Energy Density Optimization in Melt Pool

The energy in the melt pool depends on laser power and feed rate. If you put in too much energy, the grain becomes coarse and the material tough. With too little energy or too rapid cooling, you get porosity and cracks because the gas can't escape and hard microstructures form. You have to choose the parameters so that the pool runs calm and even. Start with the reference values you know for your material, then adjust. If the pool spatters or craters, you're too hot; if the weld wets poorly, too cold. What matters in the end is that the weld is tight and shows no cracks.