Asymptotic residual stress distribution induced by multipass welding processes

Ferro, Paolo; Berto, Filippo; James, Neil

doi:10.1016/j.ijfatigue.2016.11.022

Cited by 33 publications

(17 citation statements)

References 47 publications

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“…On the other hand, additive technologies, such as WAAM or wire laser metal deposition (LMD-W), can also be modelled by a Finite Element (FE) method based on the element-birth technique, for the determination of real temperature fields and residual stresses. The focus for this simulation of the WAAM process has been on calculating temperature distribution, displacement of components and residual stresses [11][12][13][14][15][16]. The focus of this paper is not on powder-bed methods.…”

Section: Introductionmentioning

confidence: 99%

Thermo-Mechanical Modelling of Wire-Arc Additive Manufacturing (WAAM) of Semi-Finished Products

Graf

Hälsig

Höfer

et al. 2018

Metals

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Additive manufacturing processes have been investigated for some years, and are commonly used industrially in the field of plastics for small- and medium-sized series. The use of metallic deposition material has been intensively studied on the laboratory scale, but the numerical prediction is not yet state of the art. This paper examines numerical approaches for predicting temperature fields, distortions, and mechanical properties using the Finite Element (FE) software MSC Marc. For process mapping, the filler materials G4Si1 (1.5130) for steel, and AZ31 for magnesium, were first characterized in terms of thermo-physical and thermo-mechanical properties with process-relevant cast microstructure. These material parameters are necessary for a detailed thermo-mechanical coupled Finite Element Method (FEM). The focus of the investigations was on the numerical analysis of the influence of the wire feed (2.5–5.0 m/min) and the weld path orientation (unidirectional or continuous) on the temperature evolution for multi-layered walls of miscellaneous materials. For the calibration of the numerical model, the real welding experiments were carried out using the gas-metal arc-welding process—cold metal transfer (CMT) technology. A uniform wall geometry can be produced with a continuous welding path, because a more homogeneous temperature distribution results.

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Section: Introductionmentioning

confidence: 99%

Thermo-Mechanical Modelling of Wire-Arc Additive Manufacturing (WAAM) of Semi-Finished Products

Graf

Hälsig

Höfer

et al. 2018

Metals

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“…Residual stresses substantially change the stress–strain fields in the cracked region and can also induce fractures in the contact surfaces during cyclic loading, which is similar to the other contact mechanisms. Ritchie and Suresh have classified these contact mechanisms in which the deformation at the crack tip decreases as zone and contact shielding mechanisms.…”

Section: Introductionmentioning

confidence: 96%

Crack closure in friction stir weldment using non‐linear model for fatigue crack propagation

Lepore

Maligno

Berto³

2019

Fatigue Fract Eng Mat Struct

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The fatigue crack propagation in a friction stir‐welded sample has been simulated herein by means of two 3‐dimensional finite element method (FEM)‐based analyses. Numerical simulations of the fatigue crack propagation have been carried out by assuming a residual stress field as a starting condition. Two initial cracks, observed in the real specimen, have been assessed experimentally by performing fatigue tests on the welded sample. Hence, the same cracks have been placed in the corresponding FE model, and then a remote load with boundary conditions has been applied on the welded specimen. The material behaviour of the welded joint has been modelled by means of the Ramberg‐Osgood equation, while the non‐linear Kujawski‐Ellyin (KE) model has been adopted for the fatigue crack propagation under small‐scale yielding (SSY) conditions. Owing to the compressive nature of the residual stress field that acts on a part of the cracked regions, the crack closure phenomenon has also been considered. Then, the original version of the KE law has been modified to fully include the closure effect in the analysis. Later, the crack closure effect has also been assessed in the simulation of fatigue propagation of three cracks. Finally, an investigation of the fracture process zone (FPZ) extension as well as the cyclic plastic zone (CPZ) and monotonic plastic zone (MPZ) extensions have been assessed.

