Caracterización metalográfica y evaluación del perfil de dureza en una junta soldada mediante proceso de soldadura por fricción rotacional en aceros inoxidables austeníticos, martensíticos y acero al cromo

Abstract

The objective of this work was to carry out the metallographic characterization and evaluation of the hardness profile in a welded joint by rotational friction welding process in austenitic, martensitic and chrome steel stainless steels. The welding process was carried out in a common lathe that reaches a minimum of 2000 rpm, the emergency brake must be enabled to stop the system and avoid cutting by friction. The steels were welded in two groups: between their own denomination and combined with each other, the specimens in both cases by turning in a CNC tone were lowered 2 mm to avoid contaminants and in the same machine they were machined so that their geometries are compatible with clamping mechanisms. Variables such as speed of revolution, heating time, forging time and axial displacement were modified until they ensured the best joint quality. Once the specimens had cooled following the visual inspection parameters of the AWS, the specimens that presented discontinuities, incomplete fusion, off-centering, and separation in the joints were discarded. In the approved specimens, after being cut and polished, it was possible to identify the zones affected by heat in which the microstructure was identified, in addition, the hardness of these zones was determined, with which a hardness profile was made. The microstructures of similar welds did not change aggressively, in the case of dissimilar welds the Schaeffler diagram will predict and confirm the microstructure of the mixing zone. It is concluded that the welds where steels with martensitic microstructure are found will be much harder than those with austenite. It is recommended to automate the process, since the human factor is related to most failures in the joint finish.