University of Manchester

Scan of Legacy Samples after 18 and 24 Months of Environmental Exposure (Atmospheric-Induced Stress Corrosion Cracking of Duplex Stainless Steel Wires)

Cem Örnek
Project Completed

Scientific Case

The aim of this investigation is to measure corrosion rates and associated stress corrosion cracking propensity of duplex stainless steel (DSS) when exposed to chloride containing atmospheric environment at 50°C. This environmental scenario is directly relevant for the storage of intermediate-level nuclear waste (ILW) in so-called waste drums/containers made from duplex stainless steel. Two different types of duplex stainless steel wires made from grade 22%Cr-2%Ni and 25%Cr-5%Ni DSS with diameters of 500-600 µm have been contaminated with magnesium chloride electrolyte and exposed to a controlled atmospheric environment at 50°C and 30% relative humidity. The wires have been strained using a self-designed corrosion cell and were exposed up to 10 months in a humidity chamber. Previous scans in the MXIF facilitated the characterisation of incubation times or atmospheric corrosion and corrosion morphologies. Nucleation times for corrosion and stress corrosion cracking have been obtained and their short-term propagation characterised. The wires have now been exposed for more than 15 months, and it has key importance to scan the previously scanned wires to obtain long-term data about corrosion and stress corrosion cracking susceptibility.
Other
Nuclear Decommissioning

Experiment Design

XRT machine to be used:
XRADIA Versa

Material type:
Grade 2202 duplex stainless steel wire (Ø = 500 µm)
Grade 2205 duplex stainless steel wire (Ø = 630 µm)

Features of interest:
Pits (corrosion cavities), selective corrosion, and stress corrosion cracks

Estimation of smallest feature size and resolution:
Sub-micron to 10’s of microns (extent of pit/crack length)
Scanners and Rigs
Xradia VersaXCT
20
Not Required
10
n/a

Sample & Safety

The samples to be scanned are:
- Grade 2202 duplex stainless steel wire (Ø = 500 µm)
- Grade 2205 duplex stainless steel wire (Ø = 630 µm)
which were strained using a self-designed corrosion cell made from Persepx tube (see Figure 1 in the PdF-file attached). The wires were contaminated with magnesium chloride electrolyte and the exposed between 18-24 months at 50°C and 30% relative humidity. The cell will be placed into the machine and scanned. There are no sharp edges on the tube, therfore there is no physical hazard expected. No rig is required. A sample holder on the machine is sufficient.
3
Low Hazard

Scan Records

Project Report