Alloy 20

A nickel-iron-chromium grade, Alloy 20 is ideal for a wide range of corrosive environments.

With the addition of copper, molybdenum and niobium, Alloy 20 is the alloy of choice for sulphuric acid applications.

Inventory

Product form	Size range from	Size range to
Alloy 20 sheet & plate	1.6 mm	76.2 mm
Alloy 20 round bar	10 mm	279.4 mm
Alloy 20 pipe	0.5 in	10 in
Alloy 20 pipe fittings	0.5 in	10 in
Alloy 20 flanges	0.5 in	10 in

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Flanges
Pipe Fittings
Pipe
Sheet & Plate
Round Bar

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Chemical Analysis

%	Ni	Cr	Mo	Mn	Cu	Si	C	S	P	Nb+Ta	Fe
Min	32.5	19	2	-	3	-	-	-	-	8.0 x C 1.0	-
Max	35	21	3	2	4	1	0.06	0.035	0.035	-	Balance

Applications

Perfect for applications in the Chemical Processing Industry

Alloy 20 can be used in a variety of applications including:

Sulphuric acid pickling tanks, racks and heating coils
Phosphate coating drums and racks
Heat exchangers
Process piping
Tanks
Pumps and valves
Gaskets
Mechanical seals
Process equipment for manufacture of bullet-proof fibre, Kevlar

About Alloy 20

Alloy 20 contains niobium for stabilization which enhances its corrosion resistance. The alloy is an iron-base, austenitic alloy with excellent corrosion resistance to a wide range of media.

With the high nickel content, Alloy 20 shows good resistance to chloride-induced stress corrosion cracking. In addition the alloy also has good resistance to pitting and crevice corrosion.

In the chemical process market, key applications of Alloy 20 are in sulphuric, phosphoric and nitric acid environments.

The alloy is also commonly used in the food industry for the manufacture of food preservatives (phosphorus oxychloride and phosphorus trichloride).

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Properties

Density:: 7.695 g/cm³ annealed
Melting range:: 1385-1443°C
Electrical resistivity:: 1.08 x 10^-6 Ω⋅m
Poisson's Ratio:: 0.31

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Mechanical & Physical Properties
Aqueos Corrosion Data

Mechanical & Physical Properties	21.1°C	49.4°C	100°C	150°C	200°C	300°C	350°C	400°C	450°C	500°C	900°C
Ultimate Tensile Strength /MPa	551.6	-	-	-	-	-	-	-	-	-	-
0.2% Yield Strength /MPa	241.3	-	-	-	-	-	-	-	-	-	-
Reduction of area % (for bar)	50	-	-	-	-	-	-	-	-	-	-
Elongation %	30	-	-	-	-	-	-	-	-	-	-
Coefficient of Thermal Expansion µm/m⁰C	-	-	14.7	14.9	15.1	15.5	15.7		15.9	16	17.2
Thermal Conductivity /kcal/(hr.m.°C)	-	125.9	135.1		153.3	169.6		187.5

