Joint Quality Research Articles

Joint Quality Assessment of Ultrasonic Metal Welded Parts by Fracture Surface Evaluation

In ultrasonic metal welding, low specific resistances and large joining surface cross-sections require the use of mechanical testing to quantify the joint quality. In this study, different quality features of ultrasonically welded joints made of pure copper sheet are investigated during the successive phases of joint formation. Two test series with different workpiece geometries are examined. It is shown that mechanical quality features such as shear and peel forces behave differently over the formation of the joint and are not transferable. As an alternative to these, laser scanning microscopy is used to record images of the fracture surface that describe the growth of the joint area during formation. The study finds that shear tensile force growth and joint area growth are non-linear and comparable, with optimized welds achieving joint areas of 30 mm2 out of 64 mm2 and 6 mm2 out of 16 mm2. Although overall quality increases with increasing welding time, the material strength in the joint zone decreases. Depending on the original rolling condition, between 43% and 59% of the original material strength can be identified as the joint strength. The automatic analysis of fracture images is a suitable alternative to mechanical testing for similar joints.

Industrial Radiography Testing & Technique Safety for Human Body

The use of Industrial Radiography for examining the quality of Weld joints is very popular worldwide. In India, many welding activities like construction and laying the huge pipelines for gas and water transportation and distribution as well construction of storage tanks are performed. The objects are working under high pressure and therefore, it is important to produce the weld beads with high quality. Industrial radiography uses ionizing radiation to view objects in a way that cannot be seen otherwise. The method has grown out of engineering, and is a major element of non-destructive testing (NDT) to inspect materials for hidden flaws. The radiation caused by these facilities is very dangerous however, with the use of new technologies and proper protection, risks of injury and death associated with radiation can be greatly reduced. Use or radiation sources are associated with a certain amount of radiation hazard. With proper card, this can be minimized. Radiation hazards may be broadly classified as external hazards an internal hazard. External hazards occur when the source of radiation is outside the body and internal hazards arise when the source for radiation gets into the human system. Hazard evaluation is necessary in order to adopt suitable measures to control radiation exposure. The problem of internal hazard does not arise in the use of X-ray equipment. It is considerably easy to estimate the external radiation hazard and there are a number of devices suitable for this purpose.

Forming quality and static properties of self-piercing riveted joints of hot-rolled steel and aluminum alloy sheets

The self-piercing riveting (SPR) Forming and tensile tests of hot-rolled steel sheet BR1200HS and aluminum alloy sheet AA 6082-T6 were simulated by Simufact Forming software. The test results show that the diameter of the rivet leg opening, which is the most important parameter affecting the mechanical properties of the joints, shows a first increase and a second decrease with the increase of rivet length, and the Max. tensile loads of the joints have the same variation law. The larger the diameter of the rivet leg opening, the greater the Max. tensile load of the joint, and the greater the effective plastic strain of the rivet of the joint. The rivet length of the joints in the five preferred SPR formation schemes obtained were all 6.5 mm, and only one scheme had a rivet hardness of H4, the rest were H5. The SPR experiment is used to verify the current finite element simulation data can get the final research conclusion. The finite element simulation (FEM) would greatly reduce the test times of the SPR test, save the test consumables and save the test cost.

Submerged arc welding process: enhancement of production performance based on metallurgical observations

Welding processes are widely used technologies in the industrial context for creating permanent connections between mechanical components. This popularity is due to their versatility, which arises from the numerous available process variants and the multiple advantages they offer compared to other joining techniques. In the manufacturing context, where devices often operate in extreme conditions, the quality of welds becomes a critical factor in ensuring the safety and reliability of the manufactured products. Furthermore, a sound joint requires careful compliance with the increasingly stringent design specifications demanded by customers who require industry-standard conformity in order to achieve defect-free, robust, and durable welds. To address these needs and to define the optimal roadmap for the investigated process condition, an experimental investigation was conducted on the submerged arc welding process. The experimental trials involved butt joints of ASTM A516 Gr.70 carbon steel plates with different thicknesses in a flat position, utilizing a U-shaped chamfer and a multi-pass welding technique. For each weldment, the effects of the main process parameters on the qualitative characteristics of the manufactured products were evaluated from a metallurgical perspective. This evaluation included an in-depth metallographic analysis of the heat-affected zone of the carbon steel joint and involved both the measurement of the dimensions of these areas as well as the amount of ferrite and pearlite that resulted as the phases observed in the final microstructure of the steel joint following its solidification. Furthermore, the joint quality was assessed with regard to mechanical strength through hardness measurements. By analysing the experimental data, the paper provides a valuable contribution for increasing the productivity of the investigated welding process, while simultaneously meeting the specified industrial quality requirements for the products made of medium-thickness carbon steels.

