Maximum Tensile Shear Strength Research Articles

Research on the Optimization of Oscillation for the Joint Quality of Laser Welded Joints in Automobile Seat Frames

The increasing adoption of high-strength steel in automotive manufacturing has made laser welding a preferred technique due to its ability to reduce thermal deformation and facilitate single-sided welding. Despite these advantages, challenges persist, particularly in achieving precise welds at the edges of seat frame assemblies. This study explores the application of laser weaving techniques to improve joint strength and penetration depth. The critical variables evaluated include defocusing distance and weaving parameters, which were assessed for their impact on penetration depth, effective joint width, and edge weld quality in a three-sheet stack of dual-phase (DP) steel. Results indicate that increasing the defocusing distance from 5 mm to 20 mm at a fixed oscillation frequency of 20 Hz leads to a corresponding increase in surface bead width. A significant correlation was found between the effective joint width and maximum tensile shear strength, with the highest strength of 34.6 kN observed at an 8 mm defocusing distance. Additionally, the use of oscillation in the welding process improved tensile shear strength by approximately 9 kN compared to line welding without oscillation. Oscillation also enhanced microstructural properties, demonstrating that optimal welding conditions can be achieved even with off-position welding. These improvements are attributed to minimized heat-affected zone (HAZ) effects, which contributed to increased joint strength and hardness.

Dissimilar joining of aluminum alloy and low-alloy carbon steel by resistance spot welding

In this work, the resistance spot welding (RSW) process was performed to join aluminum alloy and low-alloy carbon steel plates. The macro characteristics including nugget diameters and indentation rates, microstructure and tensile-shear strength of RSW joints were investigated. The results showed that the nugget of the RSW joints comprises a ‘bowl’ shape nugget on the aluminum side and an elliptical shape nugget on the steel side. Also, the intermetallic compound (IMC) layers containing Fe4Al13 and Fe2Al5 were formed around the aluminum/steel interface with the steel side having a tongue-shape and the aluminum side having a needle-shape. According to metallurgical evaluation and temperature distribution of RSW joints analyzed by the finite element method, the nugget on the aluminum side contained the dendritic grains and equiaxed dendritic grains. The nugget on the steel side consisted of a large amount of bainite and a small amount of coarse lath martensite. The nugget diameters and the indentations rates of RSW joints increased when increasing either welding current or welding time, and decreased when increasing the electrode pressure. The maximum values of nugget diameter and indentation rate of RSW joints were 9.076 mm and 4.144% when using the welding current of 16 kA, welding time of 450 ms and electrode force of 3 kN. In tensile-shear tests, the RSW joints showed a shear-off fracture mode. When increasing the welding current, welding time or electrode force, the tensile-shear strength of RSW joints increased first, and then reached a maximum, and finally decreased. The welding current of 16 kA, the welding time of 300 ms, and the electrode pressure of 3 kN were considered as the optimal welding parameters in the present study which resulted in the maximum tensile-shear strength of 2.24 kN. In addition, the IMC layers of the RSW joints exhibited a uniform and continuous appearance with a thickness of approximately 1.9 μm, and the IMC layer in the central area was thicker than that in the edge area.

An investigation on tensile shear strength of CMT spot weld-brazing of 5052 aluminium alloy and SS 400 galvanized steel

The main purpose of the research is to investigate the effects of spot weld-brazing variables, such as cold metal transfer (CMT) modes and current, on the tensile shear strength of 5052 aluminium alloy for dissimilar joining to SS400 galvanized steel.The method employed in the study was a 3k full factorial design with three replications. Analysis of variance (ANOVA) techniques were employed to identify the variables that influenced the responses of interest. The response optimiser method displayed which factors affected the variables and their impact on strength. In addition, the response optimiser method was employed to find which factors produced the best value for the response variable. A mathematical model was developed to predict the strength of the joints. An optical microscope (OM) and scanning electron microscope (SEM) were also employed to confirm the microstructure. Energy dispersive spectroscopy (EDS) was used to determine the chemical composition of the microstructure.The strength of the weld-brazing joints was affected by the modes and currents used in the joining process. The weld-brazing mode selection was found to have an impact on strength. The synergic mode was shown to have a strength greater than the CMT pulse and pulse synergic modes. The excess or little weld-brazing current was shown to be unsuitable for the joint. The maximum tensile shear strength value was obtained in the synergic mode with a current of 110 A. The resulting prediction model was evaluated with the newly collected experimental data, and the average per cent error was estimated to be 2.07%. In addition, the reaction layer at the aluminium alloy and steel interface was composed of a Fe(Al, Si)3 phase. The optimal conditions for the spot weld-brazing activities resulted in a larger fracture area, a small contact angle, and excellent weld bead geometry.The prediction accuracy of the model appeared satisfactory. However, the altered chemical composition of the filler metals and substrate materials could impact the findings. It is recommended that the electrical signal waveform be studied during spot weld-brazing, as well as the characteristics of other material joints with various other parameters.The weld-brazing mode and current had no significant effect on the type of interface layer of the joints.It is highly possible that the CMT spot weld-brazing technique could be applied to join other dissimilar materials in order to reduce the joining time, but the filler metal chosen must be appropriate.

