scholarly journals Effect of Bonding Temperature on Crack Occurrences in Al2O3/SS 430 Joints Using Cu-Based Brazing Alloys

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 752 ◽  
Author(s):  
Hoejun Heo ◽  
Gyulin Kim ◽  
Yoon-Cheol Park ◽  
Keeyoung Jung ◽  
Chung-Yun Kang
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Residual Stresses ◽  
Bonding Temperature ◽  
Microstructural Characterization ◽  
Brazed Joint ◽  
Maximum Residual Stress ◽  
Α Al2o3 ◽  
Solid Liquid ◽  
Measured Hardness

The effect of bonding temperature on crack occurrences in α-Al2O3/SS 430 joints using Cu-based brazing alloys was investigated with emphasis on the microstructural characterization, hardness, and analytical residual stresses of the joints. The brazing was conducted using Cu-7Al-xTi and Cu-7Al-xZr (x = 2.5, 3.5, and 4.5) alloys at 1000 °C and 1080 °C leading to solid–liquid and liquid-state bonding, respectively. Cracks occurred in the joints brazed at 1080 °C irrespective of the alloys, while crack-free joints were obtained at 1000 °C for joints with only Cu-7Al-xZr alloys. Increases in the bonding temperature or utilization of Cu-7Al-xTi alloys led to a formation of brittle Fe-containing intermetallic or Fe-Cr phases in the brazed seams due to the dissolution of Fe from SS 430, which deteriorated the mechanical properties of the brazed seam. Maximum residual stresses of the real brazed joint were obtained by combining the calculated yield strength and measured hardness of the brazed seams. Eventually, when the hardness of the brazed seam was less than 107 Hv, the yield strength was 124 MPa or less and the maximum residual stress generated in the joint corresponded to 624 MPa or less, leading to a crack-free joint.

scholarly journals Influence of Forming Parameters on the Mechanical Behavior of a Thin Aluminum Sheet Processed through Single Point Incremental Forming

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1461
Author(s):  
Muhammad Ilyas ◽  
Ghulam Hussain ◽  
Haris Rashid ◽  
Mohammed Alkahtani
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Residual Stresses ◽  
Strain Hardening ◽  
Incremental Forming ◽  
Single Point ◽  
Strain Hardening Exponent ◽  
Single Point Incremental Forming ◽  
Forming Parameters ◽  
Tool Diameter

Incremental sheet forming (ISF) is an economical process for batch production. This paper investigates post-forming mechanical properties with an emphasis on the relationship between residual stresses, strengths, micro-hardness and the strain-hardening exponent. Moreover, the influence of important process parameters on the post-forming tensile properties and hardness is analyzed. A Taguchi statistical analysis method is applied to study the effect of forming parameters and identify the best combinations to enhance the mechanical properties of the commercial aluminum. The results reveal that direct relationships exist for the plots of: (i) the strain-hardening exponent vs. the post-necking strain and (ii) difference of post-forming strengths vs. the strain-hardening exponent. Furthermore, the post-forming yield strength can be enhanced by 66.9% through the Single Point Incremental Forming (SPIF). Similarly, the ductility can be doubled by conducting the SPIF after performing the annealing of the as-received rolled sheet. In the present study, parts formed at a wall angle (θ) of 40° with a tool diameter (d) of 6 mm exhibit the highest strength. Moreover, most ductile parts will be obtained at ω = 1500 rpm, d = 22 mm and θ = 20°. It has also been shown that the compressive residual stresses are favorable for higher yield strength and improve hardness of the formed parts.

scholarly journals Residual Stress, Microstructure and Mechanical Properties in Thick 6005A-T6 Aluminium Alloy Friction Stir Welds

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 803 ◽  
Author(s):  
Xiaolong Liu ◽  
Pu Xie ◽  
Robert Wimpory ◽  
Wenya Li ◽  
Ruilin Lai ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Yield Strength ◽  
Residual Stresses ◽  
Heat Input ◽  
Electron Backscatter Diffraction ◽  
Weld Zone ◽  
High Heat ◽  
Friction Stir ◽  
High Heat Input

Plates (37 mm thick) of 6005A-T6 aluminum alloy were butt joined by a single-sided and double-sided friction stir welding (FSW). The 3D residual stresses in the joints were determined using neutron diffraction. The microstructures were characterized by a transmission electron microscope (TEM) and electron backscatter diffraction (EBSD). In the single-sided FSW specimen, there were acceptable mechanical properties with a tensile strength of 74.4% of base metal (BM) and low residual stresses with peak magnitudes of approximately 37.5% yield strength of BM were achieved. The hardness is related to the grain size of the nugget zone (NZ), and in this study, precipitations were dissolved due to the high heat input. In the double-sided FSW specimen, there were good mechanical properties with a tensile strength of 80.8% of BM, but high residual stresses with peak magnitudes of approximately 70% yield strength of BM were obtained. The heat input by the second pass provided an aging environment for the first-pass weld zone where the dissolved phases were precipitated and residual stresses were relaxed.

