Root Dilution Rate
Root fusion degree indicates how much of the base material is fused in the root pass. It influences the chemical composition and microstructure of the first weld layer.
Physico-chemical mechanism of action
The root penetration rate describes the extent of the melted base material near the root. This degree influences the diffusion of alloying elements and the buildup behavior of the microstructure.
Metallurgical relevance & welding risks
Too high a root penetration rate can lead to an excessive concentration of alloying elements, causing coarsening and reduced mechanical properties of the weld. Too low a rate can result in insufficient diffusion and lack of alloying element introduction, which reduces hardness and toughness.
Workshop practice & action instructions
To optimize the root penetration rate, pay attention to correct welding temperature and sufficient melting time. For heavy alloying elements (such as silicon or molybdenum), slower cooling is required to ensure homogeneous diffusion.