8. 3. 1.3 Corrosion resistance
a ：seawater
0Crl6Ni60MO16W4 alloy in the seawater, after 10 years of test results show that its corrosion rate ≤ 0. 025mm / a, and no pitting corrosion. b sulfuric acid
In sulfuric acid, the alloy has good corrosion resistance in various concentrations of H2SO4 at room temperature, and its corrosion rate is < 025 mm/a, and the air is not affected by the corrosion resistance. Figure 8-15 shows the test results of 0Crl6Ni60Mol6W4 alloy in H2S04. The alloy has good corrosion resistance in any concentration of H2S04 below 70T. The corrosion resistance of the alloy in fuming sulfuric acid is shown in Table 8-9.
Table 8-9 Corrosion resistance of Hastelloy C, NS 3303 alloy in fuming H2S04
|
medium |
corrosion rate/mm • a_l |
|||
|
room temperature |
170-310¾ |
Boiling temperature |
||
|
99%H2S04 |
Liquid phase |
0.013 |
0.725 |
2. 025 |
|
Gas phase |
— |
— |
5.80 |
|
|
75%H2S04 + 25%S03 |
Liquid phase |
0.0075 |
0. 650 |
1.80 |
|
Gas phase |
— |
— |
1.25 |
|
c ：hydrochloric acid
In hydrochloric acid, the corrosion resistance of Hastelloy C, NS 3303 alloy is not as good as Ni-Mo alloy, but the corrosion rate is less than 0.5mm/a in various concentrations of room temperature hydrochloric acid. When the hydrochloric acid is filled with air, it is only above room temperature. The corrosion resistance is only slightly reduced. 0Crl6Ni60Mol6W4 alloy is much less sensitive to oxygen in the medium than Ni-Mo alloy. When the acid is FeCl3, CuCl2 and other oxidizing salts, the uniform corrosion resistance of the alloy is slightly reduced. Some tests are shown in Figures 8-16 and 8-10. This alloy is corrosion resistant in <37% HC1 acid below 50 °C.
Table 8-10 Corrosion resistance of 0Crl6Ni60Mol6W4 /hastelloy C alloy in hydrochloric acid under different atmospheres
|
corrosion rate/mm – a-1 |
|||
|
HCl Acid concentration /% |
temperature/℃ |
Under the N2 gas |
nder 20% 02 + 80% N2 atmosphere |
|
10 |
70 |
— |
2. 85 |
|
10 |
100 |
5.700 |
7.32 |
|
10 |
135 |
— |
725.00 |
|
25 |
70 |
1.00 |
2.275 |
|
25 |
100 |
15.30 |
11.225 |
|
25 |
135 |
一 |
725.00 |
|
37 |
70 |
1.575 |
4.62 |
|
37 |
100 |
725. 00 |
3.47 |
|
37 |
135 |
— |
9.72 |
Note: Sealed in a glass tube and tested for 24h.
d ：hydrofluoric acid
0Crl6Ni60Mol6W4 alloy in HF acid, its corrosion resistance decreases with increasing temperature. The HF acid has a constant boiling point concentration of about 36% and a boiling point of 112 °C. Higher concentrations of HF acid can only be obtained by dissolving anhydrous HF in water. Table 8-11 shows the test results of 0Cr16Ni60Mol6W4 alloy at different concentrations, temperatures and different test conditions. In room temperature HF acid, the corrosion rate of this alloy does not exceed 0.25 mm / a, and the corrosion rate of the air-filled 0Crl6Ni60Mol6W4 alloy increases with the increase of temperature.
Table 8-11 Corrosion resistance of Hastelloy C, NS 3303 alloy in HF acid
|
HF Acid concentration /% |
temperature/℃ |
test hour/d |
corrosion rate /mm • a ~1 |
Other test conditions |
|
5 |
room temperature |
1 |
0.025 |
|
|
25 |
room temperature |
1 |
0. 125 |
|
|
45 |
room temperature |
1 |
0. 150 |
|
|
40 |
room temperature |
— |
0. 75 |
The sample invades the open container |
|
40 |
55 |
0.250 |
||
|
38 |
110 |
2 |
1.975 |
The sample invades the open container |
|
50 |
60 |
35 |
0.725(Liquid phase）0.600(gas phase） | Samples • Invaded and sealed graphite containers, some of which are filled with nitrogen in the air. |
|
50 |
boiling |
4 |
1.675(Liquid phase) 4. 100(gas phase） |
Purification with 99% N2 in the gas phase |
|
60 |
room temperature |
— |
0.090 |
The sample invades the open container |
|
60 |
boiling |
4 |
0.425(Liquid phase） 0. 375(gas phase) |
Nitrogen in the gas phase |
|
65 |
60 |
35 |
0.190(Liquid phase) 0.240(gas phase) | |
|
98 |
38 |
0.025 |
The sample invaded the closed graphite container and there was some air. |
e phosphoric acid
The corrosive nature of phosphoric acid is closely related to the preparation of phosphoric acid, specifically to the impurities of phosphoric acid. Generally, wet-process phosphoric acid is more corrosive than pyrophoric acid because wet-process phosphoric acid contains free F-, Cl- ions and SO2/4. This alloy has good corrosion resistance except for high temperature H3PO4. Under the conditions of 55% H3 PO4 + 0.8% HF acid at boiling temperature,
The corrosion rate of 0Crl6Ni60Mol6W4 alloy does not exceed 0.75 mm/a. In wet-process phosphoric acid, this alloy has excellent corrosion resistance (Table 8-13).
