The aluminum coating on steel (coating weight 1 oz/ft*, 2 mils 
thick on each side) was about 50 percent gone with bare steel exposed 
in some areas. 
The zinc coating on steel (coating weight 1 oz/ft2, 0.84 mils 
thick on each side) was completely gone and the steel was rusted. The 
corrosion rate of the zinc coated steel in the bottom sediments was 
about the same as the average for the bare steel specimens, indicating 
that the protection afforded by the zinc was of short duration. The 
corrosion rate of the zinc coated steel in seawater was 76 percent of 
the average for the bare steel specimens, indicating that the zinc 
coating had protected the steel for a longer period of time in the sea- 
water than in the bottom sediment. In other words, the zinc had pro- 
tected the steel for about 6 weeks of the total 27 weeks of exposure. 
Comparing the two, the aluminum coating will protect steel for a 
considerably longer period of time at depth in seawater and in the 
bottom sediments than will an equivalent weight of zinc coating. 
Two precipitation hardening stainless steels (362 and 455) in two 
precipitation hardened conditions (H950 and H1050), unwelded and welded, 
were painted with different paint coatings as given in Table 8. The 
bare 362 and 455 in both the H950 and H1050 heat treated conditions, 
unwelded and welded, were attacked by scattered pinpoint pitting and 
incipient crevice corrosion with selective attack in the form of deep 
pits in the weld bead of steel 362 in the H1050 condition. There was 
some flaking of Paint No. 1 (Table 8) and rust stains penetrated 
through the paint coating in some areas on both 362 and 455 alloys. 
There were no failures of paint coatings numbers 2, 6 and 7. 
High strength-low alloy steels numbers 4, 5 and 13 were painted 
with paint coatings numbers 1, 4 and 5. The performance of paint coat—- 
ing number 1 on high strength-low alloy steels numbers 4, 5 and 13 was 
about the same as on alloys 362 and 455 in that rust stains had pene- 
trated the paint coatings in some areas. Paint coating number 5 on 
the high strength-low alloy steels did not fail. Paint coating number 
4 did not fail on high strength-low alloy steels numbers 5 and 13, but 
there was incipient paint failures and rust stains through the coating 
on high strength-low alloy steel number 4. 
Titanium Alloys 
The chemical compositions of the titanium alloys are given in 
Table 9 and their corrosion rates and types of corrosion in Table 10. 
There was no visible corrosion on any of the alloys except the 
13V-11Cr-3A1l alloy partially embedded in the bottom sediments which 
failed by stress corrosion cracking. The stress corrosion cracks were 
normal to the weld beads and extended radially across the weld beads. 
Some of the cracks branched after they crossed the weld beads and 
propagated parallel to the weld beads. 
