In the appliance industry, galvanized sheets must reliably undergo transport, forming, and painting. Our chrome-free passivation supports stable surfaces, good paint adhesion, and a lasting high-quality appearance.
Passivation – the additional protective layer for your galvanized surfaces
After galvanizing, the steel surface is usually coated with a very thin, transparent passivation layer. This layer stabilizes the zinc surface, protects against so-called white rust during storage and transport, and supports downstream processes such as forming and painting.
For you as a user, this means better surface stability, greater process reliability, and more flexibility in logistics and temporary storage—especially in demanding supply chains.
Chromium(III), chromium(VI), chromium-free – what's behind it all?
Chromium-based systems have a long tradition in industrial passivation. Today, passivation based on chromium(III) is predominantly used. Chromium(III) is considered an essential trace element and is regarded as safe in common applications.
Chromium(VI) is much more critical: it is highly toxic and classified as carcinogenic, which is why chromium(VI) compounds are subject to strict regulations in Europe. They have already been largely replaced in many applications.
Chromium-free passivation goes one step further: it completely dispenses with chromium and uses alternative chemical systems. The aim is to meet technical requirements on a permanent basis – while minimizing regulatory risks for your material approvals and delivery approvals.
REACH & Co.: Changes affecting chromium – and what is relevant for you
Chromium is not being banned outright in Europe. The key distinction is between chromium(III) and chromium(VI). Strict approval and restriction rules have already been in place for various chromium(VI) compounds for many years. It is foreseeable that regulatory pressure will continue to increase in this area.
Chromium(III)-based passivation processes are still permitted and are now the standard in many steel applications. At the same time, stricter requirements for chromium(VI) precursors may make the production of such systems more complex and costly – or cause it to shift to regions with less stringent requirements.
For you as a customer, this means that it makes sense to be aware of options that do not use chromium at all in the medium and long term. This gives you leeway to further develop your own material guidelines and sustainability goals.
Our chrome-free passivation – tested, approved, ready for your applications
As part of a development project, thyssenkrupp Steel has comprehensively tested a chrome-free passivation for galvanized flat steel. Corrosion protection, surface stability, and suitability for downstream processes were examined in laboratory and practical tests. The system has been approved and can be used for defined applications.
We currently use chrome-free passivation specifically where you have to meet specific requirements for chrome-free surfaces. Due to the chemicals used, passivation is currently more cost-intensive than our established chromium(III) passivation processes. We therefore provide you with individual advice on whether and where it makes sense to use it for your components and supply chains.
In the field of packaging steel, thyssenkrupp Steel has many years of experience with chrome-free passivation. We use this expertise to reliably design solutions for other applications as well.
Comparison of chromium(III) passivation and chromium-free passivation
Depending on the application, either chromium(III) passivation or chromium-free passivation may be the right choice. The following overview will help you make an initial assessment:
