EFFECT OF SUBMERGED-ARC PROCESS VARIABLES ON DILUTION AND BEAD GEOMETRY IN SINGLE WIRE SURFACING

Weld surfacing is the technique of depositing a layer of material onto the surface of a component to make it more resistant to wear, corrosion or high temperature than the parent metal or substrate. This enhances production economies by enabling the use of a cheaper, more easily machinable parent material coated with expensive metals and alloys for achieving desired properties in specific areas of products. It has become more popular than the pre-cladding of materials as it is employed at the final stage of fabrication. Weld surfacing is employed for the fabrication of new components for use in chemical and fertilizer plants, nuclear power plants, pressure vessels, agricultural machines and even aircraft and missile components. Also, it has been used widely for maintenance and repair of railway rolling stock as well as points and junctions, earth moving and agricultural machinery, large gear wheels, conveyor shafts, chutes, turbine components and innumerable other components. Though weld surfacing is carried out by various techniques, automated submerged arc welding is the popularly employed technique due to its high quality and reliability. Also, by the proper selection of the process control parameters, single wire surfacing becomes one of the cost effective means of depositing a corrosion resistant overlay. However, for use of SAW in its automatic mode, the control parameters are required to be fed to the system according to some mathematical formulation to achieve the desired end results: the present paper deals with the development of such models. Mathematical models were developed by using a five level factorial technique to predict the weld bead geometry for depositing 316L stainless steel onto structural steel IS 2062. The responses, namely, penetration, reinforcement, width and dilution as affected by open-circuit voltage, wire feed-rate, welding speed and nozzle-to-plate distance, have been investigated. The models developed have been checked for their adequacy and significance by using the F-test and the t-test, respectively. The main and interaction effects of the control factors on dilution and bead geometry have been presented in graphical form, which is more useful in selecting the process parameters to achieve the desired quality of the overlay.