JP2012108003A - METHOD FOR MEASURING CARBURIZED DEPTH OF Cr-CONTAINING ALLOY - Google Patents
METHOD FOR MEASURING CARBURIZED DEPTH OF Cr-CONTAINING ALLOY Download PDFInfo
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本発明は、例えばボイラや焼却炉等の材料に用いられるＣｒ含有合金の表層の浸炭深さを測定する方法に関する。 The present invention relates to a method for measuring the carburization depth of a surface layer of a Cr-containing alloy used for materials such as boilers and incinerators.
クロムを含有する合金（以下、「Ｃｒ含有合金」という。）は、耐熱性、耐食性、耐摩耗性等の性質に優れるため、種々の産業で利用されている。例えば、耐食性に優れるオーステナイト系のステンレス鋼（ニッケルクロム鋼）は、ボイラの伝熱管や焼却炉の材料に用いられる。 Alloys containing chromium (hereinafter referred to as “Cr-containing alloys”) are excellent in properties such as heat resistance, corrosion resistance, and wear resistance, and thus are used in various industries. For example, austenitic stainless steel (nickel chrome steel) having excellent corrosion resistance is used as a material for boiler heat transfer tubes and incinerators.
ところで、回収ボイラや焼却炉は、未燃カーボンや炭素化合物（例えばＣａＣＯ３）等が存在する高温環境下で運転されるため、浸炭が発生する。浸炭とは未燃カーボンや炭素化合物に含まれる炭素がＣｒ含有合金内へ拡散して粒界に炭化物を形成する現象である。浸炭発生の結果、粒界近傍のクロム濃度が減少することで、同部位の耐食性が損なわれるため塩化腐食などの腐食が著しく増大してしまう。そこで、Ｃｒ含有合金の浸炭の程度つまりは耐食性の程度を把握するために、回収ボイラや焼却炉等の表層における浸炭深さを測定する必要がある。 By the way, since the recovery boiler and the incinerator are operated in a high temperature environment where unburned carbon, a carbon compound (for example, CaCO 3 ) and the like are present, carburization occurs. Carburization is a phenomenon in which unburned carbon or carbon contained in a carbon compound diffuses into a Cr-containing alloy to form carbides at grain boundaries. As a result of carburization, the chromium concentration in the vicinity of the grain boundary decreases, and the corrosion resistance of the same part is impaired, so that corrosion such as chloride corrosion significantly increases. Therefore, in order to grasp the degree of carburization of the Cr-containing alloy, that is, the degree of corrosion resistance, it is necessary to measure the carburization depth in the surface layer of a recovery boiler, an incinerator or the like.
従来、Ｃｒ含有合金の表層における浸炭深さの測定は、測定対象物を切断して試料を作製して断面組織を観察したり、測定対象物の表面組織をフィルムに転写して表面組織を観察したりすることで行われていた。しかし、前者の手法は、測定対象物の破壊（接断）を伴うため採用できない場合がある。また、後者の手法は、浸炭の有無を判別できるものの、浸炭深さを定量的に把握することはできない。
なお、これらの手法とは別に、回収ボイラや焼却炉の燃料性状や、測定対象物への付着物の分析結果から浸炭の発生を推察することもあるが、あくまで推察であり、実際に浸炭が発生しているかを正確に知ることはできない。
Conventionally, the measurement of carburization depth on the surface layer of Cr-containing alloy is performed by cutting the measurement object to produce a sample and observing the cross-sectional structure, or transferring the surface structure of the measurement object to the film and observing the surface structure It was done by doing. However, the former method may not be adopted because it involves destruction (connection) of the measurement object. Moreover, although the latter method can determine the presence or absence of carburization, the carburization depth cannot be grasped quantitatively.
In addition to these methods, carburization may be inferred from the fuel properties of the recovery boiler and incinerator and the analysis results of the deposits on the measurement object. It is not possible to know exactly what has happened.
したがって、測定対象物を破壊することなく、浸炭深さを定量的に把握しうる測定手法の開発が望まれていた。
この点、特許文献１には、発光分光分析により、熱処理後の鋼材の表層における脱炭層や浸炭層等の分析を行う方法が記載されている。この方法は、表層の深さ方向における主要元素の連続的な濃度分布を得るために、試料表面の削れ深さと放電時間との関係を予め取得しておき、この関係に基づいて、発光分光分析で連続的に測定した発光強度から任意の深さにおける主要元素の濃度を求めるというものである。特許文献１に記載された方法によれば、測定対象物を破壊することなく、浸炭深さを定量的に把握することができる。
Therefore, it has been desired to develop a measurement method capable of quantitatively grasping the carburization depth without destroying the measurement object.
