HAYNES® 188 alloy
Principal Features
Excellent High-Temperature Strength and Environment Resistance
HAYNES® 188 alloy (UNS R30188) is a cobalt-nickel-chromium-tungsten alloy that combines excellent high-temperature strength with very good resistance to oxidizing environments up to 2000°F (1095°C) for prolonged exposures, and excellent resistance to sulfate deposit hot corrosion. It is readily fabricated and formed by conventional techniques, and has been used for cast component. Other attractive features include excellent resistance to molten chloride salts, and good resistance to gaseous sulfidation.
Readily Fabricated
HAYNES® 188 alloy has good forming and welding characteristics. It may be forged or other hot-worked, providing that it is held at 2150°F (1175°C) for a time sufficient to bring the entire piece to temperature. As a consequence of its good ductility, 188 alloy is also readily formed by cold working. The alloy does work-harden rapidly, however, so frequent intermediate annealing treatments may be needed for complex component forming operations. All hot- or cold- worked parts should be annealed and rapidly cooled in order to restore the best balance of properties.
The alloy can be welded by both manual and automatic welding methods, including gas tungsten arc (TIG), gas metal arc (MIG), electron beam and resistance welding. It exhibits good restraint welding characteristics.
Heat Treatment
Wrought HAYNES® 188 alloy is furnished in the solution heat treated condition, unless otherwise specified. The alloy is normally solution heat-treated at 2125-2175°F (1163-1191°C) and rapidly cooled or water quenched for optimal properties.
Annealing at temperatures less than the solution heat-treating temperature will produce some carbide precipitation in alloy 188, which may affect the alloy’s properties.
Applications
HAYNES® 188 alloy combines properties which make is suitable for a variety of fabricated component applications in the aerospace industry. It is widely used in established military and commercial gas turbine engines for combustion cans, transitions ducts, and afterburner components. It shares applications in newer engine programs with a more recently developed material, 230® alloy, which possesses improved properties.
*Please contact our technical support team if you have technical questions about this alloy.
Nominal Composition
| Weight % | |
| Cobalt | 39 Balance |
| Nickel | 22 |
| Chromium | 22 |
| Tungsten | 14 |
| Iron | 3 max. |
| Manganese | 1.25 max. |
| Silicon | 0.35 |
| Carbon | 0.10 |
| Lanthanum | 0.03 |
| Boron | 0.015 max. |
Creep and Stress-Rupture Strength
HAYNES 188 alloy is a solid-solution- strengthened material which combines excellent high-temperature strength with good fabricability at room temperature. It is particularly effective for very long-term applications at temperatures of 1200°F (650°C) or more. It is stronger than nickel-base solid-solution-strengthened alloys, and far stronger than simple nickel chromium or iron-nickel-chromium heat-resistant alloys. This can allow for significant section thickness reduction when it is substituted for these materials.
Comparision of Sheet Materials: Stress to Produce 1% Creep in 1000 Hours
188 Plate, Solution-Annealed
| Temperature | Creep | Approximate Initial Stress to Produce Specified Creep in | ||||||||
| 10 h | 100 h | 1,000 h | 10,000 h | |||||||
| °F | °C | % | ksi | MPa | ksi | MPa | ksi | MPa | ksi | MPa |
| 1200 | 649 | 0.5 | — | — | — | — | — | — | — | — |
| 1 | — | — | — | — | 35* | 241* | — | — | ||
| R | — | — | 78 | 538 | 59 | 407 | 45* | 310* | ||
| 1300 | 704 | 0.5 | 41 | 283 | 28 | 193 | 18* | 124* | — | — |
| 1 | 44 | 303 | 31.5 | 217 | 22 | 152 | — | — | ||
| R | 73* | 503* | 54 | 372 | 40 | 276 | 28 | 193 | ||
