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Method for displaying two-phase grain boundary of duplex stainless steel

A technology of duplex stainless steel and grain boundary, which is applied in the preparation of test samples, etc., can solve the problems of not being able to display the two-phase grain boundary of duplex stainless steel, requiring electricity, and time-consuming, and achieving the effect of good microstructure observation.

Active Publication Date: 2014-05-14
SHANXI TAIGANG STAINLESS STEEL CO LTD
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Problems solved by technology

During the inspection, methods such as electrolysis of 10% oxalic acid aqueous solution, hot or boiling alkaline potassium ferricyanide solution and 40% sodium hydroxide (potassium) solution are generally used. These methods can show both austenite and ferrite. The phase boundary of the duplex stainless steel is used to measure the phase ratio and observe the precipitated phase. The disadvantage is that special instruments are required, time-consuming and electricity is required, especially the two-phase grain boundary of duplex stainless steel cannot be displayed, and the grain size is observed.

Method used

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  • Method for displaying two-phase grain boundary of duplex stainless steel
  • Method for displaying two-phase grain boundary of duplex stainless steel
  • Method for displaying two-phase grain boundary of duplex stainless steel

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Embodiment

[0025] The selected material is super duplex stainless steel 2906 plate, and the specific chemical composition (mass percentage%) is:

[0026] C 0.018, Si 0.56, Mn 0.96, Cr 29.38,

[0027] Ni 6.62, Mo 2.2, N 0.34,

[0028] The balance is Fe and unavoidable impurities.

[0029] The thickness of the steel plate is 15 mm, the size of the metallographic sample is a square of 15 × 10 × 15 mm, the state is hot-rolled and annealed at different solution temperatures, and the model of the metallographic analysis instrument is Lei DM4000.

[0030] The specific operation steps of this embodiment are as follows:

[0031] Ⅰ. Preparation of metallographic samples

[0032] (1) Metallographic samples are taken by machining and sawing. The size of the sample should be suitable for metallographic observation, usually a cylinder of φ15×20 mm (or a cube of 15×10×20 mm). High can cause microstructural changes or plastic deformation due to stress.

[0033] (2) Grind off the unnecessary sharp c...

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Abstract

The invention relates to a method for displaying two-phase grain boundary of duplex stainless steel. The method comprises the following steps: I, preparation of a metallographic sample, namely, (1) cutting the metallographic sample by adopting a machining saw; (2) roughly grinding the observation surface of the sample; (3) mechanically polishing the observation surface of the sample by adopting a metallographic polishing machine; (4) finely polishing the observation surface by the metallographic polishing machine; (5) cleaning the observation surface of the sample with ethyl alcohol; II, preparation of a corrosive agent, namely, preparing a mixed solution from 10-15g of copper sulfate, 50 mm <3> of nitric acid with the volume percentage being 65-68% and 100-150 mm <3> of hydrochloric acid with the volume percentage being 36-38%; III, corrosion of the metallographic sample, namely, putting the metallographic sample into a metallographic corrosive agent, taking out the duplex stainless steel when the metallographic observation surface is corroded to be deep silver gray, cleaning the sample with water, and wiping the observation surface of the metallographic sample by degreasing cotton dipped with absolute ethyl alcohol. The method for displaying two-phase grain boundary of duplex stainless steel can be used for quickly, simply and conveniently displaying the two-phase grain boundary of the duplex stainless steel.

Description

technical field [0001] The present invention relates to a method of revealing two-phase grain boundaries of duplex stainless steel. Background technique [0002] Duplex stainless steel, also known as ferritic-austenitic stainless steel, has many characteristics of ferritic steel and austenitic steel, and is widely used in sour oil, gas fields, transportation, oil refining, petrochemical and marine engineering. In the production of duplex stainless steel, it is often necessary to check the metallographic structure of the material, and then achieve the desired performance by properly adjusting the composition and production process. During the inspection, methods such as electrolysis of 10% oxalic acid aqueous solution, hot or boiling alkaline potassium ferricyanide solution and 40% sodium hydroxide (potassium) solution are generally used. These methods can show both austenite and ferrite. The phase boundary of the duplex stainless steel is used to measure the phase ratio and...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N1/32
Inventor 李建春贾元伟张寿禄廉晓洁
Owner SHANXI TAIGANG STAINLESS STEEL CO LTD
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