Mechanism of α lamellae spheroidization and strengthening plasticization of TC21 titanium alloy after post forging heat treatment

doi:10.13251/j.issn.0254-6051.2023.08.022

Abstract

Abstract: TC21 titanium alloy was subjected to spheroidization heat treatment after multi-directional forging under optimal parameters(920 ℃-0.92 single pass true strain-3 cycles-water cooling), and the tensile properties of the specimens before and after forging and after spheroidization heat treatment were tested. The evolution law of α lamellae spheroidization (equiaxation) under different heat treatment parameters (temperature of 830-920 ℃, holding time of 1-4 h) of the alloy was studied and the strengthening plasticization mechanism of the alloy was revealed. The results show that after optimal multi-directional forging, the preferred subsequent spheroidizing heat treatment parameters for the TC21 titanium alloy are 890 ℃-2 h-air cooling, which can promote α lamellae spheroidization, and make that the yield strength and elongation of the TC21 titanium alloy are significantly improved, reaching 894.0 MPa and 13.2%, respectively. The strengthening plasticization mechanism of the TC21 titanium alloy after spheroidization heat treatment is mainly fine grain strengthening caused by α phase grain refinement and dislocation strengthening induced by needle-like secondary α phase in β phase.

Key words: TC21 titanium alloy, multi-directional forging, spheroidization heat treatment, α lamellae spheroidization, strengthening plasticization mechanism

CLC Number:

TG166.5

Tao Cheng, Cui Xia, Ouyang Delai, Lan Xixin, Wan Xingcai. Mechanism of α lamellae spheroidization and strengthening plasticization of TC21 titanium alloy after post forging heat treatment[J]. Heat Treatment of Metals, 2023, 48(8): 138-143.

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