Predicting Weld Quality in Duplex Stainless Steel Butt Joints During Laser Beam Welding: A Hybrid DNN-HEVA Approach

Duplex stainless steel (DSS) welding is critical for producing structures and components in a variety of industries. Because traditional optimization approaches cannot manage the complexity of welding, additional solutions must be investigated. This study addresses the need for a systematic exploration of the welding parameters affecting the quality and performance of DSS butt joints, specifically employing fiber laser welding. This study focuses on butt joints in UNS S32304 and 304L using a fiber laser. Welding process parameters were systematically varied, including laser power, scanning speed, beam diameter, and focal position. To efficiently examine the parameters in the design space, the response surface methodology (RSM) with Box–Behnken design (BBD) was used. The combination of the specific parameter values used in the 7th run (Laser Power: 1600 W, Scanning Speed: 2000 mm/min, Beam Diameter: 1.5 [Formula: see text]m, Focal Position: 30 mm) led to better yield point stress (YPS), maximum tensile stress (MTS), break stress (BS) and reduction in area (RA). ANOVA and lack of fit analysis confirmed the significance of the experiment. In particular, the selected welding parameters significantly influenced all responses. A hybrid machine learning method of deep neural network (DNN) and human eye vision algorithm (HEVA) was used for predicting weld quality during laser beam welding (LBW). The hybrid DNN-HEVA consistently outperformed other optimization methods (RSM-BBD, FNN, CNN, and RNN) across key welding quality parameters. High [Formula: see text]2 values (0.9922, 0.9962, 0.9983, and 0.9907) indicated a strong correlation between predicted and actual values for all calculated responses. Lower RMSE, MSE, and MAE values were also highlighted in the precision of predicted values to the experimental data.

A new method of magnetic pulse welding of dissimilar metal plates using a uniform pressure electromagnetic actuator based on pre-deformation

The magnetic pulse welding method using a uniform pressure electromagnetic actuator can effectively weld dissimilar metal plates. However, the existing uniform pressure welding method leads to serious thinning of the plate at the chamfer, lack of welding at the center, and bulging of the welded sample, which seriously affects the quality of the welded joint. To solve these problems and improve the quality of welded joints, a new uniform pressure welding method of dissimilar metal plates based on pre-deformation was developed in this work. In this study, using the welding of an AA1060 aluminum plate and an SS304 steel plate with a thickness of 1 mm as an example, it was confirmed through numerical simulation and experimental research that the pre-deformation of the flyer plate controlled the impact angle of the central area of the plate, and it effectively suppressed central non-welding and serious bulge issues. Further, the welding method also reduced the height of the cushion blocks on both sides, thus mitigating aluminum plate thinning at the chamfer, ultimately improving the tensile strength of the joint. Additionally, a microscopic observation showed that the welding interface formed a wavy composite interface, and the connection strength was good. This welding method can also be extended to welding other dissimilar metal plates.

Exploring the impact of wire core diameter on microstructure and joint properties in ultrasonic wire harness welding

The present study investigates ultrasonic metal welding to manufacture 10 mm2 copper (Cu) wire joints with different core diameters. The primary purpose of this study is to explore the influence of wire core diameter on the performance of ultrasonic welded joints. Wire core diameter is positively correlated with the peeling resistance of the joint. Superior mechanical properties of the joint are achieved with an increased diameter of the wire core. The peeling strength of the welded joint of two wires with a wire core diameter of 0.25 mm reaches 306.8 N. Examining the welding temperature and assessing the joint's porosity reveals a significant impact of temperature on porosity. However, relying solely on porosity as a criterion for judging the overall forming quality of joints may be insufficient. Scanning electron microscope and energy-dispersive X-ray elemental analysis revealed that certain wires underwent plastic deformation at elevated temperatures without attaining atomic bonding. Additionally, the welded joint exhibits a compact structure externally and a more relaxed structure internally. The upper side of the joint in contact with the briquette and the lower side in contact with the welding head exhibit minimal gaps, while numerous gaps are evident in the middle of the joint. Furthermore, upon examining the fracture morphology, two distinct failure modes are identified at the joint surface of the conductor. The first involves the fracture of the wire core with a completely separated joint surface, resulting in poor mechanical properties of the joint. The second mode entails the ductile fracture of the wire core at the joint surface, indicating good mechanical properties of the joint.

