Influence of the Welding Angle on the Mechanical Behavior of Plates obtained by the Tailor Welded Blank (TWB) Process

Tailor Welded Blank (TWB) is a top-welding technique (by unconventional processes) of sheets of different specifications (materials, thicknesses and/or coatings). Because it allows localised distribution of mechanical properties and mass, it can optimise the relationship between structural rigidity and total weight. The great challenge of this technique is to combine two processes with completely different demands, welding and mechanical forming. This work investigates the mechanical behavior of sheets obtained by the Tailor-blank process from the determination of the optimum angle. We performed tensile tests on sheets with different weld line inclinations, as the general objective is to consolidate knowledge about the process, characterise the conditions for sheet formation obtained by the technique, in a safe conformation range, with complex contours, dimensional qualities and free of catastrophic failure. Steel sheets, interstitial free (IF), of 1.10mm and 0.65mm thick were used. The TWB was applied with a welding line oriented from 0º to 90º (ranging from 15° to 15°). The optimum angle obtained was 30º, where there was a good relationship between the breaking load, purely tensile and shear stresses, and the total elongation. In relation to the angle of 0º, the optimum angle presented a superior elongation of approximately 40%. It was still possible to notice that the thickness of the plates influenced the optimum angle, even if the LSR (Limit Strength Ratio) is close.

Formability study and metallurgical properties analysis of FSWed AA 6061 blank by the SPIF process

In this study, in order to obtain the maximum possible formability in tailor-welded blank AA6061 sheets connected by the friction stir welding (FSW) procedure, the incremental sheet forming process has been utilized. The results are presented both numerically and experimentally. To obtain the forming limit angle, the base and FSWed sheets were formed in different angles with conical geometry, and ultimately, the forming limit angle for the base metal and FSWed sheet is estimated to be 60° and 57.5°, respectively. To explore the effects of welding and forming procedures on AA6061 sheets, experimental studies such as mechanical properties, microstructure and fracture analysis are carried out on the samples. Also, the thickness distribution of the samples is studied to investigate the effect of the welding process on the thickness distribution. Then, the numerical process was simulated by the ABAQUS commercial software to study the causes of the FSWed samples failure through analyzing the thickness distribution parameter, and major and minor strains and the strain distribution. Causes of failure in FSWed samples include increased minor strain, strain distribution and thickness distribution in welded areas, especially in the proximity of the base metal area.

Finite and Numerical Simulations Applied in Tailor Welded Blank

The increase in economic and technological competitiveness means that the automobile industry seeks constant innovation in its production methods and processes, in order to produce lighter, safer and more efficient vehicles. Products with greater mechanical resistance, better conformability, thickness combinations of plates / materials are sought with a focus on reducing mass and increasing the rigidity of the vehicle body. In this scenario, Tailor Welded Blank (TWB), which is a top welding technique (by unconventional processes) of sheets of different specifications (materials, thicknesses and / or coatings), appears as a solution, as it allows localized distribution of mechanical properties, mass, optimizing the relationship between structural rigidity and the total weight of the vehicle body. The great challenge of this technique is to combine two processes with completely different demands, welding and mechanical forming. Due to the complexity of forming TWBs, the use of simulations has been widely adopted. In this review, different results of the numerical simulation methods used for a Tailor Welded Blank are compared, focusing on the details and the influence of the parameters used.