An integrated (ICME) approach to multiscale modelling of the fabrication and joining of powder processed parts

Lead Research Organisation: University of Birmingham
Department Name: Metallurgy and Materials

Abstract

The applicability of metallic powder based production methods such as HIP or additive layer manufacturing (ALM) are restricted by an inability to define the process parameters with sufficient accuracy to provide the quality required for industrial production. Similarly the implementation of the joining technologies needed for component fabrication is limited by a lack of understanding of both the gas-liquid phase interactions and the effect of the solid state phase transformations that occur in the relevant alloy systems. Traditional solutions, based on practical trials and physical assessment, are both costly and time consuming and for the long service lives encountered in the energy and propulsion industries are not feasible while empirically based phenomenological modelling approaches cannot provide the required fidelity.
To address these industrial needs a multiscale modelling approach is proposed which combines experimental validation with the application of materials modelling, at the short length scales required to capture the relevant physics, together with the development of techniques to incorporate the predicted behaviour in a consistent manner at higher length scales for application to component level simulations.
The multiscale model integration will consist of a number of component parts commencing with new multiphysics based computational fluid dynamics calculations of the short length scale fluid flow and liquid/gas interactions in welding and additive manufacturing. These will provide data on porosity formation which will be combined with cellular automata predictions of grain structure. Novel methods will be developed to combine this fine scale data in a finite element based crystal plasticity framework to define representative volume elements for modelling the macroscopic behaviour in component stress analysis.
The component level simulation work will build upon the EPSRC Manufacturing Fellowship of Prof Smith on a whole-life approach to high integrity welding technologies by utilising the knowledge gained on the effect of the microstructural changes imposed by welding. These have a profound influence on a weld's resistance to in-service degradation and upon its sensitivity to the presence of cracking. The microstructural characterisation data available on 316L stainess steel from the Fellowship work will also provide a basis for the model validation.
A key part of the developments in this project will be the extension, from typical single value deterministic models, to statistically based descriptions of material properties and process variability. This is a challenging activity but it is essential that modelling tools become capable of predicting the scatter that is seen in real materials. A successful solution will not only generate novel science but will clearly lead to the development of probabilistic lifing methods with risk based outputs for decision making which have clear benefits for industry. This approach provides the prospect of a better understanding of in-service performance of components and welds in both the existing UK nuclear reactor fleet and in any industrial sector where long term structural performance is important.
Similar developments in the US have led to a new field known as Integrated Computational Materials Engineering (ICME). This is a multi-disciplinary approach to product design that offers huge economic potential and the successful implementation of ICME will revolutionise the way components are being designed and manufactured. This proposal will address the modelling and design challenge using an ICME based approach on industrial demonstrators of 316L stainless steel HIPped and TIG welded parts. The demonstrators, supplied by the partners from the aerospace and energy industries, will show the benefits that can be achieved in different market sectors. The proposed programme will be the first attempt in the UK to use ICME tools on large industrial scale demonstrators.

Planned Impact

The novel modelling technologies proposed will provide a scientific breakthrough in terms of modelling capability and the application of multiscale approaches. The impact on the multi-scale modelling academic community, of the developments of the modelling tools and the mechanistic understanding through characterisation, will be significant as it will facilitate the scientific understanding of the manufacturing processes studied The development of the statistical and stochastic modelling approaches, will offer a considerable advantage to the academic materials science community in allowing the prediction of distributions of behaviour rather than conventional deterministic solutions. In addition, the further validation of this capability will allow the design engineers within the energy and aerospace industries to have an improved tool for life prediction. It is anticipated that the software integration requirements of ICME and the ability to analyse large volumes of data will also lead to advances in mathematics and computer science. Although the targeted demonstrators are aimed at specific industrial application the approaches used will also be of generic value to other manufacturing methods and materials.
The project will positively impact on manufacturing industry in the energy and aerospace sectors through the use and implementation of the ICME tools by both original equipment manufacturers (OEMs) and their supply chain. Initial exploitation of ICME is in the aerospace sector and the UK has a 17% global market share in aerospace industry revenues making it the largest in Europe and second to the US worldwide. In 2012, the industry had a turnover of some £20 billion and consequently the financial impact of ICME is potentially highly significant. It has been shown (G. Goldbeck, The economic impact of molecular modelling of chemicals and materials. Goldbeck Consulting Report, 2012) that "There is strong evidence that the integration of materials modelling with engineering workflows (so called Integrated Computational Materials Engineering) has been carried through successfully with a large return on investment (ROI)." (where ROI is the ratio between revenue generated from products resulting from a project in which materials modelling was used and the investment in materials modelling). The returns associated with modelling implementation have been reported to range from 2 to 20 thus justifying an expectation of benefits in excess of 5:1
The adoption of ICME methods can result in significant business benefits, for example, Rolls-Royce have achieved reductions in casting scrap (in excess of US$5M p.a.) and reduced (by 90%) the number of forming trials required for hot isostatic pressing (HIP) developments thus shortening the time to market of new products. As a consequence to maintain competitive advantage, Rolls-Royce is fully committed to continually extend the use of Materials and Process Modelling within its business. For solidification processes and powder joining, successful demonstration of modelling capabilities will lead to high technology readiness research and demonstration of component scale feasibility, particularly in the Energy and Aerospace fields. The ultimate exploitation will lead to far fewer large scale tests and trials and enhanced component capabilities. This will subsequently encourage future research to push scientific understanding further still.
Additional benefits to the UK economy will be achieved through the increased adoption of ICME giving rise to reduced time to market, lower costs and improved competitiveness. The initial applications of ICME will be focussed on the energy and aerospace sectors and this will contribute to societal benefits resulting from cleaner energy generation and more efficient transport solutions.
 
