異種熔接材의 疲勞크랙傳播擧動에 關한 硏究 = Study on the Fatigue Crack Propagation Bahaviors in Dissimilar Weldments of Mild Steel and Stainless Steel

다국어 초록 (Multilingual Abstract)

In order to investigate the fatigue crack propagation behaviors of dissimilar weld joints, submerged arc butt welding is used for welding mild steel (SB 34) and austenitic stainless (STS 304).
The dissimilar weld joint consists of (1) the unaffected base metal of mild steel (SB 34), (2) the unaffected base metal of stainless steel (STS 304), (3) the heataffected zone of mild steel (HAZ), and (4) the deposit metal zone (DMZ).
Unidirectional bending fatigue tests have been carried out in these four zones with quarter-circular shape corner crack. Obtained results are summarized as follows.
(1) The relation between the crack aspect ratio ?? and crack depth to plate thickness ratio ?? of dissimilar weld joints are expressed by following eq. in the range of 0.2<??<0.7
??
Where G and αare material constant dependent upon the magnitude of bending stress.
(2) The relationship between the fatigue crack propagation rate and stress intensity factor range ?? is properly applied to dissimilar weld joint, where its exponent (m) are 2.46 to 3.25.
(3) The fatigue crack propagation rate of dissimilar weld joint within the same stress intensity factor range is the largest at the heat-affected zone of mild steel and nexts are the unaffected base metal of mild steel, the unaffected base metal of stainless steel and the deposit metal zone in order.