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Laser direct joining of carbon fiber-reinforced thermoplastic composites (CFRTP) to aluminum alloy with diverse surface micro-patterns was performed. The influence of micro-pattern type on interface characteristic and mechanical property of CFRTP/aluminum alloy laser bonding joint was concerned especially. Prior to the laser joining, two different micro-patterns including groove structure and circular hole structure were fabricated on the metal surface using nanosecond pulsed laser. Then, the appearance of joint and the morphology at joining interface were observed by optical microscope and scanning electron microscope. Moreover, the tensile shear test was conducted to obtain the fracture load and fracture surface morphology. The results indicated that the cross section of the groove structure was a trapezoid, while that of the circular hole structure was a triangle with a large ratio of depth to diameter. In spite of the more pores existed at the interface of joints with circular hole structure, this type of micro-pattern strengthened the mechanical anchoring effect between CFRTP and aluminum alloy more significantly. With the change of micro-pattern from groove structure to circular hole structure, the maximum tensile load of laser bonding joint increased from 1616.40 to 2623.40 N, and the main failure mode transformed from interface failure to cohesive failure. The micro-pattern fabricated on the metal surface before the laser joining process is an effective approach to obtain the larger bonding area and higher mechanical strength of laser bonding joint. [ABSTRACT FROM AUTHOR]

In this investigation, a sinusoid modulated pulse gas metal arc welding (SP-GMAW) method based on a current waveform control method and on the welding mechanism of pulsed gas metal arc welding (P-GMAW) was proposed. This method achieved smooth control over the welding current. The process formulas were simplified. Then, the control parameters were discussed and optimized. Finally, three comparison experiments were conducted. The results indicated that the SP-GMAW method, as an improved double-pulsed gas metal arc welding (DP-GMAW) method, had the following features: The SP-GMAW minimized porosity rate and generated palpable weld ripples in contrast with the P-GMAW. The SP-GMAW produced the finest fusion zone grain, highest fusion zone microhardness, and highest tensile strength among three welding methods. The feasibility and superiority of the method for welding aluminum sheet were verified. [ABSTRACT FROM AUTHOR]