MATERIALS AND COATINGS
To prevent corrosion in belleville washers there are two options: we can use stainless steel or we can apply a coat over the standard steel part.
Choosing one option as well as a specific coating or material will depend on the environment conditions of the piece as well as its required duration and also the cost that we can afford. To do this selection, we also have to think about galvanic corrosion.
In the following links the information about stainless steel and anticorrosion coating is detailed. Down in this page, we can find a comparative based in three tests which can help us like an orientation.
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It’s important to remark once again that every case is different and this is why we recommend to study every case by itself to be sure we choose the best solution. In this website, we show you some tests results, which ones can help us to choose the best option. However, we should understand that they are based on concrete conditions, and in determinate materials and coatings. In a real case, it can have other conditionings, this is why it is important to study every case per separately.
To compare materials and coatings, we include the results of three different tests. One test of four cycles of the VDA test, frequently used in automotive industry. Another two where we immerse the pieces in two corrosive solutions (a sodium chloride NaCl solution at 3% and in a magnesium chloride MgCl2 solution at 40%) during four weeks at room temperature.
In this way, we can observe the behavior of the pieces before different corrosive agents. It is important to remark that in any of these three cases, it hasn’t been applied any load to the pieces so it is a test without internal tensils. As we will see in other tests, the pieces behavior will vary if the piece is under external load, static or dynamic.
On the tests methodology page we can find a detailed description of the selected materials and coating for the tests.
| Variants | Tests | ||
|---|---|---|---|
| Type (serie A,B or C) + Material + Manufacturing Method | VDA | 3% NaCl | 40% MgCl2 |
| 1.4310 - C - Stamping - Grinding | G | 0 | +1 |
| 1.4310 - C - Estampado - Rectificado - shot peened | G | 0 | +1 |
| 1.4310 - B - Stamping - Grinding | G | 0 | +1 |
| 1.4568 - C - Stamping - Grinding | M | -1 | 0 |
| 1.4568 - C - Stamping - Grinding - shot peened | P | -1 | 0 |
| 1.4568 - C - Stamping - Grinding - Kolsterised | VP | -1 | 0 |
| 51 CrV4 | |||
| Mechanical zinc plating + Yellow Galvanized | VP | -1 | -3 |
| Mechanical zinc plating + Transparent Galvanized | P | -1 | -2 |
| Dacromet | G | 0 | 0 |
| Geomet | G | 0 | 0 |
| Delta Tone + Delta Seal | M | 0 | -1 |
| Nickel Plating | P | 0 | 0 |
| Paint diluted in water | P | -2 | -2 |
| Oiled | VP | 0 | 0 |
- G - Good (No visible corrosion)
- M - Moderate (Low visible effects of corrosion)
- P - Poor (Surface covered by a thin corrosive layer)
- VP -Very Poor (Surface covered by a considerably huge corrosive layer)
- +2: 2 levels better
- -2: 2 levels worst
- Kolsterised: Treatment to improve resistance against austenitic stainless steels wear.
List of pages in Materials and coatings: