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HAYNES® Alloys

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.  

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.

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 Treatment
Temperature

ASTM Grain Size Produced

%

°F

°C

25

230®

556®

X

0

None

3.5-4

5-6

5-6

4-5

10

1850

1010

NA

NA

NR

NR

1950

1066

NR

NR

NR

NR

2050

1121

NR

NFR

5-5.5

5-7

2150

1177

4-4.5

4-7

5-5.5

NA

2250

1232

3-4.5

6.5-7

NA

NA

15

1950

1066

7

NA

NA

NA

2050

1121

6-7

NA

NA

NA

2150

1177

5-7

NA

NA

NA

2250

1232

3-4.5

NA

NA

NA

20

1850

1010

NA

NA

NR

NFR

1950

1066

7-8

NFR

NR

NFR

2050

1121

7-8

8-8.5

7.5-8.5

7-8

2150

1177

4.5-7

7.5-8

6-6.5

NA

2250

1232

2.5-4.5

7-7.5

NA

NA

25

1950

1066

7.5-8

NA

NA

NA

2050

1121

7.5-8

NA

NA

NA

2150

1177

4

NA

NA

NA

2250

1232

3.5

NA

NA

NA

30

1850

1010

NA

NA

NFR

NFR

1950

1066

NA

8-9

7.5-9.5

8-10

2050

1121

NA

9-10

7-7.5

7.5-9.5

2150

1177

NA

8.5-9

4.5-6.5

NA

2250

1232

NA

6-7

NA

NA

40

1850

1010

NA

NA

7.5-9.5

8-9

1950

1066

NA

9.5-10

8-9.5

8-10

2050

1121

NA

9-10

7-9

9.5-10

2150

1177

NA

8.5-9

4.5-6.5

NA

2250

1232

NA

4-7

NA

NA

50

1850

1010

NA

NA

9-10

8.5-10

1950

1066

NA

9-10

8.5-10

8.5-10

2050

1121

NA

9-10

8-9.5

8.5-10

2150

1177

NA

9-9.5

5.5-6

NA

2250

1232

NA

5.5-6.5

NA

NA

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"

fabheat-treatment

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 B/C

No Cold-work

No Heat Treatment

67

462

137

945

54

98 HRB

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 HRB

20

2150

1177

65

448

141

972

53

97 HRB

30

2150

1177

67

462

143

986

52

99 HRB

40

2150

1177

64

441

141

972

56

97 HRB

10

2250

1232

59

407

132

910

59

95 HRB

20

2250

1232

58

400

130

896

63

94 HRB

30

2250

1232

58

400

131

903

63

93 HRB

40

2250

1232

58

400

132

910

62

93 HRB

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

heat-treatmentyieldstrength

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% Offset

Yield Strength

Ultimate

Tensile Strength

Elongation

Hardness

%

°F

°C

ksi

MPa

ksi

MPa

%

HR B/C

No Cold-work

No Heat Treatment

62

427

128

883

47

95 HRB

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 HRB

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 HRB

20

2050

1121

65

448

136

938

39

97 HRB

30

2050

1121

72

496

140

965

38

99 HRB

40

2050

1121

76

524

142

979

36

99 HRB

50

2050

1121

81

558

144

993

36

23 HRC

10

2150

1177

56

386

130

896

44

92 HRB

20

2150

1177

64

441

134

924

40

96 HRB

30

2150

1177

70

483

138

951

39

98 HRB

40

2150

1177

73

503

139

958

38

98 HRB

50

2150

1177

72

496

138

951

39

98 HRB

10

2250

1232

52

359

125

862

47

92 HRB

20

2250

1232

57

393

128

883

45

92 HRB

30

2250

1232

54

372

126

869

48

92 HRB

40

2250

1232

53

365

126

869

47

91 HRB

50

2250

1232

55

379

128

883

46

89 HRB

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

fabheattreatment230

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 B/C

No Cold-work

No Heat Treatment

70

483

133

917

46

97 HRB

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
HRB= Hardness Rockwell "B"
HRC= Hardess Rockwell "C"

heattreament625

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 B/C

No Cold-work

No Heat Treatment

60

414

113

779

39

93 HRB

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 HRB

20

1950

1066

55

379

111

765

38

92 HRB

30

1950

1066

60

414

115

793

38

93 HRB

40

1950

1066

65

448

117

807

37

93 HRB

50

1950

1066

67

462

118

814

34

93 HRB

10

2050

1121

49

338

108

745

47

88 HRB

20

2050

1121

53

365

117

807

41

90 HRB

30

2050

1121

55

379

112

772

40

91 HRB

40

2050

1121

58

400

114

786

37

91 HRB

50

2050

1121

59

407

114

786

37

89 HRB

10

2150

1177

49

338

109

752

43

86 HRB

20

2150

1177

50

345

109

752

42

87 HRB

30

2150

1177

51

352

110

758

43

88 HRB

40

2150

1177

50

345

111

765

38

86 HRB

50

2150

1177

50

345

110

758

39

82 HRB

10

2250

1232

46

317

106

731

46

84 HRB

20

2250

1232

44

303

104

717

47

80 HRB

30

2250

1232

44

303

103

710

48

80 HRB

40

2250

1232

44

303

104

717

45

81 HRB

50

2250

1232

44

303

104

717

43

83 HRB

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

heattreatmentHR120

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 B/C

No Cold-work

No Heat Treatment

57

393

114

786

46

89 HRB

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 HRB

20

1850

1010

91

627

132

910

27

23 HRC

30

1850

1010

87

600

135

931

28

99 HRB

40

1850

1010

77

531

133

917

32

98 HRB

50

1850

1010

81

558

135

931

33

99 HRB

10

1950

1066

74

510

122

841

34

93 HRB

20

1950

1066

66

455

124

855

35

96 HRB

30

1950

1066

63

434

126

869

36

96 HRB

40

1950

1066

70

483

129

889

35

96 HRB

50

1950

1066

74

510

129

889

34

97 HRB

10

2050

1121

53

365

119

820

42

89 HRB

20

2050

1121

56

386

121

834

40

91 HRB

30

2050

1121

61

421

123

848

39

94 HRB

40

2050

1121

65

448

125

862

37

94 HRB

50

2050

1121

67

462

125

862

38

94 HRB

10

2150

1177

45

310

109

752

49

94 HRB

20

2150

1177

47

324

111

765

47

87 HRB

30

2150

1177

49

338

113

779

46

86 HRB

40

2150

1177

46

317

110

758

48

85 HRB

50

2150

1177

46

317

110

758

48

84 HRB

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

heattreatmentX

Age-hardening Treatments for Age-hardenable 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

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 for
1600°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.

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