Table 8-12 Corrosion resistance of Hastelloy C, NS 3303 alloy in H3P04
|
10%® |
30%® |
50%® |
75%® |
85%® |
||||||
|
190°0 |
78^: |
85*C |
90*0 |
95 V |
105*€ |
55^ |
100^ |
1601： |
||
|
1.00 |
3.50 |
7.50 |
0. 0225 |
0. 0300 |
0.0325 |
0.055 |
1. 150 |
<0.0025 |
0.0425 |
1. 125 |
1 In reagent type H3PO4.
2 in wet method H3PO4.
3 In pure H3P04.
Table 8-13 Corrosion test results of Hastelloy C, NS 3303 alloy in F-containing H3P04 and wet method H3PO4
| Medium |
corrosion rate/mm. |
|
55%H3P04+0.8%HF acid，boiling temperature |
0.725 |
|
Evaporator in the liquid phase： 53%H3P04+1% ~2%H2S04+1.5%Fluoride，120¾ |
0.0125 |
|
Evaporator in the liquid phase： 36% H3P04 + 2.9% H2S04 + 350 x 10 _6C1 – + Small amount of HF acid, 76 -84X |
0. 120 |
|
In the evaporator： 55%H3P04+A small amount of H2SiF6+ other fluorides，79-85T |
0.0675 |
|
39%H3P04 +2%H2S04 + a small amount H2Si+fflHF acid, 76-85¾ |
0. 0825 |
f nitric acid
The corrosion resistance of Hastelloy C, NS 3303alloy in nitric acid is shown in Figure 8-18. This alloy has suitable corrosion resistance in all concentrations of room temperature nitric acid or low concentration high temperature nitric acid. However, the price of the alloy is more expensive than that of stainless steel, and it is generally not suitable, unless it is necessary to solve the corrosion problem that stainless steel cannot solve at the same time.
g mixed acid containing HNO3
H3PO4 + HF acid mixed acid is a solution commonly used in metallurgical pickling process and nuclear fuel post-treatment process. With the increase of NHO3 concentration in the medium and the increase of temperature, the corrosion rate of the alloy increases, and the corrosion rate of the alloy is too high. Poor sex, see Table 8-14. The corrosion test results in HNO3 + HC1 mixed acid are shown in Table 8-15. This medium is extremely corrosive, although the alloy has good corrosion resistance in room temperature aqua regia (HCI: HNO3 = 3:1), but at high temperature. There is no satisfactory corrosion resistance in the media.
Table 8-14 Corrosion resistance of Hastelloy C, NS 3303 alloy in HN03 + HF acid mixed acid
|
test condition |
corrosion rate/mm – a-1 |
|
|
8%HNO3 +2%HF,room temperature，Pickling tank，45h |
0. 350 |
|
|
15%HNO3 +2%HF, 30 -57℃,Pickling tank，4天 |
3.075 |
|
|
15% ~20%HNO3 +2% ~3%HF, 10 -23℃, 43h |
12. 275 |
|
|
15%HNO3 +3%HF,Under boiling conditions，48h |
11.70 |
|
|
39% HNO3 +3.5%HF |
63℃, |
82.20 |
|
81℃, |
345. 00 |
|
|
50%HNO3 +14%HF, 10-32℃, 72h |
27.50 |
|
Table 8-15 Corrosion resistance of 0Crl6Ni60Mol6W4 alloy in HN03 + HC1 mixed acid
| Medium |
temperature/t |
corrosion rate/mm – a”1 |
|
13.3%HN03 +11. 8% HCI |
71 |
1. 125 |
|
13.5%HN03 +11. 8% HCI |
88 |
12.6 |
|
17. 25% HN03 +15. 2% HCI |
71 |
12.9 |
|
17.2%HN03 +15. 2% HCI |
88 |
>25.0 |
h :chromic acid
Chromic acid is a strong oxidizing acid, but its ionization tendency is not large, so 0Crl6Ni60Mo 6W4 alloy has excellent corrosion resistance in any concentration of chromic acid at moderate temperature (Table 8-16).
i : organic acids and mixtures thereof
Table 8-17 to Table 8-22 show the corrosion resistance of 0Crl6Ni60Mol6W4 alloy in organic acids such as formic acid and acetic acid and their mixtures. These data show that the alloy has very good or better resistance under different test conditions. Corrosive.
