All-Russia Institute of Light Alloys, Moscow, Russia:

V. S. Sinyavskiy, Chief Researcher, e-mail: jkmufcjhjrbyf@yandex.ru
I. B. Ber, Chief Researcher
A. V. Vostrikov, Leading Researcher
N. M. Grits, Chief Researcher

All-Russia Institute of Light Alloys developed the method for definition of sulphide corrosion resistance of the alloys, passed through the granuleprocessing stages. According to this, the method is more correct than the passport method, which doesn’t take into account the products manufacturing technology. The passport method results vary from 3 to 9 points (from the corrosion absence to the low-stable state). This is connected with the irregular compound of sulphates and chlorides, because sulphide and chloride corrosions are developed by various mechanisms. Corrosion resistance is increased to 3 points (almost the lack of corrosion), together with increasing holding time from 30 to 500 hours, as well as with exploitation. According to this, testing results according to the method of the Institute of Light Alloys are correlated to the results of the assessment of the state of disks after exploitation. Negative influence of sulphide corrosion on heat resistance is caused by the increasing the number of cracks on the initial stage, which are referred to the corrosion stress cracking. Increasing the number of heatings during exploitation increases the resistance to this type of cracking. According to this, heat resistance after exploitation under the influence of sulphide medium is higher, than initial heat resistance. The measurement procedure MI 26-NKK-14 (МИ 26-НКК-14) was patented on the basis of investigation of the results of measurements and optional control on sulphide corrosion disks, manufactured by the Institute of Light Alloys.

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