TMCP강의 용접이방성 및 과대하중이 피로균열진전에 미치는 영향

The TMCP Steel s Weld Anisotropy and the Overload Effect on the Fatigue Crack Propagation

Recently the most of marine structures was bing composed by the welding on distinguished development of welding technology. However, a lot of welding zone fatigue crack accident was reported annually. This accidents coursed by attack in large high waves, or a storm etc. Actually, acted loading power on marine structures was not regular waved loadings but the irregular waved loadings. These irregular wave loadings is much effected on the fatigue life. In this point, the important thing is investigating the effect on fatigue crack propagation of overloading by simplify the irregular loadings. The studies of these overloading effects on welded structures will be much helpful to prevent the fatigue crack accidents or the marine structure s life. Therefore, on this studies, We used welding heat effected sample pieces that s a pressed steel material by newly developed Thermo Mechanical Control Process(TMCP) method for the marine structures. And we investigate the effect of fatigue crack propagation and crack open/closing behavior on welding heat effects by this sample pieces, and also we investigate the most important overloading effects of the irregular wave loadings on that fatigue crack propagation and crack open/closing behavior. We investigated that the fatigue crack propagation was located on the low side than the main body. And didn t found the weld anisotropy effect, but on the case of welded substance, the fatigue crack propagation velocity on the overload was more delate on the breadth direction than pressed direction, therefore we can consider the delate phenomena of crack propagation was not accomplished due to the crack open/close phenomena.