Maximum Tensile Shear Force Research Articles

Optimization and Simulation Parameters of the Resistance Spot Welding for Commercial Aluminium (AA1050) at Low Power Welding Machine

This study aims to find the best conditions of resistance spot welding in commercial Aluminium AA1050 to obtain the maximum tensile shear strength of the joint using a low-power supply welding machine. The chosen parameters for this study were welding current, welding time, and electrode force using a 90 kVA welding machine. The investigation used the DoE method with Taguchi’s technique to reduce the number of experiments where two sheet thicknesses (1 mm and 2 mm) were used in this work. The software program Minitab 18 analyzed the results using the main effects plots and the interaction plots to identify the most significant parameters and their effect on the joint strength. The best conditions for maximum tensile shear force were 14.85 kA welding current and 0.79 kN electrode force for both thicknesses and two cycles and 12 cycles welding time for 1 mm and 2 mm sheet thickness, respectively. The maximum tensile strength obtained was 250 N and 225 N for 1mm and 2mm sheet thickness, respectively. A mathematical equation was developed to predict the shear force with 19.9 % and 17.9 % error for 1 mm and 2 mm thicknesses, respectively. The best conditions were applied in ANSYS 2022R1 multi-physics to obtain the temperature distribution with time history, where the result shows the nugget size according to the molten temperature. The percentage of discrepancy between actual and numerical nugget size was 8 %.

Effect of linear heat input on the interface and mechanical properties of steel/CFRP laser welding joint

An investigation on laser joining of PA66 carbon fiber reinforced plastic (CFRP) to DP780 dual-phase steel was presented. Effect of linear heat input on the interface and mechanical properties of steel/CFRP joint was performed. When linear heat input increases, the softening phenomenon is not observed in heat-affected region of dual-phase steel. Meanwhile, the melting point and decomposition temperature of resin are less impacted. The maximum tensile-shear force of steel/CFRP joint reaches 1959.4 N. The interface temperature is contained between melting and decomposition temperature of resin, the spreading of resin on steel surface is promoted, and a favorable steel/CFRP bonding interface is obtained. In addition, the new chemical bonds such as M−C and M−O are formed, which is conducive to the chemical connection of steel/CFRP interface. However, as excessive linear heat input is applied, the interface temperature will exceed the decomposition temperature of resin, resulting the generation of decomposing pores. Moreover, due to excessive heat on resin, its crystallinity decreases, the interface between resin and fiber is weakened, so that the fracture behaves as a mixed fracture mode of interface and cohesion fractures, which deteriorates steel/CFRP joint properties.

Effects of laser power on the microstructural evolution and mechanical performance in laser dissimilar welding of TC4 to SiCp/6092Al composite

In this study, an overlap configuration for Ti6Al4V alloy (TC4) and SiC particle reinforced aluminum matrix composites (AMC) was achieved by laser welding process. The influence of laser power on the microstructural evolution, intermetallic compounds formation and mechanical properties of TC4/AMC joints were investigated. The presence of reinforced phase SiC complicated the metallurgical reaction in the molten pool, resulting in the formation of intermetallic compounds, such as Al4C3, TiC, TiAl, and TiAl3. The influence of laser power was more pronounced on the penetration depth compared to its impact on the weld width. The thickness of TiAl intermetallic compounds at the TC4/AMC interface increased as the laser power was raised. Abundant dislocations existed surrounding the TiAl3 phase because of the different thermal-mechanical properties between Al matrix and TiAl3 phase. The tensile shear force of TC4/AMC joints can be considerably improved by reducing the thickness of the TiAl3 phase. The maximum tensile shear force of 1675.6 N for the TC4/AMC joint was obtained at a laser power of 1500 W when the thickness of the TiAl3 layer reached the lowest value of 7.1 μm. The research results have the potential to improve laser welding techniques for TC4/AMC hybrid structures and provide valuable guidance for the design of TC4/AMC welded joints in the future.

