ArcelorMittal USA

Plate
9% Nickel Steel: For use at cryogenic temperatures

Introduction
Iron, carbon steel and most ferritic alloy steels undergo a change
from ductile to brittle behavior through a temperature range which
varies with chemistry, heat treatment and thickness. This natural
characteristic of most ferritic materials prevents their use for pres-
sure vessels below approximately –150ºF(-101ºC). However, more
than 50 years ago, the International Nickel Company laboratories
found that a low-carbon 9% Nickel alloy steel, when appropriately
heat treated, retained notch ductility at temperatures to
–320ºF(-196ºC) and below.

9% Nickel steel has been recognized by the ASME Code for cryogen-
ic use since 1954 and has been widely used for storage of oxygen,
nitrogen and other liquefied gases in competition with stainless steel,
other austenitic alloys and aluminum.

Chemical Composition Heat Treatment

ArcelorMittal USA 9% Nickel steel is heat treated either by double
Element (%) A353 and A553 Type 1 normalizing and tempering (NNT) or quenching and tempering
Carbon (max.) .13 (Q&T). The tempering is conducted within a restricted range, that
Manganese (max.) .90
results in the formation of a small amount (5-15%) of metallurgically
Phosphorus (max.) .035
stable retained austenite, which is very important in developing the
Sulfur (max.) .035
Silicon .15/.40
superior cryogenic toughness of the steels.
Nickel 8.50/9.50

Specifications and Codes Heat Treatments for 9% Nickel Steel

Material specifications for ArcelorMittal USA 9% Nickel plate (UNS Double normalized and tempered (A353) 1650ºF + 1450ºF + (1050-1125ºF)
K81340) intended for cryogenic pressure vessels are ASTM A353 899ºC + 788ºC + (566 - 607ºC)
(double normalized); ASTM A553 Type I (quenched and tempered); Quenched and tempered (A553) 1475ºF + (1050 – 1125ºF)
802ºC + (566 - 607ºC)
ASME Section II, Part A, SA353 and SA553; and API Standard 620
Appendix Q, A353 and A553. ArcelorMittal USA also manufactures
9% nickel plate to DIN 17280 X8Ni9 (1.5662) in accordance with Size Availability
AD-Merkblatt W0/TRD 100 and certified with European Pressure ArcelorMittal USA provides a wide range of plate sizes for 9% Nickel
Equipment Directive PED 97/23/EC. plate steel. Thicknesses from .1875 to 2 in. (4.8 to 51 mm),
widths to 132 in.(3.4 m), and lengths to 540 in. (13.7 m) are
Rules for design, fabrication and testing of pressure vessels are given available depending on grade and property requirements. Consult
by the ASME Code Section VIII, Divisions 1 and 2 (including applica- ArcelorMittal USA for sizes outside these ranges, in particular widths
ble Code Cases 2214, 2335 and 2345), Section III Class 3 Compo- to 186 in. (4.7 m).
nents, and API Standard 620 Appendix Q.
Mechanical Properties Selected Property Information
Over the years, the properties of 9% nickel steels have evolved as
Tensile Properties (ASTM, ASME, API Requirement) a function of the technology in melting and refining used to pro-
duce them. The improvements enabled designers to raise minimum
Tensile Strength Yield Strength ksi Elongation in 2"
ksi [MPa] [MPa], min. [50mm](%) material requirements to take advantage of the increased properties,
(S)A353/ 100 - 120 75 [515] 20 and in particular toughness, to enhance their specifications. Today,
(S)A353M [690 – 825] while many of the standard requirements remain the same, many
(S)A553/ 100 – 120 85[585] 20 worldwide specifications are requiring improved Charpy-V notch
(S)A553M Type I [690 – 825] performance, such as 75 ft-lbs (100J) at minus 320ºF(-196ºC),
a level that heretofore would not have been achievable. These en-
hanced requirements can be achieved with clean steel technological
Recommended Radius for Cold Bending (A20/A20M) advances, as illustrated below. The benefit of lower carbon, sulfur,
Ratio of Bend Diameter phosphorus and higher nickel levels is shown with the improvement
Thickness of Material To Thickness of Specimen in toughness. ArcelorMittal USA 9% nickel steel can be ordered with
1 in. [25 mm] and under 1.5 0.002% S and 0.005% P maximums when required.
Over 1 in. [25 mm] to 2 in. [50 mm] incl. 2-1/2
Over 2 in. [50 mm] 3
9% Nickel Steel
Process Improvements
Mandatory Impact Properties – Charpy V-Notch
ASTM*, ASME* and API Requirement – Lateral Expansion Toughness (Transverse Average)
Phases % C % S % P % Ni Tested at -320ºF (-196ºC)
0.015 in. [0.381 mm] Transverse orientation (axis of notch
at –320ºF(-196ºC) parallel to major rolling direction)
I .10 .015 .015 8.7
* The Charpy V-Notch energy absorption values, as well as fracture appearance in
percentage shear, are required to be recorded by ASME Code, Section VIII, Division II .08 .010 .010 8.9
1 and Division 2, and Section III.

