Study on fatigue crack propagation behavior of welded joints of EH36 and EH690 dissimilar steels
GUO Shihao
GAO Xudong
SHAO Yongbo
Abstract：[Objective]EH36 and EH690 high-strength steels are widely used in offshore platforms,but their dissimilar welded joints have poor fatigue resistance and are prone to fracture failure.This study aims to investigate the fatigue crack propagation behavior and life characteristics of these welded joints under different stress ratios,providing a theoretical basis for safety assessment and fatigue design of marine steel structures.[Methods]Firstly,welded joints of EH36 and EH690 dis-similar steels were prepared using gas metal arc welding(GMAW),and standard compact tension specimens were machined.Secondly,fatigue crack propagation tests were conducted on the weld zone,heat-affected zone,and EH36 base metal under three stress ratios(R=0.1,0.3,0.5).Thirdly,the fatigue crack growth rates were calculated based on test data,and material constants C and m were obtained by fitting the Paris formula.Finally,the microscopic morphology of fatigue fractures was analyzed using scanning electron microscopy(SEM).[Results]The results show that for the same crack propagation distance,the number of fatigue cycles increases with the yield strength of the material.The welding residual tensile stress in the heat affected zone(HAZ)increases the mean stress level of the cyclic stress,thereby increasing the fatigue crack growth rate and reducing the fatigue life of the component.The fracture surface exhibits quasi-cleavage characteristics.
Keywords：EH36 steelEH690 steelStress ratioFatigue crack growthMicro-morphology
Publication Date：2026-01-31
Online Publishing Date：2026-09-12(First online date of this platform, not the publication date of the document)
Pages：9( 63-71 )