Structure and properties of the hot pressing molded anodized aluminum alloy/polyformaldehyde hybrids

The metal-plastic hybrid is one of the important solutions for lightweight and high-strength composite. The anodized aluminum alloy（AAA）/polyformaldehyde（POM） hybrids with excellent mechanical properties were processed by the hot pressing technology. The surface of the aluminum alloy plate was firstly pretreated with phosphoric acid and oxalic acid anodizing, resulting in a large number of micro-nano scale pores on the surface. These pores were well embedded with plastic melt during hot pressing to form micro-nano mechanical interlocking structures and the Al–O–C chemical bond at the interface is generated, thus ensuring good bonding strength at the metal and plastic interface. The maximum tensile-shear strength of the metal-plastic hybrid was 30.65 MPa, meanwhile, the metal-plastic interface failure presented mainly a mixed failure mode, including resin removal from the metal surface and plastic tearing from the plastic surface. At the same time, the salt spray test, thermal shock test, and variable temperature test were adopted to investigate the application performance of the metal-plastic hybrid. The Al/POM hybrids were able to maintain their mechanical strength above 20 MPa for 28 days in a salt spray environment, 14 times in a thermal shock cycle, and at high temperatures. The high mechanical strength of hybrid has good potential for automotive applications.

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 %.

Improving interface bonding strength of laser-welded steel/CFRTP hybrid joint via bilayer silane film

The γ-aminopropyltrimethoxysilane (γ-APS) and γ-(2,3-epoxypropoxy) propyltrimethoxysilane (γ-GPS) single or bilayer silane film was produced to improve the tensile property of laser-welded 304 stainless steel/CFRTP joint in this work. The bonding mechanism at joint interface was investigated through experiments as well as density functional theory (DFT) calculation. Si-O-Fe covalent bonds were formed between steel and different silane films. Hydrogen bonds were induced at the interfaces of silane coating/polymer sides. The binding energy calculation results suggested that the binding between γ-APS silane coupling agent and steel was more stable than that of γ-GPS and steel. The binding energy of −3.37 eV between amino group in γ-APS and carbonyl group in CFRTP was greater than the binding energy of −4.84 eV between epoxy group in γ-GPS and amide group in CFRTP, which indicated stronger interaction was obtained between γ-GPS and polymer compared to the interaction between γ-APS and polymer. The bilayer silane coating could combine the dominant functional groups of silane monolayer film to obtain stable bonding on both metal side and CFRTP side. Moreover, compared with silane single film, longer silane oligomer molecular chain length was provided by bilayer silane film, resulting in more entanglement sites between silane film and CFRTP and the increased joint mechanical property. The steel/CFRTP hybrid joint reached maximum tensile shear strength of 17.2 MPa, which was further increased by 115.0% and 79.2% than that obtained by γ-APS and γ-GPS silane single coating, respectively.

The effect of groove texturing direction on laser joining of titanium alloy to CFRTP

Hybrid structure of titanium alloy and carbon fiber reinforced thermoplastic composite (CFRTP) provided a new direction for lightweight and laser had a great prospect for application in joining metal/plastic. In this work, before laser joining TC4 (Ti6Al4V) and CFRTP (PA66), three groove micro-structures in different texturing direction (0°, 45°, 90°) were prepared on the TC4 surface respectively by nanosecond laser. The effect of different groove texturing was studied. Research results showed that the existence of three groove texturing increased the affinity between TC4 and molten CFRTP to the same extent. The resin-carbon fiber mixture adhered to the surface of TC4 after laser texturing increased obviously. However, the groove micro-structure had different impact on the tensile performance of the joint. The maximum tensile shear strength could reach 10.9 MPa, which was increased by 111 % compared with the untreated when the groove micro-texturing direction was perpendicular to the tensile direction (0° texturing) while the 90° textured joint performance was only increased by 42.9 %. The FEA results revealed that micro-texturing provided mechanical resistance for the joint during the tensile process and 0° micro-texturing provided the largest mechanical resistance followed by 45° and 90° micro-texturing.