III .06 .005 .008 9.1

API Requirement – Charpy V-Notch Impact Values 3
IV .04 .001 .005 9.1
Transverse Value Longitudinal Value
Required 1 Required 1 ft-lbs., mils 0 50 100 150
Energy
Size of Specimen (Minimum Single Value) 2 (Minimum Single Value) 2 J 0 68 136 203
(mm) ft-lb [J] ft-lb [J] LE
mm 0 1.27 2.54 3.81
10 x 10 20 (16) [27(22)] 25 (20) [34(27)]
10 x 5.0 10 (8) [14(11)] 13 (10) [17(14)]
Other factors contribute to the improved toughness of 9% nickel
1
Average of three specimens
steels. Traditionally, toughness improves with quenched and tem-
2
Only one specimen of a set pered material over that produced in the normalized condition. Cool-
3
Subsized specimens use ratio of size ing rate plays a major role in determining Charpy toughness for 9%
nickel steels. Experimental work has shown that lateral expansion and
the ratio of yield to tensile for A353 and A553 are directly correlat-
ASTM Added Supplementary Requirements & ASME ed, and the higher the yield to tensile ratio, the more lateral expan-
Supplementary Requirements sion is expected. This is shown in the figures below. Consideration
Charpy V-Notch Energy Absorption Requirement at must be given then to choosing A353, a NNT product with generally
–320ºF(-196ºC) (A353, SA353, A553, SA553) lower Y/T, or A553, a Q&T product with higher Y/T and considerably
Minimum Impact Value higher Charpy and lateral expansion values. The cooling rate has a
Impact Value Required Required major affect on the resultant yield to tensile ratio, as illustrated below
Orientation (Average of 3 Specimens) (One Specimen Only) in ArcelorMittal USA laboratory studies. This information may be
Longitudinal 25 ft-lbs. [34 J] 20 ft-lbs. [27 J] important when considering heat treatments other than as provided
Transverse 20 ft-lbs. [27 J] 15 ft-lbs. [20 J] from the steel mill.

9% Nickel – Page 2
 Yield/Tensile Ratio as a Function of Cooling Rate Physical Properties

1 Modulus of Elasticity
At 70ºF (21ºC) 27 x 106 psi (185,000 MPa)
0.9 At –320ºF (-196ºC) 30 x 106 psi (209,000 MPa)
Yield/Tensile Ratio

0.8
Mean Coefficient of Expansion
0.7 -320 to 70ºF (-196 to 21ºC) 4.9 x 10-6 in./in./ºF (8.8 x 10-6 K-1)
-200 to 70ºF (-129 to 21ºC) 5.5 x 10-6 in./in./ºF (9.9 x 10-6 K-1)
0.6 -100 to 70ºF (-73 to 21ºC) 5.9 x 10-6 in./in./ºF (10.6 x 10-6 K-1)
-100 to 200ºF (-73 to 200ºC) 6.2 x 10-6 in./in./ºF (11.2 x 10-6 K-1)
10 (5.5) 100 (55) 1000 (555) 10000 (5555)
Cooling Rate from 1450ºF (788ºC); ºF/min. (ºC/min.)
Thermal Conductivity
Thermal Conductivity
Variance of Lateral Expansion with Yield/Tensile Ratio Temp. ºF(ºC) Btu in/(hr ft2 ºF) [W/(m K)]
-320(-196) 91[13.1]
(mm) -296(-176) 112[16.1]
70 (1.8) -275)-170) 120[17.3]
60 (1.5) -243(-153) 134[19.3]
Lateral Expansion (mils)

50 (1.3) -189(-122) 149[21.0]

40 (1.0) -99(-72) 172[24.8]
-9(-22) 190[27.4]
30 (.76)
81(27) 203[29.2]
20 (.51) 261(128) 226[32.5]
10 (.25) 441(228) 236[34.0]
0 621(328) 238[34.3]
801428) 232[33.4]
0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95
981(528) 224[32.3]
Yield/Tensile Ratio
Air Cool Accelerate Cool Quench
Fabrication
For general fabrication information refer to “Guidelines for Fabricat-
Design and Engineering Data ing and Processing Plate Steel”.

