Inverse surface integrity problem in ultrasonic impact-treated AISI 304 stainless steel components

The inverse problem for surface integrity is still not solved in practice during high-performance component manufacturing, i.e., it is not possible selecting an appropriate process as well as process parameters in advance according to the given surface integrity required for the high performance. The desired surface integrity is usually created by trial and error based on an iterative approach due to lack of quantitative correlations between the loads of a process and the surface integrity variations during manufacturing. The inverse surface integrity problem is studied for manufacturing AISI 304 stainless steel components by employing an ultrasonic impact treatment (UIT) to achieve an enhanced fatigue performance. The correlations are explored between the process loads of mechanical impact, corresponding material loading within the treated component and surface integrity change in the surface layer due to surface modification. Based on experimental and numerical studies, such correlations of UIT process are identified primarily as the quantitative correlation between external mechanical load and material loading of strain and stress, and that between material loading and changes in surface integrity parameters such as residual stress and microhardness due to surface modification. It is demonstrated that a knowledge-based solution of the inverse surface integrity problem is possibly achieved by establishing the correlations to derive process parameters from a given surface integrity for manufacturing of high-performance components.