Heat Treatment

Recommended Procedures and Temperatures Applicable to:
Corrosion-resistant Alloys
High-temperature Alloys
Wear & Corrosion-resistant Alloy

The heat treatment of the HAYNES® and HASTELLOY® alloys is a very important topic. In the production of these wrought materials, there are many hot- and cold-reduction steps, between which intermediate heat treatments are necessary, to restore the optimum properties, in particular ductility. In the case of the corrosion-resistant alloys, these intermediate heat treatments are generally solution-annealing treatments. In the case of the high-temperature alloys, this is not necessarily so.

Once the materials have reached their final sizes, they are given a final anneal. This is usually a solution-anneal; however, a few high-temperature alloys (HTA) are final annealed at an adjusted temperature, to control grain size, or some other microstructural feature.

Subsequent fabrication of these as-supplied materials can again involve hot- or cold-working, as discussed in the Hot-working and Cold-working sections of this guide. Again, working often involves steps, with intermediate annealing (normally solution-annealing for the CRA materials) treatments to restore ductility. Beyond that, fabricated components will require a final anneal (normally a solution-anneal for the CRA materials), to restore optimum properties prior to use, or (in the case of the age-hardenable alloys) to prepare them for age-hardening.

Applicable to:
Corrosion-resistant Alloys

The compositions of the corrosion-resistant alloys (CRA) comprise a nickel base, substantial additions of chromium and/or molybdenum (in some cases partially replaced by tungsten), small additions such as copper (to enhance resistance to certain media) and iron (to allow the use of less expensive raw materials), and minor additions such as aluminum and manganese, which help remove deleterious elements such as oxygen and sulfur, during melting. As-supplied, they generally exhibit single phase (face-centered cubic, or gamma) wrought microstructures.

In most cases, the presence of a single phase microstructure in as-supplied (CRA) materials is due to a high temperature, solution-annealing treatment, followed by quenching (rapid cooling), to “lock-in” the high-temperature structure. Left to cool slowly, most of these alloys would contain second phases (albeit in small amounts), commonly within the structural grain boundaries, as a result of the fact that the combined contents of the alloying additions exceed their solubility limits.

This is exacerbated by the fact that, despite sophisticated melting techniques and procedures, traces of unwanted elements (with very low solubility), such as carbon and silicon, can be present. Fortunately, solution-annealing, followed by quenching (by water or cold gas), solves this problem also.

The corrosion-resistant alloys are usually supplied in the solution-annealed condition, and their normal solution-annealing temperatures are given in the table below. They represent temperatures at which phases other than gamma (and, in rare cases, primary carbides and/or nitrides) dissolve, yet provide grain sizes within the range known to impart good mechanical properties. Primary carbides and/or nitrides are seen in C-4 alloy, due to the presence of titanium.

In the case of the corrosion-resistant alloys (CRA), the terms solution-annealed and mill-annealed (MA) are generally synonymous; however, the temperatures used in continuous hydrogen-annealing furnaces (in sheet production) are adjusted to compensate for the line speeds (hence time at temperature).

Solution-annealing Temperatures of the Corrosion-resistant Alloys (CRA)

Alloy Solution-annealing Temperature* Type of Quench
- °F °C -
B-3® 1950 1066 WQ or RAC
C-4 1950 1066 WQ or RAC
C-22® 2050 1121 WQ or RAC
C-22HS® 1975 1079 WQ or RAC
C-276 2050 1121 WQ or RAC
C-2000® 2100 1149 WQ or RAC
G-30® 2150 1177 WQ or RAC
G-35® 2050 1121 WQ or RAC
HYBRID-BC1® 2100 1149 WQ or RAC

*Plus or Minus 25°F (14°C)
WQ = Water Quench (Preferred); RAC = Rapid Air Cool

There are no specific rules regarding the times required to heat up, then anneal, the corrosion-resistant alloys (CRA), since there are many types of furnace, involving different modes of loading, unloading, and operation. There are only general guidelines.

