K439B nickel-based superalloy is a new type of high-temperature material.There is insufficient research on its constitutive equations and numerical modeling of thermal stress.Isothermal tensile experiments of K439B su...K439B nickel-based superalloy is a new type of high-temperature material.There is insufficient research on its constitutive equations and numerical modeling of thermal stress.Isothermal tensile experiments of K439B superalloy at different temperatures(20°C-1,000°C)and strain rates(1.33×10^(-3)s^(-1)-5.33×10^(-3)s^(-1))were performed by using a Gleeble-3800 simulator.The elastic moduli at different temperatures(20°C-650°C)were measured by resonance method.Subsequently,stress-strain curves were measured for K439B superalloy under different conditions.The elastic-viscoplastic constitutive equations were established and the correspongding parameters were solved by employing the Perzyna model.The verification results indicate that the calculated values of the constitutive equations are in good agreement with the experimental values.On this basis,the influence of process parameters on thermal stress was investigated by numerical simulation and orthogonal experimental design.The results of orthogonal experimental design reveal that the cooling mode of casting has a significant influence on the thermal stress,while pouring temperature and preheating temperature of shell mold have minimal impact.The distribution of physical fields under optimal process parameters,determined based on the orthogonal experimental design results,was simulated.The simulation results determine separately the specific positions with maximum values for effective stress,plastic strain,and displacement within the casting.The maximum stress is about 1,000.0 MPa,the plastic strain is about 0.135,and the displacement is about 1.47 mm.Moreover,the distribution states of thermal stress,strain,and displacement are closely related to the distribution of the temperature gradient and cooling rate in the casting.The research would provide a theoretical reference for exploring the stress-strain behavior and numerical modeling of the effective stress of the alloy during the casting process.展开更多
The approximately equimolar ratio A1CrNiSiTi multi-principal element alloy （MPEA） coatings were fab- ricated by laser cladding on Ti-6Al-4V （Ti64） alloy. Scanning electron microscopy （SEM）, equipped with an ener...The approximately equimolar ratio A1CrNiSiTi multi-principal element alloy （MPEA） coatings were fab- ricated by laser cladding on Ti-6Al-4V （Ti64） alloy. Scanning electron microscopy （SEM）, equipped with an energy-dispersive spectroscopy （EDS）, and X-ray diffrac- tion （XRD） were used to characterize the microstructure and composition. Investigations show that the coatings consist of （Ti, Cr）5Si3 and NiA1 phases, formed by in situ reaction. The phase composition is initially explicated according to obtainable binary and ternary phase diagrams, and the formation Gibbs energy of TisSi3, VsSi3 and CrsSi3. Dry sliding reciprocating friction and wear tests of the A1CrNiSiTi coating and Ti64 alloy substrate without coating were evaluated. A surface mapping profiler was used to evaluate the wear volume. The worn surface was characterized by SEM-EDS. The hardness and wear resistance of the A1CrNiSiTi coating are well compared with that of the basal material （Ti64）. The main wear mechanism of the AICrNiSiTi coating is slightly adhesive transfer from GCrl5 counterpart, and a mixed layer com- posed of transferred materials and oxide is formed.展开更多
Advanced characterization techniques are utilized to investigate the effect of laser surface treatment on microstructural evolution of pure titanium（Ti）.The results show that there are three distinctly different typ...Advanced characterization techniques are utilized to investigate the effect of laser surface treatment on microstructural evolution of pure titanium（Ti）.The results show that there are three distinctly different types of microstructure from surface to substrate in Ti samples,including phase transformation and solidification microstructure in zone I（melting zone）;insufficient recrystallization grains with residual a martensitic plates in zone II（heat-affected zone,HAZ）;fully recrystallization microstructure in zone III（base metal,BM）.The hardness evolution profiles under different laser treatment parameters are similar.The highest hardness in MZ is ascribed to α plate,while the lowest hardness value in HAZ is due to the insufficiently recrystallized grains.The metallurgical process on the laser-modified Ti samples is systematically discussed in this work.展开更多
The interfacial reaction between aluminum melt and molten slag under an electric field plays a significant role in aluminum electro-slag refining. Here we studied this interracial reaction within 680 and 820 ℃ under ...The interfacial reaction between aluminum melt and molten slag under an electric field plays a significant role in aluminum electro-slag refining. Here we studied this interracial reaction within 680 and 820 ℃ under an electric field between 0 and 9 V. The evolution of aluminum composition was analyzed by inductively coupled plasma atomic emission spectroscopy. The dominant factor during the interfacial reaction was identified through orthogonal experiments, in which the slag-to-aluminum mass ratio, initial silicon concentration, electric voltage, reaction time, and temperature were selected as the influence factors. The greatest influence factor on the interracial reaction was found to be the reaction time. Also, single-factor experiments revealed that the reaction kinetic processes largely obeyed an irreversible kinetic model, and the silicon removal efficiency was enhanced by increasing the voltage and slag/metal ratio.展开更多
基金supported by the National Science and Technology Major Project of China(Grant No.J2019-VI-0004-0117)the State Key Laboratory of Special Rare Metal Materials(No.SKL2021K002)Northwest Rare Metal Materials Research Institute Ningxia Co.,Ltd.
