In this study AA7075/SiC/TiB2 closed-cell Aluminium hybrid composite foam (AHCFs) with different densities was fabricated by top-loaded bottom pouring stir casting technique. This technique uses oyster-shell powders (CaCO3 2.5 wt. % of composite with 60 μm size) as blowing agents and no viscosity-enhancing ingredient. The silicon carbide (SiC 0, 3, 6, 9, and 12 wt. % with 25 μm) and titanium di-boride (TiB2 3 wt. % with particle size 15 μm) are used as primary and secondary reinforcement agents. It has been noted that the addition of TiB2 and SiC enhanced the mechanical properties (modulus of elasticity, yield strength, and plateau strength) of AHCFs. The energy absorption capacity of AHCFs increases with the addition of SiC up to 3 wt. % and a further increase in SiC content leads to the reduction. It is observed that density and cell wall thickness increases with increasing the wt. % of SiC and Cell size and porosity decrease with an increase in wt. %. of reinforcement. It is also noted that Stirring temperature also strongly influenced the microstructural properties of AHCFs, and 750 0 C of stirring temperature is sufficient for aluminium foaming.
In sodium-cooled fast reactors (SFR), grid plate is a critical component which is made of 316 L(N) SS. It is supported on core support structure. The grid plate supports the core subassemblies and maintains their verticality. Most of the components of SFR are made of 316 L(N)/304 L(N) SS and they are in contact with the liquid-metal sodium which acts as a coolant. The peak operating temperature in SFR is 550 ∘ C. However, the self-welding starts at 500 ∘ C. To avoid self-welding and galling, hardfacing of the grid plate has become necessary. Nickel based cobalt-free colmonoy 5 has been identified as the hardfacing material due to its lower dose rate by Plasma Transferred Arc Welding (PTAW). This paper is concerned with the measurement and investigations of the effects of the residual stress generated due to thermal cycling on a scale-down physical model of the grid plate. Finite element analysis of the hardfaced grid plate model is performed for obtaining residual stresses using elastoplastic analysis and hence the results are validated. The effects of the residual stresses due to thermal cycling on the hardfaced grid plate model are studied.
In this paper, plasma transfer arc welding using hard faced material Colmonoy which is deposited on a annular groove of a circular grid plate made up of SS 304 was studied. Hard face deposition made by Plasma Transferred Arc Welding (PTAW) on a annular groove of a grid plate at relatively high temperature, generates residual stresses due to differential shrinkage of the molten deposit, process-induced thermal gradients and difference in coefficients of thermal expansion between the colmonoy deposit and base material SS 304. However, the magnitude and distribution of the residual stresses vary depending on the heat input, deposition process, and the geometry of the component. Finite element analysis of residual stress is performed with commercial FEA package of ANSYS 12.0 which includes moving heat source, material deposit, temperature dependent material properties, metal plasticity and elasticity. Coupled thermo-mechanical analysis is done for welding simulation and the element birth and death technique is employed for simulation of filler metal deposition. Finally residual stress is evaluated so that annealing is performed accordingly to relieve residual stresses in order to carry out fracture analyses thereafter.
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