Efecto de la soldadura por fricción rotativa en la microdureza fatiga y microestructura en juntas soldadas de aceros al carbono e inoxidables

• Autor: Villareal Guzman, Oscar Eduardo
• Formato: tesis de grado
• Fecha de Publicación: 2019
• Institución: Universidad Nacional de Trujillo
• Repositorio: UNITRU-Tesis
• Lenguaje: español
• OAI Identifier: oai:dspace.unitru.edu.pe:20.500.14414/14630
• Enlace del recurso: https://hdl.handle.net/20.500.14414/14630
• Nivel de acceso: acceso abierto
• Materia: Soldadura, fricción rotativa, acero al carbono, acero inoxidable dúplex

A study on the mechanical properties of traction, microhardness, fatigue and microstructure in welded joints of two dissimilar steels was carried out. Carbon steel AISI 1020 and Stainless steel Duplex AISI 2205, using the processes of rotational friction welding (FRW) were joined. The purpose was to observe the behavior of these joints by combining various test parameters. The samples were made from AISI 1020 and AISI 2205 ½ ”Ø steel bars. 24 test pieces were made (2 repetitions). For tensile tests, the ASTM E-8 standard was followed, the same number of specimens were made for Fatigue and microhardness. All the specimens were made after performing FRW friction welding tests, for which, forged pressure, friction and timing measuring devices, coupled to the MHASA parallel lathe, were coupled. The process followed the direct impulse method. The parameters: Rotation speed: (1000-1400) rpm; Friction time: (4-6-8) sec; Forging time: 4 sec; Friction Pressure: (3-5) MPa Forging Pressure: 6 MPa were used. The Mechanical Resistance of the joint was measured in the TECNCTEST tensile testing machine. The microhardness profile measured longitudinally on the Vickers scale (HV). Microscopy was performed at the optical level, using the Zeiss 1000X Microscope. The microstructure of the first 4 samples tested was observed. It was found, with 1000 rpm, the highest mechanical strength values of the joint were obtained. The maximum value (692.3 MPa) is found with: [n = 1000 rpm, Tf = 8 sec, Pf = 5Mpa], giving a joint efficiency of 103% with respect to 1020 steel and 70% with respect to 2205 steel The maximum fatigue limit: (270 MPa), is presented by the P7 specimen. Then, the best welding conditions for this property were: [n = 1400 rpm, Tf = 4 sec; Mp = 3 MPa]. The specimens welded at 1000 rpm, have a fatigue limit in the range: (225-250) MPa, and those, welded at 1400 rpm within: (220-270) MPa. The microhardness in the central zone does not have a constant value. The (ZAC) on average is small ~ 2.2 mm. and the contact zone ~ 120 µm. The junction zone has severe plastic deformation, and has a fine grain structure, thickening in the deformation zone. In this FRW friction welding process, all parameters influence; variables are interdependent, and according to the case, one of them is more influential than the others.