Effect of Lack of Penetration on Fatigue Resistance of High-strength Structural Steel Welds
U.S. Construction Engineering Research Laboratory, 1977 - Steel, Structural - 28 pages
Zero-to-tension fatigue tests were carried out on double-V butt welds of ASTM A514 steel plate, 20 mm in thickness, which contained full-length lack of penetration (LOP) defects. The fatigue crack initiation and propagation portions of the specimens' fatigue lives were experimentally separated. Compression-to-tension fatigue tests were carried out on prime base plate, as-welded sound joints, and reinforcement-removed welds to experimentally determine the fatigue strength reduction factor (Kf) of the LOP defects. LOP defects as small as 0.5 mm wide had a profound effect on fatigue life. The fatigue crack initiation life was found to be short-only 10 percent of the total life-and could be predicted using fatigue crack initiation concepts. The use of KF(max), the maximum possible fatigue strength reduction factor, was found to be appropriate. In a separate substudy, the fatigue resistance of ASTM A514 butt-welded joints containing clustered porosity was determined. (Author).
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2OOO 3OOO 5OOO 3OO 5OO 7OO ASTM Base Metal clustered porosity containing full-length LOP containing LOP defects crack advance Cycles To Failure diameter reduced section Failure Figure fatigue crack initiation Fatigue Crack Propagation fatigue data fatigue resistance fatigue strength reduction fatigue tests Fracture mode Crack full-length LOP defects Gross Stress Range initiation and propagation LACK OF PENETRATION limit for sound LOP in Specimen LOP WM LOP lower confidence limit NUMBER OOO 2OOO 3OOO Peak dynamic strain Peterson's equation power law predicted prime base plate propagation portions range of 206 reduction factor Kf reinforcement intact Retested at higher S-N curve sound butt welds sound welds strain change strain gages strength reduction factor stress concentration stress intensity factor Stress Range MPa Table test specimens tips of LOP Total Fatigue Weld Metal welds containing LOP welds with reinforcement width LOP Width of LOP WM LOP WM Yield Strength Young's modulus