Strength Properties Of Joints Research Articles

Joint Strength Properties of Steel and Aluminum Alloys Dissimilar Materials Resistance Spot Welded Joints with Temperature Distribution Control

In resistance spot welding of Fe-Al dissimilar materials, it is known that intermetallic compounds are formed at the joining interface, and as these compounds thicken, joining strength in the peeling direction decreases. the formation of intermetallic compounds must be suppressed in order to improve joint strength, and one of the control methods is to control the temperature field. Therefore, In this study was to improve joining strength by controlling the temperature field. To control the temperature field, we focused on the current path, make a hole in a polyimide film, known as an insulator, and performed welding with the polyimide film between the electrode and the plate. As a result, it was found that controlling the current path between the Al and the electrode was effective in improving joining strength in the peeling direction. In addition, it was found to affect the formation state of intermetallic compounds, which is a joint property, and the properties of melting zone.

Failure Studies on Adhesive Bonded and Bolted Joints of Natural Fiber Composites

Composites with natural fibers as reinforcements are playing a vital role in recent developments. The present work deals with the fabrication of okra and empty fruit bunch banana fiber polyester matrix composites with varying reinforcement content (5%, 10%, and 15%). Composites were fabricated by using the hand layup technique. After the fabrication process, composites were then adhesively bonded and also joined with bolts. The main objective of this work is to analyse the failure studies on adhesive bonded and bolted joints of okra and empty fruit bunch banana composite specimens. The specimens were tested under tensile load, flexural creep studies, and SEM analysis. It has been observed that empty fruit bunch banana fiber composites exhibited better joint strength properties under tensile loading when compared to the okra fiber composites. To estimate the flexural creep behaviour, all the samples were tested at a constant load of 2.5kg and 5kg. The deflections obtained during regular time intervals (four months) were noted. The presence of internal defects and void content was observed by using the scanning electron microscope. The results showed that adhesive-bonded composites were exhibited less deflection compared to the bolted joints. The empty fruit banana fiber composites exhibited higher creep than okra fiber composites. Decreased creep with the increased fiber has been observed in both cases. SEM Adhesively bonded joints possessing better sustainability as compared to the bolted joints in both the fiber-reinforced composites.

Vacuum brazing of Al2O3 and 3D printed Ti6Al4V lap-joints using high entropy driven AlZnCuFeSi filler

In this work, we studied the brazing characteristics of Al2O3 and 3D printed Ti–6Al–4V alloys using a novel equiatomic AlZnCuFeSi high entropy alloy filler (HEAF). The HEAF was prepared by mechanical alloying of the constituent powder and spark plasma sintering (SPS) approach. The filler microstructure, wettability and melting point were investigated. The mechanical and joint strength properties were also evaluated. The results showed that the developed AlZnCuFeSi HEAF consists of a dual phase (Cu–Zn, face-centered cubic (FCC)) and Al–Fe–Si rich (base centered cubic, BCC) phases. The phase structure of the (Cu–Al + Ti–Fe–Si)/solid solution promises a robust joint between Al2O3 and Ti–6Al–4V. In addition, the joint interfacial reaction was found to be modulated by the brazing temperature and time because of the altered activity of Ti and Zn. The optimum shear strength reached 84 MPa when the joint was brazed at 1050 °C for 60 s. The results can be promising for the integration of completely different materials using the entropy driven fillers developed in this study.

Mechanical and Microstructural Characterization of TIG Welded Dissimilar Joints between 304L Austenitic Stainless Steel and Incoloy 800HT Nickel Alloy

In this article, the mechanical properties and microstructure of 304L austenitic stainless steel/Incoloy 800HT nickel alloy dissimilar welded joints are investigated. The joints were made of 21.3 mm × 7.47 mm tubes using the TIG process with the use of S Ni 6082 nickel filler metal. No welding imperfections were found and high strength properties of joints were obtained, meeting the assumed acceptance criteria of the product’s standards. The tensile strength of the welded joints was higher than for the joined materials (Incoloy 800HT). Macro- and microscopic metallographic tests revealed the correct morphology of the joints and the appropriate structures in their critical zones. However, differences were found in the morphologies of the zones between the weld and the base materials. In fusion boundary from the side of the Incoloy 800HT alloy, no clear outline of the fusion line was observed (type A fusion boundary), while increased grain size and an epitaxial structure were observed. In turn, in the zone: weld–304L steel, a distinct fusion line was observed with areas with an increased amount of high-temperature δ ferrite (type B fusion boundary). No precipitates were found that could reduce the resistance of the joints to intergranular corrosion. A hardness decrease (approximately 30 HV0.1) in the transition zone: austenitic steel–weld and an increase of hardness (approximately 10 HV0.1) on the opposite side of the welded joint were observed.

