In these test we analyze the belleville washers resistance to corrosion in a dynamic application, which means that is working in fatigue cycles.
Same as trials with tension, pieces are subjected under internal tensions (variable in this case), which accelerate the corrosion process of the pieces. On the other hand when we work in dynamic applications, unlike the previous tests, materials resistance to fatigue is also important as well as their resistance to corrosion to lengthen the disc springs’ useful life.
It is important to emphasize that these tests are exclusively valid in the conditions they have been carried out. For this reason they can be used as a reference. In real applications, there may be different conditions that would change the result. Then, in case you would like to study a real application, we recommend you to contact with our technical department.
To realize the test we prepare belleville washers stacks 6x1 (serial stacks of 6 washers) with different samples in stainless steels and standard steel with anticorrosive coatings. Materials and coatings used ar specified in the tests methodology page..
These stackings are immersed in different corrosive solutions working under fatigue until their breakage.
Equipment used for these tests is composed in 3 parts:
The stack is guided internally and without grease. The corrosive solution is pumped, circulating through the pieces in the compression chamber. The pieces are not completely immersed, to avoid the formation of hydrostatic pressures in the inner part of the stack, which could cause additional forces on belleville washers, affecting the test result. All tests are carried out at room temperature.
Two tests are carried out, the first for fatigue cycles between 20% and 80% of the spring compression. The second test is performed for fatigue cycles between 20% and 60% of its compression. In this way we can compare the effect of corrosion in different situations of demand of the disc springs. In both cases, the useful life of the pieces is taken into account until their breakage.
In these tests, the use of 40% magnesium chloride MgCl2 solution was rejected because it was excessively corrosive. The 3% sodium chloride NaCl solution allows us to evaluate the effects of Chloride solutions.
For this corrosion test, fatigue cycles have been established by working the stacks between 20% and 80% of their travel. The test is carried out at room temperature. The measurement in hours tells us the useful life of the stack before the breakage occurs.
|Variants||Diferent Agresive Solutions|
|Spring + Material + Manufacturing Method||Deionized Water||3% NaCl||0,1 n NaOH||0,1 m ácido|
|C-63 - 1.4310 - Stamping - Rectified||14.171||17.952||37.767||22.280|
|C-63 - 1.4310 - Stamping - Rectified - Shot Peneed||18.255||20.300||38.033||25.389|
|C-63 - 1.4568 - Stamping - Rectified||12.924||17.207||32.747||19.520|
|C-63 - 1.4568 - Stamping - Rectified - Shot Peneed||20.480||24.823||34.555||20.090|
|C-63 - 1.4568 - Stamping - Rectified - Shot Peneed - Kolsterised||11.339||22.199||32.533||30.883|
|Delta Tone + Delta Seal||24.795||10.355||10.127||5.563|
|Paint diluted in water||22.138||13.469||9.902||4.195|
In the following images we can see the result of corrosion with fatigue in the sodium chloride solution 3% NaCl. The pieces correspond to stainless steel 1.4310 stacks with shot peened treatment. These photos were taken at the end of the fatigue test.
In this second test, we reduced the stack path. Fatigue cycles are carried out between 20% and 60% of their path. Springs are less demanded. The rest determinants remain unalterable both in corrosive solutions and in room temperature.
Comparing with the previous test, through this one we can see not only the influence of the washers corrosion in dynamic applications but we can see the influence of the material’s fatigue in the life of the stacking.
In this table we can see the results:
|Variants||Diferent Agressive Solutions|
|Spring + material + Manufacturing method||Agua Desionizada||3% NaCl||0,1 n NaOH||0,1 m ácido|
|C-63 - 1.4310 - Stamping - Rectified||19.552||21.858||30.037|
|C-63 - 1.4310 - Stamping - Rectified - Shot Peneed||33.236||40.005||51.965||47.338|
|C-63 - 1.4568 - Stamping - Rectified||12.357||17.383||34.692|
|C-63 - 1.4568 - Stamping - Rectified - Shot Peneed||21.845||27.974||41.433|
|C-63 - 1.4568 - Stamping - Rectified - Shot Peneed - Kolsterised||32.933||34.000||40.250|
|Delta Tone + Delta Seal||167.443||240.707||22.578|
|Paint diluted in water||94.033||91.741||15.703|
Results: In No. of cycles