Papers by Keyword: LBW

Abstract: Ti-6Al-4V is an alloy that is increasingly used in aeronautics due to its high mechanical properties coupled with the lightness. An effective technology used to manufacture titanium components with a reduced buy to fly ratio is the laser beam welding. Previous studies showed that the key factor that rules the mechanical properties and the fatigue life of the joint is its morphology. The aim of this paper was to investigate the influence of the main process parameters, such as welding speed and laser power, on the geometrical features of the joint, in terms of undercut, underfill, reinforcement and so on. 3.0 mm thick Ti-6Al-4V rolled sheets were welded in butt joint configuration by using a Nd-YAG laser source. The joint performances were studied in terms of weld morphology, microstructure and Vickers microhardness. Then, defects such as underfill and reinforcement, controlling the whole weld morphology, were observed, and the relationship between the occurrence, the entity of these defects and the process parameters was studied.

Abstract: Comparative finite element method (FEM) analyses of resistant spot welding (RSW) and laser beam welding (LBW) on stainless steel railway vehicles to assembly the framework and the side wall penal were conducted. The stress and strain of RSW joint and LBW lap joint were calculated under the same loading conditions by FEM simulation, respectively. The analyses revealed that not only the stress concentration occurred but also the maximum stress existed in the RSW joint compared with LBW lap joint under the same load. In contrast, LBW technique had more advantages than that of RSW technique in joining the car body framework and side wall penal of railway vehicles in the respects such as smaller deformation, better air tightness, and better appearance of car body and higher efficiency of processing.

Abstract: In this study, the toughness of 11Cr ferritic stainless steel weld was evaluated by DBTT (Ductile-Brittle-Transition-Temperature) with the interstitial elements level. DBTT of the weld increased with increasing interstitial level due to the formation of martensite phase and solidsolution strengthening. Interstitial elements level should be limited by the adoption of back shielding gas during welding process because increased C+N level detrimentally affects the toughness of ferritic stainless weld. Adoption of Ar as back shielding gas lowered N content in the weld.