| 1400 | 760 | 0.5 | 26 | 179 | 17 | 117 | 11.5 | 79 | — | — |
| 1 | 29 | 200 | 20.5 | 141 | 14.5* | 100* | — | — | ||
| R | 51 | 352 | 37 | 255 | 26 | 179 | 18.5* | 128* | ||
| 1500 | 816 | 0.5 | 16 | 110 | 11.0 | 76 | 7.7* | 53* | — | — |
| 1 | 19 | 131 | 13.5 | 93 | 9.3 | 64 | — | — | ||
| R | 36 | 248 | 25 | 172 | 17.5 | 121 | 12.0 | 83 | ||
| 1600 | 871 | 0.5 | 11.5 | 79 | 7.5 | 52 | 5.5* | 38* | — | — |
| 1 | 13.0 | 90 | 9.0 | 62 | 6.4* | 44* | — | — | ||
| R | 25 | 172 | 17.0 | 117 | 11.6 | 80 | 7.8 | 54 | ||
| 1700 | 927 | 0.5 | 8.0 | 55 | 5.2 | 36 | 3.6* | 25* | — | — |
| 1 | 9.2 | 63 | 6.0 | 41 | 4.3* | 30* | — | — | ||
| R | 16.5 | 114 | 11.1 | 77 | 7.3 | 50 | 4.5* | 31* | ||
| 1800 | 982 | 0.5 | 5.6 | 39 | 3.6 | 25 | 2.3 | 16 | 1.35 | 9.3 |
| 1 | 6.3 | 43 | 4.2 | 29 | 2.5 | 17 | 1.42 | 9.8 | ||
| R | 11.5 | 79 | 7.0 | 48 | 4.0 | 28 | 2.2* | 15* | ||
| 1900 | 1038 | 0.5 | 3.7 | 26 | 2.3* | 16* | — | — | — | — |
| 1 | 4.2 | 29 | 2.5* | 17* | — | — | — | — | ||
| R | 7.2* | 50* | 4.4 | 30 | 2.2* | 15* | — | — | ||
| 2000 | 1093 | 0.5 | 2.3 | 16 | 1.35 | 9.3 | — | — | — | — |
| 1 | 2.6 | 18 | 1.42 | 9.8 | — | — | — | — | ||
| R | 4.7 | 32 | 2.3 | 16 | 1.10* | 7.6* | — | — | ||
*Significant extrapolation
188 Sheet, Solution-Annealed
| Temperature | Creep | Approximate Initial Stress to Produce Specified Creep in | ||||||
| 10 h | 100 h | 1,000 h | ||||||
| °F | °C | % | ksi | MPa | ksi | MPa | ksi | MPa |
| 1400 | 760 | 0.5 | 22.5 | 155 | 16.4 | 113 | 11.7 | 81 |
| 1 | 25.5 | 176 | 18.5 | 128 | 13.3 | 92 | ||
| R | 43.0* | 296* | 32.0 | 221 | 23.0 | 159 | ||
| 1500 | 816 | 0.5 | 15.5 | 107 | 11.1 | 77 | 7.8 | 54 |
| 1 | 17.6 | 121 | 12.6 | 87 | 8.8 | 61 | ||
| R | 31.0 | 214 | 21.7 | 150 | 15.0 | 103 | ||
| 1600 | 871 | 0.5 | 10.7 | 74 | 7.5 | 52 | 5.0 | 34 |
| 1 | 12.2 | 84 | 8.4 | 58 | 5.7 | 39 | ||
| R | 21.0 | 145 | 14.4 | 99 | 9.4 | 65 | ||
| 1700 | 927 | 0.5 | 7.3 | 50 | 4.9 | 34 | 3.1 | 21 |
| 1 | 8.2 | 57 | 5.6 | 39 | 3.6 | 25 | ||
| R | 14.3 | 99 | 9.1 | 63 | 5.5* | 38* | ||
| 1800 | 982 | 0.5 | 4.9 | 34 | 3.1 | 21 | 1.8 | 12 |
| 1 | 5.6 | 39 | 3.6 | 25 | 2.1 | 14 | ||
| R | 9.1 | 63 | 5.4 | 37 | 3.0 | 21 | ||
| 1900 | 1038 | 0.5 | 3.1 | 21 | 1.9 | 13 | 1.2 | 8.3 |
| 1 | 3.6 | 25 | 2.2 | 15 | 1.4 | 9.7 | ||
| R | 5.5 | 38 | 3.2 | 22 | 2.0 | 14 | ||
| 2000 | 1093 | 0.5 | 2.0* | 14* | 1.2 | 8.3 | 0.70 | 4.8 |
| 1 | 2.3* | 16* | 1.4 | 9.7 | 0.90 | 6.2 | ||
| R | 3.3* | 23* | 2.0 | 14 | 1.2 | 8.3 | ||
*Significant extrapolation
Tensile Properties
Hot-Rolled and Solution-annealed Plate
| Test Temperature | 0.2% Yield Strength | Ultimate Tensile Strength | Elongation | |||
| °F | °C | ksi | MPa | ksi | MPa | % |
| RT | RT | 70.1 | 483 | 143.8 | 991 | 50.6 |
| 1000 | 538 | 45.7 | 315 | 120.6 | 832 | 60.3 |
| 1200 | 649 | 45.1 | 311 | 121.6 | 838 | 62.8 |
| 1400 | 760 | 43.6 | 301 | 84.1 | 580 | 85.6 |
| 1600 | 871 | 37.1 | 256 | 49.5 | 341 | 97.9 |
| 1800 | 982 | 19.2 | 132 | 27.2 | 188 | 102.6 |
| 2000 | 1093 | 9.6 | 66 | 13.9 | 96 | 87.1 |
Cold-Rolled and Solution-annealed Sheet
| Test Temperature | 0.2% Yield Strength | Ultimate Tensile Strength | Elongation | |||
| °F | °C | ksi | MPa | ksi | MPa | % |
| RT | RT | 70.1 | 483 | 142.4 | 982 | 50.9 |
| 1000 | 538 | 44.8 | 309 | 117.4 | 809 | 58.8 |
| 1200 | 649 | 44.8 | 309 | 119.1 | 821 | 58.6 |
| 1400 | 760 | 43.8 | 302 | 81.6 | 563 | 81.8 |
| 1600 | 871 | 37.8 | 261 | 47.0 | 324 | 103.9 |
| 1800 | 982 | 18.2 | 125 | 25.4 | 175 | 81.0 |
| 2000 | 1093 | 8.5 | 59 | 12.4 | 85 | 49.7 |
Hardness Data
Solution Annealed Room Temperature Hardness
| Form | Hardness, HRBW | Typical ASTM Grain Size |
| Sheet | 98 | 5 – 7.5 |
| Plate | 98 | 4 – 8 |
| Bar | 96 | 3.5 – 7.5 |
All samples tested in solution-annealed condition
HRBW = Hardness Rockwell “B”, Tungsten Indentor.
