Influence of Surface Finish on Fatigue Life of Steel Specimens Subjected to Pure Bending

Abstract

It has long been appreciated that surface conditions exert significant influence on fatigue behavior. The new capabilities of identifying and measuring surface parameters together with the significant development in data analysis by computers have facilitated the establishment of analytical models to quantify this influence. This paper displays the effect of surface Amplitude, Spacing and Hybrid parameters on the number of cycles to failure of standard steel specimens subjected to pure bending fatigue tests. Specimens were polished to four different grades and surface texture was evaluated for each grade using a Rank Taylor Hobson-5 surface analyzer. High cycle fatigue (HCF) test were conducted at a constant stress level of (0.75) of the yield stress with (10) replications for each surface grade. Results of the fatigue tests - together w'th all surface parameters and test conditions - were fed into an SPSS computer package. Fatigue life of the steel specimens was significantly affected by the change in surface parameters and the number of cycles to failure could be mathematically predicted - to a high level of confidence - from those parameters.