The influence of porosity on low-cycle fatigue.

摘要

The influence of porosity on low cycle fatigue has been examined using powder-processed titanium as a model material. The presence of even low levels of porosity (0.4%) affects the cyclic flow behavior and is very detrimental to low cycle fatigue life. An analysis has been performed by considering low cycle fatigue in terms of the following stages: (1) the initiation of 15;The above experimental observations have been modeled both quantitatively and qualitatively. Modeling pores at a free surface as through-thickness holes in a plastically deforming matrix and utilizing a Coffin-Manson failure criterion on a local scale, we have theoretically predicted the number of cycles to initiate a microcrack. The results of those predictions agree very well with the experimental observations of crack initiation in the porous titanium specimens. The linking of short cracks has been addressed semi-quantitatively by considering the growth of a crack of mean length which depends on both the density and the size distribution of microcracks. The linking results indicated that once the mean-crack-length reaches a critical size (