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General Corrosion resistance of 0MO28Ni65Fe5(hastelloyb) alloy —charpter 1

General corrosion
a: Atmosphere
0MO28Ni65Fe5 alloy has good corrosion resistance under all atmospheric conditions (including marine atmosphere and industrial atmosphere), and its corrosion resistance is equivalent to pure bond. Table 7-9 shows the results of experiments in the atmosphere over 12 years and 23 years.

Table 7-9 Results of atmospheric corrosion test of 0MO28Ni65Fe5 alloy

Test condition Test hour/a  Corrosion rate

mm/a

 Pitting maximum depth/mm

mm/a

 Pitting maximum depth/mm
Industrial atmosphere

12

0. 0030

0. 047

0. 0033

0.05
Industrial atmosphere

23

0. 0025

R

0. 0030

R
Marine atmosphere

15

0.0004

0. 125

—

—
Remark： 8-roughness

 

b :aqueous medium
The alloy has excellent corrosion resistance in natural water and high purity water. For example, in natural water such as river water and well water, the corrosion rate is <0.0251^^&; in seawater, when it is at a static or slow flow rate, the alloy has a slightly lower uniform corrosion resistance than pure nickel, and is resistant to pitting and The crevice corrosion performance is better than pure nickel.
c : acidic medium
In a reducing acidic medium, the alloy has good corrosion resistance, and the presence of an oxidizing agent accelerates the corrosion of the alloy.
(1)  In H2S04.
Ni-Mo corrosion-resistant alloys have excellent corrosion resistance in air-free and non-oxidizing sulfuric acid, and the applicable concentration and temperature range are quite wide. For example, in all concentrations of H2S04 below 100 degrees, the corrosion rate of Hastelloy B alloy is less than 0.125 mm/a; in any concentration of H2S04 below 115 degrees, <5 mm/a; in H2S04 below boiling temperature, Hastelloy B alloy The concentration of H2S04 corrosion resistance can reach 60%; the concentration is higher, due to the high oxidation of H2S04 itself, Hastelloy B alloy is subject to severe corrosion; in dilute H2S04, the corrosion resistance of Hastelloy B alloy increases with the amount of air enriched. It is reduced, and it is most obvious when the concentration of H2S04 is 5%~10%. Figures 7-15 and 7-10 are some of the test results.
Table 7-10 Corrosion resistance of hastelloyB alloy in H2S04

H2S04  concentration/%

 Corrosion Rate/mm.a~1

室温

65度

沸腾
2

0. 0254

0. 1270

0.0254
5

0. 0254

0. 1026

0. 0254
10

0. 0254

0.0762

0. 0508
25

0. 0254

0. 0254

0. 0508
50

0.0102

0. 0254

0. 0508
60

0.0051

0. 0254

0. 1778
77

0. 0051

0. 0102

>25.8
80

0. 0025

0. 0076
85

0. 0025

0. 0076
90

0. 0025

0. 0076

—
96

0. 0051

0. 0076

—
50% H2S04 +Nitrate and traceFe3+,Ca2‘ ,Pb2 +

—

—

0.418
In the process of producing alcohol, it is also often encountered in a concentration of 45% to 65%, and the temperature is 115 to 120 degrees than H2S04. Other materials, such as stainless steel, nickel-based or copper-based alloys, can be ≤0.5 mm/a at rest and low flow rates. However, at high flow rates and high temperatures, the corrosion rate should exceed 2.5 mm/a. However, the results of the Hastelloy B alloy at 45% to 65% H2S04, 115 ° factory test conditions show that the corrosion rate is only 1 mm / a.
Sulfuric acid is also often used in the refining of petroleum products to remove resin, asphalt or gum-like materials. The corrosion resistance of Hastelloy B alloy under these conditions is also very good, see Table 7-11. Parts such as pumps and valves cast from 0Mo28Ni65Fe5 alloy are suitable.
The addition of oxidizing salts (nitrate, chromate, permanganate, etc.) and other oxidizing ions Fe3+, Ca2+, etc. to H2S04 can significantly improve the corrosion rate of hastelloy B alloy, and the higher the temperature, the more serious. Therefore, hastelloy B alloys are generally not allowed to be used under these conditions unless the concentration of oxidizing salts and oxidizing ions is low enough to affect the corrosion resistance of the 0hastelloy B alloy. Table 7-12 shows the effect of Cu in H2S04 on the corrosion resistance of 0M028Ni65Fe5 alloy. Obviously, in the case of H2S04 containing Cu or the possibility that Cu may enter H2S04, it is not suitable to use 0M028Ni65Fe5 alloy. In addition, the contact of Hastelloy B alloy with carbon, graphite, etc. will also cause rapid damage due to galvanic corrosion. Table 7-13 shows the test results. Since graphite is also a non-metallic material with good sulfuric acid resistance, when 0Mo28Ni65Fe5 alloy is used together with graphite, care should be taken to prevent such galvanic corrosion.
 Table 7-12 Effect of Cu content in H2S04 on corrosion resistance of alloy

