JP2013250184A - Reference substance for quantitative analysis of alloy element in steel material and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reference substance to be used for quantitative analysis of an ultra-trace alloy element or impurity content of a 10 mass ppm level in a steel material by using a physical analytical instrument having spatial resolution of 1 μm or less.SOLUTION: The reference substance is used for quantitative analysis of an ultra-trace analysis target element in the steel material by using the physical analytical instrument for performing ultra-trace element analysis in a diameter area of 0.01 to 1 μm. The reference substance is polycrystalline iron-base alloy containing predetermined mass % of the analysis target element and containing any one sort of Al: 1-10%, Si: 2-13% and Ni: 30-49%, in which the residual is composed of Fe and inevitable impurity and an average crystal grain diameter is 1 to 100 mm.

Description

  The present invention relates to a standard substance used for quantitative analysis of an extremely small amount of an element of 10 mass ppm in a steel material using a physical analysis instrument such as an electron probe microanalyzer or secondary ion mass spectrometry, and its production. Regarding the method.

  To quantitatively analyze the concentration of trace elements dissolved in the micrometer to submicrometer range in steel materials, the electron probe microanalyzer (EPMA) or secondary ion mass An analysis method (Secondary Ion Mass Spectrometry: SIMS) or the like is used. In particular, EPMA is widely used as a device for quantifying the concentration of trace elements in steel product management.

  In order to perform quantitative analysis with high accuracy in these analysis methods, prepare 3 or more standard samples with known element concentrations, create a calibration curve by plotting the relationship between signal intensity and element concentration, In general, the element concentration of the unknown sample is obtained by applying the signal intensity of the element from the sample to the calibration curve. This method is called a calibration curve method, and it is preferable that the composition of the standard substance used for preparing the calibration curve is close to the composition of the unknown sample.

  For example, in the quantitative analysis method disclosed in Patent Document 1, a calibration curve is created by an ion microanalyzer using a standard material into which an element to be quantified is ion-implanted. However, since the implanted ions have a concentration gradient from the sample surface to the inside, a calibration curve cannot be created unless the measurement method is capable of depth direction analysis. Therefore, the reference material for quantitative analysis by EPMA is required to uniformly distribute the element to be quantified in the plane direction and depth direction of the sample.

  Various standard materials for steel materials have been produced and are commercially available. Standard materials for steel materials are handled by the Japan Iron and Steel Federation, NIST in the United States, and the like, as summarized in Non-Patent Document 1, for example.

  Among them, a standard material for EPMA is distributed by the National Institute of Advanced Industrial Science and Technology as a standard material that guarantees the uniformity of components in a minute region. However, only two types of two-element iron-based alloys (Fe-C alloy, Fe-Ni alloy, Fe-Cr alloy) are prepared, and the concentration range of the additive element is also limited.

  For example, in the standard substance of the Fe-C alloy, the carbon concentration is limited to 0.01 to 0.7% in mass%, and when quantifying the carbon concentration outside this concentration range, from the range of the calibration curve Since it is off, the reliability of the quantitative result is lowered. The crystal grain size of these standard substances is about several tens of μm to several hundreds of μm.

  In addition to this, when it is desired to quantify the solid solution concentration of elements that are trace amounts and easily segregate at the grain boundaries, the concentration of solid elements in the grains decreases from the added concentration due to the presence of many trace elements at the grain boundaries. End up. In particular, this problem becomes more apparent as the particle size is smaller and the proportion of grain boundaries in the material is larger. As will be described later, when the particle size is refined to about several μm, there is a possibility that the solid solution concentration in the particles is reduced compared to the added concentration due to grain boundary segregation.

  In this case, if a physical analysis instrument having a spatial resolution of 1 μm or less is used, it is difficult to create an accurate calibration curve, and the slope of the calibration curve becomes smaller than the true slope.

  This is because when the concentration of a standard sample is guaranteed in bulk analysis such as chemical analysis, the chemical analysis value is calculated by using a physical analysis instrument having a spatial resolution of 1 μm or less, whereas the concentration of the entire sample is calculated. This is because the signal intensity obtained by randomly irradiating the standard sample with a beam requires the solid solution concentration in the grains reduced by grain boundary segregation.

  As elements that are easily segregated at grain boundaries in steel materials, for example, B, S, P, N, etc. are known, and for these elements, the preparation of a standard material that guarantees the uniformity of a minute region is described above. This is extremely difficult.

  On the other hand, in steel analysis, the addition of trace elements at the ppm level can greatly affect material properties, and there is a great need for quantitative analysis at the ppm level. For example, when 10 mass ppm of boron is added to the steel material, the hardenability of the steel material is improved and the mechanical properties of the steel material can be dramatically improved. However, boron tends to form a compound with carbon and nitrogen in the steel material, and the solid solution concentration may decrease from the amount added.

  The effect of improving hardenability by adding boron is determined by the amount of boron dissolved in the grains. Therefore, in order to control the mechanical properties of steel, not only the amount of boron but also the solid solution concentration is quantified. There is a need.

