Effect of copper on formation and adhesion of low carbon hot-rolled steel strips

Abstract

The understanding of scales adhesively bonded requires several adhesion test method. Adhesion behaviour focuses on adhesive between scales-steel interface associated with scales formation and mechanical adhesion. This information on interface is typically obtained from tensile and pickling tests. Such information can give an indication of the adhesive strength of the interfaces. The hot-rolled low-carbon steel containing copper is focused on scales adhesion studies accomplished in laboratory. The key principle for good result is conception of an experimental method. Typical tensile testing machine equipped with a CCD camera has been adapted to investigate the scale failure. Classical gravimetric weight loss method has been conducted to assess corrosion rate. The scales morphology and cross-section of the samples are observed by scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS). Phase identification is determined by X-ray diffraction (XRD). Much effort is needed to carefully assess scales adhesion. The test exposed the effect of copper composition selected to achieve hot-rolled steel properties on the formation and adhesion of oxide scales. Adhesive strength involves possible contributions from physical, chemical and mechanical. Characterisation of the scales-steel interface after the test would be much useful for exact investigation and still as a significant challenge. The experiment shows that element copper is already obvious at interface of relatively high levels of Cu of 0.225%. This effect is even decreased the adherence of oxide scales on the steel substrate by forming copper-rich phase at interface. Steel industry should more apply techniques such as tensile test for scales adhesion determination. This research is continuously looking for new method to assess scale adhesion. Consideration with results indicates that the element copper should more reasonably estimate for its effect to industrial descaling process.