Cutting
Maximum Allowable Stress Value – Welded
ArcelorMittal USA 9% Nickel is flamecut very much like mild steel,
(-20 to 100ºF)[-29 to 38ºC]
employing only minor adjustments of fuel and oxygen. The steel is
Section VIII Section VIII Section III characterized by having an adherent scale. This should be popped
Division 11 Division 2 Class 3 API 620 off prior to setting the cut in order to avoid clogging the tip. Pre-
(S)A353/A553 28.6 ksi 33.3 ksi 28.6 ksi Based on weld
heating for cutting is generally unnecessary.
(197 MPa) (230 MPa) (197 MPa) metal strength
27.1 psi 31.7 ksi
(187 MPa) * (219 MPa)* Because of its high strength and toughness, the thickness, which can
be sheared by a given machine, will be approximately 2/3 of that of
1
Section VIII Division 1 provides for the use of higher allowable stresses in tension mild steel. Rake angles higher than those of mild steel are advanta-
at low temperatures. Consult Table ULT-23 for specifics.
geous.
* Welded, with the tensile strength of the Section IX reduced tension test less than
100 ksi (690 MPa), but not less than 95 ksi (655 MPa)

9% Nickel – Page 3
Forming Welding
In most circumstances, it is desirable to cold form rather than Welding Qualification 9% Nickel steel welding procedures are quali-
hot form this steel, whether double normalized and tempered or fied under Section IX of the ASME Code. For qualification purposes,
quenched and tempered. It should be noted that 9% Nickel steel the double normalized (A353) and quenched grades (A553) are
has a high yield strength and requires approximately three times the P-No. P11A Group 1. Additional tension tests at or below the vessel
forming capacity of mild steel. minimum allowable temperature are required for Section VIII Div 1
ULT applications.
It is advisable to round-off corners in tension and smooth, rough cut
edges. Section VIII, Divisions 1 and 2, Section III and API Standard 620
Appendix Q specify that the weld metal and heat affected zone of
The following bending limits are suggested: procedure qualification tests shall meet the Charpy V-Notch require-
ments for the plate. Production impact testing may be exempt for
Die Span: 12 x Thickness welding under certain conditions in Section VIII, and for API 620 Ap-
pendix Q after the initial tank construction.
Plate Thickness Min. Radius
To 3/4 in. [19 mm] 4 x thickness
Energy Input As with other low temperature steels, the welding en-
Over 3/4 in. to 1-1/4 in. [31 mm] 5 x thickness
Over 1-1/4 in. [31 mm] to 2 in. [50 mm] 6 x thickness
ergy input for ArcelorMittal USA 9% Nickel steel must be controlled
to preserve notch toughness in the heat affected zone.

Generally, the steel is welded at low energy inputs – even sub-

For roll forming: minimum inside diameter = 30 x thickness
merged-arc welds with Inconel are best made with 1/16 in.
(1.6mm) wire. However, caution is advised for plate under about 0.5
The ASME Code requires post heat treatment where outer fiber
in.(13mm) both because light plate chills the weld less rapidly and
elongation in cold forming exceeds 5% by the formula:
because transverse plate Charpy values tend to be lower initially for
thin plate.

% E = (70 x t) x (1 – Rf/R0) Data from laboratory tests suggest the following guide for preparing
Rf the qualification test plate.

% E – percent extreme fiber elongation Approximate Thickness Kilojoules/in.(KJ/mm), max.

9/16 in. [14 mm] and under 35(1.4)
t – plate thickness
Over 9/16 in. [14 mm] to 40(1.6)
Rf – final radius 3/4 in. [19 mm]
Ro – original radius (equals infinity for flat plate) 3/4 in. [19 mm] and over 50(2.0)

Note: 9% Nickel is seldom welded at over 50 KJ/in.(2.0 KJ/mm) in any thickness.

