Nitronic 50

Nitronic 50

Nickel (Ni) - 12.5 Median
(11.5 Min - 13.5 Max)
Chromium (Cr) - 22 Median
(20.5 Min - 23.5 Max)
Molybdenum (Mo) - 2.25 Median
(1.5 Min - 3.0 Max)
Iron (Fe) - 57.19 Balance
Manganese (Mn) - 5.0 Median
(4.0 Min - 6.0 Max)
Silicon (Si) - 1.0 Max
Other

Key

Nickel
Copper
Chromium
Aluminum
Molybdenum
Iron
Titanium
Manganese
Cobalt
Other
  • Nickel (Ni) 12.5 Median
    (11.5 Min - 13.5 Max)
  • Chromium (Cr) 22 Median
    (20.5 Min - 23.5 Max)
  • Molybdenum (Mo) 2.25 Median
    (1.5 Min - 3.0 Max)
  • Iron (Fe) 57.19 Balance
  • Manganese (Mn) 5.0 Median
    (4.0 Min - 6.0 Max)
  • Carbon (C) 0.06 Max
  • Silicon (Si) 1.0 Max

UNS S20910, XM19

Nitronic 50 is a durable austenitic stainless steel used for anti-galling applications with greater corrosion resistance than 304 or 316 stainless steel with nearly twice the yield strength. It has excellent mechanical properties at low and high-temperature ranges. Nickel Systems stocks threaded rod/studs and nuts in Nitronic 50 ranging from 1/2”-13 to 3/4”-10 in both finished and heavy pattern certified to ASTM A194 Grade 8r. Most designs of a gall-resistant joint require only one component to be gall resistant.

Summary

  • Environment:
    Moderately Corrosive: Acids & Chemicals
  • Temperature Limit:
    1200 °F / 649 °C
  • Ultimate Tensile (Typical):
    100 ksi / 689 mpa

Specifications & Technical Data

If your question isn’t answered below, download the technical data sheet here.

Specifications

  • Bolts: ASTM A193 & ASME SA193 GRADE B8R
  • Nuts: ASTM A194 & ASME SA194 GRADE 8R
  • Bar: ASTM A276 & A479
  • W-Nr 1.7440

Physical Properties

Physical Constants
Density, g/cm3 (lbs/in.3) 24 °C (75 °F) 7.88 (0.285)
Electrical Resistivity, µΩ•cm 21 °C (70 °F) 82

 

MAGNETIC PERMEABILITY IN NITRONIC 50 WIRE*
Condition Typical Magnetic Permeability at Field Strength of
50 Oer (3978 A/m)  100 Oer (7957 A/m) 200 Oer (15 914 A/m)
Annealed 1.004 1.004 1.004
Cold Drawn 27% 1.004 1.004 1.003
Cold Drawn 56% 1.004 1.004 1.004
Cold Drawn 75% 1.004 1.004 1.004

*Average of duplicate tests on mill-annealed sheet samples using the Curie Force Method.

MAGNETIC SUSCEPTIBILITY IN MILL-ANNEALED NITRONIC 50 SHEET
Temperature, °C (°F) Magnetic Mass Susceptibility, χ, 10-6 cm3/g Typical Magnetic Permeability, µ
22 (72) 21.5 1.0021
-23 (-9) 22.5 1.0022
-73 (-99) 25.0 1.0025
-123 (-189) 28.5 1.0028
-173 (-279) 35.5 1.0035
-223 (-369) 54.0 1.0053
-240 (-400) 74.0 1.0073
-258 (-432) 61.0 1.0060

Note that the magnetic susceptibility of NITRONIC 50 peaks at approximately -240 °C (-400 °F). This phenomenon is independent of field strength.

