JPH1183707A - Method and apparatus for developing intergranular fracture of metal material - Google Patents
Method and apparatus for developing intergranular fracture of metal materialInfo
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- JPH1183707A JPH1183707A JP9243723A JP24372397A JPH1183707A JP H1183707 A JPH1183707 A JP H1183707A JP 9243723 A JP9243723 A JP 9243723A JP 24372397 A JP24372397 A JP 24372397A JP H1183707 A JPH1183707 A JP H1183707A
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、オージェ電子分析
法による粒界偏析元素の分析を行う際の金属、鉄鋼材料
等の粒界破面の現出方法に係り、粒界破断面を効率的に
現出するための方法と装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for revealing grain boundary fracture surfaces of metals, steel materials and the like when analyzing grain boundary segregation elements by Auger electron analysis. And a method and apparatus for exposing the same.
【０００２】[0002]
【従来の技術】鉄鋼、金属材料の脆性は、結晶粒界に偏
析するＰ，Ｃ，Ｓ等の濃度に影響される。低合金鋼の高
温焼き戻し脆性はその一例である。粒界偏析元素を定量
分析する方法としては、たとえば、オージェ電子分析法
（以下、ＡＥＳ略記する）が挙げられる。ＡＥＳでは、
分析深さが材料表面から数ｎｍと極めて浅く、粒界に偏
析する厚さ数原子層のＰ，Ｓ等の偏析元素を高感度に分
析できる。この利点を生かすためにはＡＥＳの装置内の
超高真空中で材料を破断して、粒界破面を現出させるこ
とが必要である。その理由は、大気中で材料を破断して
も、粒界表面にＮ 2 、Ｏ2 、Ｈ2 Ｏ、ＣＯ2 等の大気中
のガス分子が厚く吸着して偏析元素を覆い隠してしま
い、分析できなくなるためである。2. Description of the Related Art The brittleness of steel and metallic materials is localized at grain boundaries.
It is affected by the concentration of P, C, S, etc. to be precipitated. Low alloy steel high
Hot temper brittleness is one example. Quantify grain boundary segregation elements
For example, Auger electron analysis
(Hereinafter abbreviated as AES). At AES,
The analysis depth is extremely shallow from the material surface, a few nanometers,
Segregated elements such as P and S in several atomic layers to be separated with high sensitivity
Can be analyzed. In order to take advantage of this advantage,
Breaking the material in an ultra-high vacuum to reveal grain boundary fracture surfaces
Is necessary. The reason is that the material breaks in the atmosphere
Also, N Two, OTwo, HTwoO, COTwoEtc. in the atmosphere
Gas molecules adsorb thickly and obscure the segregated elements.
This is because analysis cannot be performed.
【０００３】一般に、ＡＥＳ装置内での粒界破断法とし
ては、例えば、志水隆一・吉原一紘編「ユーザーのため
の実用オージェ電子分光法」（共立出版、第８章、ｐ．
１５３〜１５５）や Transaction of the ASM 62(3)(19
69) p.776 で知られる冷却破断方法がある。これは、Ａ
ＥＳ装置に取り付けられた材料を−１００℃近くまで冷
却し、鋼の低温脆性を利用して外部からの衝撃により材
料試験片を粒界で破断する機構を利用する方法である。[0003] In general, as a method of breaking a grain boundary in an AES apparatus, for example, "Actual Auger Electron Spectroscopy for Users" edited by Ryuichi Shimizu and Kazuhiro Yoshihara (Kyoritsu Shuppan, Chapter 8, p.
153-155) and Transaction of the ASM 62 (3) (19
69) There is a cooling rupture method known on p.776. This is A
This method uses a mechanism in which a material attached to an ES device is cooled to near -100 ° C, and a material test piece is broken at a grain boundary by an external impact using low-temperature brittleness of steel.
【０００４】靱性に富む金属、低合金鋼のように−１０
０℃程度の冷却では粒界で破断しない材料については、
特開昭５９−１３８９３６号のように、分析装置内に１
００〜７６００Ｔｏｒｒ（１０気圧）の高圧水素を導入
し、装置内で試料に低歪み速度の繰り返し応力を付与し
て粒界で破断させやすくする方法が知られている。この
方法は、材料に生じた歪みを通じて水素を粒界に吸収さ
せて、粒界を数多く露出させようとするものである。[0004] Tough metals, such as low alloy steels, have a
For materials that do not break at grain boundaries when cooled to about 0 ° C,
As disclosed in JP-A-59-138936, one
There is known a method in which high-pressure hydrogen of 100 to 7600 Torr (10 atm) is introduced to apply a repetitive stress at a low strain rate to a sample in an apparatus to easily break at a grain boundary. In this method, hydrogen is absorbed in a grain boundary through strain generated in a material, and a large number of grain boundaries are exposed.
【０００５】一方、装置外で粒界破断を促進させるため
の処理方法としては、特開昭６３−１１５０４１号のよ
うに、破断直前まで５００℃の高温での定荷重を付与
（クリープ付与）し、続いて低歪み速度引っ張り付与を
施して結晶粒界に損傷を与えて、粒界を選択的に露出さ
せる方法が知られている。On the other hand, as a processing method for accelerating grain boundary rupture outside the apparatus, a constant load at a high temperature of 500 ° C. is applied (creep is applied) until immediately before the rupture, as disclosed in JP-A-63-115041. Then, there is known a method in which a crystal grain boundary is damaged by applying a low strain rate tensile force to selectively expose the grain boundary.
【０００６】材料を液体窒素で−１００℃付近まで冷却
し、衝撃を加える破断方法では、靱性に優れ、耐低温脆
性の良好な鉄鋼、金属材料では延性もしくは粒内破面と
なる場合が多く、粒界を現出することは極めて困難であ
る。また、分析装置内に高圧水素を導入して破断する方
法では、高圧水素を導入するための特殊な容器、ガス導
入系や材料に応力を付与するための機構が必要となり、
装置の構造が複雑かつ大型化し、操作性及び経済性に問
題があった。[0006] In a fracture method in which a material is cooled to around -100 ° C with liquid nitrogen and subjected to impact, a steel or a metal material having excellent toughness and low temperature brittleness resistance often has a ductile or intragranular fracture surface. It is extremely difficult to reveal grain boundaries. In addition, the method of introducing high-pressure hydrogen into the analyzer and breaking it requires a special container for introducing high-pressure hydrogen, a mechanism for applying stress to the gas introduction system and the material,
The structure of the device is complicated and large, and there is a problem in operability and economy.
【０００７】また、クリープ付与に続き、低歪み速度で
の引張付与を施して粒界に損傷を与える方法では、クリ
ープ付与を５００℃の高温で行うため熱的拡散により、
粒界から粒内に元素が移動し、粒界元素濃度がクリープ
付与前後で変化し、正確な分析ができないという問題が
あった。さらに、本破断法では、低歪み速度ではあるも
のの、材料に引張応力を付与するため、材料が損傷を受
け、数多くのクラックが材料内に発生する。このクラッ
ク発生部には、大気中のＮ2 、Ｏ2 、Ｈ2 Ｏ、ＣＯ2 等
のガスが浸入するため、所定の形状に加工した材料試験
片を超高真空装置内に導入したとき、試験片からのガス
発生のため装置内の真空度が低下し、材料破断後に露出
した粒界に、装置内へ放出されたガス分子が吸着して分
析精度が低下するという問題があった。In the method of applying a tensile force at a low strain rate and damaging the grain boundaries following the creep application, since the creep is applied at a high temperature of 500 ° C., thermal diffusion is performed.
There is a problem that the element moves from the grain boundary to the inside of the grain, and the concentration of the grain boundary element changes before and after the creep is applied, so that accurate analysis cannot be performed. Further, in the fracture method, although a low strain rate is applied, a tensile stress is applied to the material, so that the material is damaged and many cracks are generated in the material. Since a gas such as N 2 , O 2 , H 2 O, and CO 2 in the atmosphere enters the crack generating portion, when a material test piece processed into a predetermined shape is introduced into an ultra-high vacuum device, Due to the generation of gas from the test piece, the degree of vacuum in the apparatus is reduced, and there is a problem that the gas molecules released into the apparatus are adsorbed on the grain boundaries exposed after the material is broken, thereby lowering the analysis accuracy.
【０００８】材料に電解法で水素をチャージする方法
は、比較的容易に水素を材料中に導入することが可能
で、金属材料は、導入された水素による脆化作用により
選択的に粒界を脆化させられるため、粒界面に沿って破
壊される。従って、ＡＥＳで粒界偏析元素を分析するた
めの粒界現出法としては、−１００℃付近の冷却で低温
脆性を示さない鋼、金属材料に対して、また高温で粒界
偏析元素が変化する材料に対して、有効な方法である。[0008] In the method of charging hydrogen to a material by electrolysis, hydrogen can be relatively easily introduced into the material, and the metal material selectively forms grain boundaries by embrittlement by the introduced hydrogen. Because it is embrittled, it is broken along grain boundaries. Therefore, as a grain boundary appearance method for analyzing grain boundary segregation elements by AES, the change of the grain boundary segregation elements in steels and metallic materials that do not show low-temperature brittleness at cooling around -100 ° C and at high temperatures This is an effective method for the material to be used.
【０００９】ステンレス鋼の鋭敏化処理材で、陰極に水
素チャージすることにより鋼の延性が低下することが、
日本金属学会誌、第４６巻、第９号、（１９８２）、
ｐ．８７７−８８６で知られており、この現象を利用し
て、オーステナイト系Ｆｅ−Ｎｉ−Ｃｒ合金の鋭敏化材
の粒界を露出させる方法としては、特開平０４−２８５
１８７号のように、電解法により合金中に水素をチャー
ジし、ついで材料を１００℃で加熱し、脱水素処理（デ
ィスチャージ）を行い、この水素チャージ・ディスチャ
ージを複数回くりかえした後、材料を破断して結晶粒界
を創出する方法が知られている。[0009] The stainless steel sensitizing material, it is possible to reduce the ductility of the steel by hydrogen charging the cathode,
Journal of the Japan Institute of Metals, Vol. 46, No. 9, (1982),
p. 877-886, and a method of utilizing this phenomenon to expose the grain boundaries of the sensitized material of an austenitic Fe-Ni-Cr alloy is disclosed in JP-A-04-285.
As in 187, hydrogen is charged into the alloy by the electrolytic method, then the material is heated at 100 ° C. to perform dehydrogenation (discharge), and after repeating the hydrogen charge / discharge several times, the material is broken. There is known a method of creating a crystal grain boundary.
【００１０】しかし、電解法で水素チャージをした後に
ディスチャージを行う方法では、水素を材料にチャージ
することによって、水素は金属表面から内部さらに結晶
粒界に拡散し、粒界を脆化させるが、その後の脱水素処
理を行うために、水素の材料内部への拡散が生じると同
時に、材料表面からの水素の放出も生じる。従って、脱
水素処理の温度、時間によっては、水素をチャージして
生じた粒界での脆化層が消失し、水素フリーの状態に回
復し、材料を破断した時に創出される粒界破面の面積率
が低下する。また、ディスチャージ処理をしない場合で
も、水素は拡散速度が大きいため、室温では容易に材料
から大気中に放出されるため、チャージした水素の大半
が材料中から放出され、水素による粒界での脆化層が消
失して、破断したときに創出される粒界破面の面積率が
低下するという問題があった。However, in the method of performing discharge after charging hydrogen by the electrolytic method, hydrogen diffuses from the metal surface to the inside and further to the crystal grain boundaries by charging the material with hydrogen, thereby making the grain boundaries embrittled. In order to perform the subsequent dehydrogenation treatment, hydrogen diffuses into the material, and at the same time, hydrogen is released from the material surface. Therefore, depending on the temperature and time of the dehydrogenation treatment, the brittle layer at the grain boundary generated by charging hydrogen disappears, recovers to a hydrogen-free state, and the grain boundary fracture surface created when the material is broken. Area ratio decreases. Further, even when the discharge treatment is not performed, hydrogen diffuses at a high rate and is easily released from the material into the atmosphere at room temperature. Therefore, most of the charged hydrogen is released from the material, and the hydrogen is brittle at the grain boundary. However, there is a problem in that the area layer of the grain boundary fracture surface created when the fractured layer is lost and the fracture occurs is reduced.
【００１１】電解法で水素を金属材料にチャージする装
置としては、特開平０４−２８５１８７号に知られるよ
うに、５０℃の１Ｎ−硫酸溶液（ＮａＡｓＯ3 を添加）
中で定電流法による陰極水素チャージ法が知られてい
る。この方法では、陰極での試験片表面全面に、白金電
極を対極（陽極）に配置し、さらに参照電極により電位
変化を記録する構成になっている。試験片表面を覆うよ
うに白金電極を対峙させると、試験片全体に水素が侵入
し、長時間のチャージ時間を必要とすること、また参照
電極の電位記録だけでは、電解液温度変化及び長時間の
水素チャージのために電解液が蒸発することによる液濃
度変化にともなうチャージ水素量が大きく変動するとい
う問題があった。さらに、このように水素チャージ量の
変動が生じるような装置で電解水素チャージを行った場
合に、材料中に導入される水素濃度が大きく変化し、水
素脆化による粒界破面の面積率が変化するという問題が
あった。As an apparatus for charging hydrogen to a metal material by an electrolysis method, as disclosed in Japanese Patent Application Laid-Open No. 04-285187, a 1N sulfuric acid solution at 50 ° C. (with NaAsO 3 added)
Among them, a cathode hydrogen charging method using a constant current method is known. In this method, a platinum electrode is arranged on a counter electrode (anode) over the entire surface of a test piece at a cathode, and a change in potential is recorded by a reference electrode. When the platinum electrode is opposed to cover the surface of the test piece, hydrogen penetrates into the whole test piece and requires a long charge time. There is a problem that the amount of charged hydrogen fluctuates greatly due to a change in solution concentration due to evaporation of the electrolytic solution due to hydrogen charging. Furthermore, when electrolytic hydrogen charging is performed by such a device that causes a change in the amount of hydrogen charge, the concentration of hydrogen introduced into the material changes greatly, and the area ratio of the grain boundary fracture surface due to hydrogen embrittlement is reduced. There was a problem of change.
【００１２】[0012]
【発明が解決しようとする課題】本発明は、前記問題点
を解決し、鉄鋼、金属材料の粒界偏析元素分析のため、
より多くの粒界破面を効率的に現出させる技術を提供し
ようとする。DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and is intended for analysis of grain boundary segregation elements in steel and metal materials.
