【摘要】：研究了準(zhǔn)β熱處理工藝窗口參數(shù)(保溫時(shí)間和加熱溫度)對損傷容限型TC4-DT鈦合金的疲勞裂紋擴(kuò)展行為的影響,并采用金相顯微鏡(OM)和掃描電鏡(SEM)從顯微組織、裂紋擴(kuò)展路徑及斷口形貌進(jìn)行了分析對比。結(jié)果表明:隨著保溫時(shí)間從5 min延長至15 min,原始β晶粒尺寸從130μm增大到230μm,轉(zhuǎn)變點(diǎn)處ΔKt由17.5 MPa·m~(1/2)增大至19.4 MPa·m~(1/2),當(dāng)10 MPa·m~(1/2)≤ΔK≤20 MPa·m~(1/2)的低應(yīng)力范圍,裂紋擴(kuò)展速率降低;隨著加熱溫度從988℃升高至998℃,原始β晶粒尺寸從130μm增大至240μm,轉(zhuǎn)變點(diǎn)處ΔKt由17.5 MPa·m~(1/2)增大至18.0 MPa·m~(1/2),轉(zhuǎn)折點(diǎn)前的裂紋擴(kuò)展區(qū)的裂紋擴(kuò)展速率降低;當(dāng)溫度繼續(xù)升高至1008℃時(shí),原始β晶粒尺寸增大至400μm,轉(zhuǎn)折點(diǎn)處ΔKt增大至20.5 MPa·m~(1/2),裂紋擴(kuò)展速率在轉(zhuǎn)折點(diǎn)附近降低,但在ΔK≥20.5 MPa·m~(1/2)的較大應(yīng)力區(qū)域時(shí),裂紋擴(kuò)展速率無明顯變化;溫度升高或保溫時(shí)間延長,裂紋擴(kuò)展路徑曲折度增加,二次裂紋數(shù)量增多、深度增加,斷口表面粗糙度降低。
[Abstract]:The effect of window parameters (holding time and heating temperature) on the fatigue crack propagation behavior of TC4-DT titanium alloy with damage tolerance was studied. The microstructure of the alloy was obtained by metallographic microscope (OM) and scanning electron microscope (SEM). The crack propagation path and fracture morphology were analyzed and compared. The results show that as the holding time increases from 5 min to 15 min, the original 尾 grain size increases from 130 渭 m to 230 渭 m, and 螖 Kt increases from 17.5 MPa m2 to 19.4 MPa m2 at the transition point. When the stress range of 10 MPa m ~ (1 / 2) 鈮，

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