Mechanical Properties

Minimum Properties Acceptable For Material Specification (Bars)
Condition Size, mm (in.) Ultimate Tensile Strength,  MPa (ksi) 0.2% Yield Strength,  MPa (ksi) Elongation % in 4D0 Reduction of Area, % Rockwell Hardness Max. Impact Strength and Lateral Expansion, -196 °C (-321 °F) Impact Strength -60 °C (-76 °F), J (ftlbs) Lateral Expansion -60 °C  (-76 °F), mm (in.)
J (ftlbs) mm (in.)
Annealed all 690 (100) 415 (60) 35 55 C35 27 (20) 0.381 (0.015) 20 (15) 0.381 (0.015)
HS 0 -50.8  (0 – 2) 930 (135) 800 (116) 20 50 C35 27 (20) no minimum guaranteed, but production aims for 0.381 mm min 20 (15) 0.381 (0.015)
HS > 50.8 – 76.2  (> 2 – 3) 800 (116) 515 (75) 25 50 C35 27 (20) 20 (15) 0.381 (0.015)
HS > 76.2 – 203.2 (> 3 – 8) 700 (102) 415 (60) 30 50 C35 27 (20) 20 (15) 0.381 (0.015)
SHS 0 – 50.8  (0 – 2) 930 (135) 800 (116) 25 50 C35 27 (20) 20 (15) 0.381 (0.015)
SHS > 50.8 – 145  (> 2 – 5.7) 900 (131) 725 (105) 25 50 C35 27 (20) 20 (15) 0.381 (0.015)

 

Typical Room Temperature Properties
Condition Size, mm (in.) UTS,  MPa (ksi) 0.2% YS,  MPa (ksi) Elongation  % in 4D0 Reduction  of Area, % Rockwell Hardness Max. Impact Strength and Lateral Expansion, -196 °C (-321 °F) Impact Strength -60 °C  (-76 °F), J (ftlbs) Lateral Expansion -60 °C  (-76 °F), mm (in.)
J (ftlbs) mm (in.)
Annealed 25.4 (1) 25.4 (1) 827 (120) 414 (60) 50 70 B98 68 (50) >0.381 (0.015) >20 (15) >0.381 (0.015)
HS >50.8 (2) ≤101.6 (4) 937 (136) 731 (106) 33 66 C28 68 (50) >0.653 (0.026) >20 (15) >0.381 (0.015)
SHS >50.8 (2) ≤101.6 (4) 1009 (146) 830 (120) 27 63 C32 50 (37) >0.427 (0.017) >20 (15) >0.381 (0.015)

 

Typical Short-time Elevated Temperature Tensile Properties
Condition Test Temperature, °C (°F) UTS,  MPa (ksi) 0.2% YS,  MPa (ksi) Elongation  % in 4D0 Reduction  of Area, %
Annealed 1066 °C (1950 °F)
Bars 19.1 – 31.8 mm
(0.75 – 1.25 in.) Diameter
24  (75) 855 (124) 538 (78) 41 68
93  (200) 772 (112) 455 (66) 41 68
204  (400) 703 (102) 400 (58) 38 67
316  (600) 676    (98) 372 (54) 38 64
427  (800) 648    (94) 345 (50) 40 63
538 (1000) 614    (89) 331 (48) 37 63
649 (1200) 552    (80) 303 (44) 37 63
732 (1350) 469    (68) 290 (42) 43 72
816 (1500) 345    (50) 221 (32) 60 85
Annealed 1121 °C  (2050 °F)
Bars 25.4 – 38.1 mm
(1 – 1.5 in.)  Diameter
24  (75) 807 (117) 414 (60) 45 71
93  (200) 738 (107) 338 (50) 44 71
204  (400) 662    (96) 262 (38) 44 70
316  (600) 634    (92) 241 (35) 43 68
427  (800) 614    (89) 234 (34) 44 66
538 (1000) 579    (84) 221 (32) 41 67
649 (1200) 510    (74) 214 (31) 38 64
732 (1350) 455    (66) 214 (31) 37 62
816 (1500) 359    (52) 207 (30) 41 61

Average of triplicate tests from each of three heats.

Typical Stress-rupture Strength
Condition Test Temperature, °C (°F) Stress for Failure, MPa (ksi)
100 Hours 1,000 Hours 10,000 Hours (estimated)
Annealed 1066 °C
(1950 °F)
Bars 19.1 – 31.8 mm
(0.75 – 1.25 in.)
Diameter
538 (1000) 627 (91) 607 (88) 496   (72)
593 (1100) 496 (72) 427 (62) 324   (47)
649 (1200) 379 (55) 262 (38) 152   (22)
732 (1350) 145 (11) 82.7 (12) 41.4    (6)
816 (1500) 69.0 (10) 25.5 (3.7) 9.0  (1.3)
Annealed
1121 °C  (2050 °F)
Bars 25.4 – 38.1 mm  (1 – 1.5 in.) Diameter
538 (1000)
593 (1100) 488 (65) 372 (54) 296   (43)
649 (1200) 345 (50) 283 (41) 224 (32.5)
732 (1350) 200 (29) 103 (15) 58.6 (8.5)
816 (1500) 89.6 (13) 44.8 (6.5) 241  (3.5)

Average of tests from three heats.

