Influence of thermomechanical treatments （mill annealing, duplex annealing, solution treatment plus aging and triple annealing） on microstructures and mechanical properties of TC4-DT titanium alloy was investigated....Influence of thermomechanical treatments （mill annealing, duplex annealing, solution treatment plus aging and triple annealing） on microstructures and mechanical properties of TC4-DT titanium alloy was investigated. Results showed that thermomechanical treatments had a significant influence on the microstructure parameters and higher annealing and aging temperature and lower cooling rate led to the decrease of the volume fraction of primaryαand the size of prior-βand the increase of the width of grain boundary αand secondary α. The highest strength was obtained by solution treatment and aging due to a large amount of transformedβand finer grain boundaryαand secondaryαat the expense of slight decrease of elongation and the ultimate strength, yield strength, elongation, reduction of area were 1100 MPa, 1030 MPa, 13%and 53%separately. A good combination of strength and ductility has been obtained by duplex annealing with the above values 940 MPa, 887.5 MPa, 15%and 51%respectively. Analysis between microstructure parameters and tensile properties showed that with the volume fraction of transformedβphase and the prior-βgrain size increasing, the ultimate strength, yield strength and reduction of area increased, but the elongation decreased. While the width of grain boundary α and secondary α showed a contrary effect on the tensile properties. Elimination of grain boundaryαas well as small prior-βgrain size can also improve ductility.展开更多
The effects of strength mis-matching on J-integral and failure assessment line (FAL) of electron beam welded thick TC4-DT titanium alloy joints have been investigated.Elastic and elastic-plastic finite elements (FE) c...The effects of strength mis-matching on J-integral and failure assessment line (FAL) of electron beam welded thick TC4-DT titanium alloy joints have been investigated.Elastic and elastic-plastic finite elements (FE) calculations on centre crack tensile (CCT) specimens were made,and the condition of 20% strength mis-matching was considered.The results indicate that the limit load of the joint can be substituted by that of the base metal.The error of substitution is less than 5%.The failure assessment lines for both over-matching and under-matching joints are increasingly close to that of the base metal,with the ratio of weld width to specimen width (H/W) decreasing.Moreover,the failure assessment lines of the joints can be devised using the stress-strain curves of the base metal,which will be convenient for the practical application of engineering展开更多
以TC4-DT钛合金为研究对象,研究不同温度(20,300,500℃)对TC4-DT的摩擦磨损性能的影响。采用HT-500型摩擦磨损试验机对TC4-DT合金进行摩擦磨损实验,分析温度对摩擦因数及磨损率的影响;通过扫描电镜(Scanning electron microscope,SEM)...以TC4-DT钛合金为研究对象,研究不同温度(20,300,500℃)对TC4-DT的摩擦磨损性能的影响。采用HT-500型摩擦磨损试验机对TC4-DT合金进行摩擦磨损实验,分析温度对摩擦因数及磨损率的影响;通过扫描电镜(Scanning electron microscope,SEM)和能谱(Energy dispersive spectrometer,EDS)等方法探究磨痕的形貌和成分变化及磨损机理。结果表明,随着温度的升高,磨损过程中TC4-DT合金表面不断生成氧化膜,摩擦因数从0.493下降到0.298,磨痕不断变窄变浅,磨损率大大降低;磨损机理在20℃时以粘着磨损、磨粒磨损为主,伴随着疲劳磨损;在300,500℃时以剥层磨损和氧化磨损为主,伴随少量的粘着磨损和磨粒磨损。展开更多
A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding. The phase component, microstructure, composition distribution and properties of the composite layer...A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding. The phase component, microstructure, composition distribution and properties of the composite layer were investigated. The composite layer has graded microstructures and compositions, due to the fast melting followed by rapid solidification and cooling during laser cladding. The TiC powders are completely dissolved into the melted layer during melting and segregated as fine dendrites when solidified. The size of TiC dendrites decreases with increasing depth. Y2O3 fine particles distribute in the whole clad layer. The Y2O3 particle enhanced Ni/TiC composite layer has a quite uniform hardness along depth with a maximum value of HV1380, which is 4 times higher than the initial hardness. The wear resistance of the Ti alloy is significantly improved after laser cladding due to the high hardness of the composite coating.展开更多
