Session: DA-08-01 Fitness for Service Evaluations-1

Paper Number: 153445

153445 - Synergistic Utilisation of Informatics and Data Centric Integrity Engineering (Sindri) 

Abstract: 

Mechanical behaviour of engineering alloys is dependent upon their chemistry and the underlying microstructure both affected by processing and heat-treatment. In traditional mechanics the microstructural dependence is generally simplified by introducing laws that govern the behaviour of continuum solids and adjust their parameters according to the average properties of the microstructure.  This approach has served industrial applications well in most applications, however in high value and safety sensitive components where seemingly negligible changes to the microstructure can significantly alter the outcome of a safety assessment analysis. For example, small changes in the welding parameters used in manufacturing a steam generator can affect the texture of the weld, thus influencing its hardening behaviour and residual stress profile which in turn decide the safe usage of the steam generator by years [1]. For this reason, detailed experimental characterisation techniques combined with microstructural simulations have been developed in the recent decades which can explain and predict the behaviour of materials at small length scales with precision [2]. The downfall, however, has been the translation of these computationally expensive models and limited success in performing detailed characterisation on statistically representative volumes of material complemented with robust multi-scale modelling that can predict the behaviour of an industrial scale component. 

SINDRI is a project which aims to tackle this issue. It employs the recent advances in high-throughput characterisation technique such as high angular resolution electron back-scatter diffraction and laser beam milling with state of the art modelling. The high fidelity characterisation data informs computationally expensive microstructural simulation techniques (e.g. crystal plasticity finite element modelling), which are then parallelised to allow for their uncertainty quantification using machine learning algorithms (e.g. Gaussian Process) and broader surrogate modelling approaches. The results are a route to probabilistic models that can capture the variation in the mechanical behaviour of material informed by the statistical distribution of key features within its microstructure. 

This paper provides a case study of this approach focusing on creep fatigue deformation of stainless steel 316H at 550^oC. The variability of the cyclic – dwell response of the material to changes in its microstructural texture is quantified. The texture variation within a weldment has been extracted from large scale EBSD informing the model which is validated via HR-DIC and HR-EBSD. Gaussian Process is used to estimate the variability in the response of the material as a result of texture change. An engineering assessment code is then used to convert the variability in creep-well response to uncertainty in the safe lifetime of the weldment. The results show that small changes in material sometimes ignored by practicing engineers can have a profound effect on lifetime calculation while providing some possible scientific base for a microstructurally informed probabilistic integrity assessment framework in the future.  

 

[1] Kai-Shang Li, Run-Zi Wang, Le Xu, Cheng-Cheng Zhang, Xian-Xi Xia, Min-Jin Tang, Guo-Dong Zhang, Xian-Cheng Zhang, Shan-Tung Tu, Life prediction and damage analysis of creep-fatigue combined with high-low cycle loading by using a crystal plasticity-based approach, International Journal of Fatigue, Volume 164, 2022, 107154

[2] Farhan Ashraf, Ranggi S. Ramadhan, Abdullah Al Mamun, James A.D. Ball, Eralp Demir, Thomas Connolley, David M. Collins, Mahmoud Mostafavi, David Knowles, Investigating grain-resolved evolution of lattice strains during plasticity and creep using 3DXRD and crystal plasticity modelling, Acta Materialia, Volume 278, 2024, 120250

Presenting Author: David Knowles Henry Royce Institute

Presenting Author Biography: David Knowles is the Royce CEO and a Professor in Materials Engineering. He is a specialist in material structural integrity of materials from extended roles in industry and academia covering sectors including nuclear, renewables, oil and gas, aerospace and transport. He has held academic roles at Universities of Cambridge and Bristol and worked across Asia, Europe and the UK, with both SMEs and large companies including Shell and Atkins.

Authors:

Hugh Dorward University of Bristol
Maria Yanova University of Manchester
Mike Smith The University of Manchester
Anastasia Vasileiou Anastasia Vasileiou
Chris Truman University of Bristol
Matthew Peel University of Bristol
Mahmoud Mostafavi Monash University
David Knowles Henry Royce Institute