Effect of nano oxide on microstructure and mechanical properties of low alloy high strength steel welds

Aimed at the improvement of mechanical properties for new generation iron and steel welds, a new method, oxide metallurgy was adopted. The adopted oxides were added into liquid welding pool through electrode and the effects on microstructure and mechanical properties were studied. The results showed that a large quantity of spherical complex inclusions with the mean size of 0.2~0.8 μm were found in Al₂O₃, TiO₂ and Ce₂O₃ added weld deposits. These inclusions effectively promote the formation of acicular ferrite with mean size of 1~2 μm. The impact toughness of weld deposits increase evidently compared to that of no oxide added case, especially for TiO₂ and Ce₂O₃ added weld deposits which have impact toughness of about 150 J/cm² (-20℃), increasing by 67%.