An attempt is made to provide a technique for efficiently revealing more grain boundary fracture surfaces.
【００１３】[0013]
【課題を解決するための手段】すなわち、本発明は前記
問題点を解決するために、電解水素チャージ法で、金属
鉄鋼材料の切欠き部近傍に選択的に水素を導入し、該材
料中の水素濃度を３ｐｐｍ以上とし、ついで該材料表面
にＮｉ電解メッキして該材料を液体窒素中に保存した
後、その材料を破断することを特徴とする金属材料の粒
界破面の現出方法を提供する。さらに、本発明は、切欠
き部を有する金属鉄鋼片を陰電極として該切欠き部に水
素をチャージする電解水素チャージ装置であって、微量
の亜砒素酸ナトリウムを含む０．５〜３Ｎの硫酸溶液で
ある電解液を含む電解槽と、電解液の温度を一定に保つ
温度制御手段と、電解液量を一定に保つ自動定量送液手
段と、陰電極である金属鉄鋼材料の切欠き部近傍に対峙
して設置される陽電極と、該陰電極および陽電極に電解
電圧を印荷する電源とからなる電解水素チャージ装置を
提供する。That is, in order to solve the above-mentioned problems, the present invention selectively introduces hydrogen in the vicinity of a notch of a metallic steel material by an electrolytic hydrogen charging method, A method for producing a grain boundary fracture surface of a metal material, characterized in that the hydrogen concentration is 3 ppm or more, and then the material surface is Ni electroplated, the material is stored in liquid nitrogen, and then the material is broken. provide. Further, the present invention is an electrolytic hydrogen charging apparatus for charging hydrogen to the notch portion using a metal steel slab having the notch portion as a negative electrode, comprising 0.5-3N sulfuric acid containing a trace amount of sodium arsenite. An electrolytic cell containing an electrolytic solution as a solution, a temperature control means for keeping the temperature of the electrolytic solution constant, an automatic constant-quantity liquid sending means for keeping the amount of the electrolytic solution constant, and a vicinity of a notch of a metallic steel material as a negative electrode To provide an electrolytic hydrogen charging apparatus comprising: a positive electrode installed to face the negative electrode; and a power supply for applying an electrolytic voltage to the negative electrode and the positive electrode.
【００１４】[0014]
【発明の実施の形態】以下において本発明を詳細に説明
する。上記のとおり本発明法は、電解水素チャージ法
で、金属鉄鋼材料の切欠き部近傍に選択的に水素を導入
し、該材料中の水素濃度を３ｐｐｍ以上とし、ついで該
材料表面にＮｉ電解メッキして該材料を液体窒素中に保
存した後、その材料を破断する金属材料の粒界破面の現
出方法である。ここで、電解チャージ法とは、一定の温
度で電解溶液中で定電流法により、対照材料である陰極
に水素を浸入させる方法である。この方法では、陰極で
の試験片表面に、白金電極を対極（陽極）に配置する構
成になっている。本発明では材料全体でなく切欠き部近
傍に選択的に水素をチャージすることを特徴とする。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. As described above, the method of the present invention is an electrolytic hydrogen charging method in which hydrogen is selectively introduced in the vicinity of a notch in a metallic steel material, the hydrogen concentration in the material is adjusted to 3 ppm or more, and then Ni electrolytic plating is performed on the surface of the material. Then, the material is stored in liquid nitrogen, and then the material is broken. Here, the electrolytic charging method is a method in which hydrogen enters a cathode as a control material by a constant current method in an electrolytic solution at a constant temperature. In this method, a platinum electrode is arranged on a surface of a test piece at a cathode as a counter electrode (anode). The present invention is characterized in that hydrogen is selectively charged not only in the whole material but in the vicinity of the notch.
【００１５】本発明方法の対象となる金属鉄鋼材料は、
鉄鋼材であれば特に限定されないが、オーステナイト系
ステンレス鋼、低合金鋼、炭素鋼等にも適用することが
できる。試験片とする金属鉄鋼材料には、破断箇所とな
る約０．５ｍｍ深さの切欠きを入れる。[0015] The metallic steel material to be subjected to the method of the present invention includes:
The material is not particularly limited as long as it is a steel material, but can be applied to austenitic stainless steel, low alloy steel, carbon steel, and the like. A notch having a depth of about 0.5 mm, which is a break point, is made in the metallic steel material used as the test piece.
【００１６】材料中の切欠き部の水素濃度は３ｐｐｍ以
上にし、好ましくは４〜５ｐｐｍ、特に好ましくは４ｐ
ｐｍにする。材料中の水素濃度を３ｐｐｍ以上となるよ
うに電解法で水素をチャージすると、粒界破面の面積率
が著しく増加し、観察範囲が増加して、分析精度が向上
するからである。The hydrogen concentration in the notch in the material is 3 ppm or more, preferably 4 to 5 ppm, particularly preferably 4 ppm.
pm. If hydrogen is charged by electrolysis so that the hydrogen concentration in the material becomes 3 ppm or more, the area ratio of the grain boundary fracture surface is significantly increased, the observation range is increased, and the analysis accuracy is improved.
【００１７】Ｎｉ電解メッキは、好ましくはＮｉＳＯ4
１５０ｇ／ｌと塩化アンモニア１５ｇ／ｌのメッキ液組
成、２０〜２５℃、好ましくは２０℃のメッキ浴温度、
０．２〜２．０Ａ／ｄｍ2 、好ましくは０．５〜１Ａ／
ｄｍ2 の電流密度、２〜１０ｍｉｎ、好ましくは４〜６
ｍｉｎのメッキ時間の電解条件で行なう。ｐＨの調節は
希硫酸、および炭酸Ｎｉを添加して行なう。Ｎｉ電解メ
ッキにより、厚さ０．５μｍ以上、好ましくは１μｍ以
上のＮｉメッキを金属鉄鋼材料表面に付着させる。水素
導入の直後に材料試験片表面に水素の溶解度が高いＮｉ
メッキを行なうことにより、材料中の水素を外部へ透過
しにくくなり、材料からの水素の放出を少なくできる。The Ni electrolytic plating is preferably performed using NiSO 4
A plating bath composition of 150 g / l and ammonia chloride of 15 g / l, a plating bath temperature of 20 to 25 ° C., preferably 20 ° C.,
0.2 to 2.0 A / dm 2 , preferably 0.5 to 1 A / dm 2
dm 2 current density, 2-10 min, preferably 4-6
The plating is performed under the electrolysis conditions for a plating time of min. The pH is adjusted by adding dilute sulfuric acid and Ni carbonate. Ni plating having a thickness of 0.5 μm or more, preferably 1 μm or more is adhered to the surface of the metallic steel material by Ni electrolytic plating. Ni with high hydrogen solubility on the surface of the material specimen immediately after hydrogen introduction
By plating, it becomes difficult for hydrogen in the material to permeate to the outside, and the release of hydrogen from the material can be reduced.
【００１８】液体窒素中の保存は５分以上、好ましくは
３０分程度で、液体窒素中で保存する。これにより、金
属鉄鋼材料中での水素の拡散を抑制して、材料からの放
出を少なくできる。The storage in liquid nitrogen is performed for at least 5 minutes, preferably about 30 minutes, in liquid nitrogen. Thereby, the diffusion of hydrogen in the metallic steel material can be suppressed, and the release from the material can be reduced.
