Özet:

In this work, Perform 700 steel sheets with 5-mm thickness were welded with single pulse MIG welding method with different welding currents and welding speeds. The welded specimens were subjected to tensile tests, hardness measurements and microstructural observations. According to the results, the heat input has an important role in tensile strength of the joint. The maximum tensile strength was obtained as 594.75 MPa at 140A welding current and 450 mm/min welding speed. The tensile specimens were always separated between fusion zone and heat affected zone. The heat affected zones have exhibited tempered martensitic structure. The tempering effect have increased the sizes of the martensitic structure; therefore, the hardness was considerably increased. However, the fusion zone, which was consisted of bainitic structure inside the ferrite matrix, was exhibited soft and ductile behavior. The boundary of soft fusion zone and hard heat affected zone formed the weakest point through the joint.

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