This Is The Application of Cold Spray Technology for the Protection of 304 Stainless Steel Against Stress Corrosion Cracking

Austenitic Stainless Steel 304/308 are the materials of choice in the design of nuclear waste storage facilities. Austenitic Stainless Steels are susceptible to Stress Corrosion Cracking (SCC) when exposed to Chloride environments for long periods at temperatures exceeding 60^ᵒC. This long-term material degradation mechanism is a pertinent risk factor which could cause a containment breach if mitigation and prevention measures are not explored and implemented. This work is concerned with the introduction of compressive stresses via Supersonic Powder Deposition & Consolidation (Cold Spray) Technology reducing susceptibility to SCC as a counter-balance against tensile stresses promoting SCC.

Cold spray is a low temperature coating process in which particles are injected into a high-pressure gas flow that is accelerated through a converging diverging nozzle to supersonic velocities. When the particles impact a typically metallic substrate they inelastically deform creating ballistic impingement and metallurgical bonding with the substrate. This avoids unwanted thermal effects, introduces compressive residual stresses, replaces lost material, and can be done in situ, thereby greatly reducing the cost of repair by avoiding teardown/ removal costs. Characterization techniques will include Cyclic Polarization Testing in accordance with ASTM G61, immersion testing in accordance with ASTM G36, XRD analysis and Photon Microscopy.