pressure. When a terminal was removed from one end 

 of each specimen, the zinc coatings were gone from 

 the portions of the ropes which had been inside the 

 terminals and the wires of the strands were rusted. 

 The polyethylene jacket on one rope (number 9) had 

 been punctured in many places prior to exposure. 

 After exposure these holes were filled with white cor- 

 rosion products; there was pressure underneath the 

 jacket; and there was no rust on the wires except 

 inside the terminals. 



Rope numbers 39, 43, 44, and 45 were alumi- 

 nized (coated with a layer of aluminum). Aluminum 

 coatings afforded considerable protection to steel 

 ropes in the same manner as did zinc coatings. A 

 0.38-oz/sq ft of aluminum coating (1.4 mils thick) 

 afforded protection to steel rope for about the same 

 period of time as did an 0.83-oz/sq ft of zinc coating 

 (1.4 mils thick). In deep-ocean environments, equal 

 thicknesses of coatings of zinc and aluminum pro- 

 tected steel ropes for about the same periods of time, 

 but on a weight basis zinc was about twice as heavy as 

 aluminum. There was no decrease in breaking 

 strength caused by corrosion. Also, rope number 39 

 was not susceptible to stress corrosion when stressed 

 at 20% of its breaking strength. 



Rope numbers 10, 11, 12, 13, 14, 15, 16, 17, 29, 

 30, 31, 32, 33, 34, 41, and 42 were stainless steels of 

 different chemical compositions. The 0.1875-inch- 

 diameter Type 304 stainless steel ropes (10, 11, 12, 

 13, 29, 30, and 31), stress relieved and not stress 

 relieved, were corroded by crevice, pitting, and 

 tunnel corrosion; and many of the wires had parted 

 because of corrosion, particularly internal wires. 

 There were only rust spots on the larger diameter, 

 O.250-through-0.375-inch, Type 304 ropes (32, 33, 

 and 34) for equivalent periods of exposure. The addi- 

 tion of vanadium and nitrogen (rope number 16) to 

 the Type 304 composition did not improve the cor- 

 rosion resistance of the Type 304 stainless steel. The 

 addition of copper (rope number 14) to the Type 3 16 

 stainless steel composition impaired its corrosion 

 resistance, while the addition of silicon and nitrogen 

 (rope number 15) did not appear to have any influ- 

 ence. The conventional Type 316 stainless steel (rope 

 number 41) was uncorroded after 751 days of 

 exposure, but after 1,064 days there were many 

 internal wires broken as a result of attack by crevice 

 corrosion. The breaking strengths of most of the 



stainless steel ropes were impaired by exposure in sea- 

 water at depth. Rope numbers 41 and 42 were not 

 susceptible to stress corrosion when stressed at 20% 

 of their respective breaking strengths. 



Two Type 304 stainless steel ropes (numbers 46 

 and 47) were clad with 90% copper-10% nickel alloy. 

 Rope number 46, which had a clad layer 0.7 inch 

 thick, had a green color after 402 days of exposure, 

 indicating that the Cu-Ni clad layer had not been 

 completely sacrificed. However, rope number 47, 

 which had a clad layer 0.3 mil thick, was covered 

 with a light film of rust, indicating that it had been 

 completely sacrificed during the same period of time. 

 In both cases the internal wires of the ropes were 

 uncorroded. 



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