Study on the failure mechanism and mechanical properties of multi-layer hole-drilled self-piercing riveted three-layer steel/aluminum hybrid joints

To promote the application of the three-layer steel/aluminum hybrid sheet in the lightweight vehicle body, the multi-layer hole-drilled self-piercing riveting (MH-SPR) process is proposed. This paper aims to investigate the failure mechanism and mechanical properties of three-layer MH-SPR joints and explore the effects of overlap type and pre-drilled layer on forming quality, mechanical properties, failure modes, and fracture characteristics of the three-layer MH-SPR joint in detail. Three overlap types (e.g., type A, type B, and type C) and three pre-drilled layers (e.g., J0, J1, and J2) are designed for the experimental study and the shear experiments and full-field strain measurements are carried out. The results show that the pre-drilled layer can improve SPR joinability and reduce the peak force and energy consumption during the riveting process. Overlap types A and C can increase the peak force of the joint and type C can simultaneously enhance the peak force and energy absorption of the joint. The increase in the pre-drilled layer can increase the peak force and energy absorption of the joint. The overlap types and pre-drilled layers change the failure modes of the joints, which include five types of failure modes: middle sheet tearing, top sheet tearing, rivet fracture, interlock failure, and mixed failure. Full-field strain analysis shows that the overlap type improves the mechanical properties of the joints by altering the deformation mode of the steel sheet. This work provides a theoretical basis for expanding the industrial practice of the MH-SPR process and improving the joined quality of the three-layer joint.

Atmospheric-pressure plasma jet texturing of C/C composites for improved joint strength

This study explores the use of air-fed atmospheric pressure plasma jets (APPJs) as a pre-joining treatment for 3D carbon fiber-reinforced carbon matrix composites (C/C) with the aim of both creating a textured surface that resembles a brush structure and improving the joint strength.The effects of various treatment time lengths on the mass loss, etching depth, and surface texture were investigated using SEM and confocal microscopy. An optimal process time of 30 s was selected, while keeping the other process parameters fixed (air flow of 1750 l/h and nozzle-sample distance of 5 mm). Wetting tests were conducted at 1000 °C, on both untreated and pre-treated C/C surfaces by means of liquid TiCuNi brazing alloy, and low contact angles of about 20° were measured. C/C–TiCuNi–C/C and C/C–TiCuNi–Cu joints were then produced, and their interfacial reactivity was evaluated. The apparent shear strength measured for the APPJ-treated C/C–Cu joints was 140 % higher than the value recorded for the untreated joints, thus confirming the effectiveness of the treatment.Even though a further investigation is needed in which an optimization of the process parameters should be included, this preliminary study has revealed the viability of APPJ as a promising technique to enhance the bonding of C/C composites in dissimilar assemblies and to improve the joint quality.

Intermetallic Compounds in Solder Alloys: Common Misconceptions

Intermetallic compounds (IMC) or intermediate phases are formed between two or more metallic elements in many metal alloy systems. During soldering, an IMC is formed at the soldered interface as the molten solder reacts with an element in the substrate. IMCs also can form within the bulk solder as the joint solidifies. IMCs have critical roles in the solder joint quality and reliability. Unlike most metal alloys, an intermetallic compound typically has a fixed stoichiometry and is in variance with the conventional phases or constituents in the metal system (e.g., alpha and beta). IMCs have a different crystal structure than any of its constituents and some but never all the characteristics and properties of its constituents. Ductility is an important solder joint property, and the low intrinsic ductility of IMCs is associated with brittle behavior and reliability risk in service. However, a review of published solder field failures shows little evidence that IMC properties or IMC evolution under service conditions reduce solder joint reliability. Most IMC-induced solder joint failures are found to result from incorrect material specification or uncontrolled soldering processes. This paper describes the IMCs that occur typically in eutectic, Sn63Pb37 solder and near-eutectic SAC305 or other tin-based Pb-free solder alloys, including how they impact solder joint reliability. The paper also describes the potential impact of IMCs on the solder joint reliability for the newest generation of Pb-free high-performance solder alloys.

