Effect of Trace B Addition on Hot Workability and High-Cycle Fatigue Property of Ti-6A1-4V Alloy
Two types of heat treatment were applied to minor boron (B)-added Ti-6A1-4V. One was the beta anneal (BA) treatment,in which alloys were slowly cooled from the single beta-phase region,and the other was the recrystallization anneal (RA) treatment,in which alloys were forged in the (alpha+beta) two-phase region and subsequently annealed in the same twophase region. Ti-6A1-4V alloys showed typical colony micro-structures when they were subjected to the BA treatment. The alloy with 0. 1 wt. ％ B showed a refined colony microstructure compared to the B-free counterpart,due to the remarkable refinement of prior beta grain size. Both B-free and B-added alloys subjected to the same RA treatment exhibited an equiaxed microstructure with an equiaxed alpha grain size of about 5 μm. Hot workability of BA-treated B-added alloy was greatly improved. For example, the temperature limit within which alloys can deform homogeneously lowered about 300K under the compressive strain rate of 10° s-1. Both BA- and RAtreated B-modified alloys showed superior high-cycle fatigue (HCF) strength under the stress ratio of 0. 1 in the whole cycle range examined compared to B-free counterparts. For example,HCF strength at 10 cycles for RA-treated alloy increased from 650 MPa to 750 MPa in maximum stress by the addition of 0. 1 wt. ％ E. The fatigue crack initiated neither from TiB nor from the TiB/matrix interface but rather from the matrix itself. Thus it was confirmed that the minor addition of B is effective in increasing the hot workability and HCF strength of Ti-6A1-4V.
Titanium alloy boron addition grain refinement hot workability highrcycle fatigue
T. Kitaura M. Hagiwara O. Kano Y. Ono T. Yuri T. Ogata
Kyushu Institute of Technology ,2-4 Hibikino,Wakamatsu-ku ,Kitakyushu808-0196,Japart Toho Titanium Co. ,Ltd. , 3-3-5 Chigasaki ,Chigasaki City ,Kanagawa 253-8510, Japan National Institute for Materials Science, 1-2-1 Sengen,Tsukuba,Ibaraki 305-0047 Japan
国际会议
The 12th World Conference Titanium(第十二届世界钛会 Ti-2011)
北京
英文
1021-1024
2011-06-19（万方平台首次上网日期，不代表论文的发表时间）