Calibration of Contact Depth for Evaluating Residual Stress using Instrumented Indentation Testing

연속압입시험법을 이용한 원전구조물의 잔류응력 평가를 위한 접촉깊이의 보정

Residual stress is the key parameter for reliability and lifetime assessment because it can reduce the fatigue strength and fracture properties of industrial structures. Recently, instrumented indentation testing (IIT) has been widely used for evaluating it, since it does not need specific specimen and time-consuming procedure. However, conventional Oliver-Pharr method, which is used for calibrating contact depth to analyze indentation load-depth curve, cannot estimate plastic pile-up between indenter and surface of specimen. Here, we introduce f parameter which is the ratio of contact depth and maximum depth, to consider pile-up height. And, its application for evaluating residual stress of weldment is introduced.