Fatigue strength modelling of high-performing welded joints

Remes, Heikki; Gallo, Pasquale; Jelovica, Jasmin; Romanoff, Jani; Lehto, Pauli

doi:10.1016/j.ijfatigue.2020.105555

Cited by 42 publications

(30 citation statements)

References 45 publications

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“…It is worth underlining that the weldments under consideration have a higher strength with respect to those realised with common welding techniques, 46 leading to the need of a different fatigue curve for this kind of weldments with respect to those considered by the standards 46 . The higher fatigue performance of these weldments becomes clear by comparing the NSIF‐based fatigue strength at 5 · 10 6 cycles of welded joints made of structural steels, 10,27 and equal to

{normalΔ K}_{th} = 180 MPa \sqrt{mm}

, with that evaluated for the specimens under consideration, 1 and equal to

{normalΔ K}_{th} = 215 MPa \sqrt{mm}

.…”

Section: Resultsmentioning

confidence: 99%

“…The use of the control volume radius, usually adopted dealing with common steel welded joints, 39 has been proved to be inadequate for assessing the fatigue properties of high‐performing welded joints 46 . The adopted control volume radius is equal to R 0 = 0.2 mm that results to be optimal in describing the higher fatigue performance of these weldments.…”

Section: Resultsmentioning

confidence: 99%

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Fatigue assessment of high strength welded joints through the strain energy density method

Foti

Berto

2020

Fatigue Fract Eng Mat Struct

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The main aim of the present work is to investigate, through the strain energy density method, the fatigue behaviour of high strength welded joints realised employed in hydraulic runner blades. The geometries, found in literature, present the welding bead machined in order to have no geometrical discontinuities in the specimen realising a wide fitting radius between the two welded plates; the only critical geometrical discontinuity in the specimen is given by the lack of penetration that leads to an internal crack-like defect. The specimens presented failure both from the weld toe and from the weld root depending on the amount of welding penetration. The results, summarised in this work with the strain energy density method, show clearly the possibility to consider a unique master curve for this kind of joints regardless of the failure initiation point. Acquiring, through a finite element model, the strain energy density value both at the weld toe and at the weld root and comparing them, the method is proved to be adequate to detect the most critical area of the joint. A first fatigue master curve in terms of cyclic averaged strain energy density value is provided for the fatigue design of high strength welded joints.

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{normalΔ K}_{th} = 180 MPa \sqrt{mm}

, with that evaluated for the specimens under consideration, 1 and equal to

{normalΔ K}_{th} = 215 MPa \sqrt{mm}

.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Fatigue assessment of high strength welded joints through the strain energy density method

Foti

Berto

2020

Fatigue Fract Eng Mat Struct

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“…One of the most widely accepted models for fatigue analysis is the Paris' law [23], which offers a correlation between the linear elastic fracture mechanics (LEFM) and the fatigue crack propagation. The Paris' law relates the fatigue crack propagation length (a) per cycle to the variation range (ΔK) of the stress intensity factor during cyclic loading [24][25][26]. Thus, the Paris' law is employed here to describe the fatigue crack propagation characteristic.…”

Section: Methodsmentioning

confidence: 99%

Inhomogeneous microstructure and fatigue crack propagation of thick-section high strength steel joint welded using double-sided hybrid fiber laser-arc welding

Feng

Chen

et al. 2021

Optics & Laser Technology

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“…For instance, sustainability in the maritime sector requires the effective use of high-strength steels in the large welded structures. In combination with new structural topologies, the weight of cruise ships can be reduced considerably [1,2]. The limiting factor of higher strength materials is their sensitivity to defects induced in the manufacturing process.…”

Section: Introductionmentioning

confidence: 99%

“…the cutting and welding processes need to be optimised for the new steel grades. Results have shown that by using high-quality manufacturing, the load carrying capacity of high-strength steels can be significantly higher compared to conventional steels and to considerably exceed the design values set by classification society guidelines [2][3][4][5]. A fundamental aspect is understanding how the material properties change during the manufacturing process and discovering the underlying microstructural characteristics that explain these changes.…”

Section: Introductionmentioning

confidence: 99%

EBSD characterisation of grain size distribution and grain sub-structures for ferritic steel weld metals

Lehto

Remes

2022

Weld World

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Microstructural characterisation of engineering materials is required for understanding the relationships between microstructure and mechanical properties. Conventionally grain size is measured from grain boundary maps obtained using optical or electron microscopy. This paper implements EBSD-based linear intercept measurement of spatial grain size variation for ferritic steel weld metals, making analysis flexible and robust. While grain size has been shown to correlate with the strength of the material according to the Hall–Petch relationship, similar grain sizes in weld metals with different phase volume fractions can have significantly different mechanical properties. Furthermore, the solidification of the weld pool induces the formation of grain sub-structures that can alter mechanical properties. The recently developed domain misorientation approach is used in this study to provide a more comprehensive characterisation of the grain sub-structures for ferritic steel weld metals. The studied weld metals consist of varying mixtures of primary ferrite, acicular ferrite, and bainite/martensite, with large differences observed in hardness, grain size, grain morphology, and dislocation cell size. For the studied weld metals, the average dislocation cell size varied between 0.68 and 1.41 µm, with bainitic/martensitic weld metals showing the smallest sub-structures and primary ferrite the largest. In contrast, the volume-weighted average grain size was largest for the bainitic/martensitic weld metal. Results indicate that a Hall–Petch-type relationship exists between hardness and average dislocation cell size and that it partially corrects the significantly different grain size—hardness relationship observed for ferritic and bainitic/martensitic weld metals. The methods and datasets are provided as open access.

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Fatigue strength modelling of high-performing welded joints

Cited by 42 publications

References 45 publications

Fatigue assessment of high strength welded joints through the strain energy density method

Fatigue assessment of high strength welded joints through the strain energy density method

Inhomogeneous microstructure and fatigue crack propagation of thick-section high strength steel joint welded using double-sided hybrid fiber laser-arc welding

EBSD characterisation of grain size distribution and grain sub-structures for ferritic steel weld metals

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