Titanium grade 2 is an unalloyed titanium which has small traces of carbon, oxygen, nitrogen, hydrogen and iron with UNS designation R50400. Titanium grade 7 is a typical titanium alloy consisting of unalloyed titanium plus  0.12% to 0.25% palladium with UNS designation R52400. It has the nominal composition of Ti-0.15Pd. Both grade 7 titanium and grade 2 titanium have excellent resistance to an extensive range of chemical corrosives. Especially, grade 7 titanium, as a palladium-containing  alloy, extends the range of titanium application in hydrochloric, phosphoric, and sulfuric acid solutions. The corrosion rates in different chemical solutions for titanium Gr.2 and Gr.7 are compared in below tables, respectively.

Solution	Concentration	Temperature		Corrosion Rate for Ti Gr.7(Ti-Pd)		Corrosion Rate for Ti Gr.2
-	%	°C	°F	mm/yr	mils/yr	mm/yr	mils/yr
Aluminum Chloride	10	100	212	< 0.025	< 1.00	< 0.025	< 1.00
Aluminum Chloride	25	100	212	0.025	1.00	50	2020

*Comparative corrosion rates for Ti Gr.2 and Gr.7 in aluminum chloride solution.

Corrodent	Concentration	Temperature		Corrosion Rate for Ti Gr.7(Ti-Pd)		Corrosion Rate for Ti Gr.2
-	%	°C	°F	mm/yr	mils/yr	mm/yr	mils/yr
Wet chlorine	-	room	room	< 0.025	< 1.00	< 0.025	< 1.00

*Comparative corrosion rates for Ti Gr.2 and Gr.7 in contact with wet chlorine.

Corrodent	Concentration	Temperature		Corrosion Rate for Ti Gr.7(Ti-Pd)		Corrosion Rate for Ti Gr.2
-	%	°C	°F	mm/yr	mils/yr	mm/yr	mils/yr
Citric acid	50	boiling	boiling	< 0.025	< 1.00	0.40	17.0

*Comparative corrosion rates for Ti Gr.2 and Gr.7 in citric acid solution.

Corrodent	Concentration	Temperature		Corrosion Rate for Ti Gr.7(Ti-Pd)		Corrosion Rate for Ti Gr.2
-	%	°C	°F	mm/yr	mils/yr	mm/yr	mils/yr
HCl(N2 saturated)	3	190	374	0.025	1.00	> 28	>1120
HCl(N2 saturated)	5	190	374	0.10	4.0	> 28	>1120
HCl(N2 saturated)	10	190	374	8.8	350	> 28	>1120
HCl(N2 saturated)	15	190	374	40	1620	-	-
HCl(O2 saturated)	3	190	374	0.13	5.0	> 28	>1120
HCl(O2 saturated)	5	190	374	0.13	5.0	> 28	>1120
HCl(O2 saturated)	10	190	374	9.2	368	> 28	>1120
HCl	5	Boiling	Boiling	0.18	7.0	> 10	> 400

*Comparative corrosion rates for Ti Gr.2 and Gr.7 in hydrochloric acid solutions saturated with N₂, saturated with O₂, and its pure, respectively.

Corrodent	Concentration	Temperature		Corrosion Rate for Ti Gr.7(Ti-Pd)		Corrosion Rate for Ti Gr.2
-	%	°C	°F	mm/yr	mils/yr	mm/yr	mils/yr
Sodium chloride	brine	93	200	< 0.025	< 1.00	-	-
Sodium chloride	10	190	374	< 0.025	< 1.00	-	-
Sodium chloride	23	boiling	boiling	-	-	nil	nil

*Comparative corrosion rates for Ti Gr.2 and Gr.7 in sodium chloride solutions.

Corrodent	Concentration	Temperature		Corrosion Rate for Ti Gr.7(Ti-Pd)		Corrosion Rate for Ti Gr.2
-	%	°C	°F	mm/yr	mils/yr	mm/yr	mils/yr
Sulfuric acid(N2 saturated)	1	100	212	-	-	7	282
Sulfuric acid(N2 saturated)	1	190	374	0.13	5.0	-	-
Sulfuric acid(N2 saturated)	5	100	212	-	-	26.5	1060
Sulfuric acid(N2 saturated)	5	190	374	0.13	5.0	-	-
Sulfuric acid(N2 saturated)	10	190	374	1.50	39	-	-
Sulfuric acid	5	boiling	boiling	0.5	20	48	1920

*Comparative corrosion rates for Ti Gr.2 and Gr.7 in sulfuric acid saturated with N₂ and its pure.

Corrodent	Concentration	Temperature		Corrosion Rate for Ti Gr.7(Ti-Pd)		Corrosion Rate for Ti Gr.2
-	%	°C	°F	mm/yr	mils/yr	mm/yr	mils/yr
Formic acid	50	boiling	boiling	0.075	3.0	3.6	143
Oxalic acid	1	boiling	boiling	1.13	45	45	1800
Phosphoric acid	50	70	158	1.8	71	10	405
Phosphoric acid	10	Boiling	Boiling	3.2	127	11	439

*Comparative corrosion rates for Ti Gr.2 and Gr.7 in formic acid, oxalic acid, and phosphoric acid solutions.