EXPERIMENTAL STUDY ON MECHANICAL PROPERTIES AND MICROSTRUCTURES IN A 36 REPAIR BUTT WELDMENT

Welding is one of the usual assembling methods with various applications. The
different defects are generated during welding and also in service conditions. After inspection and
identifying the defects, the repairs are applied. Welding repair operation causes the mechanical
properties and the microstructures of weldment to change. In the present work the variations of
yield stress, hardness and microstructures in the A 36 repair butt specimens were investigated by
the experimental study. The welding technique was Tungsten Insert Gas method without using
filler. The specimens were cut from the welded plates using water jet method for avoiding heat
effect during the cutting. The low-carbon steel A 36 thin plate was used to construct the
specimens. This material has numerous applications to construct various structures and parts. The
specifications of specimens and tests were selected according to the standards. The tensile tests
were performed for four numbers of each specimen. The mean of yield stresses in the specimens
were reduced after the repairing through half- thickness of the butt welds. Moreover, the mean of
yield stresses in the specimens after repairing would be decreased if the welding voltage and
current increased. Reduction of the hardness in heat affected zone and variation of the phases and
grain size after repairing were other outcomes from testing on the specimens.