Effect of Mechanical Heterogeneity on the Crack Driving Force of a Reactor Pressure Vessel Outlet Nozzle DMW Joint

[摘要] The welding mechanical heterogeneity, load complexity, material and geometrical structure makes it very difficult to assess the structural integrity of dissimilar metal weld (DMW) joints. Based on a numerical simulated approach of the continuous change of material mechanical property in the buttering layer, a reactor pressure vessel (RPV) outlet nozzle DMW joint with service loads is studied, effect of mechanical heterogeneity on the stress-strain field and stress triaxiality at the semi-elliptical surface crack front are discussed. The analyses show that once the crack extends into the high hardness zone of Alloy 182 buttering, the strain decreases sharply, the strain gradient increases and the crack propagation slows down. The influence of strength mismatch on the stress triaxiality at the shallow crack front is greater than that at the deep crack front. The interaction between strength mismatch and crack depth directly affects the crack growth direction.

[发布机构] School of Science, Xi'An University of Science and Technology, Xi'an; 710054, China^1;School of Mechanical Engineering, Xi'An University of Science and Technology, Xi'an; 710054, China^2

[效力级别] 无线电电子学

[关键词] Crack driving force;Crack-growth direction;Dissimilar metal weld joints;Geometrical structure;Mechanical heterogeneity;Numerical simulated;Reactor Pressure Vessel;Semi-elliptical surface cracks