KR20180006854A - Carbon steel material before heat treatment and carbon steel material after heat treatment having excellent scale removability and method for preparing the same, method for removing scale, and film forming agent eatsy to remove scale - Google Patents

Abstract

Provided is a new technology, easily removing scale generated by heating of a steel material. According to a steel material before heat treatment having a film formed on a surface of carbon steel, the carbon steel comprises at least 0.06 wt% of carbon based on total mass of the carbon steel. The film comprises: at least one type of metal element (X) selected from iron (Fe), nickel (Ni), and cobalt (Co); and at least one type of metal element (Y) selected from titanium (Ti); zirconium (Zr); hafnium (Hf); niobium (Nb); vanadium (V); chromium (Cr); manganese (Mn); molybdenum (Mo); and tungsten (W). Moreover, the present invention relates to the steel material before heat treatment, wherein an attachment combined amount of the metal element (Y) is 1-100 mg/m^2, and a mass ratio (X)/(Y) of the metal element (X) and the metal element (Y) is in a range from 0.01 to 0.5.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a carbonaceous material, a carbonaceous material, a carbonaceous material, a carbonaceous material, a carbonaceous material and a method for producing the carbonaceous material. METHOD FOR PREPARING THE SAME, METHOD FOR REMOVING SCALE, AND FILM FORMING AGENT EATSY TO REMOVE SCALE}

The present invention relates to a technique for facilitating removal of a scale generated when a carbon steel is heat-treated.

In order to improve the mechanical strength, the metal material is subjected to heat treatment by heating and cooling. The conditions of the heat treatment differ depending on the intended mechanical strength, material, shape, and constraints of the equipment, but in the case of steel, the steel material is heated to a temperature higher than about 700 캜. Therefore, a steel material heated to a high temperature under the atmosphere is scaled by surface oxidation while being heated. If such a scale remains on the surface of the steel, there is a problem that the quality is deteriorated, such as the appearance defects, the dimensional accuracy, and the influence on the surface roughness. Therefore, conventionally, scale removal such as pickling or shot blasting is performed after the heat treatment of the steel material.

Also, as disclosed in Patent Document 1, there is also proposed a technique capable of suppressing the occurrence of scale amount in heating in an atmospheric furnace by controlling the amount of Si and the amount of Cr of the steel material and further controlling the surface roughness to a certain range have.

On the other hand, as disclosed in Patent Document 2, by applying a high temperature decarburization preventing paint containing a composition containing silicon carbide to a steel material, it is possible to prevent oxidation and decarburization and further improve the removability of the coating film after heat treatment Techniques have also been proposed.

Japanese Patent Application Laid-Open No. 2005-133180 Japanese Unexamined Patent Application Publication No. 2-205622

The present invention aims to provide a new technique capable of easily removing scales generated by heating a steel material.

As a result of intensive studies, the inventors of the present invention have found that the above-described problems can be solved by the following method, thereby completing the present invention.

[1] In a steel before heat treatment having a coating on the surface of carbon steel,

Wherein the carbon steel contains 0.06 mass% or more of carbon based on the total mass of the carbon steel,

Wherein the film contains at least one metal element (X) selected from Fe, Ni and Co and at least one metal element (Y) selected from Ti, Zr, Hf, Nb, V, Cr, Mn, And also

(X) / (Y), which is a mass ratio of the metal element (X) to the metal element (Y), is in a range of 0.01 to 0.5, wherein the total amount of the metal element (Y) adhered is 1 to 100 mg / Pre-annealed steel.

[2] A method for producing a steel material before heat treatment,

Wherein the steel before the heat treatment has a coating on the surface of the carbon steel,

Wherein the carbon steel contains 0.06 mass% or more of carbon based on the total mass of the carbon steel,

Wherein the film contains at least one metal element (X) selected from Fe, Ni and Co and at least one metal element (Y) selected from Ti, Zr, Hf, Nb, V, Cr, Mn, And also

(X) / (Y) in a mass ratio of the metal element (X) and the metal element (Y) is in the range of 0.01 to 0.5, and the total amount of the metal element (Y) is 1 to 100 mg /

The above-

(Y) selected from Ti, Zr, Hf, Nb, V, Cr, Mn, Mo and W and an etching component to the carbon steel to form the coating film Wherein the pre-heat treatment is performed at a temperature of not less than < RTI ID = 0.0 >

[3] A method of manufacturing a steel material after heat treatment,

At least one metal element (X) selected from Fe, Ni and Co and at least one metal element selected from Ti, Zr, Hf, Nb, V, Cr, Mn, Mo and W on the surface of carbon steel containing 0.06% (X) being a mass ratio of the metal element (X) to the metal element (Y), wherein the total amount of adhesion of the metal element (Y) is 1 to 100 mg / / (Y) in the range of 0.01 to 0.5 to obtain a steel material before heat treatment,

And heat treating the steel material before the heat treatment at 700 ° C or higher.