Research on the influence of Welding Head using the process on Welding Performance of Spot Welding Machine

Aiming at alloys commonly used in terminals, this paper studies the method of improving the characterization performance of the spot welding section from the perspective of controlling spot welding process parameters. Using the control experiment, by controlling the welding current, energization time, electrode pressure, and using coolant during welding, the surface structure image and the maximum tensile-shear force curve were obtained, so as to obtain the optimal spot welding process parameters. Then use ANSYS finite element analysis software to simulate the resistance spot welding process, and use the model of the macro morphology, microstructure, hardness distribution, and shear resistance of the spot welding head to verify the optimal welding process parameters of resistance spot welding.

Microstructure and Mechanical Properties of Laser Welded Magnesium Alloy/Steel Joint Using Cu-Si Composite Interlayer

In this study, Cu-Si composite powder was used as the interlayer to carry out laser lap deep penetration welding of AZ31B magnesium alloy and DP590 dual-phase steel. The effects of Cu-Si composite powder on the weld formation, microstructure, and mechanical properties of magnesium alloy and steel joint were studied. The results show that the addition of Si can improve the laser absorption rate of the interlayer and increase the melting depth at the magnesium side. In addition, the Cu-Si composite interlayer hindered the diffusion of Al, and reduced the thickness of reactive layer at the magnesium alloy and the steel interface. After adding Si into the interlayer, the reactive layer changed from Fe3Al+α-Mg to Fe-(Al, Si) +α-Mg and the content of intermetallic compounds in the reactive layer decreased, which improved the plastic deformation capacity and the ductility of the reactive layer. As a result, the tensile shear force firstly increased and then decreased with the Si increase. The maximum tensile shear force of 86.2 N/mm was achieved when the Si content was 5%, which was 20.4% higher than that of the Cu interlayer. Plus, the fracture location changed from near the steel side to near the magnesium side weld.

Elucidation of intermetallic compounds and mechanical properties of dissimilar friction stir lap welded 5052 Al alloy and DP590 steel

The friction stir lap welding (FSLW) was employed to join the dissimilar 5052 Al alloy and DP590 steel. The intermetallic compound (IMC) formation area and thickness increased linearly with increasing rotation speeds at 300 mm/min welding speed. Microvoid and gap defects existed on low-rotational-speed-produced lap interfaces, disappearing with increasing rotation speeds. However, cavities defects neighbouring the large-sized steel fragment appeared in the stir zone of the Al matrix with rotation speeds higher than 750 rpm. The negative influences from the Al-rich IMCs layer exceeding 1.5 µm thick and the aggravating internal cavities defects significantly reduced the joint strength. Correspondingly, the fracture mode of the friction stir lap welded 5052 alloy and DP590 steel was converted from the semi-brittle fracture into the full-brittle fracture. The maximum tensile shear force of 4.52 kN reached 75.2% of the Al 5052 base metal, obtained at the rotation speed of 750 rpm. However, from the combined perspective of integral bearing load capacity and local shear strength, the rotation speed of 500 rpm was recommended to achieve sound FSLW joints of Al5052/DP590.

Microstructure characteristics and mechanical properties of Al/Mg joints manufactured by magnetic pulse welding

The effective connection of 1050 Al and AZ31 Mg was realized by magnetic pulse welding. The maximum tensile-shear force of the dissimilar Al/Mg metal lap joint reached 97% of that of the 1050 Al alloy base material by optimizing the process parameters. The microstructure of dissimilar Al/Mg welded joints was analysed by Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS) and Electron Backscattered Diffraction (EBSD). The results show that the key to obtaining high shear strength of Al/Mg dissimilar metal joints is mainly due to the following two reasons. On the one hand, grain refinement and element interdiffusion occur at the interface. On the other hand, no intermetallic compounds are formed at the interface.

