Tensile Properties Of Joints Research Articles

Temperature-dependent pinned joint tensile behavior and failure analysis of CF/PEKK composites

The pinned joint tensile properties and failure behaviors of carbon-fiber-reinforced polyetherketoneketone (CF/PEKK) composites are sensitive to application temperatures. Herein, this study investigated the temperature-dependent mechanical behavior of CF/PEKK composites in a pinned joint configuration, emphasizing the impact on tensile behavior and bearing strength. Utilizing Solvay’s CF/PEKK prepreg with a quasi-isotropic stacking sequence, tensile tests were conducted at [Formula: see text]C and 230∘C. At [Formula: see text]C, increased load-pin displacement stiffness was observed, attributed to reduced polymer chain mobility, leading to increased peak load and concentrated bearing area around the pin contact region. Conversely, at 230∘C, a substantial reduction in stiffness and peak load was evident, emphasizing the severe deterioration of pin-load strength. Fracture analysis revealed distinct failure modes at different temperatures, highlighting localized compressive failure at [Formula: see text]C and severe permanent bearing failure at 230∘C. Understanding these temperature-dependent behaviors is critical for optimizing CF/PEKK composite applications in diverse industrial settings, providing insights for enhanced performance and reliability. The findings offer valuable information on the material’s behavior under extreme temperature conditions, contributing to the design and application of CF/PEKK composites in various industrial scenarios.

Al4C3 formation and joint tensile properties of dual-beam laser butt welding SiCp/6005A composite with filler wires

SiC-reinforced aluminum metal matrix composite (SiC/Al MMC) is one of the most promising structural materials that provide excellent specific modulus and weight reduction for industrial applications. When fusion welding of SiC-reinforced Al MMC, however, mechanical properties of SiC/Al MMC were significantly deteriorated due to the formation of brittle Al4C3. In this paper, a dual-beam laser welding process was developed to laser weld SiCp/6005A Al composite with ER4043 and ER5356 filler wires. The morphology, microstructure, tensile properties, and fracture behaviors of the welded joints were investigated. Compared to ER5356 filler wire, the weld quality was improved by ER4043, including better surface quality, fewer weld defects, higher tensile strength and better ductility. By introducing the silicon element of ER4043 filler wire into the molten pool, the size and amount of brittle Al4C3 compounds and the porosities were reduced and the reaction between liquid Al and reinforced SiC particles was suppressed to some extent. Furthermore, the dual laser beam energy ratio was optimized to 90%:10% (90/10), the tensile strength of the joints produced with ER4043 was significantly improved to 209 MPa, reaching 70% of the ultimate strength of the base metal.

Microstructure evolution and mechanical properties in the depth direction of ultra-high power laser-arc hybrid weld joint of 316L stainless steel

Ultra-high power laser-arc hybrid welding (LAHW) provides a novel and effective method for joining thick-section with single-pass owing to the advantages of ultra-high penetration and efficiency. However, the evolution of microstructure and properties along penetration direction under ultra-high power LAHW (25 kW-level laser power) are still unclear. In this study, the distribution regularities of microstructure and properties in the depth direction of ultra-high power LAHW joint of 316L stainless steel are explored under the optimal weld formation. Results show that along the penetration direction, the cooling rate exhibits a significantly increasing trend by temperature field simulation. The macroscopic growth direction of δ dendrites changes from “Ʌ” to “→←” and “▪’’, and the microscopic dendrites changes from disordered coarse skeletal to directional fine skeletal and lathy morphology. Besides, the increase in cooling rate in the depth direction refines the grain size and reduces the texture composition types but increases the {001} 〈100〉 texture strength. Notably, “teardrop-like” boundary is formed in the lower layer and shrinkage cavities present in its central zone, the formation mechanism is investigated in detail. Finally, the tensile properties of joints in the depth direction exhibit a decreasing trend. The final fracture of the lower layer is in the weld center due to the existence of shrinkage cavities. This study points out the evolution of microstructure and mechanical properties in ultra-high power LAHW process, which provides a theoretical and experimental basis for regulating the performance of thick plates.

Effect of pulse mode and frequency on microstructure and properties of 2219 aluminum alloy by ultrahigh-frequency pulse Metal-Inert Gas Welding

Based on self-developed ultra high frequency pulse Metal-Inert Gas Welding (UFP-MIG) power source, the ultra-high frequency pulse (UFP) current was studied as an effective way for improving the microstructure and properties of 2219 aluminum alloy joints. The welding pores reduction performance, microstructures, microhardness, and tensile properties of conventional pulsed MIG(CP-MIG) welds and the UFP-MIG welds with different modes and frequencies were investigated. The results indicated that the UFP-MIG process could almost completely eliminate welding porosity in the joints of 2219 aluminum alloy. Compared with CP-MIG welding process, the grain size of the UFP-MIG welding zone was reduced and gradually decreased as the frequency of UFP increased. Similarly, the grain refinement effect also appeared in the heat affected zone (HAZ) near the welds, and the grain size could be reduced by up to 14.85%. Meanwhile, the morphology and uniformity of θ phases and α+θ eutectics along grain boundaries of UFP-MIG welds were also improved. The microhardness in the weld zone and partially melted zone (PMZ) of UFP-MIG weld joints with different modes and frequencies were significantly improved. The highest joint average microhardness occurred at peak pulse mode (PP) with 40 kHz(75.17HV), which was 27.9% higher than that of CP-MIG (58.74HV). The strength and ductility of welded joints were simultaneously improved by UFP-MIG weld process. Fracture analysis results showed that the large reduction of weld pores, the refinement of weld grains, and the lower segregation of Cu element in the eutectic were responsible for the joint tensile properties improvement.

Friction stir welding of dissimilar aluminum alloys AA7075 to AA2014

The joining of dissimilar Al-Cu alloy AA2014-T651 and Al-Zn alloy AA7075-T651 plates was carried out using friction stir welding (FSW) technique and the process parameters were optimized using Taguchi L9 orthogonal design of experiments. The rotational speed, transverse speed, and axial load were the parameters taken into consideration. The optimum process parameters were determined with reference to tensile strength of the joint. The predicted optimal value of tensile strength was confirmed by conducting the confirmation run using optimum parameters. This study shows that defect free, high efficiency welded joints can be produced using a wide range of process parameters and recommends parameters for producing best joint tensile properties. Analysis of variance showed that the axial load is the most dominant factor in deciding the joint soundness while rotational speed and welding speed also played significant roles.

Investigations on the material flow and the influence of the resulting texture on the tensile properties of dissimilar friction stir welded ZK60/Mg–Al–Sn–Zn joints

This work focuses on clarifying the relationship of material flow and texture evolution in friction stir welding (FSW) of magnesium alloys and the influence of the texture on the tensile properties of joints. Two types of material arrangements, with ZK60 or Mg-4.6Al-1.2Sn-0.7Zn alloys at advancing side (AS), were applied for dissimilar FSW. The material flow velocity was calculated based on the flow patterns, and the texture evolution was analyzed by electron backscatter diffraction. The results showed that the metal in the rotation layer was pushed flowing upward by the right-hand thread tool pin with clockwise rotation, and three regions with significantly different flow behavior and texture distribution were formed in stir zone (SZ). The rotation angle of the c-axis of magnesium hexagonal unit cell at each region was consistent with the material flow behavior around the tool pin approximately. The greater the flow velocity and the moving distance of deformation metal, the greater the texture intensity. Moreover, when ZK60 with superior plastic deformability was placed at AS, the relatively higher flow velocity in SZ was produced. This caused the relatively higher texture intensity, which lead to the lower tensile strength of joints. The tensile fracture of both joints with two arrangement types occurred at the interface between SZ and thermo-mechanical affected zone at AS due to the uncoordinated plastic deformation caused by the inhomogeneous severe texture distribution. This investigation can provide a new insight into FSW process optimization of magnesium alloys.