In this regard, Patent Document 1 describes a method of analyzing a decarburized layer, a carburized layer, and the like in the surface layer of the steel material after heat treatment by emission spectroscopic analysis. In this method, in order to obtain a continuous concentration distribution of main elements in the depth direction of the surface layer, the relationship between the shaving depth of the sample surface and the discharge time is acquired in advance, and emission spectroscopy analysis is performed based on this relationship. The concentration of the main element at an arbitrary depth is obtained from the luminescence intensity continuously measured in (1). According to the method described in Patent Document 1, it is possible to quantitatively grasp the carburization depth without destroying the measurement object.
しかしながら、特許文献１に記載された方法は、測定対象物の表層の元素をアーク放電により励起して発光させ、この発光を分光することで分析を行うものであるから、アーク放電のための電源及びケーブルが必要である。このため、ケーブルの取り回しができない等の理由により、簡易に測定できない場合がある。 However, since the method described in Patent Document 1 performs analysis by exciting elements on the surface layer of a measurement object by arc discharge to emit light and analyzing the emitted light, a power source for arc discharge is used. And cables are required. For this reason, there are cases where the measurement cannot be performed simply because the cable cannot be routed.
本発明は、上述の事情に鑑みてなされたものであり、簡易な測定が可能であり、かつ、測定対象物を破壊することなく、浸炭深さを定量的に把握しうるＣｒ含有合金の浸炭深さ測定方法を提供することを目的とする。 The present invention has been made in view of the circumstances described above, and carburization of a Cr-containing alloy that allows simple measurement and can quantitatively grasp the carburization depth without destroying the measurement object. An object is to provide a depth measurement method.
本発明に係るＣｒ含有合金の浸炭深さ測定方法は、主成分であるベース金属元素に対して、少なくともクロム及びクロム以外の金属元素が添加されてなるＣｒ含有合金の表層における浸炭深さを測定する方法であって、浸炭深さが異なるＣｒ含有合金の複数の試料についてポータブル型蛍光Ｘ線分析装置により分析を行って、クロム及びクロム以外の金属元素の濃度と浸炭深さとの関係を予め求めておき、測定対象物であるＣｒ含有合金について前記ポータブル型蛍光Ｘ線分析装置により分析を行って、該測定対象物中のクロム及びクロム以外の金属元素の濃度を測定し、予め求めた前記関係に基づいて、前記測定対象物中のクロム及びクロム以外の金属元素の濃度の測定結果から、前記測定対象物の浸炭深さを求めることを特徴とする。 The method for measuring the carburization depth of a Cr-containing alloy according to the present invention measures the carburization depth in the surface layer of a Cr-containing alloy obtained by adding at least chromium and a metal element other than chromium to the base metal element as the main component. A plurality of Cr-containing alloy samples having different carburization depths are analyzed by a portable X-ray fluorescence spectrometer, and the relationship between the concentration of chromium and metal elements other than chromium and the carburization depth is obtained in advance. The Cr-containing alloy as the measurement object is analyzed by the portable fluorescent X-ray analyzer, and the concentrations of chromium and metal elements other than chromium in the measurement object are measured, and the relationship obtained in advance is determined. The carburization depth of the measurement object is obtained from the measurement results of the concentrations of chromium and metal elements other than chromium in the measurement object.
本願発明者は、主成分であるベース金属元素に対してクロム及びクロム以外の金属元素が添加されてなるＣｒ含有合金について蛍光Ｘ線分析法による分析を行うと、Ｃｒ含有合金の表層における浸炭深さによって、クロム及びクロム以外の金属元素の濃度の測定結果に違いが出ることを見出した。本願発明者は、この知見に基づいて、上記浸炭深さ測定方法を着想した。 The inventor of the present application analyzed the Cr-containing alloy obtained by adding chromium and a metal element other than chromium to the base metal element as a main component, and analyzed the depth of carburization in the surface layer of the Cr-containing alloy. Thus, it was found that the measurement results of the concentrations of chromium and metal elements other than chromium differ. The inventor of the present application has conceived the carburization depth measurement method based on this finding.
上記浸炭深さ測定方法によれば、ポータブル型蛍光Ｘ線分析装置を用いて、測定対象物を破壊することなく測定を行うことができる。
また、予め取得したクロム及びクロム以外の金属元素の濃度と浸炭深さとの関係に基づいて、測定対象物中のクロム及びクロム以外の金属元素の濃度の測定結果から浸炭深さを求めるようにしたので、浸炭深さを定量的に把握できる。しかも、Ｃｒ濃度に加えてクロム以外の金属元素の濃度という２つのパラメータを用いて浸炭深さを求めるようにしたので、浸炭深さを高精度に算出できる。
さらに、持ち運び可能なポータブル型蛍光Ｘ線分析装置を用いるため、現地でも簡易かつ迅速に測定を行うことができる。
According to the carburization depth measurement method, measurement can be performed using the portable fluorescent X-ray analyzer without destroying the measurement object.
