Reduced-activation ferritic/martensitic steels(RAFMs) such as CLF-1 steel, have been developed as candidate structural materials for breeding blanket in fusion reactors. Hot isostatic pressing(HIP) diffusion method is...Reduced-activation ferritic/martensitic steels(RAFMs) such as CLF-1 steel, have been developed as candidate structural materials for breeding blanket in fusion reactors. Hot isostatic pressing(HIP) diffusion method is expected to provide the most promising method to solve the problem to join cooling rectangular channels with thin panels during fabrication of the first wall in breeding blankets. Mechanical and microstructural characterization of HIPed joints of CLF-1 steel with four typical surface roughness has been investigated. The results indicate that with the increase of surface roughness, the tensile properties are similar to as-received CLF-1 steel, the elongation and the area reduction decreased, the impact energy decreased sharply. The HIPed joints are very sensitive to the bonding surface states, the roughness could influence degassing, oxide and cavities formation, diffusion efficiency of bonding surface, and reduce the roughness, efficient degassing and elimination of oxide formation of the HIP joint surfaces is important to obtain a satisfactory joint.展开更多
In the present work,the irradiation hardening behavior of a Chinese low-activation ferritic/martensitic steel CLF-1,a candidate for fusion reactor blankets,is studied.Specimens were irradiated with high-energy14N and5...In the present work,the irradiation hardening behavior of a Chinese low-activation ferritic/martensitic steel CLF-1,a candidate for fusion reactor blankets,is studied.Specimens were irradiated with high-energy14N and56Fe ions at the terminal of a cyclotron to three successively increasing damage levels of 0.05,0.1 and 0.2 displacements per atom(dpa)at about-50°C.The energy of the incident ions was dispersed to 11 successively decreasing grades using an energy degrader,thereby generating an atomic displacement damage plateau in the specimens from the surface to a depth of 25μm,which is sufficiently broad for the Vickers hardness test.Eight different loads(i.e.98 mN,196 m N,490 m N,980 m N,1.96 N,4.9 N,9.8 N and 19.6 N)were applied to the specimens to obtain the depth profiles of the Vickers hardness by using a microhardness tester.Hardening was observable at the lowest damage level,and increased with increasing irradiation dose.A power-law correlation of the Vickers hardness with the damage level(HV0=1.49+0.76 dpa0.31)is proposed.Testing with a nano-indentation technique was also performed,and a linear relationship between the Vickers micro-hardness and the nanohardness(HV0=0.83 H0)was observed.A comparison with other RAFM steels(CLAM,JLF-1,F82 H,EUROFER97 etc.)under neutron or charged particle irradiation conditions shows that most of the RAFM steels exhibit similar power-law exponents in the dose dependence of irradiation hardening.The difference in the irradiation hardening may be attributed to differences in microstructure prior to irradiation.展开更多
Cold metal transfer （CMT） welding of nickel-coated Q235 steel studs with 606l Al alloy was carried out using ER4043 as filler metal. The welding process was stable, and appearance of weld formed well without surface...Cold metal transfer （CMT） welding of nickel-coated Q235 steel studs with 606l Al alloy was carried out using ER4043 as filler metal. The welding process was stable, and appearance of weld formed well without surface defect under the parameters of welding current 121 A, welding voltage 15.4 V and welding speed 6 r/min. The microstructure of fiUer metal was analyzed by means of scanning electron microscopy. The filler metal and 6061 Al alloy were fused to form fusion welding interface, the fusion zone had a good bonding without any micro defect. The steel stud did not melt and brazing interface was formed between the filler metal and steel stud. Two different reaction layers existed in the brazing interface, the Fe2Al5 layer about 10 -12 p^m formed near the steel stud side, and the other layer was mainly composed of FeAl3. Nickel-rich zone was formed in the root toe area of the fillet weld, which was mainly composed of Al3Ni2. The tensile tests showed that the maximum shearing strength of the joints was 129 MPa. The joint was brittle fractured in the intermetallic compound layer where plenty of FeAl3 were distributed continuously.展开更多
The objective of this study was to investigate the influence of strengthening mechanisms on the high-temperature mechanical properties of China low-activation ferrite(CLF-1)steel,which underwent thermodynamic design a...The objective of this study was to investigate the influence of strengthening mechanisms on the high-temperature mechanical properties of China low-activation ferrite(CLF-1)steel,which underwent thermodynamic design and thermo-mechanical treatment(TMT).The microstructure characterization in the normalized and tempered condition and the TMT condition was carried out using optical microscopy,X-ray diffractometer,and scanning electron microscopy with electron backscatter diffraction.High-resolution transmission electron microscopy was employed to determine the crystallographic structures of precipitated phases.The results indicated that the addition of Ti led to an increase in the allocation of C in MC phase and an enhancement in the content of MC phase.Compared to CLF-P steel in the normalized and tempered condition,a 1.5-fold increase in dislocation density and an order of magnitude improvement in MX phase density were achieved after TMT.The formation of high-density nano-scale MC phases during TMT played a significant role in precipitation strengthening due to their favorable coherent relationship with the matrix and low interfacial free energy.The excellent high-temperature mechanical properties observed in CLF-P steel after TMT can be attributed to the combined effects of precipitation strengthening,dislocation strengthening,and lath strengthening.展开更多
基金supported by the National Key R&D Program of China with grant numbers 2017YFE0300601the open project of Beijing Engineering Researching Center of Laser Technology with grant numbers BG00462018-02。
文摘Reduced-activation ferritic/martensitic steels(RAFMs) such as CLF-1 steel, have been developed as candidate structural materials for breeding blanket in fusion reactors. Hot isostatic pressing(HIP) diffusion method is expected to provide the most promising method to solve the problem to join cooling rectangular channels with thin panels during fabrication of the first wall in breeding blankets. Mechanical and microstructural characterization of HIPed joints of CLF-1 steel with four typical surface roughness has been investigated. The results indicate that with the increase of surface roughness, the tensile properties are similar to as-received CLF-1 steel, the elongation and the area reduction decreased, the impact energy decreased sharply. The HIPed joints are very sensitive to the bonding surface states, the roughness could influence degassing, oxide and cavities formation, diffusion efficiency of bonding surface, and reduce the roughness, efficient degassing and elimination of oxide formation of the HIP joint surfaces is important to obtain a satisfactory joint.
