Abstract
In an oxidizing gas welding atmosphere of Ar-CO2-O2 gas mixture, mechanical properties of steel weld metal such as ultimate tensile strength and Charpy impact property have been investigated, using a popular Fe-Si-Mn electrode wire (YGW 12) and rolled steel for welded structure (SM 400B). The diagrams of ultimate tensile strength and impact property of steel weld metal have been produced as the function of the ternary welding atmosphere of Ar-CO2-O2. The ultimate tensile strength is high at the argon and carbon-dioxide rich gas mixture, and decreases as the partial pressure of oxygen increases. The ultimate tensile strength is governed principally by alloying content. The impact property improves at the optimum gas compositions of a little amount of oxygen and carbon-dioxide addition to argon. The impact property is controlled by a number of factors such as microstructure and non-metallic inclusion etc.
