Laser direct joining of carbon fibre reinforced plastic to stainless steel

This study was performed to evaluate the characteristics and strengths of dissimilar joints between carbon fibre reinforced plastics (CFRP) and stainless steel using high brightness continuous wave disc laser. Tensile shear tests demonstrated that strong CFRP steel joint with similar to 4800 N could be produced. The joints were tightly bonded on atomic or molecular sized level through Cr-Fe oxide film on the metal surface, and small fragments of type 304 steel were detected on the fractured CFRP. Many bubbles of submillimetre size were formed all over the plastic melted zone in the CFRP. The gas compositions inside the bubbles were H-2 and hydrocarbon series as pyrolysis gases of the CFRP as well as N-2 in air. These results suggest strong chemical and physical bonding of the CFRP on the oxide film of the type 304 plate. Consequently, it was confirmed that a strong joint could be produced between CFRP and type 304 stainless steel with a laser beam.