The dissolved titanium ion Ti⁴⁺ has significant inhibiting effect on corrosion rate of unalloyed titanium in boiling nitric acid solutions. The tabulated values in below table show the corrosion rates of titanium (either Grade 1, 2, 3 or 4) with various titanium ion addition in 40% and 68% boiling HNO₃, respectively.

Corrosion Rate
Titanium Ion Added	40% Nitric Acid		68% Nitric Acid
mg/L	mm/yr	mils/yr	mm/yr	mils/yr
0	0.75	29.5	0.81	32
10	-	-	0.02	0.8
20	0.22	8.7	0.06	2.4
40	0.05	2	0.01	0.4
80	0.02	0.8	0.01	0.4

*Corrosion data in accordance with ASM Handbook Volume 13.