Microstructure and Texture Variations in High Temperature Titanium Alloy Ti65 Sheets with Different Rolling Modes and Heat Treatments

Abstract

Ti65 alloy (Ti-5.8Al-4.0Sn-3.5Zr-0.5Mo-0.4Si-0.3Nb-1.0Ta-0.8W-0.05C) is the newly developed high temperature titanium alloy optimized from Ti60 alloys. The long-term service temperature of the alloy is as high as 650 °C, which is unattainable with the previous high temperature titanium alloy. It has excellent strength and excellent creep resistance, and has great application prospects in the aerospace industry. In the current study, the evolution of microstructure and texture of Ti65 alloy sheets developed by unidirectional rolling (UDR) and cross rolling (CR) followed by solution and aging treatment was investigated. The microstructure of the UDR sample consists of equiaxed α p , lamellar α s and few elongated α p , and the texture is the combination of minor B-type and major T-type texture, with the main component of basal {0001} fiber texture and { 01 1 ¯ 0 } < 2 1 ¯ 1 ¯ 0 > , respectively. Due to more active slip system resulted by transformed direction, the microstructure of the CR sample consists of more elongated α p , and the { 01 1 ¯ 0 } <0001> texture characterized as R-type texture forms in addition to B/T-type texture. With aging temperature increasing, the microstructures for both transform to duplex microstructure, and the thicknesses of lamellar α s increase. B-type texture becomes stronger, while T/R-type texture are weakened, which is caused by the combination of recrystallization, spheroidization, and variant selection. An abnormal increasing of T/R-type texture but constant B-type texture happens in the CR-600 sample, which is related to high recrystallization fraction. It is expected that the research results can provide useful references for the rolling of high temperature titanium alloy sheets and the precise control of microstructure/texture.

Dynamic Softening and Hardening Behavior and the Micro-Mechanism of a TC31 High Temperature Titanium Alloy Sheet within Hot Deformation

“…The proportion of MAGBs increased gradually when the strain was less than 0.5 and decreased gradually when the strain was greater than 0.5. Dynamic recrystallization mechanisms include continuous dynamic recrystallization (CDRX) characterized by the rotation of the subgrain boundary and discontinuous dynamic recrystallization (DDRX) characterized by the nucleation and growth of grains with small sizes [ 40 , 43 , 44 ]. The MAGBs is the transitional stage of evolution from LAGBs to HAGBs; therefore, the variation of MAGBs is closely related to the types of recrystallization [ 20 , 39 ].…”

Grain structure orientational change in Ti6Al4V alloys induced by sea water quenching and novel stress relief annealing process

“…For example, on the microstructure of Hot Rolled Ti-6Al-6Nb Alloy, reduction of elastic modulus to 106 GPA for medical application was realised [16]. The quenching process improves mechanical properties and alters materials microstructure [17][18][19][20][21]. The final desired microstructure with induced properties is dependent on the cooling rates and post heat treatment as to release the quenching stresses.…”

Effect of ‘Q’ Ratio on Texture Evolution of Ti-3Al-2.5V Alloy Tube during Rolling

“…In recent years, the evolution of the texture of hexagonal metals has been extensively studied, and the effect of deformation and heat treatment on the texture has been deeply revealed [2][3][4][5][6]. The preferred orientation of grains usually follows a specific crystallographic direction and is closely related to the stress direction in the deformation.…”