In addition, based on the relationship between the concentration of chromium and metal elements other than chromium and the carburization depth acquired in advance, the carburization depth is obtained from the measurement results of the concentrations of chromium and metal elements other than chromium in the measurement object. Therefore, the carburization depth can be grasped quantitatively. In addition, since the carburization depth is obtained using two parameters of the concentration of the metal element other than chromium in addition to the Cr concentration, the carburization depth can be calculated with high accuracy.
Furthermore, since a portable X-ray fluorescence analyzer that can be carried is used, measurements can be performed easily and quickly even on site.
上記浸炭深さ測定方法において、前記クロム以外の金属元素はニッケル又はモリブデンであってもよい。また、前記Ｃｒ含有合金はニッケルクロム鋼であってもよい。 In the carburization depth measurement method, the metal element other than chromium may be nickel or molybdenum. The Cr-containing alloy may be nickel chrome steel.
上記浸炭深さ測定方法において、前記測定対象物は回収ボイラの伝熱管であってもよい。
回収ボイラの伝熱管にはＣｒ含有合金を用いることが多いが、回収ボイラの伝熱管は未燃カーボンや炭素化合物（例えばＣａＣＯ３）等が存在する高温環境下に曝されるため、浸炭による粒界のクロム濃度の減少によってＣｒ含有合金の耐食性が損なわれやすい。この点、上記浸炭深さ測定方法は、伝熱管を切断することなく、伝熱管を構成するＣｒ含有合金の表層における浸炭深さを簡易に測定することができるから、回収ボイラの伝熱管のＣｒ含有合金の耐食性を管理するために有用である。
In the carburization depth measurement method, the measurement object may be a heat transfer tube of a recovery boiler.
Although a Cr-containing alloy is often used for the heat transfer tube of the recovery boiler, the heat transfer tube of the recovery boiler is exposed to a high temperature environment in which unburned carbon, carbon compounds (for example, CaCO 3 ) and the like are present, so The corrosion resistance of the Cr-containing alloy is likely to be impaired due to the decrease in the chromium concentration in the boundary. In this respect, the above carburized depth measurement method can easily measure the carburized depth in the surface layer of the Cr-containing alloy constituting the heat transfer tube without cutting the heat transfer tube, so the Cr of the heat transfer tube of the recovery boiler It is useful for managing the corrosion resistance of the alloy containing.
本発明によれば、蛍光Ｘ線分析法を用いて、測定対象物を破壊することなく測定を行うことができる。
また、予め取得したクロム及びクロム以外の金属元素の濃度と浸炭深さとの関係に基づいて、測定対象物中のクロム及びクロム以外の金属元素の濃度の測定結果から浸炭深さを求めるようにしたので、浸炭深さを定量的に把握できる。しかも、Ｃｒ濃度に加えてクロム以外の金属元素の濃度という２つのパラメータを用いて浸炭深さを求めるようにしたので、浸炭深さを高精度に算出できる。
さらに、持ち運び可能なポータブル型蛍光Ｘ線分析装置を用いるため、現地でも簡易かつ迅速に測定を行うことができる。
According to the present invention, measurement can be performed using a fluorescent X-ray analysis method without destroying an object to be measured.
In addition, based on the relationship between the concentration of chromium and metal elements other than chromium and the carburization depth acquired in advance, the carburization depth is obtained from the measurement results of the concentrations of chromium and metal elements other than chromium in the measurement object. Therefore, the carburization depth can be grasped quantitatively. In addition, since the carburization depth is obtained using two parameters of the concentration of the metal element other than chromium in addition to the Cr concentration, the carburization depth can be calculated with high accuracy.
Furthermore, since a portable X-ray fluorescence analyzer that can be carried is used, measurements can be performed easily and quickly even on site.