High-Temperature Hardness
| Temperature | 188 | 25 | 6B | 230® | 556® | ||||||
| Vickers Hardness | Rockwell Hardness | Vickers Hardness | Rockwell Hardness | Vickers Hardness | Rockwell Hardness | Vickers Hardness | Rockwell Hardness | Vickers Hardness | Rockwell Hardness | ||
| °F | °C | DPN | HR C/BW | DPN | HR C/BW | DPN | HR C/BW | DPN | HR C/B | DPN | HR C/BW |
| 72 | RT | 248 | 21.8 C | 285 | 27.8 C | 374 | 38.2 C | 195 | 92.0 BW | 203 | 93.6 BW |
| 800 | 427 | 170 | 86.3 BW | 171 | 86.7 BW | 269 | 25.5 C | 142 | 77.3 BW | 132 | 73.0 BW |
| 1000 | 538 | 159 | 83.0 BW | 160 | 73.3 BW | 247 | 21.8 C | 139 | 76.0 BW | 129 | 71.1 BW |
| 1200 | 649 | 147 | 77.2 BW | 150 | 80.0 BW | 225 | 97.5 BW | 132 | 73.0 BW | 118 | 66.5 BW |
| 1400 | 760 | 129 | 70.7 BW | 134 | 73.7 BW | 153 | 81.0 BW | 125 | 70.0 BW | 100 | 55.0 BW |
| 1600 | 871 | 89 | – | 93 | – | 91 | – | 75 | – | 67 | – |
| 1800 | 982 | 49 | – | 52 | – | 55 | – | 42 | – | 41* | – |
HRC = Hardness Rockwell “C”.
HRBW = Hardness Rockwell “B”, Tungsten Indentor.
Impact Strength Properties
| Test Temperature | Typical Charpy V-Notch Impact Resistance | ||
| °F | °C | ft.-lbs | J |
| -300 | -185 | 116 | 158 |
| -150 | -100 | 131 | 178 |
| 70 | 20 | 143 | 194 |
| 1000 | 540 | 117 | 159 |
| 1300 | 705 | 107 | 145 |
*Average of longitudinal and transverse tests on solution-annealed plate
Thermal Stability
HAYNES® 188 alloy is similar to the solid-solution-strengthened superalloys, such as alloy 625 or HASTELLOY® X alloy, which will precipitate deleterious phases upon such long-term exposure. In this case. the phase in question is a CO2W laves phase. which serves to impair both tensile ductility and impact strength. The behavior of 188 alloy is significantly better in this regard than HAYNES® 25 alloy, which it replaced; but for applications where thermal stability is important, 230® alloy is recommended.
Room-Temperature Properties of Plate after Thermal Exposure
| Exposure Temperature | – | 0.2% Yield Strength | Ultimate Tensile Strength | Elongation | Impact Strength | ||||
| °F | °C | h | ksi | MPa | ksi | MPa | % | ft.- lbs. | J |
| 1200 | 650 | 0 | 65.0 | 450 | 140.0 | 965 | 56.0 | 143 | 194 |
| 8000 | 79.7 | 550 | 151.6 | 1045 | 29.1 | 23 | 31 | ||
| 1400 | 760 | 0 | 65.0 | 450 | 140.0 | 965 | 56.0 | 143 | 194 |
| 8000 | 74.0 | 510 | 147.9 | 1020 | 10.8 | 3 | 4 | ||
| 1600 | 870 | 0* | 70.1 | 485 | 146.0 | 1005 | 50.4 | 143 | 194 |
| 1000 | 70.7 | 490 | 157.5 | 1085 | 28.7 | 10 | 13 | ||
| 4000 | 68.8 | 475 | 156.0 | 1075 | 26.6 | 10 | 13 | ||
| 8000* | 64.5 | 445 | 147.4 | 1015 | 22.2 | 9 | 12 | ||
| 16000 | 63.8 | 440 | 146.1 | 1005 | 24.0 | 8 | 11 | ||
*Average of two test exposure. All other single exposures.