Effects of recrystallization on interfacial microstructure evolution and shear strength of TiAl alloy joints

The effects of dynamic recrystallization (DRX) and post-bonding heat treatment (PBHT) on the interfacial microstructure evolution and mechanical properties enhancement of Ti-43Al-4Nb-1Mo-0.2B alloy joints, subjected to various bonding parameters, were thoroughly investigated through detailed microstructural characterization and shear performance tests. A strip-like DRX area was observed at the interface when bonding at 1100 °C, ≥30 MPa, for 60 min. Equiaxial- γ grains underwent discontinuous dynamic recrystallization during the bonding process, and tended to form flat grains parallel to the lamellae direction during recrystallization annealing (1000 °C/6 h) owing to the hindrance imposed by the lamellae on both sides. The orientations of lamellae on the both sides of bonding interface affects the lamellae's stress distribution and deformation behavior at the bonding interface, subsequently influencing the DRX behavior and the width of the DRX zone. Static recrystallization (SRX) during the recrystallization annealing treatment can eliminate bonding defects of joints bonding at lower pressures or temperatures. Optimal joints with fully lamellar interfacial microstructure and excellent shear properties can be obtained through single-α phase annealing treatment. Lamellae microstructure tailored through PBHT can significantly enhance the quality of joints, attributed to the homogeneity of the microstructure between the interface and matrix. The highest shear strength of 478 MPa, accounting for 82 % of the matrix strength, was obtained under the bonding parameters of 1100 °C/30 MPa/60 min-1290 °C/15 min. This work provides important DB process parameters for fabricating of complex structural parts of TiAl alloy.

Online welding status monitoring method of T-joint double-sided double arc welding based on multi-source information fusion

In modern manufacturing, double-sided double arc (DSDA) welding brings advantages in properties and efficiency for T-shaped joints. However, the double-side forming makes it difficult to detect the imperfections and ensure weld joint quality, which few studies have covered. Most existing methods deal with single-arc welding with limited sensing sources. To fill the gap, an online welding status monitoring method for DSDA welding is proposed based on the fusion of welding current, arc voltage, arc sound, and weld pool images. In pre-processing, the automatic weld pool region of interest (ROI) detection method based on the lightweight YOLO-L model and the waveform denoising algorithm are designed. In feature engineering, waveform signals are analyzed in both the time and frequency domain. A weld pool feature extractor based on a convolutional neural network (CNN) is proposed with good effectiveness and interpretability. The output feature combination is refined by Fisher-based selection and evaluation. In model building, an ensemble learning model based on three high-fit basic learners is proposed, with an accuracy of 98.538 %. The proposed model shows significant advantages over the single basic classifier and other ensemble methods. Experiments verify high precision and robustness, laying a foundation for accurate real-time monitoring of DSDA welding production.

Prediction and optimization of joint quality in laser transmission welding using serial artificial neural networks and their integration with Markov decision process

Laser transmission welding is a highly accurate method for joining plastics, but its diverse process parameters require effective modeling for optimal results. Traditional artificial neural networks (ANNs) typically establish predictive models between laser processing parameters and welding strength, neglecting the crucial role of welding morphology in feature extraction, thus diminishing accuracy. To address this, we developed a serial ANN model based on statistically evident correlations, which predicts joint morphology and strength sequentially, resulting in a 47% improvement in predictive accuracy and a mean error of just 7.13%. This two-layered approach effectively reduces the stepwise propagation of errors in ANNs, allowing the first layer to provide a refined data representation for the second layer to predict welding strength. Furthermore, finding the optimal laser parameter set is time-consuming and computationally demanding with traditional ANN-based optimization methods. To address this, we integrated the Markov decision process with the serial ANN for the first time and proposed a novel varying step strategy for the model, enabling a balance of swift convergence and avoidance of suboptimal solutions. Notably, the Markov-serial ANN model attained enhanced optimization results using only 15.5% of the computational resources required by a standard parameter interval optimization methodology. Welding experiments verified the reliability of the Markov-serial ANN, achieving a mean error of 4.54% for welding strength.

