CN101187606A - Metallographic etched process for displaying G Cr15 original austenite grain border - Google Patents

Abstract

A metallographic corrosion method for displaying GCr15 original austenitic grain boundaries, which comprises following steps: adding picric acid 5g into distilled water100ml and mixing continuously, then adding sodium dodecyl benzene sulfonate 5ml 50% and mixing, finally adding ferric chloride 2g, and using after placing for 24 hours. A sample is grinded roughly, grinded finely, polished, cleared, blow-dried, immersed into caustic erodent for 2-5 minutes according to a normal method under quenching tempering condition until etched surface is changed into silver grey, washed with flowing water, cleaned with alcohol 95%, and blow-dried. If the sample is over-corroded, polishing paste W0.5-1.0 or metallographic polishing agent 0.5-1.0 is added on silk polishing cloth, the sample is polished slightly with hands, then cleaned with alcohol 95%, and dried. According to practical condition, grain granularity measurement can adopt methods of picture contrast, grid, intercept, quantitative metallography and the like to assess according to relevant standards.

Description

A kind of etching pit method that shows GCr15 original austenite grains border

Technical field

The invention belongs to the heat treatment technics field, specially refer to the etching pit method on a kind of GCr15 of demonstration original austenite grains border.

Background technology

The austenite crystal refinement of steel can improve the intensity of steel effectively.Crystal grain is more tiny, to be subjected to the inhibition of crystal boundary bigger in the expansion of plastic yield under the effect of external force, therefore help improving the intensity of steel, on the other hand, because grain refinement can make wide-angle and low-angle crystal boundary increase again, crackle passes through the energy that crystal boundary consumes to be increased, the propagation rate of crack is slowed down, and simultaneously, austenite grain size also directly has influence on martensitic form, substructure and toughness.The austenite crystal refinement, the also corresponding raising of its toughness.

For many years, thermal treatment worker and scientific research personnel have done a large amount of work for GCr15 bearing steel original austenite grains degree to intensity, toughness and the Fatigue Life of steel both at home and abroad, many achievements in research have also been obtained, but to adopting which kind of etching pit method to show that GCr15 bearing steel original austenite grains border studies not enough, the caustic solution that has can not clearly show crystal boundary, the method that has is too loaded down with trivial details and lose time, the heating that then needs that has could show, and the result is also very undesirable sometimes.Therefore, brought inconvenience and difficult for the refinement of GCr15 bearing steel original austenite grains.

Summary of the invention

At the problems referred to above, the invention provides the etching pit method on a kind of GCr15 of demonstration original austenite grains border, the caustic solution that is adopted can realize showing well at normal temperatures the GCr15 bearing steel original austenite grains border after the tempering of quenching, test condition for the grain refinement treatment process of research bearing steel is provided convenience also provides good foundation for later bearing steel thermal treatment standard revise simultaneously.

For achieving the above object, the present invention has adopted following technical scheme:

The etching pit method on described demonstration GCr15 original austenite grains border comprises mordant prescription, mordant preparation and etching pit three steps, and each step is as follows:

I, mordant prescription

100 milliliters of picric acid 5 grams, 5 milliliters of neopelex 50%W, ferric trichloride 2 grams, distilled water;

II, mordant preparation

1) in 100 milliliters distilled water, adds the picric acid of 5 grams and constantly stirring;

2) neopelex that adds 5 milliliters 50%W in picric solution also constantly stirs;

3) in picric acid that configures and neopelex solution, add 2 ferric trichlorides that restrain;

4) mordant that configures is placed after 24 hours and is used;

III, etching pit

1) sample is roughly ground, fine grinding, polishing, is cleaned and dry up according to conventional method under the Annealed Strip of quenching;

2) sample for preparing is immersed in the mordant, corrode 2～5 minutes, the erosional surface of sample should be placed up and constantly stir or with the continuous wiping of cotton, so that corrosion is even, till erosional surface becomes silver gray;

3) sample that will corrode washes with circulating water, and dries up with 95% alcohol wash;

4) if the sample excessive corrosion can add the antiscuffing paste of W0.5～1.0 or 0.5～1.0 metallurgical polishing agent and carry out slight polishing with hand, and then dry up with the cleaning of 95% alcohol on the real silk polishing cloth;

5) mensuration of grain size can select to adopt methods such as picture pairing comparision, gridding method, intercept method and quantitative metallography to evaluate according to relevant criterion according to actual conditions.

Because adopt aforesaid technical scheme, the present invention has following superiority:

1, do not need heating, can carry out at normal temperatures;

2, not only economy but also save time;

3, can clearly demonstrate the border of GCr15 bearing steel original austenite grains under the Annealed Strip of quenching;

4, reappearance is preferably arranged.