Comparative Impact Strength after 8000-Hour Exposures
| Alloy | Solution-Annealed Charpy V-Notch Impact | Charpy V-Notch Impact Following Exposure For 8000 Hours at Temperatures | ||||||
| 1200°F | 650°C | 1400°F | 760°C | 1600°F | 870°C | |||
| – | ft.-lbs. | J | ft.-lbs | J | ft.-lbs | J | ft.-lbs | J |
| 230® | 54 | 73 | 30 | 41 | 21 | 28 | 21 | 28 |
| 188 | 143 | 194 | 23 | 31 | 3 | 4 | 9 | 12 |
| X | 54 | 73 | 15 | 20 | 8 | 11 | 15 | 20 |
| 625 | 81 | 110 | 5 | 7 | 5 | 7 | 15 | 20 |
Physical Properties
| Physical Property | British Units | Metric Units | ||
| Density | RT |
0.324 lb/in3 |
RT |
8.98 g/cm3 |
| Melting Temperature | 2400-2570°F | - | 1315-1410°C | - |
| Electrical Resistivity | RT | 39.6 µohm-in | RT | 101.0 µohm-cm |
| 200°F | 40.3 µohm-in | 100°C | 103.0 µohm-cm | |
| 400°F | 41.5 µohm-in | 200°C | 105.0 µohm-cm | |
| 600°F | 42.7 µohm-in | 300°C | 107.7 µohm-cm | |
| 800°F | 43.8 µohm-in | 400°C | 110.5 µohm-cm | |
| 1000°F | 44.7 µohm-in | 500°C | 112.7 µohm-cm | |
| 1200°F | 45.6 µohm-in | 600°C | 114.8 µohm-cm | |
| 1400°F | 46.1 µohm-in | 700°C | 116.4 µohm-cm | |
| 1600°F | 46.5 µohm-in | 800°C | 117.5 µohm-cm | |
| 1800°F | 46.7 µohm-in | 900°C | 118.3 µohm-cm | |
| 2000°F | 46.8 µohm-in | 1000°C | 119.1 µohm-cm | |
| Specific Heat | RT | 0.096 Btu/lb-°F | RT | 12.1 J/kg·°C |
| 200°F | 0.101 Btu/lb-°F | 100°C | 423 J/kg·°C | |
| 400°F | 0.106 Btu/lb-°F | 200°C | 444 J/kg·°C | |
| 600°F | 0.112 Btu/lb-°F | 300°C | 465 J/kg·°C | |
| 800°F | 0.117 Btu/lb-°F | 400°C | 486 J/kg·°C | |
| 1000°F | 0.122 Btu/lb-°F | 500°C | 502 J/kg·°C | |
| 1200°F | 0.127 Btu/lb-°F | 600°C | 523 J/kg·°C | |
| 1400°F | 0.131 Btu/lb-°F | 700°C | 540 J/kg·°C | |
| 1600°F | 0.136 Btu/lb-°F | 800°C | 557 J/kg·°C | |
| 1800°F | 0.140 Btu/lb-°F | 900°C | 573 J/kg·°C | |
| 2000° F | 0.145 Btu/lb-°F | 1000°C | 590 J/kg·°C | |
| Thermal Conductivity | RT |
72 Btu-in/ft2-hr-°F |
RT | 10.4 W/m-°C |
| 200°F |
84 Btu-in/ft2-hr-°F |
100°C | 12.2 W/m-°C | |
| 400°F |
100 Btu-in/ft2-hr-°F |
200°C | 14.3 W/m-°C | |
| 600°F |
112 Btu-in/ft2-hr-°F |
300°C | 15.9 W/m-°C | |
| 800°F |
125 Btu-in/ft2-hr-°F |
400°C | 17.5 W/m-°C | |
| 1000°F |
138 Btu-in/ft2-hr-°F |
500°C | 19.3 W/m-°C | |
| 1200°F |
152 Btu-in/ft2-hr-°F |
600°C | 21.1 W/m-°C | |
| 1400°F |
167 Btu-in/ft2-hr-°F |
700°C | 23.0 W/m-°C | |
| 1600°F |
174 Btu-in/ft2-hr-°F |
800°C | 24.8 W/m-°C | |
| 1800°F |
189 Btu-in/ft2-hr-°F |
900°C | 25.5 W/m-°C | |
| 2000°F |
204 Btu-in/ft2-hr-°F |
1000°C | 27.6 W/m-°C | |
| Thermal Diffusivity | RT |
4.5 x 10-3 in2/sec |
RT |
29.2 x 10-3 cm2/sec |
| 200°F |
5.0 x 10-3 in2/sec |
100°C |
32.7 x 10-3 cm2/sec |
|
| 400°F |
5.6 x 10-3 in2/sec |
200°C |
36.5 x 10-3 cm2/sec |
|
| 600°F |
6.0 x 10-3 in2/sec |
300°C |
38.7 x 10-3 cm2/sec |
|
| 800°F |
6.4 x 10-3 in2/sec |
400°C |
40.8 x 10-3 cm2/sec |
|
| 1000°F |
6.7 x 10-3
in2/sec |
500°C |
