Tailor Welded Blanks Research Articles

Characterization of Residual Stresses in Conventional Forming and Hydroforming of Tailor Welded Blanks

Characterization of Residual Stresses in Conventional Forming and Hydroforming of Tailor Welded Blanks

Investigation on the formability of friction stir welded Al-TWB through incremental forming

In the quest for weight reduction, automobile industries introduced the technology of tailor welded blanks (TWB) which offered utilization of material as per functional requirement. In general, friction stir welding (FSW) is mostly used for fabricating aluminum based TWBs as fusion welding of Al—alloys are problematic. Recently, single point incremental forming (SPIF) gained popularity among researchers as well as in industry as a dieless flexible forming technique. Hence, in this study two aluminum sheets namely AA6061 and AA7075 of similar thickness were welded together using FSW with square pin. The formability of the TWBs were evaluated in terms of cup height, wall angle and fracture location through SPIF incorporating different tool geometries. To assess the effect of weld, similar welded Al blanks were also deformed in the similar condition. The formability of the similar welded blanks and corresponding parent metals did not differ much and fracture did not initiate at the weld. However, cup depth for the TWB was in between the cup heights of the parent metals and failure was not observed at the weld region. TWB cups did not show any weldline shift.

Neural Network-Based Multi-Objective Optimization of Adjustable Drawbead Movement for Deep Drawing of Tailor-Welded Blanks.

To improve the formability in the deep drawing of tailor-welded blanks, an adjustable drawbead was introduced. Drawbead movement was obtained using the multi-objective optimization of the conflicting objective functions of the fracture and centerline deviation simultaneously. Finite element simulations of the deep drawing processes were conducted to generate observations for optimization. The response surface method and artificial neural network were used to determine the relationship between variables and objective functions; the procedure was applied to a circular cup drawing of the tailor-welded dual-phase steel blank. The results showed that the artificial neural network had better prediction capability and accuracy than the response surface method. Additionally, the non-dominated sorting-based genetic algorithm (NSGA-II) could effectively determine the optima. The adjustable drawbead with the optimized movement was confirmed as an efficient and effective solution for improving the formability of the deep drawing of tailor-welded blanks.

Control of defects in the deep drawing of tailor-welded blanks for complex-shape automotive panel

With the development of lightweight vehicles, tailor-welded blanks (TWBs) are being increasingly used in the automotive industry. Splitting and wrinkling are the main defects occurring during the deep drawing of TWBs. Accordingly, in this paper, a new method to control the forming defects is introduced in the forming process of TWBs. The microstructure and mechanical properties of TWBs are characterised by metallography and tensile tests. Finite element analysis is conducted for an automobile rear door inner panel made of TWBs to analyse the deep drawing. Edge and notch cutting are introduced to address forming defects and reduce the number of stamping tools. The thinning index, thickening index and minimum distance between the material draw-in and trimming lines are defined as the measurable index to analyse the numerical results. Orthogonal experiments, numerical simulations and multiobjective experiments are conducted to optimise the forming parameters. The proposed method and optimised parameters are verified through experiments, the results of which are essentially consistent with the numerical simulation. Indeed, the proposed method can provide guidance in controlling defects associated with the deep drawing of TWBs for complex-shape automotive panels.

Recent advancements in tailor welded blanks

A tailor welded blank (TWB) have been consistently used for manufacturing of car bodies worldwide. TWB is a blank in which different sheets of metal with various thicknesses are welded together. The main aim of this is to reduce the total mass of the vehicle which in turn improves the fuel efficiency of the vehicle, power requirements and good crashworthiness by replacing the conventional metallic blanks by TWB, which is extensively used in automobile industries. The main objective this paper is to provide the latest innovations carried in this field which will be further used in body in white (BIW) of vehicles.

