63 results about "Elemental analysis" patented technology

The invention discloses a polluted river water nitrogen and phosphorus removal efficiency evaluation system and method based on element analysis, and relates to the technical field of sewage treatment evaluation. An algae growth dynamic model is trained, and the future growth dynamic state of algae is obtained according to future water body data and future environment driving data; the method comprises the following steps: analyzing the interference influence of interference ion concentration on sensor measurement according to future water body data, dynamically simulating the attachment rate and biofilm thickness of algae on the surface of a sensor probe according to future growth of the algae, analyzing the attachment influence of the algae on sensor measurement, and correcting the measurement precision of the sensor according to the interference influence and the attachment influence. According to the corrected sensor data, whether the nitrogen and phosphorus removal efficiency of the polluted river water meets the removal standard or not is evaluated, real-time correction of the sensor data is achieved through interference ion concentration analysis and dynamic simulation of biological adhesion influence, and the accuracy of monitoring data and the scientificity of pollution treatment efficiency evaluation are effectively improved.

The invention relates to the technical field of spectral analysis, and particularly discloses an underwater intelligent detection machine system and method based on laser-induced breakdown spectroscopy, and the system comprises an underwater carrying platform, an orthogonal double-pulse laser-induced breakdown spectroscopy probe, a multi-sensor cooperative sensing module, a mechanical arm, a central control unit and a water surface control station. The method comprises the following steps: a first pulse vertically builds bubbles, and a second pulse parallelly enters the bubbles and is triggered according to delay time; the central control unit maintains a working distance of 1-2cm based on a distance measurement closed loop, and adaptively adjusts delay time and energy in combination with water depth pressure and cavitation feedback; and the water surface control station carries out denoising normalization on the spectrum calibration and carries out element qualitative and quantitative operation to generate an element distribution atlas. According to the method, plasma is excited in a cavitation bubble gas environment through orthogonal double pulses, and in-situ real-time high-sensitivity element detection of an underwater target is realized in combination with distance closed loop and parameter self-adaption.

This application relates to the field of conveyor belt fire technology, and provides a method and system for assessing the fire hazard of conveyor belts based on surface elemental analysis. In this method, the degradation degree index of the target conveyor belt is calculated by analyzing the changes in the content of surface constituent elements over wear time. Once the degradation degree index passes reliability verification, a constructed degradation-combustion prediction model is used to calculate the fire risk index of the target conveyor belt over wear time. This avoids interference from environmental factors such as underground dust and humidity in traditional assessment methods, enabling full life-cycle assessment and diagnosis of conveyor belts under different wear states before a fire occurs, overcoming the lag in traditional early warning methods.

Reference materials with increased lithium content for direct elemental analyses, wherein the glass contains 55 to 75 wt.% SiO2, 7 to 15 wt.% Na2O, 6 to 15 wt.% CaO, up to 3.5 wt.% AI2O3, up to 3.5 wt.% K2O, and up to 12 wt.% Li2O, and the value of the relative standard deviation (RSD) of homogeneous element distribution in the glass, determined by inductively coupled plasma mass spectrometry combined with laser ablation (LA-ICP-MS), is less than or equal to 5%.

The present invention relates to a process for binding carbon dioxide to a waste building material 10, wherein the reaction is carried out in a carbonation reactor 20, wherein a waste building material 10 is fed to the carbonation reactor 20, wherein a carbon dioxide-containing gas 30 is fed to the carbonation reactor 20, and wherein a carbonation product 50 is discharged from the carbonation reactor 20, characterized in that the alkaline earth content of the waste building material 10 fed to the carbonation reactor 20 and / or of the carbonation product 50 discharged from the carbonation reactor 20 is determined by means of elemental analysis 60, wherein the degree of carbonation C of the carbonation product 50 is determined by IR spectroscopy, and wherein a carbonation degree limit value Cmax is set.wherein if the carbonation degree limit Cmax is undershot, the supply of the waste material 10 to the carbonation reactor 20 is reduced and / or the supply of the carbon dioxide-containing gas 30 to the carbonation reactor 20 is increased, wherein if the carbonation degree limit Cmax is exceeded, the supply of the waste material 10 to the carbonation reactor 20 is increased and / or the supply of the carbon dioxide-containing gas 30 to the carbonation reactor 20 is reduced.

