Theoretical Weld Metal Dilution
The percentage ratio of the melted base metal to the total cross-section of the weld bead. It directly influences the final chemical composition and mechanical property profile of the weld metal.
Dilution tells you how much base material is melted into the weld relative to the filler material. That ultimately determines the mix and thus the properties of the weld. If you melt too deep, you have too much base material in there, the structure becomes coarse and the weld tough. If you weld too flat, you can get fusion issues. You need to keep an eye on heat input and travel speed. Depending on the base material and requirements, you want to keep the dilution rate low, for example with cladding or when you're laying a highly alloyed filler on unalloyed steel. Then a thin layer is often enough, and you run multiple layers instead of burning deep.