Long-Term Creep-Crack Growth Behavior of Type 316 Stainless Steel

For most engineering applications, crack-growth rates of 10⁻⁹ m/s or less are of practical interest, but this is the regime where little creep-crack growth data currently are available. Long-term creep-crack growth experiments of about 1000 h or more duration are required to develop such data. In the present study, creep-crack growth data were developed at rates between 10⁻¹¹ and 10⁻⁷ m/s for Type 316 stainless steel. Three specimen configurations were used: compact type (CT); center-cracked tension (CCT); and multiple edge-notch tension (MENT). The CT and CCT specimens had long (25 to 35 mm) and the MENT specimens had short (100 to 500 μm) cracks. Creep-crack growth rate was evaluated both in terms of the linear elastic stress intensity factor K and the C*-integral. It was concluded that the C*-integral is useful for characterizing long-term as well as short-term creep-crack growth rate data for both short and long cracks on a consistent basis.