The effects of Ti-Mo-V composite addition on the evolution of precipitates in marine 10Ni5CrMoV steel andthe corresponding strength and toughness mechanisms were systematically investigated.Ti-Mo-V composite addition ...The effects of Ti-Mo-V composite addition on the evolution of precipitates in marine 10Ni5CrMoV steel andthe corresponding strength and toughness mechanisms were systematically investigated.Ti-Mo-V composite addition canform the Ti_(x)Mo_(y)V_(z)C carbide with TiC as core and Mo-V as shell in the order of Ti(C)→V→Mo.The yield strength of thespecimens is increased from 815 MPa to 876 MPa due to the nanoscale precipitates enhancing the pinning effect on grainboundaries and dislocations,and the contribution of precipitation and dislocation strengthening is increased.The decrease of ductile-brittle transition temperature from−103 to−116℃is attributed to the decrease in equivalent grainsize and the increase of high-angle grain boundary misorientation,which hinders the initiation and propagation of cracks.When the mass fraction of Ti is 0.05%,the strength and cryogenic toughness can be improved synergistically,which alsoprovides a theoretical basis and experimental reference for exploring the more excellent combination of strength andcryogenic toughness of marine 10Ni5CrMoV steel.展开更多
In order to improve the tribology behavior in aviation kerosene, molybdenum （Mo） modified layers were fabricated on Ti6Al4V base alloy using a double-glow plasma surface alloying technique. The morphology, microstru...In order to improve the tribology behavior in aviation kerosene, molybdenum （Mo） modified layers were fabricated on Ti6Al4V base alloy using a double-glow plasma surface alloying technique. The morphology, microstructure, microhardness and element depth distribution of the Mo modified layers were studied. The tribology properties of Ti6Al4V base alloy, Mo modified layers and 5CrMnMo tool steel sliding with GCr15 steel or QSn4-3 copper alloy counterparts in aviation kerosene were comparatively researched. The effect of roughness on the sliding wear behavior was discussed. The results indicate that the Mo modified layers with polishing treatments not only reduce the friction coefficient of Ti6Al4V base, but also enhance the wear resistance of the counterparts. The Mo modified layers have better tribology behavior than 5CrMnMo steel. It is also found that the wear volume loss of the counterparts is proportional to the value of roughness of Mo modified layers, which is related directly to the ploughing wear between micro convex bodies of the layers and counterparts.展开更多
Taking a Ti−5Al−5Mo−5V−1Cr−1Fe alloy as exemplary case,the fatigue crack growth sensitivity and fracture features with various tailoredαphase morphologies were thoroughly investigated using fatigue crack growth rate(...Taking a Ti−5Al−5Mo−5V−1Cr−1Fe alloy as exemplary case,the fatigue crack growth sensitivity and fracture features with various tailoredαphase morphologies were thoroughly investigated using fatigue crack growth rate(FCGR)test,optical microscopy(OM)and scanning electron microscopy(SEM).The tailored microstructures by heat treatments include the fine and coarse secondaryαphase,as well as the widmanstatten and basket weave features.The sample with coarse secondaryαphase exhibits better comprehensive properties of good crack propagation resistance(with long Paris regime ranging from 15 to 60 MPa·m1/2),high yield strength(1113 MPa)and ultimate strength(1150 MPa),and good elongation(11.6%).The good crack propagation resistance can be attributed to crack deflection,long secondary crack,and tortuous crack path induced by coarse secondaryαphase.展开更多
The microstructure characteristics in early stage shear localization of near-αTi−6Al−2Zr−1Mo−1V titanium alloy were investigated by split Hopkinson pressure bar(SHPB)tests using hat-shaped specimens.The microstructur...The microstructure characteristics in early stage shear localization of near-αTi−6Al−2Zr−1Mo−1V titanium alloy were investigated by split Hopkinson pressure bar(SHPB)tests using hat-shaped specimens.The microstructural evolution and deformation mechanisms of hat-shaped specimens were revealed by electron backscattered diffraction(EBSD)method.It is found that the nucleation and expansion of adiabatic shear band(ASB)are affected by both geometric and structural factors.The increase of dislocation density,structure fragment and temperature rise in the deformation-affected regions provide basic microstructural conditions.In addition to the dislocation slips,the extension twins detected in shear region also play a critical role in microstructural fragmentation due to twin-boundaries effect.Interestingly,the sandwich structure imposes a crucial influence on ASB,which finally becomes a mature wide ASB in the dynamic deformation.However,due to much larger width,the sandwich structure in the middle of shear region is also possible to serve as favorable nucleation sites for crack initiation.展开更多
