Research Of Twin-wire Efficient Gas Shielded Overlaying

Overlaying is one of the important ways to improve the mechanical parts surfaceproperties. It can not only repair the old metal parts, but also overlay a composite layeron the surface of workpiece. It can give the mechanical parts some special properties,so as to improve the surface quality, increase the working life and reduce the cost. Nowoverlaying is almost a single-wire overlaying technology. It has the disadvantages oflow cladding efficiency and high-dilution.In order to solve the problems of the single-wire overlaying technology, a newtype of twin-wire overlaying technology was put forward. Twin-wire efficient gasshielded overlaying is a novel overlaying technology. Arc burns between the two wires,instead of between the wire and base metal like single overlaying. The arc heat from arccolumn and high temperature droplets are used to melt the base metal. The advantagesof this technology are low-dilution, high deposition rate, power saving, low stress anddeformation. It is a new kind of overlaying method with high quality, high efficiencyand energy-saving. It has higher application foreground.Twin-wire efficient gas shielded overlaying parameters have important influenceon the arc stability, appearance of overlaying layer, overlaying quality and overlayingefficiency obviously. Overlaying current, arc voltage, wire feed speed, the distancebetween the wire top and the work-piece, and overlaying speed are importantprocessing parameters in the overlaying. In order to get better overlaying layer, theoverlaying speed must fit for the other overlaying parameters.Twin-wire overlaying experiments were carried out under the protection of CO2gas. The optical microscope, scanning electron microscopy, energy dispersivespectrometer and microhardness tester are used to analyze the microstructure,composition and property of the overlaying layer and the interface between theoverlaying layer and base metal. The experimental results shows that a uniform, adherent and low-dilution overlying layer can be obtained after twin-wire efficient gasshielded overlaying.