激光辐照下预内压低碳钢圆柱壳爆裂断口分析

FRACTOGRAPHIC ANALYSIS OF LOW CARBON STEEL CYLINDRICAL SHELLS DAMAGED BY INNER PRESSURE AND SURFACE LASER IRRADIATION

通过实验揭示了预内压低碳钢薄柱壳在激光辐照下裂纹萌生、扩展和止裂过程的较完整物理图象。对断口特性进行了深入分析，发现辐照区上裂纹的形成和扩展机制以韧性为主，断口在柱壳壁厚度方向有明显分层，如外层为塑性变形层，内层是韧窝或层状撕裂，部分试件的最内层出现脆性石头状断口。给出了激光辐照区应力分布与裂纹萌生之间的关系，同时探讨了激光辐照区材料金相组织变化对材料细观损伤和初始裂纹萌生的影响，有助于进一步对激光辐照下柱壳的断裂问题进行更深入的理论研究。

In this paper,the fractographs of low carbon steel cylindrical tanks damaged by inner pressure and laser irradiation have been analyzed .It is found that the main mechanism of crack formation and development in the area irradiated by the laser beam is ductile.Most of these fractographs have obviously layers on the shell wall due to stress distribution and deformation ,for example ,the outer one is induced by plastic deformation ,the inner one consists of many ductile dimples or layers teared. Some fractographs show that the inner one is brittle like stone .The relations between the stress distribution and cracks,also the development process of crack,are discussed in this paper.The metallograph in the area irrdiated by the laser is focused on to find some evidence to explain its original damage induced by the laser beam.All information provided here are conducive to a better theoretical study on this problem.