| Title |
Circular Arc-Plug Welding in Automotive Architecture: Microstructural Characterization and Mechanical Properties Evaluation of Advanced High-Strength Steels |
| Authors |
(Arun Lalachan) ; (Savyasachi Nellikode) ; (Jae-Deuk Kim) ; (Jeong-Hwan Jo) ; (Doo-Young Kim) ; (Ho-Young Kong) ; (Woo-Young Chung) ; (Chang-Wook Ji) ; (Joo-Yong Cheon) ; (Yeong-Do Park) |
| DOI |
https://doi.org/10.3365/KJMM.2026.64.6.512 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Arc-plug welding; Advanced high-strength steels; Microstructural characterization; Mechanical properties evaluation; Automotive applications; Welding consumables |
| Abstract |
Advanced high-strength steels (AHSS) are extensively employed in automotive structural
components due to their superior mechanical properties, enabling weight reduction and enhanced safety. Among
joining techniques, arc-plug welding (APW), a variant of gas metal arc welding (GMAW), presents a viable
single-sided welding method suitable for complex assemblies where conventional methods such as resistance
spot welding (RSW) face accessibility limitations. However, systematic investigations on the influence of welding
consumables on the microstructural evolution and mechanical performance of APWs in AHSS remain limited.
This study evaluates the effect of two welding consumables?ER70S-6 and ER110S-G?on the microstructure
and mechanical behavior of APWs performed on 1.0 mm thick, 1180 MPa grade AHSS sheets. The APW process
involved a 6 mm diameter plug hole with controlled welding parameters optimized individually for each
consumable. Microstructural characterization of the weld zone (WZ) and coarse-grain heat-affected zone
(CGHAZ) was conducted using optical microscopy, scanning electron microscopy (SEM), and electron backscatter
diffraction (EBSD). Mechanical performance was assessed through Vickers microhardness profiling, tensile
shear testing (TST), and cross-tension testing (CTT). Results reveal that ER70S-6 welds exhibit a microstructure
dominated by grain boundary ferrite (GBF) and acicular ferrite (AF), which impart higher ductility but lower
hardness (~300 HV) in the WZ. Conversely, ER110S-G welds display a bainitic microstructure characterized by
lath and granular bainite (LB and GB), resulting in increased hardness (~450 HV) and higher strength, albeit
with reduced toughness. Mechanical testing demonstrated that ER110S-G welds achieved marginally higher
tensile shear strengths compared to ER70S-6 welds. Failure analysis indicated a shift in fracture mode from
weld zone pullout in ER70S-6 welds to CGHAZ fracture in ER110S-G welds, reflecting the microstructural and
hardness variations. Cross-tension tests further corroborated these observations, showing ductile failure
behavior for ER70S-6 and brittle fracture tendencies for ER110S-G. |