scholarly journals Mathematical Modeling of Plastic Deformation of a Tube from Dispersion-Hardened Aluminum Alloy in an Inhomogeneous Temperature Field

Crystals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1103
Author(s):  
Oleg Matvienko ◽  
Olga Daneyko ◽  
Tatiana Kovalevskaya

The effect of temperature distribution on a stress–strain state tube made of disperse-hardened aluminum alloy subjected to internal pressure was investigated. The mathematical model is based on equations of physical plasticity theory and principles of mechanics of deformable solids. The results of this investigation demonstrate that varying the outer wall temperature in the range of 200 K at a fixed temperature of the inner wall leads to a significant change in the plastic resistance limit (for the considered tube sizes, this change is approximately 15%). An increase of the tube wall temperature reduces the resistance to plastic deformation. For the same absolute temperature difference between the outer and inner walls, the plastic resistance limit is less for the higher temperature of the inner wall of the tube. A decrease of the distances between the hardening particles at the same volume fraction of second phase leads to a significant increase in the pressure required to achieve plastic deformation of the tube walls. An increase in tube wall temperature reduces the resistance to plastic deformation. For the same absolute temperature difference between the outer and inner walls, the plastic resistance limit is lower for the higher temperature of the inner tube wall. The decrease of the distance between the hardening particles at the same volume fraction of the second phase leads to a significant increase in the pressure required to achieve plastic deformation of the tube walls.

2019 ◽  
Vol 41 (2) ◽  
pp. 127-137 ◽  
Author(s):  
Pieter Verhees ◽  
Abdul Rahman Akhras ◽  
Kevin M. Van Geem ◽  
Geraldine J. Heynderickx

Author(s):  
Larry W. Swanson ◽  
David K. Moyeda

A quasisteady multimode heat-transfer model for boiler concentric-tube overfire air ports has been developed that predicts the effect of geometry, furnace heat source and heat sink temperatures, axial injector wall conduction, and coolant flow rate on the tube wall temperature distributions. The model imposes a radiation boundary condition at the outlet tip of the ports, which acts as a heat source. The model was validated using field data and showed that both the airflow distribution in the ports and tube diameter can be used to control the maximum tube wall temperature. This helps avoid tube overheating and thermal degradation. For nominal operating conditions, highly nonlinear axial temperature distributions were observed in both tubes near the hot outlet end of the port.


Author(s):  
Adewale Olasumboye ◽  
Gbadebo Owolabi ◽  
Olufemi Koya ◽  
Horace Whitworth ◽  
Nadir Yilmaz

Abstract This study investigates the dynamic response of AA2519 aluminum alloy in T6 temper condition during plastic deformation at high strain rates. The aim was to determine how the T6 temper condition affects the flow stress response, strength properties and microstructural morphologies of the alloy when impacted under compression at high strain rates. The specimens (with aspect ratio, L/D = 0.8) of the as-cast alloy used were received in the T8 temper condition and further heat-treated to the T6 temper condition based on the standard ASTM temper designation procedures. Split-Hopkinson pressure bar experiment was used to generate true stress-strain data for the alloy in the range of 1000–3500 /s strain rates while high-speed cameras were used to monitor the test compliance with strain-rate constancy measures. The microstructures of the as received and deformed specimens were assessed and compared for possible disparities in their initial microstructures and post-deformation changes, respectively, using optical microscopy. Results showed no clear evidence of strain-rate dependency in the dynamic yield strength behavior of T6-temper designated alloy while exhibiting a negative trend in its flow stress response. On the contrary, AA2519-T8 showed marginal but positive response in both yield strength and flow behavior for the range of strain rates tested. Post-deformation photomicrographs show clear disparities in the alloys’ initial microstructures in terms of the second-phase particle size differences, population density and, distribution; and in the morphological changes which occurred in the microstructures of the different materials during large plastic deformation. AA2519-T6 showed a higher susceptibility to adiabatic shear localization than AA2519-T8, with deformed and bifurcating transformed band occurring at 3000 /s followed by failure at 3500 /s.


Author(s):  
Stanislav Krymskiy ◽  
Rafis Ilyasov ◽  
Elena Avtokratova ◽  
Oleg Sitdikov ◽  
Anastasia Khazgalieva ◽  
...  

Effects of severe plastic deformation by isothermal сryorolling with a strain of e~2 and subsequent natural and artificial aging on the structure and resistance to intergranular corrosion (IGC) of the preliminary quenched 2024 aluminum alloy of standard and Zr modified compositions were investigated. Increasing the temperature of aging leads to decreasing the alloy IGC resistance due to precipitation of more stable strengthening S-phase (Al2CuMg), rising difference of electrochemical potentials at grain and subgrain boundaries. Zr additions, оn the opposite, significantly increased the alloy IGC resistance in both naturally and artificially aged conditions, reducing its depth and intensity. The main structural factor, influencing the alloy corrosion behavior, is excess phases: their composition, volume fraction and distribution.


1966 ◽  
Vol 3 (7) ◽  
pp. 1144-1146
Author(s):  
E. L. GEERY ◽  
W. R. THOMPSON ◽  
J. H. BEVERIDGE ◽  
W. J. HELM

Author(s):  
Yu Yanzhi ◽  
Zhang Liangbo ◽  
Xu Haichuan ◽  
Chen Duogang ◽  
Dong Gongjun ◽  
...  

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