Green death explained

Green death is a solution used to test the resistance of metals and alloys to corrosion. It consists of a mixture of sulfuric acid, hydrochloric acid, iron(III) chloride and copper(II) chloride and its boiling point is at approximately 103 °C. Its typical chemical composition is given in the table hereafter:^{[1] [2] [3] [4]}

Chemical composition of the green death solution!Reagent(—)!Formula(—)!Usually(wt. %)!Min(wt. %)!Max(wt. %)

Sulfuric acid		11.9	11.5	11.9
Hydrochloric acid	HCl	1.3	1.2	1.3
Iron(III) chloride		1.0	1.0	1.0
Copper(II) chloride		1.0	1.0	1.0

The chemical composition of the green death solution allows it to achieve a particularly aggressive oxidizing chloride solution. Indeed, among the four reagents, all are oxidizing species except hydrochloric acid (HCl) in which the chlorine atom is present in its lowest oxidation state as anion. The chloride anions, also added to the solution as counter-ions of iron(III) and copper(II) species, are very aggressive for the localized corrosion of metals and alloys as they induce severe pitting corrosion problems. The green death solution is also used to determine the critical pitting temperature (CPT) and the critical crevice temperature (CCT) of metals and alloys.

Notes and References

1. Web site: What is Green Death? – Definition from Corrosionpedia . Corrosionpedia . Corrosionpedia . 14 November 2016 . 10 September 2021 .
2. Web site: Resistance to pitting and crevice corrosion of Hastelloy C-276 . Haynes International . Haynesintl.com . 10 September 2021 .
3. Web site: Inconel alloy C-276 . Specialmetals.com . Specialmetals.com . 10 September 2021 .
4. Mottu, Nathalie (2016). URTM66, 02/2016, Industeel ArcelorMittal.