Terminal ballistic tests using 7.62 mm armor-piercing incendiary （API） projectiles were performed to evaluate the resistance to penetration of Ti-5Al-5Mo-5V-3Cr-IZr （Ti-55531） alloy. The dynamic properties were de...Terminal ballistic tests using 7.62 mm armor-piercing incendiary （API） projectiles were performed to evaluate the resistance to penetration of Ti-5Al-5Mo-5V-3Cr-IZr （Ti-55531） alloy. The dynamic properties were determined by a split Hopkinson pressure bar （SHPB） test system. Ti-55531 plates were subjected to two kinds of heat treatments, leading to the formation of high-strength and high-toughness plates. The results of SHPB test exhibit that the maximum impact absorbed energy of the high-strength plate at a strain rate of 2200 s^-1 is 270 MJ/m^3; however, the maximum value for the high-toughness plate at a strain rate of 4900 s^-1 is 710 MJ/m^3. The ballistic limit velocities for the high-strength and high-toughness plates with dimensions of 300 mm×300 mm×8 mm are 330 and 390 m/s, respectively. Excellent dynamic properties of Ti-55531 alloy correspond to good resistance to penetration. The microstructure evolution related to various impact velocities are observed to investigate the failure mechanism.展开更多
The dynamic fracture behaviors of Ti-6Al-4V alloy at high strain rate loading were investigated systemically through Taylor impact test, over the range of impact velocities from 145 m/s to 306 m/s. The critical impact...The dynamic fracture behaviors of Ti-6Al-4V alloy at high strain rate loading were investigated systemically through Taylor impact test, over the range of impact velocities from 145 m/s to 306 m/s. The critical impact velocity of fracture ranges from 217 m/s to 236 m/s. Smooth surfaces and ductile dimple areas were observed on the fracture surfaces. As the impact velocity reached 260 m/s, the serious melting regions were also observed on the fracture surfaces. Self-organization of cracks emerges when the impact velocity reaches 260 m/s, while some special cracks whose ＂tips＂ are not sharp but arc and smooth, and without any evidence of deformation or adiabatic shear band were also observed on the impact end surfaces. Examination of the sections of these special cracks reveals that the cracks expand along the two maximum shear stress directions respectively, and finally intersect as a tridimensional ＂stagger ridge＂ structure.展开更多
Ballistic behaviour of different zones of post-weld heat-treated(PWHT)magnesium alloy(AZ31B)target against 7.62 mm×39 mm armour-piercing(AP)projectile with a striking velocity of(430±20)m/s was determined.Ma...Ballistic behaviour of different zones of post-weld heat-treated(PWHT)magnesium alloy(AZ31B)target against 7.62 mm×39 mm armour-piercing(AP)projectile with a striking velocity of(430±20)m/s was determined.Magnesium alloy(AZ31B)welded joints were prepared by using friction stir welding(FSW)process and subjected to different heat treatment conditions.The microhardness values of non-heat-treated and heat-treated FSW joints were investigated.The results indicated that PWHT process(250°C,1 h)has improved the microhardness of heat-treated FSW joints.Scanning electron microscope(SEM)microstructure showed that heat treatment has caused the formation of fineα-Mg grains and tiny precipitates and made the dissolution ofβ-Mg17Al12 phase into the Mg matrix.The ballistic behaviour of PWHT zones was estimated by measuring the depth of penetration(DOP)of the projectile.Lower DOP value was observed for the base metal zone(BMZ)of a heat-treated welded joint.Post ballistic SEM examinations on the cross-section of all three zones of crater region showed the formation of adiabatic shear band(ASB).展开更多
基金Project(2012 DFG51540)supported by the Ministry of Science and Technology of China
文摘Terminal ballistic tests using 7.62 mm armor-piercing incendiary （API） projectiles were performed to evaluate the resistance to penetration of Ti-5Al-5Mo-5V-3Cr-IZr （Ti-55531） alloy. The dynamic properties were determined by a split Hopkinson pressure bar （SHPB） test system. Ti-55531 plates were subjected to two kinds of heat treatments, leading to the formation of high-strength and high-toughness plates. The results of SHPB test exhibit that the maximum impact absorbed energy of the high-strength plate at a strain rate of 2200 s^-1 is 270 MJ/m^3; however, the maximum value for the high-toughness plate at a strain rate of 4900 s^-1 is 710 MJ/m^3. The ballistic limit velocities for the high-strength and high-toughness plates with dimensions of 300 mm×300 mm×8 mm are 330 and 390 m/s, respectively. Excellent dynamic properties of Ti-55531 alloy correspond to good resistance to penetration. The microstructure evolution related to various impact velocities are observed to investigate the failure mechanism.
基金Project (51001014) supported by the Young Scientists Fund of the National Natural Science Foundation of China
文摘The dynamic fracture behaviors of Ti-6Al-4V alloy at high strain rate loading were investigated systemically through Taylor impact test, over the range of impact velocities from 145 m/s to 306 m/s. The critical impact velocity of fracture ranges from 217 m/s to 236 m/s. Smooth surfaces and ductile dimple areas were observed on the fracture surfaces. As the impact velocity reached 260 m/s, the serious melting regions were also observed on the fracture surfaces. Self-organization of cracks emerges when the impact velocity reaches 260 m/s, while some special cracks whose ＂tips＂ are not sharp but arc and smooth, and without any evidence of deformation or adiabatic shear band were also observed on the impact end surfaces. Examination of the sections of these special cracks reveals that the cracks expand along the two maximum shear stress directions respectively, and finally intersect as a tridimensional ＂stagger ridge＂ structure.
文摘Ballistic behaviour of different zones of post-weld heat-treated(PWHT)magnesium alloy(AZ31B)target against 7.62 mm×39 mm armour-piercing(AP)projectile with a striking velocity of(430±20)m/s was determined.Magnesium alloy(AZ31B)welded joints were prepared by using friction stir welding(FSW)process and subjected to different heat treatment conditions.The microhardness values of non-heat-treated and heat-treated FSW joints were investigated.The results indicated that PWHT process(250°C,1 h)has improved the microhardness of heat-treated FSW joints.Scanning electron microscope(SEM)microstructure showed that heat treatment has caused the formation of fineα-Mg grains and tiny precipitates and made the dissolution ofβ-Mg17Al12 phase into the Mg matrix.The ballistic behaviour of PWHT zones was estimated by measuring the depth of penetration(DOP)of the projectile.Lower DOP value was observed for the base metal zone(BMZ)of a heat-treated welded joint.Post ballistic SEM examinations on the cross-section of all three zones of crater region showed the formation of adiabatic shear band(ASB).
