TWI439550B - Separation of steel intermediates in the material method - Google Patents

Description

Method for separating steel intermediaries

The present invention relates to a method of separating a mediator, and more particularly to a method of separating steel intermediates suitable for use in high carbon steel grades.

Interfacial analysis is a widely used method in the industry to evaluate the cleanliness of steel by extracting fine solid particles such as oxides, silicates, sulfides, and the like formed by refining during steelmaking. Nitrogen, etc., intervenes in the matter, and analyzes the content, composition, or size of the intervening material to determine the mechanical properties and processing characteristics of the steel.

In the past, the low-temperature weak acid solution was used to soak the steel to be analyzed, and the acid solution in which the steel to be analyzed was dissolved was separated by filtration and extracted to obtain one of the main methods for separating the steel. However, in addition to the extremely long dissolution and filtration time, such acid-soluble extraction method must also be washed with a large amount of acid solution due to incomplete dissolution of the steel to be analyzed, and environmentally-friendly acid waste liquid is generated. problem.

Therefore, the Japanese Patent Application No. 095149945 discloses a method for extracting steel by acid-soluble extraction to solve the above problems. The method disclosed in the present invention is that after the steel embryo is dissolved into a first solution by, for example, a low-temperature acid solution, the filtrate is filtered and dried to obtain a first powder, and then the first powder is subjected to reduction reaction and purification, and then The acid solution dissolves and purifies the purified first powder to form a second solution, and finally the second solution is filtered and the filtrate is dried to obtain a second powder containing the intervening substance, and then the intervening component is further applied to the second powder. Analysis, measurement.

The application No. 095149945 uses an acid-soluble extraction and a reduction reaction and a purification step to obtain a mediation technique. Although it can solve the environmental problem of generating a large amount of acid waste liquid in the whole process in the past, the separation carbon content is more than 0.3 wt%. When the high-carbon steel is intervened in the material, a large amount of carbon in the steel will cause a large amount of carbides, graphite, or carbon-containing compounds that cannot be completely dissolved in the acid solution to block the filter paper filter pores, so that the filtration time It is too long to even filter out the effective intervening content, which in turn affects the mechanical properties of the subsequent steel and the judgment of processing characteristics.

Accordingly, it is an object of the present invention to provide a method for separating steels which are suitable for separating high-carbon content steels.

Thus, the method of the present invention for separating steel intermediates comprises a heat treatment process and an extraction process.

The heat treatment process is to apply a solution heat treatment to a steel embryo to dissolve the carbon-containing compound in the steel embryo, and/or graphite to the base phase, and then quench the mixture to obtain a proportion of the carbonite (Fe ₃ ) content. Reduced steel test pieces.

The extraction process extracts and separates the above-mentioned steel test piece having the reduced ferritic carbon content by an acid solution to obtain a mesoscopic sample.

The object of the present invention and solving the technical problems thereof can also be further implemented by the following technical measures.

Preferably, the solution heat treatment in the heat treatment process is carried out at a temperature not lower than 50 ° C above the solid solution temperature of the steel for at least 30 minutes.

Preferably, in the heat treatment process, after solution heat treatment, the temperature is lowered to 25 to 35 ° C to quench the steel test piece.

More preferably, the steel embryo has a carbon content of not less than 0.8 wt%.

Preferably, the steel blank is selected from the group consisting of: 1080S steel, and SUJ2 steel.

Preferably, the extraction process extracts the steel test piece with a nitric acid solution.

The effect of the invention is that the high-carbon content steel embryo is subjected to a heat treatment process, so that the carbide, graphite or carbon-containing compound which cannot be completely dissolved in the acid solution in the steel embryo is reduced due to solid solution to the base phase, and the extraction is avoided. During the process, the filter paper filter pores are precipitated to affect the extraction of the intervening material, which makes it difficult to analyze the physical properties and processing characteristics of the steel.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.

Referring to FIG. 1, a preferred embodiment of the method for separating steel intervening materials of the present invention comprises a heat treatment process 1 and an extraction process 2, which are suitable for separating steel embryos with high carbon content steels, especially carbon content of not less than 0.8 wt. % of high carbon content steels, such as 1080S steel, SUJ2 steel for subsequent analysis, or evaluation of steel properties or processing applications, and in the following description, is to separate steel with a carbon content of 1.0 wt% The medium in the embryo is described.

First, the steel preform having a carbon content of 1.0 wt% is subjected to a heat treatment process 1, and the steel embryo is heated at a heating rate of 100 to 200 ° C / min to a temperature not lower than the solid solution temperature (A _CM temperature) of 50 ° C or more, followed by solution heat treatment. After 30 minutes, the carbide, graphite, or carbon-containing compound in the steel embryo is solid-dissolved into the base phase. Immediately after quenching to room temperature (about 25 to 35 ° C), a steel test piece in which the celite carbon phase disappeared or the ratio was lowered was obtained.

