Investigation on Failure Conditions in DRAWING METAL POWDER-CORED RODS
International Journal of Modern Manufacturing Technologies
The metal-cored wires/rods are promising and widely used welding materials for electric-arc welding. Used for specific applications metal-cored rods give the benefit of being able to have alloy compositions formulated for a certain technological purpose having high deposition rate and efficiency, high travel speed and low slag volume. During the manufacturing process by drawing through a series of dies, both sheath and powder-core deform. The initially non-compacted mixture of powder is
... ively, densified and its density/porosity is redistributed as radial and longitudinal gradients over the internal volume of the rod in all stages of drawing. The higher the compactness degree of the powder-core, the higher the arc welding stability and the quality of the deposited material. The features of the drawn metal-cored rods strongly depend on the internal pressure exerted by the sheath on metal powder and vice versa. Inherent failure of the sheath will appear if a proper processing design (i.e. sequence of drawing, partial/total reduction, friction, initial coefficient of fullness, etc.) is not set. The paper aims to investigate the behavior of the sheath and metal powder as whole to prevent the failure in drawing metal-cored rods. Two drawing sequences having different process and material parameters were analyzed and the optimum scenario was chosen to keep the sheath of the rod during drawing. It was found that decreasing the reduction during first passes could preserve the rod, which can become the starting point to obtain an optimum starting point for further drawing.