JPS59211580A - Anti-corrosion treated material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to anti-corrosion treated materials in high-temperature corrosive environments, particularly 112
4-liter in a high-temperature corrosive environment containing S and CI-ions)
Concerns corrosion-resistant materials such as stainless steel and high alloy materials that exhibit poor corrosion resistance.

In recent years, the environment of newly developed oil fields has become increasingly harsh, and on the other hand, in order to improve the efficiency of coal liquefaction technology, which has recently been desired to be put into practical use, the liquefaction environment has become equally harsh. It has become. In particular, today's oil well environments or coal liquefaction environments contain large amounts of H2S and C1- ions and are at high temperatures, so materials such as oil country tubular goods and reaction vessels used in such environments are susceptible to corrosion. Significant. Moreover, the type of corrosion seen there is
It ranges from general corrosion to localized corrosion such as pitting corrosion and stress corrosion.

Therefore, it is expected that anti-corrosion materials will emerge today that exhibit sloppy 1lli4 corrosion resistance in high-temperature corrosive environments containing H2S and CI- ions, but as mentioned in 1-1, the forms of corrosion are different. Therefore, it is difficult to take uniform measures as a countermeasure, and it is unnecessary to use Cr, Mo, Ni.
Only the use of high alloy materials with high amounts is considered.

However, it takes! , 1-1 is original 1:, l :1
Not only is it expensive in terms of stress, but also problems with workability arise due to the high alloying, and it has not always been satisfactory. Therefore, it has been desired to elucidate the corrosion mechanism under the high-temperature corrosive environment as described in -1- and to develop inexpensive anti-corrosion measures based thereon.

In view of the state of the art in which there was no effective anti-corrosion means other than the use of expensive corrosion-resistant materials, the present inventors continued intensive research and development and arrived at the present invention.

That is, the present inventors have discovered that when a molybdenum sulfide film is formed in a high-temperature H2S-C1- ion-containing environment, general corrosion resistance and pitting corrosion or stress corrosion cracking resistance are significantly improved. completed. In that case, a molybdenum sulfide film exists on the surface,
It was also revealed that corrosion resistance can be further improved by forming a nickel sulfide film as the second layer and a chromium oxide film as the third layer.

Thus, the present invention provides (1) a stainless steel or high alloy material containing 4% or more Ni, on the surface of which a molybdenum sulfide protective coating containing 10% or more MO;
Anti-corrosion treated materials exhibiting corrosion resistance in high temperature corrosive environments containing H2S and CI- ions, and +2)N
Stainless steel or high alloy material containing 4% or more of i, 0.05 μm thick containing 10% or more of metal MO
1-123 and C comprising the above coating layer on the surface
This is an anticorrosion-treated material that exhibits corrosion resistance that deteriorates due to odor in a high-temperature corrosive environment containing I- ions.

In the present invention, the Ni content of the anticorrosive material itself is 4%.
If it is less than that, even if a molybdenum sulfide film is formed on the surface during use in the above environment, the second layer of nickel sulfide film will not be formed, and therefore the third layer will be stable and no chromium oxide film will be formed. Corrosion resistance is not improved. This is because the ultimate corrosion resistance is determined by the stability of the third layer and the presence of the chromium oxide film.

Therefore, in the corrosion protection according to the present invention, 4% or more of nickel is required.

In addition, stainless steel and high alloy materials containing 4% or more of Ni include 5US304.5US3 (14L, 5
US316.5US316L, 5US329J1,
ASUS329LJ2, (S-FR7L/SUS Association Standard, 25Cr-7Ni-3Mo-Cu-W-N)
, 8l1oy 825.18Cr-5Ni-2,7Mo
Packing (8 STM A669.2 phase stainless steel tr4), 2
2Cr-5,5Ni-3M081i (8STM A6
69.2 phase stainless steel), 20Cr-25Ni
-4,5Mo-1,5Cu 6M (8STM
B625, austenitic), A11oy
800, etc., but particularly commonly used ones include 5US304L, 5US316L, 81lo.
y 825, 8l1oy 800, etc. are preferred.

