Inclusion analysis in a dual-phase automotive strip steel

Abstract

A holistic assessment of inclusions present within a cold rolled DP800 steel was performed. The assessment comprised a variety of methods including optical microscopy and image processing, alongside quantitative, statistical analysis. The ‘statistics of extreme values’ approach was applied, utilising outputs from microstructural analysis. A qualitative analysis followed via the use of SEM and EDS to determine the morphologies and compositions of inclusions within the material. This has allowed for cross-coil examination; identifying the variation in behaviour of inclusions through the width of a cold rolled strip, which can be correlated with slab solidification as well as final product performance. This understanding is also critical in informing sample extraction for microstructural characterisation and mechanical property assessments. The research has provided an accelerated methodology of inclusion analysis that can be applied to DP800 effectively, allowing for manufacture-microstructure relationships to be determined.