Effect of the laser texturing width on hot-pressing joining of AZ31B and CFRTP

Laser texturing was performed on the surface of AZ31B magnesium alloy to increase the bonding strength. Textured AZ31B and carbon fiber reinforced thermoplastics (CFRTP) were then joined by the hot-pressing joining process. The effect of various groove widths of laser textured grid on the AZ31B/CFRTP joint was investigated. The research results showed that the wettability of the molten CFRTP on laser textured AZ31B was increased by about nine times, and the contact angle was reduced from 104.0° to 48.8° with a groove width of 0.3 mm. The macroscopic morphology and interface of joints had no defects, when the groove widths were 0.2 mm and 0.3 mm. The tensile-shear test was carried out, and the maximum tensile-shear force of the joint was 2698.8 N in the case of 0.3-mm groove width, which was 2.1 times as much as that of the untreated joint. The maximum tensile-shear force was 65.43% of the CFRTP itself. A diffusion layer of 9 μm– 24 μm thick formed at the AZ31B/CFRTP joint. MgCO3 was identified at the joining interface. The mechanical interlocking and chemical bonding formed at the interface effectively improved the strength of the joint.

Research on the Influence of the AW 5754 Aluminum Alloy State Condition and Sheet Arrangements with AW 6082 Aluminum Alloy on the Forming Process and Strength of the ClinchRivet Joints.

Clinching joints with an additional deformable rivet are modifications of the clinching joints. The clinch riveting (CR) joint is formed indirectly by a deformable rivet. The research included an analysis of CR joints’ forming process for aluminum alloy sheets made of AW 6082 in T6 state condition and AW 5754 in three different state conditions: H11, H22 and H24. As a result of forming the joint for various sheet arrangements, the highest value of blocking the upper sheet in the lower sheet (tu) was obtained for the arrangements with two 5754-H24 aluminum alloy sheets. For such a large interlock parameter tu, the greatest thinning of lower sheet (tn) was obtained, which influenced the maximum tensile shear force and the joint failure mechanism. Based on the load-displacement diagrams obtained from the static shear test of lap joints, the total energy of failure and energy to achieve the maximum load capacity were calculated. The highest energy absorption to achieve the maximum load capacity, in the case of the same sheet materials, was obtained for the 5754-H11 aluminum alloy sheets. On the other hand, among the tested combinations, the highest value of energy absorption (for the joint maximum load capacity) was obtained for the sheet arrangement: top sheet AW 6082-T6 and the bottom AW 5754-H24. The highest value of the total energy up to fracture was obtained when the material of the top sheet was AW 6082-T6, and the bottom AW 5754-H22. For each sheet arrangement, a similar analysis of the joint strength parameters, interlock parameters and forming force were made.

Experimental Study on Joining by Forming of HCT590X + Z and EN-AW 6014 Sheets Using Cold Extruded Pin Structures

Due to stricter emission targets in the mobility sector and the resulting trend towards lightweight construction in order to reduce weight and consequently emissions, multi-material systems that allow a material to be placed in the right quantity and in the right place are becoming increasingly important. One major challenge that is holding back the rapid and widespread use of multi-material systems is the lack of adequate joining processes that are suitable for joining dissimilar materials. Joining processes without auxiliary elements have the advantage of a reduced assembly effort and no additional added weight. Conventional joining processes without auxiliary elements, such as welding, clinching, or the use of adhesives, reach their limits due to different mechanical properties and chemical incompatibilities. A process with potential in the field of joining dissimilar materials is joining without an auxiliary element using pin structures. However, current pin manufacturing processes are mostly time-consuming or can only be integrated barely into existing industrial manufacturing processes due to their specific properties. For this reason, the present work investigates the production of single- and multi-pin structures from high-strength dual-phase steel HCT590X + Z (DP600, t0 = 1.5 mm) by cold extrusion directly out of the sheet metal. These structures are subsequently joined with an aluminium sheet (EN AW-6014-T4, t0 = 1.5 mm) by direct pin pressing. For a quantitative evaluation of the joint quality, tensile shear tests are carried out and the influence of different pin heights, pin number, and pin arrangements, as well as different joining strategies on the joint strength is experimentally evaluated. It is proven that a single pin structure with a diameter of 1.5 mm and an average height of 1.86 mm achieves a maximum tensile shear force of 1025 N. The results reveal that the formation of a form-fit during direct pin pressing is essential for the joint strength. By increasing the number of pins, a linear increase in force could be demonstrated, which is independent of the arrangement of the pin structures.