Effects of Dy substitution for Sn on the solderability and mechanical property of the standard near eutectic Sn–Ag–Cu alloy

In this study, the solderability of Sn–3.5Ag–0.5Cu–xDy solders were investigated and the shear strength properties of joints with Cu substrate were investigated. The results indicated that a small amount Dy addition can improve the solderability, and the optimal amount of Dy was 0.025 wt%. The maximum shear strength can be found with 0.025 wt% Dy addition, improved by 74%. With the observation of the fracture morphology, it was found that a small amount Dy can improve the ductility of the solder joints; but excessive amount of Dy would deteriorate the shear strength and form large dimples on the fracture surface.

Influence of Glue Line Thickness on the Strength of Joints Bonded with PVAc Adhesives

Abstract The purpose of this study was to evaluate the impact of glue line thickness on joint strength properties while using two types of PVAc adhesive (i.e., one-component Rhenocell 3W, 4B Plus, ...

Оксидные включения в швах алюминиевых сплавов, полученных методом сварки трением с перемешиванием

The paper reports the results of the impact of different edge surfaces preparation upon the structure of a metal joint and strength characteristics of welds made by a method a friction welding with mixing. As objects of investigations there were chosen plates made of aluminum alloys 1565, 1201, 1915, V-1341, 1420 and 1460 with 5 mm thick with different edge machining for welding: by stripping and degreasing; by machining, for surface oxide layer removal; by AC and DC welding arc for “growing” a surface oxide layer and the further analysis of its distribution in a metal joint after welding. In the paper there are shown the results of metal joint micro-structure investigation and also test results of welds for strength. Oxide distribution from the surface of edge surfaces inside joint metal and its influence upon strength properties of joints is analyzed.

Selection of the Proper Diffusion Welding Parameters for the Heterogeneous Joint Ti Grade 2/AISI 316L

The creation of the heterogeneous joints at materials with the different physical and mechanical properties is always problematic. As one of methods by which can be achieved very good results is there a diffusion welding. The aim of paper is to show the possibilities of diffusion welding utilization at creation the heterogeneous joints between Titan grade 2 and high-alloyed austenitic steel AISI 316L. The fundamental theory of diffusion and also scheme and realization of experimentally created diffusion welds in the thermal-mechanical simulator Gleeble® 3500 is described in the article. Furthermore, procedure of technological parameters selection when optimization of heterogeneous joint strength properties including metallographic evaluation are taken into account, are also presented.

Laser welding of stainless steel to titanium using explosively welded composite inserts

In paper, weld joints between VT1-0 titanium and AISI 321 austenitic stainless steel using laser welding were obtained. To improve the quality and strength properties of joints, two types (SS–Cu–Nb/Ta–Ti) of explosively welded four-layered composite inserts were used. Barrier layers were different from each other by refractory metal. The effect of intermediate material inserts, in particular tantalum and niobium, on microstructure, chemical composition, strength properties, and fracture behaviour of weld joints was studied. Microstructural studies have revealed two bonding types as results of welding method combination. At copper–stainless steel interface, severely deformed zone characterized by low etch ability was observed. Technological parameter’s optimization provided high joint quality and absence of defects in the weld joints. According to results of strength tests, it was found that the composite insert material affects the strength of the joints. The highest ultimate tensile strength and yield strength were detected for joints containing niobium foil.

The Spot Weldability of Carbon Steel Sheet

The specimens of thickness 0.8 mm carbon steel number 1.8902 in a strip form were welded. The strips of lap joints and curved peeljoints configurations have been welded. The welding parameters such as weld current and weld time have been investigated. The relation between the weld area and the joint strength properties has been presented. The obtained results were showing that the weld joint strength and the molten area (weld nugget volume) highly increase with the increasing of weld current. Therefore, the correlation between the maximum load (joint strength) and area has been given. The reliable weldability under the tensile and shearing loading was considered. Therefore, the new limits of weldability have been presented to consider these two types of loading. Moreover, the experimental results were compared with the empirical relations that consider the sheet thickness only.

Effect of Ti, Nb, and Ti + Nb Coatings on the Bond Strength-Structure Relationship in Al/Al2O3 Joints

There is a growing interest in metal-ceramic bonding for wide range of applications in electronic devices and high technology industry for fabrication of metal matrix composites and bonding of ceramic components to metals. The object of the work was to study the effect of Ti, Nb, and Ti + Nb thin films deposited by PVD method on alumina substrates on structure and bond strength properties of Al/Al2O3 joints. The joints were fabricated using the results of a wetting experiment and the sessile drop method at a temperature of 1223 K in a vacuum of 0.2 MPa for 30 min of contact. The structure of the metal/ceramic interface was investigated using scanning electron microscopy. The elemental distribution at the metal-ceramic interface was analyzed using energy dispersive x-ray spectroscopy. Transmission electron microscopy was also used to investigate some aspects of the metal/ceramic interface. The bond strength properties of joints were measured using shear test. The shear strength results demonstrated significant improvement of shear strength of Al/Al2O3 joints due to the application of Ti + Nb thin film on alumina substrate. Microstructural investigations of the interface indicated that Al/coating/Al2O3 couples have diffusion transition interface which influences the strengthening of these joints. A conclusion could be drawn that the presence of thin film layers changes the character of interaction and leads to the formation of new reaction products in the bonding layer.

