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Hastelloy B-2, NS 3202 chemical composition,organizational structure and mechanical properties

Hastelloy B-2, NS 3202 chemical composition,organizational structure and mechanical properties

Chemical composition and organizational structure
The chemical composition of Hastelloy B-2 alloy is shown in Table 7-6. This alloy was developed to prevent intergranular corrosion and knife edge corrosion of Hastelloy B-2 alloy. The main difference between it and Hastelloy B-2 alloy is the change of chemical composition, the carbon content in the alloy is reduced to <0.02%, the silicon content w(Si) is reduced to 0. 10%, the iron content is w; ) dropped to <2% and V was removed. This chemical composition change has no effect on the microstructure of the solid solution state, but it improves the thermal stability of the alloy structure, and significantly reduces the precipitation phase of the intermetallic phase and carbide of the sensitized alloy. Resistance to intergranular corrosion. The alloy has aging brittleness. It was later confirmed that the disadvantage is caused by the fact that the Fe is reduced to a mass fraction of less than 2%, and the alloy is likely to precipitate phase B. The precipitation of phase B not only causes the plasticity toughness of the aged alloy to decrease, but also In order to eliminate or suppress this poor performance, a new generation of alloys controlling Fe + Cr content has been developed.

Room temperature mechanical properties
The room temperature mechanical properties of Hastelloy B-2 alloy are shown in Table 7-29. The effect of aging on alloy plasticity is shown in Table 7-30. The plasticity is reduced by aging at 700 ~ 800 °C, and the most sensitive at 760 °C.

Table 7-29 Mechanical properties at room temperature and medium temperature of 00Mo28Ni68Fe2 alloy

type

Inspection status

temperature

Rm/MPa

Rp0.2/MPa

A/%

Hardness

sheet

1.3 ~3.1 mm

1066°C   After heating

Quenching

room temperature

955

526

53

22HRC

204

885

451

50

316

864

426

49

427

866

418

51

plate

2. 5〜8. 9mm

1066°C   After heating

Quenching

room temperature

894

412

61

95 HB

204

849

350

59

316

823

328

60

427

806

310

60

plate

9. 1 〜51 mm

1066°C   After heating

Quenching

room temperature

902

407

61

94 HB

204

871

361

60

316

840

336

60

427

823

319

61

plate 6. 4mm

Manual TIG welding

Semi-automatic TIG welding

room temperature

855

room temperature

821

Manual TIG welding +

1066 ° C solid solution

room temperature

817

Semi-automatic TIG welding +

1066 ° C solid solution

room temperature

796

plate 12. 7mm

Manual TIG welding

room temperature

897

Table 7-30 Plasticity after aging of 00Mo28Ni68Fe2 alloy sheet

Aging temperature/h

Aging time/h

A/%

Aging temperature/°C

Aging time/h

A/%

 

1

48

 

1

48

704

5

39

732

5

14

10

27

10

17

   
 

30

13

 

30

7

 

1

44

 

1

45

760

5

14

788

5

14

10

3

10

4

 

30

2

 

30

3

Corrosion resistance
The overall corrosion resistance of this alloy is basically the same as that of 0Mo28Ni65Fe5 alloy in various media. In comparison, the performance of Hastelloy B-2 alloy is better. Some corrosion test data are shown in Table 7-31 ~ Table 7-33 and Figure 7-24 ~ Figure 7-33. Among the non-oxidizing inorganic acids, the alloy exhibits excellent corrosion resistance, and even if it is cold-processed and reaches 50%, the corrosion resistance of the alloy is not impaired.

Table 7-31 Corrosion resistance of Hastelloy B-2 alloy in boiling temperature 20% HCl acid

condition

corrosion rate

hardness HRC

mil/a

mm/a

Solution treatment state

14

0.36

82HRB

Cold working deformation 10%

14

0.36

32

Cold working deformation 20%

14

0. 36

38

Cold working deformation 30%

13

0.33

43

Cold working deformation 40%

14

0. 36

44

Cold working deformation 50%

14

0.36

45

Table 7-32 Comparison of Corrosion Resistance of Hastelloy B-2 Alloy and 0Mo28Ni65Fe5 Alloy in Boiling 20% HCl Acid

alloy

corrosion rate/mm . a -1

Solution treatment state

Welded state

00Mo28Ni68Fe2

0.38

0.51

0Mo28Ni65Fe5

0.71

>1.49

Table 7-33 Corrosion resistance of Hastelloy B-2 alloy in boiling acid medium

Medium

acid concentration/%

corrosion rate /mm – a-1

hydrochloric acid

1

0. 02

2

0. 08

5

0. 13

10

0. 18

15

0. 28

20

0. 38

20

0.51 (TIC welded state)

phosphoric acid

10

0.05

30

0.08

50

0. 15

85

0. 63

 

2

<0.02

5

0.08

10

0. 05

20

<0.02

30

<0.02

40

<0.03

            sulfuric acid

50

0.03

 

50

0.05 (TIG welded state)

 

50

0. 03

60

0.05

70

0. 23

acetic acid

10

<0. 02

30

0.01

50

0.01

70

<0.01

99(glacial acetic acid)

<0.01

 formic acid

10

<0.01

20

<0.02

30

<0.02

40

<0.02

60

<0. 02

89

<0. 02

Note: The sample is solution treated at 1066 ° C and tested under the actual conditions of the factory.

B intergranular corrosion
Hastelloy B-2 alloy has better resistance to intergranular corrosion (including knife edge corrosion) than Hastelloy B-3. The TTS data is shown in Table 7-3.
C stress corrosion
The aged state Hastelloy B-2 alloy is sensitive to scc in H2S04 acid and high temperature hydrogen chloride gas. The stress corrosion behavior in boiling 10% H2S04 and in HI is shown in Table 7-4 and Table 7-34, respectively.

Hot working, cold working, heat treatment and welding performance
(1) Hot working and cold working. The hot and cold workability of this alloy is the same as that of Hastelloy B-2 alloy.
(2) Heat treatment. The alloy is used in a solution treatment state, the solution treatment temperature is 1066 ° C, and is quickly cooled after being kept warm, the thick section material is water-cooled, and the thin section material can be rapidly air-cooled. 538~816 °C for this alloy’s low plastic zone, it is not suitable to stay in this temperature range for a long time, it is not suitable to use in this temperature range.
(3) Welding. This alloy has good welding performance and the welding method is the same as that of 0Mo28Ni65Fe5 alloy. Due to the low carbon and low silicon content of the alloy, its resistance to intergranular corrosion and knife edge corrosion after soldering is better than that of Hastelloy B-2 alloy, and it does not need to be solution treated after welding.

Table 7-34 SCC1 of Hastelloy B-2 alloy in 1 %
type of alloy Breaking time/h
177¾ 204°C 232°C
00Mo28Ni69Fe2 (B-2) 168、 168、 366② 48、 168、 168② 48、 48、 48②
Ni200 Uncleaved Uncleaved Uncleaved

Ni68Cu28Fe( Monel 400)

Uncleaved Uncleaved Uncleaved

0Crl5Ni75Fe( Inconel 600)

Uncleaved Uncleaved Uncleaved

1 Annealed state, two-point bending specimen, 1000h test.
2 Transgranular fracture.

Application
The application field of this alloy is the same as that of Lai Hastelloy B-2 alloy. It is mainly used for pipes, vessels and their linings, pumps and valve parts resistant to hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, etc. For the selection of welded parts and equipment, and can not be applied to the solution treatment, this alloy should be used instead of Hastelloy B-2 alloy.

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Post time: May-22-2019