Table 8-16 Corrosion resistance of Hastelloy C, NS 3303 alloy in chromic acid
|
acid concentration（CrO2) /% |
temperature/℃ |
corrosion rate /mm • a’1 |
acid concentration（CrO2) /% |
temperature | corrosion rate/mm • a•1 |
| 2 | room temperature | none | 10 | boiling | 0. 425 |
| 2 | 66 | none | 20 | room temperature | 0.0025 |
| 2 | boiling | 0. 050 | 20 | 66 | 0. 125 |
| 10 | room temperature | none | 20 | boiling | 1.45 |
| 10 | 66 | 0. 050 |
Table 8-17 Corrosion resistance of 0Crl6Ni60Mol6W4 alloy in boiling formic acid
| corrosion rate/mm • a”1 | |||||
|
0Crl6Ni60Mol6\V4 |
0Cr22Ni46Mo7Fe20 |
0Crl8Nil2Mo2 | |||
| 10%,Unfilled air |
liquid phase |
— | — | 0.025〜0.475 | |
| 50%,Unfilled air |
liquid phase |
— | — | 0.025 – 0. 05 | |
|
gas phase |
— | — | 0.750 | ||
| 50%,filled air |
liquid phase |
0. 125 | 0.025 | 0.025 | |
|
gas phase |
0.050 | 0. 300 | 0.025 -1.425 | ||
| 90%,Unfilled air |
liquid phase |
0.050 | 0. 025 -0. 300 | 0.025 -1.375 | |
|
gas phase |
— | 0.225 | 0. 125 | ||
| 90%,filled air |
liquid phase |
0. 175 | 0. 850 | 0.025 | |
|
gas phase |
0.025 | 0. 300 | 1.00 | ||
Table 8-18 Corrosion resistance of 0Crl6Ni60Mol6W4 alloy in unfilled acetic acid
| acid concentration/% |
temperature/V |
corrosion rate/mm – a’1 |
acid concentration/% |
temperature/°c |
corrosion rate/mm – a’* |
| 10 | room temperature | 0. 005 | 50 | boiling | 0.0025 |
| 10 | 65 | 0.005 | 99 |
room temperature |
0.005 |
| 10 | boiling | 0.010 | 99 |
65 |
0. 0025 |
| 50 | room temperature | 0. 0025 | 99 |
boiling |
0.0025 |
| 50 | 65 | 0. 0025 |
Table 8-19 Corrosion resistance of 0Crl6Ni60Mol6W4 alloys in boiling organic acids and some mixtures
| corrosion medium | corrosion rate/mm • a_l | ||
|
0Crl6Ni60Mol6W4 |
lCr22Ni60Mo9Nb4AlTi |
0Cr7Ni70Mol6 | |
| glacial acetic acid | 0. 0225 | <0.025 | <0. 100 |
| Glacial acetic acid mixed with acetic acid1 : 1 | 0.250 | 0.050 | 1.062 |
| 10% acetic acid + 10% formic acid | 0.050 | <0.025 | <0.025 |
| 5% formic acid | 0.075 | 0.025 | 0. 200 |
| Hexanoic acid (C5H, COOH) mixture (75% hexanoic acid + 11% butanol + 10% acetic acid + 0.3% H2S04 + 4% water) | 0. 275 | 8. 35 | |
able 8-20 Corrosion resistance of 0Crl6Ni60Mol6W4 alloy in acetic acid-containing mixture under factory conditions
|
corrosion medium |
temperature/℃ |
test time /d |
corrosion rate /mm • a*1 |
|
80% acetic acid + 2% – 3% formic acid + 3.5% propionic acid + small amount of H20, in a distillation tank |
90 |
1126 |
0. 100 |
|
20% acetic acid + 50% acetaldehyde + H20 in the distillation tank |
100 |
112 |
0.0175 |
|
86%-91% acetic acid, 8.5% salicylic acid in the gas phase of the distillation tank |
127 |
37 |
0. 0020 |
|
75% acetic acid + 20% commercial boiling compound + 5% H2O in a distillation tank |
126 |
216 |
0.0075 |
|
58% acetic acid + 28% propionic acid + 75% isobutyric acid + 7. 5% n-butyric acid |
130 |
21 |
0. 200 |
Table 8-21 Corrosion resistance of 0Cr16Ni60Mol6W4 alloy in other organic acids and mixtures
|
medium |
temperature/℃ |
test time /d |
corrosion rate /mm • a |
|
66% propionic acid + 17% isobutyric acid + 17% n-butyric acid in a still |
150 |
21 |
0.0075 |
|
28%~58% crude lime acid, in a vacuum concentrator |
54 |
5 |
0. 1125 |
|
30%~60% lactic acid in a vacuum concentrator |
