The light weight heat treated B-grade bulletproof steel was developed through composition design and optimization based on multiplex alloying,multiplex micro-alloying design ideas and complex phase structure strengthe...The light weight heat treated B-grade bulletproof steel was developed through composition design and optimization based on multiplex alloying,multiplex micro-alloying design ideas and complex phase structure strengthening theory.The puzzle how to avoid the quenching deformation problem of super high strength thin sheet was solved through heat treatment in a die with a set of cooling system.Such B-grade bulletproof steel plate has fine tempered lath martensite structure.The shooting and certification test results showed that the shoot resistance of B-grade bulletproof steel plate can meet the protection demand of Protection specification for cash carrying vehicles(GA 164—2005).In comparison with B-grade bulletproof steel plate made by one of the companies in Sweden,the weight of the developed B-grade bulletproof steel plate can be decreased by 8 %under the same shoot resistance condition.It will be meaningful for cash truck and anti-hijacking vehicle to realize light weight,energy conservation and emission reduction.展开更多
The bogie made of Grade B+ steel is one of the most important parts of heavy haul trains. Some accidents were found to be the result of fracture failure of the bogies. It is very important to find the reason why the f...The bogie made of Grade B+ steel is one of the most important parts of heavy haul trains. Some accidents were found to be the result of fracture failure of the bogies. It is very important to find the reason why the fracture failure occurred. Because Al was added for the final deoxidation during the smelting process of the Grade B+Steel, residual Al existed to some extent in the castings. High residual Al content in the bogie casting was presumed to be the reason for the fracture. In this work, the influence of residual Al content in the range of 0.015wt.% to 0.3wt.% on the microstructure and mechanical properties of the Grade B+ Steel was studied. The experimental results showed that when the residual Al content is between 0.02wt.% and 0.20wt.%, the mechanical properties of the steel meet the requirements of technical specification for heavy haul train parts, and the fracture is typical plastic fractures. If the residual Al content is less than 0.02wt.%, the microstructures are coarse, and the mechanical properties can not meet the demand of bogie steel castings. When the residual Al content is more than 0.2wt.%, the elongation, reduction of area, and low-temperature impact energy markedly deteriorate. The fracture mode then changes from plastic fracture to cleavage brittle fracture. Therefore, the amount of Al addition for the final deoxidation during the smelting process must be strictly controlled. The optimum addition amount needs to be controlled within the range of 0.02wt.% to 0.20wt.% for the Grade B+Steel.展开更多
In this paper,the high speed tension experiments have been performed on ultra high strength bulletproof steel.The specimen were cut from B-grade bulletproof steel sheet after hard-module quenching with thickness of 2....In this paper,the high speed tension experiments have been performed on ultra high strength bulletproof steel.The specimen were cut from B-grade bulletproof steel sheet after hard-module quenching with thickness of 2.3 mm.The mechanical properties at strain rates of 0.001 s-1,0.01 s-1,0.1 s-1and 1 s-1were carried out on MTS810,while those at higher strain rates of 200 s-1,500 s-1and 1 000 s-1were tested on HTM5020 high speed tension tester and Hopkinson bar.The data from the high speed tension experiments were fitted via Johnson-Cook constitutive equation,and the fracture surface of each specimen was analyzed by scanning electron microscope(SEM).The results indicate that,the shoot resistance capability of bulletproof steel is closely related to its strength,thickness and flow behaviors under high strain rate.The shoot resistance will be improved in the case of higher strength and better matching between strength and elongation.The Johnson-Cook constitutive equation fitted via experimental data provides fundament to numerical simulation.With the increase of strain rate,the size and depth of dimple trend to decrease and the depth of dimple changes less in steel with lower strength and higher elongation.The SEM analysis of fracture aspect is of benefit for further understanding of deformation and fracture mode under high strain rate.展开更多
文摘The light weight heat treated B-grade bulletproof steel was developed through composition design and optimization based on multiplex alloying,multiplex micro-alloying design ideas and complex phase structure strengthening theory.The puzzle how to avoid the quenching deformation problem of super high strength thin sheet was solved through heat treatment in a die with a set of cooling system.Such B-grade bulletproof steel plate has fine tempered lath martensite structure.The shooting and certification test results showed that the shoot resistance of B-grade bulletproof steel plate can meet the protection demand of Protection specification for cash carrying vehicles(GA 164—2005).In comparison with B-grade bulletproof steel plate made by one of the companies in Sweden,the weight of the developed B-grade bulletproof steel plate can be decreased by 8 %under the same shoot resistance condition.It will be meaningful for cash truck and anti-hijacking vehicle to realize light weight,energy conservation and emission reduction.
基金financially supported by the Heilongjiang Province Natural Science Foundation(QC2010110)
文摘The bogie made of Grade B+ steel is one of the most important parts of heavy haul trains. Some accidents were found to be the result of fracture failure of the bogies. It is very important to find the reason why the fracture failure occurred. Because Al was added for the final deoxidation during the smelting process of the Grade B+Steel, residual Al existed to some extent in the castings. High residual Al content in the bogie casting was presumed to be the reason for the fracture. In this work, the influence of residual Al content in the range of 0.015wt.% to 0.3wt.% on the microstructure and mechanical properties of the Grade B+ Steel was studied. The experimental results showed that when the residual Al content is between 0.02wt.% and 0.20wt.%, the mechanical properties of the steel meet the requirements of technical specification for heavy haul train parts, and the fracture is typical plastic fractures. If the residual Al content is less than 0.02wt.%, the microstructures are coarse, and the mechanical properties can not meet the demand of bogie steel castings. When the residual Al content is more than 0.2wt.%, the elongation, reduction of area, and low-temperature impact energy markedly deteriorate. The fracture mode then changes from plastic fracture to cleavage brittle fracture. Therefore, the amount of Al addition for the final deoxidation during the smelting process must be strictly controlled. The optimum addition amount needs to be controlled within the range of 0.02wt.% to 0.20wt.% for the Grade B+Steel.
文摘In this paper,the high speed tension experiments have been performed on ultra high strength bulletproof steel.The specimen were cut from B-grade bulletproof steel sheet after hard-module quenching with thickness of 2.3 mm.The mechanical properties at strain rates of 0.001 s-1,0.01 s-1,0.1 s-1and 1 s-1were carried out on MTS810,while those at higher strain rates of 200 s-1,500 s-1and 1 000 s-1were tested on HTM5020 high speed tension tester and Hopkinson bar.The data from the high speed tension experiments were fitted via Johnson-Cook constitutive equation,and the fracture surface of each specimen was analyzed by scanning electron microscope(SEM).The results indicate that,the shoot resistance capability of bulletproof steel is closely related to its strength,thickness and flow behaviors under high strain rate.The shoot resistance will be improved in the case of higher strength and better matching between strength and elongation.The Johnson-Cook constitutive equation fitted via experimental data provides fundament to numerical simulation.With the increase of strain rate,the size and depth of dimple trend to decrease and the depth of dimple changes less in steel with lower strength and higher elongation.The SEM analysis of fracture aspect is of benefit for further understanding of deformation and fracture mode under high strain rate.
