Low Joint Strength Research Articles

Interfacial energy conversion mechanism between 3003 aluminum alloy and 321 stainless steel in vaporizing foil actuator welding process

Conventional welding methods encounter significant challenges, including poor weldability, low joint strength, and the formation of brittle intermetallic compounds, primarily due to the substantial disparities in the physical and chemical properties of aluminum and iron. To mitigate these issues, the vaporizing foil actuator welding (VFAW) process has emerged as a highly promising solid-phase welding technology, particularly suitable for joining dissimilar metals with pronounced differences in properties, such as aluminum alloys and stainless steels. The present study provides an innovative quantitative analysis of the interfacial impact energy conversion mechanisms within the VFAW process. The analysis reveals that the energy responsible for accelerating the flyer workpiece comprises burst vaporization energy (Ed\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E_d$$\\end{document}) and continuous vaporization energy (Ep\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E_p$$\\end{document}), with Ed\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E_d$$\\end{document} identified as the primary energy source, contributing approximately 65–80% of the total energy required for acceleration. Further examination elucidates the mechanisms underlying heat generation and transfer during the interface collision. The investigation identifies the formation of an overheating zone at the interface, attributed to the combined effects of plastic deformation energy and adiabatic shear energy within the flyer workpiece. Consequently, the interface temperature can rise significantly, reaching up to 1394 K, with impact velocities as high as 925 m/s. The analyses contribute to establishing a theoretical foundation for understanding the interface bonding mechanisms characteristic of the vaporizing foil actuator welding method.

A Comparative Study of Microwave Welding Using Multiwalled Carbon Nanotubes and Silicon Carbide Nanowhiskers as Microwave Susceptors

Recently, microwave welding has arisen as an advanced joining method due to its versatility and rapid heating capabilities. Among others, microwave susceptors play a crucial role in microwave welding, as different classes of microwave susceptors have distinct microwave heating mechanisms. In this work, polypropylene (PP) was utilized as a thermoplastic substrate and two types of microwaves susceptors, namely multiwalled carbon nanotubes (MWCNTs) and silicon carbide nanowhiskers (SiC NWs), were studied for microwave welding. The susceptor was first dispersed in acetone to form susceptor suspension. Next, the susceptor suspension was deposited onto the targeted area on substrate and paired with another bare PP substrate. The paired sample was then exposed to 800 W microwave radiation in a microwave oven. Afterward, the welded joint was evaluated using a tensile test and scanning electron microscopy to determine its joint strength and cross-section microstructure. The results showed that the joint strength increased as the heating duration increased. The welded joint formed using MWCNTs achieved a maximum strength of 2.26 MPa when 10 s was used, while the SiC NWs-formed welded joint achieved a maximum strength of 2.25 MPa at 15 s. This difference in duration in forming a complete welded joint can be attributed to the higher microwave heating rates and thermal conductivity of MWCNTs. However, increasing the heating duration to 20 s caused severe deformation at the welded joint and resulted in low joint strength. Overall, this study highlights the significance of understanding the microwave heating mechanism of different susceptors and provides essential insight into the selection of a microwave susceptor for microwave welding.

Design and Performance Study of Carbon Fiber-Reinforced Polymer Connection Structures with Surface Treatment on Aluminum Alloy (6061)

The existing connection methods for aluminum alloy profiles primarily include adhesive bonding and mechanical connections, with metal welding being widely employed. However, metal welding connections exhibit issues such as low joint strength, significant welding deformation, susceptibility to surface oxidation, poor welding surface quality, and challenges in achieving thin-walled metal structures. This paper presents a novel aluminum alloy connection structure that utilizes carbon fiber-reinforced polymer (CFRP) composites to replace welding for connecting aluminum alloy profiles. This innovative aluminum alloy composite connection structure not only enhances connection strength but also addresses the difficulties associated with metal welding. Research indicates that the optimal width of the CFRP structure in the connector is 60 mm, and with synergistic treatment of the aluminum alloy surface, the connection enhancement effect is optimal. Under these conditions, the tensile load can reach 58.71 kN and the bending load can reach 14.33 kN, which are 375.38% and 380.87% higher than those of welded aluminum alloy connections, respectively. The mass-specific strength increases by 106.27% and 134.42%, respectively. Simulations of this connection structure in components demonstrate that it improves strength by 73.99% and mass-specific strength by 71.95% compared to pure metal welded connections. Using ABAQUS 2023 software for simulation and calculation, the difference between the simulation and experimental results is within 5%, verifying the feasibility of the designed structure. This study provides new insights and a theoretical foundation for the development and application of hybrid connection methods involving metal and fiber-reinforced composites.