Al-steel dissimilar joining: Challenges and opportunities

Al-steel joining has a lot of use in the automotive and aerospace industries since it saves a lot of weight. The materials' physical, thermal, and metallurgical qualities differed significantly, making connecting this combination difficult. This article provides a comprehensive overview of the Al-steel joining processes. The fundamental reason for the problem in fusion joining operations is the formation of a thick intermetallic compound (IMC) layer and additional difficulties related to solidification. The effects of heat input, wettability, and IMC layer on joint formation are summarised in this article. To achieve a good joint, numerous elements like heat generation, IMC formation, and process parameters must be critically balanced in solid-state joining processes. The effects of process parameters in friction stir welding (FSW) techniques on joint's mechanical and metallographic soundness are explored in this work. Because of the steel's higher strength, there have been various attempts to soften it and make it easier to deform in order to improve weld amalgamation. The use of tungsten inert gas (TIG) welding and electrical resistance heating to achieve heat-assisted hybrid friction stir welding has been documented in the literature. The hybrid joining processes are found to be improving the joint's tensile properties.

Investigation of Shoulder diameter to Sheet Thickness (D/T) Ratio on Tensile Properties Friction Stir Welded AA2014-T6 Aluminum Alloy Joints

ABSTRACT 2xxx and 7xxx high strength alloy are well suited for components and structures that include a greater strength ratio and are typically used in the fabrication of fuselage, wing skins. AA2014 is hard to join using a fusion welding process because of its good thermal conductivity, oxidation behaviour and low fusion point, which can easily lead to burn through and porosity. To overcome the above difficulty, friction stir welding (FSW) is used. The formation of sound weld depends on process and tool parameters. The tool shoulder is the most predominant factor. About two-third of heat is generated at the interface of tool and sheet. Hence, in this investigation, the influence of the tool shoulder diameter (D) to sheet thickness (T) ratio on the tensile properties of FSW AA2014 joints was analysed. Five tools with varying D/T ratios (2.0, 2.5, 3.0, 3.5 and 4.0) were used. Microstructure and hardness measurement were performed to correlate strength properties of FSW joints. It is found that the joint welded with a D/T ratio of 3.0 disclosed superior joint tensile properties compared to other D/T ratios. It is mainly due to the development of fine-grained structure in stir zone of D/T 3.0 joints.

Effects of Al-Mg wire replacing Al-Cu wire on the properties of 2219 aluminum alloy TIG-welded joint

The effects of Al–Mg wire replacing Al–Cu wire on the microstructure, microhardness and tensile properties of 2219 aluminum alloy tungsten inert gas (TIG)-welded joints were studied. Comparing joints with Al–Cu wire, the capping welds of joints with Al–Mg wire can be strengthened by the introduction of Mg-containing strengthening phase and the hardness can be significantly improved. However, for joints with Al–Mg wire, both the solidification cracks caused by inappropriate control of alloying element content and the continuous brittle phases at grain boundaries around the weld zone (WZ) can result in the reduced tensile properties. The crack-free weld can be obtained by adjusting the alloying system of WZ. Furthermore, the geometry of WZ also affected the tensile properties of joints with Al–Mg wire.

Improvement on the tensile properties of 2219-T8 aluminum alloy TIG welding joint with weld geometry optimization

An applicable method to improve the tensile properties of 2219-T8 aluminum alloy TIG welding joints is attractive in manufacturing of large propellant tanks. In this work, tensile properties of 2219-T8 TIG welded joints was improved by adjusting the weld geometry using multi -pass welding with swing. The effects of weld geometry on the tensile properties of joint were investigated. And the geometry parameters were optimized by an orthogonal experiment design. The joints with tensile strength coefficient of 70 % and elongation over 4% were acquired after weld geometry optimization. The improvement mechanisms of weld geometry attributed to the reduced strain variation rate and stress concentration at the weld toe.

Investigation on Microstructure and Tensile Properties of High‐Strength AA2014 Aluminium Alloy Welds Joined by Pulsed CMT Welding Process

High‐strength AA 2014 aluminium alloys are broadly employed for many applications because of their good mechanical properties, high strength‐to‐weight ratio, and better resistance to corrosion and are recyclable. The major problems in welding of AA 2014 aluminum alloy using a traditional joining process are partially melted zone, hot cracking, and alloy segregation. Cold metal transfer‐welding (CMT) process is an advanced variant of gas metal arc welding process characterized by reduced heat input in which the welding wire is retracted during the short circuit which allows sufficient time for the weld to cool before placing each drop. In this investigation, the pulsed CMT welding process was chosen to weld high‐strength AA2014 aluminium alloy under T6 condition. The joint tensile properties were compared with the parent material and correlated to the microstructural features. The defect‐free weld was achieved at constant welding speed of 450 mm/min, welding current of 110 A, and electrode feed rate of 5550 mm/min. The joint weld using pulsed CMT yields a maximum strength of 303 MPa, extending joint efficiency up to 67%. It mainly refers to the beneficial effects of welding wire pulsing and dip and retreat motion which causes refining of dendritic grains in weld metal and enhances the strength of joints.