[4] A method for removing scale,

At least one metal element (X) selected from Fe, Ni and Co and at least one metal element (Y) selected from Ti, Zr, Hf, Nb, V, Cr, Mn, Mo, To obtain a steel material before the heat treatment,

A step of heating the steel material before the heat treatment at 700 DEG C or higher to obtain a steel material after the heat treatment,

And removing the scale attached on the steel material after the heat treatment.

[5] The method of removing scale as described in [4], wherein the carbon steel contains 0.06% by mass or more of carbon, based on the total mass of the carbon steel.

[6] The method according to any one of [1] to [6], wherein the total amount of the adhesion of the metal element (Y) is 1 to 100 mg / m 2 and the mass ratio of the metal element (X) , [4] or [5].

[7] A preparation for forming a descaling-easy film on a carbon steel constituting a steel material before the heat treatment, wherein the steel material is obtained by heating the steel material before the heat treatment to 700 ° C. or higher and obtaining the steel material after the heat treatment,

At least one metal element (Y) selected from Ti, Zr, Hf, Nb, V, Cr, Mn, Mo and W,

Wherein the film has an etching component.

[8] The method of claim 1, wherein the descalability facilitating film comprises at least one metal element (X) selected from Fe, Ni and Co and at least one metal selected from Ti, Zr, Hf, Nb, V, Cr, Mn, An agent for forming a descaling-easy film of [7], which contains the element (Y).

[9] The agent for forming a descaling-easy film as described in [7] or [8], wherein the carbon steel contains 0.06% by mass or more of carbon based on the total mass of the carbon steel.

(X) / (Y), which is a mass ratio of the metal element (X) and the metal element (Y) is in the range of 0.01 to 0.5, and the total amount of the metal element (Y) adhered is 1 to 100 mg / , [8] or [9].

According to the present invention, it is possible to provide a new technique capable of easily removing (for example, easily removing with air blow or running water) a scale generated by heating a steel material. Therefore, compared with conventional scale removal such as pickling or shot blasting, it is possible to dramatically simplify and shorten the processing steps.

Hereinafter, a method of manufacturing a steel material before heat treatment, a method of producing a steel material before heat treatment (as well as a preparation used in the production method), and a method of manufacturing a steel material after heat treatment by heating the steel material before heat treatment .

«1. Steels before heat treatment »

The pre-heat treated steel material according to the present invention is a pre-heat treated steel material having a coating on the surface of carbon steel, wherein the carbon steel contains 0.06 mass% or more of carbon based on the total mass of the carbon steel, And at least one metal element (X) selected from Co, and at least one metal element (Y) selected from Ti, Zr, Hf, Nb, V, Cr, Mn, Mo and W, (X) / (Y) in the mass ratio of the metal element (X) to the metal element (Y) is in the range of 0.01 to 0.5. Hereinafter, each component will be described in detail.

<1-1. Carbon steel>

The carbon steel constituting the steel before heat treatment according to the present invention contains 0.06 mass% or more of carbon based on the total mass of the carbon steel. Preferably 0.06 mass% or more and 3.1 mass% or less, more preferably 0.1 mass% or more and 0.77 mass% or less, and more preferably 0.15 mass% or more and 0.45 mass% or less. It is possible to extremely easily remove the scale adhered to the steel material after the heat treatment by attaching a specific amount of the coating film described below within the range of the carbon content in the carbon steel. The carbon steel may contain elements other than Fe and C, such as Ni, Co, Mo, V, Ti, Nb, Mn, Cr and B, for example.