【００１９】破断は粒界表面にＮ2 、Ｏ2 、Ｈ2 Ｏ、Ｃ
Ｏ2 等の大気中のガス分子が厚く吸着して偏析元素を覆
い隠すことを防ぐために、ＡＥＳの装置内の超高真空中
で行なう。ＡＥＳ装置内での粒界破断法としては、例え
ば、志水隆一・吉原一紘編「ユーザーのための実用オー
ジェ電子分光法」（共立出版、第８章、ｐ．１５３〜１
５５）や Transaction of the ASM 62(3)(1969) p.776
で知られる冷却破断方法などの一般的な方法を用いるこ
とができる。The fracture is caused by N 2 , O 2 , H 2 O, C
In order to prevent the gas molecules in the atmosphere such as O 2 from adsorbing thickly to cover the segregated elements, it is performed in an ultra-high vacuum in the AES apparatus. Examples of the grain boundary breaking method in the AES apparatus include, for example, “Practical Auger Electron Spectroscopy for Users” edited by Ryuichi Shimizu and Kazuhiro Yoshihara (Kyoritsu Shuppan, Chapter 8, pp. 153-1)
55) and Transaction of the ASM 62 (3) (1969) p.776
A general method such as a cooling rupture method known in US Pat.
【００２０】本発明方法に用いる電解チャージ法は本発
明装置を用いれば好適に実施でき、本装置を用いること
により金属鉄鋼材料中の水素濃度を３ｐｐｍ以上に容易
に制御することができる。以下に本発明の装置の好適例
を説明した図２を用いて本発明装置を説明する。本発明
装置は図示例に限定されるものではない。図２に示す本
発明装置は切欠き１を有する金属鉄鋼片２を陰電極と
し、電解液６を充たした電解槽７中で白金電極８を陽極
として電解を行なって水素を切欠き１中に浸入させる。
別の切欠き４を有する金属鉄鋼片３を同様に陰電極と
し、別の白金電極９をこの陰極に対峙する構成とすれば
複数の鉄鋼片を同時に水素をチャージさせることができ
る。The electrolytic charging method used in the method of the present invention can be suitably carried out by using the apparatus of the present invention, and the hydrogen concentration in the metallic steel material can be easily controlled to 3 ppm or more by using the apparatus. Hereinafter, the apparatus of the present invention will be described with reference to FIG. 2, which illustrates a preferred example of the apparatus of the present invention. The device of the present invention is not limited to the illustrated example. In the apparatus of the present invention shown in FIG. 2, a metal steel piece 2 having a notch 1 is used as a negative electrode, and electrolysis is performed using a platinum electrode 8 as an anode in an electrolytic cell 7 filled with an electrolytic solution 6 to remove hydrogen into the notch 1. Let infiltrate.
If the metal steel piece 3 having another notch 4 is similarly used as a negative electrode and another platinum electrode 9 is configured to face the cathode, hydrogen can be simultaneously charged in a plurality of steel pieces.
【００２１】電解液６は、微量の亜砒素酸ナトリウムを
含む０．５〜3 Ｎの硫酸溶液を用いる。電解液に含まれ
る亜砒素酸の量は微量であるが、好ましくは０．５ｇ／
ｌ〜１ｇ／ｌである。微量の亜砒素酸ナトリウムの添加
により、陰極での急激な反応進行による水素ガスの発
生、付着を抑制し、陰極反応を継続させることができ
る。電解液の硫酸濃度は０．５〜３Ｎであり、好ましく
は１〜２Ｎである。この硫酸濃度により材料の水素濃度
を３ｐｐｍ以上とするための電解条件（電流、温度、時
間）を設定することが可能となるからである。As the electrolytic solution 6, a 0.5 to 3N sulfuric acid solution containing a trace amount of sodium arsenite is used. The amount of arsenous acid contained in the electrolyte is very small, but is preferably 0.5 g /
1 to 1 g / l. By adding a trace amount of sodium arsenite, generation and attachment of hydrogen gas due to rapid reaction progress at the cathode can be suppressed, and the cathode reaction can be continued. The sulfuric acid concentration of the electrolyte is 0.5 to 3N, preferably 1 to 2N. This is because the concentration of sulfuric acid makes it possible to set electrolysis conditions (current, temperature, time) for setting the hydrogen concentration of the material to 3 ppm or more.
【００２２】本発明装置は温度制御手段を備えている。
温度制御手段は、電解液の温度を一定に保つコントロー
ラー１０、温度センサ１１とヒータ１２で構成される。
温度センサ１１は好ましくは電解液６中に設けられる熱
電対等の温度計で、ヒータ１２は電解槽７の好ましくは
底部１７に設けられる電熱線等の加熱装置である。温度
センサ１１とヒータ１２はそれぞれコントローラー１０
に電気的に接続されている。温度センサ１１により電解
液６の温度を検知して、電解液６の温度が所望の温度を
下回っていた場合はコントローラー１０からの指令によ
りヒータ１２が作動し電解液６が加熱される。この様に
して常に電解液６の温度を一定に保つことができる。温
度を一定に保つのは電解でチャージされる水素量は、電
解液の温度により変動するからである。電解液の温度を
一定に保持することにより、再現性よく材料中の水素濃
度を３ｐｐｍ以上に制御できる。The device of the present invention has temperature control means.
The temperature control means includes a controller 10 for keeping the temperature of the electrolyte constant, a temperature sensor 11 and a heater 12.
The temperature sensor 11 is preferably a thermometer such as a thermocouple provided in the electrolyte 6, and the heater 12 is a heating device such as a heating wire provided on the bottom 17 of the electrolytic cell 7. The temperature sensor 11 and the heater 12 are connected to the controller 10 respectively.
Is electrically connected to The temperature of the electrolytic solution 6 is detected by the temperature sensor 11, and if the temperature of the electrolytic solution 6 is lower than the desired temperature, the heater 12 is operated by a command from the controller 10 to heat the electrolytic solution 6. In this way, the temperature of the electrolytic solution 6 can always be kept constant. The temperature is kept constant because the amount of hydrogen charged by electrolysis varies depending on the temperature of the electrolytic solution. By keeping the temperature of the electrolytic solution constant, the hydrogen concentration in the material can be controlled to 3 ppm or more with good reproducibility.
【００２３】自動定量送液手段は液面センサ１３、ポン
プ１４、および蒸留水タンク１５を有する。液面センサ
１３により電解液６の液量を検知し、水分の蒸発により
電解液６が所望の液量すなわち所望の濃度に達していな
い場合は、ポンプ１４が蒸留水タンク１５より電解槽７
へ蒸留水を供給する。これにより電解液６の濃度、ｐＨ
を一定に保つためである。電解でチャージされる水素量
は、電解液濃度、ｐＨ値により変動する。本発明は長時
間の水素チャージ中に蒸発する電解液６の減少を検知し
て蒸留水を自動的に補給する自動定量送液手段を備える
ことにより、電解液濃度、ｐＨを一定に保持することが
できるので、再現性よく材料中の水素濃度を３ｐｐｍ以
上に制御できる。The automatic liquid sending means has a liquid level sensor 13, a pump 14, and a distilled water tank 15. The liquid level of the electrolytic solution 6 is detected by the liquid level sensor 13, and when the electrolytic solution 6 does not reach a desired liquid amount, that is, a desired concentration due to evaporation of water, the pump 14 is moved from the distilled water tank 15 to the electrolytic tank 7.