Modeling failure and instability of a single-jointed rock column based on finite deformation theory

The mechanical behaviour of rock columns is closely tied to factors such as joint development and height-to-width (H/W) ratio. Based on a recently developed finite deformation analysis scheme that can consider both material failure and structural instability of rock columns, uniaxial compression numerical tests of different H/W ratio rock columns containing a single-filled joint were carried out. It analyzes the effects of the strength of joint-filled material (joint strength) and H/W ratio on strength characteristics and failure modes of rock columns. The numerical results indicate that the joint strength controls the joint failure degree, macro-strength, stress distribution, and failure zone range of the rock column. Under different H/W ratios, the macro-strength of the rock column increases in an S-shaped curve with the increase in joint strength. Lower joint strength will accelerate joint failure, resulting in the failure mode of the rock column being joint failure-induced structural instability. As the joint strength and H/W ratio increase, the failure mode of the rock column evolves into the mode of cooperative material-structure-induced collapse and finally develops into structural instability-induced material failure. The research results have a particular reference significance for selecting grout materials for columnar jointed rock mass engineering.

Carbon–Carbon Composite Metallic Alloy Joints and Corresponding Nanoscale Interfaces, a Short Review: Challenges, Strategies, and Prospects

Brazing of carbon–carbon (C/C) composites with metallic materials currently faces a series of difficulties, such as the poor wettability of metallic materials on the surface, the nanoscale interface bonding of C/C composites and metallic materials, thermal stress problems for these different materials, etc. Especially, the practical problems, including the low joint strength and insufficient reliability, still limit the large-scale practical application of brazing technology for C/C composites and metal materials. Herein, in order to guide the fabrication of high-quality joints, we present a brief discussion on the latest research progress in the joints of C/C composites and metallic materials, including current challenges, solution methods, mechanisms, and future prospects. More importantly, the nanoscale interface in the carbon–carbon composites and metallic alloys is paid very little attention, which has been critically discussed for the first time. Then, we further outline the possible solutions in joint problems of C/C composites and metallic materials, proposing feasible strategies to control the reaction in the brazing process, such as surface treatments, the addition of reinforcing phases, a transition layer sandwiched between the base material and the intermediate layer, etc. These strategies are being envisioned for the first time and further contribute to promoting the converged applications of C/C composites and metallic materials.

Experimental studies on automated DC pulsed MIG welding of Monel 400 sheets

ABSTRACTHot-rolled Monel 400 sheets of 2 mm thickness were effectively welded by the automated DC-pulsed gas metal arc welding (DC-pulsed GMAW) process using ERNiCu-7 (NA60) filler. An L9 array has been used in this work to obtain optimal robotic welding parameters to achieve better weld quality. The weldments was subjected to microstructural examinations using optical microscopy. The chemical compounds and elements of the weldments were determined using X-ray diffraction and energy-dispersive analyses. The microhardness and tensile properties of the weldments were evaluated. The corrosion behavior of the base metal and weldments was estimated in service environments by exposing them to a 3.5% NaCl solution using a potentiodynamic polarization method. The weld zone has the highest microhardness value of 154 HV. Monel 400 weldments have lower joint strength and elongation than the base metal. In addition, weldments have a higher corrosion rate (201.1 mm/yr) than base metal (55.64 mm/yr).

Electromigration-enhanced Kirkendall effect of Cu/Ti direct diffusion welding by sparking plasma sintering