The present invention provides a method for selecting an inorganic filler, which can select an inorganic filler suitable for use in combination with a silane coupling agent using a functional group present on the filler surface as an index, and a method for producing a surface-treated inorganic filler and a method for producing a composite material using the selected inorganic filler. [Solution] The method for selecting an inorganic filler is a method for selecting an inorganic filler having a hydroxyl group, and includes the steps of: reacting the inorganic filler having a hydroxyl group with a trimethylsilylating agent to obtain an inorganic filler having a trimethylsilyl group; measuring the carbon concentration in the inorganic filler having a trimethylsilyl group by elemental analysis and calculating the concentration A of trimethylsilylated hydroxyl groups in the inorganic filler having a trimethylsilyl group based on the carbon concentration; and selecting an inorganic filler having a hydroxyl group based on the hydroxyl group concentration A.

1. Name of the product in this design: Elemental Analyzer. 2. Application of this design: It is used for measuring the carbon, hydrogen, and nitrogen content in solid and liquid samples (including urea) in fields such as power, coal, metallurgy, petrochemicals, coal chemicals, environmental protection, cement, papermaking, geological exploration, scientific research institutes, and solid and hazardous waste. 3. The key design feature of this product is its shape. 4. The picture or photo that best illustrates the key design points: Design 1 3D diagram 1. 5. Design 1 is designated as the basic design.

The utility model discloses a kind of crucible replacement devices, including lifting datum plate, translation datum plate and crucible seat, sample sending sealing seat is equipped on the crucible seat, sample sending sealing seat is equipped on the sample sending rod, the top of the sample sending rod is equipped with the load-bearing platform for carrying crucible, the crucible seat is moved and arranged on translation datum plate along horizontal direction, translation datum plate is moved and arranged on lifting datum plate along vertical direction, and the lifting datum plate is used to be fixedly connected with the high-temperature furnace of elemental analyzer.The utility model further discloses a kind of elemental analyzer.The utility model has the advantages of simple structure and low failure rate.

In order to enable a dust filter to be replaced appropriately, irrespective of the skill level of a user, provided is a filter unit which is provided on a lead-out flow path through which a mixed gas composed of a carrier gas and a sample gas is led out from a heating furnace, the filter unit comprising: a filter element that collects dust in the mixed gas; an upstream-side holder and a downstream-side holder that face each other with the filter element interposed therebetween; and a fixing mechanism that fixes the filter element in a state where the upstream-side holder and the downstream-side holder hold the filter element therebetween. The fixing mechanism has an engaged part provided to either the upstream-side holder or the downstream-side holder, and a hook part that is provided to the other of the upstream-side holder and the downstream-side holder and that engages with the engaged part. The fixing mechanism fixes the upstream-side holder and the downstream-side holder by causing the hook part to engage with the engaged part.

The invention relates to a sample pretreatment method for chromite microelement analysis. The method comprises the following steps: firstly, treating a sample to specific particle size distribution (Dv (50) lt, 5 [mu] m, Dv (90) lt, 20 [mu] m) through physical accurate grinding, and then adopting an improved two-step acid dissolution and digestion process: firstly, destroying main crystal lattices of minerals by using mixed acid, then, carrying out targeted dissolution on a residual insoluble phase by using aqua regia, and finally, carrying out chlorine removal treatment to obtain a solution to be detected. Through the synergistic effect of physical accurate grinding and secondary acid dissolution, almost complete decomposition of chromite is achieved, especially the extraction efficiency of key indissolvable elements such as Sc and Zn is improved by 20% or above, the accuracy and precision of ICP-MS analysis results are remarkably improved, and the problem that microelement measured value systematicness is low due to incomplete dissolution in a traditional method is solved.

The application relates to a high gravity-microwave assisted concentration device for water solution element analysis, which comprises an inner cavity, an outer cavity, a heat exchanger and a condensed liquid storage tank; a microwave generator is arranged in the inner cavity, an air inlet is arranged on the side wall, a flow guide plate is fixed on the inner side wall and can be rotated around the fixed shaft as the center, the microwave generator is arranged on the upper wall of the inner cavity and is close to the upper wall, a concentrated liquid discharge port is arranged at the bottom of the inner cavity, the outer cavity is fixed on the outer side of the inner cavity and completely wraps the inner cavity to form a sealed environment, a gap of 4cm-15cm is arranged between the outer cavity and the inner cavity, an inert gas pipeline connected with inert gas is fixed on the top of the outer cavity, and the bottom is connected with the concentrated liquid storage tank; one end of the heat exchanger is connected with the feeding port, the other end is connected with high-temperature steam of volatile liquid separated from the mixed fluid, and the bottom is connected with the condensed liquid storage tank. The device can shorten the concentration time and improve the concentration efficiency.

