of rust. A clad layer 0.7-mil thick had not been depleted on the 

 outer wires within 1 year of exposure since they were covered with 

 green corrosion products. The internal wires of both ropes were brown 

 in color indicating no sacrifice of the cladding. 



STRESS CORROSION 

 Applied Stresses 



Some of the stainless steels were stressed at 35, 50 and 75 per- 

 cent of their respective yield strengths and exposed in seawater at 

 the surface and at depths of 2,500 and 6,000 feet for various periods 

 of time to determine their susceptibilities to stress corrosion crack- 

 ing. This data is shown in Table 9. 



The 300 and 400 Series stainless steels were not susceptible to 

 stress corrosion cracking in seawater either at the surface or at depths 

 of 2,500 and 6,000 feet. 



Some of the 600 Series precipitation hardening stainless steels 

 were susceptible to stress corrosion cracking in seawater either at 

 the surface or at depth, or both. A1SI Types 630-H925, 632-RH1100, 

 634-CRT and 635 were not susceptible to stress corrosion cracking but 

 Types 630-H925 and 632-RH1100 failed by crevice corrosion at the sup- 

 porting anvils of the stress jigs. 



AISI Type 631-TH1050 failed by stress corrosion cracking at the 

 surface at stresses equivalent to 50 and 75 percent of its yield 

 strength; at the 2,500-foot depth at 75 percent of its yield strength; 

 and at the 6,000-foot depth at 50 and 75 percent of its yield strength. 

 AISI Type 631-RH1050 failed by stress corrosion cracking at the 2,500- 

 foot depth at a stress equivalent to 75 percent of its yield strength. 



Precipitation hardening stainless steel PH14-8Mo-SRH950 failed by 

 stress corrosion cracking at the 2,500-foot depth at stresses equiva- 

 lent to 50 and 75 percent of its yield strength and at the 6,000-foot 

 depth at 75 percent of its yield strength. 



Precipitation hardening stainless steel 15-7 AMV-A failed by 

 stress corrosion cracking at the 6,000-foot depth at a stress equiva- 

 lent to 75 percent of its yield strength. The same alloy in the RH1150 

 condition failed by stress corrosion cracking at the 2,500-foot depth 

 at stresses equivalent to 50 and 75 percent of its yield strength. Also, 

 in the RH950 condition the same alloy failed by stress corrosion crack- 

 ing at the 2, 500- foot depth at stresses equivalent to 50 and 75 percent 

 of its yield strength and at the 6,000-foot depth at 35, 50 and 75 per- 

 cent of its yield strength. 



Stainless steels 20Cb and 18Cr-14Mn-0.5N were not susceptible to 

 stress corrosion cracking in seawater at either the 2,500- or the 6,000- 

 foot depths. 



Of the stainless steels tested only 3 precipitation hardening 

 steels failed by stress corrosion cracking, 631 in the TH1050 and RH1050 



14 