Effect of laser cleaning on mechanical properties of laser lap welded joint of SUS310S stainless steel and 6061 aluminum alloy

Laser cleaning was successfully applied to laser lap welding of SUS310S stainless steel and 6061 aluminum alloy. The length and width of the fish scale pit tended to increase and decrease with increasing the scanning speed from 3000 mm/s to 7000 mm/s after laser cleaning. While, the depth of the fish scale pit was higher at the scanning speed of 5000 mm/s than the other. In the welded joint, except for metallurgical bonding, a relatively strong mechanical bonding occurred in the interface for the specimens cleaned at the scanning speeds of 3000 mm/s and 5000 mm/s during laser cleaning. The fish scale pit on the cleaned surface of stainless steel could improve the spread out of the melting aluminum alloy, causing the appearance of the relatively strong mechanical bonding. The maximum tensile shear force achieved 1948 N and increased 54% compared to the one without laser cleaning. The application of laser cleaning with the suitable parameters can effectively enhance the mechanical properties of the laser lap welded joints.

Effect of welding parameters on the microstructures and mechanical properties of double-pass aluminum/magnesium dissimilar metal friction stir lap welding joint

Different welding parameters (rotation speed, traverse speed, and overlap ratio) were used to perform friction stir lap welding (FSLW) on 1060 aluminum/AZ31B magnesium dissimilar metals. A response surface model was established in order to optimize the welding parameters. Compared with results at other traverse speeds, the joint exhibited a high welding efficiency and a tensile shear force at a welding speed of ν = 70 mm/min. When the same length is welded, the time required for welding speed 70 mm/min is 43 % of welding speed 30 mm/min and 71 % of welding speed 50 mm/min, respectively. Subsequently, through optical microscopy (OM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM), the effect of the overlap ratio (OR) on the macro and microstructure, mechanical properties of the joint were examined. A good metallurgical bond and mechanical interlocking combination were formed at the interface. As the OR was increased, the fluidity of the material was further improved, and the content of intermetallic compounds (IMCs) also increased sharply. The micro-hardness test results showed that the weld-nugget area exhibited a higher hardness due to the formation of IMCs. When ν = 70 mm/min and ω = 1500 rpm, an increase in the OR from 50 % to 75 % caused the maximum tensile shear force of the joint to decrease sharply, and three fracture modes of the joint fractures were identified.

Self‐Piercing Riveting of Hot Stamped Steel and Aluminum Alloy Sheets Base on Local Softening Zone

Self‐piercing riveting (SPR) has been used to joint steel to aluminum alloy sheets in multimaterial car body. It is a challenge to joint high strength steel to aluminum alloy by SPR process, especially for materials with high strength and large thickness. Herein, the SPR process for 1500 MPa hot stamped steel and aluminum alloy sheets is studied by experiment and simulation method. The laser heat treatment process is applied to the hot stamped steel sheet before joining. The relationship between heat treatment process and hardness distribution is studied and the softening zone with hardness less than 300 HV is obtained. Furthermore, the local softening zone is joined to an aluminum alloy sheet by SPR process. In the process, the rivets with high hardness are used to pierce the steel sheet. The failure mode and maximum tensile shear force of the joint are studied. At the same time, the joints without laser heat treatment are compared. The results show that the interlock and the maximum shear force for laser heat treatment increase by 91% and 26%, respectively.

