对熔模精密铸造的近α型TG6钛合金依次进行了热等静压和不同温度退火处理,研究了不同状态合金的显微组织和拉伸性能.结果表明:铸态合金的显微组织主要为魏氏组织,组织中存在缩松缺陷;其室温抗拉强度和伸长率分别为871.3 MPa,0.8％,缩松处为断裂源.900℃热等静压处理消除了缩松缺陷,合金的室温伸长率提高至3.7％,拉伸断口呈准解理断裂特征.经700～800℃退火处理后,合金组织中的β板条部分溶解并析出条状及颗粒状硅化物,在α板条中弥散分布着α2相析出物;其室温伸长率提高到11％以上,室温及550℃拉伸断口为韧性断裂和解理断裂共存的混合型断口,而650℃和700℃拉伸断口呈腐蚀开裂特征.
The hot isostatic pressing and annealing treatment at different temperatures were successively conducted on a near-α TG6 titanium alloy by precision casting,and then the microstructure and tensile properties of the alloy in different states was studied.The results show that the microstructure of the cast alloy mainly consisted of Widmanstatten structure,and the shrinkage defect existed in the microstructure;the room temperature tensile strength reached 871.3 MPa,while the elongation was only 0.8％;the shrinkage defect became the crack initiation source.After hot isostatic pressing at 900 ℃,the shrinkage defect was eliminated,the room temperature elongation increased to 3.7％,and the tensile fracture showed features of quasi cleavage fracture.After annealing at temperatures of 700 ℃-800 ℃,β lath in the alloy microstructure was dissolved partially and band-like and granular silicide precipitated,meanwhile the α2 phase dispersively distributed in the α lath;the room temperature elongation was improved to over 11％,and the tensile fracture at room temperature and 550 ℃ showed a mixed fracture of cavitation and cleavage,while those at 650 ℃ and 700 ℃ showed characteristics of corrosion cracking.
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