HIGH TEMPERATURE PROPERTIES

Stainless steels have good strength and good resistance to corrosion and oxidation at elevated temperatures. Stainless steels are used at temperatures up to 1700° F for 304 and 316 and up to 2000 F for the high temperature stainless grade 309(S) and up to 2100° F for 310(S). Stainless steel is used extensively in heat exchangers, super-heaters, boilers, feed water heaters, valves and main steam lines as well as aircraft and aerospace applications.

Figure 1 (below) gives a broad concept of the hot strength advantages of stainless steel in comparison to low carbon unalloyed steel. Table 1 (below) shows the short term tensile and yield strength vs temperature. Table 2 (below) shows the generally accepted temperatures for both intermittent and continuous service.

With time and temperature, changes in metallurgical structure can be expected with any metal. In stainless steel, the changes can be softening, carbide precipitation, or embrittlement. Softening or loss of strength occurs in the 300 series (304, 316, etc.) stainless steels at about 1000° F and at about 900° F for the hardenable 400 (410, 420, 440) series and 800° F for the non-hardenable 400 (409, 430) series (refer to Table 1, below).

Carbide precipitation can occur in the 300 series in the temperature range 800 – 1600° F. It can be deterred by choosing a grade designed to prevent carbide precipitation i.e., 347 (Cb added) or 321 (Ti added). If carbide precipitation does occur, it can be removed by heating above 1900° and cooling quickly.

Hardenable 400 series with greater than 12% chromium as well as the non-hardenable 400 series and the duplex stainless steels are subject to embrittlement when exposed to temperature of 700 – 950° F over an extended period of time. This is sometimes call 885F embrittlement because this is the temperature at which the embrittlement is the most rapid. 885F embrittlement results in low ductility and increased hardness and tensile strengths at room temperature, but retains its desirable mechanical properties at operating temperatures.

Table 1
Short Term Tensile Strength vs Temperature
(in the annealed condition except for 410)

Temperature

304
& TS
ksi

316
YS
ksi

309
& TS
ksi

309S
YS
ksi

310
& TS
ksi

310S
YS
ksi

410*
TS
ksi


YS
ksi

430
TS
ksi


YS
ksi

Room Temp.

84

42

90

45

90

45

110

85

75

50

400°F

82

36

80

38

84

34

108

85

65

38

600°F

77

32

75

36

82

31

102

82

62

36

800°F

74

28

71

34

78

28

92

80

55

35

1000°F

70

26

64

30

70

26

74

70

38

28

1200°F

58

23

53

27

59

25

44

40

22

16

1400°F

34

20

35

20

41

24

---

---

10

8

1600°F

24

18

25

20

26

22

---

---

5

4

* heat treated by oil quenching from 1800° F and tempering at 1200° F

Table 2
Generally Accepted Service Temperatures

Material

Intermittent
Service Temperature

Continuous
Service Temperature

Austenitic

 

 

304

1600°F
(870°C)

1700°F
(925°C)

316

1600°F
(870°C)

1700°F
(925°C)

309

1800°F
(980°C)

2000°F
(1095°C)

310

1900°F
(1035°C)

2100°F
(1150°C)

Martensitic

 

 

410

1500°F
(815°C)

1300°F
(705°C)

420

1350°F
(735°C)

1150°F
(620°C)

Ferritic

 

 

430

1600°F
(870°C)

1500°F
(815°C)

It may seem to be illogical that the "continuous" service temperature would be higher than the "intermittent" service temperature for the 300 series grades. The answer is that intermittent service involves "thermal cycling", which can cause the high temperature scale formed to crack and spall. This occurs because of the difference in the coefficient of expansion between the stainless metal and the scale. As a result of this scaling and cracking, there is a greater deterioration of the surface than will occur if the temperature is continuous. Therefore the suggested intermittent service temperatures are lower. This is not the case for the 400 series (both ferritic and martensitic grades). The reason for this is not known.

Table 3:   High temperature elastic modulus in tension for some stainless steels

Elastic Modulus in Tension GPa (ksi x 1,000)

Common
Name

UNS
No.

20°C
(68°F)

100°C
(212°F)

200°C
(392°F)

300°C
(572°F)

400°C
(754°F)

500°C
(932°F)

Carbon Steel

Carbon steel

G10200

207 (30.0)

Austenitic Stainless Steels

304

S30400

193
(28)

193
(28)

193
(27.9)

187
(27.1)

183
(26.6)

179
(26.0)

321

S32100

193
(28)

193
(28)

193
(28)

188
(27.3)

183
(26.5)

178
(25.8)

347

S34700

200
(29)

194
(28.2)

190
(27.5)

185
(26.8)

180
(26.1)

310S

S31008

200
(29)

194
(28.2)

190
(27.5)

185
(26.8)

181
(26.2)

316L

S31603

200
(29.0)

194
(28.1)

185
(26.9)

177
(25.9)

169
(24.5)

160
(23.2)

317LMN

S31726

200
(29.0)

194
(28.1)

186
(27.0)

179
(26.0)