Next, as a means for forming a molybdenum sulfide film in a high-temperature corrosive environment containing H2S-Cl- ions during use, molybdenum ions are added to the high-temperature corrosive solution that forms the use environment. Mo
There are two methods: a method is to provide a coating in which molybdenum sulfide is attached or contained as a metal, and to transform it into a molybdenum sulfide coating in the environment during use.

i) Addition of molybdenum ions: When molybdenum ions are added as Mob,'- ions to a solution in the usage environment, a molybdenum sulfide film is formed on the surface of the material. In that case, preferably M o 042
- Corrosion resistance is improved when 100 ppm or more of -ions are added, but the effect of addition is not significant when the amount is less than 100 ppm. Therefore, in the case of adding molybdenum ions in the present invention, it is preferable to add Mo01'-ions in an amount of IOOppm or more.

11) Formation of metal Mo-containing film: Such a metal Mo-containing film can be easily formed on the surface by ion blasting, plating, thermal spraying, vapor deposition, or the like. In a preferred embodiment of the present invention, the l
It is preferable to form a coating layer containing MIO% or more of metal Mo. This coating layer has a thickness of 0.05. u
By containing the above and MolO% or more, a stable molybdenum sulfide film that significantly contributes to improving corrosion resistance is formed. If the thickness is less than 0.05 μm, local peeling may be observed during sulfide formation during use, and in that case, a sulfide film may not be formed. Also in this case, the metal Mo in the film
Unless it is 10% or more, a homogeneous film of molybdenum sulfide will not be formed.

Next, the present invention will be further explained by examples.

Sharp application week 1 Test materials f4 having the chemical compositions shown in Table 1 were used. Test pieces obtained from these seven steel types (50 Dragon
Corrosion tests for general corrosion, pitting corrosion and stress corrosion cracking were conducted by immersing 20m++x]am) into O-1 to crepe under the following conditions. Test piece for stress corrosion cracking test (75 x
lOryu x 21) is bent into a U shape, and the tip of the drawing is attached with a bolt.
The one fixed with Naso 1~ was used.

Small pox base solution = 5% NaC (! + 10 atm II 2.
5 Temperature: 200°C Time: 250 hr After the test was completed, each test piece was taken out, the overall corrosion rate was determined, and the presence or absence of pitting corrosion and stress corrosion cracking was visually observed. The corrosion test results thus obtained are summarized in Table 2. As is clear from the results shown in Table 2, Ni
For materials with less than 4% Ni content, no effect of MoO4'- ion addition is seen, but for steels containing 4% or more Ni, addition of 100 ppm or more of Na2MoO4 as MoO42- ions improves overall corrosion resistance and This shows that local corrosion resistance is improved in both cases.

IMMA analysis of the cross section of the specimen revealed that a homogeneous molybdenum sulfide film containing 10% or more of MO was formed on the material surface under the conditions of the present invention.

JJ%J Progress I Examples of anti-corrosion treated materials in which a coating layer containing MO was provided by plating on the surface of test pieces obtained from steel numbers No. 2.4 and 6 among the test materials shown in Table 1. A corrosion test using an autoclave similar to 1 was conducted. The results are summarized in Table 3. This effect was not seen in the material with Ni content of less than 4% (steel number N02), but on the other hand,
Materials with Ni content of 4% or more (steel number No. 4.6)
This shows that corrosion resistance is significantly improved when the Mo content of the surface coating layer is 10% or more and the thickness is 0.05 μm or more.

In particular, even in materials that originally contain Mo in their alloy composition,
It should be surprising that corrosion resistance is significantly improved by further providing a coating layer containing MO on the surface according to the present invention. After the corrosion test, the cross-sectional I
MMA analysis revealed that a homogeneous molybdenum sulfide film was formed on the surface in all cases of the present invention.

As described above, the present invention is an inexpensive means for preventing corrosion of relatively low-grade materials in a high-temperature H2S-CF-containing environment, and its excellent corrosion-preventing effect also makes a great contribution to this field.

Claims (1)

[Scope of Claims] (11 Made of stainless steel or high grade steel containing 4% or more Ni and having a molybdenum sulfide protective coating containing 10% or more Mo on the surface, consisting of H2S and CI~
An anti-corrosion treated material that exhibits excellent corrosion resistance in high-temperature corrosive environments containing ions. (2) Stainless steel or high-grade stainless steel containing 4% or more Ni, and 0.0mm thickness containing 10% or more metal Mo.
l-12S with a coating layer of 05μm or more on the surface
and a corrosion-resistant treated material that exhibits excellent corrosion resistance in a high-temperature corrosive environment containing CI- ions.