TB6钛合金疲劳小裂纹扩展行为  

Small fatigue crack growth behavior of TB6 titanium alloy

作　　者：许良 黄双君 回丽 王磊 周松 赵晴 XU Liang;HUANG Shuang-jun;HUI Li;WANG Lei;ZHOU Song;ZHAO Qing(School of Mechatronics Engineering,Shenyang AerospaceUniversity,Shenyang 110136,China;Key Laboratory ofFundamental Science for National Defense of AeronauticalDigital Manufacturing Process,Shenyang AerospaceUniversity,Shenyang 110136,China)

机构地区：[1]沈阳航空航天大学机电工程学院,沈阳110136 [2]沈阳航空航天大学航空制造工艺数字化国防重点学科实验室,沈阳110136

出　　处：《材料工程》2019年第11期171-177,共7页Journal of Materials Engineering

基　　金：国家自然科学基金资助项目(51405309);辽宁省教育厅高等学校科学研究项目(L2016033);沈阳航空航天大学航空制造工艺数字化国防重点学科实验室开放基金(SHSYS2015002)

摘　　要：为了研究TB6钛合金自然萌生小裂纹的扩展行为,针对单边缺口拉伸试样开展室温下不同应力比(R=0.1,0.5)的小裂纹扩展实验,采用复型法观测了小裂纹的萌生与扩展情况。结果表明:同一应力比下,随着应力等级的降低,小裂纹的萌生寿命由占全寿命的60%增加到80%,但应力等级对TB6钛合金小裂纹扩展速率没有明显影响。裂纹早期扩展速率受微观组织的影响大,TB6钛合金扩展速率转变临界值是200μm,一旦裂纹长度达到200μm,裂纹扩展速率将不受取向不同的晶界或晶粒影响而迅速提升。TB6钛合金疲劳小裂纹起源于试样缺口根部,所有试样的裂纹大部分为角裂纹,疲劳小裂纹萌生寿命占全寿命的绝大部分。The growth behavior of naturally-initiated small cracks in single edge notched tensile(SENT) specimen of TB6 titanium alloy was studied. Fatigue experiments were conducted under constant amplitude loading with the stress ratios R of 0.1 and 0.5 at room temperature. Small cracks were allowed to be monitored by replica method during fatigue testing. Results show that at the same stress ratio, the initiation life of crack increases from 60% to 80% of the total fatigue life with the decrease of stress level. However, the stress level has no significant effect on the crack growth rate of TB6 titanium alloy. The crack growth rate at the early stage is greatly affected by the microstructure. Once the crack length reaches 200μm, the crack growth rate will increase rapidly regardless of grain boundary or grain orientation. Small cracks of TB6 titanium alloy are originated from the sample notch root in the form of corner crack, and the major part of total fatigue life is consumed in small fatigue crack initiation phase.

关 键 词：钛合金 小裂纹 疲劳源 裂纹扩展速率 应力等级 

分 类 号：TG146.2[一般工业技术—材料科学与工程]