<1-2. Coating>

{1-2-1. ingredient}

The coating constituting the steel before heat treatment according to the present invention is characterized in that at least one metal element (X) selected from Fe, Ni and Co and at least one element selected from Ti, Zr, Hf, Nb, V, Cr, Mn, Mo and W And at least one kind of metal element (Y). Here, as the metal element (X), Fe and Ni are suitable, and Fe is more suitable in that the metal element (X) can be extremely easily peeled off by air blow or the like and can form a coating film which is easier to descale. Ti, Zr, Nb, Cr and Mo are suitable as the metal element Y from the viewpoint of being capable of extremely easily peeling off with air blow or the like, Ti is more suitable. In addition, both of the metal element (X) and the metal element (Y) may contain only one of them and may contain a plurality of species. It is presumed that these metal elements are present in the coating film in the presence of metal, hydroxide, hydrated oxide and oxide.

{1-2-2. Component ratio}

The mass ratio (X) / (Y) of the metal element (X) to the metal element (Y) is in the range of 0.01 to 0.5, preferably in the range of 0.05 to 0.3, More suitable. Within this range, aggregation cracking of the coating film can be effectively prevented.

{1-2-3. Adhesion amount}

The adhesion amount of the coating constituting the steel constituting the steel before heat treatment according to the present invention with respect to carbon steel is such that the total amount of adhesion of the metal element Y is 1 to 100 mg / m 2 and the total adhesion amount of the metal element Y is 2 - More preferably 40 mg / m 2, and more preferably 5 to 20 mg / m 2 of the total amount of the metal element (Y). Since the metal element (Y) is introduced into the scale produced in the heat treatment, the scale attached to the steel after the heat treatment can be extremely easily removed. Therefore, it is preferable that the coating constituting the steel material before heat treatment according to the present invention is free from film cracks and coatings. When the total adhesion amount of the metal element (Y) exceeds 100 mg / m 2, film cracks tend to occur. Since the metal element (Y) is hardly introduced into the scale generated in the heat treatment at the position of the film crack, the scale can not be easily removed. If the total amount of the metal element (Y) is less than 1 mg / m 2, the surface of the carbon steel can not be covered with the coating film, so that the coating film tends to be omitted. In the portion where the film is missing, the metal element (Y) is not introduced into the scale generated in the heat treatment, so that the scale can not be easily removed. When the carbon content in the carbon steel is within the above range, the scale attached to the steel after the heat treatment can be extremely easily removed by adhering the coating to the above range. The deposition amount of the metal element (Y) can be measured from the surface of the carbon steel material by a fluorescent X-ray analyzer (XRF). The deposition amount of the metal element X can be measured by X-ray photoelectron spectroscopy (XPS) at each depth of the coating. In the present invention, the oxygen decay position in the depth profile of the XPS is defined as the boundary between the carbon steel and the coating , And the average of the measured values of the metal element (X) detected in the upper layer is defined as the deposition amount of the metal element (X).

«2. Method of manufacturing steel before heat treatment »

A method of manufacturing a pre-heat treated steel material according to the present invention is characterized in that a preparation containing at least one metal element (Y) selected from Ti, Zr, Hf, Nb, V, Cr, Mn, To form the coating film. Hereinafter, the preparation (preparation for easy descaling) used in the production of the steel before heat treatment will be described first, and then each step will be described.

<2-1. Ease of descaling> Formulation for film formation>

{2-1-1. ingredient}

(2-1-1-1. Metal Elements)

The easy descaling film-forming agent according to the present invention contains at least one metal element (Y) selected from Ti, Zr, Hf, Nb, V, Cr, Mn, Mo and W. Here, Ti, Zr, Nb, Cr, and Mo are suitable as the metal element, and Zr and Ti are more suitable. Suitable reasons are as described above. In this case, the concentration of the metal element (Y) in the agent for forming a scalpel easy film is suitably 0.5 to 10 mmol / l. These metal elements may be supplied from the base material or may not be in a normally dissolved state. Basically, these metal elements are present in a state dissolved in a liquid medium described later. The metal element may be either one kind or a plurality of kinds. The metal element is essential, but may contain other metal elements. Concretely, it may contain at least one metal element (X) selected from Fe, Ni and Co. The concentration of the metal element (X) in the agent for forming a film to be descaled easily is suitably 0.1 to 5 mmol / l.