Electromigration-enhanced Kirkendall effect is firstly observed in Cu/Ti diffusion welding by sparking plasma sintering. Microstructural evolution and mechanical properties of Cu/Ti joints were systematically investigated to clarify the electromigration-enhanced Kirkendall effect on the mechanism of diffusion joining. Four types of Cu-Ti intermetallic compounds were formed at the interface of bonded joint: CuTi2, CuTi, Cu3Ti2, and β-Cu4Ti. At welding temperature less than 833 K, Cu atomic diffusion was enhanced by current, leading to large Kirkendall Voids along the Cu matrix near intermetallic, resulting in low joint strength. However, as the welding temperature increased to 833 K, a continuous CuTi2 Kirkendall plane was formed in the β-Cu4Ti compound layer, and the growth of the brittle CuTi phase was impeded. A notable observation of this study is that the temperature range for manufacturing high-strength Cu/Ti joints diffusion welding by SPS was determined to be 813–863 K, which is much wider than that reported in the literature. The maximum average shear strength of the joints welded at 833 K was 103.1 MPa, which is twice as large as the value commonly reported. This difference is attributed to the suppression of the brittle CuTi phase by the electromigration-enhanced Kirkendall effect.

Influence of processing innovations on joint strength improvements in friction stir welded high strength copper alloys

One of the major challenges in welding the Cu–Cr–Zr alloys is that the high welding temperature often causes the coarsening of the precipitates, resulting in lower joint strength. Various strategies were studied to reduce the welding temperature below the aging temperature for limiting the precipitate coarsening. The results showed that great challenges existed in reducing the friction stir welding (FSW) temperature below the peak-aging temperature of Cu–Cr–Zr alloy (420–480 °C) without using coolant. Through softening the Cu–Cr–Zr alloys to the supersaturated solid solution state prior to FSW, the peak temperature during FSW of Cu–Cr–Zr alloy under water was reduced to ∼481 °C, which is close to the aging temperate of the Cu–Cr–Zr alloy. After post-weld aging heat treatment, the stir zone exhibited higher hardness than the peak-aged Cu–Cr–Zr alloy due to the combination of the high density of precipitates 10.5 nm in diameter and refined grains 0.65 μm in diameter, enabling the achievement of high joint strength equal to the peak-aged base metal. In addition, the FSW zone also exhibited a high electrical conductivity of 88.9% IACS, which is higher than that of the peak-aged base material (81.0% IACS).

Microstructural and Mechanical Characteristics of 7075-T6 Aluminum Alloy Joint by Double Wire Pulsed Cold Metal Transition Welding

In order to solve the problems of low joint strength and poor welding efficiency in fusion welding of 7075-T6 aluminum alloy, the double wire pulsed cold metal transition (DW-CMTP) welding method was used to weld 7075-T6 aluminum alloy. The microstructural and mechanical characteristics of the joints were analyzed by energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), tensile test and Vickers hardness measurement. The results showed that the DW-CMTP welded joints had good mechanical properties. The highest tensile strength of the joint is 320 MPa without post-weld heat treatment, reaching up to 63% of the basic material. The presence and distribution of micropores in weld joint were manipulate by welding parameters and weakened the joint strength. The fracture location transferred from the heat-affected zone to the fusion zone with the increase of heat input, owing to the change of pore distribution.

Evaluation of welded joints of dissimilar titanium alloy Ti-5Al-2.5Sn and stainless-steel 304 at different multi-interlayer modes

Products manufactured by joining titanium and stainless steel are of great attention to the modern-day industries (aerospace and nuclear) due to their several benefits like high strength, low cost, and corrosion resistance. However, it is difficult to join these alloys owing to the formation of TiFe, Ti2Fe, and TiFe2 compounds which damage their mechanical properties. This study aims to evaluate the microstructural and mechanical properties of titanium alloy Ti-5Al-2.5Sn and stainless steel 304 joints. Joining was performed through pulse–gas tungsten arc welding (P-GTAW) by inserting the Nb-Cu multi-interlayer. The effects of welding speed, two multi-interlayer application modes, and arc offset on the microstructure and mechanical properties such as tensile strength and microhardness were investigated. The mechanical properties were evaluated through tensile and hardness tests while microstructural analysis using scanning electron microscopy (SEM) supported by electron dispersive spectroscopy (EDS). The results revealed that sound and high-quality welds were achieved using a multi-interlayer, which inhibited the formation of TiFe, Ti2Fe, and TiFe2 brittle intermetallic compounds (IMCs). Maximum joint strength of 327 MPa was achieved at a welding speed of 200 mm min−1, mode of multi-interlayer (Nb used as a foil and Cu as a wire) at no arc offsetting, whereas a low joint strength was obtained in the multi-interlayer mode (Nb and Cu both as foils), and arc offset towards SS. The SEM and EDS results revealed that a Cu solid solution was obtained in the fusion zone, which improved the tensile strength. Joint fracture surface analysis indicated that ductile fracture was obtained for high-strength and brittle fracture for the low-strength weld. It is evident that high hardness (400 HV) was obtained at a low welding speed (150 mm min−1) and an arc offset to the stainless steel side owing to the formation of TiCu and Ti2Cu phases, as revealed by the x-ray diffraction phase analysis.

