Fatigue behaviour of high frequency hammer peened ultra high strength steels

Berg, Jörn; Stranghöner, Natalie

doi:10.1016/j.ijfatigue.2015.08.012

Cited by 33 publications

(9 citation statements)

References 14 publications

(32 reference statements)

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“…FSP can be used as a new technique to increase fatigue strength of the fusion-welded joints, and provide advantages different from grinding [14] [15] [16] and remelting [17] [18] [19] for the weld geometry modification or peening [20] [21] [22] and post-weld heat treatment [23] for decreasing tensile residual stress. However, use of the FSP technique has been limited to a few light metal alloy welds so far.…”

Section: Introductionmentioning

confidence: 99%

Effects of Microstructural Modification Using Friction Stir Processing on Fatigue Strength of Butt-Welded Joints for High-Strength Steels

Yamamoto¹,

Ito²

2018

MSA

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Friction stir processing (FSP) is an effective surface-microstructure modification technique using a rotational tool to refine and homogenize microstructure of metallic materials. In this study, FSP was conducted on the surface of the heat-affected zone (HAZ), which is a region exhibiting degraded mechanical properties and shown to have microstructural changes, of butt-welded joints for two high-strength steels with tensile strength grades of 490 MPa and 780 MPa (hereafter HT490 and HT780, respectively). Inhomogeneous mixing of materials derived from weld metals and base metals (BMs) in a stir zone (SZ) produced inhomogeneous distribution of elements and microstructure depending on the set of the advancing side and retreating side in the SZs. The welded joints with FSP for HT490 exhibited higher hardness than that of the BM through whole of the SZ surface (fine polygonal ferrite grains and bainite structure with laths at the Mn-rich and Mn-poor regions, respectively). On the other hand, those for HT780 exhibited the minimum hardness value similar to that of the BM at the SZ surface (a few polygonal ferrite grains in the matrix of martensite laths). Fatigue strength increased by about 35 MPa and 15 MPa in stress amplitude at 10 7 cycles as fatigue limit due to FSP. Fatigue failure occurred at the BM and the SZ, respectively, in the welded joints modified by FSP for HT490 and HT780, in comparison with the HAZs in the as-welded joints for both grade steels. The difference in fatigue strength increase due to FSP and failure location between the welded joints for HT490 and HT780 can be attributed to the topmost SZ microstructures and their distribution.

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Section: Introductionmentioning

confidence: 99%

Effects of Microstructural Modification Using Friction Stir Processing on Fatigue Strength of Butt-Welded Joints for High-Strength Steels

Yamamoto¹,

Ito²

2018

MSA

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“…The compressive residual stresses created by the HFMI treatment of welds have rarely been investigated for steels with yield strength higher than 1000 MPa. In one case, Berg and Stranghöner [29] measured longitudinal and transverse compressive residual stresses close to 75% of the steels yield strength for a welded steel with a minimum yield strength of 1100 MPa after HFMI treatment.…”

Section: Effect Of Residual Stress On Fatigue Strengthmentioning

confidence: 92%

“…In a review paper by Jármai et al [45], up to 110% increase in fatigue strength has been reported for steels with yield strength higher than 900 MPa. It has also been discussed that the degree of improvement produced by HFMI treatment increases with steel yield strength [28,29,45]. For instance, Yildirim and Marquis [28], after assessing about 228 fatigue data points, proposed FAT 500 for welded steels with yield strength higher than 960…”

Section: Fatigue Strength Of Hfmi Treated Weldsmentioning

confidence: 99%

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Effect of high frequency mechanical impact treatment on fatigue strength of welded 1300 MPa yield strength steel

Harati

Svensson

Karlsson

et al. 2016

International Journal of Fatigue

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“…Various High-Frequency Hammer Peened (HFHP) ultra-high-strength steel (S960, S110 and S1300) joint types with different plate thicknesses were studied in (Berg & Stranghoner, 2016). They show the conservatism of existing design proposals.…”

Section: 3mentioning

confidence: 99%

Report of Committee III.2: Fatigue and fracture

2015

Ships and Offshore Structures XIX

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Fatigue behaviour of high frequency hammer peened ultra high strength steels

Cited by 33 publications

References 14 publications

Effects of Microstructural Modification Using Friction Stir Processing on Fatigue Strength of Butt-Welded Joints for High-Strength Steels

Effects of Microstructural Modification Using Friction Stir Processing on Fatigue Strength of Butt-Welded Joints for High-Strength Steels

Effect of high frequency mechanical impact treatment on fatigue strength of welded 1300 MPa yield strength steel

Report of Committee III.2: Fatigue and fracture

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