The temperature of the work-piece being annealed should be measured with an attached thermocouple, and recording of the annealing time should begin only when the entire section of the work-piece has reached the recommended annealing temperature. It should be remembered that the center of the section takes longer to reach the annealing temperature than the surface.

The general guidelines regarding time are:

  • Normally, once the whole of the workpiece is at the annealing temperature, the annealing time should be between 10 and 30 minutes, depending upon the section thickness.
  • The shorter times within this range should be used for thin sheet components.
  • The longer times should be used for thick (heavier) sections.

Rapid cooling is essential after annealing, to prevent the nucleation and growth of deleterious second phase precipitates in the microstructure, particularly at the grain boundaries. Water quenching is preferred, and highly recommended for materials thicker than 3/8 in (9.5 mm). Rapid air cooling has been used for thin sections. The time between removal from the furnace and the start of quenching must be as short as possible (and certainly less than three minutes).

Special precautions are necessary with B-3® alloy. Although more stable than other nickel-molybdenum alloys (particularly its predecessor, B-2® alloy), it is still prone to significant, deleterious, microstructural changes in the temperature range 1100-1500°F (593-816°C), especially after being cold-worked. Thus, care must be taken to avoid exposing B-3® alloy to temperatures within this range for any length of time. B-3®alloy should be annealed in furnaces pre-heated to the annealing temperature (1950°F/1066°C), and with sufficient thermal capacity to ensure rapid recovery of the temperature after loading of the furnace with the B-3® work-piece.

One of the potential problems associated with these microstructural changes (which can occur during heating to the annealing temperature) in the nickel-molybdenum (B-type) alloys is cracking due to residual stresses, in cold-worked material. Shot peening of the knuckle radius and straight flange regions of cold-formed heads, to lower residual tensile stress patterns, has been found to be very beneficial in avoidance of such problems. Cold or hot formed heads should always be annealed after forming, regardless of forming strain level. This is especially important if the material is to be subsequently welded.

Applicable To:
High-temperature Alloys

The high-temperature alloys (HTA), whether based on nickel, cobalt, or a mixture of nickel, cobalt, and iron, are compositionally much more complicated. However, as in the CRA alloys, chromium is an important alloying element, enabling the formation of protective, surface films (particularly oxides) in hot gases.

Large atoms such as molybdenum and tungsten are used to provide solid-solution strength to many of the high-temperature alloys. Those relying on age-hardening for strength include significant quantities of elements such as aluminum, titanium, and niobium (columbium), which can form extremely fine precipitates of second phases (“gamma prime” and “gamma double prime”) known to be very effective strengtheners.

Aluminum can play another role in the high temperature alloys, and that is to modify the protective films (oxides, in particular) that form on the surfaces of these materials at high-temperatures, in the presence of oxygen, etc. Indeed, aluminum oxide is very adherent, stable, and protective.

Unlike the CRA materials, in which carbon is generally a negative actor, the high-temperature HAYNES® and HASTELLOY® (HTA) alloys rely upon deliberate carbon additions, or rather the carbides they induce in the microstructures, to provide the necessary levels of strength (particularly creep strength) for high-temperature service. In some cases, these carbides form during solidification of the materials (primary carbides). In other cases, they form during high-temperature exposure, in the solid state (secondary carbides).

As a consequence of the need for specific carbide types and morphologies in the HTA materials, annealing is a much more complicated subject, especially between steps in the manufacturing and fabrication processes.

The high-temperature HAYNES® and HASTELLOY® alloys are normally supplied in the solution-annealed condition, which is attained by heat treatment at the following temperatures (or within the specified ranges):

Solution-annealing Temperatures of the High-temperature Alloys (HTA)

