Effect of low temperature thermo-mechanical treatment on microstructures and mechanical properties of TC4 alloy

Abstract

The effects of low temperature thermo-mechanical treatment (LTTMT) on microstructures and mechanical properties of Ti-6Al-4V (TC4) alloy were studied by optical microscopy (OM), tensile test, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The experimental results confirm that the strength of TC4 alloy can be improved obviously by LTTMT processing, which combines strain strengthening with aging strengthening. The effect of LTTMT on the alloy depends on the microstructure of the refined and dispersed α+β phase on the basis of high dislocation density by pre-deformation below recrystallization temperature. The tensile strength decreases with the increase of pre-deformation reduction. The optimal processing parameters of LTTMT for TC4 alloy are as follows: solution treatment at 900 °C for 15 min, pre-deformation in the range of 600–700°C with a reduction of 35%, finally aging at 540 °C for 4 h followed by air-cooling.

Keywords

Ti-6Al-4V (TC4) alloy / low temperature thermo-mechanical treatment / microstructure / mechanical properties / strain strengthening

References

[1] ZhangX.-y., ZhaoY.-q., BaiC.-guang.Titanium alloy and its application [M], 2005, Beijing, Chemical Industry Press: 287-305

[2] HanW.-b., ZhangK.-f., WangG.-feng.. Superplastic forming and diffusion bonding for honeycomb structure of Ti-6Al-4V alloy [J]. Journal of Materials Processing Technology, 2007, 183(2/3): 450-454

[3] LeeH. S., YoonJ. H., ChanH. P., YoungG. K., DongH. S., LeeC. S.. A study on diffusion bonding of superplastic Ti-6Al-4V ELI grade [J]. Journal of Materials Processing Technology, 2007, 187/188: 526-529

[4] LuC., ZhangL.-wen.. Numerical simulation on forging process of TC4 alloy mounting parts [J]. Transactions of Nonferrous Metals Society of China, 2006, 16(6): 1386-1390

[5] HyukjaeL., ShankarM.. Stress relaxation behavior of shot-peened Ti-6Al-4V under fretting fatigue at elevated temperature [J]. Materials Science and Engineering A, 2004, 366(2): 412-420

[6] LiuY., YangD.-z., WuW.-l., YangS.-qin.. Dry sliding wear behavior of Ti-6Al-4V alloy in air [J]. Journal of Harbin Institute of Technology: English Letter, 2002, 9(1): 67-71

[7] LiuY., YangD. Z., HeS. Y., WuW. L.. Microstructure developed in the surface layer of Ti-6Al-4V alloy after sliding wear in vacuum [J]. Materials Characterization, 2003, 50(4/5): 275-279

[8] BiswasA., DuttaM. J.. Surface characterization and mechanical property evaluation of thermally oxidized Ti-6Al-4V [J]. Materials Characterization, 2009, 60(6): 513-518

[9] NieL., LiF.-g., FangY.. New constitution relationship for TC4 alloy [J]. Aeronautical Materials Transaction, 2001, 21(3): 13-18

[10] LiL. X., PengD. S.. Development of constitute equations for Ti-6Al-4V alloy under hot-working condition [J]. Acta Metallurgica Sinica: English Letter, 2000, 13(1): 263-269

[11] ShademanS., SobovejoW. O.. An investigation of short fatigue crack growth in Ti-6Al-4V with colony microstructures [J]. Materials Science and Engineering A, 2002, 335(1/2): 116-127

[12] SinhaV., MercerC., SoboyejoW. O.. An investigation of short and long fatigue crack growth behavior of Ti-6Al-4V [J]. Material Science and Engineering A, 2000, 287(1): 30-42

[13] LuoL.-s., SuY.-q., GuoJ.-j., FuH.-zhi.. Formation of titanium hydride in Ti-6Al-4V alloy [J]. Journal of Alloys and Compounds, 2006, 425(1/2): 140-144

[14] HuangH.. Effect of high temperature thermo-mechanical treatment (HTTMT) on the structure and properties of TC4 alloy [J]. Optic and Precision Engineering, 1996, 4(4): 48-52

[15] KubiakK., SieniawskiJ.. Development of the microstructure and fatigue strength of two phase titanium alloys in the processes of forging and heat treatment [J]. Journal of Materials Processing Technology, 1998, 78(1/3): 117-121

[16] CuiN.-xian.Fracture analysis of metals [M], 1998, Harbin, Harbin Institute of Technology Press: 34-45