Typical creep strength: 25.4 mm (1 in.) diameter bar
Condition Test Temperature, °C (°F) Stress for Min Creep Rate, MPa (ksi)
0.0001% per Hour 0.00001% per Hour
Annealed 1121 °C (2050 °F) 593 (1100) 283 (41) 238 (34.5)
649 (1200) 152 (22) 110 (16)

Test from one heat.

Typical mechanical properties: cold-drawn wire
Cold Reduction % UTS,  MPa (ksi) 0.2% YS,  MPa (ksi) Elongation % in 4D0 Reduction of Area, %
15 1138 (165) 986 (143) 23 56
30 1338 (194) 1200 (174) 15 49
45 1489 (216) 1351 (196) 11 45
60 1613 (234) 1489 (216) 9 42
75 1696 (246) 1613 (234) 8 39

Average of duplicate tests. Starting size 6.35 mm (0.25 in.) dia. rod annealed at 1121 °C (2050 °F).

Typical sub-zero mechanical properties: 25.4 mm (1 in.) diameter bar – annealed 1121 °c (2050 °f)
Test Temperature, °C (°F) UTS,  MPa (ksi) 0.2% YS,  MPa (ksi) Elongation % in 4D0 Reduction of Area, %
-73 (-100) 1007 (146) 586   (85) 50 65
-196 (-320) 1558 (226) 883 (128) 41 51

Average of duplicate tests.

Typical impact strength: 25.4 mm (1 in.) diameter bar
Test Temperature,  °C (°F) Impact – Charpy V. Notch, J (ftlbs)
Annealed at 1121 °C (2050 °F) Simulated HAZ
24 (75) 230 (170) 230 (170)
-73 (-100) 156 (115) 156 (115)
-196 (-320) 68  (50) 68 (50)

Heat treated at 677 °C (1250 °F) for 1 hour to simulate the heat-affected zone of heavy weldments. Average of duplicate test.

Effect of cold reduction on mechanical properties of bars
Diameter  Bar,  mm (in.) Cold  Reduction % UTS,  MPa (ksi) 0.2% YS,  MPa (ksi) Elongation  % in 4D0 Reduction of Area % Rockwell Hardness Charpy Impact, J (ftlbs)
Test Temperature, °C (°F)
27 (80) -40 (-40) -79 (-110)
19.05 (0.75) 0 804 (116.6)    397  (57.6) 47 71 B91 314 (232)
19.05 (0.75) 13 982 (142.5)

973 (141.1)

869 (126.0)
844 (122.5)
31
31
67
66
C30 157 (116)
156 (115)
16.51 (0.65) 28 1086 (157.6)
1076 (156.0)
1058 (153.4)
1036 (150.6)
2124 64
64
C34 133  (98)
123  (91)
100 (74)
73 (54)
19.05 (0.75) 46 1282 (185.9)
1263 (183.1)
1268 (183.8)
1245 (180.6)
18
16
58
58
C36 73  (54)
71  (53)
65 (48)
58 (43)
51 (38)
53 (39)

 

Fatigue Strength

ROTATING BEAM FATIGUE TESTS
Condition Bar Diameter, mm (in.) Fatigue Strength at 108 Reversals of Stress, MPa (ksi)
Tested in Air* Tested in Seawater**
Annealed 1121 °C (2050 °F) 25.4 (1) 290 (42) 152 (22)
Annealed 1066 °C (1950 °F) 25.4 (1) 324 (47)
High-Strength (HS) Bars (Hot Rolled Unannealed) 25.4 (1) 469 (68) 124 (18)
63.5 (2.5) 400 (58) 103 (15)
102 (4 303 (44) 103 (15)

*R R Moore specimens tested at room temperature.    ** McAdam specimens tested in ambient temperature seawater (11 – 31 °C) at LaQue Corrosion Laboratory Wrightsville Beach, N.C. Tests from one heat for each size and condition.