Dissimilar joining of TC4 and SiCp/6092Al matrix composite by laser lap welding technology

This investigation examined the feasibility of laser welding of TC4 titanium alloy (TC4) and SiCp/6092Al matrix composites (AMC) with different lap structures. The welding formation, microstructure, mechanical properties, and intermetallic compounds (IMCs) for the two different laser lap joints were analyzed. The results showed that a Y-shape welded joint was obtained for TC4/AMC lap structure and an X-shape joint was formed for AMC/TC4 lap structure at the same welding parameters. The intermetallic compounds generated in lap joints between TC4 and AMC were mainly composed of TiAl3, Al4C3, TiAl, and TiC. The amount of porosity and cracks in the TC4/AMC joints was less than that in the AMC/TC4 welded joints. The maximum tensile shear strength of 210.3 N/mm was achieved for the TC4/AMC lap joints, which was 46.2% higher than that of the AMC/TC4 joint.

Influence of welding environment on joint characteristics of friction stir lap welded AA7475-PPS polymer hybrid joints

This study explores the impact of air and underwater welding environments during friction stir lap welding (FSLW) of AA7475 and Polyphenylene-sulfide (PPS) polymer dissimilar materials. Response surface methodology-based desirability function approach was used to identify the optimal FSLW process parameter set in an underwater environment. The joint characteristics, such as microstructure, mechanical properties of the joints, and physicochemical changes in the polymer with the air and underwater FSLW, were compared. The maximum tensile lap shear strength was attained as 12 MPa and 19 MPa in the air and underwater weld environment, respectively. Microstructural examination revealed that the bonding mechanism in FSLWed hybrid joint in both weld environment conditions is macro/micromechanical interlocking. Based on the findings of a Differential Scanning Calorimetry study, the FSLW technique causes the loss of crystallinity in the polymer. The study found that the welding environment significantly impacted air voids formation, tensile characteristics, and loss of crystallinity in polymers.

Effect of Flame Treatment on Bonding Performance of GF/EP Pultrusion Sheets Used for VARI Process

This paper presents an easy and low-cost flame treatment method to improve the bonding performance of GF/EP (Glass Fiber-Reinforced Epoxy) pultrusion plates, which are using widely for large size wind blades. In order to explore the effect of flame treatment on the bonding performance of the precast GF/EP pultruded sheet vs. the infusion plate, the GF/EP pultruded sheets were treated with different flame treatment cycles and were embedded in the fiber fabrics during the vacuum-assisted resin infusion process (VARI). The bonding shear strengths were measured by tensile shear tests. It is found that after 1, 3, 5, and 7 flame treatments, the tensile shear strength between the GF/EP pultrusion plate and infusion plate increased by 8.0%, 13.3%, 22.44%, and -2.1%, respectively. This indicates that the maximum tensile shear strength can be obtained after five times of flame treatment. In addition, DCB and ENF tests were also adopted to characterize the fracture toughness of the bonding interface with the optimal flame treatment. It is found that the optimal treatment gives increments of 21.84% and 78.36% for G I C and G II C, respectively. Finally, the surficial topography of the flame-treated GF/EP pultruded sheets were characterized by optical microscopy, SEM, contact angle test, FTIR, and XPS. The results show that flame treatment plays an impact on the interfacial performance through the combination of physical meshing locking and chemical bonding mechanism. Proper flame treatment would remove the weak boundary layer and mold release agent on the surface of the GF/EP pultruded sheet, etch the bonding surface and improve the oxygen-containing polar groups, such as C-O and O-C=O, to improve the surface roughness and surface tension coefficient of pultruded sheet to enhance the bonding performance. Excessive flame treatment destroys the integrity of epoxy matrix on bonding surface which results into the exposure of the glass fiber, and the carbonization of release agent and resin on the surface loosen the surficial structure, which reduces the bonding properties.