基金sponsored by the National Magnetic Confinement Fusion Program(No.2011GB108003)National Natural Science Foundation of China(No.U1532262)。
文摘In the present work,the irradiation hardening behavior of a Chinese low-activation ferritic/martensitic steel CLF-1,a candidate for fusion reactor blankets,is studied.Specimens were irradiated with high-energy14N and56Fe ions at the terminal of a cyclotron to three successively increasing damage levels of 0.05,0.1 and 0.2 displacements per atom(dpa)at about-50°C.The energy of the incident ions was dispersed to 11 successively decreasing grades using an energy degrader,thereby generating an atomic displacement damage plateau in the specimens from the surface to a depth of 25μm,which is sufficiently broad for the Vickers hardness test.Eight different loads(i.e.98 mN,196 m N,490 m N,980 m N,1.96 N,4.9 N,9.8 N and 19.6 N)were applied to the specimens to obtain the depth profiles of the Vickers hardness by using a microhardness tester.Hardening was observable at the lowest damage level,and increased with increasing irradiation dose.A power-law correlation of the Vickers hardness with the damage level(HV0=1.49+0.76 dpa0.31)is proposed.Testing with a nano-indentation technique was also performed,and a linear relationship between the Vickers micro-hardness and the nanohardness(HV0=0.83 H0)was observed.A comparison with other RAFM steels(CLAM,JLF-1,F82 H,EUROFER97 etc.)under neutron or charged particle irradiation conditions shows that most of the RAFM steels exhibit similar power-law exponents in the dose dependence of irradiation hardening.The difference in the irradiation hardening may be attributed to differences in microstructure prior to irradiation.
基金supported by the Natural Science Foundation of Jiangsu Province(No.BK20131261)
文摘Cold metal transfer （CMT） welding of nickel-coated Q235 steel studs with 606l Al alloy was carried out using ER4043 as filler metal. The welding process was stable, and appearance of weld formed well without surface defect under the parameters of welding current 121 A, welding voltage 15.4 V and welding speed 6 r/min. The microstructure of fiUer metal was analyzed by means of scanning electron microscopy. The filler metal and 6061 Al alloy were fused to form fusion welding interface, the fusion zone had a good bonding without any micro defect. The steel stud did not melt and brazing interface was formed between the filler metal and steel stud. Two different reaction layers existed in the brazing interface, the Fe2Al5 layer about 10 -12 p^m formed near the steel stud side, and the other layer was mainly composed of FeAl3. Nickel-rich zone was formed in the root toe area of the fillet weld, which was mainly composed of Al3Ni2. The tensile tests showed that the maximum shearing strength of the joints was 129 MPa. The joint was brittle fractured in the intermetallic compound layer where plenty of FeAl3 were distributed continuously.
基金This work was supported by the State Key Laboratory of Nuclear Physics and Technology,Peking University(No.NPT2021KF-ZX).
文摘The objective of this study was to investigate the influence of strengthening mechanisms on the high-temperature mechanical properties of China low-activation ferrite(CLF-1)steel,which underwent thermodynamic design and thermo-mechanical treatment(TMT).The microstructure characterization in the normalized and tempered condition and the TMT condition was carried out using optical microscopy,X-ray diffractometer,and scanning electron microscopy with electron backscatter diffraction.High-resolution transmission electron microscopy was employed to determine the crystallographic structures of precipitated phases.The results indicated that the addition of Ti led to an increase in the allocation of C in MC phase and an enhancement in the content of MC phase.Compared to CLF-P steel in the normalized and tempered condition,a 1.5-fold increase in dislocation density and an order of magnitude improvement in MX phase density were achieved after TMT.The formation of high-density nano-scale MC phases during TMT played a significant role in precipitation strengthening due to their favorable coherent relationship with the matrix and low interfacial free energy.The excellent high-temperature mechanical properties observed in CLF-P steel after TMT can be attributed to the combined effects of precipitation strengthening,dislocation strengthening,and lath strengthening.