A Systematic Study on the Effects of Process Parameters on Spinning of Thin-Walled Curved Surface Parts With 2195 Al-Li Alloy Tailor Welded Blanks Produced by FSW

The manufacturing process is inevitably accompanied with the production of scraps, which leads to resource waste and environmental pollution. Recycling and remanufacturing are the most commonly used approaches for metal scraps due to their well-established advantages from economic and environmental perspectives. In this study, spinning experiments with 2195 Al-Li alloy tailor welded blanks produced by friction stir welding from metal scraps were conducted under different process parameter designs. And then the effects of various process parameters on spinning of thin-walled curved surface parts were systematically studied. The results of the corresponding experimental groups show that the roller attack angle, the spinning clearance, and the installation method of tailor welded blanks have the most significant effect on the weld torsion angle. In addition, it was found that along the longitude direction of spun parts, the surface roughnesses of the weld of spun parts were greatly improved under the roller nose radius of 10 mm, the spinning clearance of 1.0 mm, the constant linear velocity, and the installation method of tailor welded blanks (the lower surface of tailor welded blanks is spun by rollers), while the process parameters have little significant effect on the surface roughness along the latitude direction of spun parts. Furthermore, it can be concluded that the forming profiles of spun parts fitted the mandrel well under the roller nose radius of 6 mm, double rollers, the roller attack angle of 30° and 45°, spinning clearance of 1.5 mm, and the installation method of tailor welded blanks (the upper surface of tailor welded blanks is spun by rollers). The research results will provide guidance for the precise spinning of thin-walled curved surface parts with tailor welded blanks. Thereby, it is also beneficial for green manufacturing involving recycling and remanufacturing of metal scraps.

Experimental investigation of tailor welded blanks of dissimilar aluminum alloys

Tailor Welded Blanks (TWBs) are now-a-days being used in many vehicles due to its advantage of reduced vehicle weight. In the decades from year 1990 to 2010, TWBs manufactured of high-strength steel alloys were the focus of the researchers' research. After year 2010 onwards, the focus of automotive industry shifted towards use of aluminum alloys and resulted in more research work related to welding process of aluminum alloys. In this research work, Friction Stir Welding (FSW) is used to join aluminum alloys AA6061-T6 and AA5052-H32. Process parameters of FSW i.e. Spindle Speed (N), Shoulder Dia. (SD) and Feed (f) are optimized by Response Surface Method (RSM) approach. Output parameters like Ultimate Yield Strength (UTS) and % Elongation are considered. Multi-objective optimization by RSM approach suggests that shoulder diameter = 16 mm, spindle speed = 1500 rpm and feed = 40 mm/min are optimum results obtained and when kept at this level will provide UTS in the range of 160 MPa-180 MPa and 10 % to 11 % elongation can be expected for friction-stir-welded blanks.

Evaluasi Kekuatan Resistance Spot Welding pada Proses Tailor welded blankss Menggunakan Mill-steel Beda Ketebalan

This paper presented the test of cup drawing, and the tensile ability of tailor welded blanks (TWBs) used to join the resistance spot welding a variety of different parameters. This study used SPCC-SD (JIS 3141) material with a material thickness of 1.0 mm and 1.2 mm. This research is focused on obtaining the highest tensile-shear strength of resistance spot welding and how it affects the results of the drawing cup process. This study used an experimental research method using six samples of RSW parameters. RSW parameters used are welding current, welding time, and squeeze time. This research was achieved the highest tensile-shear strength value of 5.09 kN and the lowest 4.15 kN which was achieved in the 5th and 1st samples respectively. The results of the cup drawing test using RSW parameters in the 5th and 6th samples showed no TWB failure in the welded area. Further research will be carried out by performing Taguchi optimization using RSW and TWBs parameters in the cup drawing process.

