PAPER TITLE :INFLUENCE OF ELECTRODE COATING ON MECHANICAL PROPERTIES OF STRUCTURAL STEELS

JOURNAL Of SUSTAINABLE TECHNOLOGY | VOLUME 4 NUMBER 1 2013

Paper Details

  • Author(s) : IWUOHA, A.U.
  • Abstract:

The need to obtain mechanical properties in welded joints commensurate with those of the parent metal requires well assessed Welding Procedure Specification (WPS) including choice of welding electrode. This paper investigated the effects of electrode coating on mechanical properties (yield strength, tensile strength, ductility and toughness) of structural steel welded joints. ASTM A53B and ASTM A106B steels were welded with electrodes of different coatings and the welded joints subjected to mechanical tests at 30oC. There is a definite influence of the electrode coating on the final microstructure of the Weld Metal (WM). The study found that electrodes with cellulose coating produced welded metals with higher tensile strengths than the parent metals but the % elongation of the welded metals decreased (from 32 to 26.5 for steel type A); also the higher the basicity of the electrode coating, the higher the combination of mechanical properties. This is explained as the product of macro- and micro-reactions between the slag and the molten weld metal; and the shielding effectiveness provided by the slag over the molten metal to minimize ambient incursion/reaction with the molten weld pool. The study further established that the coating composition influences the ageing stability of the WM mechanical properties. The presence of Si (0.3%) in the base metal did little to enhance the ductility of the WM. The observed WM embrittlement with cellulose type electrode is probably a consequence of the reducing gas action evolved during combustion.