An Integrated Model to Predict Microstructure and Mechanical Properties in the Heat Affected Zone for X80 Linepipe

Poole, Warren J.; Militzer, Matthias; Garcin, Thomas

doi:10.1115/ipc2012-90337

Cited by 2 publications

(1 citation statement)

References 5 publications

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“…The literature offers several approaches to modelling weld microstructures numerically, considering specific simplifying assumptions about grain geometry or orientation [14][15][16][17][18]. The finite element analysis (FEA) is suitable for solving various problems in solid mechanics, heat transport and other physical domains.…”

Section: Introductionmentioning

confidence: 99%

Supporting Imaging of Austenitic Welds with Finite Element Welding Simulation—Which Parameters Matter?

et al. 2023

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The basic principle of ultrasound is to relate the time of flight of a received echo to the location of a reflector, assuming a known and constant velocity of sound. This assumption breaks down in austenitic welds, in which a microstructure with large oriented austenitic grains induces local velocity differences resulting in deviations of the ultrasonic beam. The inspection problem is further complicated by scattering at grain boundaries, which introduces structural noise and attenuation. Embedding material information into imaging algorithms usually improves image quality and aids interpretation. Imaging algorithms can take the weld structure into account if it is known. The usual way to obtain such information is by metallurgical analysis of slices of a representative mock-up fabricated using the same materials and welding procedures as in the actual component. A non-destructive alternative to predict the weld structure is based on the record of the welding procedure, using either phenomenological models or the finite element method. The latter requires detailed modelling of the welding process to capture the weld pool and the microstructure formation. Several parameters are at play, and uncertainties intrinsically affect the process owing to the limited information available. This paper reports a case study aiming to determine the most critical parameters and levels of complexity of the weld formation models from the perspective of ultrasonic imaging. By combining state-of-the-art welding simulation with time-domain finite element prediction of ultrasound in complex welds, we assess the impact of the modelling choices on the offset and spatial spreading of defect signatures. The novelty of this work is in linking welding simulation with ultrasonic imaging and quantifying the effect of the common assumptions in solidification modelling from the non-destructive examination perspective. Both aspects have not been explored in the literature to date since solidification modelling has not been used to support ultrasonic inspection extensively. The results suggest that capturing electrode tilt, welding power, and weld path correctly is less significant. Bead shape was identified as having the greatest influence on delay laws used to compute ultrasonic images. Most importantly, we show that neglecting mechanical deformation in FE, allowing for simpler thermal simulation supplemented with a phenomenological grain growth loop, does not reduce the quality of the images considerably. Our results offer a pragmatic balance between the complexity of the model and the quality of ultrasonic images and suggest a perspective on how weld formation modelling may serve inspections and guide pragmatic implementation.

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Section: Introductionmentioning

confidence: 99%

Supporting Imaging of Austenitic Welds with Finite Element Welding Simulation—Which Parameters Matter?

et al. 2023

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The Effect of Niobium on Austenite Decomposition in Line Pipe Steels

Robinson

Garcin

Poole

et al. 2016

Volume 3: Operations, Monitoring and Maintenance; Materials and Joining

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Niobium is a common micro-alloying addition in high-strength low-alloy (HSLA) steels primarily to add strength to the final product. Detailed quantification of the various effects of niobium is critical for understanding the microstructure evolution in the heat affected zone (HAZ) of welds. Laser ultrasonics for metallurgy (LUMet) was used to measure austenite grain growth kinetics in two experimental HSLA steels during continuous heating. For higher heating rates that are of relevance for the HAZ, grain growth during heating is negligible and grain size is determined during the brief time at the peak temperature. Thermal histories were designed based on these tests to produce a variety of microstructures relevant for various positions in the HAZ i.e. coarse and fine grain regions. It was found that the dissolution of niobium carbonitrides has a strong effect on austenite decomposition, particularily in the case of large austenite grain sizes. Nb in solution significantly depresses transformation temperatures in refinement of bainitic microstructures, significantly increasing the hardness in the coarse grained HAZ.

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An Integrated Model to Predict Microstructure and Mechanical Properties in the Heat Affected Zone for X80 Linepipe

Cited by 2 publications

References 5 publications

Supporting Imaging of Austenitic Welds with Finite Element Welding Simulation—Which Parameters Matter?

Supporting Imaging of Austenitic Welds with Finite Element Welding Simulation—Which Parameters Matter?

The Effect of Niobium on Austenite Decomposition in Line Pipe Steels

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