171
(24.8)

163
(23.6)

AL-6XN
(4)

N08367

28.3
(195)

189
(27.4)

180
(26.1)

172
(24.9)

163
(23.7)

158
(23.0)

Duplex Stainless Steels

 

S32101

200
(29.0)

194
(28.0)

186
(27.0)

180
(26.1)

-

-

2304

S32304

200
(29.0)

190
(27.6)

180
(26.1)

170
(24.7)

160
(23.2)

150
(21.8)

2205

S31803

200
(29.0)

190
(27.6)

180
(26.1)

170
(24.7)

160
(23.2)

150
(21.8)

2205

S32205

200
(29.0)

190
(27.6)

180
(26.1)

170
(24.7)

160
(23.2)

150
(21.8)

 

S32520

205
(29.7)

185
(26.8)

185
(26.8)

170
(24.7)

­-

-

255

S32550

210
(30.5)

200
(29.9)

198
(28.7)

192
(27.8)

182
(26.4)

170
(24.7)

2507

S32750

200
(29.0)

190
(27.6)

180
(26.1)

170
(24.7)

160
(23.2)

150
(21.8)

Table 4: Mean high temperature coefficient of thermal expansion for some stainless steels

Mean Coefficient of Thermal Expansion - Temperature 20°C (68°F) to T
cm/cm/°C x 10-6 (in./in./°F x 10-6)

Common Name

UNS No.

20°C (68°F)

100°C (212°F)

200°C (392°F)

260°C (500°F)

300°C (572°F)

316°C (600°F)

400°C (754°F)

482°C (900°F)

500°C (932°F)

538°C (1000°F)

600°C (1112°F)

649°C (1200°F)

787°C (1450°F)

800°C (1472°F)

871°C (1600°F)

1000°C (1832°F)

Carbon Steel

Carbon steel

G10200

 

12.1 (6.70)

13.0 (7.22)

 

 

 

14
 (7.78)

 

 

 

 

 

 

 

 

 

Austenitic Stainless Steels

201

S20100

 

16.6 (9.2)

 

 

 

18.0 (10.0)

 

 

 

19.6 (10.9)

 

 

 

 

20.3 (11.3)

 

301

S30100

 

16.6 (9.2)

 

 

17.6 (9.8)

 

 

 

18.6 (10.3)

 

 

 

 

 

19.8 (11.0)

 

304L

S30403

 

16.6 (9.2)

 

 

 

 

 

 

 

 

 

 

 

 

19.8 (11.0)

 

305

S30500

 

16.6 (9.2)

 

 

 

 

 

 

 

 

 

 

 

 

19.8 (11.0)

 

321

S32100

 

16.6 (9.2)

 

 

 

 

 

 

17.1 (9.5)

 

18.9 (10.5)

 

 

 

 

20.5 (11.4)

347

S34700

 

16.6 (9.2)

 

 

 

 

 

 

 

 

18.9 (10.5)

 

 

 

 

20.5 (11.4)

309

S30900

 

15.6 (8.7)

 

 

 

 

 

 

17.6 (9.8)

 

 

 

 

 

 

19.4 (10.8)

309S

S30908

 

15.6 (8.7)

 

 

 

 

 

 

17.6 (9.8)

 

 

 

 

 

 

 

310

S31000

 

15.9 (8.8)

 

 

 

 

 

 

17.1 (9.5)

 

 

 

 

 

 

18.9 (10.5)

310S

S31008

 

15.9 (8.8)

 

 

 

 

 

 

17.1 (9.5)

 

 

 

 

 

 

 

316L

S31603

15.7 (8.72)

16.5 (9.16)

16.9 (9.38)

 

17.3 (9.61)

 

17.6 (9.78)

 

18.0 (10.0)

 

 

 

 

 

 

19.5 (10.8)

317L

S31703

 

16.5 (9.2)

 

 

 

 

 

 

18.2 (10.1)

 

 

 

 

 

 

19.5 (10.8)

317LMN

S31726

16.1 (8.94)

16.6 (9.22)

17.2 (9.55)

 

17.8 (9.89)

 

18.5 (10.3)

 

18.2 (10.1)

 

 

 

 

 

 

19.5 (10.8)

904L

N08904

15.0 (8.33)

15.3 (8.50)

15.7 (8.72)

 

16.1 (8.94)

 

16.5 (9.17)

 

16.9 (9.39)

 

 

 

 

 

 

 

 

S31254

 

16.9 (9.40)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

N08367

 

15.3 (8.5)

 

 

 

 

 

 

16.0 (8.9)

 

 

 

 

 

 

 

Ferritic Stainless Steels

409

S40910

 

10.52 (5.84)

 

11.11 (6.12)

 

 

 

11.88 (6.60)

 

 

 

12.34 (6.86)

 

 

 

 

S40920

S40930

405

S40500

 

9.7 (5.39)

10.2 (5.67)

 

 

 

 

 

11.8 (6.56)

 

 

 

 

12.7 (7.06)

 

 

430

S43000

 

10.3 (5.7)

 

 

