Study on the Retardation Effect of Overload on the Corrosion Fatigue Crack Propagation Al-Alloy used for the Shipbuilding

J. Ocean Eng. Technol. 1988;2(2):122-129.

Lim Uh-Joh,Lee Jong-Rark,Lee Jin-Yeol

과하중에 의한 선박용 알루미늄 합금재의 부식피로 파괴지연에 관한 연구

임우조,이종락,이진열

부산수산대학교 박용기계공학과,여수수산대학교 선박기계공학과,한국해양대학

Keywords: Corrosion Fatigue, Specific Resistance, Overload Ratio, Retardation Parameter, Crack Growth Rate, Corrosion Sensitivity, Stress Intensity Factor

핵심용어: 부식피로, 비저항, 과하중비, 지연계수, 구열진전속도, 부식감수성, 응력확대계수

Abstract

Recently with the rapid development in marine and shipbuliding industries such as marine structures, ship and chemical plants, there occurs much interest in the study of corrosion fatigue characteristics which was closed up an important role in mechanical design. In this study, the 5086 Al-alloy was tested by use of rotary bending fatigue tester. The retardation effect of overload on the corrosion fatigue crack propagation in sea environment was quantitatively studied. 1) Retardation effect of corrosion fatigue crack propagation is most eminent when overload ratio is 1.52, overload magnitude corresponds to about 77% and 55% of yield strength and tensile strength respectively. 2) After overload ratio 1.52 was used, retardation of corrosion fatigue crack growth rate is largely retarded and quasi-threshold stress intensity factor range($Delta extrm{K}_{th}$) appears. 3) According to m of experimental constant, retardation effect of corrosion fatigue crack propagation corresponds to about 25% of constant stress amplitude when overload ratio is 1.52. 4) When overload ratio 1.52 was used, retardation parameter (RP) decreases to about 0.43 and corrosion sensitivity (S)decreses to about 2.1.