To get a deep understanding of the evolution behavior of equiaxedαphase in Ti−8Al−1Mo−1V alloy during annealing,its static coarsening mechanism was studied based on the calculations of coarsening exponent n and the a...To get a deep understanding of the evolution behavior of equiaxedαphase in Ti−8Al−1Mo−1V alloy during annealing,its static coarsening mechanism was studied based on the calculations of coarsening exponent n and the activation energy forαboundary migration.The result of n=6 indicates a special coarsening mechanism of equiaxedαphase.The activation energy forαboundary migration is calculated to be 138 kJ/mol,which is close to the activation energy for grain growth of pureα-Ti.It is revealed that the coarsening of equiaxedαcan be mainly attributed to the self-diffusion of Ti atoms across theα/αboundaries.Based on the experimental findings,a static coarsening kinetics model of equiaxedαgrains in theα+βfield is established.At last,the effects of the coarsening behavior of equiaxedαon tensile properties were studied.展开更多
In order to prepare heatresistant inner layer of hot-forging die, plasma spraying, plasma re- melting and plasma spray welding were adopted. Cr3C2 coatings of Ni-Based were prepared respectively with 10%, 20% and 30% ...In order to prepare heatresistant inner layer of hot-forging die, plasma spraying, plasma re- melting and plasma spray welding were adopted. Cr3C2 coatings of Ni-Based were prepared respectively with 10%, 20% and 30% Cr3C2 powder and W6Mo5Cr4V2 substrate. The coating microstructure analysis, the micro-hardness test, and the measurement of thermal parameters of coating were conducted. The experimental results show that the coating has the better thermo-physical property by using plasma spray welding method with the powder ratio of 90% Ni60 and 10% Cr3C2, and by this way the micro-hardness of coating can achieve 1100 HV.展开更多
基金Project(2023YFE0200300)supported by the National Key K&D Program of ChinaProject(52174303,51874084)supported by the National Natural Science Foundation of ChinaProject(B21001)supported by the Introducing Talents of Discipline to Universities,China。
文摘The effects of Ti-Mo-V composite addition on the evolution of precipitates in marine 10Ni5CrMoV steel andthe corresponding strength and toughness mechanisms were systematically investigated.Ti-Mo-V composite addition canform the Ti_(x)Mo_(y)V_(z)C carbide with TiC as core and Mo-V as shell in the order of Ti(C)→V→Mo.The yield strength of thespecimens is increased from 815 MPa to 876 MPa due to the nanoscale precipitates enhancing the pinning effect on grainboundaries and dislocations,and the contribution of precipitation and dislocation strengthening is increased.The decrease of ductile-brittle transition temperature from−103 to−116℃is attributed to the decrease in equivalent grainsize and the increase of high-angle grain boundary misorientation,which hinders the initiation and propagation of cracks.When the mass fraction of Ti is 0.05%,the strength and cryogenic toughness can be improved synergistically,which alsoprovides a theoretical basis and experimental reference for exploring the more excellent combination of strength andcryogenic toughness of marine 10Ni5CrMoV steel.
基金Projects (50671085, 51171154) supported by the National Natural Science Foundation of ChinaProject (2007AA03Z521) supported by the High-tech Research and Development Program of China
文摘In order to improve the tribology behavior in aviation kerosene, molybdenum （Mo） modified layers were fabricated on Ti6Al4V base alloy using a double-glow plasma surface alloying technique. The morphology, microstructure, microhardness and element depth distribution of the Mo modified layers were studied. The tribology properties of Ti6Al4V base alloy, Mo modified layers and 5CrMnMo tool steel sliding with GCr15 steel or QSn4-3 copper alloy counterparts in aviation kerosene were comparatively researched. The effect of roughness on the sliding wear behavior was discussed. The results indicate that the Mo modified layers with polishing treatments not only reduce the friction coefficient of Ti6Al4V base, but also enhance the wear resistance of the counterparts. The Mo modified layers have better tribology behavior than 5CrMnMo steel. It is also found that the wear volume loss of the counterparts is proportional to the value of roughness of Mo modified layers, which is related directly to the ploughing wear between micro convex bodies of the layers and counterparts.
