An experimental investigation was conducted on 16MnR, a pressure vessel material widely used in China. Standard compact specimens were subjected to several different R-ratios (the ratio of the minimum load over the maximum load in a loading cycle) and loading amplitudes. Three different notch sizes ranging from very sharp notch to blunt notch were used. In addition to constant amplitude load, experiments were conducted with overloads being applied at different crack lengths. Two-step high-low sequence loading experiments were conducted to study the influence of the loading sequence. The experimental results show that the R-ratio has an insignificant influence on crack growth of the material. A single overload at the start of crack growth from a notch results in a crack arrest. The application of an overload during a constant amplitude loading experiment retards the crack growth significantly. A higher constant amplitude loading history has a great influence on the crack growth in the subsequent lower constant amplitude loading. The size of the notch together with the R-ratio has a great influence on the early crack growth from the notch.

This content is only available via PDF.
You do not currently have access to this content.