(2-1-1-2. Etching component)

The formulation for easy descalability coating of the present invention contains an etching component. Here, the etching component is not particularly limited as long as it is an additive component capable of etching carbon steel, and examples thereof include inorganic acids such as HNO ₃ , HF, H ₂ SO ₄ and HCl. Of these, HNO ₃ , HF and H ₂ SO ₄ are suitable from the standpoint of stabilizing the film-forming treatment agent, and HF alone or a combination of HF and HNO ₃ is more suitable. The presence of the etching component in the descalability easy film-forming preparation can be determined in relation to the appropriate pH range (2.5 to 4.5) and the kind and amount of other existing components. For example, when the acid is used as the additive component, the dissociated form of the acid is assumed. The etching component may be one species or may contain a plurality of species.

(2-1-1-3. Other Ingredients)

The preparations for forming a descaling-easy film according to the present invention may contain other components, if necessary. For example, the addition of alkali to control the pH to a suitable range, LiOH, NaOH, a strong alkali such as KOH, NH ₃ {ammonium hydroxide (NH ₃ -H ₂ O)} can be used and a weak alkali, such as When adding an acid, a weak acid such as acetic acid can be used. NH ₃ (ammonium hydroxide (NH ₃ -H ₂ O)} is preferable as the alkali, and weak acid is preferable as the acid.

(2-1-1-4. Liquid medium)

The liquid medium in the formulation for easy descaling of a coating film according to the present invention is preferably a liquid medium (for example, deionized water, pure water) mainly composed of water. Means that the content of water is 51 mass% or more (preferably 60 mass% or more, more preferably 70 mass% or more, more preferably 80 mass% or more, Particularly preferably not less than 90% by mass). Further, the liquid medium may contain a liquid medium other than water (for example, a water-miscible liquid medium, for example, alcohol such as ethanol). The formulation may also be in a dry form or in a concentrated form. In this case, it should be dissolved or diluted with water in the field.

{2-1-2. Liquid}

(2-1-2-1. PH)

The pH of the descaling-easy film-forming preparation of the present invention is suitably 2.5 to 4.5, more preferably 3 to 4. This pH is a value measured at a treatment temperature (typically 40 ° C) according to JIS-Z8802: 2011 for a drug for forming a scalpel easy film.

{2-1-3. Manufacturing Method}

A production method of a descalability easy film forming agent according to the present invention is characterized by comprising a supply source of at least one metal element (Y) selected from Ti, Zr, Hf, Nb, V, Cr, Mn, Mo and W, To a liquid medium, and mixing. Hereinafter, the supply source will be described in detail.

(Source 2-1-3-1)