DBHF: A double fusion backbone and bidirectional feature hybrid fusion detector for high-precision inspection of avionics solder joint defects

The quality of avionics thermistor wire solder joints has a critical impact on the performance of in-orbit spacecraft. However, it is still hard to simultaneously realize a high-precision inspection of the multi-scale internal and external defects of avionics solder joints. Herein, in combination with active infrared thermography technique, an innovative DBHF detector with a double fusion backbone and a learnable weighted multi-scale bidirectional feature hybrid fusion pyramid network (BdFPN) is demonstrated based on RT-DETR framework. Specifically, the double fusion backbone framework comprises with two lightweight convolutional neural network-based backbones. Compared with conventional single backbone, the double-backbone design forms a multi-level Resnet-like structure, helping to enrich the extracted multi-dimension feature information and retain rich detail information of small-scale defects. The complex learnable weighted multi-scale BdFPN is designed for cross fusion of deep features. One or more additional multi-scale inputs are added to each node involved in feature fusion to aggregate more features from multiple scales and strengthen the interaction between low-level details and high-level semantic information, enabling the detector to make full use of multi-level feature information. Meanwhile, a learnable weight coefficient is set on each node involved in feature fusion and the importance of the input to each node is estimated by training, so that the effective information can be deeply aggregated at different levels. Our DBHF detector achieves a 92.7 % mAP@0.5 on a self-made avionics solder joint dataset with a body size of only 27.2 MB and FPS of 149, outperforming all the typical advanced real-time detectors.

Implementation of external magnetic field to improve strength of St37 steel resistance spot weld

The magnetic assist technique involves the interaction between an external magnetic field and electrical current which produces Lorentz force that influences the flow pattern of molten metal and ultimately impacts the appearance and microstructure of the weld. Many parameters may influence on this process such as welding current, time, and force as well as the working magnet distance (MD). In this study, the effects of the distance between the permanent magnet’s MD on the heat-affected zone (HAZ) and weld nugget zone (NZ) were examined through mechanical and macro- and microstructural analyses. The results demonstrated that MD has a strong influence on the magnetic flux density which determines the joint appearance, quality, and microstructure of St37 steel. Results showed that with increasing MD, HAZ increased from 8 to 22 mm2 while NZ decreased from 26 to 19 mm2, and also, the grain size increased with increasing MD and reaching 48 µm at MD was set to 9 cm. Moreover, hardness decreased at both areas through increasing MD from (120–110) HV at HAZ and from (170–150) HV at NZ. Under the action of (electromagnetic filed) EMF, weld tensile shear strength and the cross tensile strength give the highest values equal to 172 MPa and 155 MPa, respectively, when MD is set to 4.5 cm. Besides, soundness joint was obtained at MD = 4.5 cm which confirms that this is the best distance between magnets.

Design and manufacturing of Welded Vacuum Testing (WVT) tool

To ensure the quality of welded joints in the hull area, welding testing is very important and must be carried out. But unfortunately, currently the quality testing process of welded joints was still limited to penetrant tests and lime tests. The purpose of this study was to obtain a portable welding testing machine that was able to obtain fairly accurate test results on hull welding defects using a vacuum system. The research method is experimental by involving data collection through field experiments, testing is carried out with the resulting weld defect research subjects and the length of testing time on 1G and 3G position welding. The results of the study by compared tests among Welded Vacuum Testing (WVT) machines, Magnetic Particle tests (MP), and Penetrant Tests (PT). The three experiments detected leaking weld defects, spark sparks, pinholes, overlaps, and undercuts. For test results with machines made, welding defects that were successfully detected were leaks in the 1G position welding workpiece and undercut in the 3G position welding workpiece. Air bubbles at a vacuum pressure of 0.2 bar are detected, meaning that there is a defect in the welded joint. This tool can be used in bilge testing.