And supply distilled water. Thereby, the concentration and pH of the electrolytic solution 6
In order to keep constant. The amount of hydrogen charged by electrolysis varies depending on the concentration of the electrolyte and the pH value. The present invention is to maintain a constant electrolyte concentration and pH by providing an automatic quantitative liquid sending means for automatically replenishing distilled water by detecting a decrease in the amount of the electrolyte 6 evaporating during a long hydrogen charge. Therefore, the hydrogen concentration in the material can be controlled to 3 ppm or more with good reproducibility.
【００２４】電極は陰電極が金属鉄鋼材料２で、これに
は破断箇所となる切欠き１を設ける。陽電極は白金電極
８で、陽電極は該材料の切欠き１に対峙するように配置
されている。白金電極８の形状は、切欠き１が金属鉄鋼
材料中に設けられたほぼ水平な線状である場合はその線
状から離隔して設けられる円環でその幅は切欠き１の幅
よりやや広くするのが好ましい。すなわち陽極８は切欠
き１から離隔した位置で切欠き１の形状を囲むように対
向させるのが好ましい。このような配置により、水素の
導入が切欠き１近傍に限定されるようになり、後に破断
して粒界破面を現出させる破断部に直接水素を導入で
き、破断部近傍だけの粒界脆化を促進することが可能と
なる。また特定の箇所のみに水素をチャージするのでチ
ャージ時間を短縮することができる。また、電極には電
源であるポテンショスタット１６が連結されており、陰
電極、陽電極はそれぞれポテンショスタットのマイナス
端子、プラス端子に接続されている。ポテンショスタッ
ト１６により自動的に電極に流れる電流電位を一定に保
つ。電解でチャージされる水素量は、電解電流により変
動するため、ポテンショスタットを設置することにより
再現性よく材料中の水素濃度を３ｐｐｍ以上に制御でき
るようになる。The electrode is made of a metallic steel material 2 having a notch 1 at a breaking point. The positive electrode is a platinum electrode 8 which is arranged so as to face the notch 1 of the material. When the notch 1 is a substantially horizontal line provided in a metallic steel material, the shape of the platinum electrode 8 is a ring provided apart from the line, and the width thereof is slightly larger than the width of the notch 1. Preferably, it is wider. That is, it is preferable that the anode 8 is opposed to the notch 1 so as to surround the shape of the notch 1 at a position separated from the notch 1. With such an arrangement, the introduction of hydrogen is limited to the vicinity of the notch 1, and the hydrogen can be directly introduced into the fracture portion that is later broken to reveal the grain boundary fracture surface, and the grain boundary only in the vicinity of the fracture portion can be introduced. Embrittlement can be promoted. Further, since hydrogen is charged only at a specific location, the charging time can be reduced. A potentiostat 16 as a power supply is connected to the electrode, and the negative electrode and the positive electrode are connected to the negative terminal and the positive terminal of the potentiostat, respectively. The potential of the current automatically flowing through the electrode is kept constant by the potentiostat 16. Since the amount of hydrogen charged in the electrolysis varies depending on the electrolysis current, it is possible to control the hydrogen concentration in the material to 3 ppm or more with good reproducibility by installing a potentiostat.
【００２５】[0025]
【作用】金属、鉄鋼材料に水素を添加すると、材料は脆
化する（水素脆化）。材料中の水素は主に結晶粒界に沿
って分布し、粒界が脆化するからである。本発明は、前
記現象をＡＥＳの粒界偏析元素分析のための粒界破面の
現出法に応用したもので、本発明によると、例えば、材
料を３．５ｍｍφ×１７．５ｍｍの丸棒に加工して、そ
の長軸方向のほぼ中央部に、円周に沿って、試験片の破
断箇所となる約０．５ｍｍ深さの切欠きを入れ、そのＡ
ＥＳの破断用試験片の切欠き１に対峙するように切欠き
とほぼ同じ幅か少し大である幅の陽電極を配置して、電
解で水素チャージをする。これにより、水素の導入は、
切欠き近傍に限定されるようになり、後に破断して粒界
破面を出現させる破断部に直接水素を導入できるように
なり、破断部近傍だけの粒界脆化を促進することが可能
となる。When hydrogen is added to a metal or steel material, the material becomes brittle (hydrogen embrittlement). This is because hydrogen in the material is mainly distributed along crystal grain boundaries, and the grain boundaries are embrittled. The present invention is an application of the above phenomenon to a method for revealing a grain boundary fracture surface for AES grain boundary segregation element analysis. According to the present invention, for example, a 3.5 mmφ × 17.5 mm round bar is used for a material. A notch with a depth of about 0.5 mm, which is a break point of the test piece, was formed along the circumference at a substantially central portion in the longitudinal direction thereof,
A positive electrode having a width substantially the same as or slightly larger than the notch is arranged so as to face the notch 1 of the ES fracture test piece, and hydrogen charging is performed by electrolysis. This allows the introduction of hydrogen to
Being limited to the vicinity of the notch, hydrogen can be directly introduced into the fracture part where the fracture occurs later and the grain boundary fracture surface appears, and it is possible to promote grain boundary embrittlement only in the vicinity of the fracture part. Become.
【００２６】また、本発明によると、水素導入の直後に
材料試験片表面にＮｉメッキをし、さらに液体窒素中で
保存することにより、材料中の水素を外部へ透過しにく
くするとともに、材料中での水素の拡散を抑制して、材
料からの水素の放出を少なくできる。Further, according to the present invention, the surface of the material test piece is plated with Ni immediately after the introduction of hydrogen, and is further stored in liquid nitrogen, so that hydrogen in the material is hardly permeated to the outside. Of hydrogen from the material can be reduced by suppressing the diffusion of hydrogen in the material.
【００２７】図１は、電解法でチャージした炭素鋼中で
の水素濃度（ｐｐｍ）とＡＥＳ分析装置内で炭素鋼の試
験片を破断した後の粒界をＳＥＭ（走査電子顕微鏡）に
より観察した際の、全体面積に対する粒界破面の面積率
（％）の関係を示す。炭素鋼中の水素量は、試験片
（３．５ｍｍφ×１７．５ｍｍの丸棒）を１０００℃の
炉中に２〜３秒導入し、発生するＨ2 ガスを、内蔵され
た熱伝導度検出器により分析する水素分析装置を用いて
測定した。図１によると、水素をチャージしない炭素鋼
の水素濃度は０．３〜０．５ｐｐｍで、粒界破面率は０
％即ちほぼ全面延性破面（あるいは全面粒内破面）であ
るが、水素をチャージして鋼中での水素濃度が３ｐｐｍ
になると粒界破面率は約５０％となり著しく増加し、さ
らに、鋼中水素濃度が４ｐｐｍ以上になると、粒界破面
率は飽和する傾向にあることが分かる。本発明では、材
料中の水素濃度が３ｐｐｍ以上となるように電解法で水
素をチャージすることにより、粒界破面の面積率が著し
く増加し、観察範囲が増加して、分析精度が向上する。FIG. 1 shows the SEM (scanning electron microscope) of the hydrogen concentration (ppm) in the carbon steel charged by the electrolytic method and the grain boundary after breaking the carbon steel test piece in the AES analyzer. In this case, the relation of the area ratio (%) of the grain boundary fracture surface to the entire area is shown. The amount of hydrogen in carbon steel can be determined by introducing a test specimen (3.5 mmφ × 17.5 mm round bar) into a furnace at 1000 ° C. for 2 to 3 seconds, and detecting the generated H 2 gas with built-in thermal conductivity. It measured using the hydrogen analyzer which analyzes with a spectrometer. According to FIG. 1, the hydrogen concentration of carbon steel not charged with hydrogen is 0.3 to 0.5 ppm, and the grain boundary fracture rate is 0%.