43.5 x 10-3 cm2/sec |
|
| 1200°F |
7.1 x 10-3 in2/sec |
600°C |
45.7 x 10-3 cm2/sec |
|
| 1400°F |
7.6 x 10-3 in2/sec |
700°C |
48.2 x 10-3 cm2/sec |
|
| 1600°F |
7.6 x 10-3 in2/sec |
800°C |
50.4 x 10-3 cm2/sec |
|
| 1800°F |
8.0 x 10-3 in2/sec |
900°C |
50.4 x 10-3 cm2/sec |
|
| 2000°F |
8.4 x 10-3 in2/sec |
1000°C |
53.0 x 10-3 cm2/sec |
|
| Mean Coefficient of Thermal Expansion | 75 - 200°F |
6.7 10-6 in/in/°F |
25 - 100°C |
12.1 10-6 m/m/°C |
| 75 - 400°F |
7.1 10-6 in/in/°F |
25 - 200°C |
12.7 10-6 m/m/°C |
|
| 75 - 600°F |
7.3 10-6 in/in/°F |
25 - 300°C |
13.1 10-6 m/m/°C |
|
| 75 - 800°F |
7.3 10-6 in/in/°F |
25 - 400°C |
13.5 10-6 m/m/°C |
|
| 75 - 1000°F |
7.7 10-6 in/in/°F |
25 - 500°C |
13.9 10-6 m/m/°C |
|
| 75 - 1200°F |
8.2 10-6 in/in/°F |
25 - 600°C |
14.3 10-6 m/m/°C |
|
| 75 - 1400°F |
8.5 10-6 in/in/°F |
25 - 700°C |
15.0 10-6 m/m/°C |
|
| 75 - 1600°F |
8.8 10-6 in/in/°F |
25 - 800°C |
15.5 10-6 m/m/°C |
|
| 75 - 1800°F |
9.1 10-6 in/in/°F |
25 - 900°C |
16.0 10-6 m/m/°C |
|
| - | - | 25 - 1000°C |
16.5 10-6 m/m/°C |
|
| Dynamic Modulus of Elasticity | RT |
33.7 x 106 psi |
RT | 232 GPa |
| 200°F |
32.9 x 106 psi |
100°C | 226 GPa | |
| 400°F |
31.8 x 106 psi |
200°C | 220 GPa | |
| 600°F |
30.8 x 106 psi |
300°C | 213 GPa | |
| 800°F |
29.5 x 106 psi |
400°C | 206 GPa | |
| 1000°F |
28.6 x 106 psi |
500°C | 198 GPa | |
| 1200°F |
27.1 x 106 psi |
600°C | 189 GPa | |
| 1400°F |
25.6 x 106 psi |
700°C | 180 GPa | |
| 1600°F |
24.0 x 106 psi |
800°C | 171 GPa | |
| 1800°F |
22.2 x 106 psi |
900°C | 160 GPa | |
| 2000°F |
20.2 x 106 psi |
1000°C | 150 GPa | |
| Dynamic Shear Modulus | RT |
13.0 x 106 psi |
RT | 90 GPa |
| 400°F |
12.5 x 106 psi |
100°C | 88 GPa | |
| 600°F |
12.0 x 106 psi |
200°C | 86 GPa | |
| 800°F |
11.4 x 106 psi |
300°C | 83 GPa | |
| 1000°F |
10.9 x 106 psi |
400°C | 80 GPa | |
| 1200°F |
10.3 x 106 psi |
500°C | 76 GPa | |
| 1400°F |
9.7 x 106 psi |
600°C | 73 GPa | |
| 1600°F |
9.0 x 106 psi |
700°C | 69 GPa | |
| 1800ºF |
8.3 x 106 psi |
800ºC | 65 GPa | |
| 2000°F |
7.5 x 106 psi |
900°C | 61 GPa | |
| - | - | 1000ºC | 56 GPa | |
| Poisson's Ratio | RT°F | 0.3 | RT | 0.30 |
| 200°F | 0.29 | 100°C | 0.29 | |
| 400°F | 0.27 | 200°C | 0.27 | |
| 600°F | 0.29 | 300°C | 0.29 | |
| 800°F | 0.29 | 400°C | 0.29 | |
| 1000°F | 0.31 | 500°C | 0.30 | |
| 1200°F | 0.32 | 600°C | 0.31 | |
| 1400°F | 0.32 | 700°C | 0.32 | |
| 1600°F | 0.33 | 800°C | 0.32 | |
| 1800°F | 0.33 | 900°C | 0.33 | |
| 2000°F | 0.34 | 1000°C | 0.33 | |
RT = Room Temperature
Low Cycle Fatigue Properties
HAYNES® 188 alloy exhibits very good low cycle fatigue properties at elevated temperatures. Results shown below are for strain-controlled tests run in the temperature range from 800°F (425°C) to 1600°F (870°C). Samples were machined from bar. Tests were run with fully reversed strain (R = -1) at a frequency of 20 cpm (0.33 Hz).
