A Study of the SCC Propagation Characteristics da/dt of welded Joints

By means of ponstant displacement WOL specimens, characteristics and rates of SCC propagation on parent metals, welded metals and heat affected zone of steels of 16Mn and 09MnTiCuRe types Ⅰ and Ⅱ as well as transversal and longitudinal propagation of welded joints are measured and demonstrated in this paper. Macro and micro fractographs are carefully observed and analyzed. Two kinds of heat simulated specimens of fusion line are made that their resistance to H₂S stress corrosion is proved to be the minimum. The front of the longitudinal propagated crack at the fusion line presents a "Concave" shape and the curve da/dt-K₁ of the transversal propagation appears in "Saddle" pattern. This provides the SCC propagation characteristics of welded joints with new information.