Controlled Surface Rolling: A Novel Low Plasticity Burnishing Technique to Mitigate Stress Corrosion Cracking in Machined SS304L

Abstract In this work, controlled surface rolling (CSR), a novel roller based low plasticity burnishing technique, was developed to mitigate initiation of stress corrosion cracking (SCC) in machined SS304L in chloride environment. This setup utilized a pneumatic system to apply controlled loads (upto 1000 kgf), with CSR performed by varying roller velocity and number of rolling passes. Advanced characterization techniques, like electron back scattered diffraction (EBSD), nanoindentation, and 3D optical profilometer were used to characterize changes in microstructure and surface roughness resulting from CSR. These results were compared with conventional shot peening. The depth up to which misorientation within the grains observed in EBSD, which is an indicator of plastic strain induced on the surface, didn’t increase significantly due to CSR treatment (77 µm) on as-machined sample (62 µm). Residual stresses along both circumferential (σ C ) and radial (σ R ) directions with respect to machining tracks were measured using synchrotron X-ray beam, and correlated to SCC density from ASTM G36 test. The SCC density in as-machined condition reduced by 99% after CSR treatment at 800 kgf, 10 mm/s and 20 passes. A significant reduction in SCC density was also achieved after CSR at 200 kgf due to small reduction in tensile σ C in as-machined condition. While after CSR treatment at 1000 kgf, compressive stresses were observed along both the directions (σ R : − 512 MPa, σ C : − 72 MPa).