(北京航空材料研究院， 北京 100095)
摘 要: 研究了熱變形溫度從（tβ-25 ℃）~（tβ+20 ℃）變化時(shí)， 對(duì)TC18鈦合金模鍛件顯微組織和拉伸、 沖擊、 斷裂韌度等主要力學(xué)性能的影響。 結(jié)果表明： 合金強(qiáng)度隨變形溫度升高變化不大，均在1 200 MPa左右； 而塑性、 沖擊韌性以及斷裂韌度等性能指標(biāo)對(duì)熱變形溫度變化反應(yīng)敏感； 兩相區(qū)變形時(shí)獲得雙態(tài)組織，合金的塑性和沖擊韌性較高，Ψ≥40%，aKU≥40 J/cm2； 但斷裂韌度偏低， KIC<50 MPa·m1/2。 β區(qū)變形時(shí)獲得片狀組織，合金具有較高的斷裂韌度，KIC>50 MPa·m1/2； 但塑性和沖擊韌性較低， Ψ≥20%，aKU≥25 J/cm2。 在相變點(diǎn)附近變形時(shí)容易導(dǎo)致合金組織和性能出現(xiàn)不均勻性。
關(guān)鍵字: TC18鈦合金； 熱變形溫度； 顯微組織； 力學(xué)性能
（Beijing Institute of Aeronautical Materials， Beijng 100095, China）
Abstract: The influence of die forging temperature (changing from tβ-25 ℃ to tβ+20 ℃) on microstructure and mechanical properties such as tensile, impact and fracture toughness are studied when the other parameters kept consistent. The results show that ultimate strength of TC18(Ti-5Al-5Mo-5V-1Cr-1Fe) alloy remains at about 1 200 MPa when the die forging temperature increases. The ductility, impact property and fracture toughness are sensitive with the variety of die forging temperature. When deforming in α-β field, bimodel structure can be obtained. Ductility and impact toughness of the alloy are relatively high, but the fracture toughness is relatively low. Under this condition, the value of reduction of area and aKU are over 40% and 40 J/cm2, respectively; KIC is lower than 50 MPa·m1/2. When deforming in β field, lamellar structure can be obtained. The fracture toughness is relatively high, but ductility and impact toughness are lower than α-β field deforming. Under this condition, KIC is over 50 MPa·m1/2, the value of reduction of area and aKU are over 20% and 25 J/cm2, respectively. When deforming near beta transition point, it may lead to the uncertainty of microstructure and properties of TC18 alloy.
Key words: TC18 alloy; hot deformation temperature; microstructure; mechanical properties
