The high temperature deformation behaviors of α＋β type titanium alloy TC11 （Ti-6.5Al-3.5Mo-1.5Zr-0.3Si） with coarse lamellar starting microstructure were investigated based on the hot compression tests in the tem...The high temperature deformation behaviors of α＋β type titanium alloy TC11 （Ti-6.5Al-3.5Mo-1.5Zr-0.3Si） with coarse lamellar starting microstructure were investigated based on the hot compression tests in the temperature range of 950-1100 ℃ and the strain rate range of 0.001-10 s-1. The processing maps at different strains were then constructed based on the dynamic materials model, and the hot compression process parameters and deformation mechanism were optimized and analyzed, respectively. The results show that the processing maps exhibit two domains with a high efficiency of power dissipation and a flow instability domain with a less efficiency of power dissipation. The types of domains were characterized by convergence and divergence of the efficiency of power dissipation, respectively. The convergent domain in a＋fl phase field is at the temperature of 950-990 ℃ and the strain rate of 0.001-0.01 s^-1, which correspond to a better hot compression process window of α＋β phase field. The peak of efficiency of power dissipation in α＋β phase field is at 950 ℃ and 0.001 s 1, which correspond to the best hot compression process parameters of α＋β phase field. The convergent domain in β phase field is at the temperature of 1020-1080 ℃ and the strain rate of 0.001-0.1 s^-l, which correspond to a better hot compression process window of β phase field. The peak of efficiency of power dissipation in ℃ phase field occurs at 1050 ℃ over the strain rates from 0.001 s^-1 to 0.01 s^-1, which correspond to the best hot compression process parameters of ,8 phase field. The divergence domain occurs at the strain rates above 0.5 s^-1 and in all the tested temperature range, which correspond to flow instability that is manifested as flow localization and indicated by the flow softening phenomenon in stress-- strain curves. The deformation mechanisms of the optimized hot compression process windows in a＋β and β phase fields are identified to be spheroidizing and dynamic recrystallizing controlled by self-diffusion mechanism, respectively. The microstructure observation of the deformed specimens in different domains matches very well with the optimized results.展开更多
The main objective of the present work was to determine the influence of the most important technological variables of CMTP （cyclical mechanic-thermal processing） on the strain hardening in the surface layers of ste...The main objective of the present work was to determine the influence of the most important technological variables of CMTP （cyclical mechanic-thermal processing） on the strain hardening in the surface layers of steel parts. For this, it was designed a full factorial plan at two levels of five independent variables that include the whole processing in two and three cycles, the cold-forming degree and force during the plastic deformation （burnishing）, and the temperature and time at the given temperature during the aging. Each cycle is composed of plastic deformation at room temperature plus aging. As dependent variables, the degree and penetration depth of strain hardening were evaluated. Based on the appropriately used set of experimental data, it had been fitted an exponential model for each dependent variables and also a two-degree polynomial fitting of in-depth evolution of microhardness profile was obtained. The amount of cycles and the cold-forming degree are the technological variables of CMTP that influence the most on strain hardening, although other variables also are significant. The microhardness profile highlights that during the CMTP, the strain hardening decreases from the outer bound to the transition zone of the surface layers, where it disappears.展开更多
基金Project (51005112) supported by the National Natural Science Foundation of ChinaProject (2010ZF56019) supported by the Aviation Science Foundation of China+1 种基金Project (GJJ11156) supported by the Education Commission of Jiangxi Province, ChinaProject(GF200901008) supported by the Open Fund of National Defense Key Disciplines Laboratory of Light Alloy Processing Science and Technology, China
文摘The high temperature deformation behaviors of α＋β type titanium alloy TC11 （Ti-6.5Al-3.5Mo-1.5Zr-0.3Si） with coarse lamellar starting microstructure were investigated based on the hot compression tests in the temperature range of 950-1100 ℃ and the strain rate range of 0.001-10 s-1. The processing maps at different strains were then constructed based on the dynamic materials model, and the hot compression process parameters and deformation mechanism were optimized and analyzed, respectively. The results show that the processing maps exhibit two domains with a high efficiency of power dissipation and a flow instability domain with a less efficiency of power dissipation. The types of domains were characterized by convergence and divergence of the efficiency of power dissipation, respectively. The convergent domain in a＋fl phase field is at the temperature of 950-990 ℃ and the strain rate of 0.001-0.01 s^-1, which correspond to a better hot compression process window of α＋β phase field. The peak of efficiency of power dissipation in α＋β phase field is at 950 ℃ and 0.001 s 1, which correspond to the best hot compression process parameters of α＋β phase field. The convergent domain in β phase field is at the temperature of 1020-1080 ℃ and the strain rate of 0.001-0.1 s^-l, which correspond to a better hot compression process window of β phase field. The peak of efficiency of power dissipation in ℃ phase field occurs at 1050 ℃ over the strain rates from 0.001 s^-1 to 0.01 s^-1, which correspond to the best hot compression process parameters of ,8 phase field. The divergence domain occurs at the strain rates above 0.5 s^-1 and in all the tested temperature range, which correspond to flow instability that is manifested as flow localization and indicated by the flow softening phenomenon in stress-- strain curves. The deformation mechanisms of the optimized hot compression process windows in a＋β and β phase fields are identified to be spheroidizing and dynamic recrystallizing controlled by self-diffusion mechanism, respectively. The microstructure observation of the deformed specimens in different domains matches very well with the optimized results.
文摘The main objective of the present work was to determine the influence of the most important technological variables of CMTP （cyclical mechanic-thermal processing） on the strain hardening in the surface layers of steel parts. For this, it was designed a full factorial plan at two levels of five independent variables that include the whole processing in two and three cycles, the cold-forming degree and force during the plastic deformation （burnishing）, and the temperature and time at the given temperature during the aging. Each cycle is composed of plastic deformation at room temperature plus aging. As dependent variables, the degree and penetration depth of strain hardening were evaluated. Based on the appropriately used set of experimental data, it had been fitted an exponential model for each dependent variables and also a two-degree polynomial fitting of in-depth evolution of microhardness profile was obtained. The amount of cycles and the cold-forming degree are the technological variables of CMTP that influence the most on strain hardening, although other variables also are significant. The microhardness profile highlights that during the CMTP, the strain hardening decreases from the outer bound to the transition zone of the surface layers, where it disappears.