Medium

 Corrosion Rate/mm.a~1

45%  H2S04,115，test for 6.5 days,static

 0. 230

45%  H2S04,+1.54g/L Cu

 1. 170

45%  H2S04,+ 0.6% Cu

 3.660
Table 7-13 Galvanic corrosion of graphite and 0Mo28Ni65Fe5 alloy

Test condition

                      Corrosion rate /mm.a~1

casting alloy

Deformed alloy

a galvanic couple with graphite

0. 150

0. 100

Coupled with graphite

13.275

12.675
(2) In HCI.
In the hydrochloric acid which is not filled with air, the 0Mo28Ni65Fe5 (Hastelloyb) alloy is corrosion-resistant at any concentration and at any temperature under normal pressure. Ni-Mo corrosion resistant alloys, including 0Mo28Ni65Fe5 (Hastelloyb) alloys, are among the best resistant to hydrochloric acid. As a corrosion-resistant metal material, only the metals Mo, Zr, W, and Ta have higher corrosion resistance than Ni-Mo corrosion-resistant alloys.

Figure 7-16 and Table 7-14 show the results of 0Mo28Ni65Fe5 (Hastelloyb) alloy in hydrochloric acid. It can be seen from these results that the corrosion resistance of 0Mo28Ni65Fe5 (Hastelloyb) alloy is greatly affected by the presence or absence of air in hydrochloric acid; when there is air in the acid, the adverse effect on the corrosion resistance of OM028Ni65Fe5 alloy is 5 The most obvious when %~ 10%. Tables 7-15 show the test results when nitrogen is charged and charged (oxygen + nitrogen) in the gas phase. The adverse effects of oxygen can also be seen. Hydrochloric acid is produced during the treatment of certain organic and inorganic aqueous chlorides. Under some chlorinated carbon hydride conditions, condensation of hot vapor can produce a higher concentration of hydrochloric acid.

Table 7-14 Corrosion resistance of 0Mo28Ni65Fe5 alloy in various concentrations of hydrochloric acid

HCI consentration/%

corrosion rate/mm.a~1

room temperature

65 deg

             boil

1

0. 0762

0. 2286

0. 0508

2

0. 0508

0. 2286

0. 0762

5

0. 0508

0. 2286

0. 1776

10

0. 0508

0. 1778

0. 2286

15

0. 0254

0. 1524

0. 3556

20

0. 0508

0. 1270

0. 6096

25

0. 0254

0. 1026

一

37

0.⑻了巴

0. 0508

—
Table 7-15 Corrosion resistance of hastelloyB alloy in hydrochloric acid (pressure 14 MPa)

HCI concentration/%

temperature deg

               corrosion rate/mm.a~1

In nitrogen

 in 20%02 + 80%N2 gas

10

70

—

2. 125

10

100

0.200

6. 550

10

135

0. 500

10. 050

25

70

0. 050

1.450

25

100

0.200

3. 875

25

135

1.225

8. 400

37

70

0.050

0. 175

37

100

0.300

2. 030

37

135

2. 200

7. 375
(3) HF acid.
Limited testing in hydrofluoric acid has shown that hastelloy B alloy is resistant to aging at 100 ° C, air-free HF acid. However, the hastelloy B alloy is corroded in hydrofluoric acid having a constant boiling point concentration of 38% to 40% and a boiling temperature of 115 ° C. The results are shown in Table 7-17. An HF acid higher than a constant boiling point concentration can be obtained by dissolving anhydrous HF in water. For HF acids with a concentration of ≥70%, the corrosion resistance of hastelloyB alloy is better than that of lower concentration HF acid. The corrosion of hastelloy B alloy under HF acid regeneration conditions is shown in Table 7-18. Obviously, this alloy has good corrosion resistance.
Table 7-17 Corrosion resistance of hastelloy B alloy in hydrofluoric acid

HF concentration/%

temperatrue

test time/h

other condition

corrosion rate/mm.a~1

5

room

24

0. 100

Liquid phase

0. 100

8

room

2880

Etching glass solution

In the spray box

0. 150

Gas phase

0. 275

25

room

24

0. 125

40

55

—

0. 0225

38

110

48

Sample 2/3 is immersed, graphite container, filled with some air

1.625

45

room

24

0.075

45

102

1176

Adding isobutane vapor

0. 070

50

60

100

Add 50% H2S04, fill the air

1.550

50

176

167

Add 7% H2S04, and

1% H2SiF6

0. 800

60

room

—

0. 400

60

32

672

Add 1.3% H2S044 and trace H2SiF6

0. 0050

98

38

87

Sample 2/3 immersed, graphite container, filled with some air

0.103

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Post time: May-14-2019