Open AccessEffect of soluble zinc additions on the SCC performance of nickel alloys in deaerated hydrogenated water
Author(s) -
David Alexander Vodden Morton,
C.D. Thompson,
D. Gladding,
M.K. Schurman
Publication year - 1997
Language(s) - English
Resource type - Reports
DOI - 10.2172/319774
Subject(s) - zinc , metallurgy , materials science , nickel , spinel , alloy , paris' law , corrosion , growth rate , composite material , crack closure , fracture mechanics , geometry , mathematics
Stress corrosion crack growth rates (SCCGR) of alloy 600, EN82H and X-750 were measured in deaerated hydrogenated water to determine if soluble zinc mitigates SCCGR. Constant load compact tension specimen tests were conducted. Two test strategies were used to discern a possible zinc effect. The first strategy employed separate SCCGR tests in zinc and non-zinc environments and compared the resulting crack growth rates. The second strategy varied zinc levels at the midterm of single specimen SCCGR tests and characterized the resulting crack growth rate effect through an electrical potential drop in-situ crack monitor. Results from the direct comparison and midterm changing chemistry tests did not discern a zinc influence; any apparent zinc influence is within test to test variability ({approximately}1.5{times} change in crack growth rate). AEM, AUGER and ESCA crack tip fracture surface studies identified that zinc was not incorporated within crack tip oxides. These studies identified nickel rich crack tip oxides and spinel, with incorporated zinc, ({approximately}5 atom percent) bulk surface oxides