This study evaluated the mechanical joining characteristics of substrate Al7075 using the filler metals of ER5356 and Al7075 to secure the joining integrity of the specimens by GTAW. The results of radiographic test show that the welded specimens meet the first level standard of KS D 2042. Besides, welding defects were not occurred. The tensile strengths of the specimens using the filler metals of Al7075 and ER5356 had 240MPa and 252MPa, respectively. The yield strengths were 132MPa and 120MPa, respectively. In case of using the filler metal of Al7075, However, in case of using the filler metal of ER5356, Two filler metals of Al7075 and ER5356 were similar to each other in tensile and yield strength.

The purpose of this study is to research into which characteristic is shown according to a change in filler metal in case of CO2 gas arc welding by using Automobile Structural Steel(ATOS80). The major characteristics of this study were experimented by having Bevel angle as 50°, Root gap as 3mm, Filler metal as Solid wire & Flux wire, and the projected length of wire as 15mm. This study made the welded test specimens for the KS specification in advance suitably for the conditions, thereby having comparatively analyzed with the data value that was obtained through tensile test, hardness test, impact test and Macro Structure Detecting. Arranging the results that analyzed finally, the tensile strength and the hardness appeared to be excellent in case of welding with flux wire. The impact strength was indicated to be superior in case of welding with solid wire.