Project Description

Key information

Project title: PLEDGE: Particles on the Edge
Project in the Spotlight: N22012
Funding: NWO Open Technology Programme 2023
Research partner: Eindhoven University of Technology (TU/e)
Industrial partners: Tata Steel Nederland, Metalsa, Bosch Transmission Technology
Status: Ongoing – year 2 of 4,5

 

Now in its second year, the PLEDGE project has completed its initial literature studies and established the foundations of its experimental and numerical research programme. The consortium is currently developing novel experimental and modelling tools to investigate the role of second-phase particles in future green steels.

Background

For decades, advanced high-strength sheet steels have enabled lighter, safer and more resource-efficient vehicles. By continuously increasing steel strength, manufacturers have been able to reduce material usage while maintaining structural performance. In the automotive sector, increasing steel strength from 600 MPa to 800 MPa can reduce material usage by approximately 25%, resulting in substantial reductions in both material consumption and associated CO₂ emissions. Today, the steel industry is entering a new phase of innovation, driven by the need to reduce carbon emissions and accelerate the transition towards more circular steel production.

To achieve these goals, steelmakers are increasing the use of recycled steel scrap and developing new production routes based on hydrogen instead of coal. While these developments are essential for achieving climate goals, they also introduce new challenges. Changes in raw materials and production routes can alter the steel microstructure, potentially affecting the properties that make advanced high-strength steels attractive for demanding applications.

This is particularly relevant for sheet steels used in automotive and transportation applications, where manufacturing performance and structural reliability are critical requirements. Before becoming part of a vehicle, these steels are cut, shaped and formed into complex components. Their performance during manufacturing and service depends on a delicate balance between three key properties: edge ductility, cut-edge smoothness and fracture toughness. Together, these determine whether a component can be manufactured reliably, withstand cyclic loading and maintain structural integrity throughout its lifetime. Improving one of these properties often comes at the expense of another, making the development of future high-performance steels increasingly complex.

At the heart of this challenge are second-phase particles: microscopic constituents embedded within the steel microstructure. As steel production becomes increasingly circular, understanding how these particles influence material performance becomes more important than ever.

Project Goal

The objective of the project is to unravel how second-phase particles influence edge ductility, cut-edge smoothness and fracture toughness in advanced high-strength steels, and to use this knowledge to develop microstructural design strategies for advanced high-strength steels produced through future green steelmaking routes.

Second-phase particles are a key building block of modern high-strength steels. They contribute to the high strength levels required for lightweight applications, but also influence local deformation, damage initiation and crack propagation. As a result, they play a decisive role in the balance between edge ductility, cut-edge smoothness and fracture toughness.

The project seeks to understand the micro-deformation processes that govern these competing properties and limit their simultaneous improvement. Particular attention is given to the role of particle size, morphology and distribution, as well as their interaction with grain boundaries and the surrounding microstructure.

Building on this understanding, the project aims to identify how tailored second-phase particle distributions can enable simultaneous improvements in edge ductility, cut-edge smoothness and fracture toughness. At the same time, it investigates the adverse effects of unintended particles and impurities introduced through more circular steel production.

The resulting knowledge will provide a scientific foundation for designing future generations of advanced high-strength steels that combine excellent manufacturability, durability and structural integrity with the requirements of more circular steel production.

Approach

To achieve these objectives, the project combines advanced microscale experiments, state-of-the-art numerical modelling and industrial validation in a fully integrated research approach. By integrating these complementary approaches, the consortium aims to establish direct links between microstructural features and the engineering properties that determine steel performance.

The experimental research focuses on revealing how second-phase particles influence local deformation, damage initiation and crack propagation within advanced high-strength steels. To this end, the researchers are developing an innovative integrated microscale testing methodology, that combines in-situ scanning electron microscopy (SEM) with mechanical testing, digital image correlation and element analysis techniques. This enables strain fields to be measured directly around characterized individual particles and inclusions, providing unprecedented insight into how specific (sub)micron particles influence damage initiation and early-stage fracture.

The experimental observations are complemented by advanced numerical models that simulate realistic steel microstructures and their fracture behaviour. These models are used to investigate how particle size, volume fraction, distribution and phase contrast affect local stress concentrations, damage evolution and fracture. By combining experiments and simulations, the project aims to establish direct links between particle characteristics and the resulting engineering properties.

To ensure industrial relevance, the project works closely with Tata Steel Nederland, Metalsa and Bosch Transmission Technology. The insights and models developed within the project are validated using industrially relevant steel grades and application-oriented case studies, creating a direct pathway from fundamental materials science to future green steel applications.

Impact

By improving the understanding of second-phase particles and their role in future green steels, the project contributes to the development of lighter, safer and more sustainable products. The resulting insights will help steel producers and downstream users develop advanced high-strength steels that remain robust as recycled content increases and steelmaking routes evolve. In the longer term, this knowledge can support material-efficient product design, reduced manufacturing waste, extended component lifetimes and lower CO₂ emissions across the value chain.