Oxygen inclusion morphology
The geometric formation and distribution of oxidic inclusions caused by residual oxygen in the microstructure. This morphology significantly influences the anisotropy of mechanical properties.
Oxide inclusions form when the oxygen in the weld pool isn't properly bound. This usually happens with too little shielding gas or when the material is dirty. The result is small oxides in the structure that make the material brittle and reduce toughness. To avoid this, you need to keep the weld pool clean: set the shielding gas correctly, grind off scale and rust beforehand, and if necessary, use a wire with deoxidizers. Heat input also plays a role – if you weld too hot and slow, you get more oxidation. In the end, the cleaner the weld and the better the shielding, the fewer oxides in the structure. If you have the parameters under control, this issue is usually not a problem.