Tubes
  • Laser Welded High-Strength Steel Tubes
  • Laser Welded High-Strength Steel Tubes

    • Laser-welded tubes are widely used in ≥800 MPa high-strength steel roll-forming and high-speed welding applications:

    • Minimal deformation & high precision
      Laser welding of high-strength steel produces extremely small weld deformation, ensures high dimensional accuracy, delivers stable welding quality, provides high joint strength, reduces energy consumption, and eliminates the need for post-weld heat treatment.
    • Lightweight & higher performance for NEV chassis
      When applied to new-energy vehicle chassis, laser-welded high-strength steel tubes can achieve 10–30% weight reduction, while improving strength, rigidity, and fatigue performance by 30–50%.
    • Growing demand with new-energy vehicle development
      As the global demand for new-energy vehicles continues to expand, the demand for laser-welded high-strength steel tubes will continue to grow in parallel.
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    Inspection Requirements
    Performance Testing

    Performance Testing: Flattening / Flaring

    • Standard distance between compression plates after flattening ＜ 2T + 1 mm;
    • National standard requirement: distance between plates = 1/3 of the pipe outer diameter;
    • Under both standards, the welded seam must show no cracks, tears, or weld failure to be qualified.
    • For the flaring test, a 200–300 mm section is taken and a 180° flanging test is performed using a special mold.
    • Qualification requirement: no tearing or cracking at the weld seam during outward flanging of the pipe wall
    Metallographic Testing

    Metallographic Testing: Fusion Line

    • Japan Nippon Steel standard width: 0.02–0.20 mm
    • Germany standard width: 0.02–0.12 mm
    • Korea PSP standard width: 0.05–0.30 mm
    • Standard fusion line width of the weld zone is controlled within 0.02–0.11 mm, observed under 100× microscope
    • Metallographic Testing
    • Metallographic Testing

    Metallographic Testing: Streamline Angle

    • Japan Nippon Steel requirement: 40°–70°
    • Germany requirement: Inner wall 60°, outer wall 65° (tolerance ≤ 10°)
    • Company control standard: streamline angle at the weld zone is controlled within 50°–70°

    Laser welding of high-strength steel produces minimal deformation at the weld seam, delivers high joint strength, and does not require post-weld heat treatment. When applied to new-energy vehicle chassis, strength, stiffness, and fatigue performance can be improved by 30–50%, while weight can be reduced by 10–30%. In addition, weld reliability is further ensured through flattening tests (no cracking), flaring tests (no tearing), metallographic control of fusion line width (0.02–0.11 mm), and streamline angle (50°–70°), helping prevent weld cracking during collisions and enhancing overall safety performance.

    The characteristics of laser-welded high-strength steel tubes, such as minimal weld deformation, high joint strength, and no requirement for post-weld heat treatment, combined with strict metallographic control of fusion line width (0.02–0.11 mm) and streamline angle (50°–70°), as well as verification through flattening (no cracking) and flaring (no tearing) tests, significantly enhance weld reliability. As a result, fatigue strength of key structural components can be improved by 30–50% compared with conventional tubing, helping construction machinery withstand high-frequency, heavy-load operating conditions with enhanced durability.

    Laser welding parameters must be adjusted according to the strength level and material characteristics of different high-strength steel grades, including optimization of laser power, welding speed, and related process parameters. Proper parameter matching ensures minimal weld deformation and high joint strength, while maintaining fusion line width and streamline angle within required standards. At the same time, weld seams must pass flattening and flaring tests without cracking or tearing to avoid inconsistent weld quality or insufficient mechanical performance caused by parameter mismatch.