“Following my undergraduate studies in Chemistry and Biology at the University of Malta, I moved to the UK where I spent three years at University College London, doing a PhD in Heritage Science. The research project that I conducted there focused on degradation of colour photographs. Upon finishing my PhD, I was looking for a job, ideally in material degradation, corrosion, or something along those lines. I spotted an advertisement for a vacancy at Danfoss, applied, and got the job, approximately four and a half years ago.”
Helmut’s story is almost identical, except that it begins a few years earlier and in a different country. “I am educated in my native Germany where I first received a Master’s degree (Dipl.-Ing.) and then obtained a PhD (Dr.-Ing.) in Physical Metallurgy, both from the Technical University Bergakademie Freiberg. My doctoral dissertation was on grain growth in metallic materials.
Danfoss Technology Centre
As Materials & Processes Consultants, Ann and Helmut cover related areas of expertise; Ann focuses on corrosion and surface treatments of metals, while Helmut is responsible for addressing all questions related to metallurgy. As he explains, “there is a lot of overlap between our work so if there is a corrosion-related question, Ann can deal with it, I can address it, or we simply start together and then move on as deemed best, depending on the task. And for the final conclusions we may ask one of our colleagues for help. Besides us we have another colleague specialised in corrosion, one in polymers, one in joining (mainly welding and brazing), and two in failure analysis and electronics.”
Adding to this, Ann says: “We work quite closely together on certain tasks, when it is needed. We are all based in the same office so it is easy to approach a colleague and ask a question or discuss results. Our work does not involve much inspection on-site; we are mainly based in the laboratory or go out for meetings at the factory. This is mainly due to the fact that the parts we deal with are normally quite small so they can be sent to us, but occasionally there are situations when we go abroad.”
Among the most common issues experienced by materials specialists dealing with metals is corrosion. Possible causes of corrosion in Danfoss products are typically related to water and various kinds of pollution. Ann elaborates on this: “In my work I consider the issue of corrosion from two different perspectives. The first one is concerned with quality assurance and maintenance. More specifically, before we launch a new product, or when we are developing a new product, we think about the environments to which the product in question might be exposed. To make sure that the right material has been specified, we carry out tests which tell us whether the product, for example a compressor, will withstand the environment in which it is likely to operate.
The other perspective takes into account customer feedback and concerns products already in use. Because it is difficult to foresee every possible situation, problems like corrosion can occur. In such rare cases we first try to identify the root of the problem – did it occur due to poor installation, was the product installed in an environment for which it hadn’t been intended, was the cause some other failure – and then focus on finding a solution.”
When asked about specific types of corrosion they encounter, Helmut replies: “If you take a textbook on corrosion, there are always long lists of different types of corrosion.
I think we have met most of them over the years, if not all. However, typical environments in which Danfoss products are used are not as harsh as those characteristic of, say, the oil & gas or chemical industry. More often than not, Danfoss products are designed either for indoor environments or onshore locations where salinity is not a major threat.
As the discussion moves to stainless steels, Helmut offers an interesting perspective on their relevance for Danfoss products: “There are many end-users who almost solely rely on stainless steels. By contrast, we are the kind of enduser for whom stainless steel is indeed important, but at the same time only one among many other metals and nonmetallic materials. There are Danfoss products that are almost entirely made of stainless steel and others where there is hardly any stainless steel.
Stainless steel is often specified because it doesn’t require surface coating. The same material delivers consistent strength and corrosion resistance. Otherwise you get the strength from the base material and the corrosion resistance from the coating. Yet another advantage of stainless steel is its good weldability. We do a lot of laser welding so this is an important material property.”
“Concerning metals, we use classic materials such as cast iron, plain carbon steel and low-alloyed steels, as well as different non-ferrous metals such as copper, brass and bronze. Most Danfoss products are made of a mix of different metals and other materials; polymers like plastic and rubber are used a lot, also electronics. Stainless steel is just one of many materials used.” and super duplex are commonly used.
As the interview was moving to a close, Ann offered to illustrate her and Helmut’s work at Danfoss by way of a concrete example. Speaking about a task that currently keeps her busy, she explained: “One of the tasks I am working on at the moment concerns a part offered by a supplier. This is a component on a product that is likely to be exposed to a coastal environment or an environment where there is a high level of pollution. My first task was to propose materials capable of withstanding such conditions.
The supplier suggested a nickel coating which was very thin. As soon as I saw the recommendation, I realised that this solution will not meet the requirements. So then we started looking at possible alternatives and came up with two suggestions: a zinc-nickel-alloy coating and stainless steel. We then discussed what kind of stainless steel we would go for – would it be 304, 316, or higher up – and at the moment we are at the testing stage. Based on feedback from the supplier, we are now testing a zinc-nickel-alloy coating and type 316 stainless steel. At the moment the tests are running and as soon as the results have become available we will analyse them.
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