  When determining the solid solution concentration of boron, perform elemental analysis within the grain and pay close attention to the calibration curve prepared in advance, taking care not to include boron carbonitride in the analysis range. Quantify. However, due to the lack of standard materials for preparing a calibration curve, it was impossible to perform quantitative analysis.

JP-A-62-132156

Jun Ida, Yutaka Hayashibe, Bunkeki 1 (2010) 29

  The present invention has been made in view of the above problems, and the content of a trace amount of alloy elements and impurity elements at 10 ppm by mass in steel materials is quantified using a physical analysis instrument having a spatial resolution of 1 μm or less. The purpose is to provide a reference material used for analysis.

  The present inventors have intensively studied means for solving the above-mentioned problems. As a result, by adding the standard substance to a polycrystal having an average crystal grain size of 1 mm or more, or a single crystal iron-based alloy cut out from the polycrystal, an added trace element at a level of 10 ppm by mass It was found that the intra-grain solid solution concentration can be measured without being reduced by grain boundary segregation.

  This invention was made | formed based on the said knowledge, The summary is as follows.

  (1) A standard substance used for quantitative analysis of a trace amount of an element to be analyzed in a steel material using a physical analysis instrument that performs trace element analysis in a diameter range of 0.01 to 1 μm. The substance contains a predetermined amount of the element to be analyzed in mass%, and contains any one of Al: 1 to 10%, Si: 2 to 13%, and Ni: 30 to 49%, and the balance A reference material for quantitative analysis of trace elements, characterized in that is an iron-based alloy consisting of Fe and unavoidable impurities and having an average crystal grain size of 1 to 100 mm.

  (2) The standard element for quantitative analysis of trace elements according to (1) above, wherein the standard substance for quantitative analysis of trace elements is a single crystal cut out from the polycrystal.

  (3) The standard element for quantitative analysis of trace elements according to (1) or (2), wherein the physical analysis instrument is an electron beam microprobe analyzer or a secondary ion mass spectrometer.

(4) A method for preparing a standard substance used for quantitative analysis of an extremely small amount of an element to be analyzed in a steel material using a physical analysis instrument that performs a trace element analysis in a region having a diameter of 0.01 to 1 μm. ,
(I) A pure substance or molten steel of 1 to 10% of Al in terms of Al together with a compound consisting of an analysis element and Fe that can be dissolved in molten steel in a predetermined amount of pure element of the element to be analyzed in terms of element in mass% FeAl intermetallic compound that can be dissolved in Si, 2 to 13% pure substance of Si in terms of Si, or FeSi intermetallic compound that can be dissolved in molten steel, and 30 to 49% pure substance of Ni in terms of Ni Alternatively, one selected from FeNi-based intermetallic compounds that can be dissolved in molten steel is mixed with electrolytic iron, heated and dissolved in a non-oxidizing atmosphere, and then cast.
(Ii) The above slab is soaked in a non-oxidizing atmosphere between a liquidus temperature of 500 ° C. and a time of 1 minute or more and less than 45000 minutes to obtain crystal grains having an average grain size of 1 to 100 mm. A method for producing a reference material for quantitative analysis of trace elements, characterized by growing and then rapidly cooling.

  (5) The method for producing a standard material for quantitative analysis of trace elements according to (4) above, wherein a single crystal is cut out from the standard material after quenching and used as a standard material.

  (6) The method for producing a standard material for quantitative analysis of trace elements according to (4) or (5), wherein the physical analysis instrument is an electron beam microprobe analyzer or a secondary ion mass spectrometer.

  According to the present invention, it is possible to produce a uniform standard material in which concentration nonuniformity caused by grain boundary segregation of trace elements in an iron-based alloy does not occur. As a result, it is possible to perform quantitative analysis of trace elements by using a calibration curve method using a physical analysis instrument having a spatial resolution of 1 μm or less, such as EPMA and SIMS, and to elucidate metallurgical problems in manufacturing steel materials and improve materials It is possible to obtain basic knowledge on

It is a figure which shows the crystal grain size dependence of the solid solution concentration in a grain. It is a figure which shows the solid solution concentration dependence of PK (alpha) line | wire intensity by EPMA.

  The present invention is described in detail below.

  The present invention is a standard material used for quantitative analysis of the content of a trace amount of alloying elements and impurity elements at a level of 10 ppm by mass in steel materials using a physical analysis instrument having a spatial resolution of 1 μm or less, and The present invention relates to a method for producing the standard substance.

  Here, the 10 mass ppm level refers to a range of 1 to 20 mass ppm. The physical analysis equipment refers to an apparatus capable of analyzing trace elements in the micrometer or submicrometer region, such as EPMA or SIMS.

