Abstract
An investigation of subcritical crack growth in C–Mn steels at 360°C has been conducted to provide data relevant to the assessment of the long-term integrity of cold-formed bends in boiler integral pipework systems. The material was obtained from bends that exhibited hardnesses towards the top and bottom of the usually observed range and which had been in service for approximately 63000 h. Crack growth rates were found to be a function of specimen displacement rates, and despite evidence that growth may have occurred under non-steady-state conditions, good correlation of the data was obtained using the C* parameter. Material hardness was found to be a major factor in determining resistance to cracking, although the trends observed in creep and crack growth properties suggest that its effect may be reduced at long exposure times.
MST/509