The heat treatment process 1 converts the prosthetic ferritic carbon and the Pearlite in the original steel embryo into a Martensite, so that the carbon element is supersaturated and dissolved in iron (base phase). This avoids the precipitation of carbides, graphite, or carbon-containing compounds in a solid phase in subsequent processes.

The steel test piece obtained by the heat treatment process 1 can be subjected to an extraction process 2, wherein the steel test piece is dissolved by an acid solution to separate and purify the intervening substance without (or to a minimum The presence of carbides, graphite, or precipitation of carbonaceous compounds causes the filtration separation step to become clogged, resulting in a process interruption or an excessively long period of time.

In more detail, the extraction process 2 is first to remove the grease or metal shavings on the surface of the steel test piece by pickling with a hydrochloric acid solution at room temperature (about 25 to 35 ° C) and 37 v/o, and then weigh the steel test piece; Stirring in a nitric acid solution at a temperature of 60 ° C and 9.25 v/o while maintaining the temperature at 60 ° C until the steel test piece is completely dissolved in the nitric acid solution, and finally filtering the filter with filter paper without clogging the filter paper. Then, purifying and drying the filtrate, the powder sample finally including the intervening material can be obtained, and the subsequent material composition analysis and measurement can be performed on the powder sample to obtain the purity in the original steel material, and Evaluate the mechanical properties and processability of this steel for the next processing application and product manufacturing.

The inventor's research suggests that the Bora iron and the ferritic carbon-iron structure are the microstructures of typical high-carbon steels, as shown in Figures 2 and 3. The Borne iron is mainly composed of Ferrite and part of Xueming. Carbon iron consists of a steel with a carbon content of about 1.0 wt%. The snowy carbon phase at room temperature is about 15 wt%, and the snowy carbon phase is the high carbon content of the steel embryo dissolved in the acid solution. The solid matter such as carbonaceous compounds or graphite that clogs the filter paper during filtration causes the filtration effect in the extraction process 2 to be poor, and even the biggest reason for the smooth filtration separation.

Compared with the microstructure of the steel test piece after the heat treatment process 1 of the present invention (see FIGS. 4 and 5), the present invention uses the heat treatment process 1 to eliminate the original wave-forming iron structure and the preliminary precipitation of ferritic carbon. Instead, the carbon-supersaturated solid solution of the granulated iron structure in the base phase can avoid the occurrence of poor separation efficiency such as incomplete filtration and inability to filter in the extraction process 2.

The present invention will be further illustrated and verified by the following experimental examples to further understand the industrial benefits of the present invention.

[Experimental Example 1] Separation of mediators in steel embryos of 1080S high carbon steel

Steel component of 1080S high carbon steel (iron is balanced, not recorded, wt%)

<control group>

The steel embryo is subjected to an extraction process, firstly picking and cleaning the steel embryo with 37 v/o hydrochloric acid at room temperature, and then weighing the steel embryo completely in a nitric acid solution at 60 ° C, 9.25 v/o, and then After filtering with a filter paper having a pore size of 1 μm to obtain a filtrate, the filter and the filter paper were placed in a heating furnace, subjected to ashing treatment at 800 ° C for 2 hours, and then hydrogen gas was introduced at 600 ° C for 2 hours. After the hydrogen reduction treatment, the residual iron oxide is reduced to pure iron, and then the product after the hydrogen reduction treatment is repeated once for the above-mentioned nitric acid solution, filter paper filtration, and ashing treatment to obtain a final intervening powder sample.

<experimental group>

According to the method of the present invention for separating steel intermediates, the steel embryo is first heated to 950 ° C at a heating rate of about 100 ° C / min, and subjected to solution heat treatment at a high temperature of 950 ° C for 30 minutes and then quenched to about 30 ° C to obtain The steel test piece was then subjected to the same extraction process as the above-mentioned control group, that is, the steel test piece was firstly pickled by pickling with 37 v/o hydrochloric acid at room temperature, and then weighed, and then the steel test piece was completely dissolved. In a nitric acid solution of 60 ° C and 9.25 v/o, the filter was filtered with a filter paper having a pore size of 1 μm to obtain a filtrate. The filter and the filter paper were placed in a heating furnace and subjected to ashing at 800 ° C for 2 hours. Then, hydrogen is introduced into the hydrogen at 600 ° C for 2 hours, and the residual iron oxide is reduced to pure iron, and then the product of the hydrogen reduction treatment is repeated once for the above-mentioned nitric acid solution, filter paper filtration, and ashing treatment. After that, a final intervening powder sample was obtained.

Experimental result

It is found from the experimental results that the filtration time required for the separation of the steel embryos by the present invention is shortened by more than half, which proves that the present invention can indeed improve the steel embryo of the high carbon steel species because of the carbon content problem when separating the intermediaries. The clogging of the filter paper that occurs during the filtration occurs, resulting in an extended filtration time and even the inability to filter out the problem of effective intervening content.