基金Project(U1867201)supported by the National Natural Science Foundation of ChinaProject supported by State Key Laboratory of Powder Metallurgy,Central South University,China。
文摘Taking a Ti−5Al−5Mo−5V−1Cr−1Fe alloy as exemplary case,the fatigue crack growth sensitivity and fracture features with various tailoredαphase morphologies were thoroughly investigated using fatigue crack growth rate(FCGR)test,optical microscopy(OM)and scanning electron microscopy(SEM).The tailored microstructures by heat treatments include the fine and coarse secondaryαphase,as well as the widmanstatten and basket weave features.The sample with coarse secondaryαphase exhibits better comprehensive properties of good crack propagation resistance(with long Paris regime ranging from 15 to 60 MPa·m1/2),high yield strength(1113 MPa)and ultimate strength(1150 MPa),and good elongation(11.6%).The good crack propagation resistance can be attributed to crack deflection,long secondary crack,and tortuous crack path induced by coarse secondaryαphase.
基金financial support from Pre-research Project of Equipment Development Department of China(No.41422010505)the Technology Innovation Leading Program of Shanxi Province,China(No.2019CGHJ-21)。
文摘The microstructure characteristics in early stage shear localization of near-αTi−6Al−2Zr−1Mo−1V titanium alloy were investigated by split Hopkinson pressure bar(SHPB)tests using hat-shaped specimens.The microstructural evolution and deformation mechanisms of hat-shaped specimens were revealed by electron backscattered diffraction(EBSD)method.It is found that the nucleation and expansion of adiabatic shear band(ASB)are affected by both geometric and structural factors.The increase of dislocation density,structure fragment and temperature rise in the deformation-affected regions provide basic microstructural conditions.In addition to the dislocation slips,the extension twins detected in shear region also play a critical role in microstructural fragmentation due to twin-boundaries effect.Interestingly,the sandwich structure imposes a crucial influence on ASB,which finally becomes a mature wide ASB in the dynamic deformation.However,due to much larger width,the sandwich structure in the middle of shear region is also possible to serve as favorable nucleation sites for crack initiation.
基金financial supports from the China Scholarship Council(No.201906935013)the National Natural Science Foundation of China(No.51801132).
文摘To get a deep understanding of the evolution behavior of equiaxedαphase in Ti−8Al−1Mo−1V alloy during annealing,its static coarsening mechanism was studied based on the calculations of coarsening exponent n and the activation energy forαboundary migration.The result of n=6 indicates a special coarsening mechanism of equiaxedαphase.The activation energy forαboundary migration is calculated to be 138 kJ/mol,which is close to the activation energy for grain growth of pureα-Ti.It is revealed that the coarsening of equiaxedαcan be mainly attributed to the self-diffusion of Ti atoms across theα/αboundaries.Based on the experimental findings,a static coarsening kinetics model of equiaxedαgrains in theα+βfield is established.At last,the effects of the coarsening behavior of equiaxedαon tensile properties were studied.
文摘In order to prepare heatresistant inner layer of hot-forging die, plasma spraying, plasma re- melting and plasma spray welding were adopted. Cr3C2 coatings of Ni-Based were prepared respectively with 10%, 20% and 30% Cr3C2 powder and W6Mo5Cr4V2 substrate. The coating microstructure analysis, the micro-hardness test, and the measurement of thermal parameters of coating were conducted. The experimental results show that the coating has the better thermo-physical property by using plasma spray welding method with the powder ratio of 90% Ni60 and 10% Cr3C2, and by this way the micro-hardness of coating can achieve 1100 HV.
