研究了近α型钛合金TG6经α+β两相区热加工的盘锻件在600℃长时暴露过程中的显微组织演变及其对热稳定性的影响.结果表明:经600℃/100h和600℃/300h长时高温暴露后,TG6钛合金的室温拉伸强度略有提高,其增幅在5%左右,而其拉伸塑性显著降低,塑性保持率小于50%,拉伸断口趋于平直化,且存在梯田状台阶和二次裂纹等,表现为显著的解理断裂特征.在600℃高温长时暴露过程中,TG6钛合金中的显微组织变化主要有在基体组织中的共格有序α_2相析出及硅化物析出.随着高温暴露时间的延长,TG6钛合金的显微组织逐渐趋于稳定,拉伸性能的变化也相应趋缓.α_2相析出促进了拉伸变形时位错滑移的平面化及变形不均匀,是热稳定性下降的主要原因;而硅化物析出协同促进位错滑移集中化,是热稳定性下降的次要因素.
Microstructural evolution of a near-α titanium alloy TG6 disc forging processed in α+β phase field during long-term high temperature exposure and its influence on the thermal stability were studied. The results show that the room temperature tensile strength increased about 5% and the ductility reduced remarkably lower than 50% after 600℃/100h or 300h exposed for TG6 titanium alloy, and the fracture surface has a tendency of flat, terrace-like steps and secondary crack which showed an obvious cleavage fracture characteristic. During long-term exposure under 600℃ environment, the microstructural change is precipitation of the coherent ordered α_2 phase and silicide. The microstructure and the tensile properties tend to be stable with increasing the exposure time. The precipitation of α_2 phase is the main reason for the great loss of ductility during high temperature long-term exposure because the precipitated α_2 may promote planar slip and inhomogeneous deformation while tensile deformation. The precipitation of silicide may promote the intensity of slip and is the minor reason for the ductility loss.
参考文献
| [1] | James C. Williams;Edgar A. Starke Jr. .Progress in structural materials for aerospace systems[J].Acta materialia,2003(19):5775-5799. |
| [2] | WINSTONE M R;PARTRIDGE A;BROOKS J W.The contribution of advanced high temperature materials to future aeroengine[A].,2001:63-73. |
| [3] | NEAL D F.Development of TIMETAL834[A].TMS,2001:199-213. |
| [4] | BANIA P J.An advanced alloy for elevated temperature[J].Journal of Metals March,1988:20-22. |
| [5] | MOISEYEV Valentin N.Titanium Alloys Russian Aircraft and Aerospace Applications[M].CRC Press,Inc,2006:145-147. |
| [6] | Williams JC .Alternate materials choices--some challenges to the increased use of Ti alloys[J].Materials Science & Engineering, A. Structural Materials: Properties, Misrostructure and Processing,1999(2):107-111. |
| [7] | Albrecht J .Comparing fatigue behavior of titanium and nickel-based alloys[J].Materials Science & Engineering, A. Structural Materials: Properties, Misrostructure and Processing,1999(2):176-186. |
| [8] | DIETMAR Helm.Application of high temperature titanium alloys in aero-engine--Limits due to bulk and surface related properties[A].TMS,2006:3-12. |
| [9] | JONES C D.Surface and substrate stability of titanium alloys used in aerospace applications[A].,2001:219-227. |
| [10] | ROSENBERG H W.Titanium alloying in theory and practice[A].Pergamon Press,Oxford,UK,1970:851-859. |
| [11] | LüTJERING G;WILLIAMS J C.Titanium[M].Springer-verlag,2003:17-44. |
| [12] | KOLACHEV B A;ILYIN A A;VOLODIN V A.About the purposefulness of comparison of titanium alloys in terms of aluminum and molybdenum equivalents[A].Sant Petersberg,Russia,1999:53-60. |
| [13] | LüTJERING G;WEISSMANN S .Mechanical properties of age-hardened titanium-aluminum alloys[J].Acta Metallurgica,1970,18:785-795. |
| [14] | BLACKBURN M J .The ordering transformation in titanium:aluminum alloys containing up to 25 at.Pct aluminum[J].Trans of the Metal Society of AIME,1967,236:1200-1208. |
| [15] | ARDAKANI M G;SHOLLOCK B A;FLOWER H M.The effect of oxygen on microstructure of α and α_2 phase in titanium-rich Ti-Al alloys[A].:2242-2249. |
| [16] | RAMACHANDRA C;SINGH VAKIL .Silicide precipitation in alloy Ti-6Al-5Zr-0.5Mo-0.25Si[J].Metallurgical Transactions A,1982,13:771-775. |
| [17] | FLOWER H M;SWANN P R;WEST R F .Silicide precipitation in the Ti-Zr-Al-Si system[J].Metallurgical Transactions A,1971,2:3289-3297. |
| [18] | SINGH A K;ROY T;RAMACHANDRA C .Microstructural stability on aging of an α+β titanium alloy:Ti-6Al-1.6Zr-3.3Mo-0.30Si[J].Metallurgical and Materials Transactions A,1996,27:1167-1173. |
| [19] | Vikas Hasija;S. Ghosh;Michael J. Mills .Deformation and creep modeling in polycrystalline Ti-6Al alloys[J].Acta materialia,2003(15):4533-4549. |
| [20] | J.C. WILLIAMS;R.G. BAGGERLY;N.E. PATON .Deformation Behavior of HCP Ti-Al Alloy Single Crystals[J].Metallurgical and Materials Transactions, A. Physical Metallurgy and Materials Science,2002(3a):837-850. |
| [21] | J. R. Cho;D. Dye;K. T. Conlon;M. R. Daymond;R. C. Reed .Intergranular strain accumulation in a near-alpha titanium alloy during plastic deformation[J].Acta materialia,2002(19):4847-4864. |
| [22] | WOODFIELD A P;POSTANS P J;LORETTO M H et al.The effect of long-term high temperature exposure on the structure and properties of the titanium alloy Ti 5331S[J].Acta Metallurgica,1988,36:507-515. |
| [23] | BLACKBURN M J .Relationship of microstructure to some mechanical properties of Ti-8Al-1Mo-1V[J].Trans of the ASM,1966,59:694-708. |
| [24] | EVANS D J;BRODERICK T F;WOODHOUSE J B.On the synergism of α_2 and silicides in Ti-6Al-2Sn-2Cr-2Zr-2Mo-Si[A].:2413-2420. |
| [25] | SHAMBLEN C E .Embrittlement of titanium alloys by long time,high temperature expose[J].Metallurgical and Materials Transactions,1971,2:277-280. |
| [26] | MADSEN A;GHONEM H .Separating the effects of Ti3Al and silicide precipitates on the tensile and crack growth behavior at room temperature and 593℃ in a near-alpha titanium alloy[J].Journal of Materials Engineering and Performance,1995,4(03):301-307. |
| [27] | MADSEN A;GHONEM H .Effects of aging on the tensile and fatigue behavior of the near-α Ti-1100 at room temperature and 593℃[J].Materials Science and Engineering A:Structural Materials Properties Microstructure and Processing,1994,{?}:177,63-73. |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%