Deformation-Induced Grain-Interior α Precipitation and β Texture Evolution during the β-Processed Forging of a Near-β Titanium Alloy

• Published in: Metals (Basel ) Vol. 11; no. 9; p. 1405
• Main Authors: Kitashima, Tomonori, Meng, Lingjian, Watanabe, Makoto
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.09.2021
• Subjects: Cooling; Crack propagation; Deformation; Electron backscatter diffraction; Evolution; Forging; Forgings; Grain boundaries; hot forging; Microstructure; phase transformation; Scanning electron microscopy; Slip; slip system; Texture; titanium alloy; Titanium alloys; Titanium base alloys
• ISSN: 2075-4701; 2075-4701
• DOI: 10.3390/met11091405

The effect of grain-interior α precipitation on the β texture evolution of the near-β Ti-6246 alloy during through-transus forging was investigated in two-step sequential forgings. The microstructure and texture were analyzed using scanning electron microscopy, electron-backscatter diffraction, and X-ray diffraction. The previous β forging was performed at 1253 K at 0.01/s, while the subsequent forging in the (α + β) region was conducted at 1073 K at 0.01/s. The forging in the β region facilitated the penetration of the interior α phase into β grains and reduced the formation of grain boundary α. The {001} texture intensity increased during the forging in the single β region. By contrast, the increase in the {001} texture intensity was moderate at a lower temperature (1073 K) because the Schmid factor (SF) value of the {110} slip system drastically decreased, but those of the {112} and {123} slip systems increased before α precipitation. During α precipitation for all β forging ratios, the {110} slip system was activated, resulting in a lowering of the {001} texture intensity. The lower the forging temperature before interior α precipitation under a constant total forging ratio, the more the {001} texture intensity was suppressed in the final β texture, accompanied by interior α precipitation.