In second chapter, the mechanisms of crack nucleation and propagation are explained in detailed.
论文的第二部分对微裂纹的形核机理及扩展机理进行了详细的阐述。
It is also showed that the critical strain values of crack nucleation decrease with the increase of the size of inclusions.
结果还表明，随着夹杂物尺寸的增加，裂纹临界形核应变降低。
The high stress concentration effect of notch can accelerate the process of fatigue crack nucleation in the notch specimen.
缺口试样在缺口的高应力集中效应下，加快疲劳裂纹形核过程。
Crack nucleation and propagation in wear-resistant bainite ductile cast iron were investigated by press trace method and SEM.
采用压痕法及扫描电镜观察，研究了抗磨贝氏体球铁中裂纹的形核与扩展。
The crack nucleation energy and the propagation energy were measured under impact and tensile testing. The fracture surface was examined by SEM.
测定了析出相的类型和组成，测试和计算了冲击、拉伸状态下裂纹的形核能与扩展能，并通过SEM研究了断面形貌。
The control that accidents and fractures of crack nucleation, propagation and washout in drill pipes are importance steps to keep drill pipes safe run.
钻柱裂纹成核、扩展、刺漏等事故及断裂的控制是确保钻杆在钻井中运行安全的重要措施。
The results have shown that the incubation period of crack nucleation decreases and the propagation rate of crack increases with increasing the cyclic temperature.
试验结果表明，随着循环温度的增高，裂纹形核孕育期缩短， 裂纹扩展速率增大；
The incubation period of crack nucleation decreases and the crack propagation rate increases with the increase of thermal cycling temperature and cooling rate in the cycle.
随循环温度和冷却速率的增加，裂纹形核的孕育期缩短，裂纹扩展速率增加。
Nucleation of crack is due to dislocation pile-up mechanism and elastic anisotropy mechanism.
裂纹形核主要是通过位错堆积、晶界角源及弹性各向异性三种机理产生的。
The crack formation of thermal shock fatigue is related to the nucleation, growth and join of microvoid.
热冲击疲劳裂纹的形成与微孔洞的形核、长大和连通有关。
The stress whitening can be clearly seen on the fatigue fracture surface and its region is the initiation and nucleation of fatigue crack which is the main part of total fatigue life.
疲劳断口有应力发白现象；应力发白区为疲劳裂纹形核和萌生区，其寿命占疲劳总寿命的大部分；
The computational results clearly show the processes of nucleation and the radiation of the dislocation around the tip of the crack.
计算结果清楚地揭示了裂纹尖端位错成核与发射过程。
The results show that the crack is formed by acting of center void and intergranular cracks. Some technic modifcation of the smelting process is raise to prevent nucleation of the cracks.
经检验分析认为这种裂纹是缩孔与晶间裂纹的结合体，并提出了一些解决方法。
The results show that the crack is formed by acting of center void and intergranular cracks. Some technic modifcation of the smelting process is raise to prevent nucleation of the cracks.
经检验分析认为这种裂纹是缩孔与晶间裂纹的结合体，并提出了一些解决方法。
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