Comparative Low Cycle Fatigue Properties.
The graph below compares the low cycle fatigue lives of a number of alloys tested at 800°F (425°C) in both the as-received and 1400°F (760°C)/1000 hour pre-exposed condition. Samples were machined from plate or bar, after exposure for exposed samples. Tests were again run with fully reversed strain (R = -1) at a frequency of 20 cpm (0.33 Hz). TSR = Total Strain Range.
Oxidation Resistance
HAYNES® 188 alloy exhibits very good resistance to both air and combustion gas oxidizing environments, and can be used for long-term continuous exposure at temperatures up to 2000°F (1095°C). For exposures of short duration, 188 alloy can be used at higher temperatures.
Comparative Oxidation Resistance in Flowing Air, 1008 Hours
| Alloy | 1800°F (980°C) | 2000°F (1095°C) | 2100°F (1150°C) | |||||||||
| Average Metal Affected** | Metal Loss | Average Metal Affected** | Metal Loss | Average Metal Affected** | Metal Loss | |||||||
| mils | μm | mils | μm | mils | μm | mils | μm | mils | μm | mils | μm | |
| 188 | 1.1 | 28 | 0.1 | 3 | 3.7 | 94 | 0.5 | 13 | 10.7 | 272 | 8.6 | 218 |
| 230® | 1.5 | 38 | 0.2 | 5 | 3.3 | 84 | 0.5 | 13 | 4.4 | 112 | 1.2 | 30 |
| X | 1.5 | 38 | 0.2 | 5 | 4.4 | 112 | 1.3 | 33 | 6.1 | 115 | 3.6 | 91 |
| 625 | 1.9 | 48 | 0.4 | 10 | 7.8 | 198 | 3.5 | 89 | 20.2 | 513 | 18.3 | 465 |
| 617 | 2.0 | 51 | 0.3 | 8 | 3.8 | 97 | 0.6 | 15 | 5.2 | 132 | 1.0 | 25 |
*Flowing air at a velocity of 7.0 ft/min (213.4 cm/min) past the samples. Samples cycled to room temperature once per week.
**Metal Loss + Average Internal Penetration
Oxidation Test Parameters
Burner rig oxidation tests were conducted by exposing sampIes 3/8 in. x 2.5 in. x thickness (9 mm x 64 mm x thickness), in a rotating holder, to products of combustion of No. 2 fuel oil burned at a ratio of air to fuel of about 50:1. (Gas velocity was about 0.3 mach). Samples were automatically removed from the gas stream every 30 minutes and fan-cooled to near ambient temperature and then reinserted into the flame tunnel.
Comparative Burner Rig Oxidation Resistance 1000 Hour Exposure at 1800°F (980°C)
| 1000 Hour Exposure at 1800°F (980°C), 30 Minute Cycles | ||||||
| Alloy | Metal Loss | Average Metal Affected | Maximum Metal Affected | |||
| mils | μm | mils | μm | mils | μm | |
| 188 | 1.1 | 28 | 3.2 | 81 | 3.9 | 99 |
| 230® | 2.8 | 71 | 5.6 | 142 | 6.4 | 163 |
| 617 | 2.4 | 61 | 5.7 | 145 | 6.9 | 175 |
| 625 | 3.7 | 94 | 6.0 | 152 | 6.6 | 168 |
| X | 4.3 | 109 | 7.3 | 185 | 8.0 | 203 |
Comparative Burner Rig Oxidation Resistance at 2000ºF (1095ºC) for 500 Hours
| 500 Hour Exposure at 2000°F (1095°C), 30 Minute Cycles | ||||||
| Alloy | Average Metal Loss Per Side | Average Metal Affected | Maximum Metal Affected | |||
| mils | μm | mils | μm | mils | μm | |
| 230® | 7.1 | 180 | 9.9 | 251 | 11.8 | 300 |
| 188 | 10.9 | 277 | 13.1 | 333 | 14.1 | 358 |
| X | 11.6 | 295 | 14.0 | 356 | 15.1 | 384 |
| 617 | 13.3 | 338 | 20.9 | 531 | 21.2 | 538 |
| 625 | Consumed | |||||
*625 was consumed
Water Vapor Oxidation Data
|
Air + 20% H2O at 1800°F (982°C), 1008 hours, cycled weekly |
||||
| Alloy | Metal Loss | Average Metal Affected | ||
| mils | μm | mils | μm | |
| 214® | 0.04 | 1 | 0.64 | 16 |
| 230® | 0.19 | 5 | 1.59 | 40 |
| 625 | 0.36 | 9 | 1.66 | 42 |
| 188 | 0.18 | 5 | 1.48 | 38 |
| X | 0.27 | 7 | 1.77 | 45 |
| 617 | 0.39 | 10 | 1.99 | 50 |
| 556® | 0.35 | 9 | 1.85 | 47 |
| HR‐120® | 0.38 | 10 | 2.08 | 53 |
| 800HT | 2.47 | 63 | 5.07 | 129 |
| HR‐160® | 0.77 | 20 | 5.57 | 141 |
Hot Corrosion Resistance
HAYNES® 188 alloy exhibits excellent resistance to sulfate deposit type hot corrosion. Tests were conducted in a low velocity burner rig burning No. 2 Fuel oil with 0.4 percent sulfur. The air:fuel ratio was 30:1. Artificial sea water was injected at a rate equivalent to 5 ppm salt. Tests were run for 1000 hours, with samples cycled out of the gas stream once an hour and cooled to near ambient temperature. Gas velocity was 13 ft./ sec. (4 m/s).
