13th International Conference on Fracture June 16–21, 2013, Beijing, China 7 Fig.5 plots KIC against F in which the Xo 1/2(marked by o) , is substituted for Xf 1/2 (marked by ●) i.e. F=Xo 1/2[σf (1+N)/2N/ σy (1-N)/2N] and the major effect of ε pc is evaded. Comparing Fig.1 with Fig.5 it is apparent that when the major effect of εpc is evaded the relation between KIC and F is more stringed. The scatter in KIC at an identical F is reduced to about 21.7MPam-1/2 in Fig.5 from 55.8MPam-1/2 in Fig.1. It means that through moving the cleavage site from the right side to the left side the scatter in εpc (0.0035 to 0.1829) could have caused about 34.1MPam-1/2 in scatter of KIC. 0 100 200 300 400 0 40 80 120 160 KIc(MPam-1/2) F (MPam-1/2) Figure 5. KIC plotted against F=Xo 1/2[σf (1+N)/2N/ σ y (1-N)/2N] for a normalized C-Mn steel ● for Xf originally on left side of DMS ○ for Xo originally on right side of DMS Fig.6 plots KIC against Xo 1/2, where Xo is modified from Xf and the major effect of variation of εpc is evaded. Comparing it with Fig.2, it also shown that the scatter at same Xo 1/2 could be much reduced from 77.5 MPam-1/2 to about 43.4 MPam-1/2, part of which(about 21.7 MPam-1/2) is caused by the variation of σf. Thus both Fig.5 and Fig.6 show the effects of the variation of εpc (0.0035 to 0.1829) on the scatter of KIC account for about 34.1 MPam-1/2. 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0 40 80 120 160 K1cN K1c(MPam-1/2) XO 1/2 (mm1/2) Figure 6. KIC plotted against Xo 1/2 for a normalized C-Mn steel [1]
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