• Title/Summary/Keyword: 응력 변동

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The Propagation Behaviour of the Fatigue Crack in the Compact Tension Specimens of the Welded Structural Steels (On according to the difference of the welding direction, the input heat level, the strength of weld material and so on) (용접(鎔接)이음한 구조강(構造鋼)의 소인장시험편(小引張試驗片)에서의 피로구열진전거동(疲勞龜裂進展擧動) (용접방향(鎔接方向), 입열량(入熱量), 용접재료(鎔接材料)의 강도(强度) 등이 다를 때))

  • Chang, Dong Il;Chung, Yeong Wha
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.4 no.2
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    • pp.133-142
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    • 1984

  • With the weld-joined compact tension specimens compared with each other, that is, transverse and lengthwise about the crack propagation direction, high and low in the input heat level, same as and lower than the base metal in the strength of weld material, the fatigue test were performed. With these data, the log-log curves between the fatigue crack propagation rate ${\frac{da}{dN}}$ and the transition range of the stress intensity factor ${\Delta}K$ ahead the crack tip were drawed. These curves were compared and estimated among each compared specimens, among each zones, that is, the base metal, the heat-affected metal and the weld-mixed metal, and between this study and the past studies. Basically, Little difference in the slope of the $da/dN-{\Delta}K$ relation was showed in all the welded directions, all the input heat levels and all the zones. But, First, to comparison with in the past studies about the base metals, it was showed that da/dN started in the much later rate, increased faster and stoped in the little faster rate. Second, it was showed that, near the time the crack's going from the heat-affected zone to the weld-mixed metal da/dN decreased a little for a while. Third, in the lengthwise weld compared with the transverse weld, in the high input heat weld compared with the low input heat weld in the case used the weld material of the same strength as the base metal, in the opposite case in the case used the one of the lower strength than the base metal, in the case used the weld material of the same strength as compared with the lower strength than the base metal beside the high input heat and the lengthwise weld, it was showed that the crack occured earlier in lower ${\Delta}K$ and later da/dN, the curves went with the same slope. Forth, in the lengthwise weld compared with the transverse weld in the low input heat weld, in the low input heat weld compared with the high input heat weld, it was showed that da/dN went with the lower level.

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