Al Alloy Tailor-Welded Blanks Fabrication via Friction Stir Welding: Effect of Shoulder Size

Abstract Material flow and heat generation by tool shoulder during Friction Stir Welding (FSW) significantly alters the microstructural and thermomechanical behavior of joints. The effect of shoulder size on mechanical properties of joints has not yet been reported in the FSW of Tailor-Welded Blanks (TWBs). This article reports the effect of shoulder size on joint quality in FSW of TWBs between 6.35 mm thick plates of AA2024-T3 and 2.5 mm thick plates of AA7475-T7 alloys in butt joint configuration fabricated under shoulder sizes: 18 mm, 20 mm, and 22 mm. Microstructural evaluation of FSWed joints reveals a significant increase in grain size with shoulder size. The X-ray energy-dispersive spectroscopic (EDS) elemental maps reveal the presence of fine second phase particles in the stir zone. The progressive elimination of void defects with the increase in shoulder size was observed. The tensile testing reveals the highest strength of joints fabricated via shoulder size of 18 mm. Fractographic analyses of broken tensile specimens showed the mixed mode of failure in all the welded specimens.

Cold forming of Al-5251 and Al-6082 tailored welded blanks manufactured by laser and electron beam welding

This work demonstrates applicability of electron beam welding (EBW) and laser beam welding (LBW) techniques for manufacture of tailored welded blanks (TWBs) from Al-5251 (H22) and Al-6082 (T6) sheets. A combination of dissimilar sheets as well as thicknesses (1.5 mm and 2.5 mm) has been used in addition to a similar combination. An optimal post-weld heat treatment (PWHT) was determined that was effective in relieving stresses and impart adequate ductility in the TWBs allowing cold forming (i.e. stamping), into a cruciform geometry, at ambient temperature. Pull tests revealed marked improvement in elongation for all the welds, including all combinations, after PWHT. Micro-hardness mapping of the weld sections showed transition from a non-uniform to a more uniform distribution via slight increase in hardness of the weld region whilst decrease in the hardness of the parent materials. Non-contact optical measurement using GOM camera showed minimal localised thinning in steep angled areas of the cruciform geometry. The dissimilar LBW TWBs, after PWHT, showed noticeable increase in elongation, homogeneous hardness distribution and slightly refined microstructure in the fusion zone (FZ) compared to their EBW counterparts.

A different attempt to improve the formability of aluminum tailor welded blanks (TWB) produced by the FSW

A different attempt to improve the formability of aluminum tailor welded blanks (TWB) produced by the FSW

Fracture Response in Hot-Stamped Tailor-Welded Blanks of Ductibor® 500-AS and Usibor® 1500-AS: Experiments and Modelling

Hot-stamped tailor-welded blanks (TWBs) comprised of steel sheets with different chemical compositions are of interest within the automotive sector to enhance the crash performance of vehicles via imparting local ductile regions to ultra-high strength structural components. This study examines the fracture behavior of hot-stamped TWBs composed of mono- and multi-gauge laser-welded sheets of Ductibor® 500-AS and Usibor® 1500-AS, which are under consideration for use in crash-safety members. Microstructural and microhardness investigations were conducted across the weld line of the TWBs to address the variations of mechanical properties. A fracture characterization campaign via a series of coupon tests, including uniaxial tension, equibiaxial tension Nakazima dome, and V-bend, was conducted on specimens with a range of orientations of the weld line with respect to the loading direction. Numerical models of the tensile and Nakazima dome tests with and without considering the weld region in the TWBs were developed using the LS-DYNA finite-element method software based on mapping constitutive properties and fracture-limit curves across the weld and in parent metals as functions of local hardness. The fracture characterization tests revealed that weld fracture occurred only in the V-bend tests for which the weld line was parallel to the punch (0° V-bend), while in all of the other mechanical tests considered, fracture was initiated in one of the parent metals. The Ductibor® 500-AS region was the site of fracture initiation in the transversely-welded tensile and centrally-welded Nakazima dome samples, whereas fracture initiation occurred in the Usibor® 1500-AS region for the longitudinally-welded tensile and 45° and 90° V-bend samples. The predictions revealed that the inclusion of the narrow weld region of the laser-welded blanks within the hardness-mapped TWB models resulted in an improvement of the predictions in terms of the load–displacement response and fracture locations compared to the “without weld” scenario. Therefore, the correlation of variations in the flow and fracture response of the hot-stamped TWBs of Ductibor® 500-AS and Usibor® 1500-AS with the trend of changes in hardness across the weld can be a more suitable strategy for modelling the mechanical behavior of such TWBs in crash-safety simulations.

