A through-process, thermomechanical model for predicting welding-induced microstructure evolution and post-weld high-temperature fatigue response

Ardghail, Padraig Mac; Harrison, Noel M.; Leen, Seán B.

doi:10.1016/j.ijfatigue.2018.02.015

Cited by 15 publications

(24 citation statements)

References 25 publications

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“…A previous paper by the authors [27] focused on the HTLCF performance of welded P91 specimens and demonstrated the capability of the present approach to predict weld life reduction. This paper presents a further development of the latter, as follows:…”

Section: Introductionmentioning

confidence: 83%

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A process-structure-property model for welding of 9Cr power plant components: The influence of welding process temperatures on in-service cyclic plasticity response

Ardghail

Harrison

Leen

2019

International Journal of Pressure Vessels and Piping

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A process-structure-property methodology is presented for welding of 9Cr steels under representative flexible operating conditions for a typical thermal power plant girth-welded pipe. The welding-induced evolution of microstructural variables is represented via (i) a solid-state phase transformation model for martensite-austenite transformation and (ii) empirical equations for prior austenite grain size, martensite lath width, hardness and M23C6 precipitate diameter and area fraction, calibrated from published heat treatment data.The temperature-dependent, physically-based, unified viscoplastic constitutive model, which includes a fatigue damage initiation criterion, is based on dislocation density evolution and is validated against high temperature cyclic plasticity data at a range of relevant temperatures for parent material P91, including combined isotropic-kinematic hardening effects. This model is shown to successfully predict weld-life reduction factor for cross-weld tests. The effects of key welding process variables on the microstructure gradient in the heat-affected zone, and associated thermo-mechanical, cyclic plasticity response are assessed. The inter-critical and fine-grained heat-affected zones are identified as the critical regions, consistent with observed plant experience. Increasing post-weld heat-treatment temperature from 760 o C from 780 o C is predicted to be detrimental due to increased precipitate coarsening. In contrast, increasing preheat and interpass temperature from 350 o C to 400 o C is predicted to be beneficial due to increased hardness in the critical regions.

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Section: Introductionmentioning

confidence: 83%

“…In the present approach, the naturally-occurring gradient in microstructure is represented. The authors have already presented the basis for this work [27] with application to uniaxial cross-weld test specimens.…”

Section: Introductionmentioning

confidence: 99%

A process-structure-property model for welding of 9Cr power plant components: The influence of welding process temperatures on in-service cyclic plasticity response

Ardghail

Harrison

Leen

2019

International Journal of Pressure Vessels and Piping

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“…Hence, a key next step for X100Q, is the application of this through-process methodology developed in the MECHANNICS project, e.g. see Mac Ardghail et al [6], to the present X100Q, specifically for the IF zone. This will facilitate more detailed analysis of the failure behaviour of the microstructure-gradient IF zones, which are so important for fatigue failure, as also demonstrated here.…”

Section: Discussionmentioning

confidence: 99%

“…This can perhaps be attributed to the more refined microstructure of this case shown in Figure 2 (c). However, this requires further investigation, for example, using the through-process modelling methodology [6] under development within the present Science Foundation Ireland (SFI) project "Multiscale, through-process characterisation for nextgeneration welded connections" (MECHANNNICS), in order to quantitatively assess the effects of the gradation in microstructure in the IF zone. Real joints will inevitably contain such IF regions also and, indeed, these are common locations of failure, which has motivated this work.…”

Section: Tensile Testingmentioning

confidence: 99%

Cyclic plasticity and low cycle fatigue damage characterisation of thermally simulated X100Q heat affected zone

et al. 2018

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Abstract. This paper presents the cyclic plasticity and low cycle fatigue (LCF) damage characterisation of thermally simulated heat affected zone (HAZ) for API 5L X100Q weldments. Microstructures representative of the HAZ for two cooling rates are generated using a Gleeble thermomechanical simulator for manufacture of strain-controlled cyclic plasticity test specimens. The simulated HAZ specimens are subjected to a strain controlled test programme which examines the cyclic effects of strain-range and the tensile response at room temperature. A modified version of the Chaboche rate independent plasticity model, which accounts for early stage damage is implemented to characterise the cyclic plasticity response, including isotropic and kinematic hardening effects. The constitutive parameters are fitted to experimental data using an optimisation procedure developed within a MATLAB code. The measured response of the simulated HAZ specimens is compared to that of the X100Q parent material (PM), and the simulated HAZ is shown to share the early stage fatigue damage behaviour of the PM, but exhibits significantly a higher yield and cyclic strength.

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“…For weld, Corigliano et al [44] investigated the behavior of welded T-joints under low-cycle fatigue though tests and nonlinear finite element analysis, which has contributed to the predicting model of fracture and fatigue behavior for welded joints. Some other studies [45][46][47][48][49][50] relating to the constitutive model of the different materials of a weld also should be mentioned, but the research on the cyclic constitutive model for the welding material of steel tubular truss structure joints has still not been fully carried out, and there is also a lack of model parameters that can reflect the damage deterioration of the welding material. Thus, the cumulative damage evolution rule [51][52][53][54][55] of welding materials also should be paid attention to.…”

Section: Introductionmentioning

confidence: 99%

Study on Hysteresis Model of Welding Material in Unstiffened Welded Joints of Steel Tubular Truss Structure

2018

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The weld form of intersecting joints in a steel tubular truss structure changes with the various intersecting curves. As the key role of joints in energy dissipation and seismic resistance, the weld is easy to damage, as a result the constitutive behavior of the weld is different from that of the base metal. In order to define the cumulative damage characteristic and study the constitutive behavior of welded metal with the influence of damage accumulation, low-cycle fatigue tests were carried out to evaluate overall response characteristics and to quantify variation of cyclic stress amplitude, unloading stiffness and energy dissipation capacity. The results show that the cyclic softening behavior of welding materials is apparent, however, the steel shows hardening behavior with the increase of cyclic cycles, while the cyclic stress amplitude, unloading stiffness, and energy dissipation capacity of the welding materials degenerate gradually. Based on the Ramberg–Osgood model and introducing the damage variable D, a hysteretic model of welding material with the effect of damage accumulation was established, including an initial loading curve, cyclic stress-strain curve, and hysteretic curve model. Further, the evolution equation of D was also built. The parameters reflecting the damage degradation were fitted by the test data, and the simulation results of the model were proved to be in good agreement with the test results.

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A through-process, thermomechanical model for predicting welding-induced microstructure evolution and post-weld high-temperature fatigue response

Cited by 15 publications

References 25 publications

A process-structure-property model for welding of 9Cr power plant components: The influence of welding process temperatures on in-service cyclic plasticity response

A process-structure-property model for welding of 9Cr power plant components: The influence of welding process temperatures on in-service cyclic plasticity response

Cyclic plasticity and low cycle fatigue damage characterisation of thermally simulated X100Q heat affected zone

Study on Hysteresis Model of Welding Material in Unstiffened Welded Joints of Steel Tubular Truss Structure

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