Abstract
Diagnoses and remedies of corrosion failure of 13 Cr martensitic stainless steel parts used for hydraulic machines in fresh water at ambient temperature and in high purity water at high temperature are presented. The failures of the rotation parts in the hydraulic machines were occurred by SCC or corrosion fatigue induced with pitting and intergranular corrosion in these mild environments. These localized corrosion may be attributed to the sensitization by medium tempering temperature of 13 Cr martensitic stainless steels. On the other hand, the failures of the sliding contact parts in the hydraulic machines were occurred by brittle fracture induced with micro-pitting. These failures may be attributed to the presences of the abnormal stress caused by high hardness of hydraulic machine in service duration. Possible methods to prevent these failure may be use of the non-sensitized materials by full annealing for rotation parts and be use in the normal stress condition for sliding contact parts. No failure has been reported for over long duration since the countermeasures had been adapted.
