Process Stability of Ultrasonic-Wave-Assisted Gas Metal Arc Welding
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DUCTION
GAS metal arc welding (GMAW), as a kind of arc welding method, applies consumable electrodes and protects metal droplets, weld pools, and high-temperature metal in the welding zone using shielding gases. Owing to advantages, such as low cost, well adaptability, and ease of automatization, the GMAW process is more suitable for all welding positions and has been a research focus in the field.[1–3] According to the composition of the wire and the variation of the welding parameters, the metal transfer of the GMAW can be classified as short-circuiting transfer, globular transfer, and spray transfer.[4] Since the metal transfer has crucial effect on the weld quality and the process stability, the active control technology of the GMAW metal transfer attracts many researchers’ attention.[5] Metal transfer has been one of the hot research topics in the welding field. Anzehaee et al. proposed a new method to employ the melting rate, heat input, and detaching droplet
CHENGLEI FAN, CHUNLI YANG, and SANBAO LIN are with the State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China. WEIFENG XIE is with the School of Mechanical Engineering, Northeast Electric Power University Jilin, Jilin 132012, China. Contact e-mails: [email protected], [email protected] YANGYANG FAN is with the Sichuan Xiye New Material Co. Ltd., Chengdu 611700, China. Manuscript submitted October 16, 2016.
METALLURGICAL AND MATERIALS TRANSACTIONS A
diameter as controlled variables to control heat and mass transfer.[6] The TRIFARC method used an extra wire with the reverse electric current, which was inserted between the electrodes of the standard to control the molten droplet and pool.[7] Nemchinsky and Meyer stroke an additional arc on the droplet, which serves as the cathode to regulate the current distribution and metal transfer.[8] Huang et al. decoupled the undesired dependence of the metal transfer on the current and used laser to facilitate the droplet detachment from the wire tip.[9,10] The simplest metal transfer control strategy is to use the pulse current, which can get ‘‘one pulse one droplet,’’ and this method has been widely used in the industry. However, this technique still cannot achieve the target of accuracy control. In order to further improve the welding quality, some researchers used arc light/spectrum,[11] magnetic field,[12] or even arc sound[13] as the characteristic signal to control the welding parameters. Some want to use external energy, such as mechanical vibration,[14,15] extra arc,[16] and extra welding wire,[17] to control the metal transfer. The authors present a new metal transfer control idea—using the ultrasonic radiation force to control the droplet, a method called ‘‘ultrasonic-wave-assisted GMAW’’ (U-GMAW).[18] Under the action of the ultrasonic radiation force, no matter the transfer type (short-circuiting or globular transfer), the volume of the droplet is decreased and the transfer frequency is increased. Besides, the arc becomes contractive and the directivity of
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