Structure–Property Relationship in High-Strength Aluminum Alloys/Stainless Steel Brazed Joints

In many industrial sectors, for example, aerospace, automotive and high-performance electronic industries, there is a significant need to join dissimilar materials. In the case of medium-strength aluminum alloys, joints are commonly manufactured using Al-Si brazing fillers with a melting temperature of 575 °C. In comparison to medium-strength aluminum alloys, high-strength aluminum alloys exhibit lower melting temperatures. Therefore, the joining possibilities are limited. Due to the lower melting temperature of about 500 °C, Al-Ag-Cu brazing fillers allow the joining of these alloys. In this study, high-strength aluminum alloys/stainless steel joints were produced via induction brazing and vacuum furnace brazing. The mechanical properties of the joints were determined using tensile shear tests as well as fatigue tests at ambient temperature. The joints produced via induction brazing at 520 °C without holding time reached a maximum tensile shear strength of 32 MPa. The joints failed in the braze metal close to the reaction zone. The joints brazed in the vacuum furnace at 540 °C for 10 min reached a maximum tensile shear strength of 18 MPa. The fractures occurred in the reaction zone, especially inside the Al7Fe2Si intermetallic layer. The thickness of the intermetallic layers as well as the reaction zone had a significant influence on the joining strength and the fracture mechanism of the brazed joints. The results of the fatigue tests showed that the joints brazed without holding time achieved the defined limited number of cycles of 1 × 107 at a stress amplitude of 4 MPa. For all the fatigue-tested samples, the fracture occurred in the braze metal, especially in the eutectic. Hence, the reaction zone does not significantly influence the fracture mechanism of high-strength aluminum alloy/stainless steel brazed joints during cyclic loading.

Experimental study on properties and structure of magnesium alloy/PC/ABS hybrid materials prepared by hot-press molding technology

Magnesium alloy/PC/ABS composites were prepared by hot-press molding technology. The bonding strength is the crucial factor to influence the comprehensive performance of this composite, and it was closely related to the different processing parameters such as temperature, pressure and time. After exploring their relationship, the optimal hot-press processing condition was obtained. The micro- and nano-structure of composites also received attention. Before hot-pressed, the magnesium alloy surface was treated by micro-arc oxidation in order to construct the nano-sized pores. With the aid of scanning electron microscope (SEM) and atomic force microscope (AFM), a refined mechanical interlocking structure was observed with the formation of coordinate bonds at the interface of an alloy-polymer hybrid. The binding energy of the chemical elements at the bonding interface of the composite was also tested by X-ray photoelectron spectroscopy (XPS) and the analysis concluded that coordination bonds were formed at the bonding interface. The maximum tensile shear strength of the composite reached 9.48 MPa.

Strengthening the bonding interfaces of hybrid titanium carbon laminates by bionic micro texture and carbon nanotube pinning

A reliable strategy to enhance the bonding ability in hybrid titanium carbon laminates (HTCLs) is proposed, which is based on the pinning effect produced by bionic micro texture etched by laser on titanium and multi-walled carbon nanotubes (MWCNTs) introduced into adhesive layer. The characteristic of bionic micro texture is determined, and the strengthening mechanism of bonding interfaces is revealed. The HTCLs samples with various micro texture groove widths, laser scanning times and MWCNTs content are fabricated via an autoclave process. The micro texture morphologies, surface wettability, interlayer bonding properties under different conditions are studied. Results show that the recast layers formed on titanium during etching are beneficial to improve the interfacial bonding properties. Compared with no micro texture, the contact angle with micro texture can be reduced by 68.4%. Both micro texture and MWCNTs can reduce the defects at the interlayer interfaces and improve the interfacial adhesion. In this work, the maximum tensile shear strength (TSS) and interlaminar shear strength (ILSS) can be obtained with the micro texture groove width of 30 μm, the laser scanning of 30 times and the MWCNTs content of 0.4 wt%, which are 56.39% and 32.84% higher than that without any treatment, respectively.

Microstructure and mechanical properties of friction stir lap welds between FeCoCrNiMn high entropy alloy and 6061 Al alloy

To investigate the microstructure and mechanical properties of the dissimilar joint between high entropy alloys (HEAs) and Al alloy, FeCoCrNiMn was joined to 6061 Al alloy by friction stir lap welding (FSLW) at tool rotation speeds from 900 rpm to 1800 rpm. Systematic tilting high-resolution transmission electron microscopy patterns were applied to study the interfacial microstructure. A nanoscale (< 250 nm) interfacial layer was found at the 6061/FeCoCrNiMn interface and the phase formed in this layer was identified as Al13Fe4-type intermetallic compound (IMC) with the Fe-sites occupied by HEA elements. Microsegregation of HEA elements was observed in this Al13Fe4-type IMC in two different modes: 1) co-segregation of Cr and Mn and co-depletion of Co and Ni, for the majority of the interfacial layer, and 2) co-segregation of Co and Ni and co-depletion of Cr and Mn, mainly in regions adjacent to the Al alloy side and sporadic in the middle. The maximum tensile lap shear strength reached 151 MPa, which was approximately 73 % of the shear strength of 6061 base material. The joint fracture occurred within Al alloy nearby the interface rather than right along the interfacial layer, suggesting high interfacial metallurgical bonding achieved in this study.