The invention discloses an element analyzer reaction tube automatic cleaning and filling instrument, and particularly relates to the technical field of reaction tube automatic cleaning and filling, the element analyzer reaction tube automatic cleaning and filling instrument comprises an operation table, a reaction tube cleaning station and a reaction tube filling station which are arranged above the operation table, and a waste bin arranged below an operation table frame, the weighing sensor is arranged in the reaction tube cleaning station, the pressure sensor is arranged in the reaction tube filling station, and the vacuum pump is arranged in the waste bin; the weighing sensor and the pressure sensor are connected with a control module through signals, and the control module controls the power load rate of the vacuum pump according to the residue weight, detected by the weighing sensor, of the inner wall of the reaction tube and whether the pressure sensor detects the bottom surface pressure increase of the vibration table or not. Cleanness control over the reaction tube cleaning and filling process is achieved, and therefore the reaction tube cleaning effect and the reaction tube filling precision are ensured.

The invention discloses a method for identifying the producing area of saffron crocus by extracting saffron crocus aldehyde and measuring the stable isotope ratio of the saffron crocus aldehyde. The invention discloses a method for extracting crocetin from saffron crocus and measuring the stable isotope ratio of carbon to hydrogen to oxygen. The method comprises the following steps: S1, determining the stable isotope ratio of carbon to hydrogen to oxygen of a crocetin standard substance by using an elemental analysis-stable isotope mass spectrometer; s2, extracting crocus sativus aldehyde from the crocus sativus sample to obtain a crocus sativus aldehyde extracting solution; s3, determining the carbon, hydrogen and oxygen stable isotope ratio of crocetin in the crocetin extracting solution by using a gas chromatography-stable isotope mass spectrometer; and S4, calibrating the carbon, hydrogen and oxygen stable isotope ratio of crocetin in the crocetin extracting solution by adopting the carbon, hydrogen and oxygen stable isotope ratio of the crocetin standard substance. The standard substance is used for calibrating the stable isotope ratio of carbon, hydrogen and oxygen of the single compound crocetin, and the method can be used for identifying the producing area of crocetin.

The invention relates to a method for analyzing carbon content in a liquid biological sample and a carbon content element analyzer. The method comprises the following steps: unfreezing the biological sample to a liquid state; transferring the biological sample into a glove box; a tin cup is taken to be heated, and the tin cup is put into a glove box after being heated; a biological sample is taken and placed in a tin cup, and the mass of the biological sample in the tin cup is weighed; sealing the opening of the tin cup; the tin cup is moved to a sample disc of an element analyzer, the biological sample is subjected to high-temperature oxidation in the element analyzer to generate corresponding gas, the gas is dried and then subjected to carbon content analysis, the carbon content in the biological sample is obtained, and in the drying process, the mixture is adopted as a drying agent for drying. The drying tube is arranged in the elemental analyzer, the drying agent is optimized, the sample quality is controlled, the influence of moisture on carbon content analysis is reduced, the sample does not need pretreatment such as freeze-drying, and the sample pretreatment time is saved.

The invention discloses a gem and jade output and mineralization condition analysis method, and relates to the technical field of mineral exploration and mineral spectroscopy analysis. The method comprises the following steps: grading and sampling primary ore and secondary ore; performing high-pressure closed digestion and element analysis to obtain the content of a target element; calculating chemical mineralization indexes, establishing a spectrum and diffraction spectrum library, and extracting a characteristic peak area ratio as a spectroscopic standard variable; acquiring a cathode luminescence image and a spectrum and determining an intensity ratio; integrating a chemical metallogenic index, a spectroscopic standard variable, a cathode luminescence intensity ratio and a regional geological variable into a target feature vector, and modeling based on a machine learning model and an interpretation algorithm to obtain a metallogenic analysis model; and outputting a mineralization probability index and performing grading judgment according to a threshold value. According to the method, through multi-source geology-geochemistry-spectroscopy information fusion and machine learning modeling, the accuracy and efficiency of gem and jade metallogenic condition recognition and prospective area / target area judgment are improved.

