Development of Novel Coatings for Hot Stamping Processes

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BackgroundTata is one of the leading global suppliers of automotive steel projects. With light weighting and improvement of crashworthiness being 2 of the key challenges facing the automotive industry at present; hot stamping is well known approach for improving the strength to weight ratio of certain components used in this industry, enabling comparable strengths at lower thickness. This works through linking the martensitic hardening characteristic exhibited by advanced high strength steels with the well understood benefits of deep drawing processes to enhance plastic formability performance while eliminating spring back. In this process, the steel is heated to austenising temperatures, formed and then cooled rapidly to give the desired microstructural properties. Two problems can occur during this process, firstly decarburisation takes place during heating which can negatively affect mechanical properties, secondly oxidation occurs meaning there is a requirement for blast cleaning before forming. If these issues can be overcome without infringing on existing IP in the marketplace there is a considerable amount of new business (~6000t) which could be exploited through UK based Original Equipment Manufacturers (OEMs) localising their supply. AlSi based coatings have shown a great deal of promise at solving these challenges while fulfilling other key OEM requirements, however Arcelor Mittal have filed a suite of patents over the last ~20 years meaning this technology is very strongly protected, therefore an alternative would be required in order to exploit this potential new business. Project Aims/ObjectivesArcelor Mittal has a strong suite of patents protecting their AlSi hot dip coating technology meaning that alternatives need to be sought. In addition, AlSi based coatings only offer barrier corrosion protection as opposed to galvanic corrosion which is typically seen in metallically coated steels. This project will examine novel metallic coatings which can be used to provide galvanic protection and survive the hot stamping operations. Firstly, a literature review of possible technologies will be performed to appraise different solution types relative to a set of Key Performance Indicators (KPIs) determined by the business unit and end users. Once this is completed, technologies which appear promising will be down selected for a laboratory scale feasibility study, one possible method for coating deposition is the hot dip simulator at Swansea University. Coated samples will be characterised and tested to ensure their performance is in line with expectations and all of these findings will be reported.