摘要
采用电子束对新型耐650℃使用的高温钛合金板材进行焊接,并进行1 000℃/1 h/AC+700℃/4 h/AC的退火处理,研究了接头的组织、硬度分布,母材和接头的拉伸性能和持久性能.结果表明,接头组织由α相、少量β相、以及大量细小的再结晶α相构成.接头中母材、热影响区和焊缝的显微硬度值比较均匀,介于440～490HV之间.室温条件下,母材和接头的抗拉强度均高于1 000 MPa,延伸率均介于7%～10%; 650℃拉伸,母材抗拉强度达到了750 MPa,延伸率最高达20%;接头的抗拉强度在700 MPa以下,延伸率在10%～14%之间.接头与母材的持久断裂均是由孔洞聚集形成微裂纹,在力的作用下不断扩展,直至最终断裂.而接头中柱状晶的晶界促进了裂纹的扩展,所以母材的持久寿命和应变优于接头.根据结果分别得出了650℃下接头和母材应力与寿命的关系式.
The microstructure,microhardness,tensile property,and endurance property of a new high temperature titanium alloy Ti650 were studied after electron beam welding and heat treatment at 1 000 ℃/1 h/AC + 700 ℃/4 h/AC. The results indicated that the microstructure of the base metal( BM),heat affected zone( HAZ),and fusion zone( FZ) all included α phases,small amount β phases,and lots of fine recrystallized α phases. The corresponding microhardness of joints was relatively even in the range of 440 HV to 490 HV. At room temperature,the tensile strength and elongation of joints and BM were both higher than1 000 MPa and 7% ~10%. While at 650 ℃,those of BM were about 750 MPa and up to 20%,and those of joints were below 700 MPa and 10% ~ 14%. The endurance ruptures of joints and BM were both attributed to the aggregation of micro voids,and further extended under the stress until ultimate fracture. The difference between joints and BM was that the grain boundaries of the columnar crystals of joints promoted the propagation of crack. That’ s why the joint of Ti650 showed good endurance life compared with the BM and the results could be fitted to a prediction equation.
作者
李昌健
刘昕
雷永平
LI Changjian;LIU Xin;LEI Yongping(College of Material Science and Engineering,Beijing University of Technology,Beijing 100124,China;AVIC Beijing Aeronautical Manufacturing Technology Research Institute,Beijing 10024,China)
出处
《材料科学与工艺》
EI
CAS
CSCD
北大核心
2018年第6期16-22,共7页
Materials Science and Technology
关键词
高温钛合金
电子束焊接
组织
力学性能
持久性能
high temperature titanium alloy
electron beam welding
microstructure
mechanical properties
endurance property