［浸炭深さが蛍光Ｘ線分析結果に与える影響］
本願発明者は、主成分であるベース金属元素に対してクロム及びクロム以外の金属元素が添加されてなるＣｒ含有合金について蛍光Ｘ線分析法による分析を行うと、Ｃｒ含有合金の表層における浸炭深さによって、クロム及びクロム以外の金属元素の濃度の測定結果に違いが出ることを見出した。
図１は、蛍光Ｘ線分析法によるニッケルクロム鋼（ＳＵＳ３０４）の成分分析結果を示す表である。同図に示すように、浸炭が発生していない場合、ＳＵＳ３０４の成分規格範囲内の数値を示すが、浸炭が発生すると、Ｃｒ濃度が減少し、Ｎｉ濃度が増大する。これは、蛍光Ｘ線分析法では、浸炭によって炭化物になったクロムが検出されずＣｒ濃度が見かけ上減少し、その分だけＮｉ濃度が見かけ上増大したためと考えられる。なお、含有量が最も多いベース金属元素である鉄は、浸炭の有無による影響がほとんどない。
本願発明者は、この知見に基づいて、本発明に係る浸炭深さ測定方法を着想した。
[Effect of carburization depth on fluorescent X-ray analysis results]
The inventor of the present application analyzed the Cr-containing alloy obtained by adding chromium and a metal element other than chromium to the base metal element as a main component, and analyzed the depth of carburization in the surface layer of the Cr-containing alloy. Thus, it was found that the measurement results of the concentrations of chromium and metal elements other than chromium differ.
FIG. 1 is a table showing the component analysis results of nickel chrome steel (SUS304) by fluorescent X-ray analysis. As shown in the figure, when carburization has not occurred, a numerical value within the component specification range of SUS304 is shown, but when carburization occurs, the Cr concentration decreases and the Ni concentration increases. This is presumably because, in the X-ray fluorescence analysis, chromium that became carbide by carburization was not detected, the Cr concentration apparently decreased, and the Ni concentration apparently increased by that amount. Note that iron, which is the base metal element with the largest content, has almost no effect due to the presence or absence of carburization.
Based on this finding, the inventor of the present application has conceived the carburization depth measurement method according to the present invention.
［第１実施形態］
以下、本発明の第１実施形態に係る浸炭深さ測定方法について説明する。本実施形態では、測定対象物は、Ｃｒ濃度が１８％であり、Ｎｉ濃度が８％のニッケルクロム鋼（ＳＵＳ３０４）からなるＣｒ含有合金である。
[First Embodiment]
Hereinafter, the carburization depth measurement method according to the first embodiment of the present invention will be described. In this embodiment, the measurement object is a Cr-containing alloy made of nickel chromium steel (SUS304) having a Cr concentration of 18% and a Ni concentration of 8%.
図２は、本実施形態に係るＣｒ含有合金の表層における浸炭深さの測定方法を示すフローチャートである。同図に示すように、最初に、浸炭深さが異なる複数の試料片（試料１〜３）について、ポータブル型蛍光Ｘ線分析装置を用いて分析を行う（ステップＳ２）。
ここで用いるポータブル型蛍光Ｘ線分析装置は、持ち運び可能であり、好ましくはケーブルレスである。例えば、ポータブル型蛍光Ｘ線分析装置として、サーモフィッシャーサイエンティフィック社製のＸＬ３ｔシリーズ（ＸＬ３ｔ−８００，ＸＬ３ｔ−８００Ｓ，ＸＬ３ｔ−９００Ｓ−Ａ）を用いることができる。
FIG. 2 is a flowchart showing a method for measuring the carburization depth in the surface layer of the Cr-containing alloy according to this embodiment. As shown in the figure, first, a plurality of sample pieces (samples 1 to 3) having different carburization depths are analyzed using a portable fluorescent X-ray analyzer (step S2).
The portable fluorescent X-ray analyzer used here is portable and preferably cableless. For example, XL3t series (XL3t-800, XL3t-800S, XL3t-900S-A) manufactured by Thermo Fisher Scientific can be used as a portable X-ray fluorescence analyzer.
