摘要
TC21合金具备较高的强度和断裂韧性,然而其拉伸和冲击韧性的内在控制机理差异还不明确。本实验通过调控固溶温度和冷却速率制备出不同显微组织,研究其拉伸和冲击性能。结果表明,拉伸和冲击韧性表现出不同的变化规律,塑性较好的双态组织的冲击韧性比塑性最差的全片层组织的冲击韧性低,说明拉伸性能和冲击韧性的内在控制机理有所不同,时效后的性能(时效后塑性无明显变化但冲击韧性显著下降)进一步证实了这一点。拉伸变形时,试样在发生颈缩前整个区域均发生塑性变形,双态组织中αp和βt之间发生的协调变形得以充分发挥,而全片层组织集束尺寸较大且其内部片层α取向一致,位错滑移长度较大,易发生塑性应变局域化,造成其强塑性匹配差于双态组织。冲击时,高应变速率作用下裂纹在缺口根部快速萌生和扩展,塑性变形集中在裂纹尖端附近小范围内,造成双态组织中αp和βt之间的协调变形不能充分发挥,而全片层组织的集束尺寸较大,导致集束界面对塑性变形的影响较小,此时片层α和β成为控制塑性变形的有效单元,粗片层α和β具有较好的塑性变形能力,造成其获得较高的萌生功,和拉伸表现出较差的塑性相悖,此外,大角度α集束界面造成裂纹偏转而形成曲折的路径,最终造成其冲击韧性高于双态组织。为获得拉伸性能和冲击韧性的良好匹配,可通过热处理调制出由含量较少的αp和内部形成粗大片层α和β的βt所构成的双态组织。
TC21 alloy has high strength and fracture toughness.However,the differences in the intrinsic control mechanisms of their tensile and impact toughness are not clarified.In this work,different microstructures were prepared by regulating the solid solution temperature and cooling rate to study the tensile and impact properties.The results show that tensile performance and impact toughness exhibit different variation laws.The impact toughness of the bimodal structure with better plasticity is lower than that of the full lamellar structure with the worst plasticity,indicating that the intrinsic control mechanisms of tensile properties and impact toughness are different,which is further confirmed by the post-aging properties(no significant change in plasticity but significant decrease in impact toughness after aging).During tensile deformation,plastic deformation occurs in the whole region of the specimen before necking occurs,and the coordination deformation betweenαp andβt in the bimodal structure is fully developed;while the full lamellar structure has a larger colony size,its internal lamellarαorientation is uniform,and the dislocation slip length is larger,making it susceptible to plastic strain localization,and resulting in a poorer strength plasticity matching than that of the bimodal structure.Under the influence of high strain rate,the crack initiation and propagation at the notch root are rapid,and the plastic deformation is concentrated in a small range near the crack tip,resulting in the fact that coordination deformation betweenαp andβt in bimodal structure cannot be fully played.By contrast,the largeαcolony size of the full lamellar structure leads to less influence of theαcolony interface on plastic deformation,and the lamellarαandβbecome an effective unit to control plastic deformation.The coarse lamellarαandβhave good plastic deformation ability,resulting in higher crack initiation energy,which is inconsistent with the poor plasticity during tension.In addition,the large angle interface ofα
作者
雷磊
朱琦玮
赵秦阳
赵永庆
Lei Lei;Zhu Qiwei;Zhao Qinyang;Zhao Yongqing(School of Physics and Optoelectronic Engineering,Yangtze University,Jingzhou 434023,China;School of Mechanical Engineering,Yangtze University,Jingzhou 434023,China;School of Materials Science and Engineering,Chang’an University,Xi’an 710064,China;Northwest Institute for Nonferrous Metal Research,Xi’an 710016,China)
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2024年第5期1449-1457,共9页
Rare Metal Materials and Engineering
基金
国家自然科学基金(52101122)
湖北省高等学校优秀中青年科技创新团队计划项目(T2020008)。
关键词
TC21钛合金
拉伸性能
冲击韧性
变形机制
裂纹扩展
TC21 titanium alloy
tensile property
impact toughness
deformation mechanism
crack propagation
