{11-22}compression twin plays an important role in accommodating deformation along the c axis of HCP metals.However,the studies on the interface structure of{11-22}twin boundary(TB),especially the twin tip,and the cor...{11-22}compression twin plays an important role in accommodating deformation along the c axis of HCP metals.However,the studies on the interface structure of{11-22}twin boundary(TB),especially the twin tip,and the corresponding local stress release mechanism are still limited.This work studied the interface characters of{11-22}TB of a deformed pure titanium by transmission electron microscope.The{11-22}TB presented serrated character,consisting of coherent twin boundary(CTB)and(0002)_(T)//(11-2-2)_(M)or(11-2-2)_(T)//(0002)_(M)steps,and the twin tip was fully composed of the basal-pyramidal(BPy)and pyramidal-basal(PyB)steps.The twin tip presents asymmetric morphology and the step height at the twin tip is much larger than that away from the twin tip.Two types of local stress accommodation mechanisms were observed:zonal dislocation emission and hexagonal close packed structure to facecentered cubic structure transformation.The zonal dislocation was produced by the dissociation of the1/3<11-2-3>dislocation that was nucleated at the twin tip and the phase transformation was introduced by emission of Shockley partial dislocations from the{11-22}twin boundary.展开更多
In view of two consecutive failures of Siemens 3RH1122-2KF40 relay on DKZ15 electric bus of Beijing metro line 10, it is found that Siemens 3RH1122-2KF40 relay has the defects of unreliable contact mechanical structur...In view of two consecutive failures of Siemens 3RH1122-2KF40 relay on DKZ15 electric bus of Beijing metro line 10, it is found that Siemens 3RH1122-2KF40 relay has the defects of unreliable contact mechanical structure and degraded contact electrical performance. In order to further improve the reliability of the key circuits of the train of line 10, eliminate the hidden dangers of vehicle faults, and reduce the failure rate and the cost of use and maintenance, it is decided to replace this type of relay. In the early stage of the transformation, the failure cause analysis, relay selection, comparative test and life accounting were carried out, and the transformation scheme was finally formed. The replacement relay effectively makes up for the deficiencies in the mechanical and electrical performance of Siemens 3RH1122-2KF40 relay, and is more in line with the actual needs of urban rail transit operation under the balanced repair mode in the future. At present, the transformation of DKZ15 electric buses of line 10 has been completed. After the transformation, the vehicle operation is in good condition, and the maximum operation mileage has exceeded 600000 km. Through relay transformation, the reliability of key circuits of the train is effectively improved, the maintenance and replacement free in the whole life cycle of the train are achieved, and the labor and material costs are reduced, which lays a solid quality guarantee for promoting the balanced maintenance mode of metro vehicles in the future.展开更多
基金supported by the National Natural Science Foundation of China(grant number 51828102)The Project of Innovation-driven Plan in Central South University(No.2019CX026)。
文摘{11-22}compression twin plays an important role in accommodating deformation along the c axis of HCP metals.However,the studies on the interface structure of{11-22}twin boundary(TB),especially the twin tip,and the corresponding local stress release mechanism are still limited.This work studied the interface characters of{11-22}TB of a deformed pure titanium by transmission electron microscope.The{11-22}TB presented serrated character,consisting of coherent twin boundary(CTB)and(0002)_(T)//(11-2-2)_(M)or(11-2-2)_(T)//(0002)_(M)steps,and the twin tip was fully composed of the basal-pyramidal(BPy)and pyramidal-basal(PyB)steps.The twin tip presents asymmetric morphology and the step height at the twin tip is much larger than that away from the twin tip.Two types of local stress accommodation mechanisms were observed:zonal dislocation emission and hexagonal close packed structure to facecentered cubic structure transformation.The zonal dislocation was produced by the dissociation of the1/3<11-2-3>dislocation that was nucleated at the twin tip and the phase transformation was introduced by emission of Shockley partial dislocations from the{11-22}twin boundary.
文摘In view of two consecutive failures of Siemens 3RH1122-2KF40 relay on DKZ15 electric bus of Beijing metro line 10, it is found that Siemens 3RH1122-2KF40 relay has the defects of unreliable contact mechanical structure and degraded contact electrical performance. In order to further improve the reliability of the key circuits of the train of line 10, eliminate the hidden dangers of vehicle faults, and reduce the failure rate and the cost of use and maintenance, it is decided to replace this type of relay. In the early stage of the transformation, the failure cause analysis, relay selection, comparative test and life accounting were carried out, and the transformation scheme was finally formed. The replacement relay effectively makes up for the deficiencies in the mechanical and electrical performance of Siemens 3RH1122-2KF40 relay, and is more in line with the actual needs of urban rail transit operation under the balanced repair mode in the future. At present, the transformation of DKZ15 electric buses of line 10 has been completed. After the transformation, the vehicle operation is in good condition, and the maximum operation mileage has exceeded 600000 km. Through relay transformation, the reliability of key circuits of the train is effectively improved, the maintenance and replacement free in the whole life cycle of the train are achieved, and the labor and material costs are reduced, which lays a solid quality guarantee for promoting the balanced maintenance mode of metro vehicles in the future.