As the source of the metal element Y, for example, a salt, a complex compound or a metal hydride oxide containing at least one metal element (Y) selected from Ti, Zr, Hf, Nb, V, Cr, Mn, . Specifically, in the case of Ti, for example, titanium oxyiodo oxalate is ammonium, titanium oxyoxalate is potassium, titanium oxide (II), titanium oxide (III), titanium oxide (IV), titanium titanium oxide sulfate, , Titanium (IV) bromide, metatitanic acid, zinc metatitanate (II), aluminum titanate (III), potassium metatitanate, metatitanic tricalcium (II), titanium zirconium, strontium metatitanate, (III), copper metatitanate (II), sodium titanate, neodymium titanate (III), barium metatitanate, bismuth metatitanate (III), magnesium metatitanate, magnesium titanate, metatitanic acid (II), titanium scandium (III), lithium metatitanate, ammonium hexafluorotitanium (IV), potassium hexafluorotitanate (IV), titanium (IV) Titanium (IV) sulfate, titanium chloride, titanium nitrate, titanyl sulfate, fire Titanium (III), fluoride titanium (IV), hexafluoro titanate, titanium lactate, titanium buffer oxo acid, titanium laurate, titanium acetylacetonate, and titanium salts such as titanium hydroxide (IV) or titanium salts, and the like; Zirconium (IV) chloride, zirconium (IV) chloride, zirconium silicate, zirconium (IV) acetate, zirconium (IV) oxide, nitric oxide (II), meta zirconium aluminum (III), calcium metazirconate, cobalt (II) methazirconium, strontium metazirconate, meta zirconium oxide, meta zirconium (II), sodium metazirconate, nickel (II) methazirconate, barium metazirconium, bismuth metazirconium (III), magnesium metazirconate, zirconium oxycarbonate, hexafluorozirconium (IV), basic zirconium carbonate, basic zirconium carbonate, zirconium carbonate, ammonium zirconium carbonate, zirconium carbonate, zirconium nitrate, zirconium nitrate, sulfur Zirconium salts such as zirconium (IV) sulfate, zirconyl sulfate, hexafluorozirconium acid, zirconium oxyphosphate, zirconium pyrophosphate, zirconium dihydrogenphosphate, zirconium oxychloride, zirconium fluoride, zirconium acetate, zirconium oxide and zirconium hydroxide ; In the case of Hf, it is possible to use tetrakis (acetylacetonato) hafnium (IV), hafnium chloride (IV), hafnium oxide (IV), hafnium iodide, hafnium sulfate (IV), hafnium nitrate IV), fluoro hafnium acid, fluoro hafnium salt, hafnium salt such as hafnium fluoride, etc., or hafnium salt; In the case of Nb, it is possible to use niobium oxide (II), niobium oxide (V), niobium oxalate (niobium oxalate), niobium hydroxide (V), niobium oxyacetylacetonate, methaniobic acid, calcium metaniobium, Niobium salts such as barium niobate, magnesium methanioblicide, lithium metaniobic acid, ammonium metaniobic acid, sodium sodium methaniobate, and niobium pentachloride; (III), vanadium bromide (III), vanadium oxoylate, vanadium iodide (II), vanadium pentoxide, metavanadic acid, pyrovanadium (III) There may be mentioned, for example, sodium, potassium, sodium, sodium, sodium vanadium, ammonium metavanadate, sodium metavanadate, potassium metavanadate, vanadium trichloride, vanadium trioxide, vanadium dioxide, vanadium oxysulfate, vanadium acetylacetate, vanadium molybdic acid Vanadium salts and the like or vanadates; chrome; In the case of Cr, chromium (III) formate, chromium (III) chloride, chromium (III) chloride, chromium (III) oxalate, chromium (III) III), chromium (III) chloride, chromium (III) chloride, chromium (III) chloride and the like; Manganese (II), manganese oxide (II), manganese (III) oxide, manganese (IV) oxide, manganese (II) bromide, manganese (II) oxalate, (II), manganese sulfate (II), manganese sulfate (III), manganese sulfate (III), manganese sulfate (IV), fluoride (III) (II), manganese fluoride (III), manganese (II) carbonate, manganese (II) acetate, manganese (III) acetate, ammonium manganese (II) sulfate, manganese Hepatitis or manganate; In the case of Mo, a molybdenum compound such as molybdenum chloride (V), molybdenum oxide (IV), molybdenum oxide (VI), zinc molybdate (II), potassium molybdate, calcium molybdate, cobalt molybdate (II) (II), barium molybdate, bismuth molybdate (III), magnesium molybdate, lithium molybdate, lithium paramolybdate, strontium molybdate, ammonium molybdate, sodium molybdate, molybdate, Molybdenum salts such as ammonium molybdate, ammonium paramolybdate, and sodium molybdate, or molybdates; In the case of W, tungsten chloride (VI), tungsten (III) oxide, tungsten (VI) chloride, tungsten chloride, tungsten dioxide, tungsten trioxide, metatungstic acid, ammonium metatungstate, sodium metatungstate, (II) tungstate, tungstic acid, copper (II) tungstate, nickel tungstate (II), tungstate , Tungsten salts such as barium tungstate, magnesium tungstate, manganese (II) tungstate, lithium tungstate, cesium tungstate, ammonium tungstate, sodium tungstate, or tungstate.

<2-2. Each step in the method of producing the steel before heat treatment >

The method for producing the steel before heat treatment preferably includes a step of pretreating carbon steel (step 1), and a step of forming a film by contacting the preparation for forming a film with ease of descaling (step 2) to the steel before heat treatment. Hereinafter, each step will be described in detail.

{2-2-1. Pretreatment Process}

Before forming the coating film on the carbon steel constituting the steel material before the heat treatment, pretreatment known in the art (for example, surface cleaning of carbon steel by degreasing or the like in advance) may be carried out.

{2-2-2. Film Formation Process}

The film forming process includes a method of forming the film by heating the surface of the carbon steel containing the metal element in a gas (for example, oxygen gas, air, etc.) containing oxygen (first method) Method The method of the present invention comprises bringing a preparation for forming a film for easy descaling into contact with a surface of a carbon steel to clean the surface of the carbon steel by the action of an etching component contained in the preparation for film formation which is easy to descale, Thereby forming a coating film. Among these, it is preferable that the coating film is uniform on the surface of the carbon steel material, and therefore, the second method is suitable from this point of view. Hereinafter, these two methods will be described in detail.

