SCC Crack Growth Rate Testing of LPBF Additive 316L SS

Abstract

The stress corrosion crack (SCC) growth rate of additive manufactured 316L stainless steel was evaluated in three conditions using duplicate specimens: 23% cold worked base metal specimens, weld HAZ aligned specimens, and as-received base metal specimens. In broad terms, the additive manufactured (AM) material behaved similar to wrought material in the same condition, although the higher yield strength of the as-received material (relative to annealed wrought material) may have resulted in slightly higher SCC growth rates in that condition.

Corrosion potential (normal water chemistry with 2 ppm dissolved oxygen vs. hydrogen water chemistry with 63 ppb dissolved hydrogen) had a pronounced effect on SCC growth rate in AM materials, as in wrought stainless steel. The effect of 30 ppb sulfate in normal water chemistry was limited, again parallel to the behavior of (unsensitized) wrought stainless steel.

Most data were obtained in 288°C water, but about a quarter of the testing was done in 320°C PWR primary water with 600 ppm B as H₃BO₃ and 1 ppm Li as LiOH. The SCC growth rates were consistent with the observations in wrought stainless steels and nickel alloys.