Corrosion issues of zirconium materials
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Our facility has several zirconium reactors that have been in use for about 3 years. Recently, corrosion was detected on the shaft sleeves of the mixing blades; however, only the shaft sleeves are corroded, while the blades to which they are welded remain intact. The material composition of all these components has been confirmed to be ZR3. Operating conditions: the medium consists of around 50% nitric acid along with other materials, the temperature is 160°C, and the pressure is 0.9 Mpa. I asked the manufacturer; the shaft sleeve is a forged piece, and I wondered whether the high temperatures encountered during forging could have affected the corrosion resistance of zirconium
Here, the issue concerns the stirrer shaft sleeve; the material of the sleeve is to be upgraded, and zirconium material is to be tried.
Two factors need to be considered: 1. Whether oxidation or other impurities affect the material’s corrosion resistance during the forging of the shaft sleeve； 2. Is there stress corrosion?
This post was last edited by qugd on 2021-11-24 09:22. I think it is caused by the failure to carry out stress relief during the forging process. The blades are made of zirconium material; due to their thin thickness, the stresses generated during processing can be easily eliminated through heat treatment. However, the bearing sleeves are made of thick zirconium material and have undergone forging processes, so the internal stresses cannot be removed easily without thorough post-treatment. During use, the release of these stresses can lead to structural defects in the material, thereby causing corrosion.
Replace it with new wire or weld a new layer using Zirconium 702 wire
As the user of this equipment, you’ve even delved into the heat treatment processes of materials; I suspect you have a degree in a material-related field. According to my teacher at Baotai, different temperatures, as well as the length of heat treatment time at the same temperature, can all affect the properties of the material. It is likely due to excessive or prolonged temperature control during the forging process in a small factory in Baoji.