A mean-field homogenization approach to predict fracture in as-quenched microstructures of Ductibor® 500-AS steel: characterization and modelling

Ductibor® 500-AS is a hot-stamping steel that has been designed to introduce local ductile regions within hot-stamped tailor-welded blanks (TWBs) used for energy-absorbing sections of automotive structures. This study investigates the flow and fracture behavior of a range of the microstructures of this alloy, corresponding to mostly ferritic (~96% ferrite plus 4% martensite), intermediate ferritic + martensitic (~57% ferrite plus 43% martensite), and mostly martensitic (~10% ferrite plus 90% martensite), obtained by applying various quench rates after austenitization. A series of mechanical tests in various stress states, ranging from simple shear to biaxial tension, was performed to characterize fracture for the developed microstructures. A mean-field homogenization (MFH) technique was then used to predict the flow and fracture response as a function of the microstructure. An MFH scheme designated as the interpolative Samadian-Butcher-Worswick 1 (INSBW1) within the first-order secant-based linearization method was considered to predict the macroscopic hardening behavior of the ferritic-martensitic microstructures. In the MFH modelling, the flow response of the ferritic and martensitic phases was modelled based on a dislocation-based hardening model, taking into account the chemical composition, carbon partitioning between phases, and dislocation generation and annihilation. Damage accumulation and the onset of fracture were predicted using a phenomenological damage indicator defined within each constituent phase given their calculated fracture loci and instantaneous stress and strain states. The experimental results showed that the mostly-martensitic microstructure had the lowest ductility and highest strength, and ductility and strength increased and decreased, respectively, as the martensite volume fraction in the microstructure decreased. The predicted flow curves and fracture strains as well as the fracture-limit curves for all of the microstructures agreed well with the measured data and interpolated modified Mohr-Coulomb (MMC) fracture loci.

∝-Ferrite Suppression during Fiber Laser Welding of Al-Si Coated 22MnB5 Press-Hardened Steel

During laser welding of an Al-Si coated 22MnB5 steel to produce tailor-welded blanks, the Al-Si coating mixes into the weld and causes the formation of the lower strength ferrite phase dispersed in an otherwise martensitic matrix. It has been shown that the presence of the ferrite phase is the principal reason for premature failure of hot-stamped laser-welded joints. Currently, the Al-Si coating is removed prior to welding, which can be time consuming. This work showed that adding Ni to the fusion zone of laser welded Al-Si coated 22MnB5 steel by welding through a pure Ni coating of a specified thickness, ferrite formation can be suppressed, whereby improving the weld strength and successfully shifting failure from the fusion zone, where it normally occurs, to the base material to achieve 100%joint strength. This work also showed that laser welding Al-Si coated 22MnB5 steel through a Ni coating eliminated the need to mechanically or chemically remove the Al-Si coating prior to welding.

Influence of FSW Process Parameters on Formability and Mechanical Properties of Tailor Welded Blanks AA6082-T6 and AA5083-O Using RSM with GRA-PCA Approach

Influence of FSW Process Parameters on Formability and Mechanical Properties of Tailor Welded Blanks AA6082-T6 and AA5083-O Using RSM with GRA-PCA Approach

Investigation of the Thickness Differential on the Formability of Aluminum Tailor Welded Blanks

A finite element model is proposed to investigate the effect of thickness differential on Limiting Dome Height (LDH) testing of aluminum tailor-welded blanks. The numerical model is validated via comparison of the equivalent plastic strain and displacement distribution between the simulation results and the experimental data. The normalized equivalent plastic strain and normalized LDH values are proposed as a means of quantifying the influence of thickness differential for a variety of different ratios. Increasing thickness differential was found to decrease the normalized equivalent plastic strain and normalized LDH values, this providing an evaluation of blank formability.

