Effects of Ti-bearing inclusions on the microstructure and mechanical properties of MAG multilayer weld metal

The metal active gas （MAG） multilayer weld metal consists of the columnar grain zone （CGZ） and the fine grain zone （FGZ）. Mechanical properties and microstructure of the CGZ and FGZ have been analyzed and evaluated. The inclusion with a size of 0.2-1.0 μm is typical log-normal distribution. The morphology of inclusions has been analyzed using transmission electron microscope （TEM）. With the microalloying element Ti addition, much MnTiO3 phase precipitates on the Mn-silicates matrix, which is beneficial for the nucleation of acicular ferrite （AF）. The probable mechanism for the nucleation of AF has been discussed.