In addition, cold forming of 9% Nickel steel may cause the transfor-
mation of retained austenite into untempered martensite due to cold
work. This may have a deleterious effect on toughness, but may be
partially restored by an intercritical post heat treatment. Fabricators Preheat Joints in ArcelorMittal USA 9% Nickel steel made with aus-
are urged to determine the effect of forming practices on final mate- tenitic weld metals are relatively immune to cold cracking difficulties.
rial properties. Nevertheless, it is suggested that plate over 1in.(25mm) in thickness
be preheated to about 100ºF(35ºC) and that lighter plate not be
The post heat treatment, where necessary, is conducted in accor- welded below the dew point. Section VIII Code Case 2214 provides
dance with the rules of Section VIII Division 1 UHT-56 within the additional information on preheat requirements in special situations.
range of 1025-1085ºF(551-583ºC), but not exceeding the tem-
pering temperature, holding at temperature for one hour per inch of
thickness, followed by cooling at a rate no less than 300ºF(167ºC)
per hour. Slower cooling rates may reduce the notch toughness of
the steel.

In some cases, it may be desirable to form hot. The formed part

must be either completely reheat treated or in the case of the double
normalized and tempered specification, A353, the forming opera-
tion may be conducted at 1650 - 1750ºF(899-954ºC) and treated
as the first normalizing operation. The ASME Code requires that
tests be made by the fabricator to verify the heat treatment. It is
suggested that hot forming be limited to non-welded plate, unless
it is first demonstrated that the weld metal is capable of meeting
required mechanical properties after being heat treated.

9% Nickel – Page 4
Special Precautions Because of its high nickel content, 9% Nickel In submerged-arc welding of ArcelorMittal USA 9% Nickel steel, par-
steel is susceptible to the retention of magnetism of enough inten- ticularly of thick plate and restrained joints, it is desirable to use low
sity and permanence to affect arc welding. Care should be taken in energy inputs to avoid the possibility of hot cracking of weld beads,
exposing the plate to lifting magnets or to strong direct current fields particularly the initial ones in the groove. With both the submerged-
after the austenitizing heat treatments. ArcelorMittal USA 9% Nickel arc and MIG processes used at high energy inputs, the fabricator
steels are handled without magnets in the finishing operations. As should be careful to establish by procedure tests that the desired
a added insurance, when requested, ArcelorMittal USA can furnish weld strength (usually 95 ksi (655 MPa)) can be attained.
its plates demagnetized to a maximum residual level of 50 gauss as
measured on the plate edges. Post Weld Heat Treatment Except as provided by the fabrication
requirements of ULT-79, the ASME Code requires no post weld heat
Once induced, magnetism may be reduced or removed by wrapping treatment for 9% Nickel up to 2 in.(51 mm)inclusive in thickness.
or sweeping with alternating current cables or electromagnets. For See AF630.1 (Division 2) and UHT56 (Division 1). Where post weld
heavy plate, it may be necessary to use special demagnetizing equip- heat treatment is performed, it is necessary to control the tem-
ment that utilize decreasing and reversing currents strong enough perature within the range of 1025-1085ºF (551-583ºC) but not
to realign any magnetic domain fields to neutral. In extreme cases, over the tempering temperature and to cool at a rate not less than
residual magnetism can be removed by reheat treating. 300ºF(167ºC) per hour to avoid possible reduction in notch tough-
ness of the steel.
Shielded Metallic Arc Welding with alternating current and inter-
rupted-arc MIG welding are less affected by magnetism than other Further Information
processes. Isolated magnetic poles at the seam may be temporarily Contact ArcelorMittal USA (Jerry Shick) at +1 610 383 2589 or
neutralized by strong permanent magnets. Care should be taken, email: jerry.shick@arcelormittal.com
particularly in MIG welding, that magnetic shop dirt adhering to weld
chamfers does not lead to weld porosity. Continuing updates of this information can be found on our website
at: http://www.arcelormittal.com

All information in this brochure is for the purpose of information only. ArcelorMittal USA reserves the right to change its product range at any time without prior notice.

ArcelorMittal USA ArcelorMittal USA ArcelorMittal USA

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www.arcelormittal.com www.arcelormittal.com December 2010