1992 Volume 10 Issue 2 Pages 264-271
As shown in the previous papers, not only high deposition rate but also low oxygen weld metal without any defects could be obtained by the AC-MIG welding process. To clarify the effect of oxygen content on the mechanical properties, regression analysys of the weld metal toughness, thermal analysys of the transformation during welding and examination of the oxide inclusion have been conducted in this study.
Main results are as follows.
Good correlation between the vTrs, the oxygen content and the tensile strength was existed. And the vTrs became lower than -90°C at the optimized oxygen content of 150 ppm and the tensile strength of 65-70 Kgf/mm2.
There was a suitable transformation temperature and its range for the toughness. This meant high toughness could be achieved by the homogeneous fine acicular ferrite structure transformed intra- and interganulary at a certain temperature simultaneously.
Fine oxide particles contained Ti at higher oxygen content than 120 ppm, and fine acicular ferrites were nucleated.