A novel method for the welding of tailor-welded blanks with different thicknesses based on the diode laser source

Due to weld defects occurred in the traditional laser welding of tailor-welded blanks with different thicknesses, a novel processing method is proposed in this paper. In this method, thin and thick metal plates are obliquely cut and then butt jointed to form an eave-like structure. When a laser beam irradiates on the marginal area of the thick plate, the molten metal flows into the gap and welds two plates together. Using this method, stainless steel tailor-welded blanks with a plate thickness combination of 2.0 mm and 1.0 mm are successfully welded by a diode laser source, and welded samples are free from cracks and pores. This method supplies a concise and quick processing way for the processing of tailor-welded blanks in industry.

Some Formability Aspects of High Strength Steel and of Consisting Tailor Welded Blanks

Abstract In recent years, the demand for a reduction in pollutant emission has become extremely important in the vehicle industry. It can be achieved through fuel consumption reduction, which is a direct function of the vehicle’s weight. nowadays weight is widely controlled by the use of advanced- and ultra-high strength steels (AHSS and UHSS) in vehicle body construction. With the application of such steel sheets as chassis elements, crashworthiness can be maintained next to reduced sheet thicknesses, too. In this paper, the deep-drawability and springback after V-die bending is monitored for three types of AHSS grades, namely DP600, DP800 and DP1000 materials. The investigations are extended to tailor welded blanks (TWBs), made by the aforementioned steels coupled with a cold rolled steel sheet (DC04). Our results show that deep-drawability reduces with both the increase in strength and the increase in strength difference between the components in the TWBs. Furthermore, the higher strength is shown to cause higher spring-back. The TWBs have unique spring-back behavior around the weld line.

Effect of friction stir welding parameters on the deep drawing of tailor-welded blanks (TWBs)

Friction stir welding is a method for joining dissimilar sheets and producing tailor-welded blanks (TWBs). An important issue in TWBs is their formability, as the material properties is not uniform across the welding line. In this method, the mechanical properties changing is a function of welding parameters such as traverse speed, rotational speed, and the shape of the tool. A common issue is choosing proper friction welding parameters to achieve the appropriate forming properties of the welded blanks. So in this paper, TWBs of AA2024-T3 and AA7075-T6 aluminum were prepared and welded using friction stir welding (FSW) method under various conditions, including three different tool shapes as conical, cylindrical, and square under various traverse speeds and rotational speeds. Tensile tests were carried out in order to obtain the best tensile strength conditions that are acceptable for deep drawing. The deep drawing procedure was simulated by using finite element method (FEM) to investigate the effect of weld line properties on thickness distribution and weld line movement. To verify the simulation results, the best joint was subjected to the deep-drawing process and its thickness distribution and welding line movement were compared with the simulation result. The simulation results revealed that the joint made with circular pin obtain gives the best results in deep drawing in terms of thickness distribution and weld line movement.

Experimental and numerical studies on the influence of formability of AISI 316L tailor-welded blanks at different weld line orientations

The manufacturing industries are keen on understanding the effect of weld line orientation on the formability characteristics of tailor-welded blanks (TWBs) with sheets for the design and manufacture of structures with lightweight. The AISI 316L sheets of 2 mm and 1.6 mm were welded together by cold metal transfer (CMT) process using a welding current of 95 Amperes and a welding speed of 350 mm/min to fabricate TWBs. Two different TWBs were made with the welding line parallel to the rolling direction RD (WL||RD) and the weld line perpendicular to the RD (WL⊥RD). The quality of the TWBs was evaluated by microstructural examination, mechanical integrity by tensile, hardness and Erichsen cupping test with laboratory-scale specimens. The engineering stress–strain plot and formability characteristics of the TWBs were considerably influenced by the weld line orientation with respect to the RD. It was noticed that the formability of TWBs decreased slightly compared to the base metal (BM) and fracture appeared in the thinner region (1.6 mm side), away from the weld line. Finite element (FE) prediction of Erichsen cup height was performed with ABAQUS software considering the weld metal properties. FE analysis using Johnson–Cook damage criterion predicted a cupping height that showed good coherence with experimental measurements for BM and TWBs with an error percentage less than 5. The stress distribution was non-uniform in the deformed TWBs with more stretching, and the magnitude of deformation was higher in the thinner region.