This invention discloses a method for constructing a macromolecular model of Hami oil-rich coal and its application. The molecular formula and functional group characteristics of the coal sample are determined through elemental analysis and infrared spectroscopy. A planar structural model is constructed using the Wiser model framework, and a stable configuration is obtained after geometric optimization. Finally, a pyrolysis reaction model containing multiple molecules is constructed through stacking. Targeting the high-oxygen and high-cycloalkane structural characteristics of Hami oil-rich coal, a C1... 128 H 82 NO 16 and C 111 H 88 NO 28 Two precise models were used, and the accuracy of the calculated infrared spectra was verified by comparing them with experimental spectra. ReaxFF molecular dynamics simulations were performed using this model, revealing the influence of different heating rates and pyrolysis temperatures on product distribution. The optimal simulation temperature and critical values ​​for pyrolysis rate control were determined, and the difference in ethylene formation pathways between alkyl-rich coal and ether-rich coal was analyzed. This invention fills the gap in precise models for Hami oil-rich coal, providing key theoretical basis and parameter guidance for optimizing pyrolysis processes, achieving targeted regulation, and improving energy efficiency.

The invention relates to a sample pretreatment method for pyrite elemental analysis. The method comprises the following steps: firstly, preparing a pretreatment agent: activating the surface of carboxymethyl chitosan by NHS / EDC, and then reacting with ethanolamine phosphate; secondly, a pyrite sample is taken and smashed into particles, the particles, NaOH, NaNO3 and a pretreatment agent are fully ground into powder, then the temperature is increased to 180-250 DEG C and then increased to 350-450 DEG C for heat preservation, sintered solids are transferred into a beaker, a hot nitric acid solution is added, the solids are dissolved through ultrasonic treatment, the solids are filtered into a volumetric flask after being cooled, and a to-be-tested sample is obtained after the volume is fixed through dilute nitric acid; according to the treatment method, use of a large amount of concentrated acid and perchloric acid is avoided, the reagent dosage is small, and environment friendliness is achieved; the recovery rate of 95% or above can be ensured when the treated sample is measured by instruments such as ICP-MS, the maximum RSD value does not exceed 5% compared with a standard value, and the accuracy is good.

The invention discloses a method for rapidly evaluating the stability of a soil organic carbon library. The method comprises the following steps: firstly, carrying out standard pretreatment on a soil sample; carrying out particle size grading on the pretreated standardized sample through a physical method, separating out organic carbon components fPOM, cPOM and MAOM, respectively collecting each component and removing inorganic carbon in each component; all the components are dried and ground; standard sample packaging is conducted on all the components, the components are sent into an element analyzer to be detected and analyzed, and the organic carbon content measured by all the components is obtained; calculating the stability index of the organic carbon library, and evaluating the stability. According to the method, a quantitative carbon library stability evaluation model is constructed, the operation is simple, the cost is low, a closed loop is formed by separation-detection-evaluation, and a powerful technical tool is provided for rapid and accurate evaluation of the soil carbon sink function under the carbon neutralization background.

This invention relates to a hydride generation gaseous sample introduction method and apparatus for heavy metal element determination in conjunction with a liquid cathode glow discharge-atomic emission spectrometer, belonging to the field of atomic spectroscopy metal element analysis technology. This invention uses chemically generated carbon dioxide gas as a carrier gas, which is then used as the atmosphere gas in the liquid cathode glow discharge to ionize and generate micro-plasma. The chemical hydride generation method converts the applicable analyte element into a hydride, which is then carried into the micro-plasma by the carbon dioxide carrier gas, atomized, and excited to generate an emission spectrum.

The utility model discloses an instrument for quantitatively calibrating active functional groups of humic acid and fulvic acid, which relates to the technical field of chemical component analysis and comprises an element analyzer, two test bottles are arranged in the element analyzer, the right surface of the element analyzer is fixedly connected with a fixed block, the upper surface of the fixed block is movably clamped with a connecting block, and the upper surface of the connecting block is fixedly connected with the element analyzer. A connecting frame is fixedly connected to the upper surface of a connecting block, two limiting blocks connected to the lead screw in a sleeving mode move relatively under the action of threads by rotating the lead screw, the two limiting blocks drive fixed clamping plates to move together in the relative moving process, and at the moment, the two clamping plates can clamp and fix a test bottle; the sample is accurately located at the optimal position detected by an instrument, stable conditions of a detection light path, electrode contact and the like are ensured, accurate positions of an image spectrum analysis element analyzer and a test bottle can ensure that a light source accurately irradiates the sample, a detector can receive stable and accurate spectrum signals, and accurate analysis of related elements of active functional groups is facilitated.