Analysis and prediction of the joint strength of friction stir welded Aluminium 5754 to polyamide using response surface methodology and artificial neural network

Lightweight hybrid structures are developing these days due to increased demand for fuel economy and lower emissions in the automotive and aerospace industries. This study aims to analyse and optimise the influence of friction stir welding (FSW) process parameters on the tensile shear strength of the aluminium-polyamide hybrid joint. The study on the influence of each parameter on the joint strength helps define the bonding mechanism while joining aluminium-polymer hybrid structures. Optical microscopy and scanning electron microscopy (SEM) were used for microstructural examination. A SEM image of the weld’s cross-sectional area shows micro and macro mechanical interlocks with a small interfacial gap which indicates better joint strength. An elemental area mapping investigation of the weld zone reveals fine polymer and aluminium mixing along the interaction region. In addition, FSW parameters have been optimized to maximize the tensile shear strength of aluminium-polyamide hybrid joints. A mathematical model for tensile shear strength in terms of FSW parameters is developed using response surface methodology (RSM). A predictive model was developed using an Artificial Neural Network (ANN) to validate RSM predicted results. The analysis of variance (ANOVA) shows that the actual and predicted values have a satisfactory correlation. ANN methods are better than regression models in predicting tensile shear strength within input welding parameter ranges. The process variables were optimised using the desirability function analysis. The maximum joint tensile shear strength of about 19.74 MPa and attained at optimal FSW parameters, i.e. rotational tool speed of 1421 r/min, welding speed of 27 mm/min, and tool tilt angle of 1°. The regression coefficient for the ANN model was 0.988 for the test data set, indicating that the developed model is appropriate for predicting tensile shear strength.

Enhancing interfacial bonding in friction stir lap welding of light metal and carbon fiber reinforced polymer composite

The key strategic technology of automotive lightweight design advances the development of light metal/carbon fiber reinforced polymer composite hybrid joining. In this work, Al alloy (AA6061) and carbon fiber reinforced polyamide 66 (CF-PA66) were joined using friction stir lap welding (FSLW) technique with laser ablation pretreatment. The enhancing interfacial bonding mechanism and failure analysis of hybrid joints were investigated in detail. The maximum tensile-shear strength reached 24.48 MPa based on the bonding mechanism including macro/micro/nano-mechanical interlocking and chemical bonding, increasing by approximately 600 % compared with FSLW joints without surface pretreatment. Fracture located at weak interfaces between metal and composite without laser-textures and mixing region of resin and carbon fibers. This study provides novel insights into material-process-structure integrated lightweight design and benefits future research in the processes to enhance metal/composite hybrid structures.

Interface Characteristics and Mechanical Properties of 2024 Aluminum Alloy and 304 Stainless Steel Dissimilar Alloys FSLW Joint with Ni Interlayer

The composite structure of aluminum and steel (Al/steel) dissimilar metals has been applied in manufacturing industries for lightweight products, and friction stir lap welding (FSLW) has advantages for the welding of these two metals. To further enhance the strength of the Al/steel FSLW joint, a 0.02 mm thick nickel (Ni) foil was chosen as the interlayer, and slight plunging depth of a tool pin into the lower steel sheet was designed, which can respectively change the intermetallic compounds (IMCs) type and produce small welding heat. Choosing dissimilar 2024 aluminum alloy and 304 stainless steel materials as the research subject, the characteristics of the lap interface and the mechanical properties of the joint were mainly discussed. The results showed that the lap interface between the upper aluminum and lower steel sheets was made up of an AlNi3 IMCs layer, hook structure and mechanical occlusion. The AlNi3 IMCs layer with 2 μm thickness was in a reasonable range positive to the joint strength. When the rotating speed of the stirring tool increased from 800 to 1200 rpm and the welding speed of 75 mm/min was constant, the hook structure and the mechanical occlusion were both enhanced, and the tensile shear strength of the joint was decreased. A maximum joint tensile shear strength of 217 MPa was obtained at 800 rpm, and the strength value was 47.2 percent of that of the 2024 aluminum alloy base material. The Al/steel joint with shear fracture mode presented a brittle–ductile mixed fracture.

