To clarify the high temperature flow stress behavior and microstructures evolution of a V-5Cr-5Ti （mass fraction, %） alloy, the isothermal hot compression tests were conducted in the temperature range of 1423-1573 K...To clarify the high temperature flow stress behavior and microstructures evolution of a V-5Cr-5Ti （mass fraction, %） alloy, the isothermal hot compression tests were conducted in the temperature range of 1423-1573 K with strain rates of 0.01, 0.1, and 1 s-1. The results show that the measured flow stress should be revised by friction and the calculated values of friction coefficient m are in the range of 0.45-0.56. Arrhenius-type constitutive equation was developed by regression analysis. The comparison between the experimental and predicted flow stress shows that the R~ and the average absolute relative error （AARE） are 0.948 and 5.44%, respectively. The measured apparent activation energy Qa is in the range of 540-890 kJ/mol. Both dis-continuous dynamic recrystallization （DDRX） and continuous dynamic recrystallization （CDRX） mechanisms are observed in the deformed alloy, but dynamic recovery （DRV） is the dominant softening mechanism up to a true strain of 1.5.展开更多
在Gleeble-1500热模拟机上对Ti-5Al-5Mo-5V-1Cr-1Fe合金进行高温热压缩实验,研究该合金在变形温度为750~900℃、应变速率为0.001~1 s 1条件下的流变应力行为。利用光学显微镜分析合金在不同变形条件下的组织演化规律。结果表明：合金的...在Gleeble-1500热模拟机上对Ti-5Al-5Mo-5V-1Cr-1Fe合金进行高温热压缩实验,研究该合金在变形温度为750~900℃、应变速率为0.001~1 s 1条件下的流变应力行为。利用光学显微镜分析合金在不同变形条件下的组织演化规律。结果表明：合金的流变应力随着应变速率的增大和变形温度的降低而增大;流变应力随着应变的增加而增大,出现峰值后逐渐趋于平稳;变形过程中的流变应力可用Arrhenius双曲正弦本构关系来描述,平均变形激活能为454.2 kJ/mol;各种变形条件均可细化原始晶粒尺寸。随着温度的升高和应变速率的降低,合金的主要软化机制由动态回复逐渐变为动态再结晶;在（α＋β）相区变形（750~850℃）时,α相对β晶粒的动态再结晶的发生起到阻碍作用。展开更多
采用热模拟试验机对Ti-5Al-5Mo-5V-1Cr-1Fe合金进行等温压缩试验,获得变形温度为750~900℃和应变速率为0.001~1 s 1时的真应力真应变曲线,并运用修正后的试验数据建立真应变为0.7的热加工图。通过显微组织观察,分析合金的变形机理,确定...采用热模拟试验机对Ti-5Al-5Mo-5V-1Cr-1Fe合金进行等温压缩试验,获得变形温度为750~900℃和应变速率为0.001~1 s 1时的真应力真应变曲线,并运用修正后的试验数据建立真应变为0.7的热加工图。通过显微组织观察,分析合金的变形机理,确定热变形失稳区。研究结果表明：Ti-5Al-5Mo-5V-1Cr-1Fe合金加工温度范围较宽,当加工温度低于800℃且变形速率大于0.1 s 1时易发生绝热剪切,造成流变失稳;随着变形温度升高,功率耗散因子η有增大趋势,合金的流动软化机制由动态回复逐渐变为动态再结晶,显微组织也随之细化、均匀。展开更多
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
基金Project(11105127) supported by the National Natural Science Foundation of China
文摘To clarify the high temperature flow stress behavior and microstructures evolution of a V-5Cr-5Ti （mass fraction, %） alloy, the isothermal hot compression tests were conducted in the temperature range of 1423-1573 K with strain rates of 0.01, 0.1, and 1 s-1. The results show that the measured flow stress should be revised by friction and the calculated values of friction coefficient m are in the range of 0.45-0.56. Arrhenius-type constitutive equation was developed by regression analysis. The comparison between the experimental and predicted flow stress shows that the R~ and the average absolute relative error （AARE） are 0.948 and 5.44%, respectively. The measured apparent activation energy Qa is in the range of 540-890 kJ/mol. Both dis-continuous dynamic recrystallization （DDRX） and continuous dynamic recrystallization （CDRX） mechanisms are observed in the deformed alloy, but dynamic recovery （DRV） is the dominant softening mechanism up to a true strain of 1.5.
文摘在Gleeble-1500热模拟机上对Ti-5Al-5Mo-5V-1Cr-1Fe合金进行高温热压缩实验,研究该合金在变形温度为750~900℃、应变速率为0.001~1 s 1条件下的流变应力行为。利用光学显微镜分析合金在不同变形条件下的组织演化规律。结果表明：合金的流变应力随着应变速率的增大和变形温度的降低而增大;流变应力随着应变的增加而增大,出现峰值后逐渐趋于平稳;变形过程中的流变应力可用Arrhenius双曲正弦本构关系来描述,平均变形激活能为454.2 kJ/mol;各种变形条件均可细化原始晶粒尺寸。随着温度的升高和应变速率的降低,合金的主要软化机制由动态回复逐渐变为动态再结晶;在（α＋β）相区变形（750~850℃）时,α相对β晶粒的动态再结晶的发生起到阻碍作用。
文摘采用热模拟试验机对Ti-5Al-5Mo-5V-1Cr-1Fe合金进行等温压缩试验,获得变形温度为750~900℃和应变速率为0.001~1 s 1时的真应力真应变曲线,并运用修正后的试验数据建立真应变为0.7的热加工图。通过显微组织观察,分析合金的变形机理,确定热变形失稳区。研究结果表明：Ti-5Al-5Mo-5V-1Cr-1Fe合金加工温度范围较宽,当加工温度低于800℃且变形速率大于0.1 s 1时易发生绝热剪切,造成流变失稳;随着变形温度升高,功率耗散因子η有增大趋势,合金的流动软化机制由动态回复逐渐变为动态再结晶,显微组织也随之细化、均匀。
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.