試料１〜３は、いずれも測定対象物と同種のＣｒ含有合金、すなわちニッケルクロム鋼（ＳＵＳ３０４：Ｃｒ濃度；１８％、Ｎｉ濃度；８％）である。各試料片の浸炭深さは、各試料片の断面組織の観察により予め測定されており、既知である。本実施形態では、試料１は浸炭が発生していない（すなわち、浸炭深さゼロ）のに対し、試料２及３は浸炭が発生しており、試料２よりも試料３のほうが浸炭深さは深い。
Samples 1 to 3 are all Cr-containing alloys of the same type as the object to be measured, that is, nickel chromium steel (SUS304: Cr concentration; 18%, Ni concentration; 8%). The carburization depth of each sample piece is measured in advance by observing the cross-sectional structure of each sample piece and is known. In the present embodiment, sample 1 has no carburization (that is, carburization depth is zero), while
次に、ステップＳ２の測定結果から、上記ニッケルクロム鋼の浸炭深さと、ポータブル蛍光Ｘ線分析装置により測定されたＣｒ濃度及びＮｉ濃度との関係を求める（ステップＳ４）。具体的には、測定された試料１〜３のＣｒ濃度及びＮｉ濃度に対して各試料片の浸炭深さをプロットし、最小二乗法等の公知の手法により近似曲線を求める。
なお、ステップＳ４においてＣｒ濃度及びＮｉ濃度と浸炭深さとの関係を求めるのは、浸炭の影響が出やすい添加金属元素（クロム及びニッケル）の濃度をパラメータとすることで、浸炭深さの測定を高精度に行うことができるからである。仮にＦｅ濃度をパラメータとして用いると、ベース金属元素である鉄は浸炭の有無による影響をほとんど受けないため（図１参照）、浸炭深さの測定を高精度に行うことが難しい。
Next, the relationship between the carburizing depth of the nickel chrome steel and the Cr concentration and Ni concentration measured by the portable X-ray fluorescence analyzer is obtained from the measurement result of step S2 (step S4). Specifically, the carburizing depth of each sample piece is plotted against the measured Cr concentration and Ni concentration of samples 1 to 3, and an approximate curve is obtained by a known method such as the least square method.
In step S4, the relationship between the Cr concentration and the Ni concentration and the carburization depth is obtained by measuring the carburization depth by using the concentration of the additive metal elements (chromium and nickel) that are easily affected by carburization as parameters. This is because it can be performed with high accuracy. If the Fe concentration is used as a parameter, iron as the base metal element is hardly affected by the presence or absence of carburization (see FIG. 1), and therefore it is difficult to measure the carburization depth with high accuracy.
図３は、ニッケルクロム鋼におけるＣｒ濃度及びＮｉ濃度と浸炭深さとの関係を示すグラフである。なお、同図に示す近似曲線１０は、試料１〜３の各座標の近似曲線である。
図３に示すように、浸炭が発生していない試料１は、Ｃｒ濃度が約１８％であり、Ｎｉ濃度が約８％であって、いずれも成分規格範囲内の数値を示す。一方、浸炭が発生している試料２及び３は、Ｃｒ濃度が１８％よりも低く、Ｎｉ濃度は８％よりも多くなっている。これは、蛍光Ｘ線分析法では、浸炭によって炭化物になったクロムが検出されずＣｒ濃度が見かけ上減少し、その分だけＮｉ濃度が見かけ上増大したためと考えられる。
FIG. 3 is a graph showing the relationship between Cr concentration and Ni concentration and carburization depth in nickel chromium steel. In addition, the
As shown in FIG. 3, the sample 1 in which carburization did not occur has a Cr concentration of about 18% and a Ni concentration of about 8%, both of which are numerical values within the component specification range. On the other hand,
続いて、図２に示すように、上記ポータブル蛍光Ｘ線分析装置を用いて測定対象物（ニッケルクロム鋼）の分析を行って、測定対象物のＣｒ濃度及びＮｉ濃度を測定する（ステップＳ６）。
なお、測定対象物は、回収ボイラの伝熱管であってもよい。回収ボイラの伝熱管のように、未燃カーボンや炭素化合物（例えばＣａＣＯ３）等が存在する高温環境下に曝されるものは、粒界腐食によるクロムの減少によってＣｒ含有合金の耐食性が損なわれやすい。この点、本実施形態の浸炭深さ測定方法は、伝熱管を切断することなく、伝熱管を構成するＣｒ含有合金の表層における浸炭深さを簡易に測定することができるから、回収ボイラの伝熱管のＣｒ含有合金の耐食性を管理するために有用である。
Subsequently, as shown in FIG. 2, the measurement object (nickel chrome steel) is analyzed using the portable fluorescent X-ray analyzer, and the Cr concentration and the Ni concentration of the measurement object are measured (step S6). .
Note that the measurement object may be a heat transfer tube of a recovery boiler. When exposed to high-temperature environments where unburned carbon or carbon compounds (for example, CaCO 3 ) exist, such as heat transfer tubes of recovery boilers, the corrosion resistance of Cr-containing alloys is impaired by the reduction of chromium due to intergranular corrosion. Cheap. In this respect, the carburization depth measurement method of the present embodiment can easily measure the carburization depth in the surface layer of the Cr-containing alloy constituting the heat transfer tube without cutting the heat transfer tube. This is useful for managing the corrosion resistance of the Cr-containing alloy of the heat tube.