Alloy Solution-annealing Temperature/Range Type of Quench
- °F °C -
25 2150-2250 1177-1232 WQ or RAC
75 1925* 1052* WQ or RAC
188 2125-2175 1163-1191 WQ or RAC
214® 2000 1093 WQ or RAC
230® 2125-2275 1163-1246 WQ or RAC
242® 1900-2050 1038-1121 WQ or RAC
244® 2000-2100 1093-1149 WQ or RAC
263 2100 + 25 1149 + 14 WQ or RAC
282® 2050-2100 1121-1149 WQ or RAC
556® 2125-2175 1163-1191 WQ or RAC
625 2000-2200 1093-1204 WQ or RAC
718 1700-1850** 927-1010** WQ or RAC
HR-120® 2150-2250 1177-1232 WQ or RAC
HR-160® 2025-2075 1107-1135 WQ or RAC
HR-224®     WQ or RAC
HR-235® 2075-2125 1135-1163 WQ or RAC
MULTIMET® 2150 1177 WQ or RAC
N 2150 1177 WQ or RAC
R-41 2050 1121 WQ or RAC
S 1925-2075 1052-1135 WQ or RAC
W 2165 1185 WQ or RAC
WASPALOY 1975 1079 WQ or RAC
X 2125-2175 1163-1191 WQ or RAC
X-750 1900* 1038* WQ or RAC

WQ = Water Quench (Preferred); RAC = Rapid Air Cool
*Bright (Hydrogen) Annealing Temperature
**Not Strictly a Solution-annealing Temperature Range (More a Preparatory Annealing Temperature Range)

In the solution-annealed condition, the microstructures of the high-temperature alloys (HTA) generally consist of primary carbides dispersed in a gamma phase (face-centered cubic) matrix, with essentially clean (precipitate-free) grain boundaries. For the solid-solution strengthened alloys, this is usually the optimum condition for both high-temperature service, and for room temperature fabricability.

Although the HAYNES® and HASTELLOY® alloys should not be subjected to stress relief treatments at the sort of temperatures used for the steels and stainless steels, for fear of causing the precipitation of undesirable second phases (particularly in the alloy grain boundaries), some lower annealing temperatures have been used for the high-temperature alloys (HTA) between processing steps, to restore the ductility of partially-fabricated workpieces. These so-called intermediate annealing temperatures should be used with caution, since they too are likely to result in the aforementioned grain boundary precipitation. Some minimum, intermediate annealing temperatures are given in the following table (for selected solid-solution strengthened HTA materials):

Minimum Intermediate Annealing Temperatures (HTA)

Alloy Minimum Intermediate Annealing Temperature
- °F °C
25 2050 1121
188 2050 1121
230® 2050 1121
556® 1900 1038
625 1700 927
HR-120® 1950 1066
HR-160® 1950 1066
S 1750 954
X 1850 1010

Whether an intermediate annealing temperature (rather than a solution-annealing temperature) is appropriate between processing steps will depend upon the alloy and the effects of the lower temperature upon microstructure, and upon the nature of the subsequent operation. These issues must be studied carefully, and advice sought.

Annealing During Cold (or Warm) Forming

Applicable To:
High-temperature Alloys

The response of the HAYNES® and HASTELLOY® high-temperature alloys (HTA) to heat treatment is very dependent upon the condition of the material prior to the treatment. When the material is not in a cold- or warm-worked condition, the principal response is usually a change in the amount and morphology of the secondary carbide phases. Other minor effects might occur, but the grain structure normally remains the same (in the absence of prior cold or warm work).

When these alloys have been subjected to cold- or warm-work, the application of a solution or intermediate anneal will almost always alter the grain structure. Moreover, the amount of prior cold- or warm-work will significantly affect the grain structure, and consequently the mechanical properties of the material.

The following table indicates the effects of heat-treatments (of 5 minutes duration) at various temperatures upon the grain sizes of sheets of several high temperature alloys, subjected to different levels of cold-work.