  In such a minute region, it is difficult to make the concentration distribution of the additive element in the standard material uniform. For example, in the case of a polycrystal, it is conceivable that trace elements segregate at the grain boundaries, and the solid solution concentration in the grains decreases from the added concentration. It is assumed that this problem becomes more prominent for elements that are more likely to segregate at grain boundaries. In such a case, a calibration curve representing the relationship between the signal intensity from the trace element obtained using the physical analysis instrument and the solid solution concentration cannot be accurately created. Therefore, first, the extent to which the solid solution concentration in the grains decreases due to grain boundary segregation was estimated by the following formulas (1) to (3).

  The grain size dependence of the grain boundary segregation amount of the Fe-X two-element system is expressed by the following formula (1) (K. Ishida, Journal of Alloys and Compounds, 235 (1996) 244).

ここで、ｘ^bは粒界偏析濃度（元素分率）、⁰ｘは添加元素濃度（元素分率）、ｔは粒界の厚さ、ｄは平均結晶粒径、ΔＧは粒界偏析エネルギー、Ｒは気体定数、Ｔは温度である。

Where x ^b is the grain boundary segregation concentration (element fraction), ⁰ x is the additive element concentration (element fraction), t is the grain boundary thickness, d is the average crystal grain size, ΔG is the grain boundary segregation energy, R is a gas constant and T is a temperature.

Further, when the solid solution concentration in the grain is X ^m , the volume fraction of the grain boundary in the bulk is f, and the volume fraction in the grain is (1-f), the following equation (2) is obtained.

ここで、結晶粒を球形と仮定すると、下記式（３）が得られる。

Here, assuming that the crystal grains are spherical, the following formula (3) is obtained.

粒界偏析層の厚みｔは、数原子層程度とされているので、ここでは、ｔ＝１ｎｍで計算する。また、定量分析したい元素の添加元素濃度を⁰ｘ＝１０ａｔｏｍｉｃ−ｐｐｍとする。この場合、上記式（１）〜（３）を用い、かつ、粒界偏析エネルギーΔＧ、温度Ｔを代入することで、粒内における固溶濃度の結晶粒径依存性を計算することができる。

Since the grain boundary segregation layer has a thickness t of about several atomic layers, the calculation is made here at t = 1 nm. Further, the additive element concentration of the element to be quantitatively analyzed is set to ⁰ x = 10 atomic-ppm. In this case, by using the above formulas (1) to (3) and substituting the grain boundary segregation energy ΔG and the temperature T, the dependence of the solid solution concentration in the grains on the crystal grain size can be calculated.

  The average crystal grain size dependence of the solid solution concentration calculated in this way is shown in FIG. 1 (calculated assuming ΔG = 60 kJ / mol, T = 1300 K).

  As shown in FIG. 1, it can be seen that when the average crystal grain size is small, the value of the solid solution concentration in the grain becomes small depending on the average crystal grain size. This is because when the average crystal grain size is reduced, the volume fraction of the grain boundaries in the material is increased, more additive elements are segregated at the grain boundaries, and the solid solution concentration in the grains is reduced.

  In this case, even if it is attempted to guarantee the element concentration with the chemical analysis value, the element concentration determined from the chemical analysis value (equal to the addition concentration) and the actual solid solution concentration differ from each other, creating an accurate calibration curve. Is impossible.

  From FIG. 1, it can be seen that the average crystal grain size should be about 1 mm or more in order to prevent the solid solution concentration from decreasing due to grain boundary segregation. The larger the grain boundary segregation energy ΔG, the larger the average crystal grain size necessary to prevent a decrease in the solid solution concentration.

  However, the value of ΔG is about 55 kJ / mol even in the case of elements P and S which are considered to be easily segregated (P. Lejcek and S. Hofman, Surface and Interface Analysis, 33 (2002) 203). A crystal grain size of about 1 mm is sufficient.

  The average crystal grain size may be 1 mm or more. However, when the present inventors experimented, it was not possible to produce a steel material exceeding the average crystal grain size of 100 mm with the current standard substance adjustment method.

  Here, a method for coarsening the crystal grains of the steel material will be described. In the case of pure iron, even if it is heated at a high temperature to grow and coarsen crystal grains, it undergoes a phase transformation from a face-centered cubic structure to a body-centered cubic structure in the cooling process, and the average is obtained by grain refinement by phase transformation. The crystal grain size is about several tens of μm. Therefore, when the crystal grains are coarsened to 1 mm or more, the components must be adjusted so that phase transformation in the solid phase does not occur during the heat treatment.

  For example, when Al, Si, or the like is added to Fe at a predetermined concentration, the body-centered cubic structure becomes stable over the entire temperature range in the solid phase. When Al is added, the body-centered cubic structure becomes stable at 1 to 10% by mass. When adding Si, 2-13 mass% may be sufficient.

  When Ni or the like is added to Fe at a predetermined concentration, the face-centered cubic structure becomes stable over the entire temperature range in the solid phase, but is preferably 30% by mass or more. However, if it exceeds 49% by mass, there are elements to be quantified and inevitable impurities, so the Ni concentration may exceed the Fe concentration in the composition of the standard substance. In this case, it becomes a Ni-based standard substance and is not suitable as a standard substance for quantitative analysis of trace elements in steel materials.

