Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Experimental analysis of residual stress relief by mechanical vibration in resistance spot welding
Submission Author:
Paola Rodrigues Pereira , RJ
Co-Authors:
Paola Rodrigues Pereira, Hector Costa, DANIEL CASTELLO, Maria Cindra Fonseca
Presenter: Paola Rodrigues Pereira
doi://10.26678/ABCM.COBEM2023.COB2023-1775
Abstract
The High Strength Low Alloy steels (HSLA), such as the cold-rolled HC420LA, are mostly applied in the automotive industry, especially in vehicle bodywork. The microstructure, which has a low content of alloying elements and added carbon, allows great advantages as high tensile strength, good toughness and weldability. Resistance spot welding (RSW) is known for its rapid application, low cost and easy automation, being then commonly used in the automotive industry. Due to the combined action of shrinkage, heat input and phase transformations that occur during welding operations, residual stresses are generated in the welded joint. These are generated in all manufacturing processes and are produced when regions of a material undergo permanent heterogeneous plastic or elastic deformation, without the presence of any external loads. It is well established that tensile residual stresses have a detrimental effect, as they can add to service loads, contributing to the nucleation and propagation of fatigue cracks. Therefore, new techniques for stress relief have emerged, such as Vibration Stress Relief (VSR), which reduces residual stress through cyclic loading treatments and does not cause distortions or microstructural changes in welded joints, as may occur in heat treatments. The aim of this work was the development of an experimental analyze of the residual stress relief by the mechanical VSR method in the resistance spot welded joints of HC420LA steel. Residual stresses were analyzed by X- ray diffraction technique, by sin2psi method and were correlated to Magnetic Barkhausen Noise (MBN) measurements. This work contributes to a better understanding of VSR techniques applied on resistance spot welded joints. The residual stresses generated in spot welding was quantified and qualified before and after stress relief, and a relationship has been established among the methodologies available for their measurement.
Keywords
Residual stresses, X-ray Diffraction, Vibratory stress relief, Barkhausen noise, Resistance Spot Welding