First, the heating in the first method is not particularly limited as long as it is capable of oxidizing the surface of the carbon steel including the metal element, but it is preferably carried out at 200 to 300 캜. For example, when a steel material (SCM material) having a composition of Fe-C-Cr-Mo is heated at 200 to 300 占 폚 for at least 30 minutes in an oxygen-containing gas atmosphere, an oxide film of Fe and Cr + . This oxide film is also subjected to a heat treatment at 700 DEG C or higher, thereby forming a coating film which is easy to descale.

Next, the second method is a method of contacting a surface of a carbon steel with an agent for forming a descaling-easy film containing the metal element, followed by drying, thereby forming a predetermined descaling-easy film on the surface of the carbon steel. As the contact method in the second method, for example, a dipping method, a spraying method, a roll coating method, an air spraying method, an airless spraying method, an electrolytic method (for example, a negative electrode electrolysis method) Method can be adopted. Examples of the method for removing the surplus decalcifying film-forming agent adhering to the surface of the carbon steel after contact with the film-forming agent include air knife, squeeze roll, spray water, immersion water, And it is also possible to form a descaling film on the surface of the carbon steel material efficiently in a short time by combining these with a drying process. The temperature (liquid temperature) of the film-forming preparation when the carbon steel is brought into contact with the film-forming preparation is not particularly limited, but is preferably 20 ° C to 50 ° C, more preferably 35 ° C to 45 ° C Do.

«3. Method of manufacturing steel after heat treatment by heating steel before heat treatment »

Next, a method of manufacturing a steel material after heat treatment by heating the steel material before heat treatment according to the present invention will be described. The present method can also be referred to as a scale removal method which occurs when a steel material is manufactured after a heat treatment by heating the steel material before the heat treatment.

<3-1. Heat treatment process>

The method for producing a steel material after heat treatment according to the present invention includes a step of heat-treating the steel material before the heat treatment, in which the film is formed, at 700 ° C or higher. The heat treatment temperature is preferably 700 ° C to 1350 ° C, more preferably 850 ° C to 1250 ° C, and more preferably 900 ° C to 1000 ° C. Within this range, it is possible to realize easy descaling-easy coating in the oxide scale while preventing dissolution of the steel. The heating temperature and the holding time vary depending on the steel components, the shape, the thickness, and the intended mechanical strength. For example, in order to perform the finishing treatment, the steel is heated to austenite temperature in the range of 800 to 1000 Lt; 0 &gt; C and maintaining the time of 1 to 120 minutes.

Here, the heating method to which the present invention is applied is not particularly limited, and a combination with the high frequency induction heating using the energization heating treatment and the high frequency induction heating may be employed in a heating atmosphere. In addition, laser irradiation using laser light introduced as a surface pattern of a metal is also possible.

In addition, the heat treatment to which the present invention is applied is adapted in a heat treatment that does not require a vacuum or an inert gas. Specifically, it is a heat treatment in an oxidizing atmosphere containing, for example, 1 vol% or more of oxygen. The present invention is also applicable to a hot pressing method such as a preliminary pressing method in which a heated member is pressed and molded in a metal mold, followed by rapid cooling in a metal mold.

Cooling methods and speeds also vary depending on the steel components, the shape, the thickness, and the intended mechanical strength, and examples thereof include furnace cooling, cold air cooling, water cooling, and spraying of coolant. For example, in a finishing process for obtaining martensite after a heat treatment, it is sufficient to secure a cooling rate higher than the critical cooling rate of the steel. According to another aspect of the present invention, instead of the quenching, the hot press forming may be performed using a molding die.

<3-2. Scale removal process>

The scale removal method according to the present invention includes a mechanical method such as sand blast, shot blast, wet blast, laser peening, honing and grinder, and chemical treatment methods such as phosphoric acid cleaning, sulfuric acid cleaning, hydrochloric acid cleaning, They may be combined. In this connection, it is possible to remove the scale even in the method of air blowing, water washing, etc., in which compressed air or compressed water is discharged at a discharge pressure of 0.1 MPa or more without using a projection material or abrasive.

