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

## TL;DR

This paper shows how to improve the strength of welded steel joints by optimizing welding parameters and surface preparation.

## Contribution

The study introduces an optimized butt-welding method for dissimilar steels that enhances joint strength and deformation behavior.

## Key findings

- Mechanical surface cleaning with low linear energy and a 0.5 mm gap improved joint tensile strength by 32%.
- Optimized welding produced uniform plastic deformation and a narrower heat-affected zone.
- Microhardness analysis showed no significant softening in the high-strength steel.

## Abstract

The joining of dissimilar steels is crucial for designing lightweight, high-performance structures but poses significant challenges due to uneven material properties. This study optimizes the butt-welding process for a dissimilar pair of S355J2 and Strenx 700E steels. Cold Metal Transfer welding was employed, and the effects of surface preparation, linear energy, and joint gap on joint integrity were systematically investigated via tensile testing, digital image correlation, fractography, and microhardness analysis. The results demonstrate that mechanical surface cleaning combined with a low linear energy of 0.334 kJ/mm and a 0.5 mm gap yields optimal performance. This parameter set produced a joint with a tensile strength of 616 MPa, representing a 32% increase compared to uncleaned samples, and promoted uniform plastic deformation across the joint. Microstructural analysis confirmed a narrower heat-affected zone and the absence of significant softening in the high-strength steel.