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“…With the characteristics of high strength and excellent weldability, high-strength low-alloy steel is widely used in automobiles, railway vehicles, bridges and other industries [1,2]. In the process of welding steel, it is easy to generate large and centralized residual stresses, which may produce stress corrosion cracking and brittle fracture, seriously reduce the anti-fatigue performance, and greatly reduce the service life of the components [3][4][5][6]. The mechanical and heat treatment methods are usually used to reduce or eliminate the welding residual stress.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Martensitic Phase Transformation Dilation on Microstructure, Strain–Stress and Mechanical Properties for Welding of High-Strength Steel

et al. 2018

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The application of low transformation temperature (LTT) wire can effectively reduce residual stress, without the need for preheating before welding and heat treatment after welding. The mechanism reduces the martensitic transformation temperature, allowing the martensite volume expansion to offset some or all of the heat-shrinking, resulting in reduced residual stress during the welding process. In this paper, commercial ER110S-G welding wire and LTT wire with chemical composition Cr10Ni8MnMoCuTiVB were developed to solve the problem of stress concentration. The microstructure of the LTT joint is mainly composed of martensite and a small amount of residual austenite, while the microstructure of the ER110S-G joint is mainly composed of ferrite and a small amount of granular bainite. The micro-hardness and tensile strength of the LTT joint is higher than that of ER110S-G joint; however, the impact toughness of the LTT joint is not as good as that of the ER110S-G joint. The martensitic phase transformation of LTT starts at 212 • C and finishes at around 50 • C, and the expansion caused by phase transition is about 0.48%, which is much higher than that of the base metal (0.15%) and ER110S-G (0.18%). The residual tensile stress at the weld zone of the ER110S-G joint is 175.5 MPa, while the residual compressive stress at the weld zone of LTT joint is −257.6 MPa.2 of 15 reduced tensile residual stress during welding process. This not only reduces the production cost, but also improves the fatigue resistance of the welded components [9].Dai et al.[10] used the traditional commercial OK75.78 wire and the low transformation temperature (LTT) wire to weld two comparable Weldox960 base plates. The residual stress of the joints were measured using neutron diffraction, with the results showing that LTT can effectively reduce the welding residual stress of high-strength steel welding and improve the stress distribution. Chiaki and Shiga [11] found that the residual stress distribution is ideal when the starting temperature of martensite transformation is 200 • C, and the residual compressive stress at the weld toe is 300 MPa.Ohta et al. [12] found that by using the 10 Cr-10 Ni-0.7 Mn wire the fatigue limit of the LTT joint could be twice that of conventional joints. Barsoum et al. [13] studied the effect of residual stress on fatigue strength. Fatigue tests showed that the LTT joint had a 40% increase in fatigue strength compared to conventional joints. Fabrice et al. [14] found that the LTT wire significantly improved the fatigue strength of the joint, and the fatigue strength was 60% higher than that of the conventional wire (G3Si1) filling joint in two million cycles. Wang et al.[15] compared the conventional wire of C-Mn and LTT wire of 9.1 Cr-8.5 Ni-1.25 Mn, and showed that the fatigue strength was improved by 59% when using LTT wire. Altenkirch et al.[16] simulated the stress state of the welded structure during service and analyzed the changes in its organization and performance. The results showed that the low transfor...

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Asymptotic residual stress distribution induced by multipass welding processes

Cited by 33 publications

References 47 publications

Thermo-Mechanical Modelling of Wire-Arc Additive Manufacturing (WAAM) of Semi-Finished Products

Thermo-Mechanical Modelling of Wire-Arc Additive Manufacturing (WAAM) of Semi-Finished Products

Crack closure in friction stir weldment using non‐linear model for fatigue crack propagation

The Effect of Martensitic Phase Transformation Dilation on Microstructure, Strain–Stress and Mechanical Properties for Welding of High-Strength Steel

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