乙醇對TC4鈦合金超高周疲勞性能的影響
Influence of Alcohol on the Super Long Life Fatigue Properties of TC4 Titanium Alloy
利用超聲疲勞試驗方法分別對室溫下醫用酒精(體積分數75%)中浸泡5 min、醫用酒精浸泡5 min后再在生理鹽水中浸泡24 h、直接在生理鹽水中浸泡24 h、分析純乙醇(體積分數99.9%)中浸泡6 h、醫用酒精中浸泡6 h等處理條件下退火態Ti6Al4V(TC4)鈦合金的超高周疲勞性能進行了研究,并利用掃描電子顯微鏡(SEM)觀察疲勞斷面形貌,分析了TC4鈦合金的疲勞斷裂特性.結果表明:在104 ~ 109周次范圍內,經醫用酒精處理后TC4鈦合金的S-N曲線呈現一次階梯下降型,而未用醫用酒精處理的TC4鈦合金的S-N曲線呈現緩慢下降型;在300~700 MPa應力范圍內,醫用酒精浸泡過的TC4鈦合金試樣疲勞壽命快速下降;醫用酒精處理后的TC4鈦合金的超高周疲勞斷裂全部從表面發生、斷面較光滑且瞬斷區面積占比極小,不同于未接觸醫用酒精的TC4鈦合金試樣的穿晶塑性斷裂.
The ultrasonic fatigue test method was used to investigate the influence of alcohol on the super long life fatigue properties of annealed Ti-6Al-4V (TC4) titanium alloy which were sterillized by 75% medical alcohol for 5 min and dipped into physiological saline solution for 24 h.The fatigue properties of TC4 titanium alloy which subjected to A.R.alcohol for 6 h,directely dipped into 75% medical alcohol for 6 h,and directedly subjected to physiological saline solution for 24 h were also achieved for comparation.The results show that the S-N curves between 104~109 cycles of sterilized TC4 specimen went down with a step,while the S-N curves of specimen without sterization by medical alcohol droped down slowly.75% medical alcohol decreased the fatigue life of TC4 titanium alloy quickly in the maximum fatigue stresses from 300 MPa to 700 MPa.The fractography analysis results show that the fracture always initiated from the surface of specimen which had been sterilized by 75% medical alcohol,and the fracture surface was smooth with small final rupture region,which was different from the transcrystalline plastic fracture of the untreated specimens.

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