Molybdenum-fiber strengthened brazing of carbon/carbon composite and nickel-based superalloy

The robust and reliable joining of carbon/carbon (C/C) composites and metals has important application value in the aerospace field. However, the low interface bonding strength when joining the two dissimilar materials remains a persistent problem and leads to low joint strength. In this work, a novel interface strengthened brazing process has been developed for joining a C/C composite and a nickel-based superalloy (GH3044). Before joining, high-strength molybdenum (Mo) fibers are planted on the surface of the C/C composite, then the fiber-treated C/C composite is brazed to the GH3044 superalloy using a BNi-2 filler. The results show that a sound joint with robust Mo fibers crossing the interface between the C/C substrate and the brazing layer is obtained. Owing to the pinning effect of the Mo fibers, the joining interface area is increased and cracking is effectively prevented. As a result, the bonded joint exhibits excellent mechanical properties. The maximum shear strength of the joint was measured to be 60 MPa, which is 2.14-times that of the joint without fiber-planting. The maximum three-point bending strength of the joint was measured at 31 MPa, which is 2.58-times that of the joint without fiber-planting.

Study on the effect of laser pre-sintering in laser-assisted glass frit bonding

With the rapid development of laser technology, laser-assisted glass frit bonding technology has been widely used in the packaging process of photoelectric devices. Despite its popularity, there still be some defects to affect the bonding performance, such as pores, cracks, non-fusion, and low joint strength. The glass frit should be pre-sintered by furnace or laser before laser-assisted bonding process. The behavior of the glass frit during the laser pre-sintering and laser bonding was studied in detail. It was found that the traditional pre-sintering process by a furnace can be replaced by laser pre-sintering when the thickness of glass frit layer was ca.3 μm. For the glass frit layers with thickness of ca.8 μm, a furnace should be used for pre-sintering firstly, and then the laser was used for re-sintering. The pre-sintering and re-sintering by laser can effectively inhibit the formation of pores in the following bonding process. The joined interfaces were inspected through a digital microscope and energy dispersive spectrometer (EDS). When the glass frit layer was re-sintered by laser, more penetration and less porosity was observed. It was found that the treatment of re-sintering by laser could improve the bonding strength obviously, the maximum bonding energy was 1.1 J/m2. It can conclude that the laser plays a positive role in the pre-sintering process, and the bonding quality is improved fundamentally.

Enhancing the solid-state joinability of A5052 and CFRTP via an additively manufactured micro-structure

An Al alloy (A5052) sheet was joined with a carbon fiber-reinforced thermoplastic (CFRTP) sheet by hot pressing without melting the CFRTP sheet (that is, solid-state joining). A micro-structure was manufactured via laser irradiation of Al-Ti-C powders bedded on the A5052 sheet. The laser irradiation to Al-Ti-C powders generates numerous particle-shaped protrusions additively on the A5052 sheet, which facilitate the infiltration of CFRTP and mechanically interlock with the CFRTP sheet. To determine the optimal conditions for joining A5052 and CFRTP consisting of a polyamide 6 (PA6) matrix, the effects of joining temperature during hot pressing on the interfacial structure and joint strength were investigated. The maximum joint strength was attained at the joining temperature of 210 °C. At lower temperatures, PA6 was not sufficiently softened to infiltrate the micro-structure, resulting in lower joint strengths. At higher temperatures, carbon fibers (CFs) were exposed on the CFRTP surface and inhibited the penetration of PA6 and CFs into the micro-structure, thereby lowering the joint strength. To infiltrate PA6 and CFs into the micro-structure, hot pressing was performed in a gradient temperature field. The proposed process enabled appropriate infiltration of CFs and PA6 into the micro-structure and led to high and stable joint strength. It is expected that using the additively manufactured micro-structure approach proposed herein, the operating windows of various cutting-edge joining processes can be expanded to more moderate and lower energy conditions. • A5052 and CFRTP sheets were joined by hot pressing without melting the CFRTP sheet. • CFRTP sheet and additively manufactured micro-structure were mechanically interlocked. • Maximum infiltrations of PA6 and CFs into the micro-structure occurred at 210 °C. • At higher temperatures, CFs were exposed on the CFRTP surface and inhibited the infiltration of PA6 into the micro-structure. • The joint constructed under a gradient temperature field had high strength.