Hot Corrosion Resistance at 1650°F (900°C)
| Alloy | Metal Loss | Average Metal Affected | ||
|---|---|---|---|---|
| – | mils | µm | mils | µm |
| 188 | 0.8 | 20 | 2.7 | 69 |
| 230® | 1.2 | 30 | 5.1 | 130 |
| 625 | 1.8 | 46 | 5.2 | 132 |
| X | 1.6 | 41 | 5.5 | 140 |
Schematic Representation of Metallographic Technique
Used for Evaluating Environmental Tests
Sulfidation Resistance
HAYNES® 188 alloy has very good resistance to gaseous sulfidation envronments encountered in various industrial applications. Tests were conducted at 1400°F (760°C) in a gas mixture consisting of 5 percent H2, 5 percent CO1, 1 percent CO2 , and 0.15 percent H2S, balance Ar. Coupons were exposed for 215 hours. This is a severe test, with equilibrium sulfur partial pressure of 10-6 to 10-7 and oxygen partial pressures less than that needed to produce protective chromium oxide scales.
Sulfidation Resistance at 1400°F (760°C)
|
215 hours in an atmosphere of 5% H2 + 5% CO + 0.15% H2S + Balance Ar |
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| Alloy | 1400°F (760°C) | 1600°F (871°C) | ||||||
| Metal Loss | Average Metal Affected | Metal Loss | Average Metal Affected | |||||
| mils | μm | mils | μm | mils | μm | mils | μm | |
| 25 | 0.5 | 13 | 1.5 | 38 | 1.1 | 28 | 5.3 | 135 |
| 188 | 1.6 | 41 | 3.3 | 84 | 1.7 | 44 | 5.7 | 145 |
| 556® | 3.1 | 77 | 4.9 | 124 | 6.2 | 157 | 16.4 | 417 |
| 310 | 6.2 | 157 | 9.1 | 231 | 8.3 | 211 | 14.1 | 358 |
| 617 | 5.0 | 127 | 10.8 | 274 | 3.8 | 97 | 17.2 | 437 |
| 800H | 7.1 | 180 | 11.2 | 284 | 7.9 | 201 | >27.6 | >701 |
| 625 | 6.6 | 168 | 12.6 | 320 | Partially Consumed | |||
| X | – | – | >29.5 | >749 | – | – | >21.7 | >551 |
Schematic Representation of Metallographic Technique
Used for Evaluating Environmental Tests
Fabrication Characteristics
Heat Treatment
HAYNES® 188 alloy is normally solution heat treated in the range of 2125-2175°F for a time to commensurate with section thickness. Annealing during fabrication can be performed at even lower temperatures, but a final, subsequent solution heat treatment is needed to produce optimum properties and structure.
Effect of Cold Reduction Upon Room-Temperature Properties*
| Cold Reduction | Subsequent Temperature | 0.2% Yield Strength | Ultimate Tensile Strength | Elongation | Hardness | ||
| % | – | ksi | MPa | ksi | MPa | % | HR BW/C |
| 0 | NONE | 66.9 | 460 | 137.2 | 945 | 54.2 | 98.1 HRBW |
| 10 | 105.9 | 730 | 151.5 | 1045 | 45.1 | 32.1 HRC | |
| 20 | 132.9 | 915 | 165.9 | 1145 | 28.3 | 37.1 HRC | |
| 30 | 167.0 | 1150 | 195.1 | 1345 | 13.4 | 41.2 HRC | |
| 40 | 176.8 | 1220 | 214.9 | 1480 | 9.8 | 43.5 HRC | |
| 10 | 1950°F (1065°C) for 5 min. | 91.2 | 630 | 148.5 | 1025 | 41.4 | 29.7 HRC |
| 20 | 87.8 | 605 | 153.3 | 1055 | 41.0 | 27.8 HRC | |
| 30 | 84.2 | 580 | 158.3 | 1090 | 41.3 | 29.6 HRC | |
| 40 | 90.8 | 625 | 162.7 | 1120 | 39.8 | 31.1 HRC | |
| 10 | 2050°F (1120°C) | 64.7 | 445 | 143.0 | 985 | 50.1 | 21.9 HRC |
| 20 | 71.4 | 490 | 149.0 | 1025 | 47.2 | 24.5 HRC | |
| 30 | 80.3 | 555 | 155.2 | 1070 | 43.7 | 27.6 HRC | |
| 40 | 86.9 | 600 | 159.0 | 1095 | 43.2 | 29.5 HRC | |
| 10 | 2150°F (1175°C) for 5 min. | 61.9 | 425 | 139.6 | 965 | 55.3 | 95.6 HRBW |
| 20 | 64.9 | 445 | 141.3 | 975 | 53.3 | 97.1 HRBW | |
| 30 | 66.5 | 460 | 142.8 | 985 | 51.8 | 98.5 HRBW | |
| 40 | 64.1 | 440 | 141.5 | 975 | 55.5 | 97.2 HRBW | |
*Based upon rolling reduction taken upon 0.125 in. (3.2 mm) thick sheet. Duplicate tests.
