scholarly journals The effect of zirconium hydride on the corrosion and mechanical behavior of zirconium base metal: Experimental and simulation studies

2021 ◽  
Vol 6 ◽  
pp. 100166
Author(s):  
M. Karimi ◽  
B. Shayegh boroujeny ◽  
H. Adelkhani
Keyword(s):  
Mechanical Behavior ◽  
Base Metal ◽  
Zirconium Hydride ◽  
Simulation Studies

Experimental and Numerical Evaluation of Fracture Toughness on Electron Beam Welded Joint in Al6061-T6

2016 ◽  
Author(s):  
W. Rekik ◽  
O. Ancelet ◽  
C. Gardin ◽  
F. Hamon
Keyword(s):  
Electron Beam ◽  
Mechanical Behavior ◽  
Yield Stress ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Welded Joint ◽  
Material Behavior ◽  
Failure Assessment ◽  
Tearing Resistance ◽  
Alloy 6061

In order to ensure the integrity of structures, failure assessment is required. In this context, the fracture behavior of an electron beam (EB) welded joint on thick plate of aluminum alloy 6061-T6 used for structural components of experimental nuclear reactors was investigated. In the particular case of welded structures, the tearing resistance is strongly dependent on the mismatch of the welded joint and the local behavior of each metallurgical zone. For a reliable analysis, the tensile mechanical behavior of each position of the welded joint was precisely determined by the use of a new measurement prototype. The toughness behavior under different configurations was then evaluated on CT specimens. From these experimental results a mechanical behavior contrast was highlighted. In fact, the fusion zone presents the lowest yield stress and a gradient is observed in the heat affected zone until the material behavior reaches of the base metal yield stress. On the contrary, the toughness of the welded zone is the highest and decreases strongly in the heat affected zone according to an exponential function until the base metal toughness is reached.

TIG welding-brazing joints of aluminum-stainless steel with different thickness of base metals

2019 ◽  
Vol 116 (4) ◽  
pp. 404
Author(s):  
Huan He ◽  
Wenqin Gou ◽  
Yan Jing ◽  
Sanbao Lin ◽  
Chunli Yang
Keyword(s):  
Stainless Steel ◽  
Mechanical Behavior ◽  
Base Metal ◽  
Base Material ◽  
Tig Welding ◽  
Steel Plates ◽  
Base Metals ◽  
Material Fracture ◽  
Welded Seam ◽  
Different Thickness

The aluminum and stainless steel plates with different thickness (1.5, 3 and 4 mm) were joined by TIG welding-brazing process, respectively. The welding procedures, appearance, microstructures and mechanical behavior of the joints were investigated and analyzed. Results showed that reliable welding-brazing joints could be obtained with appropriate welding procedures. The thicker the base metal, the thicker the intermetallic compound (IMC) layer, and the lower the mechanical properties of the joints. There existed obvious microstructure and strength nonhomogeneity along the interface from the top to the bottom of the joint with 3 mm or thicker base metals. The fracture positions of the joints were different from each other. With 1.5 mm base metal, fracture occurred at the aluminum fusion side. While with 3 mm base material, fracture derived from the IMC layer at the root of the steel groove and subsequently occurred at the welded seam. Using 4 mm base metal, crack located mainly at the brazing interface. The differences of the mechanical behavior of the joints were mainly attributed to the change of IMC thickness.

scholarly journals Assessment of Microstructure and Mechanical Properties of Friction Stir Welded AA2014-O and AA2014-T6 Sheets

2021 ◽  
Author(s):  
Wali Muhammad ◽  
Wilayat Husain ◽  
Anjum Tauqir ◽  
Abdul Wadood ◽  
Hamid Zaigham ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Mechanical Behavior ◽  
Ductile Fracture ◽  
Base Metal ◽  
Weld Joint ◽  
Welded Joints ◽  
Strong Influence ◽  
Friction Stir