Influence of processing window on laser welding-brazing of Al to press-hardened 22MnB5 steel

Laser welding-brazing of AA6061 alloys and press-hardened 22MnB5 steel in lap configuration was carried out with Zn-Al15 filler metal. The processing window in different defocused distances was investigated and its influence on microstructure and mechanical properties of Al/steel dissimilar joints was explored. The results revealed that good appearances could be acquired in different processing windows with variation of defocused distances. The processing window was enlarged with increase of laser spot diameters, from laser power of 2.1–2.3 kW in defocused distance of +20 mm (laser spot diameter of 1.4 mm) to 2.8–3.6 kW in defocused distance of +40 mm (laser spot diameter of 2.4 mm). The thickness of interfacial intermetallic layer increased gradually from 0.47 to 1.86 μm for defocused distance of +20 mm to 3.76–11.03 μm of +40 mm. The newly formed phase at the interface at defocused distance of +20 mm was identified as Fe2(Al, Zn)5 and those were identified as the mixture of Fe2(Al, Zn)5 and FeZn10 when the defocused distances were +30 mm and +40 mm. The tensile-shear test of laser welded-brazed joints produced in various processing windows showed two types of fracture modes occurred. The interfacial failure appeared with the defocused distance less than +30 mm. The maximum fracture load reached 2793 N, representing 84.6% joint efficiency in regard to aluminum alloys. However, when the defocused distance increased to +40 mm, the maximum tensile-shear force decreased to 2242 N and failure occurred in the softening region of HAZ in aluminum alloy caused by effect of large laser irradiation. At larger defocused distance, the weak position of the dissimilar joints would transfer from the interface to the HAZ of the aluminum alloy, resulting in a bottleneck to improve mechanical property of joints.

Process parameter optimisation in pinless friction stir spot welding of dissimilar aluminium alloys using Multi-start algorithm

Friction stir spot welding, a solid-state metal joining process has been utilised to join dissimilar aluminium alloys using pinless tools. The optimal welding conditions were predicted using the Multi-start algorithm with 25 starting points and were validated by confirmation tests. The Multi-start algorithm predicted the maximum tensile shear force of 6.28 kN at the tool rotational speed of 841.83 r/min, plunge depth of 0.618 mm, shoulder diameter of 24.99 mm, plunging speed of 0.04 mm/s and dwell time of 8 s. The scanning electron microscopy analysis revealed the formation of flatter hooks in the weld zone. The electron backscatter diffraction scans revealed a decrease in grain size at the lower sheet (Al 5754) due to the action of 30 kN axial force during pinless friction stir spot welding. Two different modes of fracture were observed: (i) nugget pull-out with necking; (ii) shearing. The fracture modes were observed to be dependent on the process parameters like shoulder diameter and plunge depth.

Effect of welding parameters on weld formation quality and tensile-shear property of laser welded SUS301L stainless steel lap filet weld

Laser welding of lap-filet joints SUS301L austenitic stainless steel plates were carried out with filler wire. Results showed that the weld zone was composed of columnar austenite and a small amount of δ-ferrite. The effect of feed direction, wire distance (H), laser incident position (L) and laser incident angle on the wire melting mechanism, weld pool geometry, metal transfer modes and heat distribution were studied with the assistance of the high speed camera recording the welding process. Better weld quality was obtained under the circumstances of leading direction, wire distance 0.5mm, laser incident position 0.5mm, and laser incident angle 0̊. The fracture was always located in the weld where the thickness of it was the smallest. There was a linear relationship between the weld width and the smallest weld thickness. The maximum tensile-shear force was 24.46kN. The fracture mode was ductile fracture with fracture surface dimples.

Effect of scanning speed on laser joining of carbon fiber reinforced PEEK to titanium alloy

Laser lap joining of carbon fiber reinforced plastics (CFRP) to titanium (Ti) alloy using various scanning speed was performed and the influence of scanning speed on joining process was investigated. The high speed camera was adopted to visualize the joining process and defects. The tensile-shear force was tested and the fracture surface was observed by optical microscope. Besides, the numerical simulation of temperature field was conducted to reveal the joining mechanism. The results indicated that fewer defects on titanium alloy surface and less bubbles inside CFRP were obtained with the experimental condition of higher scanning speed. Both mechanical interlocking and chemical bonding occurred at the interface. The compound layer was generated and was confirmed as CTi0.42V1.58 phase because of the carburization of titanium alloy. The thickness of compound layer increased with the decrease of scanning speed. Tensile-shear force first increased and then decreased as the travelling speed increased. When the travelling speed was 0.8 m/min, maximum tensile-shear force of 1024 N was obtained. The bonding width of the resin, and bonding ratio of the mixture of carbon fibers and resin also reached the maximum value at this experimental condition. This behavior was verified by results of temperature field simulation that the melting temperature range of CFRP first increased and then declined as the scanning speed increased. The fluctuation of the tensile-shear force of the CFRP/Ti joint was also explained by the developed simulation model.

