The Effect of Laser Structuring on Hot-Press Joined Metal-Polymer Cross Tension Joints

Abstract This study examines the effects of laser surface structuring on the cross-tension strength of metal-polymer hybrid joints, focusing on ASTM A1008 steel and two polymers: high-density polyethylene (HDPE) and polyamide with 50% glass fiber (PAGF50%). By varying laser parameters—such as power, scan speed, repetition count, hatch distance, groove patterns, and polymer thickness—the results show that optimal joining strength for steel-HDPE cross-tension specimens is achieved when the hatch distance is smaller than the effective groove width, which includes the recast structures, with minimal influence from repetition count and pattern. Notably, thicker HDPE specimens (5 mm) exhibited up to 54% greater joining strength than thinner ones (3 mm), attributed to enhanced resistance to deformation. Maximum strength for PAGF50% was achieved with a single repetition and a transverse groove pattern, leveraging recast structures that promote chemical bonding. Analysis indicates that cross-tension specimen strength is generally lower than that of T-joints due to edge-initiated fractures, underscoring the importance of specimen dimensions. These findings provide practical guidelines for optimizing laser structuring parameters to enhance joint performance in high-strength, lightweight metal-polymer applications.