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The interfacial bonding process and mechanical properties of AISI (American Iron and Steel Institute) stainless steel/Q235A carbon steel were investigated by deformation bonding, heat preservation, and tensile tests. The results reveal that the deformation temperature has a beneficial effect on the bonding rate, and that the critical temperature for the large-area bonding of stainless steel and carbon steel is approximately 700 °C. However, owing to the short contact time, only a shallow diffusion of approximately 2–3 µm can be achieved. A slight decrease in the interfacial bonding rate after heat preservation is correlated to the difference between the thermal expansion coefficients of the two materials, but the thickness of the diffusion layer shows a significant increase. It was found that the strength of the composites is mostly related to the bonding rate and the strength of the relatively soft material, which can be determined using an explicit equation. Moreover, with the increase in the interfacial bonding rate, the crack source changes from the junction of the unbonded and bonded areas of the interface to the interior of the carbon steel. The failure mode evolves from cleavage brittle fracture to ductile–brittle mixed-mode fracture, and then to ductile fracture.

Two types of ultrasonic transducers: full ceramics (lead zirconate titanate, PZT) and composite (PZT embedded in a polymer) transducers, were used for wire bonding. Al wire is 32 μm in diameter and bond pads contain Au/Ni/Cu trilayer coating on PCB boards. Bonding Al wire on the pads was processed on three different power levels and with various bond times at each bond power to compare the bonding performance of the two types of transducers. The actual bond areas were measured after the Al wire had been removed in a base solution. Bonding kinetics was analyzed based on actual bond areas. Pull strength test was used to examine bonding quality. The fractured bonds were examined using a scanning electron microscope.The results show that the bonding rate by the full ceramic transducer is faster than that by the composite transducer in the initial stage. A maximum bond strength is attained after a certain bond time which is different depending on the bond power. This maximum bond strength produced by the composite transducer occurs at longer bonding time. The widths of the bonds produced by the composite transducer are significantly narrower than those of the bonds produced by the full ceramic transducer. The reduced bond width gives rise to higher bond strength. [Copyright &y& Elsevier]

The interfacial bonding process and mechanical properties of AISI (American Iron and Steel Institute) stainless steel/Q235A carbon steel were investigated by deformation bonding, heat preservation, and tensile tests. The results reveal that the deformation temperature has a beneficial effect on the bonding rate, and that the critical temperature for the large-area bonding of stainless steel and carbon steel is approximately 700 °C. However, owing to the short contact time, only a shallow diffusion of approximately 2–3 µm can be achieved. A slight decrease in the interfacial bonding rate after heat preservation is correlated to the difference between the thermal expansion coefficients of the two materials, but the thickness of the diffusion layer shows a significant increase. It was found that the strength of the composites is mostly related to the bonding rate and the strength of the relatively soft material, which can be determined using an explicit equation. Moreover, with the increase in the interfacial bonding rate, the crack source changes from the junction of the unbonded and bonded areas of the interface to the interior of the carbon steel. The failure mode evolves from cleavage brittle fracture to ductile–brittle mixed-mode fracture, and then to ductile fracture. [ABSTRACT FROM AUTHOR]