%, That is, almost the entire surface is a ductile fracture surface (or the whole surface is an intragranular fracture surface).
It can be seen that the grain boundary fracture rate tends to be saturated when the hydrogen concentration in the steel becomes 4 ppm or more, and the grain boundary fracture rate tends to be saturated when the hydrogen concentration in the steel becomes 4 ppm or more. In the present invention, by charging hydrogen by electrolysis so that the hydrogen concentration in the material is 3 ppm or more, the area ratio of the grain boundary fracture surface is significantly increased, the observation range is increased, and the analysis accuracy is improved. .
【００２８】材料中への水素濃度を３ｐｐｍ以上とする
ためには、電解水素チャージの条件を設定する必要があ
る。本発明によれば、微量の亜砒素酸ナトリウムを含む
０．５〜３Ｎの硫酸溶液を電解液とすることで、材料の
水素濃度を３ｐｐｍとする電解条件（電流、温度、時
間）を設定することが可能となる。ここで、微量の亜砒
素酸ナトリウムは、陰極での急激な反応進行による水素
ガスの発生、付着を抑制し、陰極反応を継続させる。電
解法によりチャージされる水素量は、電解液の温度、電
解電流、電解液濃度、ｐＨ値により変動する。本発明の
装置を用いれば、電解電流を一定とするためのポテンシ
ョスタット、および温度を一定とするための温度制御手
段を取り付け、さらに長時間の水素チャージ中に蒸発す
る電解液の減少を検知して蒸留水を自動的に補給する自
動定量送液ポンプを有するので、電解液の温度および電
解液濃度、ｐＨを一定に保持することができ、材料中の
水素濃度を３ｐｐｍ以上に容易に制御できる。In order to set the hydrogen concentration in the material to 3 ppm or more, it is necessary to set conditions for electrolytic hydrogen charging. According to the present invention, a 0.5 to 3N sulfuric acid solution containing a trace amount of sodium arsenite is used as an electrolytic solution to set electrolysis conditions (current, temperature, and time) to make the hydrogen concentration of the material 3 ppm. It becomes possible. Here, the trace amount of sodium arsenite suppresses generation and adhesion of hydrogen gas due to rapid reaction progress at the cathode, and continues the cathode reaction. The amount of hydrogen charged by the electrolytic method varies depending on the temperature of the electrolytic solution, the electrolytic current, the concentration of the electrolytic solution, and the pH value. Using the apparatus of the present invention, a potentiostat for keeping the electrolytic current constant and a temperature control means for keeping the temperature constant are attached, and the decrease in the amount of the electrolytic solution that evaporates during prolonged hydrogen charging is detected. Has an automatic metering solution pump for automatically replenishing distilled water, so that the temperature of the electrolyte, the concentration of the electrolyte and the pH can be kept constant, and the hydrogen concentration in the material can be easily controlled to 3 ppm or more. .
【００２９】[0029]
【実施例】図２は、ポテンショスタット１６を用いた定
電流制御による陰極電解水素チャージ装置の構成図であ
る。例示した装置は、微量の亜砒素酸ナトリウムを含む
０．５〜１Ｎ硫酸溶液である電解液６を含む電解槽７の
なかに、陰極に所定の形状に加工された２個の材料試験
片２、３（炭素鋼）、陽極には各々の材料試験片のほぼ
中央部の切欠き１に対峙させた白金電極８、９が配置さ
れており、各々、ポテンショスタット１６のマイナス端
子、プラス端子に接続されている。この電解槽７には、
電解液の温度を温度センサ１１で検知して、温度コント
ローラー１０を通じて液温度を一定とするためのヒータ
１２が取り付けられている。そのため、電解液温度が上
昇すると、ヒータ１２に流れる電流を小さくして、液温
度を下げるように、逆に、液温度が下降した場合には、
ヒータ１２を流れる電流を大きくして、液温度を下げる
ようにコントローラー１０が作用する。さらに、水分の
蒸発による電解液の減少を検知するための液面センサ１
３と、蒸発した水分を蒸留水タンク１５から自動的に補
充するための送液ポンプ１４により構成されている。液
面センサ１３は、電解液６の減少を検知すると、送液ポ
ンプ１４が作動して、蒸留水を電解液６に補充するよう
作用する。FIG. 2 is a block diagram of a cathodic electrolysis hydrogen charging apparatus by constant current control using a potentiostat 16. The illustrated apparatus is composed of two material test pieces 2 processed into a predetermined shape in a cathode in an electrolytic cell 7 containing an electrolytic solution 6 which is a 0.5 to 1 N sulfuric acid solution containing a trace amount of sodium arsenite. , 3 (carbon steel) and the anode are provided with platinum electrodes 8 and 9 facing the notch 1 at substantially the center of each material test piece, and are connected to the minus terminal and the plus terminal of the potentiostat 16 respectively. It is connected. In this electrolytic cell 7,
A heater 12 for detecting the temperature of the electrolytic solution with a temperature sensor 11 and keeping the temperature of the electrolytic solution constant through a temperature controller 10 is provided. Therefore, when the temperature of the electrolyte rises, the current flowing through the heater 12 is reduced to lower the temperature of the electrolyte.
The controller 10 acts to increase the current flowing through the heater 12 and lower the liquid temperature. Further, a liquid level sensor 1 for detecting a decrease in electrolyte due to evaporation of water.
3 and a liquid feed pump 14 for automatically replenishing the evaporated water from a distilled water tank 15. When the liquid level sensor 13 detects a decrease in the electrolyte 6, the liquid supply pump 14 operates to act to replenish the distilled water to the electrolyte 6.
【００３０】第１表は、ポテンショスタットの電流値が
２５ｍＡ、電解液濃度１Ｎ、ヒータでの液温度設定５０
℃で８６．４ｋｓの水素チャージをおこなった時の鋼中
水素濃度の変動範囲を示している。第１表に示されるよ
うに、温度センサと液面センサを共に使用した本発明の
装置では、鋼中に導入される水素濃度の変動範囲が小さ
く、この変動範囲では、粒界破面面積率５０％以上とす
るために必要な３ｐｐｍ以上の鋼中水素濃度を達成する
ことができるという結果が得られた。図１は、陽極に、
材料試験片のほぼ中央部の切欠き部に対峙させるように
白金電極を配置せず、試験片全体に水素をチャージした
ときの粒界破面率と鋼中水素濃度の関係を、破断を行う
切欠き部に対峙させるように白金電極を配置する本発明
法と比較して示す。切欠き部に水素をチャージする本発
明法では、破断を行って観察分析する部分近傍にのみ水
素を導入して脆化させるために、著しく高い粒界破面率
で、粒界を現出させることが可能であるという結果が得
られた。Table 1 shows that the current value of the potentiostat is 25 mA, the concentration of the electrolyte is 1 N, and the temperature of the solution is set by a heater.
