Avtomaticheskaya Svarka (Automatic Welding), #1, 2020, pp.15-24
Impact of spatial position in laser welding on quality level of welded joints of AISI 321 steel
A.V. Bernatskii, V.D. Shelyagin, O.V. Siora, V.M. Sydorets, O.M. Berdnikova
E.O. Paton Electric Welding Institute of the NAS of Ukraine, 11 Kazymyr Malevych Str., 03150, Kyiv, Ukraine.
The objective of the study was determination of the impact of spatial position in laser welding of corrosion-resistant austenitic steel AISI 321 on the microstructure and quality level of welded joints. Penetration beads were made in plates of 3 mm thickness at different angles of inclination to the horizontal plane. «Uphill» and «downhill» laser welding was performed both in the continuous and pulse modes of laser radiation generation. Results of visual and radiographic testing and analysis of the data of metallographic studies were used for assessment of quality level of the produced samples for compliance with the requirements of valid standards. In «uphill» and «downhill» welding in the continuous mode of laser radiation generation no internal defects in the form of cracks, pores and inclusions were found at all the angles of inclination. A tendency to increase of both the quantity and size of pores at reduction of the angle of inclination from 90 to 0 deg was found in «downhill» and «uphill» welding in the pulse mode of laser radiation generation. By the data of metallographic studies, no significant differences were observed in the structure of welded joints made in different spatial positions on steel AISI 321 3 mm thick. At different values of the angle of inclination, the microhardness and dimensions of the crystallites differ by approximately 10 %. Contrarily, the shape of welds in the produced penetration beads differs quite significantly. Dependencies of quality characteristics of welded joints of AISI 321 steel in laser welding were derived for the first time for different spatial positions. Derived dependencies allow determination of the tendencies of the change of the shape and quality of welded joints at the change of position or technological parameters of laser welding process. 13 Ref., 2 Tabl., 6 Fig.
Keywords: laser welding; corrosion-resistant steel; heat-resistant steel; austenitic steel; technological parameters; spatial position; quality; structure; porosity
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