Yield Strength Of Joints Research Articles

Effects of laser shock peening on microstructure and mechanical properties of TIG welded alloy 600 joints

Abstract Laser shock peening (LSP) is a competitive surface strengthening technology for post-weld treatment. In this work, tungsten inert gas (TIG) welded joints of Alloy 600 were treated by LSP to enhance the mechanical properties. The results showed that the tensile residual stress in weld surface was transformed into the compressive stress state after LSP. LSP treatment caused a significant improvement in microhardness and dislocation density in the weld surface. The tensile strength and yield strength of joints after peening on the full gauge part of tensile samples were increased by 10% and 75%, respectively. However, the fatigue life could be improved much more by only peening on the fusion zone and heat affected zone than that of samples peened on the full gauge part. The peening region played a crucial role on the difference of tensile and fatigue properties due to the residual stress distribution, dislocation strengthening and work hardening induced by LSP.

Application of nanoindentation to evaluate the hardness and yield strength of brass joints produced by FSW: microstructural and strengthening mechanisms

Nanoindentation test was employed to measure the actual hardness and yield strength of the stir zone in the friction stir-welded single-phase brass joints. For this aim, different joints were prepared according to an experimental matrix based on the central composite rotatable design. In this design matrix, the tool rotational speed, tool traverse speed, and tool axial force were the input parameters. The outputs were the hardness and yield strength of the joints. To measure the hardness and tensile strength of the joints, the nanoindentation test was employed. Moreover, electron back scattered diffraction and transmission electron microscopy techniques were used to study the microstructural features. The results showed that by decreasing rotational speed and axial force, and by increasing the traverse speed, the hardness and yield strength of the joints were increased. In other words, lower heat inputs caused higher strength in the joints. Finer grain sizes, larger grain average misorientation amounts, i.e., existence of more dislocations, and greater Taylor factors in the lower heat input joints revealed that the influence of grain boundaries, dislocations, and texture were the origins of better mechanical properties.

Exploring the hybrid metal extrusion and bonding process for butt welding of Al\u2013Mg\u2013Si alloys

The hybrid metal extrusion and bonding (HYB) process is a new solid-state joining technique developed for aluminum alloys. By the use of filler material addition and plastic deformation sound joints can be produced at operating temperatures below 400 °C. The HYB process has the potential to compete with commonplace welding technologies, but its comparative advantages have not yet been fully explored. Here, we present for the first time the results from an exploratory investigation of the mechanical integrity of a 4-mm AA6082-T6 HYB joint, covering both hardness, tensile and Charpy V-notch testing. The joint is found to be free from defects like pores, internal cavities and kissing bonds, yet a soft heat-affected zone (HAZ) is still present. The joint yield strength is 54% of that of the base material, while the corresponding joint efficiency is 66%. The indications are that the HYB process may compete or even outperform conventional welding techniques for aluminum in the future after it has been fully developed and optimized.

Mechanical Qualification of the Hybrid Metal Extrusion & Bonding (HYB) Process for Butt Welding of 4 mm Plates of AA6082-T6

Hybrid Metal Extrusion & Bonding (HYB) is a novel solid state joining technique mainly developed for aluminum alloys. By the use of filler material addition and plastic deformation sound joints can be produced at operational temperatures below 400℃. Here, we present the results from an exploratory investigation of the mechanical integrity of a 4 mm AA6082-T6 HYB joint, covering both hardness, tensile and Charpy V-notch testing of different weld zones. The joint is found to be free from defects like pores, internal cavities and kissing-bonds. Still, a soft heat affected zone (HAZ) is present. The joint yield strength is 54 % of the base material, while the corresponding joint efficiency is 66 %. Therefore, there is room for further optimization of the HYB process. This work is now in progress.

Using the Hybrid Metal Extrusion & Bonding (HYB) Process for Butt Welding of 4 mm Plates of AA6082-T6

Hybrid Metal Extrusion & Bonding is a new solid state joining technique developed for aluminium alloys. By the use of filler material addition and plastic deformation sound joints can be produced at operational temperatures below 400 °C. This makes the HYB process more flexible and less vulnerable to defects compared to conventional solid state processes. Here, we present the results form an exploratory investigation of the mechanical integrity of a 4 mm AA6082-T6 HYB joint, covering both hardness, tensile and Charpy V-notch testing of different weld zones. The joint is found to be free from internal defects like pores, cavities and kissing bonds. Still, a soft heat affected zone (HAZ) is present. The joint yield strength is 54 % of the base material, while the corresponding joint efficiency is 66%. Therefore, there is a potential for further optimization of the HYB process. This work is now in progress.

Numerical Study on the Strength of Pipe Joints

With respect to the collapse behavior of joints in a steel pipe truss structure, in the present study, we carry out numerical analyses using a general-purpose FEM software package on the yield strength and the stress distribution near the connection in order to obtain information on the collapse behavior and the yield strength of joints. -joint and -joint are investigated. It is found that the joint strength is proportional to the th power of thickness of a main tube for various joints with a fixed branch-to-chord diameter ratio . The index changes with and in the range of to 0.91, to 1.55 holds with smaller values corresponding to larger . A compressive axial force along the main tube will reduce the joint strength, and it is also found that the strength-reduction ratio for -joint is almost the same as that for -joint having the same and . Also, the joint strength is influenced by the span length of the main tube. The joint strength decreases as the span length increases. However, the influence is small for small .

Effect of Adhesive Thickness on Joint Strength: A Molecular Dynamics Perspective

Recent studies suggest that adhesion in thin joints depends on several factors including temperature, interface toughness, strain rate, surface roughness of adherends, bondline thickness of adhesives, and many others. Influence of thickness on joint properties is surprising but experimentally well documented without reasonable explanations. In this study, we attempt to address the mechanical behavior of polymer adhesives by molecular dynamics (MD) simulation. We show that interfacial strength of the joints in tensile, shear, or combined loading significantly depends on the coupling strength between adhesives and adherends. Failure of joints is always at the interface when coupling strength is weaker. With stronger interfaces, cohesive failure occurs by cavitation or by bulk shear depending on the loading condition. When joints are loaded in tension, it requires an exceedingly stronger interface to realize pure shear failure, otherwise failure is through interface slip. Under a mixed mode condition, interface slip is difficult to avoid. As long as failure is not at the interface alone, the yield strength of joints improves significantly with the reduction of thickness. Increase in bulk density and change in polymer configurations with the reduction of adhesive thickness are believed to be the two key factors in improving mechanical behavior of adhesives.