  For example, even if the concentration of the additive element is the same, if the base material changes, the amount of signal obtained at the time of analysis by EPMA or SIMS changes. This is because the penetration depth and escape depth of the electron beam and ions into the sample depend on the average atomic number of the base material.

  In the scope of the present invention, the concentration range of the element to be analyzed is about 10 ppm by mass, and even if combined with inevitable impurities, it does not exceed 1% by mass. It will not be a reference material.

  It is necessary that elements such as Al, Si, and Ni that are added to form a single phase within the solid phase temperature range do not form a compound in the process of preparing a standard substance with the elements that are actually quantified. When producing steel containing Al, Si, Ni, etc., for example, from electrolytic iron and pure substance of Al, Si, Ni, or any one of Al, Si, Ni that can be dissolved in molten steel and Fe A predetermined amount of the intermetallic compound is mixed and charged in a crucible, and heated to dissolve.

Examples of the intermetallic compound made of Fe and any one of Al, Si, and Ni that can be dissolved in the molten steel include Al ₂ Fe, Al ₅ Fe ₂ , FeSi, FeSi ₂ , Fe ₃ Ni, FeNi, etc. The intermetallic compound can be mentioned. When the crucible is charged, a predetermined amount of a pure substance of the analysis target element or a compound of the analysis target element that can be dissolved in molten steel and Fe are mixed together. For example, when the analysis target element is B, B alone or FeB (ferroboron) is added when the crucible is charged.

  The purity of electrolytic iron should just be 99.9 mass% or more. Preferably it is 99.99 mass% or more. For example, electrolytic iron sold by Toho Zinc Co., Ltd. may be used.

The heat melting is preferably performed in a non-oxidizing atmosphere using a rare gas such as argon gas or helium in order to prevent air from entering the molten steel. More preferred is dissolution in vacuum. The degree of vacuum may be 10 ⁻⁶ to 10 ⁴ Pa. If it exceeds 10 ⁴ Pa, there is little degassing effect due to the vacuum, and gas is released from the molten steel, so it is difficult to make it less than 10 ⁻⁶ Pa.

  In this way, when the standard material is made into a single phase in the solid phase temperature range and heated at a high temperature, crystal grain refinement due to phase transformation does not occur during cooling, and coarse crystal grains are obtained. Here, the high temperature means a temperature of 500 ° C. or higher and a liquidus temperature or lower. If it is less than 500 degreeC, since the diffusion coefficient of the additive element in iron is small, enormous time is required for the heat treatment time for crystal grain growth.

  On the other hand, when the heating temperature exceeds the liquidus temperature, a liquid phase is generated during heating, solidification segregation occurs during cooling, and a homogeneous standard material cannot be obtained.

  The heating time is preferably 1 minute or more and less than 45,000 minutes. If it is less than 1 minute, the crystal grain size does not grow to 1 mm or more depending on the heating temperature. If it is 45000 minutes or more, the heating time takes more than one month, it takes time, and even if heating is continued further, no significant change is observed in the element diffusion distance.

The high temperature heating is preferably performed in a non-oxidizing atmosphere using an inert gas, and more preferably in a reducing atmosphere, because an additive element may be taken into the oxide by surface oxidation. The reducing atmosphere is an atmosphere having an oxygen partial pressure at which iron oxide is reduced, and may be, for example, 1.8 × 10 ⁻¹¹ Pa or less at 1000 ° C.

  Such an atmosphere can be realized by adjusting the hydrogen partial pressure and the water vapor partial pressure in an atmosphere in which hydrogen and water vapor are in equilibrium as is well known. For example, hydrogen may be contained in a nitrogen atmosphere of 1 atm in a volume fraction of about 5%, and the water vapor amount may be −40 ° C. in terms of dew point.

  It is preferable to grind the surface after the heat treatment to remove the segregation layer and the contamination layer on the surface. When cooling after heating, in order to maintain element distribution at a high temperature, the cooling rate is preferably 50 to 1000 ° C./s, preferably water cooling or oil cooling, and cooling as quickly as possible. Within the scope of this study, a cooling rate exceeding 1000 ° C./s is difficult to obtain with water cooling or oil cooling.

  After the crystal grains are coarsened to 1 mm or more, they may be used as they are as standard substances, but it is preferable to cut out and use a single crystal portion. When this single crystal is divided into two and the element concentration in one single crystal is quantified by other analysis methods (chemical analysis or other instrumental analysis), the analysis value obtained includes the amount of grain boundary segregation. Therefore, only the value of the element concentration that dissolves in the grains can be obtained. After that, prepare an element whose amount to be quantified is changed by about 5 levels, analyze another single crystal by EPMA or SIMS analysis, etc., determine the signal intensity from the element, and analyze the signal intensity and analysis. If the values are plotted, a calibration curve is created and quantitative analysis is possible.

