The grain size is an important parameter influencing not only the material brittleness and strength properties, but also the transformation processes of creep, strength, and fatigue. This present paper is therefore focused on the process description for the experimental determination of the kinetics of grain growth curves temperature dependence. These curves are then used for numerical simulations of grain coarsening in different technological applications such as welding, heat treatment, or slow cooling of large parts. Further it will be demonstrated how obtained curves can be used for the prediction of the grain size in the heat affected zone (HAZ) of multilayer heterogeneous welds of X10CrWMoVNb9-2 and 18Cr9Ni3CuNbN materials and subsequently verified by real welding experiments. The paper will also show the main benefits of using GLEEBLE simulator for verification of the grain coarsening in HAZ of realized welds.