Mohammad Reza Dianati - MS Student, Department of Materials Engineering, Tarbiat modares University, Tehran, Iran,
Farshid Malek Ghaeni - assistant professor, Department of Materials Engineering, Tarbiat modares University, Tehran, Iran,

In this study, the similar joint bonding of ۴۳۰ stainless steel thin sheet was investigated using microplasma welding as this method has a high arc energy density, good arc stability, deep penetration, high metallurgical purity, and low heat affected area. For this purpose, two thin sheets of ۴۳۰ steel with a thickness of ۰.۳ mm were butt welded. Then, the resulting microstructure and macrostructure were examined using a microscope and stereo microscope respectively. Afterward, microhardness test was performed. Examination of the resulting microstructure showed that by approaching the weld area (from the base metal), the grains became coarser and also martensite was deposited between the grains, which increased the hardness in the area affected by heat and welding, and consequently reduced the toughness. Examination of the macrostructure also showed that the molten metal grains of the weld pool grew epitaxially in directcontact with the base metal grains. Keywords: Microplasma welding, ferritic

Microplasma welding, ferritic stainless steel, butt welding, thin sheet, microstructure.