最後に、ステップＳ４で求めたニッケルクロム鋼におけるＣｒ濃度及びＮｉ濃度と浸炭深さとの関係に基づいて、ステップＳ６で測定された測定対象物（ニッケルクロム鋼）のＣｒ濃度及びＮｉ濃度から、測定対象物の表層における浸炭深さを求める（ステップＳ８）。例えば、ステップＳ６で測定された測定対象物のＣｒ濃度及びＮｉ濃度を近似曲線１０に代入して、測定対象物の表層における浸炭深さを求めてもよい。
Finally, based on the relationship between the Cr concentration and Ni concentration in the nickel chrome steel obtained in step S4 and the carburization depth, the measurement is performed from the Cr concentration and Ni concentration of the measurement object (nickel chrome steel) measured in step S6. The carburization depth in the surface layer of the object is obtained (step S8). For example, the carburization depth in the surface layer of the measurement object may be obtained by substituting the Cr concentration and Ni concentration of the measurement object measured in step S6 into the
以上説明したように、本実施形態では、主成分である鉄に対してクロム及びニッケルが添加されたニッケルクロム鋼からなり、浸炭深さが異なる試料１〜３についてポータブル型蛍光Ｘ線分析装置により分析を行って、Ｃｒ濃度及びＮｉ濃度と浸炭深さとの関係を予め求めておき、ニッケルクロム鋼からなる測定対象物についてポータブル型蛍光Ｘ線分析装置により分析を行って、該測定対象物中のＣｒ濃度及びＮｉ濃度を測定し、予め求めたＣｒ濃度及びＮｉ濃度と浸炭深さとの関係に基づいて、Ｃｒ濃度及びＮｉ濃度の測定結果から測定対象物の表層における浸炭深さを求める。 As described above, in the present embodiment, samples 1 to 3 made of nickel chromium steel in which chromium and nickel are added to iron as a main component and having different carburization depths are measured by a portable fluorescent X-ray analyzer. Analyze, the relationship between the Cr concentration and Ni concentration and the carburization depth is obtained in advance, and the measurement object made of nickel chrome steel is analyzed by a portable fluorescent X-ray analyzer. The Cr concentration and the Ni concentration are measured, and the carburization depth in the surface layer of the measurement object is obtained from the measurement result of the Cr concentration and the Ni concentration based on the relationship between the Cr concentration and the Ni concentration obtained in advance and the carburization depth.
本実施形態によれば、蛍光Ｘ線分析法を用いて、測定対象物を破壊することなく測定を行うことができる。
また、予め取得したＣｒ濃度及びＮｉ濃度と浸炭深さとの関係に基づいて、測定対象物中のＣｒ濃度及びＮｉ濃度の測定結果から浸炭深さを求めるようにしたので、浸炭深さを定量的に把握できる。しかも、Ｃｒ濃度に加えてＮｉ濃度という２つのパラメータを用いて浸炭深さを求めるようにしたので、浸炭深さを高精度に算出できる。
さらに、持ち運び可能なポータブル型蛍光Ｘ線分析装置を用いるため、現地でも簡易かつ迅速に測定を行うことができる。
According to the present embodiment, measurement can be performed using a fluorescent X-ray analysis method without destroying the measurement object.
Further, since the carburization depth is obtained from the measurement results of the Cr concentration and the Ni concentration in the measurement object based on the relationship between the Cr concentration and Ni concentration acquired in advance and the carburization depth, the carburization depth is quantitatively determined. Can grasp. In addition, since the carburization depth is obtained using two parameters of Ni concentration in addition to Cr concentration, the carburization depth can be calculated with high accuracy.
Furthermore, since a portable X-ray fluorescence analyzer that can be carried is used, measurements can be performed easily and quickly even on site.
［第２実施形態］
次に、第２実施形態に係るＣｒ含有合金の表層における浸炭深さの測定方法について説明する。本実施形態は、測定対象物であるＣｒ含有合金が、Ｃｒ濃度が１８％、Ｍｏ濃度が２％のクロムモリブデン鋼（ＳＵＳ３１６）を用いる点を除けば、第１実施形態の測定方法と共通する。したがって、ここでは第１実施形態と異なる点を中心に説明する。
[Second Embodiment]
Next, a method for measuring the carburization depth in the surface layer of the Cr-containing alloy according to the second embodiment will be described. This embodiment is common to the measurement method of the first embodiment, except that the Cr-containing alloy as the measurement object uses chromium molybdenum steel (SUS316) having a Cr concentration of 18% and a Mo concentration of 2%. . Therefore, here, the description will focus on the differences from the first embodiment.
