Sheet metal forming is one of the most important manufacturing processes to obtain metal parts for almost every industrial production sector: transport, machinery, home appliances, food, cosmetics, energy, chemical, etc. The automotive and aerospace industries are driving the growth of the sheet metal forming industry in the EU, pushed by the constant demands on materials for lightweighting.
Steels and aluminium alloyswill be the dominant engineering materials for such applications in the coming years. The recent developments in the Advanced High Strength Steel (AHSS) grades have definitely contributed to lightweighting and to improve passenger’s safety. By virtue of their strength, AHSS allow downgauging and therefore are the preferred choice over other light metals for weight saving. Nowadays, their application in serial vehicles is higher than 50% in weight.
Recent developments in high strength metal sheets, allowing downgauging and reducing production costs, are essential to drive European industries competitiveness
The future of the EU industries dramatically depends on enforcing high-added value products and cut production costs to face the increasing competition from low-cost countries and the recent USA industry protective strategies by imposing high metal tariffs on EU imports. There is a continuous demand from end-users for high quality and high-performance parts manufactured withhigh strength sheet materials.
New materials – new challenges: manufacturing sheet parts with processing sensitive materials
The vast and rapid industrial implementation of high strength alloys has introduced new problems that are not completely solved: their limited ductility may give rise to unexpected defects during forming, and part properties and quality depend on forming parameters. In this sense, high strength sheet materials can be considered as processing sensitive materials.
High strength sheet materials have been adopted rapidly into the industry but new challenges have arisen related to the difficulties in preventing forming defects
The sheet metal forming sector is facing new challenges related to the manufacture of high-performance parts with new high strength sheet materials, including the prediction of forming defects such as cracks, stretching or thinning.
Different approaches have been used to overcome such difficulties, but despite the progress achieved in this field, the use of new high strength sheetmaterials still represents achallenge to the manufacturing sector, which faces serious problems to reach defect-free production and productivity losses due to the unpredictable occurrence of defects and lack of overall formability during forming.
Traditional approaches (tensile tests, Forming Limit Curves, etc.) do not allow understanding crack-related problems and cannot be used to study the formability of processing sensitive materials.
There is a need for innovative approaches to assess the formability of processing sensitive materials to predict defects at the product design stage and avoid productivity losses
Crack-related and reduced formability are still unsolved issues in the sector and cannot be predicted at the product design stage using traditional experimental or computational approaches. They remain unresolved issues in the sector and hamper the use of new materials and the development of high-performance parts at affordable costs.
FormPlanet, a boost to the sheet metal forming industry
The use of promising high strength sheet materials is currently limited by their processing sensitiveness: forming parameters and material quality must be carefully controlled to assure defect-free production and guarantee part quality. Current and future technology trends, as electrical vehicles or factories of the future (Industry 4.0), require affordable material solutions.
FormPlanet project’s main goal is to tackle the upcoming challenges in formability and part quality assessment by developing knowledge-based testing methodologies to address formability and quality part problems in the sheet metal manufacturing sector, covering a wide range of materials (steel, Al, Ti and Ni alloys, and multi-layer sheet metals).
FormPlanet project will develop novel testing methodologies to address formability and crack-related problems in high strength materials
The developed knowledge and testing methods will permit a detailed evaluation of sheet properties, predict part performance and prevent production losses to the sheet forming industries. This approach will boost a wide usage of high strength materials for high-added value sheet products, while reducing production costs and time-to-market in different industrial end-use sectors.
Novel testing techniques to be developed in FormPlanet
Fracture toughness of metal sheets – Fracture toughness measured in the frame of fracture mechanics allows to predict edge cracking resistance and crashworthiness. However, the industrial sector does not use this property to select materials because of the experimental complexity of the standardised methods. A test to accurately measure fracture toughness in very short time will be developed, making fracture toughness evaluation affordable for industrial characterisation purposes.
Crashworthiness – The development of small-scale laboratory methodologies to predict crash behaviour is essential to optimise material selection and assist new materials development. A new methodology to extract material parameters that influence crash resistance will be developed. The implementation of results in FE modelling will be also assessed.
Room and high temperature formability – FormPlanet will develop a testing machine for the reliable determination of sheet formability at elevated temperatures. It is highly interesting for hot stamping (B steels, Al or Ti alloys), superplastic forming, hot-metal-gas-forming, etc. To measure formability at room temperature, two tests will be used: biaxial tensile tests (cruciform specimens) and deep drawing tests. These tests combine the advantage of reproducing almost any linear and non-linear strain path at different deformation states. The combination of these methods will contribute to understand sheet forming and increase prediction reliability in cold forming.
Part quality assessment and in-process measurements – In process failure-detection techniques and 100%-in process methods of quality control are highly demanded to assess part quality and guarantee defect-free parts. Novel in-process control systems based on High-Frequency-Impulse-Measurement), 3MA systems (Micromagnetic Multiparameter Microstructure and stress Analysis), laser tracking and advanced thermography will be developed and incorporated to sheet forming processes for non-destructive inspection. Additionally, an industrial on-line diffusible hydrogen measurement test will be optimised and implemented to detect H-delayed fractures during steel production, forming and part assembling.
Rapid fatigue testing – Fatigue tests are usually time consuming and cannot be used for routine material characterisation. A new approach based on fracture mechanics will be used to estimate the fatigue resistance by a single and fast test. It will drastically shorten test duration and will allow to consider fatigue properties as a basic mechanical property for material characterisation.
Small specimen characterisation – Small sized specimen techniques are increasingly used for mechanical properties determination when limited amount of material is available. FormPlanetwill improve and optimise micro-tensile tests for mechanical properties determination for lab-scale development of new sheet alloys or to measure local properties of sheet parts.
Dr. Daniel Casellas
PhD in Materials Science. He is the Scientific Director of Eurecat and Adjunct Professor at Luleå University of Technology (Sweden). His research interests are fatigue and fracture of structural materials and micromechanical evaluation, with special focus on the fracture mechanics approach to address crack-related phenomena in high strength metal sheets.