Effect Of Cyclic Rotating Bending Process On Microstructure And Mechanical Properties Of Al Alloy And Brass Tubes

The hollow structures produced with the metal tubes have many advantages such as light weight,high utilization rate and wide application scope etc.However,the metal tubes produced by traditional methods often accompanied with the grain coarsening,uniform grain distribution,which results in their poor mechanical properties.To refine the microstructure and improve the mechanical properties of the metal tubes,a new concept of severe plastic deformation process of cyclic rotating bending(CRB)process was newly introducedTo study the effect of the CRB process on the evolution of the microstructure and mechanical properties of the metal tubes,the CRB processes with different deformation temperatures,bending angles,deformation times and rotation speeds were performed with the aluminum alloy(6061)tube with polyphase structure and brass(H65)tube with dual phase structure.The tensile test and Vickers hardness test were employed to evaluate the tensile properties and micro-hardness of the tubes,respectively.While the optical microscope and scanning electronic microscope equipped with electron back-scattered diffraction were utilized for the microstructure characterizations.In addition,in order to investigate the deformation behavior and obtain the stress-strain distribution of the metal tubes during the CRB processes,the finite element simulations of the CRB processes of the two kinds of metal tubes were carried out with the same deformation conditions as those in the experiments.Some main point of this paper are as follows:(1)The research current situation of the severe plastic deformation were summarized by referring the latest relevant literatures at home and abroad.The brief introduction of several kinds of typical severe plastic deformation were given.(2)The principle,characteristics and experimental process of the CRB process were introduced.In order to find out the effect of the deformation parameters of the CRB process on microstructure and mechanical properties of the metal tubes,the CRB processes with different deformation temperatures,bending angles,deformation times and rotation speeds were carried out..(3)The effect of process parameters on microstructure and mechanical properties of the two kinds of metal tubes were analyzed to obtain the evolution of the microstructure and mechanical properties of specimens during the CRB processes with different deformation conditions.(4)In order to investigate the deformation behavior and stress-strain distribution of the metal tubes during the CRB process,the simulation of the CRB processes of the two kinds of metal tubes were executed with the finite element method.(5)The plastic strain distribution of the tubes during the CRB processes with different process parameters were obtained by analyzing the FEM simulation results.The relationship between the accumulated effective plastic strain and the reduction of average grain size,as well as the relationship between the accumulated effective plastic strain and the mechanical properities were also acquired by analyzing of the experimental and simulation results.