Softened zone formation and joint strength properties in dissimilar friction welds

The mechanical properties of dissimilar MMC/AISI 304 stainless steel friction welds with and without silver interlayers were examined. The notch tensile strengths of MMC/AISI 304 stainless steel and MMC/Ag/AISI 304 stainless steel friction welds increased when high friction pressures were applied during the joining operation. The higher notch tensile strengths of dissimilar MMC/AISI and MMC/Ag/AISI 304 stainless steel friction welds resulted from the formation of narrow softened zones in MMC material immediately adjacent to the bondline. The influence of softened zone width and hardness (yield strength) on the notch tensile strengths of dissimilar welds was analysed using finite element modelling (FEM). FEM in combination with the assumption of a ductile failure criterion was used to calculate the notch tensile strengths of dissimilar joints. The key assumption in this work is that dissimilar weld failure wholly depended on the characteristics (mechanical properties and dimensions) of the softened zone formed in MMC material immediately adjacent to the bondline. The modelling results produced based on this assumption closely correspond with the actual notch tensile strengths of dissimilar MMC/Ag/AISI 304 stainless steel and MMC/Ag/AISI 304 stainless steel friction welds.

Effect of surface modifications of leather on its joint strength with polyvinyl chloride

The treatment of bovine leathers with wetting and lyotropic agents followed by heating produced a strengthening of the leathers which increased their joint strength properties to polyvinyl chloride (PVC). A cohesive failure of leather was always obtained. The highest cohesive strength (or point peel strength) was obtained when the treatment was carried out at 140°C with the surfactant NFOE (8.5) (nonylphenol polyoxyethylene with 8.5 mol of oxyethylene). The lyotropic agents (CaCl2, urea) gave very high values (a five-fold increase), whereas the water-dimethyl ketone blends and pure water resulted in a smaller improvement in cohesive strength (a three-fold increase). The improved cohesive strength of leather was mainly due to the destruction of the ordered structure of collagen fibres and to the creation of a complex entanglement network among the collagen fibres. The treatments applied to a bovine leather produced a shrinkage of 65%; the degree of shrinkage was not a function of the kind of treatment, but...

接合組立型Ｓｉ３Ｎ４製ロータの開発

Research and Development of Si3N4 turbo-viscous vacuum pump rotor were conducted. It is difficult to fabricate this type of the rotor by machining of monoblock Si3N4 because it's shape is complex. So, bonded construction in which disks and axle were located by the connection of projection and bore was applied to fabrication after disks and axle were separately sintered and machined.Main results obtained are as follows.(1) 80wt%Cu-20wt%Ti brazing was chosen for bonding method because joint strength properties at room temperature -773 K were excellent.(2) It was predicted by calculation of stress that high stress generated in bonding joint near the connection of projection and bore at high speed rotating. From this calculation result, restriction of bonding area which was not brazed this high stress area was applied so that reliability of rotating characteristic could be raised.(3) Si3N4 turbo-viscous vacuum pump rotor fabricated with above mentioned method rotated by peripheral speed 196 m/s at spin test. From this spin test result, it was confirmed that ceramic vacuum pump rotor could be alterable for metal vacuum pump rotor.

Bearing deflection behaviour of a loaded hole in CFRP

Tests carried out to determine the bearing deflection behaviour of a loaded, torque-tightened bolt in 0° 90°, 0° ± 45° and 90° ± 45° CFRP laminates are described. It has been shown that the optimum bearing stiffness occurs for the same range of 0° ± 45° laminate configurations that exhibit excellent joint strength properties.

Time‐temperature cure behavior of epoxy based structural adhesives

AbstractTime/temperature cure profile diagrams of a nylon‐epoxy adhesive and a rubber‐modified epoxy based structural adhesive have been established from isothermal‐cure time torsional braid analysis measurements. The characteristic zones of liquid, gel‐rubber and glassy state behavior are noted on the diagrams. With the nylon‐epoxy adhesive, the time/temperature cure profile is ill‐defined since all the TBA data had to be obtained (due to the particular curing agent involved) at isothermal conditions above the glass temperature of the finally cured adhesive. In comparison, the rubber‐modified epoxy system showed distinct zones reflecting the various rheological states traversed during the thermosetting process. The dynamic mechanical. (Rheovibron), morphology, and adhesive joint strength properties are examined as a function of cure cycle.