SHEAR STRENGTH
Condition UTS, MPa (ksi) Double Shear, MPa (ksi) Shear/Tensile Ratio, %
Annealed 1066 °C (1950 °F) 869 (126) 598 (86.8) 69
Annealed 1121 °C (2050 °F) 779 (113) 541 (78.5) 69.5

Average of duplicate tests.

ELASTIC PROPERTIES AT ROOM TEMP.
Modulus of Elasticity in Tension (E), GPa (Mpsi) Modulus of Elasticity in Torsion (G), GPa (Mpsi) Poisson’s Ratio
199 (28.9) 74.5 (10.8) 0.312

Average of duplicate tests.

ELASTIC PROPERTIES AT ELEVATED TEMPERATURES
Temperature, °C (°F) Young’s Modulus in Tension Poisson’s Ratio
GPa Mpsi
22 (72) 199 28.9 0.312
93 (200) 192 27.8 0.307
149 (300) 186 27.0 0.303
204 (400) 180 26.1 0.299
260 (500) 174 25.3 0.295
315 (600) 170 24.6 0.291
371 (700) 165 24.0 0.288

Tests performed on sheet samples in the longitudinal direction using strain gauges.

NOTCH SENSITIVITY AT ROOM TEMP.
Condition UTS – Smooth, MPa (ksi) UTS – Notched, MPa (ksi)
Annealed 1121 °C (2050 °F) 790 (114.5) 1069 (155)
Annealed 1066 °C (1950 °F) 830 (120.5)
High-Strength (HS) bars 1041 (151.0) 1355 (196.5)

Average of duplicate tests using notched specimens with a stress-concentration factor of kt = 1.3. 

Thermal Properties

COEFFICIENT OF THERMAL EXPANSION ANNEALED MATERIAL*
Temperature, °C (°F) Coefficient of Thermal Expansion
µm/m/K μin./in./°F
21 – 93 (70 – 200) 16.2 9.0
21 – 204 (70 – 400) 16.6 9.2
21 – 316 (70 – 600) 17.3 9.6
21 – 427 (70 – 800) 17.8 9.9
21 – 538 (70 – 1000) 18.4 10.2
21 – 649 (70 – 1200) 18.9 10.5
21 – 760 (70 – 1400) 19.4 10.8
21 – 871 (70 – 1600) 20.0 11.1

*Average of duplicate tests.

THERMAL CONTRACTION
Temperature, °C (°F) Contraction Parts Per Million, (ppm) Mean Expansion Coefficient Between T and 24 °C (75 °F)
ppm/°C ppm/°F
-41 (-41) 948 14.61 8.17
-46 (-51) 1016 14.53 8.06
-51 (-60) 1074 14.34 7.95
-62 (-80) 1237 14.40 7.98
-73 (-100) 1398 14.43 7.99
-87 (-125) 1560 14.07 7.80
-101 (-150) 1723 13.80 7.66
-117 (-178) 1951 13.84 7.71
-129 (-200) 2079 13.60 7.56
-143 (-225) 2231 13.37 7.44
-162 (-260) 2333 12.55 6.96
-196 (-320) 2542 11.56 6.44

 

THERMAL CONDUCTIVITY
Temperature, °C (°F) Thermal Conductivity*, W/m/K (BTU/hr/ft/in./°F)
21 (70)
149 (300) 15.6 (108)
316 (600) 17.9 (124)
482 (900) 20.3 (141)
649 (1200) 23.0 (160)
816 (1500) 25.2 (175)

*Average of duplicate tests.

