Strain Controlled Fatigue Behavior of Weld Metal and Heat-Affected Base Metal in A36 and A514 Steel Welds
by
Y. Higashida
F. V. Lawrence
Department of Metallurgy and Mining Engineering
Abstract
The mechanical and low cycle fatigue properties and cyclic mean stress relaxation behavior of base metal, heat-affected zone (HAZ), and one- and two-pass weld metals were investigated for ASTM A36 and A514 steel welds. The HAZ specimens used in this study were synthetically produced by a weld thermal simulator. In order to obtain low cycle fatigue properties, constant amplitude, completely reversed, uniaxial strain controlled tests were employed. Using the data obtained in this investigation, fatigue crack initiation lives of hypothetical butt welds were predicted by simple calculations.
The results and analyses suggest the following conclusions. The difference in fatigue resistance among these materials was greatest at long lives. The ranking of fatigue resistances at 106 cycles were: one-pass weld metal (highest), HAZ, two-pass weld metal, base metal (lowest) for the A36 steel weld, and HAZ (highest), two pass weld metal, base metal, one-pass weld metal (lowest) for the A514 steel weld. The effect of the mean stress on the fatigue life decreased very rapidly with cycles for A36 steel welds but did not for A514 steel welds. Hardness was a useful measure of low cycle fatigue behavior of the HAZs and weld metals.
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