IDENTIFICATION AND PROPERTIES OF NONMETALLIC INCLUSIONS IN WELDED JOINTS 

Ignatov Mikhail Nikolaevich, Doctor of engineering sciences, professor, sub-department of welding fabrication and structural material technology, Perm National Research Polytechnic University (Perm, 29 Komsomolsky avenue), svarka@pstu.ru
Ignatova Anna Mikhaylovna, Candidate of engineering sciences, senior staff scientist, Perm National Research Polytechnic University (Perm, 29 Komsomolsky avenue), anutapages@gmail.ru
Kanina Aleksandra Evgenyevna, Postgraduate student, Perm National Research Polytechnic University (Perm, 29 Komsomolsky avenue), rusalka-88@mail.ru 

669.640.191

In order to identify and study the properties of non-metallic inclusions in metals the article suggests to use the methods of nanoindentation and SEM, as they provide accurate data on the inclusions of the size of less than100-50 microns and provide accurate mathematical modeling of internal stresses in the metal containing them. The article presents the study of non-metallic inclusions in the welded pipe joints. It is proved that they are not pure oxides and complex mineral phases have a complex morphology. This leads to the fact that the actual surface area increases, and differs from the theoretical 2-fold, and this significantly lowers the reliability of the calculated welded joints. It is recommended to use the obtained data for more accurate modeling and predicting the reliability of welded joints. 

welding, steel welded pipe connections, non-metallic inclusions, synthetic mineral alloys. 

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