Media	Common Name	Temp °F (°C)	Corrosion Rate (mpy)
5% CH³CO²H w/Air	Acetic Acid	70 (21)	40
10% CH³CO²H	Acetic Acid	86 (30)	3.4
56% CH³CO²H	Acetic Acid	176 (80)	66
85% CH³CO²H w/Air	Acetic Acid	70 (21)	400
98% CH³CO²H	Acetic Acid	241 (116)	12
50% NaOH	Caustic Soda	195 (90)	0.55
50% NaOH	Caustic Soda	310 (155)	0.5
75% NaOH	Caustic Soda	250 (120)	1.0
90% CH²O²	Formic Acid (Liquid)	70 (21)	4
90% CH²O²	Formic Acid (vapour)	70 (21)	7
1% HCL	Hydrochloric Acid	214 (101)	680
10% HCL	Hydrochloric Acid	86 (30)	80
10% HCL	Hydrochloric Acid	221 (105)	8000
10% HNO³	Nitric Acid	216 (102)	12000
10% H³PO⁴	Phosphoric Acid	75 (24)	0.6
10% H³PO⁴	Phosphoric Acid	214 (101)	154
40% H³PO⁴	Phosphoric Acid	75 (24)	1
500ppm NaClO	Sodium Hypochlorite	77 (25)	0.8
2% H²SO⁴	Sulphuric Acid	70 (21)	2
5% H²SO⁴	Sulphuric Acid	140 (60)	10
5% H²SO⁴ w/Air	Sulphuric Acid	86 (30)	61
19% H²SO⁴	Sulphuric Acid	223 (106)	110
20% H²SO⁴	Sulphuric Acid	70 (21)	4
50% H²SO⁴ w/Air	Sulphuric Acid	86 (30)	16
5% H²SO⁴	Sulphuric Acid	255 (124)	1000
93% H²SO⁴ w/Air	Sulphuric Acid	86 (30)	10

Mechanical & Physical Properties

Mechanical & Physical Properties	21.1°C	49.4°C	100°C	150°C	200°C	300°C	350°C	400°C	450°C	500°C	900°C
Ultimate Tensile Strength /MPa	551.6	-	-	-	-	-	-	-	-	-	-
0.2% Yield Strength /MPa	241.3	-	-	-	-	-	-	-	-	-	-
Reduction of area % (for bar)	50	-	-	-	-	-	-	-	-	-	-
Elongation %	30	-	-	-	-	-	-	-	-	-	-
Coefficient of Thermal Expansion µm/m⁰C	-	-	14.7	14.9	15.1	15.5	15.7		15.9	16	17.2
Thermal Conductivity /kcal/(hr.m.°C)	-	125.9	135.1		153.3	169.6		187.5

Aqueos Corrosion Data

Media	Common Name	Temp °F (°C)	Corrosion Rate (mpy)
5% CH³CO²H w/Air	Acetic Acid	70 (21)	40
10% CH³CO²H	Acetic Acid	86 (30)	3.4
56% CH³CO²H	Acetic Acid	176 (80)	66
85% CH³CO²H w/Air	Acetic Acid	70 (21)	400
98% CH³CO²H	Acetic Acid	241 (116)	12
50% NaOH	Caustic Soda	195 (90)	0.55
50% NaOH	Caustic Soda	310 (155)	0.5
75% NaOH	Caustic Soda	250 (120)	1.0
90% CH²O²	Formic Acid (Liquid)	70 (21)	4
90% CH²O²	Formic Acid (vapour)	70 (21)	7
1% HCL	Hydrochloric Acid	214 (101)	680
10% HCL	Hydrochloric Acid	86 (30)	80
10% HCL	Hydrochloric Acid	221 (105)	8000
10% HNO³	Nitric Acid	216 (102)	12000
10% H³PO⁴	Phosphoric Acid	75 (24)	0.6
10% H³PO⁴	Phosphoric Acid	214 (101)	154
40% H³PO⁴	Phosphoric Acid	75 (24)	1
500ppm NaClO	Sodium Hypochlorite	77 (25)	0.8
2% H²SO⁴	Sulphuric Acid	70 (21)	2
5% H²SO⁴	Sulphuric Acid	140 (60)	10
5% H²SO⁴ w/Air	Sulphuric Acid	86 (30)	61
19% H²SO⁴	Sulphuric Acid	223 (106)	110
20% H²SO⁴	Sulphuric Acid	70 (21)	4
50% H²SO⁴ w/Air	Sulphuric Acid	86 (30)	16
5% H²SO⁴	Sulphuric Acid	255 (124)	1000
93% H²SO⁴ w/Air	Sulphuric Acid	86 (30)	10

Specifications

UNS Number:: N08020
Werkstoff Number:: 2.4660
Standards:: ASTM A240, B463, B473, B366, B464, B468, B462, B729, B775

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