Effects of Cold-work and Heat Treatment Temperature on Grain Size

Cold-work Heat TreatmentTemperature Cold-work
% °F °C 25 230® 556® X
0 None 3.5-4 3.5-4 3.5-4 3.5-4
10 1850 3.5-4 3.5-4 3.5-4 NR 3.5-4
1950 3.5-4 3.5-4 3.5-4 NR 3.5-4
2050 3.5-4 3.5-4 3.5-4 5-5.5 3.5-4
2150 3.5-4 3.5-4 3.5-4 5-5.5 3.5-4
2250 3.5-4 3.5-4 3.5-4 NA 3.5-4
15 1950 3.5-4 3.5-4 3.5-4 NA 3.5-4
2050 3.5-4 3.5-4 3.5-4 NA 3.5-4
2150 3.5-4 3.5-4 3.5-4 NA 3.5-4
2250 3.5-4 3.5-4 3.5-4 NA 3.5-4
20 1850 3.5-4 3.5-4 3.5-4 NR 3.5-4
1950 3.5-4 3.5-4 3.5-4 NR 3.5-4
2050 3.5-4 3.5-4 3.5-4 7.5-8.5 3.5-4
2150 3.5-4 3.5-4 3.5-4 6-6.5 3.5-4
2250 3.5-4 3.5-4 3.5-4 NA 3.5-4
25 1950 3.5-4 3.5-4 3.5-4 NA 3.5-4
2050 3.5-4 3.5-4 3.5-4 NA 3.5-4
2150 3.5-4 3.5-4 3.5-4 NA 3.5-4
2250 3.5-4 3.5-4 3.5-4 NA 3.5-4
30 1850 3.5-4 3.5-4 3.5-4 NFR 3.5-4
1950 3.5-4 3.5-4 3.5-4 7.5-9.5 3.5-4
2050 3.5-4 3.5-4 3.5-4 7-7.5 3.5-4
2150 3.5-4 3.5-4 3.5-4 4.5-6.5 3.5-4
2250 3.5-4 3.5-4 3.5-4 NA 3.5-4
40 1850 3.5-4 3.5-4 3.5-4 7.5-9.5 3.5-4
1950 3.5-4 3.5-4 3.5-4 8-9.5 3.5-4
2050 3.5-4 3.5-4 3.5-4 7-9 3.5-4
2150 3.5-4 3.5-4 3.5-4 4.5-6.5 3.5-4
2250 3.5-4 3.5-4 3.5-4 NA 3.5-4
50 1850 3.5-4 3.5-4 3.5-4 9-10 3.5-4
1950 3.5-4 3.5-4 3.5-4 8.5-10 3.5-4
2050 3.5-4 3.5-4 3.5-4 8-9.5 3.5-4
2150 3.5-4 3.5-4 3.5-4 5.5-6 3.5-4
2250 3.5-4 3.5-4 3.5-4 NA 3.5-4

NA=Not Available
NR= No Recrystallization Observed
NFR=Not Fully Recrystallized

The effects of cold-work plus heat treatment at various temperatures upon the mechanical properties of several solid solution strengthened, high temperature HAYNES® and HASTELLOY® alloys are shown in the following tables and figures.

Effects of Cold-work and Heat Treatment Temperature on the Room Temperature Mechanical Properties of HAYNES® 25 Sheet

Cold-work Heat Treatment* Temperature 0.2% Offset Yield Strength Ultimate Tensile Strength Elongation Hardness
% °F °C ksi MPa ksi MPa % HRC
No Cold-work No Heat Treatment 68 469 144 993 58 24
10 No Heat Treatment 124 855 182 1255 37 36
15 No Heat Treatment 149 1027 178 1227 28 40
20 No Heat Treatment 151 1041 193 1331 18 42
25 No Heat Treatment 184 1269 232 1600 15 44
10 1950 1066 98 676 163 1124 39 32
15 1950 1066 91 627 167 1151 44 30
20 1950 1066 96 662 171 1179 41 32
25 1950 1066 89 614 169 1165 44 32
10 2050 1121 74 510 157 1082 53 27
15 2050 1121 79 545 161 1110 52 28
20 2050 1121 82 565 165 1138 48 31
25 2050 1121 83 572 166 1145 48 30
10 2150 1177 67 462 148 1020 63 21
15 2150 1177 74 510 156 1076 55 26
20 2150 1177 72 496 154 1062 59 26
25 2150 1177 69 476 149 1027 62 25
10 2250 1232 69 476 144 993 64 95
15 2250 1232 64 441 142 979 68 97
20 2250 1232 62 427 135 931 69 97
25 2250 1232 61 421 138 951 70 96