Dissimilar laser lap welding of Mg and Al alloys using a CoCrFeNi medium-entropy alloy interlayer

Laser welding of Mg to Al dissimilar metals is of great significance in various industries, such as automobile, electrical, electronics, and energy systems, which promotes lightweight composite structure. However, Mg-Al intermetallic compounds (IMCs) have tremendous detrimental effects on the dissimilar metal joining of Mg to Al. In this work, dissimilar Mg/Al alloys joints with CoCrFeNi medium-entropy alloy (MEA) powders interlayer were achieved by the laser welding process, and the effect of different laser powers on the microstructure and mechanical properties of the joints was analyzed, reaching a maximum tensile shear strength of 100.12 MPa. The formation mechanism of the interface was investigated by experimental investigations and thermodynamic calculations. In addition, a numerical simulation of the laser welding process was carried out to reveal the temperature field of the molten pool and the flow change process. Based on the law of multi-component HEA phase formation, the interfacial metallurgical products were calculated and analyzed. The results of the energy dispersive spectroscopy show that the molten CoCrFeNi MEA powders reacted with Al to form Al-rich AlxCoCrFeNi phase, due to a more negative generation enthalpy compared to Mg-Al IMCs. With the increase of laser power, the Al-rich AlxCoCrFeNi phase mixed layer went through four states of agglomeration, continuity, interruption and dispersion, while the IMCs at the interface gradually increased and finally tend to be continuity. Due to the physical barrier of MEA and formation of Al-rich AlxCoCrFeNi phase, the formation of the Mg-Al IMCs phase was effectively suppressed, which improved the shear properties of the joints. The material- microstructure-property relations was established in this work, which facilitated the development of laser welding technology for Mg and Al alloys.

탄소섬유 강화플라스틱의 레이저 표면처리 적용에 의한 이종 접합부의 접합강도 개선에 관한 연구

The adhesive bonding technology of carbon fiber reinforced plastics (CFRP) and aluminum alloys, is one of the lightweight joining technologies for automobiles. The strength and properties of the bonded joint, depend on the surface of the bonded part that the adhesive touches. Thus, proper surface treatment is one of the most important steps in the bonding process. The laser surface treatment of carbon fiber composites is a new form of green and environmental surface treatment technology, which can effectively clean coatings and pollutants on the surface of materials. It is also possible to improve the bonding shear strength, by changing the microstructure and roughness of the material surface through laser micro texture processing, to form a mechanically interlocked structure. In this study, a pulsed laser was used to treat the surface of CFRP. By changing the scanning line spacing during laser micro texturing, the effect of laser micro texturing on the surface morphology of CFRP and the strength of aluminum alloy bonded joints was investigated. Results show that in the laser micro texturing process, when the scanning line spacing was 0.3 mm, the maximum tensile shear strength was 14.5 MPa, approximately 200% higher than that without laser treatment.

Influence of cooling conditions on tensile lap shear strength and microstructure of friction stir welded aluminum alloy 5052-H32 and polycarbonate light weight hybrid joint

The joining of dissimilar materials, notably polymer and metal, is incredibly demanding due to the differences in the materials' mechanical, chemical, and thermal characteristics. In this present study, the feasibility analysis of dissimilar materials joints of aluminum alloy AA5052-H32 and polycarbonate (PC) was performed utilizing Friction Stir Welding (FSW) in the lap joint taper threaded tool pin profile. Response surface methodology (RSM) was implemented as a statistical design of the experiment tool for working process parameter optimization. Optical and Field emission scanning electron microscopy was employed to characterize the detailed microstructure of friction stir welded hybrid joint of AA5052-H32 alloy and PC. The mechanical and metallurgical findings demonstrate that AA5052-H32 and PC sheets were effectively bonded together utilizing a mix of macro mechanical interlocking and secondary chemical adhesive bonding of the materials, providing a viable relaxation to adhesive bonding or mechanical fastening. The hardness of the polymer in as-received conditions welded normally and in underwater conditions was measured onshore D hardness scale. The joint obtained at a rotational speed 1118 rpm and welding speed 48 mm/min with a 2° tilt angle had the maximum tensile lap shear strength of 14.86 MPa in air-cooled and 12.47 MPa in a water-cooled environment. Additionally, shore D hardness for optimal set of process parameters were 72 and 75 for air-cooled and water-cooled conditions respectively.