Description A theoretical approach has been developed for the prediction of high temperature properties (tensile and fatigue) of steels in terms of the material microstructure. The approach has been used to determine key parameters (kinematic back stresses) for component level modelling of the flow stress behaviour.
Exploitation Route The tools CA-FD model for grain growth and dendritic predictions as well as the crystal plasticity model are being exploited by industrial partner (Rolls-Royce). Furthermore, computational approach developed so far enables to study causal link between process-induced microstructures and properties. This computation tools developed in this work can be exploited (and are currently being used) in other manufacturing processes such as additive manufacture as well as in the development of process monitoring approaches.
Sectors Aerospace, Defence and Marine,Energy

URL https://doi.org/10.21820/23987073.2018.5.65
 
Description The outputs from this project have been used to improve the additive manufacturing modelling capability in Rolls-Royce. The microstructure and crystal plasticity models development funded within this programme has led to further funding from Dstl in areas of additive manufacture and fatigue.
First Year Of Impact 2018
Sector Aerospace, Defence and Marine
Impact Types Economic

 
Description Contibutor to the NASA 2040 Vision for ICME
Geographic Reach North America 
Policy Influence Type Participation in a advisory committee
 
Title Local compositionally linked cellular automata model for dendrite and grain size prediction in welding 
Description A cellular automata based model has been developed which uses local compositional effects linked to a Thermocalc database to provide more accurate predictions of dendrite and grain size development during solidification. 
Type Of Material Improvements to research infrastructure 
Year Produced 2018 
Provided To Others? No  
Impact This has allowed the solidification model to be linked with finite elements calculations to allow industrially acceptable run times when compared with phase field alternatives. 
 
Title Multi-phase flows 
Description A computational approach for handling multiphase flows has been developed within the project. The approach is based on a volume -of-fluids formulation. It treats the phase transitions induced by a high energy density source. The framework also accounts for diffusion of chemical species. The C++ code developed is based on the open source software OpenFOAM. 
Type Of Material Improvements to research infrastructure 
Year Produced 2020 
Provided To Others? Yes  
Impact The approach has been used to simulate the development of metal liquid melt pools during laser fusion welding of austenitic steels and titanium as well as during SLM of nickel-based superalloys. It has also been used to provide realistic thermal fields for the prediction of solidification structures using the CA-FD code developed within the programme. 
 
Title Physics-based crystal plasticity for stainless steels 
Description A physics-based crystal plasticity (CP) finite element (FE) approach has been developed for the prediction of flow stress behaviour of austenitic steels. The mathematical framework accounts for key metallurgy of these class of alloys such as grain size distributions, nobilities and dislocation structure parameters (such jogs, statistically stored dislocations (SSDs) and geometrically stored dislocations (GNDs)). The theory developed identifies the forms of the kinematic back stress arising from two sources of heterogeneous dislocation slip: slip bands and between grains. A Fortran code has been developed that couples the model to a finite element solver. 
Type Of Material Improvements to research infrastructure 
Year Produced 2020 
Provided To Others? No  
Impact The CP-FE code is providing information on the homogenisation of microscale fields for used by component level models. 
 
Description AWE Materials modelling symposium 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Invited to present and discuss current state of the art on multiscale materials modelling. Presented outputs from the microstructure modelling methods developed in the project. From the meeting discussions followed on the application of crystal plasticity to solve high strain rate problems.
Year(s) Of Engagement Activity 2019
 
Description MAPP: Alloys for Additive Manufacturing Symposium 2018 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact To present current work on modelling microstructure development of additive manufactured parts, including the CA-FD approach for prediction of dendritic and grain level structures. These led to discussions on the linking variation on microstructure to property predictions as well as interactions with AI modelling strategies.
Year(s) Of Engagement Activity 2018
 
Description NNUMAN Community event 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Invited to give an overview of multiscale modelling for the nuclear sector and presented outputs from the project on crystal plasticity. The presentation lead to invitation to talk to experts at the NARMC on materials modelling.
Year(s) Of Engagement Activity 2019
URL https://namrc.co.uk/wp-content/uploads/2020/04/Simple_report.pdf
 
Description Scientific Impact Article 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Article titled "Reflecting light on manufacturing processes and materials" in Impact published by Science Impact Ltd. The article is aimed at disseminating the work being carried out within the EPSRC project on 'An integrated (ICME) approach to multiscale modelling of the fabrication and joining of powder processed parts' to a wide audience in industry and policymakers. The article highlights the potential benefits of Integrated Computational Materials Engineering (ICME)which include increased efficiency, shorter times to market, decreased material input, reduced operation times, increased dimensional accuracy and better performance'
Year(s) Of Engagement Activity 2018