Optimizing Mechanical Structures Through Butt Joining of Dissimilar Materials for Lightweight Components

Area of Science:

• Materials Science and Engineering
• Welding Technology
• Mechanical Engineering

Background:

• Joining dissimilar steels is vital for lightweight, high-performance structures.
• Material property differences present significant welding challenges.
• Optimizing welding processes for specific steel grades like S355J2 and Strenx 700E is essential.

Purpose of the Study:

• To optimize the butt-welding process for dissimilar S355J2 and Strenx 700E steels.
• To investigate the influence of surface preparation, linear energy, and joint gap on weld integrity.
• To identify optimal welding parameters for superior joint performance.

Main Methods:

• Cold Metal Transfer (CMT) welding was utilized.
• Systematic investigation involved tensile testing, digital image correlation (DIC), fractography, and microhardness analysis.
• Key process variables studied included surface cleaning methods, linear energy, and joint gap size.

Main Results:

• Optimal performance achieved with mechanical surface cleaning, low linear energy (0.334 kJ/mm), and a 0.5 mm joint gap.
• The optimized joint exhibited a tensile strength of 616 MPa, a 32% improvement over uncleaned samples.
• Uniform plastic deformation was observed across the joint, with a narrower heat-affected zone and no significant softening in the high-strength steel.

Conclusions:

• Mechanical surface cleaning, low linear energy, and a specific joint gap are critical for successful dissimilar steel welding.
• The optimized CMT welding parameters significantly enhance the mechanical properties and integrity of S355J2/Strenx 700E joints.
• This research provides valuable insights for the fabrication of advanced lightweight structures using dissimilar steel combinations.