*5 Minutes Duration + Rapid Air Cool
Tensile Results are Averages of 2 or More Tests
HRC= Hardness Rockwell “C”

Effects of Cold-work and Heat Treatment Temperature on the Room Temperature Mechanical Properties of HAYNES® 188 Sheet

Cold-work Heat Treatment* Temperature 0.2% Offset Yield Strength Ultimate Tensile Strength Elongation Hardness
% °F °C ksi MPa ksi MPa % HR BW/C
No Cold-work No Heat Treatment 67 462 137 945 54 98 HRBW
10 No Heat Treatment 106 731 151 1041 45 32 HRC
20 No Heat Treatment 133 917 166 1145 28 37 HRC
30 No Heat Treatment 167 1151 195 1344 13 41 HRC
40 No Heat Treatment 177 1220 215 1482 10 44 HRC
10 1950 1066 91 627 149 1027 41 30 HRC
20 1950 1066 88 607 153 1055 41 28 HRC
30 1950 1066 84 579 158 1089 41 30 HRC
40 1950 1066 91 627 163 1124 40 31 HRC
10 2050 1121 65 448 143 986 50 22 HRC
20 2050 1121 71 490 149 1027 47 25 HRC
30 2050 1121 80 552 155 1069 44 28 HRC
40 2050 1121 87 600 159 1096 43 30 HRC
10 2150 1177 62 427 140 965 55 96 HRBW
20 2150 1177 65 448 141 972 53 97 HRBW
30 2150 1177 67 462 143 986 52 99 HRBW
40 2150 1177 64 441 141 972 56 97 HRBW
10 2250 1232 59 407 132 910 59 95 HRBW
20 2250 1232 58 400 130 896 63 94 HRBW
30 2250 1232 58 400 131 903 63 93 HRBW
40 2250 1232 58 >400 132 910 62 93 HRBW

*5 Minutes Duration + Rapid Air Cool
Tensile Results are Averages of 2 or More Tests
HRBW = Hardness Rockwell “B”, Tungsten Indentor
HRC = Hardness Rockwell “C”

Effects of Cold-work and Heat Treatment Temperature on the Room Temperature Mechanical Properties of HAYNES® 230® Sheet

Cold-work Heat Treatment* Temperature 0.2% OffsetYield Strength Ultimate Tensile Strength Elongation Hardness
% °F °C ksi MPa ksi MPa % HR BW/C
No Cold-work No Heat Treatment 62 427 128 883 47 95 HRBW
10 No Heat Treatment 104 717 145 1000 32 28 HRC
20 No Heat Treatment 133 917 164 1131 17 35 HRC
30 No Heat Treatment 160 1103 188 1296 10 39 HRC
40 No Heat Treatment 172 1186 202 1393 8 40 HRC
50 No Heat Treatment 185 1276 215 1482 6 42 HRC
10 1950 1066 92 634 144 993 33 24 HRC
20 1950 1066 81 558 142 979 36 26 HRC
30 1950 1066 76 524 142 979 36 99 HRBW
40 1950 1066 81 558 146 1007 32 23 HRC
50 1950 1066 86 593 148 1020 35 24 HRC
10 2050 1121 81 558 139 958 37 98 HRBW
20 2050 1121 65 448 136 938 39 97 HRBW
30 2050 1121 72 496 140 965 38 99 HRBW
40 2050 1121 76 524 142 979 36 99 HRBW
50 2050 1121 81 558 144 993 36 23 HRC
10 2150 1177 56 386 130 896 44 92 HRBW
20 2150 1177 64 441 134 924 40 96 HRBW
30 2150 1177 70 483 138 951 39 98 HRBW
40 2150 1177 73 503 139 958 38 98 HRBW
50 2150 1177 72 496 138 951 39 98 HRBW
10 2250 1232 52 359 125 862 47 92 HRBW
20 2250 1232 57 393 128 883 45 92 HRBW
30 2250 1232 54 372 126 869 48 92 HRBW
40 2250 1232 53 365 126 869 47 91 HRBW
50 2250 1232 55 379 128 883 46 89 HRBW