研究了双重退火热处理对经不同的拉伸条件变形后的TC4-DT钛合金组织的影响。结果表明:双重退火后得到的组织与拉伸变形条件和第一重退火温度有关。当经最佳的应变速率5.6×10-4s-1和变形温度920~980℃变形后,随第一次退火温度升高,...研究了双重退火热处理对经不同的拉伸条件变形后的TC4-DT钛合金组织的影响。结果表明:双重退火后得到的组织与拉伸变形条件和第一重退火温度有关。当经最佳的应变速率5.6×10-4s-1和变形温度920~980℃变形后,随第一次退火温度升高,显微组织中次生α相析出量增加;在980℃变形后,经过双重退火后的合金组织可以得到编织紧密的网篮组织,且第一重退火温度在β单相区时得到的网篮组织的针状α相更加细长。当经最佳的变形温度940℃和不同的应变速率5.6×10-2~5.6×10-4s-1变形后,经过930℃/1 h AC+540℃/4 h AC双重退火的组织可以得到双态组织,而经过980℃/1 h AC+540℃/4 h AC双重退火的组织为魏氏组织。展开更多
基金Project(51101119)supported by the National Natural Science Foundation of China
文摘Influence of thermomechanical treatments （mill annealing, duplex annealing, solution treatment plus aging and triple annealing） on microstructures and mechanical properties of TC4-DT titanium alloy was investigated. Results showed that thermomechanical treatments had a significant influence on the microstructure parameters and higher annealing and aging temperature and lower cooling rate led to the decrease of the volume fraction of primaryαand the size of prior-βand the increase of the width of grain boundary αand secondary α. The highest strength was obtained by solution treatment and aging due to a large amount of transformedβand finer grain boundaryαand secondaryαat the expense of slight decrease of elongation and the ultimate strength, yield strength, elongation, reduction of area were 1100 MPa, 1030 MPa, 13%and 53%separately. A good combination of strength and ductility has been obtained by duplex annealing with the above values 940 MPa, 887.5 MPa, 15%and 51%respectively. Analysis between microstructure parameters and tensile properties showed that with the volume fraction of transformedβphase and the prior-βgrain size increasing, the ultimate strength, yield strength and reduction of area increased, but the elongation decreased. While the width of grain boundary α and secondary α showed a contrary effect on the tensile properties. Elimination of grain boundaryαas well as small prior-βgrain size can also improve ductility.
文摘The effects of strength mis-matching on J-integral and failure assessment line (FAL) of electron beam welded thick TC4-DT titanium alloy joints have been investigated.Elastic and elastic-plastic finite elements (FE) calculations on centre crack tensile (CCT) specimens were made,and the condition of 20% strength mis-matching was considered.The results indicate that the limit load of the joint can be substituted by that of the base metal.The error of substitution is less than 5%.The failure assessment lines for both over-matching and under-matching joints are increasingly close to that of the base metal,with the ratio of weld width to specimen width (H/W) decreasing.Moreover,the failure assessment lines of the joints can be devised using the stress-strain curves of the base metal,which will be convenient for the practical application of engineering
文摘以TC4-DT钛合金为研究对象,研究不同温度(20,300,500℃)对TC4-DT的摩擦磨损性能的影响。采用HT-500型摩擦磨损试验机对TC4-DT合金进行摩擦磨损实验,分析温度对摩擦因数及磨损率的影响;通过扫描电镜(Scanning electron microscope,SEM)和能谱(Energy dispersive spectrometer,EDS)等方法探究磨痕的形貌和成分变化及磨损机理。结果表明,随着温度的升高,磨损过程中TC4-DT合金表面不断生成氧化膜,摩擦因数从0.493下降到0.298,磨痕不断变窄变浅,磨损率大大降低;磨损机理在20℃时以粘着磨损、磨粒磨损为主,伴随着疲劳磨损;在300,500℃时以剥层磨损和氧化磨损为主,伴随少量的粘着磨损和磨粒磨损。
基金Projects (51101096, 51002093) supported by the National Natural Science Foundation of ChinaProject (1052nm05000) supported by Special Foundation of the Shanghai Science and Technology Commission for Nano-Materials ResearchProject (J51042) supported by Leading Academic Discipline Project of the Shanghai Education Commission, China
文摘A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding. The phase component, microstructure, composition distribution and properties of the composite layer were investigated. The composite layer has graded microstructures and compositions, due to the fast melting followed by rapid solidification and cooling during laser cladding. The TiC powders are completely dissolved into the melted layer during melting and segregated as fine dendrites when solidified. The size of TiC dendrites decreases with increasing depth. Y2O3 fine particles distribute in the whole clad layer. The Y2O3 particle enhanced Ni/TiC composite layer has a quite uniform hardness along depth with a maximum value of HV1380, which is 4 times higher than the initial hardness. The wear resistance of the Ti alloy is significantly improved after laser cladding due to the high hardness of the composite coating.
文摘研究了双重退火热处理对经不同的拉伸条件变形后的TC4-DT钛合金组织的影响。结果表明:双重退火后得到的组织与拉伸变形条件和第一重退火温度有关。当经最佳的应变速率5.6×10-4s-1和变形温度920~980℃变形后,随第一次退火温度升高,显微组织中次生α相析出量增加;在980℃变形后,经过双重退火后的合金组织可以得到编织紧密的网篮组织,且第一重退火温度在β单相区时得到的网篮组织的针状α相更加细长。当经最佳的变形温度940℃和不同的应变速率5.6×10-2~5.6×10-4s-1变形后,经过930℃/1 h AC+540℃/4 h AC双重退火的组织可以得到双态组织,而经过980℃/1 h AC+540℃/4 h AC双重退火的组织为魏氏组织。
