Inconel® 600 is a nickel-base alloy with excellent carburization, and good oxidation resistance at elevated temperatures. The alloy has long been used in the heat treating industry for many of the same applications as RA330®. 600 has useful resistance to dry Cl2 and HCl gases at moderately elevated temperatures. Alloy 600 is not suggested for use at red heat when sulfur is present due to elevated nickel quantities. Grades 200 and 201 nickel are normally preferred for handling concentrated, high temperature caustic. However, when sulfur compounds are present as well, or for ammonium hydroxide service, 600 alloy is suggested. 600 alloy is subject to stress corrosion cracking in hot, concentrated caustic alkalis. To avoid stress corrosion cracking, the 600 alloy fabrication should be fully stress relieved prior to use. A minimum treatment of 1650°F for 1 hour is suggested, but 1800-1850°F for 1 hour preferred.