Submerged friction stir processing(SFSP)with flowing water was employed to alleviate the porosities and coarse-grained structure introduced by wire-arc manufacturing.As a result,uniform and ultrafine grained(UFG)struc...Submerged friction stir processing(SFSP)with flowing water was employed to alleviate the porosities and coarse-grained structure introduced by wire-arc manufacturing.As a result,uniform and ultrafine grained(UFG)structure with average grain size of 0.83μm was achieved with the help of sharply reduced heat input and holding time at elevated temperature.The optimized UFG structure enabled a superior combination of strength and ductility with high ultimate tensile strength and elongation of 273.17 MPa and 15.39%.Specifically,grain refinement strengthening and decentralized θ(Al_(2)Cu)phase in the sample subjected to SFSP made great contributions to the enhanced strength.In addition,the decrease in residual stresses and removal of pores substantially enhance the ductility.High rates of cooling and low temperature cycling,which are facilitated by the water-cooling environment throughout the machining process,are vital in obtaining superior microstructures.This work provides a new method for developing a uniform and UFG structure with excellent mechanical properties.展开更多
In this paper two dimensional elliptic interface problem with imperfect contact is considered,which is featured by the implicit jump condition imposed on the imperfect contact interface,and the jumping quantity of the...In this paper two dimensional elliptic interface problem with imperfect contact is considered,which is featured by the implicit jump condition imposed on the imperfect contact interface,and the jumping quantity of the unknown is related to the flux across the interface.A finite difference method is constructed for the 2D elliptic interface problems with straight and curve interface shapes.Then,the stability and convergence analysis are given for the constructed scheme.Further,in particular case,it is proved to be monotone.Numerical examples for elliptic interface problems with straight and curve interface shapes are tested to verify the performance of the scheme.The numerical results demonstrate that it obtains approximately second-order accuracy for elliptic interface equations with implicit jump condition.展开更多
文摘Submerged friction stir processing(SFSP)with flowing water was employed to alleviate the porosities and coarse-grained structure introduced by wire-arc manufacturing.As a result,uniform and ultrafine grained(UFG)structure with average grain size of 0.83μm was achieved with the help of sharply reduced heat input and holding time at elevated temperature.The optimized UFG structure enabled a superior combination of strength and ductility with high ultimate tensile strength and elongation of 273.17 MPa and 15.39%.Specifically,grain refinement strengthening and decentralized θ(Al_(2)Cu)phase in the sample subjected to SFSP made great contributions to the enhanced strength.In addition,the decrease in residual stresses and removal of pores substantially enhance the ductility.High rates of cooling and low temperature cycling,which are facilitated by the water-cooling environment throughout the machining process,are vital in obtaining superior microstructures.This work provides a new method for developing a uniform and UFG structure with excellent mechanical properties.
基金supported by the National Natural Science Foundation of China(Grants 12261067,12161067,12361088,62201298,12001015,51961031)the Inner Mongolia Autonomous Region"Youth Science and Technology Talents"support program(Grant NJYT20B15)+1 种基金the Inner Mongolia Scientific Fund Project(Grants 2020MS06010,2021LHMS01006,2022MS01008)by the Innovation fund project of Inner Mongolia University of science and technology-Excellent Youth Science Fund Project(Grant 2019YQL02).
文摘In this paper two dimensional elliptic interface problem with imperfect contact is considered,which is featured by the implicit jump condition imposed on the imperfect contact interface,and the jumping quantity of the unknown is related to the flux across the interface.A finite difference method is constructed for the 2D elliptic interface problems with straight and curve interface shapes.Then,the stability and convergence analysis are given for the constructed scheme.Further,in particular case,it is proved to be monotone.Numerical examples for elliptic interface problems with straight and curve interface shapes are tested to verify the performance of the scheme.The numerical results demonstrate that it obtains approximately second-order accuracy for elliptic interface equations with implicit jump condition.