[Experimental Example 2] Separation of intercalates in steel embryos of SUJ2 high carbon steel

Steel composition of SUJ2 high carbon steel (iron is the balance, not recorded, wt%)

<control group>

The steel embryo is subjected to an extraction process, firstly picking and cleaning the steel embryo with 37 v/o hydrochloric acid at room temperature, and then weighing the steel embryo completely in a nitric acid solution at 60 ° C, 9.25 v/o, and then After filtering with a filter paper having a pore size of 1 μm to obtain a filtrate, the filter and the filter paper were placed in a heating furnace, subjected to ashing treatment at 800 ° C for 2 hours, and then hydrogen gas was introduced at 600 ° C for 2 hours. After the hydrogen reduction treatment, the residual iron oxide is reduced to pure iron, and then the product after the hydrogen reduction treatment is repeated once for the above-mentioned nitric acid solution, filter paper filtration, and ashing treatment to obtain a final intervening powder sample.

<experimental group>

According to the method of the present invention for separating steel intermediaries, the steel embryo is first heated to 950 ° C at a heating rate of about 100 ° C / min, and subjected to solution heat treatment at a high temperature of 950 ° C for 30 minutes and then quenched to about 30 ° C, followed by quenching to about 30 ° C, followed by The same extraction process as the above control group was carried out, that is, the steel test piece was first pickled by pickling with 37 v/o hydrochloric acid at room temperature, and then weighed, and then the steel test piece was completely dissolved at 60 ° C, 9.25 v. In the nitric acid solution of /o, the filter is obtained by filtering the filter paper having a pore size of 1 μm, and then the filter and the filter paper are placed in a heating furnace to carry out ashing treatment at 800 ° C for 2 hours, and then hydrogen is introduced. The hydrogen reduction treatment at 600 ° C for 2 hours is carried out, and the residual iron oxide is reduced to pure iron, and then the product after the hydrogen reduction treatment is repeated once for the above-mentioned nitric acid solution, filter paper filtration, ashing treatment, and finally In the powder sample.

Experimental result

From the experimental results, it was found that the steel embryos (ie, the control group) which were not subjected to the present invention could not be smoothly filtered and separated by the filter paper, and the experiments conducted in the present invention were filtered in 3 hours and separated. The 6.2 mg of the interstitial powder sample again demonstrates that the present invention does solve the filtration problems encountered in the extraction and separation of high carbon steels by conventional methods.

In summary, the present invention is obtained by first solidifying heat treatment of a steel embryo and quenching, so that the carbonaceous compound or graphite in the steel embryo is solid-solved into the base phase, and the subsequent extraction process is not due to high carbon content. A large amount of carbides and graphite which cannot be dissolved in the acid solution for extraction are precipitated, which causes clogging of the filter paper filter pores during filtration and separation, resulting in a long filtration time and even incapability of filtering out an effective intervening sample. The object of the invention is achieved.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

1. . . Heat treatment process

2. . . Extraction process

Figure 1 is a flow chart illustrating a preferred embodiment of the method of separating steel intervening materials of the present invention

Figure 2 is a microscopic phase diagram showing the Borne iron structure exhibited by a high carbon content steel embryo;

Figure 3 is a microscopic phase diagram illustrating the high magnification image of Figure 2;

Figure 4 is a microscopic phase diagram showing the granulated iron structure of the high carbon content steel embryo after hot processing; and

Figure 5 is a microscopic phase diagram illustrating the high magnification image of Figure 4.

1. . . Heat treatment process

2. . . Extraction process

Claims (6)

A method for separating steel intermediaries, suitable for extracting a medium in a steel embryo, comprising: a heat treatment process, performing a solution heat treatment on the steel embryo to solidify carbon and carbide in the steel embryo to a base phase After quenching, a steel test piece having a reduced proportion of ferritic carbon and iron is obtained; and an extraction process is performed, and the steel test piece is extracted with an acid solution to separate the intervening substance in the steel test piece. The method of separating steel intermediaries according to claim 1, wherein the solution heat treatment in the heat treatment process is carried out at a temperature not lower than 50 ° C above the solid solution temperature of the steel for at least 30 minutes. The method for separating steel intermediaries according to claim 2, wherein the heat treatment process is subjected to solution heat treatment and then cooled to 25 to 35 ° C to quench to form a steel test piece. The method for separating steel intermediaries according to claim 3, wherein the steel embryo has a carbon content of not less than 0.8 wt%. The method for separating steel intermediaries according to claim 4, wherein the steel embryo is selected from the group consisting of 1080S steel, and SUJ2 steel. The method for separating steel intermediaries according to claim 5, wherein the extraction process extracts the steel test piece with a nitric acid solution.