8 shows a fluctuation range of hydrogen concentration in steel when hydrogen charging at 86.4 ksec is performed at ° C. As shown in Table 1, in the apparatus of the present invention using both the temperature sensor and the liquid level sensor, the fluctuation range of the concentration of hydrogen introduced into the steel was small. The result that the hydrogen concentration in steel of 3 ppm or more necessary for achieving 50% or more can be achieved was obtained. Figure 1 shows the anode
The relationship between the grain boundary fracture rate and the hydrogen concentration in steel when the whole test piece is charged with hydrogen is broken without placing the platinum electrode so as to face the notch in the center of the material test piece. This is shown in comparison with the method of the present invention in which a platinum electrode is arranged so as to face the notch. According to the method of the present invention in which hydrogen is charged into the notch, hydrogen is introduced only in the vicinity of a portion to be analyzed by fracture and is embrittled, so that a grain boundary appears at an extremely high grain boundary fracture ratio. The result is that it is possible.
【００３１】 [0031]
【００３２】図３は、鋼中水素濃度と電解液温度、電解
液濃度、電解時間の関係を示す図である。これにより、
本発明の装置を用いる水素チャージの電解条件を決定で
きた。なお、水素チャージの電解電流は、１０〜１００
ｍＡの範囲で実験を行った結果、２５ｍＡの時に鋼中水
素濃度が最も高くなったので、２５ｍＡとした。図３か
ら、鋼中水素濃度は、電解液濃度１Ｎ、液温５０℃で最
も高くなることが明らかになり、電解液濃度および液温
のどちらがこの条件からはずれても鋼中水素濃度は低下
する。さらに電解時間の増加とともに鋼中水素濃度は増
加するが、１８０ｋｓ以上ではほぼ一定となることが判
明した。従って、電解液濃度を０．５〜３Ｎとした場合
には、液温を５０〜７０℃、電解時間を８６．４ｋｓ以
上とすることで、粒界破面率５０％以上とするために必
要な鋼中水素濃度３ｐｐｍ以上が達成できることがわか
った。FIG. 3 is a diagram showing the relationship between the hydrogen concentration in steel, the electrolyte temperature, the electrolyte concentration, and the electrolysis time. This allows
The electrolysis conditions for hydrogen charging using the apparatus of the present invention could be determined. The hydrogen charging electrolysis current is 10 to 100.
As a result of conducting an experiment in the range of mA, the hydrogen concentration in steel was highest at 25 mA. From FIG. 3, it is clear that the hydrogen concentration in steel is highest at an electrolyte concentration of 1 N and a liquid temperature of 50 ° C., and the hydrogen concentration in the steel decreases regardless of whether the electrolyte concentration or the liquid temperature deviates from these conditions. . Further, it was found that the hydrogen concentration in the steel increased with an increase in the electrolysis time, but became substantially constant at 180 ksec or more. Therefore, when the concentration of the electrolyte is 0.5 to 3 N, it is necessary to adjust the solution temperature to 50 to 70 ° C. and the electrolysis time to 86.4 ks or more to make the grain boundary fracture rate 50% or more. It was found that a high hydrogen concentration in steel of 3 ppm or more can be achieved.
【００３３】鋼中に導入された水素の外部への放出を抑
制するため、電解水素チャージ後の材料試験片を、Ｎｉ
電解メッキが施されたのち液体窒素（−１７０℃）中で
保存した。Ｎｉ電解メッキは、ＮｉＳＯ4 ：１５０ｇ／
ｌ、塩化アンモニア：１５ｇ／ｌ、ホウ酸：１５ｇ／
ｌ、電解液の水素イオン濃度ｐＨ５．８〜６．２、のメ
ッキ液組成で、メッキ浴温度：２０℃、電流密度：０．
５〜１Ａ／ｄｍ2 、メッキ時間：４〜６ｍｉｎの電解条
件で行った。電解液のｐＨ値はｐＨが高いときは希硫酸
を添加し、ｐＨが低いときは、炭酸Ｎｉを添加して調整
した。このメッキ条件で、厚さ約１μｍ（付着量約９ｇ
／ｍ2 ）以上のＮｉメッキが材料試験片表面に付着し
た。In order to suppress the release of hydrogen introduced into the steel to the outside, the material test piece after electrolytic hydrogen charging was replaced with Ni
After being subjected to electrolytic plating, it was stored in liquid nitrogen (-170 ° C). For Ni electrolytic plating, NiSO 4 : 150 g /
1, ammonia chloride: 15 g / l, boric acid: 15 g /
1, a plating solution composition having a hydrogen ion concentration of the electrolyte of pH 5.8 to 6.2, a plating bath temperature: 20 ° C., and a current density: 0.1.
The electrolysis was performed under the conditions of 5 to 1 A / dm 2 and a plating time of 4 to 6 min. The pH value of the electrolyte was adjusted by adding dilute sulfuric acid when the pH was high, and by adding Ni carbonate when the pH was low. Under these plating conditions, a thickness of about 1 μm (adhesion amount of about 9 g
/ M 2 ) or more Ni plating adhered to the surface of the material test piece.
【００３４】図４は、上記Ｎｉメッキを電解水素チャー
ジ後に実施したときの鋼中水素濃度と水素チャージ時間
との関係を、Ｎｉメッキを実施しない場合と比較した図
である。鋼中水素濃度は、電解水素チャージ時間の増加
と共に増加するが、１８０ｋｓで飽和する傾向にある。
Ｎｉをメッキをせずに液体窒素中で保温した試験片で
は、同一時間水素チャージしＮｉメッキを施した後、液
体窒素中で保温した試験片に比べて、鋼中水素濃度はか
なり少なく、１８０ｋｓのチャージ時間でも、鋼中水素
濃度は３ｐｐｍに達していなかった。従って、本発明で
は、水素チャージをした試験片の表面に電解でＮｉメッ
キを約１μｍ付着させるようにしたので、材料に導入し
た３ｐｐｍ以上の水素の外部への放出を抑制することが
可能になり、５０％以上の高い粒界破面率で、結晶粒界
を現出できるという結果が得られるようになった。な
お、上記の実施例では、対象とする材料としては、炭素
鋼の場合について説明したが、本発明はこれに限定する
ものではなく、薄鋼板、電磁鋼板、厚鋼板、綿棒鋼等の
鉄鋼材料や、結晶粒界を有する合金、金属材料でもよ
い。FIG. 4 is a diagram comparing the relationship between the hydrogen concentration in steel and the hydrogen charging time when the above-mentioned Ni plating is performed after electrolytic hydrogen charging, compared with the case where no Ni plating is performed. The hydrogen concentration in steel increases with an increase in the electrolytic hydrogen charging time, but tends to saturate at 180 ks.