Experimental study on heat-affected zones of aluminum alloys in flow drill riveting

Flow drill riveting (FDR) is a novel one-step and single-sided joining process. In FDR, a rivet penetrates through workpieces at a high rotation speed and a certain feed rate, which generates heat through friction to soften the local material. However, the frictional heat usually brings a softening effect to heat-treatable aluminum alloys, which results in heat-affected zones in joints. In this work, temperature evolution of AA6061-T6 during FDR was measured and analyzed, which exhibited a nonlinear relationship with time and was characterized by two peaks. According to the temperature evolution, the FDR process was divided into two stages: penetration of rivet (stage 1) and stop of rivet rotation (stage 2). Electron backscatter diffraction and microhardness results show that the first rise of temperature in stage 1 was attributed to friction stir between rivet and workpieces, and the friction stir at contact surface between rivet head and flash on the top surface of the upper workpiece resulted in the second rise of temperature in stage 2, which caused a larger heat affected zone on the upper workpiece. Furthermore, the effects of process parameters (i.e., rotation speed and feed rate) on temperature evolution of AA6061-T6 were investigated. A higher rotation speed results in higher temperatures, a larger heat-affected zone and a greater softening effect on the upper workpiece, while the lower workpiece is less affected, resulting in lower joint strength. A larger feed rate contributes to a smaller heat affected zone on both upper and lower workpieces, resulting in higher joint strength.

An innovative joint interface design for reducing intermetallic compounds and improving joint strength of thick plate friction stir welded Al/Mg joints

Friction stir welding of dissimilar Al/Mg thick plates still faces severe challenges, such as poor formability, formation of thick intermetallic compounds, and low joint strength. In this work, two joint configurations, namely inclined butt (conventional butt) and serrated interlocking (innovative butt), are proposed for improving weld formation and joint quality. The results show that a continuous and straight intermetallic compound layer appears at the Mg side interface in conventional butt joint, and the maximum average thickness reaches about 60.1 µm. Additionally, the Mg side interface also partially melts, forming a eutectic structure composed of Mg solid solution and Al12Mg17 phase. For the innovative butt joint, the Mg side interface presents the curved interlocking feature, and intermetallic compounds can be reduced to less than 10 µm. The joint strength of innovative butt joint is more than three times that of conventional butt joint. This is due to the interlocking effect and thin intermetallic compounds in the innovative joint.

The Influence of Friction Time on the Joint Interface and Mechanical Properties in Dissimilar Friction Welds

The welding of dissimilar materials is one of the challenging issues in thefabrication industry to obtain required quality welds using fusion weldingmethods. However, some processes recently improved interface bondingwith low joint strength. Unfortunately, the major intermetallic compoundscould not alleviate from the joint interface. Alternatively, solid-statewelding methods revealed fewer intermetallics at the joint interface fordissimilar material welds. Among them, friction welding was chosen to joinincompatible materials with the necessary properties successfully. Frictiontime is a critical parameter for obtaining strong welds through frictionwelding, apart from friction pressure, forging pressure, forging time, androtational speed. Variability of friction time can change the strength offriction by changing mechanical properties such as tensile strength. Thischange of tensile strength is typically influenced by the intermixing region,dependent on friction time. In this experiment, carbon steel and stainlesssteel have been friction welded to test the impact of friction time on thejoint interface where the substrate’s faying surface meets. This interfaceconsists of the intermixing region of the two materials on which the frictionwelding is performed. The results showed an interesting variation in tensilestrength, with varying friction time. The width of the intermixing zoneincreased gradually with friction time until and decreased with the furtherincreasing. The strength of the welds obtained was the highest of 730 MPaat a friction time of 4 s and fell as friction time’s increased value after 4 s.

