Consideration of Shot Peening Condition Focused on Improvement of Stress Corrosion Cracking Resistance by Robust Optimization

Abstract

Stress corrosion cracking is known to be affected by surface characteristics such as surface roughness, surface hardness and residual stress from past studies. As a processing for controlling such surface characteristics, shot peening capable of improving fatigue resistance and stress corrosion cracking resistance by imparting compressive residual stress are mentioned. In this study, we considered shot peening condition focusing on improvement of stress corrosion cracking resistance which is the purpose by shot peening. By using the response surface model of shot peened surface characteristics and robust optimization program created by MATLAB, optimal condition and robust optimal condition that can obtain effective surface characteristics to stress corrosion cracking are derived and compared. The conclusions were as follows: (1)Two kinds of robust optimization methodology can be used different depending on purpose and application. (2)The robust optimal condition in Ra and Rz from robust optimal program is selected larger coverage compared to optimal condition. (3)In RSm and Hv, optimal condition and robust optimal condition are almost the same.