本実施形態で用いる試料片（試料４〜６）は、いずれも測定対象物と同種のＣｒ含有合金、すなわちクロムモリブデン鋼（Ｃｒ濃度：１８％、Ｍｏ濃度：２％）である。各試料片の浸炭深さは、各試料片の断面組織の観察により予め測定されており、既知である。試料４は浸炭が発生していない（すなわち、浸炭深さゼロ）のに対し、試料５及６は浸炭が発生しており、試料５よりも試料６のほうが浸炭深さは深い。
なお、クロムモリブデン鋼は、クロムだけでなくモリブデンも炭化物を形成する。すなわち、本実施形態でＣｒ含有合金として用いるクロムモリブデン鋼は、クロム及びモリブデンの両方が炭化されて粒界腐食されうる点で、第１実施形態でＣｒ含有合金として用いたニッケルクロム鋼と異なる（ニッケルクロム鋼の場合、クロムのみが炭化物を形成し、ニッケルは炭化物を形成しない）。
The sample pieces (samples 4 to 6) used in this embodiment are all Cr-containing alloys of the same type as the measurement object, that is, chromium molybdenum steel (Cr concentration: 18%, Mo concentration: 2%). The carburization depth of each sample piece is measured in advance by observing the cross-sectional structure of each sample piece and is known. Sample 4 has no carburization (that is, carburization depth is zero), while samples 5 and 6 have carburization, and sample 6 has a deeper carburization depth than sample 5.
Note that chromium molybdenum steel forms carbides not only with chromium but also with molybdenum. That is, the chromium molybdenum steel used as the Cr-containing alloy in this embodiment is different from the nickel chromium steel used as the Cr-containing alloy in the first embodiment in that both chromium and molybdenum can be carbonized to cause intergranular corrosion ( In the case of nickel-chrome steel, only chromium forms carbides, nickel does not form carbides).
本実施形態では、主成分である鉄に対してクロム及びモリブデンが添加されたクロムモリブデン鋼からなり、浸炭深さが異なる試料４〜６について、ポータブル型蛍光Ｘ線分析装置を用いて分析を行って、Ｃｒ濃度及びＭｏ濃度と浸炭深さとの関係を予め求めておき、クロムモリブデン鋼からなる測定対象物についてポータブル型蛍光Ｘ線分析装置により分析を行って、該測定対象物中のＣｒ濃度及びＭｏ濃度を測定し、予め求めたＣｒ濃度及びＭｏ濃度と浸炭深さとの関係に基づいて、Ｃｒ濃度及びＭｏ濃度の測定結果から測定対象物の表層における浸炭深さを求める。 In the present embodiment, samples 4 to 6 made of chromium molybdenum steel in which chromium and molybdenum are added to iron as a main component and having different carburization depths are analyzed using a portable X-ray fluorescence analyzer. Then, the relationship between the Cr concentration and the Mo concentration and the carburization depth is obtained in advance, the measurement object made of chromium molybdenum steel is analyzed by a portable X-ray fluorescence analyzer, and the Cr concentration and The Mo concentration is measured, and the carburization depth in the surface layer of the measurement object is obtained from the measurement results of the Cr concentration and the Mo concentration based on the relationship between the Cr concentration and the Mo concentration and the carburization depth obtained in advance.
図４は、クロムモリブデン鋼におけるＣｒ濃度及びＭｏ濃度と浸炭深さとの関係を示すグラフである。なお、同図に示す近似曲線２０は、試料４〜６の各座標の近似曲線である。
図４に示すように、浸炭が発生していない試料４は、Ｃｒ濃度が約１８％であり、Ｍｏ濃度が約２％であって、いずれも成分規格範囲内の数値を示す。一方、浸炭が発生している試料５及び６は、Ｃｒ濃度が１８％よりも低く、Ｎｉ濃度も２％よりも低い。これは、蛍光Ｘ線分析法では、浸炭によって炭化物になったクロム及びモリブデンが検出されずＣｒ濃度とＭｏ濃度の両方が見かけ上減少したためと考えられる。
FIG. 4 is a graph showing the relationship between Cr concentration and Mo concentration and carburization depth in chromium molybdenum steel. The
As shown in FIG. 4, Sample 4 in which carburization has not occurred has a Cr concentration of about 18% and a Mo concentration of about 2%, both of which show numerical values within the component specification range. On the other hand, Samples 5 and 6 in which carburization has occurred have a Cr concentration lower than 18% and a Ni concentration lower than 2%. This is presumably because, in the X-ray fluorescence analysis, chromium and molybdenum that became carbide by carburization were not detected, and both the Cr concentration and the Mo concentration apparently decreased.
