PSI - Issue 19

Lloyd Hackel et al. / Procedia Structural Integrity 19 (2019) 346–361 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Figure 15. Test plate of 316L stainless steel with and without highlighting of cracks Observation for cracking was made after 57.5 hours exposure to MgCl2 at 155°C. Cracks extensively developed in un-peened areas, did not develop in peen areas and arrested as they propagated from un-peened into peened areas. Pre-existing scratches in the peened region did not crack.

Figure 16. Magnified view of stress corrosion cracks (highlighted on right) that initiated and grew in the unpeened area. Cracks arrested upon reaching the laser peened region. No cracks formed in the laser peened region.

Figure 17. Additional stress corrosion cracks in the un-peened region with magnified inset. Stress corrosion cracking in the un-peened region initiated about a pre-existing scratch.