  Next, examples of the present invention will be described. The conditions in the examples are one example of conditions used for confirming the feasibility and effects of the present invention, and the present invention is based on this one example of conditions. It is not limited. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

  The example which created the calibration curve of P in Fe is shown. In order to stabilize the body-centered cubic structure of the Fe solid phase over the entire temperature range, 5% by mass of Al was mixed with 99.9% by mass of electrolytic iron, and steel added with P was vacuum-dissolved. And cast. The P concentration was set to 30 mass ppm, 80 mass ppm, 150 mass ppm, 300 mass ppm, and 500 mass ppm as target values.

  The cast steel was hot-rolled and further hot forged at 1000 ° C. After forging, it was heated to 1300 ° C. in an argon atmosphere, heat-treated for one week, and water-cooled at 300 ° C./s.

  The surface of the obtained steel material was ground and the surface segregation layer was removed.

  Further, the structure was revealed by etching, and the single crystal portion was cut out at 1 cm square. A part of the obtained single crystal was observed with a transmission electron microscope, and it was confirmed that no precipitate of P was observed in the observation region. P concentration was quantified by chemical analysis. The chemical analysis was quantified by ICP emission spectroscopic analysis according to JIS G1258-1: 2007.

  Subsequently, the single crystal was mirror-polished and subjected to EPMA analysis. Each sample was analyzed at 25 points, and the average value of the obtained X-ray intensities (PKα rays) was plotted on the vertical axis and the chemical analysis values were plotted on the horizontal axis. The results are shown in FIG. The acceleration voltage during EPMA measurement was 15 kV.

  For comparison, a calibration curve when a polycrystal (average crystal grain size: about 5 μm) is used is also shown in FIG. As shown in FIG. 2, when a polycrystal is used, the slope of the calibration curve becomes small. This is because, as described above, in the case of polycrystal, the average crystal grain size becomes small, so the volume density of the grain boundary increases, the amount of segregation at the grain boundary increases, and the solid solution concentration in the grain decreases. It is because it ends. If the P concentration of an unknown sample is quantified using this calibration curve, a value higher than the true value is calculated, so that an accurate analysis of the P concentration cannot be performed.

  Here, the slope of the calibration curve obtained with the single crystal in FIG. 2 is α, and the slope of the calibration curve obtained in the following examples is β. Considering the analysis error, it is assumed that the calibration curve is correctly created when 0.9 ≦ β / α ≦ 1.1, and whether or not the calibration curve is correctly created is determined as follows.

When β / α <0.9, 1.1 <β / α, x (not created correctly)
When 0.9 ≦ β / α ≦ 1.1, ○ (created correctly)
[Example No. 1-5]
Electrolytic iron was mixed with 0.5 to 13.0% by mass of Al, and steel with P added thereto was manufactured by vacuum melting. The Al concentration is No. 1 in Table 1. As shown in the columns 1 to 5, they are 0.5% by mass, 1.0% by mass, 5.0% by mass, 9.5% by mass, and 13.0% by mass, and the P concentration is a target value of 30%. It was set as mass ppm, 80 mass ppm, 150 mass ppm, 300 mass ppm, and 500 mass ppm.

  Subsequently, the steel was hot-rolled and hot forged at 1000 ° C. After forging, it was heated to 1300 ° C. in an argon atmosphere, heat-treated for one week, and water-cooled at 300 ° C./s.

  The surface of the obtained steel material was ground and the surface segregation layer was removed. A part of the obtained sample was observed with a transmission electron microscope, and it was confirmed that no precipitate of P was observed in the observation region. P concentration was quantified by chemical analysis. The chemical analysis was quantified by ICP emission spectroscopic analysis according to JIS G1258-1: 2007.

  The crystal grain size was determined by observation with an optical microscope when the particle size was 1 mm or less, and from an image taken with a commercially available digital camera when the particle size was more than 1 mm. The average crystal grain size obtained is shown in the column of average crystal grain size in Table 1.

  Subsequently, the sample was mirror-polished and subjected to EPMA analysis. 25 samples were analyzed per sample, and a standard curve was prepared by plotting the average value of the obtained X-ray intensities (PKα rays) on the vertical axis and the chemical analysis values on the horizontal axis. The acceleration voltage during EPMA measurement was 15 kV. The evaluation results of β / α are shown in the column of β / α in Table 1.

