Effects of geometry and combined loading on steady-state creep stresses in welded branches

Mismatch effect in creep properties on creep crack growth behavior in welded joints

“…Thus, three cases of MF > 1, MF = 1 and MF < 1 refer to creep soft material, creep match and creep hard material, respectively. This type of design of configurations of mismatch in creep properties was widely used in the literature [5][6][7][19][20][21].…”

“…However, only a few mechanical analyses for the material constraint effect on CCG behavior due to the mismatch in creep properties between different materials in welded joints could be found in the literature. Lee et al [19] and Han et al [20,21] defined a mismatch factor about creep constant and exponent of Norton's law between different materials in weldment to quantify the mismatch effect in creep properties on the distribution of steady-state stress. Tu et al [22,23] and Xuan et al [24] studied the influence of material mismatch on the evaluation of the time-dependent fracture mechanics parameters C(t) and C ⁄ .…”

Quantification of creep stresses within HAZ in welded branch junctions

“…For overmatched cases, magnitudes of (σ e ) m /(σ e ) b are slightly different, but variations are similar to those for undermatched cases. As we have already quantified stresses in the weld in our previous works, 3,4 the results in Fig. 4 suggest that quantification of the HAZ stresses can be also possible.…”

“…For combined loading (pressure and in‐plane bending), the slopes should be bounded. In fact, it has been shown in our previous work that the slopes of the section‐averaged normalized equivalent stress versus mismatch factor curves under combined pressure and bending were bounded. To confirm this for the HAZ, calculations are performed for combined pressure and bending loading.…”

“…A = creep constant, see Eq. (1) E = Young's modulus FE = finite element HAZ = heat-affected zone M, P = in-plane bending moment and internal pressure MF = mismatch factor, see Eqs (2)(3)(4) or Eq. (6) n = creep exponent r, R = branch and main pipe mean radius, respectively t, T = branch and main pipe thickness, respectively ξ = coordinate along the centre line in the weld metal, see Fig.…”