46 |
42 |
0. 0007 |
|
a mixture of valeric anhydride and (CHC0)2O in a distillation tank |
204 -285 |
45 |
0.0025 |
|
20% formaldehyde + 10% ~ 15% a drunk + 0.1% formic acid in a distillation tank |
135 |
71 |
<0. 050 |
Table 8-22 Corrosion resistance of 0Crl6Ni60Mol6W4 alloy in chloroacetic acid (C1CH2C02H)
|
corrosion medium |
temperatur |
test time/d |
corrosion rate/mm • a *1 |
|
100% molten chloroacetic acid |
70 |
2.7 |
0. 0075 |
|
100% molten chloroacetic acid |
170 |
23. 8 |
0. 355 |
|
78% gas acetic acid + 22% H2O |
10 ~20 |
28 |
0. 0025 |
|
78% gas acetic acid + 22% H2O |
50-60 |
17 |
0.075 |
|
90% acetic acid + 10% H2O |
24 |
4. 1 |
0. 0025 |
|
70% grade acetic acid + 25% four gasified carbon + 5% barium acid |
40-50 |
14.2 |
0. 0075 |
|
60% grade acetic acid + 1.5% acetyl acid + 5% hydrochloric acid + acetic acid |
60 |
— |
0. 50 |
j halogen gas
0Cr16Ni60Mol6W4 alloy is resistant to corrosion by dry chlorine, bromine and iodine except fluorine. When there is moisture, it will accelerate the corrosion of the alloy. For example, it can only be used in the environment of temperature: 4040 ° in wet chlorine. Some test data are shown in Table 8. -23 and Tables 8-24, it can be seen that under most conditions, Ni-Cr-Mo alloy has excellent corrosion resistance, and corrosion resistance to dry and wet chlorine is one of high Mo content Ni-Cr-Mo-W alloy. Important features.
Table 8-23 Corrosion resistance of 0Crl6Ni60Mol6W4 alloy and 0Crl8Ni60Mol7 alloy in moisture
|
corrosion media |
temperature/V | test hour/d | 0Crl6Ni60Mol6W4
(Deformed material） |
0Crl8iNi60Mol7 (casting） |
|
Dry oxygen |
-18 |
139 |
0.000025 |
0.000150 |
|
Dry gas |
60 |
36 |
0. 0050 |
0.0025 |
|
Moist gas |
10 |
139 |
0.0017 |
0.0125 |
|
Wet suffocation |
16 |
73 |
0.0017 |
0.0100 |
|
Moist gas |
38 |
133 |
0. 0025 |
0.0150 |
|
Wet suffocation |
77 |
67 |
0.0200 |
0.275 |
|
Wet suffocation |
88 |
202 |
0. 125 |
1.350 |
|
Gas with saturated water |
88 |
2 |
2. 700 |
— |
|
Wet gas |
96 |
99 |
0.025 |
0. 300 |
|
Wet chlorine containing condensed water and organic matter |
77 |
67 |
0.0175 |
0. 200 |
|
Moisture with misty brine |
40 |
300 |
0.325 |
0.0625 |
|
Moisture with misty brine |
88 |
74 |
0. 125 |
0.0750 |
|
Moisture with misty brine |
88 |
28 |
5.25 |
3.725 |
Table 8-24 Corrosion resistance of Ni-Cr-Mo alloy in aqueous solution containing
|
腐蚀介质 |
温度/℃ | 试验时间/d |
腐蚀速度/mm – a’* |
|
| 0Crl6Ni60Mol6W4
(变形材） |
0Crl8Ni60Mol7 (铸件） |
|||
|
Distilled water containing saturated Cl2 |
30 |
2.8 |
0.0273 |
— |
|
Distilled water containing saturated Cl2 |
88 |
3.0 |
0. 1125 |
— |
|
Fresh water containing saturated Cl2 |
96 |
166 |
0.0475 |
0. 2075 |
|
River water with saturated Cl2 |
93 |
14 |
0.0750 |
0.350 |
|
Seawater containing saturated Cl2 |
95 |
63 |
0. 0750 |
0.670 |
|
20% NaCl solution containing saturated Cl2 |
88 |
28 |
1. 100 |
3.900 |
|
20% NaCl solution containing saturated Cl2 |
93 |
204 |
0. 625 |
2.415 |
k HF gas
0Crl6Ni60Mol6W4 alloy has excellent corrosion resistance to high temperature HF gas and can be used in <750T: HF gas. Its corrosion resistance is not sensitive to the presence of oxygen. Some test results are shown in Figure 8-9 and Figure 8-20.
Send your message to us:
Post time: May-30-2019