Galling and Wear Resistance

WEIGHT LOSS OF COUPLE MG/1000 CYCLES
Alloy (Rockwell Hardness) Versus Alloy K 500 (C34) NITRONIC 50 (C28) Type 316 NITRONIC 50 (B95)
Type 316 (B91) 33.78 10.37 12.51 (B91) 4.29
17-4 PH (C43) 34.08 12.55 18.50 (B91) 5.46
Cobalt Alloy 6B (C48) 18.78 3.26 5.77 (B72) 1.85
Type 431 (C42) 26.40 6.73 5.03 (B72) 3.01
Ti-6AI-4V (C36) 17.19 6.27 6.31 (B72) 4.32
Alloy K-500 (C34) 30.65 34.98 33.78 (B91) 22.87
NITRONIC 50 (C28) 34.98 9.37 10.37 (B72) 4.00
NITRONIC 60 (B95) 22.87 4.00 4.29 (B91) 2.79

Test Conditions: Taber Met-Abrader machine, 12.7 mm (0.5 in.) crossed (90°) cylinders, dry. 71 N load (16 lbs), 105 RPM, room temperature. 120 gm surface finish, 10 000 cycles degreased, duplicates weight loss corrected for density differences.

CAVITATION RESISTANCE OF ANNEALED NITRONIC 50 STAINLESS STEEL
Alloy Weight Loss, mg
NITRONIC 50 30
Type 316 100

Data provided by outside laboratory per ASTM G32 Test Method.

Corrosion Resistance

LABORATORY CORROSION TEST DATA
Test Medium Corrosion Rates(1)
NITRONIC 50 Bar Annealed 1066 °C (1950 °F), g/mm2 (g/in.2) NITRONIC 50 Bar Annealed 1121 °C (2050 °F), g/mm2 (g/in.2) NITRONIC 50 HighStrength (HS) Bar (3), g/mm2 (g/in.2)
10% FeCl3, 25C-Plain(2) 0.6 (< 0.001) 0.6 (< 0.001) 0.6 (< 0.001)
10% FeCl3, 25C-creviced(2) 0.6 (< 0.001) 0.6 (< 0.001) 0.6 (< 0.001)
mm/y (MPY(4)) mm/y (MPY(4)) mm/y (MPY(4))
1% H2 SO4, 80 °C < 0.03 (< 1) < 0.03 (< 1) < 0.03 (< 1)
2% H2 SO4, 80 °C < 0.03 (< 1) < 0.03 (< 1) < 0.03 (< 1)
5% H2 SO4, 80 °C < 0.03 (< 1) < 0.03 (< 1) < 0.03 (< 1)
10% H2 SO4, 80 °C 0.71 (28)
20% H2 SO4, 80 °C 3.38 (133)
1% H2 SO4, Boiling 0.69 (27)
2% H2 SO4, Boiling 1.63 (64)
5% H2 SO4, Boiling 4.93 (194) 3.33 (131) 7.52 (296)
10% H2 SO4, Boiling 9.04 (356)
20% H2 SO4, Boiling 41.66 (1640)
1% HCL, 35 °C < 0.03 (< 1) < 0.03 (< 1) < 0.03 (< 1)
2% HCL, 35 °C 0.61 (24) < 0.03 (< 1) 0.69 (27)
1% HCL, 80 °C < 0.03 (< 1) 6.07 (239)
2% HCL, 80 °C 11.15 (439) 11.48 (452)
65% HNO3, Boiling 0.25 (10) 0.18 (7)
70% H3 PO4, Boiling 5.16 (203) 3.91 (154)
33% Acetic Acid, Boiling < 0.03 (< 1) < 0.03 (< 1) < 0.03 (< 1)
20% Formic Acid, Boiling < 0.03 (< 1)
40% Formic Acid, Boiling 0.81 (32)
10% HNO3 + 1% HF, 35 °C 0.18 (7)
10% HNO3 + 1% HF, 80 °C 1.75 (69)

(1)Immersion test performed on 15.9 mm (0.625 in.) diameter x 15.9 mm (0.625 in.) long machined cylinders. Results are average of five 48-hour periods. Specimens tested at 35 and 80 °C were intentionally activated for third, fourth, and fifth periods. Where both active and passive conditions occurred, only active rates are shown.     (2)Exposure for 50 hours with rubber bands on some specimens to produce crevices.     (3)Corrosion rates for hot rolled bars. For other mill products, contact AK Steel International.     (4)Mils Per Year (MPY) = 0.001 in. per year.

