Effect of Different Coating Composition's Rutile-type Welding Electrodes on Undercut Defect in Manual Electric Arc Welding

摘要

This study is the part of a program to obtain the fundamental knowledge about the effect of electrode coating composition on the undercut defect of welding specifically in Manual Metal Arc Welding (MMAW) process. Undercut in welding is one of the prime defects which are given special care as its severity increases manifolds due to, firstly the stress concentration caused by it in the parent material and secondly further weakening of HAZ where it is formed. Undercut has been a very serious issue in the fabricating industry since a long time for which many solutions like weaving technique etcetera have been probed out. The root cause behind the formation of the undercut is the application of excess heat. This excess heat comes due to the application of over amperage. Conventionally undercut is controlled by controlling the current value of the process. This paper is an attempt to search for alternative solution to cater the same problem specially while employing semi skilled and unskilled labor for the process. The excess heat can also be absorbed by using controlled amount of some endothermic materials for making the electrode coating during arc welding. The present work is mainly focusing on the rutile electrode group in which by varying the constituent and composition of endothermic materials in electrode coating materials in controlled manner can control the excess temperature gradient which leads to the reduction of undercut so formed.