摘要
Two types of 9Cr low activation martensitic steels （named 9Cr-1 and 9Cr-2） were developed in University of Science and Technology Beijing. 9Cr-1 and 9Cr-2 were produced by vacuum induction melting method, and examinations of the microstruc- tures were carried out with X-ray diffraction analysis, optical microscopy, scanning electron microscopy and transmission electron microscopy. The ultimate tensile strength and yield tensile strength were evaluated with tensile tests. The impact properties were characterized with Charpy impact experiments. The results indi- cated that 9Cr-1 and 9Cr-2 on as-received condition （95 ~C/30 min/water quenching plus 780 ~C/90 min/air cooling） were flflly martensitic steels free of ^-ferrite. The ul- timate tensile strength of 9Cr-1 and 9Cr-2 were 695 MPa and 680 MPa, respectively. However, 9Cr-2 showed a fine grain size of 4.8 pm, and its value of ductile-brittle transition temperature （DBTT） was -90 ~C under as-received condition. The additions of vanadium, titanium and boron accelerated the formation of MX precipitates and resulted in fine grains and precipitates. The fine grains effectively reduced the value of DBTT from -60 ℃ to -90 ℃ with identical upper shelf energy （USE）. The decrease in silicon concentration of 9Cr-2 induced a slight reduction in ultimate tensile strength from 695 MPa to 680 MPa.
Two types of 9Cr low activation martensitic steels （named 9Cr-1 and 9Cr-2） were developed in University of Science and Technology Beijing. 9Cr-1 and 9Cr-2 were produced by vacuum induction melting method, and examinations of the microstruc- tures were carried out with X-ray diffraction analysis, optical microscopy, scanning electron microscopy and transmission electron microscopy. The ultimate tensile strength and yield tensile strength were evaluated with tensile tests. The impact properties were characterized with Charpy impact experiments. The results indi- cated that 9Cr-1 and 9Cr-2 on as-received condition （95 ~C/30 min/water quenching plus 780 ~C/90 min/air cooling） were flflly martensitic steels free of ^-ferrite. The ul- timate tensile strength of 9Cr-1 and 9Cr-2 were 695 MPa and 680 MPa, respectively. However, 9Cr-2 showed a fine grain size of 4.8 pm, and its value of ductile-brittle transition temperature （DBTT） was -90 ~C under as-received condition. The additions of vanadium, titanium and boron accelerated the formation of MX precipitates and resulted in fine grains and precipitates. The fine grains effectively reduced the value of DBTT from -60 ℃ to -90 ℃ with identical upper shelf energy （USE）. The decrease in silicon concentration of 9Cr-2 induced a slight reduction in ultimate tensile strength from 695 MPa to 680 MPa.
基金
supported by National Basic Research Program of China(No.2007CB209800)
Chinese National Fusion Project for ITER(No.2010GB109000)
