固溶处理对Ti-3.0Al-2.3Cr-1.3Fe钛合金组织与力学性能的影响

Influence of solution treatment on microstructure and mechanical properties of Ti-3.0Al-2.3Cr-1.3Fe titanium alloy

利用XRD、OM、SEM和TEM等技术研究固溶温度和冷却速度对Ti-3.0Al-2.3Cr-1.3Fe钛合金的显微组织及力学性能的影响。结果表明:该合金经过960℃固溶处理,水淬(WQ)后的组织主要由α′马氏体和β相组成,空冷(AC)后的组织主要由α相和残留β基体组成,炉冷(FC)后的组织为网篮组织,主要由大量集束α相及少量β相组成。空冷时随着热处理温度的升高,初生α相逐渐转变为β相;之后随着温度的升高,β晶粒长大。该合金的强度随着冷却速度的增加而增加,WQ后的强度最大,抗拉强度和屈服强度分别达到1 270和1 160 Mpa;AC后,断面收缩率最高为40%左右,而伸长率随冷却速度增加而降低。通过观察拉伸断口的SEM形貌发现,该合金在FC和AC后所表现出的断裂方式以韧性为主,WQ后的断裂以脆性断裂为主。

The effects solution temperature and cooling rate on the microstructure and mechanical properties of Ti-3.0Al-2.3Cr-1.3Fe titanium alloy were studied by means of XRD,OM,SEM and TEM.The results indicate that the microstructure of the alloy after water quenching consists of α′ martensite and metastable β phase,those after air cooling consists of α phase and residual β phase,and those after furnace cooling is typical basketweave microstructure which consists of colony α phase and little β phase.The primary α turns to β phase with temperature increasing,and then the β grain grows bigger when the temperature is above the phase transformation temperature.The strength of this alloy increases with the cooling rate increasing,after water quenching,the tensile strength and yield strength reach to 1 270 and 1 160 MPa,respectively.The reduction of area is nearly 40% after air cooling,the elongation decreases with the cooling rate increasing.Through observation of the fracture SEM morphology,the fracture way is toughness fracture after air cooling and furnace cooling,and is brittle fracture after water quenching.