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Super-austenitic stainless steel

A super austenitic stainless steel technology, applied in the field of super austenitic stainless steel, can solve the problems of structural difficulties, deterioration of structural stability, deterioration of corrosion resistance and other problems

Inactive Publication Date: 2005-03-02
SANDVIK INTELLECTUAL PROPERTY AB
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Known alloyed austenitic steel grades, such as the alloys described in SE465373 incorporated herein by reference, or nickel-based alloys such as Alloy 59 have the disadvantage that structural stability can only be maintained within a very narrow temperature range, which means that manufacturing Huge structures are difficult and subsequent processing such as welding is more complicated
Deterioration of structural stability leads to deterioration of corrosion resistance and shortens the service life of products made of these alloys in the above environments

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0093] The general corrosion resistance was tested by exposing the steel of the present invention to the following environment:

[0094] - 1.5% HCl at boiling temperature,

[0095] 30% H at -80°C 2 SO 4 ,

[0096] 50%H at -90°C 2 SO 4 ,

[0097] -25% formic acid + 50% acetic acid and 2000ppm Cl - mixture,

[0098] Mixed with 41.9% P at -90°C 2 o 5 +1.8%F - 43% H 3 PO 4 .

[0099]In each case, two tests were performed on each test material. The test was carried out according to the following procedure: Exposure for three periods of 1+3+3 days, activation with Zn strips at the beginning of each period. The results for each sample use the average corrosion rate tested in time periods 2 and 3. The test results are summarized as follows:

[0100] Corrosion rate (mm / year)

[0101] 1.5% HCl at boiling temperature 1-2.5

[0102] 30%H at 80°C 2 SO 4 0

[0103] 50%H at 90°C 2 SO 4 ...

Embodiment 2

[0110] In the processing, refining and oil and gas industries, treated or untreated seawater is commonly used to cool various reagents. In the usual construction, tubular heat exchangers are used with welded tubes or tubes introduced into a tube sheet. A common form of tubular heat exchangers is that the tubes are bent into a U-shape and both the outlet and inlet are made of the same herringbone tube. In the manufacture of U-shaped tubes, the bends are cold worked so that stress relief annealing can be performed. Seawater is used to cool the tubular section, therefore, good corrosion resistance to chloride-containing environments, especially seawater, is required. Seawater corrosion is characterized by chlorides causing localized corrosion. Standard method ASTM G48A was used to measure localized corrosion in seawater, ie seawater considered to simulate chlorination, which is the most severe case of seawater corrosion. It has been determined that cold working reduces resista...

Embodiment 3

[0113] In order to find the appropriate heat treatment temperature, an annealing test of 8 heat no. materials was carried out within 1 hour at different temperatures. The results in Table 2 are summarized after the study of the microstructure:

[0114] Heat no.

1050

1075

1100

1125

1150

1175

1200

1225

1250

1

-

-

-

-

-

○

○

○

○

2

-

○

○

○

○

-

-

-

-

3

-

-

-

×

×

○

○

○

○

4

-

-

×

×

○

○

-

-

-

5

○

○

○

○

○

-

-

-

-

6

-

-

-

-

-

×

×

×

○

[0115] ○-No precipitation

[0116] "-" - not tested

[0117] x-trace

[0118] X-ph...

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Abstract

Use of a super-austenitic stainless steel alloy with a composition, balanced in such a way that the alloy and products made from the alloy fulfil high requirements on a combination of high corrosion resistance, especially in inorganic and organic acids and mixtures thereof, good general corrosion resistance, good structure stability as well as improved mechanical properties in combination with good workability, in particular in the embodiment tubes, especially seamless tubes and seam welded tubes for application in said environments and with following composition, in weight-percent: Cr 24.0-30.0, Ni 26.0-35.0, Mo 2.0-6.0, Mn>2.0-6.0, N>0-0.5, C>0-0.05, Si >0-1.0, S>0-0.02, Cu>0-3.0, W>0-6.0, one or more of the elements of the of group Mg, Ce, Ca, B, La, PrZr, Ti, Nd in an amount of up to 2.0 and the balance being Fe and normally occurring impurities and steel making additions.

Description

field of invention [0001] The invention relates to a superaustenitic stainless steel alloy whose composition is balanced in such a way that the alloy and the products manufactured from the alloy meet the following high requirements: high corrosion resistance, especially in inorganic and organic acids and mixtures thereof , excellent general corrosion resistance, excellent structural stability as well as improved mechanical properties and excellent processability, especially specific pipes that can be used in said environment, especially seamless steel pipes and seam welded pipes meet this high demand . Background of the invention [0002] Austenitic steels with the best properties are used in many different applications and are common substitutes such as nickel-based alloys. [0003] The latter has the disadvantage that its price is permanently suppressed due to the raw material. [0004] First, the choice of steel grade is dictated by the requirements for corrosion resist...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C22C38/42C22C38/44C22C38/58
CPCC22C38/42C22C38/44C22C38/005C22C38/58
Inventor 巴巴克·巴哈尔约翰·弗勒迪克帕希·坎加斯乌尔夫·基维塞克
Owner SANDVIK INTELLECTUAL PROPERTY AB
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