Fatigue Limit Improvement and Rendering Defects Harmless by Needle Peening for High Tensile Steel Welded Joint
Autor: | Koji Takahashi, Ryutaro Fueki, Mitsuru Handa |
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Jazyk: | angličtina |
Rok vydání: | 2019 |
Předmět: |
lcsh:TN1-997
Materials science 0211 other engineering and technologies 02 engineering and technology Welding law.invention needle peening surface defect 0203 mechanical engineering Residual stress law 021105 building & construction Ultimate tensile strength General Materials Science welded joint Composite material lcsh:Mining engineering. Metallurgy Metals and Alloys Bending fatigue technology industry and agriculture Peening Dominant factor compressive residual stress respiratory system Fatigue limit Slit fatigue limit 020303 mechanical engineering & transports sense organs |
Zdroj: | Metals Volume 9 Issue 2 Metals, Vol 9, Iss 2, p 143 (2019) |
ISSN: | 2075-4701 |
DOI: | 10.3390/met9020143 |
Popis: | 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&ndash 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. |
Databáze: | OpenAIRE |
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