| Metal powder flux-cored wire is widely used in bridge engineering, ship, aerospace, pipeline engineering. However, the current report about the metal powder flux-cored wire was concertrated on its process, the welding arc physical characteristic of research was rarely reported. Arc physics theories of welding material, including the metal transfer mode, the physical mechanism of metal transfer, arc behavior and characteristics of electric arc parameters etc. is one of the most important theory for guiding to enhance the level of operational behavior and improve the quality of welding materials as well as for scientific and quantitative evaluation of its operational behavior.At present,the report on the arc physical characteristic research mainly concentrated on the droplet transfer characteristics&mechanism, welding spatter characteristics&mechanism and the change of welding electric parameters, at the same time according to the change of welding electric parameters,through the mathematical method to build a model to evaluation the stability of welding process, the stability of droplet transfer and the severity of spatter.The paper on a base of analyzing two typical commercial metal powder flux-cored wire, use the high-speed photography and the ANALYSATOR HANNOVER as well as welding spatter test methods and the numerical experiment at different voltage, to research the characteristic of arc physical.The matal transfer of metal powder flux-cored wire include:short circuiting transfer、globular repelled transfer、fine transfer、spray transfer、explosive transfer。When the short circuiting transfer take place,the metal is contact with the molten pool when it is not big enough,the liquid bridge is formed.The current in the liquid bridge increase rapidly as well as the electromagnetic retractile power increase rapidly. Through the interaction of the surface tension of the molten pool and the electromagnetic retractile power the metal transferred to the molten pool.Because of the spot pressure resisit the transfer of matal at the globular repelled transfer,the charactersticsof gobular repelled transfer is the bigger drop size, the lower metal transfer frequency, the more spatter, the worse arc stability and the lower melting efficiency.Because of the increase of the voltage,lead to the increase of plasma power and electromagnetic retractile power as well as the decrease surface tension,the metal transferred to the molten pool when the metal is not big enough.The the charactersticsof fine transfer、spray transfer are the smaller drop size, the size is almost equal to the wire diameter,the metal transfer frequency is higher, the welding process is stable, the spatter is less, the appearance of weld is better.The explosive transfer is take placed when the gas inside the metal expansion rapidly lead to the explosive of metal.The spatter of metal powder flux-cored wire include:electro-explosive spatter,spatter created by arc force,spatter created by metal burst, necking spatter, bubble release spatter.Through the statistical analysis of instantaneous value of the arc voltage, it unfolds that the approximate entropy of arc voltage can be used to assess the stability of metal transfer. The higher the average approximate entropy of arc voltage is, the lower the approximate entropy standard deviation will be, and the more stability of metal transfer.Through the PLSR establish mathematical model between the average voltage, E n(UB), E n(Is), the coefficient of variation of voltage and the severity of spatter. the result indicate:that the lower the average voltage is, the higher the Σn(UB) will be; the higher the Σn(Is), the more serious the spatter of metal powder flux-cored wire will be. Furthermore, the effects of the high voltage probability density are the biggest, the effects of high current probability density comes next, whereas the effects of average voltage and the coefficient of variation of voltage is relatively small. |
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