Next Article in Journal
High-Velocity Impact Welding Process: A Review
Next Article in Special Issue
Retardation of Fatigue Crack Growth in Rotating Bending Specimens with Semi-Elliptical Cracks
Previous Article in Journal
Effect of Substituting CaO with BaO and CaO/Al2O3 Ratio on the Viscosity of CaO–BaO–Al2O3–CaF2–Li2O Mold Flux System
Previous Article in Special Issue
Critical Distance Default Values for Structural Steels and a Simple Formulation to Estimate the Apparent Fracture Toughness in U-Notched Conditions
Article Menu
Issue 2 (February) cover image

Export Article

Open AccessArticle
Metals 2019, 9(2), 143; https://doi.org/10.3390/met9020143

Fatigue Limit Improvement and Rendering Defects Harmless by Needle Peening for High Tensile Steel Welded Joint

1
Graduate School of Engineering, Yokohama National University, 79-5, Tokiwadai, Hodogaya-ku, Yokohama-city, Kanagawa 240-8501, Japan
2
Faculty of Engineering, Yokohama National University, Yokohama-city, Kanagawa 240-8501, Japan
3
Technology Development Group, Toyo Seiko Co., Ltd., Yatomi-city, Aichi 490-1412, Japan
*
Author to whom correspondence should be addressed.
Received: 11 January 2019 / Revised: 25 January 2019 / Accepted: 26 January 2019 / Published: 28 January 2019
(This article belongs to the Special Issue Fracture, Fatigue and Structural Integrity of Metallic Materials)
Full-Text   |   PDF [6214 KB, uploaded 28 January 2019]   |  

Abstract

The effects of needle peening (NP) on the bending fatigue limit of a high tensile steel (HTS) HT780 (JIS-SHY685)-welded joint containing an artificial semicircular slit on the weld toe were investigated. Three-point bending fatigue tests were conducted at a stress ratio of R = 0.05 for NP-treated welded specimens with and without a slit. The fatigue limits of all specimens increased by 9–200% due to the NP treatment. Furthermore, NP-treated specimens with slit depths of a = 1.0 mm exhibited high fatigue limits that were equal to those of NP-treated specimens without a slit. Therefore, a semicircular slit of less than a = 1.0 mm could be rendered harmless through NP treatment. This result indicates that the reliability of HTS-welded joints can be significantly improved via NP for surface defects with depths that are less than 1 mm, which are not detected through non-destructive inspection (NDI). Therefore, the problem regarding the reliability of HTS-welded joints that restricts the industrial utilization of HTS can be solved by performing both NDI and NP. The dominant factor that contributed to the improvement of the fatigue limit and increase in the acceptable defect size was the introduction of large and deep compressive residual stress with non-propagating cracks. View Full-Text
Keywords: welded joint; needle peening; compressive residual stress; surface defect; fatigue limit welded joint; needle peening; compressive residual stress; surface defect; fatigue limit
Figures

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
SciFeed

Share & Cite This Article

MDPI and ACS Style

Fueki, R.; Takahashi, K.; Handa, M. Fatigue Limit Improvement and Rendering Defects Harmless by Needle Peening for High Tensile Steel Welded Joint. Metals 2019, 9, 143.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Metals EISSN 2075-4701 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top