摘要
对比研究了在780℃固溶+500℃时效(STA)和780℃热轧+780℃固溶+500℃时效(RSTA)两种工艺处理后得到的不同形态初生α_(p)相和次生α_(s)相对Ti55531合金力学性能的影响。结果表明:经过STA处理后的显微组织由等轴状的α_(p)相和含有细针状α_(s)相的β转变组织构成,具有良好的析出强化效果;经过RSTA处理后的显微组织由椭球状的α_(p)相和含有片层状α_(s)相的β转变组织构成,再结晶程度的提高同时带来了显著的细晶强化。STA试样的抗拉强度达到1523 MPa,而断裂总延伸率仅有2.99%,这是由于含有细针状α_(s)相的β转变组织承担塑性变形的能力较差,以及较软的等轴α_(p)相与硬的β转变组织变形协调性差导致的。而RSTA试样的抗拉强度为1483 MPa,断裂总延伸率为5.35%,这是由于片层状α_(s)相通过剪切和弯曲变形提高了β转变组织承担塑性变形的能力,同时经过位错强化的α_(p)相与β转变组织的变形协调性更好,进一步提高了塑性。因此,经过RSTA处理的样品具有更加优异的强塑性匹配。
Effects of morphologies of the primaryα_(p) phase and secondaryα_(s) phase on the mechanical properties of the Ti55531 alloy,obtained after two processes—solid solution treatment at 780℃followed by aging at 500℃(STA)and hot rolling at 780℃then followed by solid solution treatment at 780℃and aging at 500℃(RSTA)were investigated.The results show that the microstructure after the STA treatment consists of equiaxedα_(p) phase andβ-transformed microstructure containing fine,needle-likeα_(s) phase,exhibiting a strong precipitation strengthening effect.The microstructure after the RSTA treatment consists of ellipsoidalα_(p) phase andβ-transformed microstructure with lamellarα_(s) phase.The RSTA state specimens exhibit a higher degree of recrystallization,and the fine-grain strengthening effect resulting from recrystallization largely compensates for the lack of precipitation strengthening.For mechanical properties,the tensile strength of the STA state specimen achieves 1523 MPa with total extention of only 2.99%.This limited elongation is attributed to the poor ability of theβ-transformed microstructure containing fine needle-likeα_(s) phase to accommodate plastic deformation,as well as the inadequate coordination between the softer equiaxedα_(p) phase and the harderβ-transformed microstructure during deformation.Consequently,there is not a significant difference in strength between the two groups of specimens.The tensile strength of the RSTA state specimens is 1483 MPa,with an total extention of 5.35%.The lamellarα_(s) phase enhances the ability of theβ-transformed microstructure to accommodate plastic deformation through shear and bending mechanisms.Additionally,the improved deformation coordination between the dislocation-strengthenedα_(p) and theβ-transformed microstructure further increases the macroscopic plastic deformation capacity of the specimens.As a result,the RSTA state specimens own the superior strength-ductility synergy.
作者
刘斌华
李可尔
赵鹏程
陈威
Liu Binhua;Li Keer;Zhao Pengcheng;Chen Wei(State Key Laboratory for Mechanical Behavior of Materials,Xi'an Jiaotong University,Xi'an Shaanxi 710049,China;Shaanxi Tiancheng Aerospace Co.,Ltd.,Xianyang Shaanxi 712000,China)
出处
《金属热处理》
北大核心
2025年第9期76-85,共10页
Heat Treatment of Metals
基金
陕西省重点研发计划“揭榜挂帅”项目(2023JBGS-20)
咸阳市重大技术攻关项目(L2023-ZDKJ-JSGG-GY-008)。
关键词
钛合金
热轧
固溶
时效
组织性能
强塑化
titanium alloy
hot rolling
solution treatment
aging
microstructure and properties
strengthening and plasticizing
作者简介
刘斌华(2001-),女,硕士,主要研究方向为钛及钛合金,E-mail:liubinhua@stu.xjtu.edu.cn。;通信作者:陈威,副教授,博士,E-mail:weichen813@xjtu.edu.cn。
