Microstructure evolution during warm working of Ti-5Al-5Mo-5V-1Cr-1Fe at 600 and 800 °C

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:563

Article

Zherebtsov, S. V.¹  Murzinova, M. A.²  Klimova, M. V.¹  Salishchev, G. A.¹  Popov, A. A.³  Semiatin, S. L.⁴ 

[1] Belgorod State Univ, Lab Bulk Nanostruct Mat, Belgorod 308015, Russia

[2] Inst Met Superplast Problems, Ufa 450001, Russia

[3] Ural Fed Univ, Ekaterinburg 620002, Russia

[4] USAF, Res Lab, Mat & Mfg Directorate, AFRL RXLM, Wright Patterson AFB, OH 45433 USA

关键词: Titanium alloys;    Thermomechanical processing;    Microstructure refinement;    Speroidization;    Precipitation;   

DOI  :  10.1016/j.msea.2012.11.042

来源: Elsevier

【 摘 要 】

Microstructure evolution during compression to the true height strain 0.29, 0.69, or 1.2 at 600 and 800 C of the beta-rich titanium alloy Ti-5Al-5Mo-5V-1Cr-1Fe (VT22) with an initial lamellar microstructure was established using scanning and transmission electron microscopy. It was found that microstructure evolution at both temperatures was controlled primarily by substructure evolution within the beta phase. At 800 degrees C, extensive recovery within the beta phase resulted in the formation of a stable structure comprising subgrains similar to 1.5 mu m in diameter. During deformation at this temperature, lamellae of the alpha phase fragmented via a boundary-grooving mechanism. Due to the sluggish diffusion kinetics, however, spheroidization at 800 degrees C was incomplete. At the lower processing temperature, recovery processes within the beta phase were much slower, leading to greater refinement of the beta matrix. The decomposition of the metastable beta phase during warm working, gave rise to very fine alpha-lath precipitates, which resulted in the formation of an ultrafine microstructure with a grain size of 0.5 mu m. (c) 2012 Elsevier B.V. All rights reserved.

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