Electrode quality steel for core wire of covered electrodes...

Electrode quality steel for core wire of covered electrodes Covered welding electrode is a delicate tool which while in use combines physical, chemical, and metallurgical processes of the flux, core wire and parent metal to achieve a durable weld joint or surfacing. Covered welding electrodes are used in manual metal arc welding (MMAW) process. During the 1890’s, electric arc welding was accomplished with bare metal electrodes. The welds produced were porous and brittle because the molten weld puddle absorbed large quantities of oxygen and nitrogen from the atmosphere. Since 1927, many improvements have been made and many different types of electrodes have been developed and produced through variations in the formulations of the covering and the amount of covering on the mild steel core wire. Commercial production of welding electrodes was started in India in early 1960s. Mild steel covered electrodes, also commonly called coated electrodes, consist of only two major elements namely the core wire or rod and the flux covering. The raw material for the core wire is hot rolled wire rod which is supplied in coil form. Wire rod is cleaned, drawn down to the proper electrode diameter, straightened, and cut to the required electrode length. The most popular diameter of wire rod is 5.5 mm, although larger diameters are also used in a limited way. In covered welding electrode the product mix is of mild steel electrodes (around 60 %), mild steel high tensile and low hydrogen low alloy (around 30 %) and special type (around 10 %). Fig 1 shows EQ steel wire rod, EQ steel drawn wire and covered welding electrode. Fig 1 EQ steel wire rod, EQ steel drawn wire and covered welding electrode.  Core wire is an important component of a manual electrode since it significantly influences the electrode performance...