LABORATORY CORROSION TEST DATE CAST NITRONIC 50
Test Medium NITRONIC 50 As-Cast, mm/y (MPY)  NITRONIC 50 Cast + Annealed 1121 °C (2050 °F), mm/y (MPY)
10% FeCl3 – Uncreviced 50 hrs, Room Temperature 0.6 g/mm2 (< 0.001 g/in.2)
10% FeCl3 – Crevices 50 hrs, Room Temperature 187 g/mm2 (0.029 g/in.2)
5% H2 SO4 , 80 °C 2.41 (95) 2.06 (81)
5% H2 SO4 , Boiling 10.62 (418)
1% HCL, 35 °C < 0.03 (< 1) < 0.03 (< 1)
70% H3 PO4 Boiling 2.11 (83)

All test performed on 15.9 mm (0.625 in.) diameter x 15.9 mm (0.625 in.) long machined cylinders. Except for the ferric chloride tests, all results are the average of five 48-hour periods. Specimens tested at 35 and at 80 °C were intentionally activated for the third, fourth, and fifth periods. Where both active and passive periods occurred, only active rates are shown.

INTERGRANULAR CORROSION RESISTANCE OF CAST NITRONIC 50
Huey Test   % Ferrite
Annealed*, mm/y (MPY) Sensitized#, mm/y (MPY)
0.15 (6) 0.18 (7.20) Nil
0.12 (4.8) 0.46 (18.0) 4

*1121 °C (2050 °F) – 30 Minute-Water Quenched      #1121 °C (2050 °F) – 30 Minute-Water Quenched + 677 °C (1250 °F) – 30 Minute – Air Cooled. Even sensitized cast NITRONIC 50 Stainless Steel has an acceptable intergranular corrosion rate less than 0.61 mm/y (24 MPY) with up to 4% ferrite present.

INTERGRANULAR ATTACK RESISTANCE OF ARMCO NITRONIC 50 BAR PER ASTM A262

Condition Practice B Ferric Sulfate, mm/y (MPY) Practice E Copper-Copper Sulfate
Annealed 1066 °C (1950 °F) 0.30 (12.0) Passed
Annealed 1066 °C (1950 °F) + 677 °C (1250 °F) – 1 hr – A.C. 1.16 (45.6) Passed
Annealed 1121 °C (2050 °F) 0.27 (10.8) Passed
Annealed 1121 °C (2050 °F) + 677 °C (1250 °F) – 1 hr – A.C. 0.67 (26.4) Passed
High-Strength (Bar Mill) 0.94 (37.2) Passed
High-Strength (Precision Rotary Forging, PRF): Edge 0.40 (15.6) Passed
High-Strength (Precision Rotary Forging, PRF): Intermediate 0.37 (14.4) Passed
High-Strength (Precision Rotary Forging, PRF): Center 0.34 (13.2) Passed

 

BOILING MgCl2
Alloy  Condition Time to Failure, Hours Under Stress of
517 MPa (75 ksi)  345 MPa (50 ksi) 172 MPa (25 ksi)
Type 304 Annealed 0.2 0.3 0.8
Type 316 Annealed 0.8 2.5 7.0
NITRONIC 50 Annealed 0.4 1.2 5.0
NITRONIC 50 High-Strength 1.2 1.5 6.0
NITRONIC 50 Cold Drawn 1.2 2.6 3.3

 

RESISTANCE TO SULFIDE STRESS CRACKING(1)
Alloy Condition Rockwell Hardness, C 0.2% YS, MPa (ksi) Time to Failure, hr, Under Stress, MPa (ksi)
1034 (150) 965 (140) 862 (125) 690 (100) 517 (75) 345 (50) 172 (25)
NITRONIC 50 Annealed 1066 °C (1950 °F) 22 488 (67) > 1000 > 1000 > 1000
High-Strength (HS)(3) 25.4 mm (1 in.) dia. 33 931 (135) 204 320 > 1000 > 1000
High-Strength (HS)(3) 25.4 mm (1 in.) dia. 35 1007 (146) 358
High-Strength (HS)(3) 25.4 mm (1 in.) dia. 36 993 (144) 170(2)  > 1000 > 1000 > 1000
Cold Drawn 9.5 mm (0.375 in.) dia. 41 993 (144) > 1000 > 1000
17-4 PH H 1150D 32.5 758 (110) est 9.5 16 225
H 1150M 29 586 (85) 13.5 29 850

(1)Longitudinal tensile specimens tested according to NACE TM0177.   (2)Ductile creep failure.   (3)For hot rolled bars only.

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