Fig. 1 Welded joint schematic and CT specimen: a method of removing the CT specimen from the welded joint, b the shape and dimensions of CT specimens used in FCG tests

Fig. 2 FCG rate (da/dN) versus stress intensity factor range (ΔK) for 9Cr-HAZ

Fig. 3 Morphologies of dissimilar welded joint: a the overall microstructure of the joint, b columnar grain in WM; c morphology of WM center; d equiaxed grains in WM

Fig. 4 Morphologies of 9Cr-HAZ: a microstructure morphology; b coarse grain zone; c fine grain zone

Fig. 5 Micro-hardness distribution in 9Cr/CrMoV welded joint

Fig. 6 Results of line scanning of CEZ and CDZ: a carbon concentration of the CEZ and CDZ; b magnified morphology of precipitated phase in CEZ; c magnified morphology of precipitated phase in CDZ

Fig. 7 Overall crack propagation path of 9Cr-HAZ at: a R?=?0.1, b R?=?0.3, c R?=?0.5

Fig. 8 FCG path of 9Cr-HAZ at R?=?0.1: a fine grain zone of the crack left side at the early stage of propagation, b coarse grain zone of the crack right side at the early stage of propagation, c macroscopic morphology of crack deflection position, d-f crack propagation in each micro-region

Fig. 9 Micro-morphologies of fracture surface in different positions of 9Cr-HAZ: a macroscopic morphology; b and c morphologies of crack position in 9Cr-HAZ; d fracture morphology of CDZ; e morphology of crack deflection position; f and g dimples in CDZ

Fig. 10 Fracture morphologies of 9Cr-HAZ crack deflection position: b and c secondary cracks before crack deflection; a and d morphologies of deflection position

Fig. 11 EBSD analysis of crack deflection path in 9Cr-HAZ: a macroscopic morphology of crack path; b-e IPF images of each micro-region; f-i schematics of deformation in each micro-region

Fig. 12 Stress concentration a and plastic deformation b distributions of 9Cr-HAZ crack tip

Fig. 13 Schematic of fatigue crack deflection mechanism