Study on Improvement Method of Fatigue Strength of Weld Joints by Hammer Peening on Base Metal

Nakanishi, Kenji; Morikage, Yasushi; Kawabata, Atsunori; Tomo, Hajime

doi:10.2208/jscejseee.71.10

Cited by 6 publications

(6 citation statements)

References 1 publication

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“…Therefore, the fatigue life of the out-of-plane gusset welded joint increased by more than 15 times after hammer peening. The fatigue life of specimens subjected to hammer peening in a previous study [ 27 ] also drastically increased, and it was observed that the fatigue strength of this detail was enhanced from class E to class A by hammer peening if assessed by S-N curves proposed by JCCS.…”

Section: Fatigue Life Assessed By Combined Measurements Of Dic and Xrdmentioning

confidence: 76%

“…The fatigue life of crack initiation ( N c ) and fatigue failure ( N f ) of the specimens AW and HP was assessed by S-N curves of typical fatigue details from Japan Society of Steel Construction (JSSC) [ 26 ] and shown in Figure 8 . The studied out-of-plane gusset welded joints corresponded to Class E in the design specification of JSSC, and the testing data from previous studies marked by triangular symbols were also added for reference [ 27 ].…”

Section: Fatigue Life Assessed By Combined Measurements Of Dic and Xrdmentioning

confidence: 99%

“…The fatigue life of crack initiation accounted for approximately 39% of that of the fatigue failure. The data points from the reference [ 27 ] were also roughly scattered on the design curve of Class E.…”

Section: Fatigue Life Assessed By Combined Measurements Of Dic and Xrdmentioning

confidence: 99%

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Fatigue Life Assessment of Welded Joints by Combined Measurements Using DIC and XRD

Wang

Ueda

Ryota³

et al. 2021

Materials

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The existing methods of assessing the fatigue life of welded joints fail to consider local strain ranges and mean stress at the weld toe. The present work proposes a novel approach to assessing the fatigue life of welded joints by conducting measurements with digital image correlation (DIC) and X-ray diffraction (XRD) in combination. Local strain ranges at the weld toe of gusset welded joints were measured by DIC. Hammer peening was conducted on the welded joints to introduce different initial stresses. The influence of mean stress was investigated by considering initial residual stress measured by XRD and a perfect plastic material model. The fatigue experiment was carried out on specimens with and without hammer peening. The results showed that hammer peening could offset adverse welding deformation effectively, and introduce significant residual compressive stress. The fatigue failure life increased by more than 15 times due to hammer peening. The fatigue initiation life assessed by the proposed method was close to that based on nominal stress, indicating that the proposed method is reliable for predicting the fatigue initiation life of welded joints.

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Section: Fatigue Life Assessed By Combined Measurements Of Dic and Xrdmentioning

confidence: 76%

Section: Fatigue Life Assessed By Combined Measurements Of Dic and Xrdmentioning

confidence: 99%

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Fatigue Life Assessment of Welded Joints by Combined Measurements Using DIC and XRD

Wang

Ueda

Ryota³

et al. 2021

Materials

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“…This is likely the case because the high yield stress of high-tensile-strength steel requires substantial energy for plastic deformation by BMHIP. According to [5], the BMHIP air tool, which is machined so that the flat part of the tool tip has a roundness (R) value of 1-3 mm square and the edge becomes 0.5 mm, as shown in Figure 2, is hit while being pressed perpendicularly to the test body base material. The speed of the BMHIP treatment is about 5 cm/min, the air pressure of the air tool is 0.63 MPa, and the frequency at which the air tool is applied to the object is about 90 Hz.…”

Section: Specimens and Test Conditionsmentioning

confidence: 99%

“…In this study, we used a technique for improving fatigue strength by base metal hammer impact peening (BMHIP). A previous study [5] clarified the relationship between the surface residual stress due to BMHIP, the number of impacts, and the effect of improving fatigue strength for ordinary steel (490 MPa grade steel).…”

Section: Introductionmentioning

confidence: 99%

Investigation on Residual Compressive Distribution of High-Strength Steel for Bridges by Base Metal Hammer Impact Peening

Kurihara¹,

Sakino

Kato

2021

Applied Mechanics

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Various peening techniques have been used to improve the fatigue strength of steel structures. Among them, base metal impact hammer peening shows significant improvement in fatigue strength in ordinary steel, but the effect on high-strength steel has not been sufficiently studied. Accordingly, this study applied base material hammer impact peening to test specimens of 780 MPa grade high-strength steel (HT780) and 490 MPa grade ordinary steel (SM490), and the residual stress was measured and simulated. The experimental results clarified that a large compressive residual stress was introduced into the inner part of the plate thickness near the indentation in the high-strength steel, although the range of introduction of residual stress was equivalent in both the ordinary steel and high-strength steel.

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09.06: Continuous fatigue test of welded joint taken from SBHS700 girder specimen

2017

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Steels for bridge high performance structures (SBHS) have high strength, good weldability and workability. SBHS700 of 780MPa class must particularly clarify with respect to fatigue problems. At the previous study, the fatigue test with the SBHS700 girder specimen was carried out and fatigue strength improvement methods to introduce compressive residual stress were used on its out of plane gusset welded joints. However, the previous study did not quantitatively show the fatigue strength improvement because these out of plane gussets have not failed. In this study, in order to clarify the effects of the fatigue strength improvement methods, these out of plane gussets are taken from the girder by gas fusion cutting and made as small fatigue specimens. If there is enough compressive residual stress left at the weld toe, the fatigue tests are carried out. Before the fatigue tests, residual stress at 2mm from treatment edge of centre gusset was measured by the X-ray diffraction method and compared with previous studies. The target of fatigue test was UIT (Ultrasonic impact treatment). At first, nominal stress range is 100MPa under the same condition of the previous study. If fatigue crack does not appear after 2 million cycles, nominal stress range is increased, such as 150MPa, 180MPa, 200MPa. As a result, enough compressive residual stress was confirmed at the weld toe from the X-ray diffraction method. UIT specimens reached 2 million cycles in 200MPa stress range. Fatigue test results were considered based on an equation which modified Goodman's diagram applies to the weld toe due to estimate the fatigue limit. Therefore, high fatigue strength can be expected.

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Study on Improvement Method of Fatigue Strength of Weld Joints by Hammer Peening on Base Metal

Cited by 6 publications

References 1 publication

Fatigue Life Assessment of Welded Joints by Combined Measurements Using DIC and XRD

Fatigue Life Assessment of Welded Joints by Combined Measurements Using DIC and XRD

Investigation on Residual Compressive Distribution of High-Strength Steel for Bridges by Base Metal Hammer Impact Peening

09.06: Continuous fatigue test of welded joint taken from SBHS700 girder specimen

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