In the test piece in which Ni was kept in liquid nitrogen without plating, the hydrogen concentration in the steel was considerably lower than that of the test piece kept in liquid nitrogen after hydrogen charging for the same time and applying Ni plating, and then 180 ks. , The hydrogen concentration in the steel did not reach 3 ppm. Therefore, in the present invention, approximately 1 μm of Ni plating is applied to the surface of the hydrogen-charged test piece by electrolysis, so that the release of 3 ppm or more of hydrogen introduced into the material to the outside can be suppressed. , 50% or more of the grain boundary fracture surface ratio, the result that a crystal grain boundary can be obtained can be obtained. In the above embodiment, the case where the target material is carbon steel has been described.However, the present invention is not limited to this, and steel materials such as a thin steel plate, an electromagnetic steel plate, a thick steel plate, and a cotton swab steel are used. Alternatively, an alloy or a metal material having a crystal grain boundary may be used.
【００３５】[0035]
【発明の効果】本発明によれば、試料材料の切欠き部に
選択的に水素をチャージすることにより、オージェ電子
分析法による粒界偏析元素の分析を行う際の分析試料と
して必要不可欠な粒界破断面を、より多く、効率よくか
つ再現性よく露出できることが可能となる。その結果、
靱性に優れ、−１００℃での低温脆性を示さない材料や
粒界での破壊を起こしにくい材料に対して、５０％以上
の高い粒界破面面積率の試験片を得ることが容易にでき
るようになり、オージェ分析時の分析対象となる結晶粒
界数が増加し、粒界偏析元素の定量分析精度を向上させ
うる。According to the present invention, by selectively charging hydrogen to the notch portion of a sample material, particles indispensable as an analysis sample when analyzing grain boundary segregation elements by Auger electron analysis. It is possible to expose more of the cross-sections efficiently and with good reproducibility. as a result,
For a material having excellent toughness and not exhibiting low-temperature brittleness at −100 ° C. or a material that does not easily break at a grain boundary, a test piece having a high grain boundary fracture surface area ratio of 50% or more can be easily obtained. As a result, the number of crystal grain boundaries to be analyzed during Auger analysis increases, and the accuracy of quantitative analysis of grain boundary segregated elements can be improved.
【図１】 鋼中水素濃度と粒界破面率の関係図である。FIG. 1 is a graph showing the relationship between the hydrogen concentration in steel and the grain boundary fracture ratio.
【図２】 電解水素チャージ装置の構成を示す側面図で
ある。FIG. 2 is a side view showing a configuration of an electrolytic hydrogen charging device.
【図３】 電解水素チャージ装置で水素チャージを実施
するための、電解条件を示す図で、鋼中水素濃度と電解
液濃度、液温度、電解時間の関係図である。FIG. 3 is a diagram showing electrolysis conditions for carrying out hydrogen charging with an electrolytic hydrogen charging device, and is a diagram showing the relationship between the hydrogen concentration in steel, the electrolyte solution concentration, the solution temperature, and the electrolysis time.
【図４】 水素チャージ後のＮｉメッキの有無と鋼中水
素濃度と水素チャージ時間の関係を示す図である。FIG. 4 is a diagram showing the relationship between the presence or absence of Ni plating after hydrogen charging, the hydrogen concentration in steel, and the hydrogen charging time.
１ 切欠き ２ 金属鉄鋼片 ３ 金属鉄鋼片 ４ 切欠き ５ 電解水素チャージ装置 ６ 電解液 ７ 電解槽 ８ 白金電極 ９ 白金電極 １０ コントローラー １１ 温度センサ １２ ヒータ １３ 液面センサ １４ 送液ポンプ １５ 蒸留水タンク １６ ポテンショスッタット １７ 底部 DESCRIPTION OF SYMBOLS 1 Notch 2 Metal iron and steel piece 3 Metal iron and steel piece 4 Notch 5 Electrolytic hydrogen charging device 6 Electrolyte solution 7 Electrolyte tank 8 Platinum electrode 9 Platinum electrode 10 Controller 11 Temperature sensor 12 Heater 13 Liquid level sensor 14 Liquid feed pump 15 Distilled water tank 16 Potentiostat 17 Bottom
Claims (2)
欠き部近傍に選択的に水素を導入し、該材料中の水素濃
度を３ｐｐｍ以上とし、ついで該材料表面にＮｉ電解メ
ッキして該材料を液体窒素中に保存した後、その材料を
破断することを特徴とする金属材料の粒界破面の現出方
法。1. The method according to claim 1, wherein hydrogen is selectively introduced into the vicinity of the notch of the metallic steel material by an electrolytic hydrogen charging method, the hydrogen concentration in the material is adjusted to 3 ppm or more, and Ni surface is electroplated with Ni. A method for producing a grain boundary fracture surface of a metal material, comprising breaking the material after storing the material in liquid nitrogen.
て該切欠き部に水素をチャージする電解水素チャージ装
置であって、微量の亜砒素酸ナトリウムを含む０．５〜
３Ｎの硫酸溶液である電解液を含む電解槽と、電解液の
温度を一定に保つ温度制御手段と、電解液量を一定に保
つ自動定量送液手段と、陰電極である金属鉄鋼材料の切
欠き部近傍に対峙して設置される陽電極と、該陰電極お
よび陽電極に電解電圧を印荷する電源とからなる電解水
素チャージ装置。2. An electrolytic hydrogen charging apparatus for charging a hydrogen to said notch portion by using a metal steel slab having a notch portion as a negative electrode, wherein said device contains a small amount of sodium arsenite.
An electrolytic cell containing an electrolytic solution of a 3N sulfuric acid solution, temperature control means for keeping the temperature of the electrolytic solution constant, automatic quantitative liquid sending means for keeping the amount of the electrolytic solution constant, and cutting of a metallic steel material as a negative electrode An electrolytic hydrogen charging device comprising: a positive electrode installed facing the notch portion; and a power supply for applying an electrolytic voltage to the negative electrode and the positive electrode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24372397A JP3427691B2 (en) | 1997-09-09 | 1997-09-09 | Appearance method and apparatus of metal material grain boundary fracture surface |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24372397A JP3427691B2 (en) | 1997-09-09 | 1997-09-09 | Appearance method and apparatus of metal material grain boundary fracture surface |
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| Publication Number | Publication Date |
|---|---|
| JPH1183707A true JPH1183707A (en) | 1999-03-26 |
| JP3427691B2 JP3427691B2 (en) | 2003-07-22 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012159486A (en) * | 2011-02-03 | 2012-08-23 | Nippon Telegr & Teleph Corp <Ntt> | Hydrogen embrittlement prediction method |
| JP2012255655A (en) * | 2011-06-07 | 2012-12-27 | Nippon Steel & Sumitomo Metal | Method for preparing intergranular fracture specimen of steel material |
| KR101316420B1 (en) * | 2011-10-04 | 2013-10-08 | 주식회사 포스코 | Hydrogen treating device for analysis of hydrogen brittleness of steel member |
-
1997
- 1997-09-09 JP JP24372397A patent/JP3427691B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012159486A (en) * | 2011-02-03 | 2012-08-23 | Nippon Telegr & Teleph Corp <Ntt> | Hydrogen embrittlement prediction method |
| JP2012255655A (en) * | 2011-06-07 | 2012-12-27 | Nippon Steel & Sumitomo Metal | Method for preparing intergranular fracture specimen of steel material |
| KR101316420B1 (en) * | 2011-10-04 | 2013-10-08 | 주식회사 포스코 | Hydrogen treating device for analysis of hydrogen brittleness of steel member |
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| Publication number | Publication date |
|---|---|
| JP3427691B2 (en) | 2003-07-22 |
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