<Examples>

«Steel»

Carbon steels having 0.03%, 0.06%, 0.1%, 0.15%, 0.3%, 0.45%, 0.77%, 3.1% and 4% by mass of carbon were used based on the total mass of carbon steel.

&Lt; Preparation of film-forming preparation &gt;

As shown in Table 1, various raw materials were added to water so as to have the blending amounts shown in Table 1, and then sufficiently stirred to obtain a film-forming preparation for the treatment liquids 1 to 102. At that time, the pH was adjusted as shown in Table 1 using acetic acid or ammonia.

&Lt; Production of steel before heat treatment &gt;

As shown in Table 2, various kinds of steels were immersed for 30 to 300 seconds in the treatment liquids (preparation for film forming) 1 to 102 controlled at 40 占 폚. The contact time (immersion time) between the various steels and the film-forming agent due to immersion was adjusted so as to obtain an adhesion amount shown in Table 2. [ Thereafter, various kinds of steel materials brought into contact with the film-forming agent were sufficiently washed with water such that the film-forming agent on the surface of the steel did not remain, drained and dried to obtain steels 1 to 132 before heat treatment.

«Manufacturing of steel after heat treatment»

Under the conditions shown in Table 2, the steels 1 to 132 before the heat treatment were heated to obtain a steel material after the heat treatment.

«Evaluation Items and Evaluation Methods»

&Lt; Appearance evaluation (ease of descale easily removability by air blow) >

(Assessment Methods)

The steel material was subjected to air blowing using an air blower after heat treatment at a discharge pressure of 5.5 KPa for 30 seconds. The scale removal area ratio of the surface of the steel material after the heat treatment was measured. Based on the following criteria, the ease of descaling was evaluated based on the following evaluation criteria. Evaluation other than x is practical performance.

(Evaluation standard)

◎: Scale removal area ratio 99% or more

○ +: Scale removal area ratio is 95% or more and less than 99%, and the background is white

○ -: The scale removal area ratio is 95% or more and less than 99%, and the background is not white (black or gray)

?: Scale removal area ratio 90% or more and less than 95%

×: Less than 90% of scale removal area ratio

&Lt; Evaluation of ease of use of ease of descaling >

(Assessment Methods)

After the formulation for easy descaling easy film formation shown in Table 1 was prepared, the appearance of the solution after 6 hours was visually observed as the presence or absence of precipitation. The change amount (%) of the total deposition amount of the metal element (Y) immediately after the preparation of the descaling-easy film-forming agent shown in Table 1 and after 24 hours after the production was determined under the film forming conditions ) Was calculated from the following formula (A). &Lt; tb &gt; &lt; TABLE &gt; Ease of descaling The ease of use of the film-forming preparation was evaluated based on the following evaluation criteria. Evaluation other than x is practical performance.

(Formula A)

(Mg / m &lt; 2 &gt;) of the metal element (Y) immediately after the preparation of the film-forming agent is adjusted. - Adjustment of the film-forming agent after 24 hours (Mg / m &lt; 2 &gt;)} / total amount of adhesion of metal element (Y) immediately after adjustment of film forming agent (mg /

(Evaluation standard)

?: No precipitate, and the change amount of the total amount of adhesion of the metal element (Y) is less than 5%

?: No precipitation, and the change amount of the total amount of adhesion of the metal element (Y) was 5% or more

DELTA: a precipitate and a change amount of the total amount of adhesion of the metal element (Y) is less than 10%

X: It is impossible to produce a steel before heat treatment because there is precipitation and the change amount of the total amount of adhesion of the metal element (Y) is not less than 10% (since the property of the liquid at 24 hours after the preparation of the film- (Including the case where it was not possible)

&Lt; Evaluation of stability at the time of applying a processing load to the preparation for film-forming ease easy scalability >

After adjusting the formulation for ease of descaling shown in Table 1, a steel material having a carbon content of 0.3% per 1,000 ml of the film-forming preparation was applied to a film-forming preparation And stored in a thermostatic chamber (at 60 DEG C for 2 hours), and then evaluated based on the following evaluation criteria. Evaluation other than x is practical performance.