The application relates to a sample pretreatment method for pyrite element analysis. First, a pretreatment agent is prepared: carboxymethyl chitosan is activated on the surface through NHS / EDC, and then reacts with phosphoethanolamine to obtain the pretreatment agent; secondly, a pyrite sample is crushed into particles, and is fully ground into powder together with NaOH, NaNO3 and the pretreatment agent; then, the temperature is increased to 180-250 DEG C and then to 350-450 DEG C for heat preservation; the sintered solid is transferred into a beaker, hot nitric acid solution is added, ultrasonic is used to dissolve the solid, and after cooling, filtration is carried out into a volumetric flask, and dilute nitric acid is used for constant volume to obtain a sample to be tested. The treatment method avoids the use of a large amount of concentrated acid and perchloric acid, the reagent consumption is small, and the method is environment-friendly; the treated sample is determined by an ICP-MS instrument and the like, and the recovery rate can be ensured to be above 95%; compared with a standard value, the RSD value is not more than 5%, and the accuracy is good.

Disclosed is a surface-treated steel sheet containing Ti and Al, and having improved post-paint corrosion resistance. The surface-treated steel sheet of this disclosure comprises a base steel sheet and a chemical conversion coating disposed on the surface of the base steel sheet. The chemical composition of the base steel sheet is, by mass%, Ti: 0.050 to 1.000% and Al: 0.050 to 2.000%. When elemental analysis of the surface-treated steel sheet of this disclosure is performed from the surface in the thickness direction by glow discharge emission spectrometry, the following relationships are satisfied: 1.1 ≤ I1 / I2 ≤ 20.0 and 1.1 ≤ I3 / I4 ≤ 5.0 (I1: maximum emission intensity for N in the chemical conversion coating, I2: average emission intensity for N in the base steel sheet, I3: maximum emission intensity for Ti in the chemical conversion coating, I4: average emission intensity for Ti in the base steel sheet).

The present invention relates to a method for binding carbon dioxide to an old construction material (10), wherein: the reaction is carried out in a carbonation reactor (20); an old construction material (10) is supplied to the carbonation reactor (20); a carbon-dioxide-containing gas (30) is supplied to the carbonation reactor (20); a carbonation product (50) is discharged from the carbonation reactor (20), characterised in that the alkaline earth content of the old construction material (10) supplied to the carbonation reactor (20) and / or of the carbonation product (50) discharged from the carbonation reactor (20) is determined by means of elemental analysis (60), wherein: the degree of carbonation C of the carbonation product (50) is determined by IR spectroscopy; a degree-of-carbonation limit value Cmax is defined; if the degree-of-carbonation limit value Cmax is not reached, the supply of the old construction material (10) to the carbonation reactor (20) is reduced and / or the supply of the carbon-dioxide-containing gas (30) to the carbonation reactor (20) is increased, wherein, if the degree-of-carbonation limit value Cmax is exceeded, the supply of the old construction material (10) to the carbonation reactor (20) is increased and / or the supply of the carbon-dioxide-containing gas (30) to the carbonation reactor (20) is reduced.

A catalyst includes a catalytically active material; and a support including: a carbon-containing material including at least one of graphene and graphite, wherein the carbon-containing material includes less than 5 wt. % oxygen based on elemental analysis of the carbon-containing material; and at least one of cerium oxide and praseodymium oxide.

The method comprises the following steps: (1) taking a plurality of samples from a target stratum, carrying out element analysis, mineral content analysis and total organic carbon content analysis on each sample, and respectively obtaining correlation coefficients R of the mineral content and the total organic carbon content with each element content; (2) respectively selecting sensitive elements of the mineral content and the total organic carbon content according to the correlation coefficient R, and respectively establishing a change relation model (I), P = a + sigma (bi * Ei), (I), between the mineral content and the total organic carbon content and the corresponding sensitive element content; and (3) sampling while drilling from the target stratum, obtaining the content of each sensitive element, determining the mineral content and the total organic carbon content through the formula (I), and determining the type of the lithofacies of the target stratum. The method can accurately and rapidly identify the shale oil stratum lithofacies, has the advantages of low cost, simple operation and high timeliness, and is wide in application range.