Higher body mass index and body fat percentage correlate to lower joint and functional strength in working age adults

As the prevalence of obesity grows worldwide, it becomes an increasing concern in working populations. Ergonomists are faced with the challenge of accommodating workplace layouts to include this worker demographic. This study investigated the relationship between shoulder and low back isometric joint strengths across body mass index (BMI) groups. Additionally, relationships between body fat percentage (BF%), absolute strength, and strength normalized to body mass were examined. Ninety, healthy, working age participants performed 11 functional and isometric joint strength exertions. BMI group influenced normalized strength, as the obese 2+ (BMI >35.0) group had up to 63.1% lower joint strength than all other BMI groups (p < 0.05). Significant strong to moderate negative linear relationships existed between BF% and normalized strength for both males and females, and relationships were stronger for females. These strength deficits highlight the importance of considering body composition during ergonomics analyses and configuration of occupational tasks.

Strength of self-piercing riveted Joints with conventional Rivets and Rivets made of High Nitrogen Steel

The use of high-strength steel and aluminium is rising due to the intensified efforts being made in lightweight design, and self-piercing riveting is becoming increasingly important. Conventional rivets for self-piercing riveting differ in their geometry, the material used, the condition of the material and the coating. To shorten the manufacturing process, the use of stainless steel with high strain hardening as the rivet material represents a promising approach. This allows the coating of the rivets to be omitted due to the corrosion resistance of the material and, since the strength of the stainless steel is achieved by cold forming, heat treatment is no longer required. In addition, it is possible to adjust the local strength within the rivet. Because of that, the authors have elaborated a concept for using high nitrogen steel 1.3815 as the rivet material. The present investigation focusses on the joint strength in order to evaluate the capability of rivets in high nitrogen steel by comparison to conventional rivets made of treatable steel. Due to certain challenges in the forming process of the high nitrogen steel rivets, deviations result from the targeted rivet geometry. Mainly these deviations cause a lower joint strength with these rivets, which is, however, adequate. All in all, the capability of the new rivet is proven by the results of this investigation.

Design of adhesively bonded lap joints with laminated CFRP adherends: Review, challenges and new opportunities for aerospace structures

Adhesive bonding is one of the most suitable joining technologies in terms of weight and mechanical performance for current carbon fiber reinforced polymer aircraft fuselage structures. However, traditional joint topologies such as single overlap joints induce high peel stresses, resulting in sudden failure and low joint strength when compared to metal adherends. This drawback in using carbon fiber reinforced polymer is hindering their performance and efficiency in full-scale structures where joints are essential.The goal of this paper is to review how the joint design can help to improve the lap shear strength of composite bonded joints, to recognize the challenges that still need to be understood and to give insight into new opportunities. The focus is thereby on means to increase the matrix-dominated out-of-plane strength of the adherend in order to postpone delamination failure, as it is known to be the most prone type of failure of composite bonded joints. The paper is divided in two main parts: firstly, a review of topology-related and material-related design parameters is given and secondly, future opportunities to improve out-of-plane strength of CFRP bonded joints yet to be explored are discussed.

Effect of temperature and friction on necking and thickening for 5A02 aluminum alloy thin-walled tube in differential temperature extrusion

Necking technology was widely used in the airplane pull rod parts. The tube end of airplane pull rod parts made by the traditional technology (such as spinning) was insufficient to thread directly, and it needed to rivet the threaded sleeve, which result in the low joint strength of airplane pull rod parts. Alternatively, a method of necking and thickening for a thin-walled tube using differential temperature extrusion was proposed for the purpose of threading directly. In this work, the effects of temperature and friction during the process of necking and thickening for 5A02 aluminum alloy thin-walled tube were conducted by finite element (FE) simulations and experiments. The simulation results showed that the higher the temperature was and the lower the friction coefficient was, the bigger the thickness of thickening area in the tube end was, which benefited to thread directly. Then, FE simulation was verified to be reliable by experiments. Subsequently, the effect of temperature on the microstructure in the thickening area of the formed workpiece was investigated by the optical microscopy. The microstructural morphology showed the grain size of the thickening area in the formed workpiece coarsened in comparison with the unformed tube when the material was heated at high temperature during the process of necking and thickening of tube. And the higher temperature was, the coarser the grain in the thickening area was. Finally, the reasonable forming temperature and friction was proposed for improving the micro and macro forming quality of the airplane pull rod parts under the necking and thickening process for thin-walled tube.