［実施例Ｎｏ．６〜１０］
電解鉄にＳｉを１．５〜１５．０質量％混合し、併せて、Ｐを添加した鋼を真空溶解で製造した。Ｓｉ濃度は、表２のＮｏ．６〜１０の欄に示す通り、１．５質量％、２．０質量％、５．０質量％、１３．０質量％、１５．０質量％であり、Ｐ濃度は、狙い値で、３０質量ｐｐｍ、８０質量ｐｐｍ、１５０質量ｐｐｍ、３００質量ｐｐｍ、５００質量ｐｐｍとした。

[Example No. 6-10]
A steel in which 1.5 to 15.0 mass% of Si was mixed with electrolytic iron and P was added together was manufactured by vacuum melting. The Si concentration is No. in Table 2. As shown in the columns 6 to 10, they are 1.5% by mass, 2.0% by mass, 5.0% by mass, 13.0% by mass, and 15.0% by mass, and the P concentration is a target value of 30%. It was set as mass ppm, 80 mass ppm, 150 mass ppm, 300 mass ppm, and 500 mass ppm.

  Subsequently, the steel was hot-rolled and hot forged at 1000 ° C. After forging, it was heated to 1300 ° C. in an argon atmosphere, heat-treated for one week, and water-cooled at 300 ° C./s.

  The surface of the obtained steel material was ground and the surface segregation layer was removed. A part of the obtained sample was observed with a transmission electron microscope, and it was confirmed that no precipitate of P was observed in the observation region. P concentration was quantified by chemical analysis. The chemical analysis was quantified by ICP emission spectroscopic analysis according to JIS G1258-1: 2007.

  The crystal grain size was determined by observation with an optical microscope when the particle size was 1 mm or less, and from an image taken with a commercially available digital camera when the particle size was more than 1 mm. The average crystal grain size obtained is shown in the column of average crystal grain size in Table 2.

  Subsequently, the sample was mirror-polished and subjected to EPMA analysis. 25 samples were analyzed per sample, and a calibration curve was prepared by plotting the average value of the obtained X-ray intensities (PKα rays) on the vertical axis and the chemical analysis values on the horizontal axis. The acceleration voltage during EPMA measurement was 15 kV. The evaluation results of β / α are shown in the column of β / α in Table 2.

［実施例Ｎｏ．１１〜１５］
電解鉄にＮｉを２８〜５３質量％混合し、併せて、Ｐを添加した鋼を真空溶解で製造した。Ｎｉ濃度は、表３のＮｏ．１１〜１５の欄に示す通り、２８質量％、３０質量％、３９質量％、４８質量％、５３質量％であり、Ｐ濃度は、狙い値で、３０質量ｐｐｍ、８０質量ｐｐｍ、１５０質量ｐｐｍ、３００質量ｐｐｍ、５００質量ｐｐｍとした。

[Example No. 11-15]
Electrolytic iron was mixed with 28 to 53 mass% of Ni, and steel with P added thereto was manufactured by vacuum melting. The Ni concentration is the same as that in Table 3. As shown in the columns 11 to 15, they are 28 mass%, 30 mass%, 39 mass%, 48 mass%, 53 mass%, and the P concentration is a target value, 30 mass ppm, 80 mass ppm, 150 mass ppm. 300 mass ppm and 500 mass ppm.

  Subsequently, the steel was hot-rolled and hot forged at 1000 ° C. After forging, it was heated to 1300 ° C. in an argon atmosphere, heat-treated for one week, and water-cooled at 300 ° C./s.

  The surface of the obtained steel material was ground and the surface segregation layer was removed. A part of the obtained sample was observed with a transmission electron microscope, and it was confirmed that no precipitate of P was observed in the observation region. P concentration was quantified by chemical analysis. The chemical analysis was quantified by ICP emission spectroscopic analysis according to JIS G1258-1: 2007.

  The crystal grain size was determined by observation with an optical microscope when the particle size was 1 mm or less, and from an image taken with a commercially available digital camera when the particle size was more than 1 mm. The average crystal grain size obtained is shown in the column of average crystal grain size in Table 3.

  Subsequently, the sample was mirror-polished and subjected to EPMA analysis. 25 samples were analyzed per sample, and a standard curve was prepared by plotting the average value of the obtained X-ray intensities (PKα rays) on the vertical axis and the chemical analysis values on the horizontal axis. The acceleration voltage during EPMA measurement was 15 kV. The evaluation results of β / α are shown in the column of β / α in Table 3.

［実施例Ｎｏ．１６〜２０］
電解鉄にＡｌを０．５〜１３．０質量％混合し、併せて、Ｐを添加した鋼を真空溶解で製造した。Ａｌ濃度は、表４のＮｏ．１６〜２０の欄に示す通り、０．５質量％、１．０質量％、５．０質量％、９．５質量％、１３．０質量％であり、Ｐ濃度は、狙い値で、３０質量ｐｐｍ、８０質量ｐｐｍ、１５０質量ｐｐｍ、３００質量ｐｐｍ、５００質量ｐｐｍとした。

[Example No. 16-20]
Electrolytic iron was mixed with 0.5 to 13.0% by mass of Al, and steel with P added thereto was manufactured by vacuum melting. The Al concentration is No. in Table 4. As shown in the column of 16-20, it is 0.5 mass%, 1.0 mass%, 5.0 mass%, 9.5 mass%, 13.0 mass%, P concentration is a target value, 30 It was set as mass ppm, 80 mass ppm, 150 mass ppm, 300 mass ppm, and 500 mass ppm.