HRC = Hardness Rockwell “C”.
HRBW= Hardness Rockwell “B”, Tungsten Indentor.
Welding
HAYNES® 188 alloy is readily welded by Gas Tungsten Arc (GTAW), Gas Metal Arc (GMAW), Shielded Metal Arc (SMAW), electron bean welding, and resistance welding techniques. Its welding characteristics are similar to those of HAYNES® 25 alloy. Submerged Arc welding is not recommended, as this process is characterized by high heat input to the base metal and slow cooling of the weld. These factors can increase weld restraint and promote cracking.
Base Metal Preparation
The joint surface and adjacent area should be thoroughly cleaned before welding. All grease, oil, crayon marks, sulfur compounds, and other foreign matter should be removed. Contact with copper or copper-bearing materials in the joint area should be avoided. It is preferable, but not necessary, that the alloy be in the solution-annealed condition when welded.
Filler Metal Selection
Matching composition filler metal is recommended for joining alloy 188. For joining section thicknesses greater than 3/8 inch (9.5 mm), HAYNES® 230-W® filler wire (AWS A5.14 ERNiCrWMo-1) is suggested. For shielded metal arc welding, HAYNES® 25 alloy electrodes (AMS 5797) are suggested. For dissimilar joining of 188 alloy to nickel-, cobalt-, or iron- base materials, 188 alloy itself, 230-W® filler wire, HAYNES® 556® alloy (AMS 5831), HASTELLOY® S alloy (AMS 5838), or HASTELLOY® W alloy (AMS 5786) welding products are suggested, depending upon the particular case. Please click here or see the Haynes Welding SmartGuide for more information.
Preheating, Interpass Temperatures, and Postweld Heat Treatment
Preheat is not required. Preheat is generally specified as room temperature (typical shop conditions). Interpass temperature should be maintained below 200°F (93°C). Auxiliary cooling methods may be used between weld passes, as needed, providing that such methods do not introduce contaminants. Postweld heat treatment is not generally required for 188 alloy. For further information, please click here.
Welded Tensile – Room Temperature
| Condition | 0.2% Yield Strength | Ultimate Tensile Strength | Elongation | ||
| ksi | MPa | ksi | MPa | % | |
| Sheet | 68 | 469 | 133 | 917 | 65 |
| Welded Transverse | 70 | 483 | 123 | 848 | 31 |
| All Weld Metal | 79 | 545 | 117 | 807 | 46 |
Machining
Machining information can be found here.
Specifications and Codes
Specifications
| HAYNES® 188 alloy (R30188) | |
| Sheet, Plate & Strip | AMS 5608 |
| Billet, Rod & Bar | AMS 5772 |
| Coated Electrodes | – |
| Bare Welding Rods & Wire | – |
| Seamless Pipe & Tube | – |
| Welded Pipe & Tube | – |
| Fittings | – |
| Forgings | AMS 5772 |
| DIN | – |
| Others | – |
Codes
| HAYNES® 188 alloy (R30188) | |
| MMPDS | 6.4.2 |
Disclaimer
Haynes International makes all reasonable efforts to ensure the accuracy and correctness of the data displayed on this site but makes no representations or warranties as to the data’s accuracy, correctness or reliability. All data are for general information only and not for providing design advice. Alloy properties disclosed here are based on work conducted principally by Haynes International, Inc. and occasionally supplemented by information from the open literature and, as such, are indicative only of the results of such tests and should not be considered guaranteed maximums or minimums. It is the responsibility of the user to test specific alloys under actual service conditions to determine their suitability for a particular purpose.
For specific concentrations of elements present in a particular product and a discussion of the potential health affects thereof, refer to the Safety Data Sheets supplied by Haynes International, Inc. All trademarks are owned by Haynes International, Inc., unless otherwise indicated.
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