本実施形態によれば、上述の第１実施形態と同様に、蛍光Ｘ線分析法を用いて、測定対象物を破壊することなく測定を行うことができる。
また、予め取得したＣｒ濃度及びＭｏ濃度と浸炭深さとの関係に基づいて、測定対象物中のＣｒ濃度及びＭｏ濃度の測定結果から浸炭深さを求めるようにしたので、浸炭深さを定量的に把握できる。しかも、Ｃｒ濃度に加えてＭｏ濃度という２つのパラメータを用いて浸炭深さを求めるようにしたので、浸炭深さを高精度に算出できる。
さらに、持ち運び可能なポータブル型蛍光Ｘ線分析装置を用いるため、現地でも簡易かつ迅速に測定を行うことができる。
According to the present embodiment, similarly to the first embodiment described above, measurement can be performed using a fluorescent X-ray analysis method without destroying the measurement object.
Further, since the carburization depth is obtained from the measurement result of the Cr concentration and the Mo concentration in the measurement object based on the relationship between the Cr concentration and the Mo concentration acquired in advance and the carburization depth, the carburization depth is quantitatively determined. Can grasp. In addition, since the carburization depth is obtained using two parameters of Mo concentration in addition to Cr concentration, the carburization depth can be calculated with high accuracy.
Furthermore, since a portable X-ray fluorescence analyzer that can be carried is used, measurements can be performed easily and quickly even on site.
以上、本発明の実施形態について詳細に説明したが、本発明はこれに限定されず、本発明の要旨を逸脱しない範囲において、各種の改良や変形を行ってもよいのはいうまでもない。 As mentioned above, although embodiment of this invention was described in detail, it cannot be overemphasized that this invention is not limited to this, In the range which does not deviate from the summary of this invention, various improvement and deformation | transformation may be performed.
例えば、上述の実施形態では、Ｃｒ含有合金がニッケルクロム鋼又はクロムモリブデン鋼である例について説明したが、本発明におけるＣｒ含有合金は、ベース金属元素に対して少なくともクロム及びクロム以外の金属元素が添加された合金であれば、特に限定されない。
また、ベース金属元素に対してクロムを含む３種類以上の金属元素が添加されたＣｒ含有合金の場合、クロム及びクロム以外の添加量が最も多い金属元素の濃度と浸炭深さとの関係を予め求めて、浸炭深さの測定を行うことが好ましい。このように添加量が多い金属元素をパラメータとして用いることで、浸炭深さの測定精度が向上する。
For example, in the above-described embodiment, the example in which the Cr-containing alloy is nickel-chrome steel or chromium-molybdenum steel has been described, but the Cr-containing alloy in the present invention has at least a metal element other than chromium and chromium with respect to the base metal element. There is no particular limitation as long as it is an added alloy.
In addition, in the case of a Cr-containing alloy in which three or more kinds of metal elements including chromium are added to the base metal element, the relationship between the concentration of the metal element having the largest addition amount other than chromium and chromium and the carburization depth is obtained in advance. Thus, it is preferable to measure the carburization depth. By using a metal element with a large amount of addition as a parameter in this way, the measurement accuracy of carburization depth is improved.
１０ 近似曲線
２０ 近似曲線
10
Claims (4)
浸炭深さが異なるＣｒ含有合金の複数の試料についてポータブル型蛍光Ｘ線分析装置により分析を行って、クロム及びクロム以外の金属元素の濃度と浸炭深さとの関係を予め求めておき、
測定対象物であるＣｒ含有合金について前記ポータブル型蛍光Ｘ線分析装置により分析を行って、該測定対象物中のクロム及びクロム以外の金属元素の濃度を測定し、
予め求めた前記関係に基づいて、前記測定対象物中のクロム及びクロム以外の金属元素の濃度の測定結果から、前記測定対象物の浸炭深さを求めることを特徴とするＣｒ含有合金の浸炭深さ測定方法。 A method for measuring a carburization depth in a surface layer of a Cr-containing alloy in which at least chromium and a metal element other than chromium are added to a base metal element as a main component,
Analyzing a plurality of Cr-containing alloy samples having different carburizing depths with a portable X-ray fluorescence analyzer, and obtaining in advance the relationship between the concentration of chromium and metal elements other than chromium and the carburizing depth,
Analyzing the Cr-containing alloy that is the object to be measured by the portable fluorescent X-ray analyzer, and measuring the concentration of chromium and metal elements other than chromium in the object to be measured,
Based on the relationship obtained in advance, the carburization depth of the Cr-containing alloy is characterized in that the carburization depth of the measurement object is obtained from the measurement results of the concentrations of chromium and metal elements other than chromium in the measurement object. Measuring method.
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