11615 SCC Growth Rates

SCC growth rates are determined by adopting fracture mechanics test methods [27]. In this case compact tension specimens containing a preexisting defect (crack) are used (see Fig. 11.12). Crack extension is monitored as a function of time, and a plot of crack growth rate (da/dt) vs. stress intensity factor (K) is derived. This latter parameter is based upon Eq. 11.15:

where aapp is the applied tensile stress, Y is a factor dependent upon specimen geometry, and a is the crack length.

Figure 11.13 presents a typical SCC growth curve. The important features of this plot are (i) a threshold stress intensity KISCC value below which crack growth does not occur, (ii) a limited crack growth plateau where the crack velocity is

0 0

Post a comment