Session: DA-03-01 Fatigue 1-Research on Effects of Surface Finishing and Mean Stress on Fatigue Lives of Notched Specimens

Paper Number: 124661

124661 - Research on Effects of Surface Finishing and Mean Stress on Fatigue Lives of Notched Specimens - Surface Finishing Effect for Notched Specimens of Low Alloy Steel - 

DFC and DFC2 subcommittees in the Japan Welding Engineering Society developed a new approach of fatigue analysis method. This fatigue analysis method has been made several modifications and incorporated into the JSME Environmental Fatigue Evaluation Method 2022 Edition (JSME S NF1-2022). Research on effects of surface finishing and mean stress on fatigue lives of notched specimens have been followed by DFC3 and DFC4 subcommittees. In this paper, overview of the outcomes of DFC3 and DFC4 subcommittees is introduced.
In the previous study PVP2022-84695, fatigue tests using roughness as a parameter were conducted on 8mm smooth specimens of low alloy steel of SQV2A to evaluate the relationship between fatigue strength reduction factor for surface finish effect (Ksf) and roughness Rz. These fatigue test data support the Ksf equation of JSME.
In this study, the effect of surface roughness due to emery polishing and machining (Rz=25 μm) was confirmed for 8mm notched specimens. The difference in specimen displacement is measured with an extensometer, and a stoppage test is carried out. However, the crack depth at the finish of the fatigue test is not constant because it depends on the test conditions such as stress amplitude and extensometer position, and the definition of fatigue life differs from that of the strain control test. Therefore, the fatigue life is defined as the estimated number of cycles with a crack length of 2 mm, which was considered in another study.

Presenting Author: Yuichiro Nomura Mitsubishi Heavy Industries, Ltd

Presenting Author Biography: I belong to the strength research laboratory of Mitsubishi Heavy Industries. In the past, it has mainly carried out research on the intensity relation of the atomic energy relation.
Specifically, environmental fatigue evaluation in the PWR primary system environment, monitoring tests to determine irradiation embrittlement of reactor pressure vessels, and SCC by cold working of stainless steel piping are the main research topics. In recent years, the strength evaluation in hydrogen environment has also been carried out.

Authors:

Yuichiro Nomura Mitsubishi Heavy Industries, Ltd
Daiki Takagoshi Mitsubishi Heavy Industries, Ltd
Seiji Asada Mitsubishi Heavy Industries, Ltd
Atsushi Sugeta Hiroshima University
Yoshihide Kitamura The Kansai Electric Power Co., Inc