*5 Minutes Duration + Rapid Air Cool
Tensile Results are Averages of 2 or More Tests
HRBW = Hardness Rockwell “B”, Tungsten Indentor
HRC = Hardness Rockwell “C”

Effects of Cold-work and Heat Treatment Temperature on the Room Temperature Mechanical Properties of HAYNES® 625 Sheet

Cold-work Heat Treatment* Temperature 0.2% Offset Yield Strength Ultimate Tensile Strength Elongation Hardness
% °F °C ksi MPa ksi MPa % HR BW/C
No Cold-work No Heat Treatment 70 483 133 917 46 97 HRBW
10 No Heat Treatment 113 779 151 1041 30 32 HRC
20 No Heat Treatment 140 965 169 1165 16 37 HRC
30 No Heat Treatment 162 1117 191 1317 11 40 HRC
40 No Heat Treatment 178 1227 209 1441 8 42 HRC
50 No Heat Treatment 184 1269 223 1538 5 45 HRC
10 1850 1010 63 434 134 924 46 NA
20 1850 1010 71 490 138 951 44 NA
30 1850 1010 78 538 141 972 44 NA
40 1850 1010 82 565 141 972 42 NA
50 1850 1010 82 565 141 972 42 NA
10 1950 1066 61 421 133 917 46 NA
20 1950 1066 71 490 137 945 45 NA
30 1950 1066 77 531 140 965 44 NA
40 1950 1066 83 572 142 979 42 NA
50 1950 1066 82 565 141 972 42 NA
10 2050 1121 58 400 128 883 50 NA
20 2050 1121 67 462 135 931 46 NA
30 2050 1121 58 400 127 876 52 NA
40 2050 1121 72 496 137 945 44 NA
50 2050 1121 61 421 130 896 50 NA
10 2150 1177 52 359 122 841 55 NA
20 2150 1177 54 372 124 855 55 NA
30 2150 1177 53 365 122 841 56 NA
40 2150 1177 52 359 122 841 55 NA
50 2150 1177 51 352 119 820 58 NA

*5 Minutes Duration + Rapid Air Cool
Tensile Results are Averages of 2 or More Tests
NA=Not Available
HRBW = Hardness Rockwell “B”, Tungsten Indentor
HRC = Hardess Rockwell “C”

Effects of Cold-work and Heat Treatment Temperature on the Room Temperature Mechanical Properties of HAYNES HR-120® Sheet

Cold-work Heat-treatment* Temperature 0.2% Offset Yield Strength Ultimate Tensile Strength Elongation Hardness
% °F °C ksi MPa ksi MPa % HR BW/C
No Cold-work No Heat Treatment 60 414 113 779 39 93 HRBW
10 No Heat Treatment 103 710 126 869 26 27 HRC
20 No Heat Treatment 129 889 144 993 11 32 HRC
30 No Heat Treatment 143 986 157 1082 6 34 HRC
40 No Heat Treatment 159 1096 179 1234 6 35 HRC
50 No Heat Treatment 166 1145 186 1282 5 36 HRC
10 1950 1066 52 359 109 752 38 89 HRBW
20 1950 1066 55 379 111 765 38 92 HRBW
30 1950 1066 60 414 115 793 38 93 HRBW
40 1950 1066 65 448 117 807 37 93 HRBW
50 1950 1066 67 462 118 814 34 93 HRBW
10 2050 1121 49 338 108 745 47 88 HRBW
20 2050 1121 53 365 117 807 41 90 HRBW
30 2050 1121 55 379 112 772 40 91 HRBW
40 2050 1121 58 400 114 786 37 91 HRBW
50 2050 1121 59 407 114 786 37 89 HRBW
10 2150 1177 49 338 109 752 43 86 HRBW
20 2150 1177 50 345 109 752 42 87 HRBW
30 2150 1177 51 352 110 758 43 88 HRBW
40 2150 1177 50 345 111 765 38 86 HRBW
50 2150 1177 50 345 110 758 39 82 HRBW
10 2250 1232 46 317 106 731 46 84 HRBW
20 2250 1232 44 303 104 717 47 80 HRBW
30 2250 1232 44 303 103 710 48 80 HRBW
40 2250 1232 44 303 104 717 45 81 HRBW
50 2250 1232 44 303 104 717 43 83 HRBW