Abstract In this study, friction stir welding of AA2014-O and AA2014-T6 aluminum alloy was performed at various welding speeds to evaluate the influence of temper conditions of base metal on the properties of the welded joints. The results showed strong influence of base metal temper conditions on the microstructural morphologies and mechanical behavior of the welded joints. In the 2014-O joints, different zones of weld joint were diffused into each other and there was no clear interface between them. In 2014-T6 joints, there was a distinct demarcation between the NZ, TMAZ, HAZ and base metal. The welded joints in 2014-O temper condition showed increase in hardness in the vicinity of weld center due to grain refinement whereas, in 2014-T6, softening occurred in the same region by the dissolution of strengthening precipitates. The mechanical properties of 2014-O joints were equivalent to the base metal showing a 100% weld efficiency with fracture located in the base metal, whereas 2014-T6 welds exhibited about 70% weld efficiency with fracture located at the NZ/TMAZ interface. All the samples in mechanical testing fractured at retreating side (RS) which exhibited heterogeneity in the mechanical properties of the welded joints. SEM fractographic analysis revealed a ductile fracture mode comprising of dimples in both temper conditions. The size and shape of the dimples was strongly dependent on base metal temper condition.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Evidence for a shear mechanism for the precipitation of γ-zirconium hydride in zirconium

1978 ◽  
Vol 36 (1) ◽  
pp. 658-659
Author(s):  
G.J.C. Carpenter
Keyword(s):  
Elevated Temperature ◽  
Strain Field ◽  
Zirconium Hydride ◽  
Zirconium Atom ◽  
Atom Diffusion ◽  
Solvus Temperature ◽  
Hexagonal Close Packed ◽  
Partial Dislocations ◽  
The Face

In zirconium-hydrogen alloys, rapid cooling from an elevated temperature causes precipitation of the face-centred tetragonal (fct) phase, γZrH, in the form of needles, parallel to the close-packed <1120>zr directions (1). With low hydrogen concentrations, the hydride solvus is sufficiently low that zirconium atom diffusion cannot occur. For example, with 6 μg/g hydrogen, the solvus temperature is approximately 370 K (2), at which only the hydrogen diffuses readily. Shears are therefore necessary to produce the crystallographic transformation from hexagonal close-packed (hep) zirconium to fct hydride.The simplest mechanism for the transformation is the passage of Shockley partial dislocations having Burgers vectors (b) of the type 1/3<0110> on every second (0001)Zr plane. If the partial dislocations are in the form of loops with the same b, the crosssection of a hydride precipitate will be as shown in fig.1. A consequence of this type of transformation is that a cumulative shear, S, is produced that leads to a strain field in the surrounding zirconium matrix, as illustrated in fig.2a.

Benefits from Computerized Adaptive Testing as Seen in Simulation Studies

1999 ◽  
Vol 15 (2) ◽  
pp. 91-98 ◽  
Author(s):  
Lutz F. Hornke
Keyword(s):  
Measurement Error ◽  
Computerized Adaptive Testing ◽  
Test Procedure ◽  
Adaptive Testing ◽  
Parameter Estimates ◽  
Simulation Studies ◽  
Computerized Adaptive Test ◽  
Item Banks ◽  
Item Parameters ◽  
General Reliability

Summary: Item parameters for several hundreds of items were estimated based on empirical data from several thousands of subjects. The logistic one-parameter (1PL) and two-parameter (2PL) model estimates were evaluated. However, model fit showed that only a subset of items complied sufficiently, so that the remaining ones were assembled in well-fitting item banks. In several simulation studies 5000 simulated responses were generated in accordance with a computerized adaptive test procedure along with person parameters. A general reliability of .80 or a standard error of measurement of .44 was used as a stopping rule to end CAT testing. We also recorded how often each item was used by all simulees. Person-parameter estimates based on CAT correlated higher than .90 with true values simulated. For all 1PL fitting item banks most simulees used more than 20 items but less than 30 items to reach the pre-set level of measurement error. However, testing based on item banks that complied to the 2PL revealed that, on average, only 10 items were sufficient to end testing at the same measurement error level. Both clearly demonstrate the precision and economy of computerized adaptive testing. Empirical evaluations from everyday uses will show whether these trends will hold up in practice. If so, CAT will become possible and reasonable with some 150 well-calibrated 2PL items.

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