Projects dealing with fracture toughness

Tough-Sheet
07/2014 - 06/2017

The first RFCS project addressing the evaluation of fracture of thin AHSS sheets to better understand crash resistance and formability during service or forming. It demonstrated that fracture toughness, measured following the essential work of fracture (EWF) methodology, can be effectively used to classify and understand edge cracking and the impact performance, as well as other fractures related to the local ductility of AHSS and PHS. Such assertion was supported by extensive stretch-flangeability and impact tests (bending and axial) in different AHSS grades, including the most representative families of 1st, 2nd and 3rd Gen AHSS as well as press hardened boron steels.

Fracture toughness introduced in the development of new steel grades
iCut
07/2015 - 12/2018

Integrative cutting solutions to produce high performance automotive components with high-Mn steel sheet. Three different TWIP steels grades were characterised. iCut showed large twinned areas around the cut edges, which show low fracture toughness. This local effect must be considered when using fracture toughness to understand edge cracking. It is solved by measuring fracture toughness in deformed specimens. The fracture toughness drops from 303 KJ/m2 in virgin material to 187 KJ/m2 in deformed TWIP.

OptiQPAP
07/2016-12/2019

Optimisation of performance properties of the Q&P steels for their application in automotive industry. Fracture toughness was measured in the development of quench and partitioning steels.

NANOFORM
07/2016 - 12/2019

Improved formability in 3rd generation AHSS steels by nanosize precipitation and microstructure control during and after hot rolling. Fracture toughness was considered in the development of a Complex Phase (CP) steel with UTS of 1000 MPa and high formability. New steels show very high fracture toughness, 379 and 778 KJ/m2.

Crash&Though
Started 07/2018 - ongoing

Towards high crashworthiness parts through the investigation of microstructural effects on fracture toughness of 3rd generation AHSS. The project uses the good correlation between toughness and crashworthiness to develop new TRIP-aided AHSS grades. The values of essential work of fracture are used to discern the role of retained austenite in the fracture resistance and crashworthiness.

WarmLight
Started 09/2018 – ongoing

Development of a methodology for lightweight design of warm formed components with complex geometries in heavy vehicle applications. Fracture toughness is used as a material property to estimate the fracture resistance in the development of new steel grades for warm forming of high strength steels. Warm forming allows to manufacture crash resistant parts for heavy duty vehicles, so the measure of fracture toughness it crucial to reach the project goal.

CuttingEdge4.0
Started 06/2019 - ongoing

The project deals with Industry 4.0 solutions for manufacturing complex parts with AHSS, which show high risk of edge cracking. Production failure algorithms will be developed following Artificial Intelligence methodologies. Fracture toughness of processed steels (Dual Phase and Complex Phase) is measured to select the best material to avoid edge cracking. It is also measured in different production steel batches using a fast-testing method to detect the property variation during long-term production and to rationalize cracking problems if they occur during production.

Fracture toughness as a property for material selection and characterisation
FormPlanet
Started 01/2019 – ongoing

FormPlanet, incorporates the measurement of fracture toughness as a property for material selection and characterization. FormPlanet addresses fracture toughness measurements for different sheet materials (thin and thick) and for different industrial applications.

A fast-testing method for fracture toughness measurements following the essential work of fracture methodology has been developed and patented. This new method is expected to boost the applicability of fracture toughness by steel makers, part producers and OEMs as a routine test for steel quality qualification. The application of the essential work of fracture methodology to the evaluation of toughness in thick plates (hot rolled steels) is assessed.