  Subsequently, the steel was hot-rolled and hot forged at 1000 ° C. After forging, it was heated to 1300 ° C. in an argon atmosphere, heat-treated for one week, and water-cooled at 300 ° C./s.

  The surface of the obtained steel material was ground and the surface segregation layer was removed. A part of the obtained sample was observed with a transmission electron microscope, and it was confirmed that no precipitate of P was observed in the observation region. Subsequently, no. 16 and No. No. 20 About 17-19, the single crystal part of the sample was cut out using the cutting machine (Corporation | KK Maruto, crystal cutter MC413). P concentration was quantified by chemical analysis. The chemical analysis was quantified by ICP emission spectroscopic analysis according to JIS G1258-1: 2007.

  Subsequently, the single crystal sample was mirror-polished and subjected to EPMA analysis. 25 samples were analyzed per sample, and a standard curve was prepared by plotting the average value of the obtained X-ray intensities (PKα rays) on the vertical axis and the chemical analysis values on the horizontal axis. The acceleration voltage during EPMA measurement was 15 kV. The evaluation results of β / α are shown in the column of β / α in Table 4.

［実施例Ｎｏ．２１〜２５］
電解鉄にＳｉを１．５〜１５．０質量％混合し、併せて、Ｐを添加した鋼を真空溶解で製造した。Ｓｉ濃度は、表５のＮｏ．２１〜２５の欄に示す通り、１．５質量％、２．０質量％、５．０質量％、１３．０質量％、１５．０質量％であり、Ｐ濃度は、狙い値で、３０質量ｐｐｍ、８０質量ｐｐｍ、１５０質量ｐｐｍ、３００質量ｐｐｍ、５００質量ｐｐｍとした。

[Example No. 21-25]
A steel in which 1.5 to 15.0 mass% of Si was mixed with electrolytic iron and P was added together was manufactured by vacuum melting. The Si concentration is No. in Table 5. As shown in the columns 21 to 25, they are 1.5% by mass, 2.0% by mass, 5.0% by mass, 13.0% by mass, 15.0% by mass, and the P concentration is a target value, 30 It was set as mass ppm, 80 mass ppm, 150 mass ppm, 300 mass ppm, and 500 mass ppm.

  Subsequently, the steel was hot-rolled and hot forged at 1000 ° C. After forging, it was heated to 1300 ° C. in an argon atmosphere, heat-treated for one week, and water-cooled at 300 ° C./s.

  The surface of the obtained steel material was ground and the surface segregation layer was removed. A part of the obtained sample was observed with a transmission electron microscope, and it was confirmed that no precipitate of P was observed in the observation region. Subsequently, no. 21 and no. No. 25, no. About 22-24, the single crystal part of the sample was cut out using the cutting machine (Corporation | KK Maruto, crystal cutter MC413). However, only a single crystal region could not be cut out from a polycrystalline body having an average crystal grain size of less than 1 mm using a cutting machine.

  P concentration was quantified by chemical analysis. The chemical analysis was quantified by ICP emission spectroscopic analysis according to JIS G1258-1: 2007.

  Subsequently, the single crystal sample was mirror-polished and subjected to EPMA analysis. 25 points were analyzed per sample, and the average value of the obtained X-ray intensities (PKα rays) was plotted on the vertical axis and the chemical analysis values were plotted on the horizontal axis to prepare a calibration curve. The acceleration voltage during EPMA measurement was 15 kV. The evaluation results of β / α are shown in the column of β / α in Table 5.

［実施例Ｎｏ．２６〜３０］
電解鉄にＮｉを２８〜５３質量％混合し、併せて、Ｐを添加した鋼を真空溶解で製造した。Ｎｉ濃度は、表６のＮｏ．２６〜３０の欄に示す通り、２８質量％、３０質量％、３９質量％、４８質量％、５３質量％であり、Ｐ濃度は、狙い値で、３０質量ｐｐｍ、８０質量ｐｐｍ、１５０質量ｐｐｍ、３００質量ｐｐｍ、５００質量ｐｐｍとした。

[Example No. 26-30]
Electrolytic iron was mixed with 28 to 53 mass% of Ni, and steel with P added thereto was manufactured by vacuum melting. The Ni concentration is No. in Table 6. As shown in the column of 26-30, they are 28 mass%, 30 mass%, 39 mass%, 48 mass%, 53 mass%, and P concentration is a target value, 30 mass ppm, 80 mass ppm, 150 mass ppm. 300 mass ppm and 500 mass ppm.

  Subsequently, the steel was hot-rolled and hot forged at 1000 ° C. After forging, it was heated to 1300 ° C. in an argon atmosphere, heat-treated for one week, and water-cooled at 300 ° C./s.

  The surface of the obtained steel material was ground and the surface segregation layer was removed. A part of the obtained sample was observed with a transmission electron microscope, and it was confirmed that no precipitate of P was observed in the observation region.