Microstructural characteristics and tensile properties of gas tungsten constricted arc (GTCA) welded Inconel 718 superalloy sheets for aeroengine components

Abstract Inconel 718 is a nickel-based superalloy, typically used in high temperature aerospace applications due to its exceptional mechanical properties and weldability. However, it is susceptible to solute segregation and coarser interconnected laves phase evolution in weld metal due to the high heat input in the gas tungsten arc welding (GTAW) process which drastically reduces the tensile properties of welded joints. It is also susceptible to HAZ microfissuring and liquation cracking issues owing to the evolution of low melting temperature eutectic film at the grain boundaries. To overcome this problem, a newly emerged novel gas tungsten constricted arc welding (GTCAW) process, principally differentiated by magnetic arc constriction and high frequency accentuation of the arc, is used to join Inconel 718 superalloy. The primary objective of this investigation is to evaluate the microstructural characteristics and tensile properties of GTCA welded Inconel 718 superalloy sheets (2 mm thick), fabricated using optimized process parameters, and compare its performance with the base metal. Results showed that GTCA welded joints exhibited 99.20 % and 73.5 % of base metal strength and ductility claiming significant advantages over the GTAW process. It is correlated to the grain refinement in the fusion zone and the evolution of finer discrete laves phase in interdendritic areas of the weld. The basic mechanism responsible for fusion zone grain refinement and corresponding influence on tensile properties of joints is also discussed in brief with regard to the mechanics of arc constriction and pulsing.

Microstructural characteristics and tensile properties of gas tungsten constricted arc (GTCA) welded Inconel 718 superalloy sheets for aeroengine components

Abstract Inconel 718 is a nickel-based superalloy, typically used in high temperature aerospace applications due to its exceptional mechanical properties and weldability. However, it is susceptible to solute segregation and coarser interconnected laves phase evolution in weld metal due to the high heat input in the gas tungsten arc welding (GTAW) process which drastically reduces the tensile properties of welded joints. It is also susceptible to HAZ microfissuring and liquation cracking issues owing to the evolution of low melting temperature eutectic film at the grain boundaries. To overcome this problem, a newly emerged novel gas tungsten constricted arc welding (GTCAW) process, principally differentiated by magnetic arc constriction and high frequency accentuation of the arc, is used to join Inconel 718 superalloy. The primary objective of this investigation is to evaluate the microstructural characteristics and tensile properties of GTCA welded Inconel 718 superalloy sheets (2 mm thick), fabricated using optimized process parameters, and compare its performance with the base metal. Results showed that GTCA welded joints exhibited 99.20 % and 73.5 % of base metal strength and ductility claiming significant advantages over the GTAW process. It is correlated to the grain refinement in the fusion zone and the evolution of finer discrete laves phase in interdendritic areas of the weld. The basic mechanism responsible for fusion zone grain refinement and corresponding influence on tensile properties of joints is also discussed in brief with regard to the mechanics of arc constriction and pulsing.

Influence of arc constriction current (ACC) on microstructural evolution and tensile properties of tungsten inert gas welded thin sheets of aerospace alloy

ABSTRACT The electromagnetic arc constriction technique was implemented to mitigate the heat input related weldability issues in Tungsten Inert Gas (TIG) welding of Alloy 718 particularly solute segregation and substantial laves phase evolution in fusion zone which significantly deteriorates the strength and elongation of welded joints. This paper reports the direct effect of arc constriction current (ACC) on microstructural evolution and tensile properties of Constricted Arc TIG (CA-TIG) welded Alloy 718 joints. ACC is the important parameter which induces the electromagnetic filed and controls the arc constriction characteristics. The basic mechanism responsible for microstructural modification and corresponding influence on the tensile properties of joints is studied both in quantitative and qualitative manner related to the mechanics of electromagnetic arc constriction and correlated to the cooling rate. The joints made by applying ACC of 50 A yielded superior tensile properties. It is correlated to the grain refinement of fusion zone resulting in the evolution of laves phase with finer discrete morphology in interdendritic spacings. Increase in ACC above 50 A causes severe growth of grains in fusion zone and substantial decrement in tensile properties of joints. Beneficial effects of ACC were not perceived at maximum level owing to the high heat input.