文摘K439B nickel-based superalloy is a new type of high-temperature material.There is insufficient research on its constitutive equations and numerical modeling of thermal stress.Isothermal tensile experiments of K439B superalloy at different temperatures(20°C-1,000°C)and strain rates(1.33×10^(-3)s^(-1)-5.33×10^(-3)s^(-1))were performed by using a Gleeble-3800 simulator.The elastic moduli at different temperatures(20°C-650°C)were measured by resonance method.Subsequently,stress-strain curves were measured for K439B superalloy under different conditions.The elastic-viscoplastic constitutive equations were established and the correspongding parameters were solved by employing the Perzyna model.The verification results indicate that the calculated values of the constitutive equations are in good agreement with the experimental values.On this basis,the influence of process parameters on thermal stress was investigated by numerical simulation and orthogonal experimental design.The results of orthogonal experimental design reveal that the cooling mode of casting has a significant influence on the thermal stress,while pouring temperature and preheating temperature of shell mold have minimal impact.The distribution of physical fields under optimal process parameters,determined based on the orthogonal experimental design results,was simulated.The simulation results determine separately the specific positions with maximum values for effective stress,plastic strain,and displacement within the casting.The maximum stress is about 1,000.0 MPa,the plastic strain is about 0.135,and the displacement is about 1.47 mm.Moreover,the distribution states of thermal stress,strain,and displacement are closely related to the distribution of the temperature gradient and cooling rate in the casting.The research would provide a theoretical reference for exploring the stress-strain behavior and numerical modeling of the effective stress of the alloy during the casting process.
基金the National Natural Science Foundation of China(Nos.51871147,51821001)the Shanghai Aerospace Advanced Technology Joint Research Fund,China(No.USCAST2020-35).
基金supported by the Chongqing Research Program of Basic Research and Frontier Technology(No.CSTC2013jcyjA50016)the National Natural Science Foundation of China(Nos.51401039,51571037 and 51204110)the Scientific and Technological Research Program of Chongqing Municipal Education Commission(No.KJ1709204).
文摘The approximately equimolar ratio A1CrNiSiTi multi-principal element alloy （MPEA） coatings were fab- ricated by laser cladding on Ti-6Al-4V （Ti64） alloy. Scanning electron microscopy （SEM）, equipped with an energy-dispersive spectroscopy （EDS）, and X-ray diffrac- tion （XRD） were used to characterize the microstructure and composition. Investigations show that the coatings consist of （Ti, Cr）5Si3 and NiA1 phases, formed by in situ reaction. The phase composition is initially explicated according to obtainable binary and ternary phase diagrams, and the formation Gibbs energy of TisSi3, VsSi3 and CrsSi3. Dry sliding reciprocating friction and wear tests of the A1CrNiSiTi coating and Ti64 alloy substrate without coating were evaluated. A surface mapping profiler was used to evaluate the wear volume. The worn surface was characterized by SEM-EDS. The hardness and wear resistance of the A1CrNiSiTi coating are well compared with that of the basal material （Ti64）. The main wear mechanism of the AICrNiSiTi coating is slightly adhesive transfer from GCrl5 counterpart, and a mixed layer com- posed of transferred materials and oxide is formed.
基金Project supported by the National Natural Science Foundation of China （Nos. 11202183 and 50671092）, the National Science ＆ Tech- nology Pillar Program during the Eleventh Five-Year Plan Period （No. 2009BAG12A09）, the National High Technology Research and Development Program （863） of China （No. 2011AAllA101）, and the Zhejiang Provincial Natural Science Foundation of China （No. Y4100193）
基金supported by the National Natural Science Foundation of China (Nos. 51401039 and 51501026)the Natural Science Foundation of Chongqing (No. CSTC2014jcyj A50017)the Scientific and Technological Research Program of Chongqing Municipal Education Commission (Nos. KJ1500923 and KJ1709204)
文摘Advanced characterization techniques are utilized to investigate the effect of laser surface treatment on microstructural evolution of pure titanium（Ti）.The results show that there are three distinctly different types of microstructure from surface to substrate in Ti samples,including phase transformation and solidification microstructure in zone I（melting zone）;insufficient recrystallization grains with residual a martensitic plates in zone II（heat-affected zone,HAZ）;fully recrystallization microstructure in zone III（base metal,BM）.The hardness evolution profiles under different laser treatment parameters are similar.The highest hardness in MZ is ascribed to α plate,while the lowest hardness value in HAZ is due to the insufficiently recrystallized grains.The metallurgical process on the laser-modified Ti samples is systematically discussed in this work.
基金supported by National Natural Science Foundation of China (Grant Nos. 51274141,51204110)National Basic Research Program of China (Grant No. 2012CB619505)Science and Technology Commission of Shanghai Municipality (STCSM) for high-tech project (Grant Nos. 15111108000)
文摘The interfacial reaction between aluminum melt and molten slag under an electric field plays a significant role in aluminum electro-slag refining. Here we studied this interracial reaction within 680 and 820 ℃ under an electric field between 0 and 9 V. The evolution of aluminum composition was analyzed by inductively coupled plasma atomic emission spectroscopy. The dominant factor during the interfacial reaction was identified through orthogonal experiments, in which the slag-to-aluminum mass ratio, initial silicon concentration, electric voltage, reaction time, and temperature were selected as the influence factors. The greatest influence factor on the interracial reaction was found to be the reaction time. Also, single-factor experiments revealed that the reaction kinetic processes largely obeyed an irreversible kinetic model, and the silicon removal efficiency was enhanced by increasing the voltage and slag/metal ratio.
