Corrosion Resistance
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Stress Corrosion Cracking Resistance
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WNS7 is exposed in ammonia vapor and we examined the time of exposure
and the degree of cracking. It is generally said that WNS7 has less stress
corrosion cracking susceptibility. It is superior in stress corrosion cracking
resistance to C2200 (red brass) and a little inferior to C7521 (NS2).
Test method conforms to Materials Research & Standards Feb.1961 108-111.
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Good Corrosion Resistance
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Table 3 Comparison of weight decrease due to corrosion between WNS7 and NS2
which are dipped in various solution 10 days dip at 25oC (unit: mg/dm2/day)
WNS7 has corrosion resistance equivalent to NS2
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Table 3
| Material |
Hydrochloric acid |
Sulfuric acid |
Artificial sweat |
Soy-sauce |
Vinegar |
Detergent |
Gasoline |
| WNS7 |
230 |
79 |
71 |
8 |
152 |
7 |
0.5 |
| C7521 |
570 |
78 |
86 |
9 |
300 |
3 |
0.5 |
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Hydrochloric acid: HCl (1+19) |
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Sulfuric acid:H2SO4 (1+19) |
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Artificial sweat: NaCl 19.9g ＋urea1.7g ＋lactic acid1.7g＋Na2S
0.8g ＋NH4Cl 0.2g/l |
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Soy sauce: Purchased in local market |
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Table 4 color change (color difference value) comparison of WNS7
and NS2 before and after.
WNS7 has discoloration resistance equivalent to NS2 and has better
discoloration resistance than 25 Ni-75Cu and C2801
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Table 4
| Material |
Hydrochloric acid |
Sulfuric acid |
Artificial sweat |
Soy-sauce |
Vinegar |
Detergent |
Gasoline |
| WNS7 |
4.9 |
4.0 |
39.2 |
23.1 |
15.4 |
1.3 |
0.8 |
| C7521 |
3.4 |
5.9 |
43.9 |
28.5 |
11.2 |
0.9 |
0.7 |
Table 5
| Material |
Sweat resistance test |
Salty Spray |
Outdoor Exposure test |
Heating at 150oC |
Heating at 200oC |
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WNS7 |
7.7 |
7.3 |
11.5 |
2.5 |
8.5 |
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C7521 |
7.3 |
10.1 |
13.2 |
4.5 |
8.8 |
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25Ni－75Cu |
10.0 |
18.6 |
12.3 |
11.5 |
40.0 |
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C2801 |
18.5 |
23.5 |
18.5 |
7.5 |
12.0 |
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Sweat resistance test: JIS L0848D |
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Salty Spray test: JIS Z2371, for 72Hr |
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Outdoor Exposure Test: on the rooftop of
our laboratory facing south with 40oC slope for 20 days exposure |
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Heating test: Keeping each temperature in the air for
30 minutes and measuring the value after cooling |
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Other tests: same method as Table 3 |
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