Application of Friction Riveting technique for the assembly of electronic components on printed circuit boards (PCB)

This study focuses on the effects of reducing the diameter of rivets used in Friction Riveting due to the need for downscaling when joining assemblies on a smaller scale. The Friction Riveting process has shown promising feasibility for a variety of material combinations and applications in the transportation industry. Recent research has explored the potential application of this technique in electronics, specifically for the assembly of printed circuit boards (PCBs), using AA-2024-T351 rivets on thin glass-fiber-reinforced epoxy substrates (FR4). The joint formation of joints produced with PCBs was investigated in terms of process temperature evolution, microstructural changes, and mechanical properties. Joints were obtained at process temperatures ranging from 285 ºC to 368 ºC. The use of 4 mm rivets resulted in extensive delamination, weak joint mechanisms, and cracking, impaired by the different coefficients of thermal expansion of the materials involved. Reducing the rivet diameter to 3 mm significantly improved joint quality. A further reduction to 2.5 mm minimized delamination but led to insufficient anchorage and cracking. Joints produced with a 3 mm rivet diameter achieved the highest ultimate tensile force of 276 N. This study sets the foundation for applying the Friction Riveting process to practical PCB assemblies, demonstrating that optimizing the process parameters to the diameter-to-thickness ratio can balance sufficient rivet anchoring, minimize delamination, and reduce cracking.

Effect of temperature on joint quality in wave soldering of Sn-9Zn-2.5Bi-1.5In lead-free solder alloy

SnZn (tin‑zinc) solder has been regarded as a promising lead-free solder material with a low melting point of 198 °C, serving as a suitable alternative to both SnPb solder due to its lack of hazardous substances and Sn-Ag-Cu solder because of the high cost associated with silver. Nonetheless, its susceptibility to oxidation hinders solderability and increases soldering defects such as bridging, insufficient fillings, and voids, limiting its use in commercial production. Devices designed with through-hole technology, in contrast to surface-mounted ones, continue to exhibit superior interconnection reliability in such applications. In this investigation on wave soldering, a newly developed lead-free solder, composed of 87% tin, 9% zinc, 2.5% bismuth, and 1.5% indium by weight, was employed under two conditions related to nitrogen content: 1) Ensuring that static oxygen content remained below 3000 ppm. 2) Maintaining soldering section oxygen content below 600 ppm at a conveyor speed of 1200 mm/min. The soldering results were examined at various temperatures of preheating and soldering. It proves that the measured peak temperature of liquid solder TpL over 230 °C makes the bridging defect rate lower than 0.30%. Additionally, setting the peak temperature of solder joint TpZ above 220 °C, along with specific preheating temperatures (105/115/135/145 °C), archives 100% vertical filling without significant voids in the solder joints. Moreover, optimizing wave soldering settings, specifically adjusting the wave soldering setting temperature Ts to 235 °C, conveyor speed vc to 1000 mm/min, resolves soldering defects associated with Sn-9Zn-2.5Bi-1.5In alloy in wave process. Relevance summary1.TpL surpasses 230 °C, the total number of bridging defects per board decreases to fewer than 6, approximately 0.30%. TpZ values of 220 °C or higher results in 100% vertical fill and no significant large voids, demonstrating optimal filling effects2.Under the conditions of TS = 235 °C and vc = 1000 mm/min yield TpL > 230 °C and TpZ > 210.9 °C, it leads to a reduction in bridging defects.3.To maintain flux efficiency and minimize internal voids, an optimal selection of preheating temperatures (105/115/135/145 °C) is demonstrated.4.An integrated nitrogen content-controlled system is utilized to eliminate oxygen from the solder pot, aiming to prevent oxidation.

Metal vapor-induced arc instability in stationary TIG-welding

The stability of the arc in arc welding processes is primarily relevant to the joint quality. However, the influencing factors which determine the arc stability are still partly unknown. Combining arc welding with laser welding enhances arc stability. The laser-induced metal vapor is often named as one stabilizing factor. But this contradicts the presumptions of arc welding researchers who mentioned the metal vapor as a destabilizing factor especially when high amounts are present in the arc. This investigation analyzes the specific influence of metal vapor on arc conductivity as one aspect of arc stability by producing metal vapor using a laser process on a separately placed substrate material. Furthermore, the arc current was varied at a constant metal vapor amount. The investigations show that the metal vapor presence increases the arc voltage by at least 20% and its fluctuation amplitude by at least 51% which was presumed to mean a decreased electrical conductivity and therefore decreased arc stability. The arc instability was lower for higher arc currents at constant metal vapor amounts. Therefore, higher arc currents increase the arc stability of welding arcs in the presence of a constant metal vapor amount.

The Effect of Channel Depth on Joint Quality in Cu/AISI 1040 Materials Joined by Mechanical Locking Method

The Effect of Channel Depth on Joint Quality in Cu/AISI 1040 Materials Joined by Mechanical Locking Method