止裂孔-疲劳裂纹尖端相对位置对工业纯铁DT4C抗疲劳性能的影响  

Influence of relative position of crack arresting hole-fatigue crack tip on fatigue resistance for industrial pure iron steel DT4C

作　　者：刘荣伟 黄志国 李艳艳 孙立强 宋劲松 Liu Rongwei;Huang Zhiguo;Li Yanyan;Sun Liqiang;Song Jinsong(Industrial Technology Center,Hebei Petroleum University of Technology,Chengde 067000,China;Department of Mechanical Engineering,Hebei Petroleum University of Technology,Chengde 067000,China)

机构地区：[1]河北石油职业技术大学工业技术中心,河北承德067000 [2]河北石油职业技术大学机械工程系,河北承德067000

出　　处：《锻压技术》2024年第2期265-274,共10页Forging & Stamping Technology

基　　金：河北省自然科学基金资助项目(B2021411001);河北省高等学校科学技术研究项目(ZC2023188)。

摘　　要：止裂孔是金属结构件疲劳延寿的重要方法之一,但其对疲劳裂纹扩展速率及疲劳寿命的影响规律复杂多变,以工业纯铁DT4C金属板材为例,采用扩展紧凑拉伸试样(E-CT)研究了止裂孔相对疲劳裂纹尖端的不同位置(即裂纹尖端前沿材料切除量分别为0.3、0.6和0.9 mm)对含裂纹试件的疲劳寿命和裂纹扩展速率的影响规律。结果表明:由于在疲劳裂纹扩展过程中裂纹尖端沿厚度方向上扩展速率的差异及裂尖塑性区的存在,裂纹尖端前沿材料切除量对止裂孔的延寿作用具有重要影响,且影响程度差别较大。在相同疲劳载荷和应力比近似为0的情况下,裂纹尖端前沿材料切除量为0.6 mm时,试样的疲劳裂纹扩展速率和疲劳寿命改善最为明显,与常规试样相比疲劳寿命增加了2倍以上。The crack arresting holes are one of the important ways to extend the fatigue life of metal structural components,and the influ-ences on the fatigue crack propagation rate and fatigue life are complex and changeable.Therefore,for the metal plate of industrial pure iron DT4C,the influences of different positions of the crack arresting hole relative to the fatigue crack tip(i.e.,the material removal amount at the front of crack tip was 0.3,0.6 and 0.9 mm,respectively)on the fatigue life and crack propagation rate of the cracked specimen were studied by the extended compact tensile test(E-CT)specimens.The results show that due to the difference in the propaga-tion rate of crack tip along the thickness direction and the existence of the plastic zone at the crack tip during the fatigue crack propagation process,the amount of material removed at the front of crack tip has an important impact on the life extension of the crack arresting hole,and the degree of influence varies greatly.Under the same fatigue load and the stress ratio of approximately O,the fatigue crack propaga-tion rate and fatigue life of specimen are most significant when the material removal amount at the front of crack tip is O.6 mm,and com-pared with the conventional specimens,the fatigue life is increased by more than two times.

关 键 词：止裂孔 裂纹尖端 疲劳裂纹扩展速率 疲劳寿命 裂纹尖端塑性区 

分 类 号：TG11[金属学及工艺—物理冶金]