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Nd:YAG PULSED LASER APPLICATION IN WELDING OF UNS S32750 SUPERDUPLEX STAINLESS STEEL USED IN THE OIL AND NATURAL GAS INDUSTRY

Grant number: 15/12797-6
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): September 01, 2015
Effective date (End): August 31, 2017
Field of knowledge:Engineering - Mechanical Engineering - Manufacturing Processes
Principal Investigator:Vicente Afonso Ventrella
Grantee:Matheus Shimizu Clemente
Home Institution: Faculdade de Engenharia (FEIS). Universidade Estadual Paulista (UNESP). Campus de Ilha Solteira. Ilha Solteira , SP, Brazil

Abstract

In general, the essential requirements for an alloy used in industries belonging to the Oil and Gas sector are mechanical strength, in view of the various efforts to which the materials will be submitted, and corrosion resistance due to environmental severity to which the materials will be exposed. In this sense, besides the challenges of oil exploration increasingly aggressive existing sources, the new findings called pre-salt represent another group of operations that require use of high mechanical performance materials and corrosion, and also Welding processes that can guarantee good quality of the welded joint. The super duplex stainless steel is gaining more and more space in the petrochemical industry precisely because it has such requirements mentioned above. In addition, it meets the needs of austenitic and ferritic already traditional in many applications because the super duplex stainless steel is able to combine the properties of both ferritic and austenitic. Is attributed to their high resistance to corrosion and to its balanced mechanical microstructure by approximately 50% ferrite and 50% austenite. The welding the super duplex stainless steels directly affects the weld metal microstructure, and therefore, only a well-tuned welding process can generate welds with a proper balance of phases (austenite and ferrite) with minimal precipitation deletéreis intermetallic phases. If this balance is not achieved can lose the advantages of super duplex steel over traditional stainless steels. This scientific initiation research work involves the study of the influence of the energy of laser welding pulse Nd: YAG on the balance of ferrite phase / austenite stainless steel super duplex UNS S32750. Laser weld beads will be obtained with different laser beam intensities, time width (ms), and different focal depths. The results obtained through this proposed study will therefore be compared with experimental results available in the literature, which have been generated by other welding processes. Thus, the role of the laser in the control of austenite and ferrite phases will be investigated, where it is demonstrated the feasibility of using the laser welding process pulsed Nd: YAG laser in controlling the phases present in the weld metal, thus ensuring a good toughness and good corrosion resistance of the welded joint. Microstructural characterization techniques will be used by Optical Microscopy and Scanning Electron Microscopy. In addition, a mechanical characterization is performed by Vickers microhardness testing and tensile testing. The intended contribution for this undergraduate research project must be in order to achieve greater dissemination of information about the application of a laser source solid state, pulsed, Nd: YAG welding in stainless steel super duplex UNS S32750.