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Abstract
The welding process plays an important role in the construction of petroleum and chemical projects. However may often some defects result during manufacturing executed , which must be repaired. The repair process must be carefully studied to reduce the risk of re-repair. Previous studies showed that the repair process can affect the mechanical properties of the welded joint and consequently reduce the life time of the item .The aim of this study is to investigat the effects of using the austenitic ferritic stainless steel filler metal in repair of defective carbon steel welded joint and to study the effect of this repair by this filler metal on the mechanical properties of welded joint. In this work ,steel SA 516 G70 ( had been used as the base metal) which is commonly used in the construction of LPG spherical tanks in welded joint a high strength medium carbon steel ,and thus requires great care during welding in order to produce a sound weld. A WPS based on electrode E7018-1 had been applied to produce one sound joint used as a reference and three joints with artificial defects . The repair procedure began by grinding off the defective area , removing the defect preparing for special repair. Three types of electrodes had been tried , low hydrogen electrodes carbon steel electrodes E 7018-1 , low alloy steel electrodes E8018-G and austenitic ferritic stainless steel electrodes E309L-16 .After repair ,,the joint was examined metallographically and tested mechanically under tensile .hardness and impact tests. Comparisons are made between the qualities of the joints repaired by the different electrodes.