Concerning laser welding as a manufacturing process, there are still extensive experimental tests necessary to determine the resulting product properties in order to optimize the manufacturing process and to improve the product design. A simulation of the laser welding process can contribute to supply information about achievable product properties already in the very early stages of product design and production planning. As a result, considerably more reliable planning results can be obtained, while at the same time the necessary experimental expense decreases. The aim of process simulation, based on finite element methods, is to gain information about properties relevant to product design, e.g. the geometry of the seam cross section or the distortion of the workpiece. Due to the extremely large temperature gradients within a small volume of energy absorption, it is necessary to analyze the process in two steps. In the first step, the welding process is modeled in a very detailed way within a heat transfer analysis. Already the resulting time-temperature behavior of the material provides information about microscopic properties of the weld seam, e.g. cross section geometry or hardness. Based on those results, the heat influence on the whole workpiece, e.g. residual stress and distortion, can be determined in the following second step, using a coupled thermo-mechanical analysis with a less detailed model. The results of the analysis coincide well with experimental data.