*5 Minutes Duration + Rapid Air Cool
Tensile Results are Averages of 2 or More Tests
HRBW = Hardness Rockwell “B”, Tungsten Indentor
HRC = Hardness Rockwell “C”

Effects of Cold-work and Heat Treatment Temperature on the Room Temperature Mechanical Properties of HASTELLOY® X Sheet

Cold-work Heat Treatment* Temperature 0.2% Offset Yield Strength Ultimate Tensile Strength Elongation Hardness
% °F °C ksi MPa ksi MPa % HR BW/C
No Cold-work No Heat Treatment 57 393 114 786 46 89 HRBW
10 No Heat Treatment 96 662 129 889 29 25 HRC
20 No Heat Treatment 122 841 147 1014 15 31 HRC
30 No Heat Treatment 142 979 169 1165 10 35 HRC
40 No Heat Treatment 159 1096 186 1282 8 37 HRC
50 No Heat Treatment 171 1179 200 1379 7 39 HRC
10 1850 1010 76 524 125 862 32 98 HRBW
20 1850 1010 91 627 132 910 27 23 HRC
30 1850 1010 87 600 135 931 28 99 HRBW
40 1850 1010 77 531 133 917 32 98 HRBW
50 1850 1010 81 558 135 931 33 99 HRBW
10 1950 1066 74 510 122 841 34 93 HRBW
20 1950 1066 66 455 124 855 35 96 HRBW
30 1950 1066 63 434 126 869 36 96 HRBW
40 1950 1066 70 483 129 889 35 96 HRBW
50 1950 1066 74 510 129 889 34 97 HRBW
10 2050 1121 53 365 119 820 42 89 HRBW
20 2050 1121 56 386 121 834 40 91 HRBW
30 2050 1121 61 421 123 848 39 94 HRBW
40 2050 1121 65 448 125 862 37 94 HRBW
50 2050 1121 67 462 125 862 38 94 HRBW
10 2150 1177 45 310 109 752 49 94 HRBW
20 2150 1177 47 324 111 765 47 87 HRBW
30 2150 1177 49 338 113 779 46 86 HRBW
40 2150 1177 46 317 110 758 48 85 HRBW
50 2150 1177 46 317 110 758 48 84 HRBW

*5 Minutes Duration + Rapid Air Cool
Tensile Results are Averages of 2 or More Tests
HRBW = Hardness Rockwell “B”, Tungsten Indentor
HRC = Hardness Rockwell “C”

Age-hardening Treatments for Age-hardenable Alloys

Applicable to:
Corrosion-resistant Alloys
High-temperature Alloys

Alloy No. of Steps Treatment
C-22HS® 2 16 hours at 1300°F (704°C), furnace cool to 1125°F (607°C),hold at 1125°F for 32 hours, air cool
242® 1 48 hours* at 1200°F (649°C), air cool
244® 2 16 hours at 1400°F (760°C), furnace cool to 1200°F (649°C),hold at 1200°F for 32 hours, air cool
263 1 8 hours at 1472°F (800°C), air cool
282® 2 2 hours at 1850°F (1010°C), rapid air cool or air cool,followed by 8 hours at 1450°F (788°C), air cool
718 2 8 hours at 1325°F (718°C), furnace cool to 1150°F (621°C),hold at 1150°F for 8 hours, air cool
R-41 1 16 hours at 1400°F (760°C), air cool
WASPALOY 3 2 hours at 1825°F (996°C), air cool,followed by 4 hours at 1550°F (843°C), air cool,followed by 16 hours at 1400°F (760°C), air cool
X-750 2 8 hours at 1350°F (732°C), furnace cool to 1150°F (621°C),hold at 1150°F for 8 hours, air cool

*Minimum

To harden/strengthen those materials capable of age hardening, the following treatments are usually applied, assuming the starting material is in the solution-annealed condition. Alternate hardening/strengthening treatments are possible for some of these alloys, depending upon the intended applications and the required strength levels. Please contact Haynes International for details.

