The excellent corrosion resistance of austenitic stainless steel has led to a wide commercial use of these materials.
Best known and applied varieties are Aisi 316(L) and Aisi 304. But also other austenitic stainless steel varieties are, due to their very good corrosion resistance properties, widely used in the automotive, oil & gas, chemical, medical and food industries. A major disadvantage of austenitic stainless steel is the relatively low hardness, low abrasion resistance and sensitivity to seizing (cold welding). This restricts the use in high-quality mechanical applications in various machines, where also these properties are important.
Why not is chosen for a martensitic stainless steel finds its reason in the fact that these materials have a significantly higher hardness and abrasion resistance, but on the other hand have a much lower corrosion resistance.
In the past there have been many attempts to develop a hardening and/or surface technology without affecting the corrosion resistance, but also to improve, for example, abrasion resistance and fatigue strength. Conventional processes such as nitration, boration and coating cannot be used.
Since a number of years there is a process, called Stainihard® NC, which provides a strong improvement from the point of view of abrasion resistance, fatigue strength but also the well-known cold welding (fretting). This, while the corrosion resistance remains unchanged and in some cases is even improved.
It also offers advantages in places where machines should be regularly cleaned. Here Stainihard® NC ensures that foodstuffs, such as milk products, adhere less and thus can easier and faster be removed.
In general it offers the industry a great solution if abrasion-resistance and avoid col welding have to go together with a good to very good corrosion resistance.
An example, where Stainihard is applied, is in the food processing industry where it is worked with stainless steel. In the processing of food, with many movements are being created that cause wear, this influences the operating life of the machine. Often also food residue is deposited. Stainihard limits the wear of the machine parts, who are also easier and faster to clean.
Some examples of products that qualify for this treatment are:
Shafts, rotating parts, drive parts, valve and pump parts, valves, plungers, guides, sleeves, bearings and pistons.
Stainihard® is becoming increasingly well-known in the automotive industry and is therefore increasingly being used. We now find many Stainihard® hardened parts in pump and drive components as well in electromagnetic valves.