Embodiment

The etching pit method on demonstration GCr15 original austenite grains of the present invention border comprises mordant prescription, mordant preparation and etching pit three steps, and each step is as follows:

I, mordant prescription

100 milliliters of picric acid 5 grams, 5 milliliters of dodecylbenzene sulfonic acid 50%W, ferric trichloride 2 grams, distilled water;

II, mordant preparation

1) in 100 milliliters distilled water, adds the picric acid of 5 grams and constantly stirring;

2) neopelex that adds 5 milliliters 50%W in picric solution also constantly stirs;

3) in picric acid that configures and neopelex solution, add 2 ferric trichlorides that restrain;

4) mordant that configures is placed after 24 hours and is used;

III, etching pit are divided into following 3 kinds of embodiment:

Embodiment 1

1) sample is roughly ground, fine grinding, polishing, is cleaned and dry up according to conventional method under the Annealed Strip of quenching;

2) sample for preparing is immersed in the mordant, corrode 2 minutes, the erosional surface of sample should be placed up and constantly stir or with the continuous wiping of cotton, so that corrosion is even, till erosional surface becomes silver gray;

3) sample that will corrode washes with circulating water, and dries up with 95% alcohol wash;

4) if the sample excessive corrosion can add the antiscuffing paste of W0.5～1.0 or the metallurgical polishing agent of W0.5～1.0 and carry out slight polishing with hand, and then dry up with the cleaning of 95% alcohol on the real silk polishing cloth;

5) mensuration of grain size can select to adopt methods such as picture pairing comparision, gridding method, intercept method and quantitative metallography to evaluate according to relevant criterion according to actual conditions.

This caustic solution has fast, the advantages of simple operation of corrosion speed, may exist austenite grain boundary to manifest incomplete situation, is not suitable for metallographic and takes pictures, but can not have influence on evaluation result.

Embodiment 2

1) sample is roughly ground, fine grinding, polishing, is cleaned and dry up according to conventional method under the Annealed Strip of quenching;

2) sample for preparing is immersed in the mordant, corrode 3～4 minutes, the erosional surface of sample should be placed up and constantly stir or with the continuous wiping of cotton, so that corrosion is even, till erosional surface becomes silver gray;

3) sample that will corrode washes with circulating water, and dries up with 95% alcohol wash;

4) if the sample excessive corrosion can add the antiscuffing paste of W0.5～1.0 or the metallurgical polishing agent of W0.5～1.0 and carry out slight polishing with hand, and then dry up with the cleaning of 95% alcohol on the real silk polishing cloth;

5) mensuration of grain size can select to adopt methods such as picture pairing comparision, gridding method, intercept method and quantitative metallography to evaluate according to relevant criterion according to actual conditions.

This caustic solution has the moderate advantage of corrosion speed, and austenite grain boundary can show fully that suitable metallographic is taken pictures and graded.

Embodiment 3

1) sample is roughly ground, fine grinding, polishing, is cleaned and dry up according to conventional method under the Annealed Strip of quenching;

2) sample for preparing is immersed in the mordant, corrode 5 minutes, the erosional surface of sample should be placed up and constantly stir or with the continuous wiping of cotton, so that corrosion is even, till erosional surface becomes silver gray;

3) sample that will corrode washes with circulating water, and dries up with 95% alcohol wash;

4) if the sample excessive corrosion can add the antiscuffing paste of W0.5～1.0 or the metallurgical polishing agent of W0.5～1.0 and carry out slight polishing with hand, and then dry up with the cleaning of 95% alcohol on the real silk polishing cloth;

5) mensuration of grain size can select to adopt methods such as picture pairing comparision, gridding method, intercept method and quantitative metallography to evaluate according to relevant criterion according to actual conditions.

The suitable austenite crystal of this caustic solution is tiny, the difficult sample to differentiate of crystal boundary.

Claims (1)

1. etching pit method that shows GCr15 original austenite grains border is characterized in that: this method comprises mordant prescription, mordant preparation and etching pit three steps, and each step is as follows:

I, mordant prescription

100 milliliters of picric acid 5 grams, 5 milliliters of neopelex 50%W, ferric trichloride 2 grams, distilled water;

II, mordant preparation

1) in 100 milliliters distilled water, adds the picric acid of 5 grams and constantly stirring;

2) neopelex that adds 5 milliliters 50%W in picric solution also constantly stirs;

3) in picric acid that configures and neopelex solution, add 2 ferric trichlorides that restrain;

4) mordant that configures is placed after 24 hours and is used;

III, etching pit

1) sample is roughly ground, fine grinding, polishing, is cleaned and dry up according to conventional method under the Annealed Strip of quenching;

2) sample for preparing is immersed in the mordant, corrode 2～5 minutes, the erosional surface of sample should be placed up and constantly stir or with the continuous wiping of cotton, so that corrosion is even, till erosional surface becomes silver gray;

3) sample that will corrode washes with circulating water, and dries up with 95% alcohol wash;

4) if the sample excessive corrosion can add the antiscuffing paste of W0.5～1.0 or 0.5～1.0 metallurgical polishing agent and carry out slight polishing with hand, and then dry up with the cleaning of 95% alcohol on the real silk polishing cloth;

5) mensuration of grain size can select to adopt methods such as picture pairing comparision, gridding method, intercept method and quantitative metallography to evaluate according to relevant criterion according to actual conditions.