In recent tests at the Savannah River Laboratory, surface treatments with lithium silicate prevented stress corrosion of sensitized, intergranular corroded Type 304 stainless steel in high purity water that was adjusted to pH 4.5 with HNO3 and contained about 20 ppm chloride. Samples not treated with lithium silicate cracked within 48 hours in the solution, but only one of 33 treated samples cracked within 890 hours, the maximum test time. In untreated samples, crack depth and number increased with exposure time, and an incubation period of 27 hours was indicated. Bergen1 has shown a 400% increase in time-to-failure for stainless steel boiled in 35% sodium metasilicate solution before testing in boiling calcium chloride.
U-bend samples of stainless steel that had previously been shown by Rideout2 to be susceptible to stress corrosion cracking in dilute chloride solutions were used. These samples had been bent, sensitized at 1200 F...
