Closure development and crack opening displacement in the short crack regime for fine and coarse grained A533B steel

This paper reports the results of an investigation of the closure, growth rate and crack opening displacement (COD) behaviour of small cracks in A533B steel. A laser-based interferometric strain/displacement measurement system was used in the work to quantify closure and COD values in both fine and coarse grained microstructures at stress ratios of -1 and 0.1. The data obtained clarify the relative dominance of closure or microstructure in the two conditions of the steel and appear to shed some light on the size of crack tip plastic zones for small cracks in the two microstructures. (author)