Influence of magnetically constricted arc traverse speed (MCATS) on tensile properties and microstructural characteristics of welded Inconel 718 alloy sheets

The magnetically constricted arc technique was implemented to mitigate the heat input related metallurgical problems in Gas Tungsten Arc Welding (GTAW) of Inconel 718 alloy particularly Nb segregation and subsequent laves phase evolution in fusion zone. This paper reports the direct effect of magnetically constricted arc traverse speed (MCATS) on bead profile, tensile properties and microstructural evolution of Inconel 718 alloy sheets joined by Gas Tungsten Constricted Arc Welding (GTCAW) process. The mechanism amenable for the microstructural modification and corresponding influence on the tensile properties of joints is investigated both in qualitative and quantitative manner related to the mechanics of arc constriction and pulsing. It is correlated to the solidification conditions during welding. The relationship between MCATS and Arc Constriction Current (ACC) was derived. Its interaction effect on the magnetic arc constriction and joint performance was analysed. Results showed that the joints fabricated using CATS of 70 mm/min exhibited superior tensile properties (98.39% of base metal strength with 31.50% elongation). It is attributed to the grain refinement in fusion zone microstructure leading to the evolution of finer, discrete laves phase in interdendritic areas.

Comparative analysis between normal and submerged friction stir processed friction stir welded dissimilar aluminium alloy joints

The friction stir welded dissimilar aluminium alloy joints were friction stir processed under air (normal) and underwater (submerged) with room temperature conditions. The joints produced through these two distinct conditions were studied comparatively. The microstructural analysis revealed that due to the water rapid cooling system the grain sizes received were finer compared to the normal friction stir processing ones. The microstructural grain refinement contributed immensely toward the joint tensile properties. The submerged friction stir processed joints were found to be more ductile compared to the normal friction stir processed ones. The positioning of the harder alloy (AA6082) on the advancing side and the soft alloy (AA8011) on the retreating side yielded better results for both normal and submerged conditions. The sampling position was also found to have an impact on the results. This was observed when the specimens cut in the beginning of the joint were studied comparatively with those cut from other locations of the joint.

Mechanical and Microstructural Characterization of Friction Stir-Welded AA2219: TiCp-Reinforced Composites

Light materials having high strength-to-weight ratio plays a vital role in material science especially in the field of aerospace, marine transportation, military and structural applications. Composite serves the same. Aluminium matrix composite (AMC) is the aluminium matrix which has high strength-to-weight ratio. The purpose of the work is to investigate the mechanical properties of welded AA2219 aluminium alloy reinforced with titanium carbide particles (TiCp). Aluminium matrix is reinforced with TiCp using modified stir casting process. Optical colour graphs, XRD and EDX analysis reveal the presence of TiCp in cast AMC. Tensile test shows the ultimate tensile strength increases with the percentage of TiCp addition. Cut samples of size 100 mm X 50 mm X 6 mm cast AMC were friction stir welded using response surface modelling. Ultimate tensile strength and joint efficiency were calculated for the weld samples, and the effects of input parameters were investigated. Experimental results indicate that tool pin profile has a significant effect on tensile strength of friction stir-welded joints followed by welding speed. It is evident from the response that tool rotational speed had the least effect on ultimate tensile strength. The calculated joint efficiency of the most weld samples was more than 90% with respect to the ultimate tensile strength of the base metal. This work ensures defect free, high efficiency welded joints produced using a wide range of process parameters and recommends parameters for producing best joint tensile properties.

