Y. GoNG et al (b) oK So Mo DEt ws Fig. 10 SEM of the cross-section of creep ruptured sample under 110 MPa(a)total morphology, (b)dimples and voids, (c) r-neighbouring voids, (d)magnification of void. Meshed FEM model of T92/HR3C steels welded joint (a)total model welded joint. ultimate void volumes may vary in a wide range of values is constrained in a wide and shallow form with only a according to different toughness of different materials small amount owing to the rigidness of matrix mat As for ductile materials like T92, the preferable tough rials. ' Meanwhile, in the process of voids growth, the ness ensures a good freedom for the voids to grow, which original voids with irregular shapes transform to uni- may lead to a great amount of deep voids. However, in formly spherical ones. This can be explained that voids terms of brittle materials like HAZ of T92, voids growth with irregular shapes possess higher surface-free energy @2010 Blackwell Publishing Ltd Fatigue Fract Engng Mater Struct 34, 83-9692 Y. GONG et al. Fig. 10 SEM of the cross-section of creep ruptured sample under 110 MPa (a) total morphology, (b) dimples and voids, (c) four-neighbouring voids, (d) magnification of void. Fig. 11 Meshed FEM model of T92/HR3C dissimilar steels welded joint (a) total model and (b) welded joint. ultimate void volumes may vary in a wide range of values according to different toughness of different materials. As for ductile materials like T92, the preferable tough￾ness ensures a good freedom for the voids to grow, which may lead to a great amount of deep voids. However, in terms of brittle materials like HAZ of T92, voids’ growth is constrained in a wide and shallow form with only a small amount owing to the rigidness of matrix mate￾rials.52 Meanwhile, in the process of voids growth, the original voids with irregular shapes transform to uni￾formly spherical ones. This can be explained that voids with irregular shapes possess higher surface-free energy, c 2010 Blackwell Publishing Ltd. Fatigue Fract Engng Mater Struct 34, 83–96