Effect of Oxygen Hardened Surface Layer on Fatigue Properties of Ti-5Al-2Fe-3Mo with Fine Acicular Microstructure
Fatigue properties of a high strength α+β titanium alloy Ti-5Al-2Fe-3Mo (Super-TIX?523AFM) having fine acicular microstructure are examined with specially emphasizing on influences of oxygen hardened surface layer to apply the alloy to intake engine valves for automobiles. Ti-5Al-2Fe-3Mo has superior fatigue strength to Ti-6Al-4V intrinsically. Because the a phase which precipitates in the β matrix during cooling after the β heat treatment is considerably fine including the grain boundary α,fatigue properties of the alloy with fine acicular microstructure are almost the same as those of both annealed and STAed (solution treated and aged) materials when the materials do not have oxygen hardened surface layer. Fatigue strength of Ti-5Al2Fe-3Mo drastically decreases by the oxygen hardened surface layer depending on the heat treatment conditions just like Ti-6Al4V. However, high fatigue strength can be achieved by optimizing the oxygen hardening heat treatment conditions by taking both thickness of the hardened layer and the characteristic of the matrix into account. Furthermore, FPB (fine particles bombardment or shot peening) treatment on the oxygen hardened surface layer improves fatigue strength to a level of that without surface hardened layer by an effect of residual compressive stress.
Titanium alloy oxygen hardened layer fatigue strength acicular microstructure shot-peening
Kenichi Mori Hideki Fujii Norimichi Fukaya Tadayoshi Tominaga
Steel Research Labs.,Nippon Steel Corporation,3434 Shimata,Hikari,Yamaguchi,743-8510,Japan Steel Research Labs.,Nippon Steel Corporation,20-1 Shintomi,Futtsu,Chiba,293-8511 Japan Aisan Industry Co. LTD.,1-1-1 Kyouwa,Obu,Aichi,474-8588 Japan
国际会议
The 12th World Conference Titanium(第十二届世界钛会 Ti-2011)
北京
英文
2232-2236
2011-06-19（万方平台首次上网日期，不代表论文的发表时间）