scholarly journals Minimizing Residual Stress in Brazed Joints by Optimizing the Brazing Thermal Profile

2021 ◽  
Author(s):  
Ben Mann ◽  
Kurtis Ford ◽  
Mike Neilsen ◽  
Daniel Kammler
Keyword(s):  
Residual Stress ◽  
Thermal Profile ◽  
Brazed Joints

Active Metal Brazing for Reliable Ceramic Joints Using TiN Coating

2002 ◽  
Vol 17 (1) ◽  
pp. 246-252 ◽  
Author(s):  
Chulsoo Yoon ◽  
Tae Woo Kim ◽  
Osung Seo ◽  
Shinhoo Kang
Keyword(s):  
Residual Stress ◽  
Joint Strength ◽  
Ti Alloy ◽  
Reaction Products ◽  
Tin Coating ◽  
Ceramic Substrates ◽  
Active Metal ◽  
Brazed Joints ◽  
Coated Layer ◽  
The Difference

To improve the strength of brazed joints, a TiN-coated layer was introduced as an interlayer and reaction barrier for ceramic-ceramic joints. Al2O3, Si3N4, and ZrO2 ceramics were brazed with a Ag–Cu–In–Ti alloy after a TiN coating was applied on the ceramic substrates. The strength of as-brazed and thermally treated Al2O3 specimens with a TiN coating was found to be equivalent to that of bulk Al2O3. However, the Si3N4 and ZrO2 systems showed a significant reduction in joint strength. The difference in the strength can be explained on the basis of the bond strength of the coating, the reaction products, and residual stress developed at the joint interfaces.

scholarly journals Study on the Residual Stress Relieving Mechanism of C/C Composite-Nb Brazed Joint by Employing a Structurally Optimized Graphene Reinforced Cu Foam Interlayer

2021 ◽  
Vol 8 ◽  
Author(s):  
Hongliang Li ◽  
Zeyu Wang ◽  
Hassaan Ahmad Butt ◽  
Maocheng Ye ◽  
Hao Chen ◽  
...  
Keyword(s):  
Residual Stress ◽  
Experimental Studies ◽  
Homogeneous Distribution ◽  
Interfacial Structures ◽  
Foam Composite ◽  
Stress Relieving ◽  
Brazed Joints ◽  
Brazed Joint ◽  
The Impact ◽  
Cu Foam

Cu foam has previously been investigated and verified to be an excellent interlayer candidate for relieving high residual stress within C/C composite-Nb brazed joints. However, the optimized geometric structure of Cu foam for brazing has never been properly investigated since it was always employed as a reactant for acquiring homogeneous distribution of the interfacial structures in the brazed joints. In this work, graphene reinforced Cu foam composite (G-Cuf) interlayers were used for brazing C/C composite and Nb. Through the protection effect of graphene on the Cu foam substrate, the impact of porosity and thickness of a structurally intact Cu foam on the joint structure and properties were investigated by finite elemental analysis as well as through experimental studies. By introducing a G-Cuf interlayer with an optimized porosity of 90% and thickness of 0.15 mm, the shear strength of the C/C composite-Nb brazed joint reached 45 MPa, which is 3.5 times higher than that of the joint brazed directly without an interlayer. The strain energy of the brazed joint assisted by G-Cuf interlayer reduced from as high as 10.98 × 10–6 J to 6.90 × 10–6 J, suggesting that the residual stress was effectively mitigated.

TEM investigations of surface residual stress relaxation in A12O3 and Al2O3-SiC nanocomposite

1994 ◽  
Vol 52 ◽  
pp. 628-629
Author(s):  
J. Fang ◽  
H. M. Chan ◽  
M. P. Harmer
Keyword(s):  
Residual Stress ◽  
Single Phase ◽  
Stress Relief ◽  
Stress Recovery ◽  
Surface Residual Stress ◽  
Microscopic Mechanism ◽  
Sic Particles ◽  
Annealing Procedure ◽  
The Difference ◽  
Nano Size

It was Niihara et al. who first discovered that the fracture strength of Al2O3 can be increased by incorporating as little as 5 vol.% of nano-size SiC particles (>1000 MPa), and that the strength would be improved further by a simple annealing procedure (>1500 MPa). This discovery has stimulated intense interest on Al2O3/SiC nanocomposites. Recent indentation studies by Fang et al. have shown that residual stress relief was more difficult in the nanocomposite than in pure Al2O3. In the present work, TEM was employed to investigate the microscopic mechanism(s) for the difference in the residual stress recovery in these two materials.Bulk samples of hot-pressed single phase Al2O3, and Al2O3 containing 5 vol.% 0.15 μm SiC particles were simultaneously polished with 15 μm diamond compound. Each sample was cut into two pieces, one of which was subsequently annealed at 1300° for 2 hours in flowing argon. Disks of 3 mm in diameter were cut from bulk samples.

Residual stress measurements and modeling of built-up Box-T sections

2021 ◽  
Vol 160 ◽  
pp. 107336
Author(s):  
Ziqian Zhang ◽  
Gang Shi ◽  
Xuesen Chen ◽  
Lijun Wang ◽  
Le Zhou
Keyword(s):  
Residual Stress ◽  
Stress Measurements

Comparative study of the effective parameters on residual stress relaxation in welded aluminum plates under cyclic loading

2020 ◽  
Vol 21 (5) ◽  
pp. 505
Author(s):  
Yousef Ghaderi Dehkordi ◽  
Ali Pourkamali Anaraki ◽  
Amir Reza Shahani
Keyword(s):  
Residual Stress ◽  
Cyclic Loading ◽  
Stress Relaxation ◽  
Stress Amplitude ◽  
Cyclic Plasticity ◽  
Mean Stress ◽  
Effective Parameters ◽  
Perfect Plasticity ◽  
Residual Stress Relaxation ◽  
Aluminum Plates

The prediction of residual stress relaxation is essential to assess the safety of welded components. This paper aims to study the influence of various effective parameters on residual stress relaxation under cyclic loading. In this regard, a 3D finite element modeling is performed to determine the residual stress in welded aluminum plates. The accuracy of this analysis is verified through experiment. To study the plasticity effect on stress relaxation, two plasticity models are implemented: perfect plasticity and combined isotropic-kinematic hardening. Hence, cyclic plasticity characterization of the material is specified by low cycle fatigue tests. It is found that the perfect plasticity leads to greater stress relaxation. In order to propose an accurate model to compute the residual stress relaxation, the Taguchi L18 array with four 3-level factors and one 6-level is employed. Using statistical analysis, the order of factors based on their effect on stress relaxation is determined as mean stress, stress amplitude, initial residual stress, and number of cycles. In addition, the stress relaxation increases with an increase in mean stress and stress amplitude.

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