This invention discloses a NOx control method for a chain grate rotary kiln based on multi-source fuel utilization. This method, targeting different levels of environmental warnings and ultra-low emission requirements, first establishes a solid fuel combustion characteristic database including anthracite, bituminous coal, and their blends based on industrial analysis, elemental analysis, and thermogravimetric experiments. Simultaneously, it employs CFD numerical simulation technology, coupling an Eulerian-Lagrange multiphase flow model and a P-1 radiation model, to analyze the flow field and NOx formation patterns under pulverized coal and natural gas co-firing conditions. Upon receiving control commands, it calculates the inlet concentration threshold based on the real-time efficiency of the denitrification system, intelligently recommends the optimal fuel ratio using the multi-source database, and outputs corresponding kiln tail temperature, combustion air volume, and raw material structure control parameters. This invention, through a dual approach of "experimentation + simulation," achieves the suppression of fuel-type and thermal NOx formation at the source, meeting differentiated environmental indicators while ensuring stable production.

A device for coal rock recognition while drilling is disclosed. The device includes an elemental analyzer arranged on a drill pipe. A coal rock recognition information monitoring panel is connected to the elemental analyzer by a data cable. A circuit board is arranged in the elemental analyzer and a processor mounted on the circuit board. A detection head is connected to the circuit board and arranged on a side wall of the elemental analyzer. The detection head includes a detector and an X-ray tube.

The invention discloses a method for determining the content of organic sulfur in hydrocarbon source rock, and belongs to the technical field of oil-gas exploration and development. According to the method, the organic sulfur content in the hydrocarbon source rock organic matter is calculated by adopting a method of combining total rock X-ray diffraction analysis and total sulfur analysis. The method comprises the following steps: firstly, obtaining an X-ray diffraction pattern based on a total rock X-ray diffraction test, carrying out phase analysis to obtain mineral composition in a hydrocarbon source rock powder sample, then quantitatively analyzing the mass percent of the sulfur-containing mineral in the hydrocarbon source rock powder sample according to a characteristic peak in the sulfur-containing mineral in the X-ray diffraction pattern, and further obtaining the inorganic sulfur content of the hydrocarbon source rock powder sample. Meanwhile, the total sulfur content of the hydrocarbon source rock powder sample is obtained through an element analysis experiment, and the difference value of the total sulfur content and the inorganic sulfur content in the sample serves as the organic sulfur content. According to the analysis method, kerogen does not need to be prepared, chemical reagents are not used in the whole process, the experiment process is shortened, operation is easy, safety and convenience are achieved, test data are stable and reliable, and repeatability is high.

The present application relates to the technical fields of elemental analysis instrument, and discloses an integrated sulfur-nitrogen-chlorine elemental analysis instrument based on a decomposition control mechanism, which comprises an analysis instrument body, a detector and a decomposition control mechanism arranged in the analysis instrument body; the decomposition control mechanism comprises a sample loading assembly, a flow guiding and gas supplying assembly, a control assembly, a lifting and guiding assembly and a gas guiding assembly. The control assembly drives the sample to rotate circumferentially under the driving of the driving assembly and to move axially reciprocatingly under the guidance of the lifting and guiding assembly, so as to drive the sample to continuously roll, tilt and displace; the sample loading assembly is provided with a shaking and dispersing assembly for periodically shaking and dispersing the sample; and the gas guiding assembly is used for conveying the decomposition generated gas to the detector for analysis and detection. The present application can improve the heating uniformity of the block sample in the decomposition process, reduce the sample accumulation and caking, and improve the accuracy and stability of the sulfur, nitrogen and chlorine element detection.

A hot-rolled steel sheet has, as its chemical composition, in % by mass: C: 0.01% to 0.30%; Si: 0.01% to 3.00%; Mn: 0.20% to 3.00%; P: 0.030% or less; S: 0.030% or less; Al: 0.001% to 2.000%; N: 0.0100% or less; and Ni: 0.02% to 0.50%, wherein among the measurement points where elemental analysis is performed in a 1 µm measurement step using an EPMA in a 250 µm × 250 µm region on a surface, the percentage of measurement points having a Ni content of 0.5% by mass or more is 10% to 70%.