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CorrosIon resIstanCe and meChanICal propertIes of tIG and a-tIG welded joInts of lean duplex staInless steel s82441 / 1.4662This paper presents results of pitting corrosion resistance of TIG (autogenous and with filler metal) and a-TIG welded lean duplex stainless steel S82441/1.4662 evaluated according to aSTM G48 method, where autogenous TIG welding process was applied using different amounts of heat input and shielding gases like pure ar and ar+N2 and ar+He mixtures. The results of pitting corrosion resistance of the welded joints of lean duplex stainless steel S82441 were studied in as weld conditions and after different mechanical surface finish treatments. The results of the critical pitting temperature (CPT) determined according to aSTM G48 at temperatures of 15, 25 and 35°C were presented. Three different surface treatment after welding were applied: etching, milling, brushing + etching. The influence of post weld surface treatment was studied in respect to the pitting corrosion resistance, basing on CPT temperature.Research on TIG welding of lean duplex stainless steel S82441/1.4662 showed a clear influence of the applied shielding gas mixtures, where the addition of 5 to 15% N2 to ar virtually no effect on the level of resistance to pitting corrosion, only 5% N2 addition has a positive effect, while use of a mixture of 50% ar + 50% He compared with welding at 100% ar atmosphere, can significantly reduce the resistance to pitting corrosion. Definite good results were obtained during TIG welding with the participation of activation flux (a-TIG). The weld surface of lean duplex stainless S82441/1.4662 obtained in a-TIG welding without the addition of filler metal has a much lower tendency to pitting corrosion than traditional welds made by TIG method. Pitting corrosion resistance of welds made by a-TIG improved with the increase of the heat input in the tested range of welding current 100-200 a. It was also found that the intensity of the occurrence of pitting does not affect the method of cleaning welds after welding, but the mechanical removal of a thin surface layer of metal significantly reduces their intensity.

This paper deals with the investigation of complex corrosion properties of 3D printed AISI 316L steel and the influence of additional heat treatment on the resulting corrosion and mechanical parameters. There was an isotonic solution used for the simulation of the human body and a diluted sulfuric acid solution for the study of intergranular corrosion damage of the tested samples. There were significant microstructural changes found for each type of heat treatment at 650 and 1050 °C, which resulted in different corrosion properties of the tested samples. There were changes of corrosion potential, corrosion rate and polarization resistance found by the potentiodynamic polarization method. With regard to these results, the most appropriate heat treatment can be applied to applications with intended use in medicine.