Effect of the Weld Joint Configuration on Stressed Components, Residual Stresses and Mechanical Properties

2014 ◽  
Vol 56 (4) ◽  
pp. 279-284 ◽  
Author(s):  
Bekir Çevik ◽  
Alpay Özer ◽  
Yusuf Özçatalbaş
Keyword(s):  
Mechanical Properties ◽  
Residual Stresses ◽  
Weld Joint ◽  
Joint Configuration

scholarly journals Melt- vs. Non-Melt Blending of Complexly Processable Ultra-High Molecular Weight Polyethylene/Cellulose Nanofiber Bionanocomposite

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 404
Author(s):  
Nur Sharmila Sharip ◽  
Hidayah Ariffin ◽  
Tengku Arisyah Tengku Yasim-Anuar ◽  
Yoshito Andou ◽  
Yuki Shirosaki ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Tensile Strength ◽  
Yield Strength ◽  
Young’S Modulus ◽  
High Molecular Weight ◽  
Melt Processing ◽  
Cellulose Nanofiber ◽  
Melt Blending ◽  
Ultra High Molecular Weight

The major hurdle in melt-processing of ultra-high molecular weight polyethylene (UHMWPE) nanocomposite lies on the high melt viscosity of the UHMWPE, which may contribute to poor dispersion and distribution of the nanofiller. In this study, UHMWPE/cellulose nanofiber (UHMWPE/CNF) bionanocomposites were prepared by two different blending methods: (i) melt blending at 150 °C in a triple screw kneading extruder, and (ii) non-melt blending by ethanol mixing at room temperature. Results showed that melt-processing of UHMWPE without CNF (MB-UHMWPE/0) exhibited an increment in yield strength and Young’s modulus by 15% and 25%, respectively, compared to the Neat-UHMWPE. Tensile strength was however reduced by almost half. Ethanol mixed sample without CNF (EM-UHMWPE/0) on the other hand showed slight decrement in all mechanical properties tested. At 0.5% CNF inclusion, the mechanical properties of melt-blended bionanocomposites (MB-UHMWPE/0.5) were improved as compared to Neat-UHMWPE. It was also found that the yield strength, elongation at break, Young’s modulus, toughness and crystallinity of MB-UHMWPE/0.5 were higher by 28%, 61%, 47%, 45% and 11%, respectively, as compared to the ethanol mixing sample (EM-UHMWPE/0.5). Despite the reduction in tensile strength of MB-UHMWPE/0.5, the value i.e., 28.4 ± 1.0 MPa surpassed the minimum requirement of standard specification for fabricated UHMWPE in surgical implant application. Overall, melt-blending processing is more suitable for the preparation of UHMWPE/CNF bionanocomposites as exhibited by their characteristics presented herein. A better mechanical interlocking between UHMWPE and CNF at high temperature mixing with kneading was evident through FE-SEM observation, explains the higher mechanical properties of MB-UHMWPE/0.5 as compared to EM-UHMWPE/0.5.

scholarly journals Mechanical properties of rotary swaged steel components

2021 ◽  
Author(s):  
Dhia Charni ◽  
Svetlana Ortmann-Ishkina ◽  
Marius Herrmann ◽  
Christian Schenck ◽  
Jérémy Epp
Keyword(s):  
Mechanical Properties ◽  
Residual Stresses ◽  
Strain Curve ◽  
Dynamic Mechanical Properties ◽  
Process Conditions ◽  
Forming Process ◽  
Rotary Swaging ◽  
Surface Residual Stresses ◽  
Near Net Shape ◽  
As Stress

AbstractThe radial infeed rotary swaging is widely used as a diameter reduction forming process of axisymmetric workpieces, improving the mechanical properties with excellent near net shape forming. In the present study, rotary swaging experiments with different parameter setups were performed on steel tubes and bars under different material states and several resulting property modifications were investigated such as stress-strain curve, hardness, fatigue strength and surface residual stresses. The results show a significant work hardening induced by the rotary swaging process and an improvement in the static and dynamic mechanical properties was observed. Furthermore, the hardness distribution was homogenous in the cross section of the rotary swaged workpieces. Moreover, depending on the process conditions, different residual stresses distribution were generated along the surface.

scholarly journals Enhanced lattice distortion, yield strength, critical resolved shear stress, and improving mechanical properties of transition-metals doped CrCoNi medium entropy alloy

RSC Advances ◽  
2021 ◽  
Vol 11 (38) ◽  
pp. 23719-23724
Author(s):  
Md. Lokman Ali
Keyword(s):  
Mechanical Properties ◽  
Shear Stress ◽  
Transition Metals ◽  
Yield Strength ◽  
Lattice Distortion ◽  
Critical Resolved Shear Stress

The effect of transition-metals (TM) addition on the mechanical properties of CrCoNi medium entropy alloys (MEAs) was investigated.

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