⊚: Ease of descaling The surface appearance of the film-forming agent was not changed, and the change in the pH of the film-forming agent was less than 1.0

○: Ease of descaling The surface appearance of the film-forming agent was not changed, and the change in pH of the film-forming agent was 1.0 or more and less than 2.0

DELTA &lt; + &gt;: Ease of descaling The surface appearance of the film-forming agent was not changed, and the change in pH of the film-

Δ -: Ease of descaling The change in the outer appearance of the film-forming agent (with suspension and sediment) and the change in pH of the film-forming agent to less than 2.0

×: Ease of descaling The surface appearance of the film-forming agent was changed (with suspension and sediment), and the pH change of the film-forming agent was 2.0 or more

Claims (10)

In a steel before heat treatment having a coating on the surface of carbon steel,
Wherein the carbon steel contains 0.06 mass% or more of carbon based on the total mass of the carbon steel,
Wherein the film contains at least one metal element (X) selected from Fe, Ni and Co and at least one metal element (Y) selected from Ti, Zr, Hf, Nb, V, Cr, Mn, And also
The total amount of the metal element (Y) to be adhered is 1 to 100 mg /
Wherein the mass ratio (X) / (Y) of the metal element (X) to the metal element (Y) is in the range of 0.01 to 0.5. A method for manufacturing a steel product before heat treatment,
Wherein the steel before the heat treatment has a coating on the surface of the carbon steel,
Wherein the carbon steel contains 0.06 mass% or more of carbon based on the total mass of the carbon steel,
Wherein the film contains at least one metal element (X) selected from Fe, Ni and Co and at least one metal element (Y) selected from Ti, Zr, Hf, Nb, V, Cr, Mn, And also
(X) / (Y) in a mass ratio of the metal element (X) and the metal element (Y) is in the range of 0.01 to 0.5, and the total amount of the metal element (Y) is 1 to 100 mg /
The above-
(Y) selected from Ti, Zr, Hf, Nb, V, Cr, Mn, Mo and W and an etching component to the carbon steel to form the coating film Wherein the pre-heat treatment is performed at a temperature of not less than &lt; RTI ID = 0.0 &gt; In a method for producing a steel material after a heat treatment,
At least one metal element (X) selected from Fe, Ni and Co and at least one metal element selected from Ti, Zr, Hf, Nb, V, Cr, Mn, Mo and W on the surface of carbon steel containing 0.06% (X) being a mass ratio of the metal element (X) to the metal element (Y), wherein the total amount of adhesion of the metal element (Y) is 1 to 100 mg / / (Y) in the range of 0.01 to 0.5 to obtain a steel material before heat treatment,
And heat treating the steel material before the heat treatment at 700 ° C or higher. In the scale removal method,
At least one metal element (X) selected from Fe, Ni and Co and at least one metal element (Y) selected from Ti, Zr, Hf, Nb, V, Cr, Mn, Mo, To obtain a steel material before the heat treatment,
A step of heating the steel material before the heat treatment at 700 DEG C or higher to obtain a steel material after the heat treatment,
And removing the scale attached on the steel material after the heat treatment. The method according to claim 4, wherein the carbon steel contains 0.06 mass% or more of carbon, based on the total mass of the carbon steel. The method according to claim 4 or 5, wherein the total amount of adhesion of the metal element (Y) is 1 to 100 mg / m 2, and the mass ratio (X) / (Y) of the metal element (X) Is in the range of 0.01 to 0.5. A preparation for use in forming a descaling-easy film on a carbon steel constituting a steel material before the heat treatment, wherein the steel material is heated to 700 ° C or more before the heat treatment to obtain a steel material after the heat treatment,
At least one metal element (Y) selected from Ti, Zr, Hf, Nb, V, Cr, Mn, Mo and W,
Wherein the film has an etching component. The method of claim 7, wherein the descalability facilitating coating comprises at least one metal element (X) selected from Fe, Ni, and Co and at least one element selected from Ti, Zr, Hf, Nb, V, Cr, Mn, An easy-to-descale easy-to-form film-forming preparation containing at least one kind of metal element (Y). 9. The formulation for forming a descaling-easy film according to claim 7 or 8, wherein the carbon steel contains 0.06% by mass or more of carbon, based on the total mass of the carbon steel. The method according to claim 8 or 9, wherein the total amount of adhesion of the metal element (Y) is 1 to 100 mg / m 2, and the mass ratio of the metal element (X) to the metal element (Y) Is in the range of 0.01 to 0.5.