Experimental study and taguchi optimization of process parameter on mechanical properties of A319 aluminum alloy using friction stir welding

The main objective of this abstract is to investigate the effect of welding parameters and the mechanical properties in the study of FSW. In this process, the mathematical model was developed by creating the Taguchi design methodology with three parameters, three levels, and 9 runs and it was also used to develop the relationship between those parameters. It can be produced and using a wide range of process parameters and its recommendation for producing the best joint tensile properties. Taguchi Method is used for the optimization of FSW process parameters for the joining of A319 Aluminum alloys. Taguchi method is signal to noise ratio (S/N) analysis that suggests the maximum tensile strength is reached when rotation, traverse speed, and tool pin diameter were chosen as 900 rpm, 40 mm/ min and 5.5 mm pin diameter respectively. ANOVA is used to find out the importance of the parameters. FSW can produce a satisfactory result of 141.05 MPa tensile strength and 112.04 MPa yield strength. FSW can weld A319 plates with a joint efficiency of around 75%.

Effects of Ni powder addition on microstructure and mechanical properties of NiTi to AISI 304 stainless steel archwire dissimilar laser welds

In this study, dissimilar laser welding of NiTi to stainless steel (SS) orthodontic archwires was investigated. As a novel and more operational approach, Ni powder was used as a weld filler metal to improve the properties of joints in laser welding of these alloys. Therefore, welding was performed in two conditions, with and without Ni powder addition, and the results were compared. Optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and focused X-ray diffraction (micro-XRD) analysis were used to study the microstructure, chemical composition and phase characteristics of joints. The Fe-Ni-Ti ternary phase diagram was used as a tool to analyze the phase changes in weld zone with chemical composition variations in two conditions. Results showed that brittle intermetallics such as Fe2Ti and Cr2Ti were formed in zones close to NiTi weld interface in joints without Ni powder addition. However, Ni powder had favorable effects on microstructure, chemical composition and mechanical properties of laser welded joints. In fact, use of Ni powder changed primary solidifying phase region from Fe2Ti to ductile phases of Ni3Ti and γ, and consequently promotes the formation of these ductile phases in the weld zone. Moreover, as a result of chemical composition dilution by Ni, the microstructure of weld zone changed from dendrite to dendrite-cellular structure by suppressing the constitutional undercooling in Ni powder added condition. Furthermore, microhardness tests revealed that the addition of Ni powder caused the average hardness of weld zone to decrease from 580 HV down to 325 HV due to aforementioned intermetallic phase replacement. On the other hand, tensile properties of joints were improved and reached to a tensile strength of 300 MPa and a fracture strain of 2.9 % by adding Ni powder. These values for the welding without Ni powder addition were 150 MPa and, 1.8 %, respectively.

Microstructure, mechanical properties and corrosion behavior of austenitic stainless steel sheet joints welded by gas tungsten arc (GTA) and ultrasonic–wave–assisted gas tungsten pulsed arc (U–GTPA)

Here, ultrasonic–wave–assisted gas tungsten pulsed arc (U–GTPA) welding is proposed as a new alternative welding process to gas tungsten arc (GTA) welding. To better understand the advantages of this new process, in this paper, the microstructure, mechanical properties and corrosion behavior of GTA- and U–GTPA-welded joints of 316L stainless steel are systematically compared. These results show that the weld zone (WZ) depth-to-width ratio of the U–GTPA-welded joint increased, and the area of the equiaxed grain zone was larger than that of the GTA-welded joint. This results in finally increasing the strength and hardness for U–GTPA-welded joints, and the ultimate tensile strength and elongation of the U–GTPA-welded joints were 7.1% and 26.2% greater than those of the GTA-welded joint, respectively. For the U–GTPA-welded joint, under the action of the pulsed arc, the grain distribution with high-angle boundaries (HABs) was different from that of the GTA-welded joint. The minimum of the HAB fraction corresponded to the fracture position for both joints in tensile tests. It shows that a large number of HABs were beneficial in improving joint tensile properties. However, for electrochemical corrosion experiments of two WZs in 3.5% NaCl solution, despite this GTA WZ having a higher HAB fraction, the corrosion current density and corrosion potential of U–GTA WZ were lower and higher than those of the GTA WZ, respectively. The corrosion rate and corrosion sensitivity of U–GTPA WZ indicated good corrosion resistance.