Preventing Stress Corrosion Cracking and Enhancing Corrosion- Fatigue Performance of Steel and Aluminum by Laser Peening; deployment on nuclear spent fuel canisters.
Author: A Lloyd Hackel1, B. Jon Rankin1, C Matt Walter1, D Brent Dane1 1 Curtiss-Wright Surface Technologies, 222 Mountain Vista Parkway, Livermore, California, 94551, USA
Source: ICSP14 Milan
Doc ID: 2022051
Year of Publication: 2022
Abstract:
We report test results showing that laser peening prevents chlorine induced stress corrosion
cracking (CISCC) of welded 316L stainless steel and 5000 series aluminums. Our previous
work shows similar success preventing cracking in Hastelloy 22, Inconel 600 and Inconel
690. Based on published work identifying the importance of deep (>1 mm) compressive
stress to prevent pitting from transitioning into cracking, we provide measurements of the
multi-mm depth of compressive stress generated by laser peening in these steel and
aluminum materials. The stainless steels tests are important for multi-purpose canisters
(MPCs) used for spent nuclear fuel storage and the aluminum panels have important
applications in Navy ship and marine applications that have be plagued by sensitization
cracking of 5000 series aluminums. Using ASTM G36 (2013) accelerated corrosive testing
we decisively show that CISCC does not initiate in weld areas of 316L stainless steel that
were laser peened. We further show that for 5083 and 5456 aluminums, laser peening
inhibits sensitization and most importantly prevents crack initiation or growth in thermally
exposed panels with treatment either before or after sensitization level exposures. The
testing of both the stainless and aluminums clearly shows that cracking will initiate and grow
in non-peened regions, will not initiate in laser peened areas and that all cracking arrests
upon propagating from non-peened areas into laser peened areas. In our work, test panels
were exposed to a solution of magnesium chloride at 155oC and rapidly showed extensive
cracking in non-peened areas. Based on the results of this work, the laser peening
technology was approved by the NRC and used to protect the spent nuclear fuel canisters
for the San Onofre Nuclear Power Plant.
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