In the present work, 6082 Al alloy has been rolled to 40% and 70% thickness reductions at the cryogenic and room temperatures for the improvement in mechanical and fracture toughness properties. All cryorolled samples...In the present work, 6082 Al alloy has been rolled to 40% and 70% thickness reductions at the cryogenic and room temperatures for the improvement in mechanical and fracture toughness properties. All cryorolled samples are subjected to aging at different temperatures, i.e., 140, 160, and 190 ℃ to improve the strength, ductility, and fracture toughness. The microstructures of the cryorolled （CR） and room temperature rolled （RTR） alloy after 40% and 70% thickness reductions are characterized by FE-SEM to reveal the modes of failure. The results show that the starting bulk Al alloy specimen is fractured in total ductile manner, consisting of well-developed dimples over the entire surface. The mechanical properties and fracture toughness of the 70% CR alloy are found better than 70% RTR alloy due to higher dislocations density and formation of sub-grain structures in the CR alloy.展开更多
The texture and mechanical properties of cross-rolled zircaloy-2 at 77 and 300 K were investigated.Crossrolling at 77 K was performed to impart different thickness reductions of 25% and 50%,while at 300 K with 25%,50%...The texture and mechanical properties of cross-rolled zircaloy-2 at 77 and 300 K were investigated.Crossrolling at 77 K was performed to impart different thickness reductions of 25% and 50%,while at 300 K with 25%,50%,75% and 85% reductions to the sample.EBSD analysis of deformed sample showed that near-basal orientation is not deformed completely after 50% rolling reduction.The activation of prismatic silp,{1122} contraction twin and {1012} extension twin were evident from the deformed microstructure at 77 K.The propensity for activation of basal slip〈a〉 at77 K was also observed.The deformation of the sample at 300 K occurs by prismatic,basal 〈a〉 and pyramidal 〈c＋a〉slips,which were predicted by pole figures.After annealing,the tensile strengths（735 and 710 MPa） are almost the same for 50% cryo-cross-rolled and room-temperature cross-rolled zircaloy-2 with almost 2.7% difference in their ductility.KAM analysis of the deformed samples was made to estimate the stored strain energy and dislocation density.Annealing of deformed sample at 673 K for 30 min results in recrystallization,which leads to the formation of ultrafine grains.展开更多
In this work,element free Galerkin method(EFGM)has been used to obtain the solution of edge crack problem under mechanical loads as it provides a versatile technique to model static as well as moving crack problems wi...In this work,element free Galerkin method(EFGM)has been used to obtain the solution of edge crack problem under mechanical loads as it provides a versatile technique to model static as well as moving crack problems without any requirement of remeshing.At first,some techniques are presented for enriching the EFG approximations near the crack tip such as extrinsic and intrinsic enrichment.Extrinsic enrichment involves the addition of solution form to the trial function,whereas the EFG basis is expanded to include few terms from crack tip solution in intrinsic enrichment.Apart from enrichment techniques,four basic techniques of smoothing meshless approximations near nonconvex boundaries are also presented such as diffraction,transparency,see through and wedge model.These techniques are then used for the parameteric analysis of an edge crack problem under mode-1 loading and results obtained using different approaches are compared with each other as well as with exact solution.Among these techniques,the extrinsic PU enrichment technique was found to be more accurate as compared to other approaches.Extrinsic PU enrichment technique has also been used for the analysis of a shear edge crack problem.In all these techniques,the value of mode-1 stress intensity factor and mode-2 stress intensity factor has been evaluated by interaction integral approach.Effect of crack orientation is also studied for different cases.展开更多
文摘In the present work, 6082 Al alloy has been rolled to 40% and 70% thickness reductions at the cryogenic and room temperatures for the improvement in mechanical and fracture toughness properties. All cryorolled samples are subjected to aging at different temperatures, i.e., 140, 160, and 190 ℃ to improve the strength, ductility, and fracture toughness. The microstructures of the cryorolled （CR） and room temperature rolled （RTR） alloy after 40% and 70% thickness reductions are characterized by FE-SEM to reveal the modes of failure. The results show that the starting bulk Al alloy specimen is fractured in total ductile manner, consisting of well-developed dimples over the entire surface. The mechanical properties and fracture toughness of the 70% CR alloy are found better than 70% RTR alloy due to higher dislocations density and formation of sub-grain structures in the CR alloy.
基金BRNS,Bombay for their financial grant to this work (No.BRN-577-MMD)
文摘The texture and mechanical properties of cross-rolled zircaloy-2 at 77 and 300 K were investigated.Crossrolling at 77 K was performed to impart different thickness reductions of 25% and 50%,while at 300 K with 25%,50%,75% and 85% reductions to the sample.EBSD analysis of deformed sample showed that near-basal orientation is not deformed completely after 50% rolling reduction.The activation of prismatic silp,{1122} contraction twin and {1012} extension twin were evident from the deformed microstructure at 77 K.The propensity for activation of basal slip〈a〉 at77 K was also observed.The deformation of the sample at 300 K occurs by prismatic,basal 〈a〉 and pyramidal 〈c＋a〉slips,which were predicted by pole figures.After annealing,the tensile strengths（735 and 710 MPa） are almost the same for 50% cryo-cross-rolled and room-temperature cross-rolled zircaloy-2 with almost 2.7% difference in their ductility.KAM analysis of the deformed samples was made to estimate the stored strain energy and dislocation density.Annealing of deformed sample at 673 K for 30 min results in recrystallization,which leads to the formation of ultrafine grains.
文摘In this work,element free Galerkin method(EFGM)has been used to obtain the solution of edge crack problem under mechanical loads as it provides a versatile technique to model static as well as moving crack problems without any requirement of remeshing.At first,some techniques are presented for enriching the EFG approximations near the crack tip such as extrinsic and intrinsic enrichment.Extrinsic enrichment involves the addition of solution form to the trial function,whereas the EFG basis is expanded to include few terms from crack tip solution in intrinsic enrichment.Apart from enrichment techniques,four basic techniques of smoothing meshless approximations near nonconvex boundaries are also presented such as diffraction,transparency,see through and wedge model.These techniques are then used for the parameteric analysis of an edge crack problem under mode-1 loading and results obtained using different approaches are compared with each other as well as with exact solution.Among these techniques,the extrinsic PU enrichment technique was found to be more accurate as compared to other approaches.Extrinsic PU enrichment technique has also been used for the analysis of a shear edge crack problem.In all these techniques,the value of mode-1 stress intensity factor and mode-2 stress intensity factor has been evaluated by interaction integral approach.Effect of crack orientation is also studied for different cases.
