In this paper new high-strength and high-plasticity twinning induced plasticity （TWlP） steel for modern automobile body was investigated. Some basic experimental results were given. The results indicate the TWlP ste...In this paper new high-strength and high-plasticity twinning induced plasticity （TWlP） steel for modern automobile body was investigated. Some basic experimental results were given. The results indicate the TWlP steel has excellent properties. It exhibits high ultimate tensile strength （600,--1100 MPa） and extremely large elongation of 60% to 90%.In the future it would be capable of satisfying the requirements of new generation of vehicle.展开更多
The weldability of twin-induced plasticity(TWIP)steel with ultra-high strength via friction stir welding(FSW)technique was investigated,and microstructural evolution and deformation behavior of whole and micro-zones o...The weldability of twin-induced plasticity(TWIP)steel with ultra-high strength via friction stir welding(FSW)technique was investigated,and microstructural evolution and deformation behavior of whole and micro-zones of FSW TWIP joint were studied for the first time.The results showed that the content of recrystallized grains in the stir zone(SZ)increased from 10.5%of basal material(BM)to 14.2%,and that of heat affected zone(HAZ)increased to 78.6%.The percentage of annealing twins decreased from 26.8%in BM to 11%in SZ,while increased to 35%in HAZ.Compared with the BM,the ultimate tensile strength and yield strength of the FSW joint increased to 1036 and 550 MPa,respectively,reaching 106.7%and 110.9%of BM,respectively.The elongation of the entire joint was 50.5%,which was lower than that of BM due to the nonuniform deformation during the tensile test.The engineering strain was mainly concentrated in BM and SZ and transferred to each other during the tensile test,while the engineering strain in HAZ was always the lowest.Finally,the tensile fracture occurred in the SZ.The order of ultimate tensile strength of micro-zones in the FSW joint was as follows:HAZ>BM≈SZ.The order of yield strength was as follows:HAZ>BM>SZ.展开更多
The restoration mechanism of twin-induced plasticity(TWIP)steel during friction stir welding(FSW)changed with the degree of the deformation,and the microstructure evolution and dynamic recrystallization are complex an...The restoration mechanism of twin-induced plasticity(TWIP)steel during friction stir welding(FSW)changed with the degree of the deformation,and the microstructure evolution and dynamic recrystallization are complex and unclear.In this paper,the electron backscattered diffraction and transmission electron microscopy techniques were used to evaluate the dynamic grain structure of FSW joint of TWIP steel.The results showed that the dynamic recrystallization mechanisms in TWIP steel during FSW contained discontinuous dynamic recrystallization(DDRX)and continuous dynamic recrystallization(CDRX).The recrystallization mechanism transitioned from DDRX at the initial deformation stage to DDRX and CDRX at the middle deformation stage,eventually becoming primarily CDRX at the end deformation stage.Numerous annealing twin boundaries(ATBs)were formed within the joint,and the straight ATBs primarily resulted from grain growth accidents,while cluster-shaped ATBs were formed through re-excitations and decomposition of specific grain boundaries.展开更多
The influence of cold rolling reduction on microstructure and mechanical properties of the TWIP （ttwinning induced plasticity） steel was investigated. The results＇ indicated that the steel had better comprehensive ...The influence of cold rolling reduction on microstructure and mechanical properties of the TWIP （ttwinning induced plasticity） steel was investigated. The results＇ indicated that the steel had better comprehensive mechanical properties when cold rolling reduction was about 65.0% and the annealing temperature was 1000℃. The tensile strength of the steel is about 640MPa and the yield strength is higher than 255MPa, while the elongation is＇ above 82%. The microstructure is composed of austenitic matrix and annealing twins at room temperature, at the same time, a significant amount of annealing twins and stacking faults＇ are observed by transmission electron microscopy （TEM）. Mechanical twins play a dominant role during deformation, and result in exceUent mechanical properties.展开更多
The microstructure and crack behaviour of twinning induced plasticity （TWIP） steel during tensile deformation was investigated with in-situ scanning electron microscopy （SEM）. The results show that there are two m...The microstructure and crack behaviour of twinning induced plasticity （TWIP） steel during tensile deformation was investigated with in-situ scanning electron microscopy （SEM）. The results show that there are two modes of plastic deformation during tensile test in the Fe-Mn-C TWIP steel： dislocation gliding and deformation twins. During the process of tensile deformation, secondary deformed twins are found. Inclusions have played a role in the course of ductile fracture, and microcracks initiate from inclusions and twin-twin intersections.展开更多
The hot-deformation behavior of Fe-Mn-C twinning induced plasticity （TWIP） steel was investigated by conducting hot compression tests within a recommended hot rolling temperature range at various strain rates. Flow ...The hot-deformation behavior of Fe-Mn-C twinning induced plasticity （TWIP） steel was investigated by conducting hot compression tests within a recommended hot rolling temperature range at various strain rates. Flow resistance curves during hot-deformation were obtained, and strain rate sensitivities and activation energies for plastic deformation were calculated using the power law. It is found that the addition of Al and Si clearly increases the peak stresses for the present alloys, especially at 950℃. But Mn has a minor effect on the stress-strain curves and activation energy when its content varies from 15 mass% to 22 mass% for the present alloys.展开更多
文摘In this paper new high-strength and high-plasticity twinning induced plasticity （TWlP） steel for modern automobile body was investigated. Some basic experimental results were given. The results indicate the TWlP steel has excellent properties. It exhibits high ultimate tensile strength （600,--1100 MPa） and extremely large elongation of 60% to 90%.In the future it would be capable of satisfying the requirements of new generation of vehicle.