 

 

 

 

11.2 (6.2)

 

 

 

11.9
(6.6)

 

 

 

434

S43400

 

10.4 (5.8)

 

 

 

 

 

 

 

11.4  (6.3)

 

 

 

 

 

 

439

S43035

 

10.2 (5.6)

 

 

 

 

 

 

11.6 (6.4)

 

 

 

 

12.5  (6.9)

 

13.6 (7.5)

444

S44400

 

 

10.3
(5.7)

 

 

 

 

 

 

 

 

 

 

 

 

 

26-3-3

S44660

 

9.7
(5.4)

10.2
( 5.7)

 

10.5 (5.9)

 

10.8
(6.0)

 

 

 

 

 

 

 

 

 

 

S44735

 

9.4
(5.2)

9.7
(5.4)

 

 

 

 

 

 

 

 

 

 

 

 

 

Martensitic Stainless Steels

410

S41000

 

 

10.8  (6.0)

 

 

 

 

 

 

 

12.5  (7.0)

 

 

 

 

 

420

S42000

 

 

10.8  (6.0)

 

 

 

 

 

 

 

12.5  (7.0)

 

 

 

 

 

440A

S44002

 

 

10.8  (6.0)

 

 

 

 

 

 

 

12.2  (6.8)

 

 

 

 

 

440C

S44004

 

 

10.1  (5.6)

 

 

 

 

 

 

 

 

 

 

 

 

 

Duplex Stainless Steels

 

S32101

 

13.0 (7.22)

13.5 (7.50)

 

14.0 (7.78)

 

 

 

 

 

 

 

 

 

 

 

2304

S32304

 

13.0 (7.22)

13.5 (7.50)

 

14.0 (7.78)

 

14.5 (8.06)

 

15.0 (8.33)

 

 

 

 

 

 

 

2205

S31803

 

13.0 (7.22)

13.5 (7.50)

 

14.0 (7.78)

 

14.5 (8.06)

 

15.0 (8.33)

 

 

 

 

 

 

 

2205

S32205

 

13.0 (7.22)

13.5 (7.50)

 

14.0 (7.78)

 

14.5 (8.06)

 

15.0 (8.33)

 

 

 

 

 

 

 

 

S32520

 

12.5 (6.94)

13.0 (7.22)

 

13.5 (7.50)

 

 

 

 

 

 

 

 

 

 

 

255

S32550

 

12.1 (6.72)

12.6 (7.00)

 

13.0 (7.22)

 

13.3 (7.39)

 

13.6 (7.56)

 

 

 

 

 

 

 

2507

S32750

 

13.0 (7.22)

13.5 (7.50)

 

14.0 (7.78)

 

14.5 (8.06)

 

15.0 (8.33)

 

 

 

 

 

 

 

 

Table 5: High temperature thermal conductivity for some stainless steels

Thermal Conductivity - W/m °C (Btu in/hr ft2 °F)

Common
Name

UNS No.

20°C
(68°F)

100°C
(212°F)

200°C
(392°F)

300°C
(572°F)

400°C
(754°F)

500°C
(932°F)

Carbon Steel

Carbon Steel

G10200

52 (360)

51 (354)

49 (340)

43 (298)

Austenitic Stainless Steels

201

S20100

16.9 (117)

21.4 (148)

304

S30400

16.2 (112)

21.4 (148)

309S

S30908

16.2 (112)

19.4 (135)

310S

S31008

15 (104)

-

-

-

-

19 (132)

316L

S31603

14.0 (97)

14.9 (103)

16.0 (111)

17.3 (120)

18.6 (129)

19.9 (138)

317LMN

S31726

14.0 (97)

-

-

-

-

-

904L

N08904

11.5 (80)

13.1 (91)

15.1 (105)

 

S31254

14.0 (97)

 

N08367

13.7 (95)

Martensitic Stainless Steels

440C

S44004

-

24.2 (168)

-

-

-

-

Duplex Stainless Steels

 

S32101

15.0
(105)

16.0
(110)

17.0
(118)

18.0
(124)

-

-

2304

S32304

16.0
(110)

17.0
(118)

19.0
(132)

20.0
(138)

21.0
(147)

22.0
(153)

2205

S31803

16.0
(110)

17.0
(118)

19.0
(132)

20.0
(138)

21.0
(147)

22.0
(153)

2205

S32205

16.0
(110)

17.0
(118)

19.0
(132)

20.0
(138)

21.0
(147)

22.0
(153)

 

S32520

17.0
(118)

18.0
(124)

19.0
(132)

20.0
(138)

255

S32550

13.5
(94)

15.1
(105)

17.2 (119)

19.1
(133)

20.9
(145)

22.5
(156)

2507

S32750

16.0
(110)

17.0
(118)

19.0
(132)

20.0
(138)

21.0
(147)

22.0
(153)

Credit:  These tables were extracted the following brochures

Nickel Institute brochure No. 11 021 High Performance Stainless Steels

International Molybdenum Association brochure Practical Guidelines for the Fabrication of Duplex Stainless Steels