D2.4 Crash tests for model validation and X-ray microtomography for mapping of defects in HPDC part – Abstract

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The deliverable D2.4 “Crash tests for model validation and X-ray microtomography for mapping of defects in HPDC parts” collects the work done by the Flexcrash consortium in Task 2.3. and it is related to Key Exploitable Results (KER) 3, as listed below.
KER 3: Advanced materials models for crash modelling

One of the two tasks involved in the deliverable was to map the defects formed in the High pressure die casting (HPDC) parts with the help of X-ray microtomography (XMT), focusing on the porosities distribution which are typically formed during the HPDC process and were originally intended to be considered in the failure modelling of the HPDC alloy due to their supposed effect on fracture of the material. Having said that, since many other defects apart from the porosities are also introduced in the material during the HPDC, which cannot be detected using XMT and may also influence the failure of the alloy, first, optical microscope (OM) investigation of HPDC step parts having a wall thickness of 2-, 6- and 10- mm were carried out. Then, as per the demand of the deliverable, XMT analysis was performed on HPDC castings with the abovementioned thicknesses. The XMT analysed castings were then undergone uniaxial tensile tests to perceive the correlation between their tensile behaviour with their porosity content, subsequently intending to use the relationship later in the failure modelling of the HPDC parts. However, the focus was redirected due to the discrepancy in the anticipated outcomes based on the XMT analysis and the actual tensile behaviour, which necessitated additional investigation into the fracture surface. The resultant fracture analysis could only be corroborated and explained accurately with the help of the OM analysis conducted. The results obtained from the current work therefore shift the focus away from porosities as the main contributing factor behind the failure of the HPDC parts onto the more dominant effects presented by the surface skin and cold flake, which need to be considered in the failure modelling of the cast parts for capturing the large spread in their ductility.

The second task involved in the deliverable was to carry out crash box tests for full-field deformation measurements using a high-speed tensile testing machine. However, the tests could not be included in the current version of the deliverable as the test boxes have not yet been received for performing the required experiments. These tests will be reported in deliverable D3.2.