The paper deals with the numerical simulation and experimental investigations of a buried-arc welding process on a butt-welded plate sample. In the numerical investigations, the finite element analysis is carried out by applying the element birth and death technique in the thermal analysis, while the mechanical analysis is performed simultaneously in one step to reduce simulation time. The temperature history at two locations is recorded with thermocouples, while residual stresses are measured by using the hole-drilling stress relaxation method at four points. The heat input efficiency for the buried-arc welding process is determined by using a parametric analysis. The numerically obtained temperatures and residual stresses correspond very well with the experimental measurements. Furthermore, by using buried-arc welding, 73% of the weld filler material is saved and 59% of energy, whereas the CO2 emission to the atmosphere is reduced by 83% in comparison with conventional metal active gas welding for a model of the same dimensions.