Contents of this paper are investigations of the influence of the gas metal-arc welding and the metal-active gas welding process on the properties of the weld metal of superduplex materials. It is reported about the investigations of build-up weldings with different welding- and process parameters. The composition of the shielding gas was altered after weldings with varied heat input and varied preheating temperatures have been carried out. Starting with pure Argon the portions of nitrogen, helium, carbondioxid and oxygen were increased. The weld material properties were tested by metallographic examinations, measuring the ferrite content and the hardness. Impact testing of Charpy-V-notch specimens made from the weld metal were carried out. Impact testing of KLST-specimens taken from different layers of the weld material should give information on the influence of repeated heating of the multi-layer technique. The critical pitting temperature CPT was determined in corrosion testing.