  Subsequently, no. 26 and no. No. 30 except for No. 30. About 27-29, the single crystal part of the sample was cut out using the cutting machine (Corporation | KK Maruto, crystal cutter MC413). P concentration was quantified by chemical analysis. The chemical analysis was quantified by ICP emission spectroscopic analysis according to JIS G1258-1: 2007.

  Subsequently, the sample was mirror-polished and subjected to EPMA analysis. 25 samples were analyzed per sample, and a standard curve was prepared by plotting the average value of the obtained X-ray intensities (PKα rays) on the vertical axis and the chemical analysis values on the horizontal axis. The acceleration voltage during EPMA measurement was 15 kV. The evaluation results of β / α are shown in the column of β / α in Table 6.

以上、表１の実施例のＮｏ２〜４に示す通り、Ａｌ添加量が１〜１０質量％の範囲内では、平均結晶粒径が１ｍｍ以上に粗大化することが可能で、検量線が正しく作成されて、正確な定量分析が可能となる。

As described above, as shown in Nos. 2 to 4 of Examples in Table 1, when the Al addition amount is in the range of 1 to 10% by mass, the average crystal grain size can be coarsened to 1 mm or more, and the calibration curve is created correctly. Thus, accurate quantitative analysis becomes possible.

  Similarly, as shown in Nos. 7 to 15 of the examples in Table 2, if the Si addition amount is in the range of 2 to 13% by mass or the Ni addition amount is in the range of 30 to 49%, the average crystal grain size Can be coarsened to 1 mm or more, a calibration curve is created correctly, and accurate quantitative analysis is possible.

  A single crystal is obtained by cutting out crystal grains in a coarsened polycrystal, but if the average crystal grain size is not more than 1 mm, the single crystal portion cannot be cut out using a cutting machine. On the other hand, if the added amount of Al, Si, Ni is within the above-mentioned concentration range, the average crystal grain size becomes 1 mm or more, and it is possible to cut out a single crystal part. Can be created.

  According to the present invention, it is possible to produce a uniform standard material in which concentration nonuniformity caused by grain boundary segregation of trace elements in an iron-based alloy does not occur. As a result, it is possible to perform quantitative analysis of trace elements by using a calibration curve method using a physical analysis instrument having a spatial resolution of 1 μm or less, such as EPMA and SIMS, and to elucidate metallurgical problems in manufacturing steel materials and improve materials It is possible to obtain basic knowledge on Therefore, the present invention has high applicability in the steel industry.

Claims (6)

  A standard substance used to quantitatively analyze an extremely small amount of an element to be analyzed in a steel material using a physical analysis instrument that performs trace element analysis in a region having a diameter of 0.01 to 1 μm. In addition to containing a predetermined amount of the element to be analyzed in mass%, Al: 1 to 10%, Si: 2 to 13%, and Ni: 30 to 49%, the balance being Fe and A standard substance for quantitative analysis of trace elements, characterized in that it is an iron-based alloy that is an inevitable impurity and is a polycrystal having an average crystal grain size of 1 to 100 mm.   2. The standard element for quantitative analysis of trace elements according to claim 1, wherein the standard substance for quantitative analysis of trace elements is a single crystal cut out from the polycrystal.   The standard substance for quantitative analysis of trace elements according to claim 1 or 2, wherein the physical analysis instrument is an electron beam microprobe analyzer or a secondary ion mass spectrometer. A method for preparing a standard substance used for quantitative analysis of an extremely small amount of an analysis target element in a steel material using a physical analysis instrument that performs trace element analysis in a region having a diameter of 0.01 to 1 μm,
(I) 1% to 10% pure Al material or molten steel in terms of Al, with a mass% of a predetermined amount of pure elemental material in terms of element or a compound composed of an analytical element soluble in molten steel and Fe FeAl intermetallic compound that can be dissolved in Si, 2 to 13% pure substance of Si in terms of Si, or FeSi intermetallic compound that can be dissolved in molten steel, and 30 to 49% pure substance of Ni in terms of Ni Alternatively, one selected from FeNi-based intermetallic compounds that can be dissolved in molten steel is mixed with electrolytic iron, heated and dissolved in a non-oxidizing atmosphere, and then cast.
(Ii) The above slab is soaked in a non-oxidizing atmosphere between a liquidus temperature of 500 ° C. and a time of 1 minute or more and less than 45,000 minutes to obtain crystal grains having an average crystal grain size of 1 to 100 mm. A method for producing a reference material for quantitative analysis of trace elements, characterized by growing and then rapidly cooling.   The method for producing a standard material for quantitative analysis of trace elements according to claim 4, wherein a single crystal is cut out from the standard material after quenching and used as a standard material.   The method for producing a standard substance for quantitative analysis of trace elements according to claim 4 or 5, wherein the physical analysis instrument is an electron beam microprobe analyzer or a secondary ion mass spectrometer.

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