Heating and Cooling Rates

Applicable to:
Corrosion-resistant Alloys
High-temperature Alloys
Wear & Corrosion-resistant Alloy

Heating and cooling of the HAYNES® and HASTELLOY® alloys should generally be as rapid as possible. This is to minimize the precipitation of second phase particles (notably carbides, in the case of the high-temperature alloys) in their microstructures at intermediate temperatures. Rapid heating also preserves stored energy from cold- or warm-work, which can be important to re-crystallization and/or grain growth at the annealing temperature. Indeed, slow heating can result in a finer than desirable grain size, particularly in thin-section components, given limited time at the annealing temperature.

Rapid cooling after solution-annealing is critical, again to prevent the precipitation of second phases, particularly in the microstructural grain boundaries in the approximate temperature range 1000°F to 1800°F (538°C to 982°C). Where practical, and where it is unlikely to cause distortion, a water quench is preferred. It will be noted that cooling from age-hardening treatments (in the case of the age-hardenable, high-temperature alloy components) usually involves air cooling.

The sensitivity of individual alloys to slow cooling varies, but as an example of the effect of cooling rate upon properties, the following table shows the creep life of HAYNES® 188 alloy as a function of the cooling process.

Effect of Cooling Rate upon the Creep Life of HAYNES® 188 Sheet

Cooling Process after Solution-annealing at 2150°F (1177°C) Time to 0.5% Creep for1600°F/7 ksi (871°C/48 MPa) Test
Water Quench 148 h
Air Cool 97 h
Furnace Cool to 1200°F (649°C), then Air Cool 48 h

Holding Time

The times at temperature required for annealing are governed by the need to ensure that all metallurgical reactions are complete, uniformly and throughout the component. As mentioned earlier, the general rules for holding time are at least 30 minutes per inch of thickness in the case of massive workpieces and components, and 10 to 30 minutes (once the entire piece is uniformly at the required annealing temperature) for less massive workpieces and components, depending upon section thickness. Extremely long holding times (such as overnight) are not recommended, since they can be harmful to alloy microstructures and properties.

For continuous annealing of strip or wire, several minutes at temperature will usually suffice.

Time in the furnace will depend on the furnace type and capacity, and the work-piece/component thickness and geometry. To determine when the entire work-piece has reached the required annealing temperature, measurements should be taken using thermocouples attached to the work-piece, where possible.

Use of a Protective Atmosphere

Most of the HAYNES® and HASTELLOY® alloys can be annealed in oxidizing environments, but will form adherent oxide scales which should normally be removed prior to further processing. For details on scale removal, please refer to the the section on Descaling and Pickling.

Some HAYNES® and HASTELLOY® alloys contain low chromium contents, and require annealing in neutral or slightly reducing atmospheres.

When a bright finish (free from oxide scales) is required, a protective atmosphere, such as low dew point hydrogen, is necessary. Atmospheres of argon and helium have been used, although pronounced tinting is possible with these alternate gases, due to oxygen or water vapor contamination. Annealing in nitrogen or cracked ammonia is not usually recommended, but may be acceptable in certain cases.

Vacuum annealing is generally acceptable, but again some tinting is possible, depending on the vacuum pressure and temperature. Selection of the gas used for forced gas cooling is important: Helium is normally preferred, followed by argon and nitrogen (for some alloys).

Selection of Heat-Treating Equipment

Most types of industrial furnace are suitable for heat treating the HAYNES® and HASTELLOY® alloys. However, induction heating is not normally recommended, due to inadequate control of the temperature and lack of uniform heating. Heating by torches, welding equipment, and the like is unacceptable. Flame impingement of any type during heat treatment should be avoided.