基金the National Natural Science Foundation of China(Nos.52034005,52227807,52104383,and 51974220)China’s National Defense Science and Technology(173 Program)(No.2021-JCJQ-JJ-0190)+2 种基金the Shaanxi Province National Science Fund for Distinguished Young Schol-ars(No.2022JC-24)the Key Research and Development Pro-gram of Shaanxi Province(No.2020ZDLGY13-06)the Scientific Re-search Program for Youth Innovation Team Construction of Shaanxi Provincial Department of Education(No.21JP058)。
文摘The weldability of twin-induced plasticity(TWIP)steel with ultra-high strength via friction stir welding(FSW)technique was investigated,and microstructural evolution and deformation behavior of whole and micro-zones of FSW TWIP joint were studied for the first time.The results showed that the content of recrystallized grains in the stir zone(SZ)increased from 10.5%of basal material(BM)to 14.2%,and that of heat affected zone(HAZ)increased to 78.6%.The percentage of annealing twins decreased from 26.8%in BM to 11%in SZ,while increased to 35%in HAZ.Compared with the BM,the ultimate tensile strength and yield strength of the FSW joint increased to 1036 and 550 MPa,respectively,reaching 106.7%and 110.9%of BM,respectively.The elongation of the entire joint was 50.5%,which was lower than that of BM due to the nonuniform deformation during the tensile test.The engineering strain was mainly concentrated in BM and SZ and transferred to each other during the tensile test,while the engineering strain in HAZ was always the lowest.Finally,the tensile fracture occurred in the SZ.The order of ultimate tensile strength of micro-zones in the FSW joint was as follows:HAZ>BM≈SZ.The order of yield strength was as follows:HAZ>BM>SZ.
基金supported by the National Natural Science Foundation of China(Nos.52034005,52227807,52104383,and 52222410)the Shaanxi Province National Science Fund for Distinguished Young Scholars(2022JC-24)+1 种基金the Key Research and Development Program of Shaanxi Province(2020ZDLGY13-06 and 2022JBGS2-01)the Scientific Research Program for Youth Innovation Team Construction of Shaanxi Provincial Department of Education(No.21JP058).
文摘The restoration mechanism of twin-induced plasticity(TWIP)steel during friction stir welding(FSW)changed with the degree of the deformation,and the microstructure evolution and dynamic recrystallization are complex and unclear.In this paper,the electron backscattered diffraction and transmission electron microscopy techniques were used to evaluate the dynamic grain structure of FSW joint of TWIP steel.The results showed that the dynamic recrystallization mechanisms in TWIP steel during FSW contained discontinuous dynamic recrystallization(DDRX)and continuous dynamic recrystallization(CDRX).The recrystallization mechanism transitioned from DDRX at the initial deformation stage to DDRX and CDRX at the middle deformation stage,eventually becoming primarily CDRX at the end deformation stage.Numerous annealing twin boundaries(ATBs)were formed within the joint,and the straight ATBs primarily resulted from grain growth accidents,while cluster-shaped ATBs were formed through re-excitations and decomposition of specific grain boundaries.
基金the National Natural Science Foundation of China （No. 50575022） Specialized Research Foundation for the Doctoral Program of Higher Education （No. 20040008024）.
文摘The influence of cold rolling reduction on microstructure and mechanical properties of the TWIP （ttwinning induced plasticity） steel was investigated. The results＇ indicated that the steel had better comprehensive mechanical properties when cold rolling reduction was about 65.0% and the annealing temperature was 1000℃. The tensile strength of the steel is about 640MPa and the yield strength is higher than 255MPa, while the elongation is＇ above 82%. The microstructure is composed of austenitic matrix and annealing twins at room temperature, at the same time, a significant amount of annealing twins and stacking faults＇ are observed by transmission electron microscopy （TEM）. Mechanical twins play a dominant role during deformation, and result in exceUent mechanical properties.
基金supported by the National High-Tech Research and Development Program of China (No.2008AA03E502)the Science and Technology Support Program of China (No.2006BAE03A06)
文摘The microstructure and crack behaviour of twinning induced plasticity （TWIP） steel during tensile deformation was investigated with in-situ scanning electron microscopy （SEM）. The results show that there are two modes of plastic deformation during tensile test in the Fe-Mn-C TWIP steel： dislocation gliding and deformation twins. During the process of tensile deformation, secondary deformed twins are found. Inclusions have played a role in the course of ductile fracture, and microcracks initiate from inclusions and twin-twin intersections.
文摘The hot-deformation behavior of Fe-Mn-C twinning induced plasticity （TWIP） steel was investigated by conducting hot compression tests within a recommended hot rolling temperature range at various strain rates. Flow resistance curves during hot-deformation were obtained, and strain rate sensitivities and activation energies for plastic deformation were calculated using the power law. It is found that the addition of Al and Si clearly increases the peak stresses for the present alloys, especially at 950℃. But Mn has a minor effect on the stress-strain curves and activation energy when its content varies from 15 mass% to 22 mass% for the present alloys.
