Metal cored wires are often used in gas metal arc welding to increase productivity. Cored wires can, however, also easily be designed to affect weld metal composition or arc characteristics. Specially formulated metal cored wires, designed for laser hybrid welding, could therefore potentially be used to improve the arc and weld pool characteristics and enhance the process flexibility, robustness and productivity. The range of process parameters available in hybrid welding could thereby be extended and the process stability improved further for standard parameters.
Small additions of certain elements in the wire can influence the arc plasma state and the surface tension, resulting in an altered arc and weld pool behaviour. A number of metal cored wires have therefore been produced containing additions of several different arc stabilising elements, varied from 0-10% of the powder filling.
High speed filming of the welding process with synchronised arc current and voltage measurements was conducted enabling e.g. to detect short short-circuiting. Preliminary results indicate differences in process stability, arc length, surface appearance and penetration profiles between the wires in pulsed mode transfer. The experimental results are accompanied by a theoretical discussion of the phenomena observed, including the use of the Saha equation to calculate electron number density as a function of temperature for relevant chemical elements.