Achieving strong friction lap joints of carbon-fiber reinforced plastic and metals by modifying metal surface structure via laser-processing pretreatment

Strong dissimilar joints of metals and carbon fiber reinforced plastic (CFRP) are highly demanded for the lightweight design in many fields, which, however, are rather challenging to achieve directly via welding. In this study, 5052 Al alloy and plain carbon steel were first pretreated by a laser-processing method to create rather coarse porous metal surfaces, which were then welded to polyamide 6 based CFRP using friction lap joining. The maximum tensile shear force of the dissimilar joints of CFRP-Al alloy and CFRP-steel achieved 4.9 kN, and 3.9 kN, respectively, and the joint efficiency achieved 78% and 62%, respectively, which were more than three times as those of the CFRP- as-received metal joints. This is the first report on the strengthening of the metal-CFRP friction based joints via the assisting laser treatment technique. The significant improvement of the joint strength could be attributed to a great increase of the mechanical anchors and the chemical bonding area at the metal-CFRP interface.

Laser conduction welding characteristics of dissimilar metals Mg/Ti with Al interlayer

The immiscible and nonreactive characteristics of Mg/Ti dissimilar metals restrict the metallurgical bonding and reliable joining of them. To solve this problem, the Al interlayer between Mg/Ti was added. The Mg/Ti joint without addition of Al interlayer could not be welded, while relatively acceptable appearance was obtained when adding Al interlayer. The interfacial reaction was improved with the assistance of Al interlayer resulting in metallurgical bonding at the interface. The TiAl3 phase formed at the direct laser irradiation zone. Note that the interfacial reaction layer increased little with the increasing thickness of Al interlayer. The interfacial reaction layer was mainly restricted by dissolution of Ti element. Temperature field and thermodynamic calculation assisted to prove the interfacial reaction at the fusion zone/Ti interface and the formation of TiAl3. The tensile-shear testing indicated that the maximum tensile-shear force could reach 2230 N/cm (about 81% of that of AZ31B Mg alloy base metal) when the laser power was 2300 W and the thickness of added Al interlayer was 0.05 mm. The tensile-shear force decreased when network structure of Mg17Al12 precipitated in the weld zone. The fracture path changed from fusion zone/Ti to Mg fusion line when the thickness of Al interlayer exceeded 0.12 mm.

Direct joining of oxygen-free copper and carbon-fiber-reinforced plastic by friction lap joining

Oxygen-free copper (Cu) was successfully joined to carbon-fiber-reinforced thermoplastic (CFRTP, polyamide 6 with 20wt% carbon fiber addition) by friction lap joining (FLJ) at joining speeds of 200–1600mm/min with a constant rotation rate of 1500rpm and a nominal plunge depth of 0.9mm. It is the first time to report the joining of CFRTP to Cu by FLJ. As the joining speed increased, the tensile shear force (TSF) of joints increased first, and decreased thereafter. The maximum TSF could reach 2.3kN (15mm in width). Hydrogen bonding formed between the amide group of CFRTP and the thin Cu2O layer on the Cu surface, which mainly contributed to the joint bonding. The influence factors of the TSF of the joints at different joining speeds were discussed. The TSF was mainly affected by the joining area, the degradation of the plastic matrix and the number and the size of bubbles. As the joining speed increased, the influence factors varied as follows: the joining area increased first and then decreased; the degradation of the plastic matrix and the number and the size of bubbles decreased. The maximum TSF was the comprehensive result of the relatively large joining area, small degradation of the plastic matrix and small number and sizes of bubbles.