JP6724761B2

JP6724761B2 - Hydrogen embrittlement evaluation apparatus, hydrogen embrittlement evaluation method, and test piece used therein

Info

Publication number: JP6724761B2
Application number: JP2016243898A
Authority: JP
Inventors: 宏太富松
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 2016-06-08
Filing date: 2016-12-16
Publication date: 2020-07-15
Anticipated expiration: 2036-12-16
Also published as: JP2017223639A

Description

本発明は、水素脆性評価装置および水素脆性評価方法ならびにそれに用いられる試験片に関する。 TECHNICAL FIELD The present invention relates to a hydrogen embrittlement evaluation apparatus, a hydrogen embrittlement evaluation method, and a test piece used therein.

高強度鋼、ニッケル合金またはチタン合金等の金属材料では、環境から侵入した水素により破壊が生じることが知られている（水素脆化）。特に、実用上は、水素侵入から一定時間経過した後に生じる水素脆化（遅れ破壊）が問題となっている。このときの破壊形態は、結晶粒界での破壊となる場合がある。また、介在物などの第２相と母相との境界（異相界面）が破壊起点になる場合も報告されている。 It is known that hydrogen invades from the environment in metallic materials such as high-strength steel, nickel alloys, and titanium alloys (hydrogen embrittlement). In particular, in practical use, hydrogen embrittlement (delayed fracture) that occurs after a certain time has elapsed from the hydrogen penetration has become a problem. The fracture mode at this time may be fracture at the crystal grain boundary. It has also been reported that the boundary (different phase interface) between the second phase such as inclusions and the parent phase serves as the fracture starting point.

したがって、耐水素脆化性を向上させるには、個々の結晶粒界または異相界面の、剥離強度および剥離が生じるまでの経過時間（剥離寿命）に及ぼす水素の影響を評価する技術が必要とされている。なお、以下の説明において、結晶粒界（双晶界面等を含む。）および異相界面等の金属組織内に現れる境界面を総称して、「ミクロ組織界面」ということがある。 Therefore, in order to improve the hydrogen embrittlement resistance, a technique for evaluating the effect of hydrogen on the peel strength and the elapsed time until peeling (peeling life) of individual grain boundaries or heterophasic interfaces is required. ing. In the following description, the boundary surfaces appearing in the metal structure such as crystal grain boundaries (including twin crystal interfaces) and different phase interfaces may be collectively referred to as “microstructure interface”.

例えば、特許文献１には、引張試験片に張力を加えるステップと、電解質を含む水溶液の中に前記張力を加えた引張試験片を対極と共に配置して、該引張試験片に負の電位を付与するステップと、前記水溶液の電解にて発生する水素により、前記引張試験片が水素脆化するのを待つステップと、を含むことを特徴とする耐遅れ破壊性の評価方法が開示されている。 For example, in Patent Document 1, a step of applying tension to a tensile test piece and a tensile test piece to which the tension is applied are arranged in an aqueous solution containing an electrolyte together with a counter electrode, and a negative potential is applied to the tensile test piece. And a step of waiting for the tensile test piece to become hydrogen embrittlement due to hydrogen generated by the electrolysis of the aqueous solution, the method for evaluating delayed fracture resistance is disclosed.

また、特許文献２には、水素イオンを含む電解溶液の満たされた電解槽と、電流発生手段と、定荷重発生手段とを有する装置を用い、長手方向に平行部を有する試験片を電解槽に貫通させ、該試験片の電解槽外にはみ出した両端部を連結治具を介して定荷重発生手段に固定し、電流発生手段により電気化学的に水素チャージをしながら、定荷重発生手段により引張応力を負荷して、該試験片の破断応力を測定することを特徴とする薄鋼板の耐水素脆化特性評価方法が開示されている。 Further, in Patent Document 2, an apparatus having an electrolytic cell filled with an electrolytic solution containing hydrogen ions, an electric current generating means, and a constant load generating means is used, and a test piece having a parallel portion in a longitudinal direction is electrolyzed. The test piece is fixed to the constant load generating means via a connecting jig, while the current generating means is electrochemically charged with hydrogen, while the constant load generating means is used. Disclosed is a method for evaluating hydrogen embrittlement resistance of a thin steel sheet, which comprises applying a tensile stress and measuring the breaking stress of the test piece.

さらに、特許文献３には、ｐＨが３以上の溶液の満たされた溶液槽と、定荷重発生手段とを有する装置を用い、長手方向に平行部を有する試験片を溶液槽に貫通させ、該試験片の溶液槽外にはみ出した両端部を連結治具を介して定荷重発生手段に固定し、定荷重発生手段により引張応力を負荷して、該試験片が破断する破断応力を測定することを特徴とする薄鋼板の耐水素脆化特性評価方法が開示されている。 Further, in Patent Document 3, a device having a solution tank filled with a solution having a pH of 3 or more and a constant load generating means is used, and a test piece having a parallel portion in the longitudinal direction is passed through the solution tank, Fix both ends of the test piece protruding out of the solution tank to the constant load generating means via a connecting jig, apply a tensile stress by the constant load generating means, and measure the breaking stress at which the test piece breaks. A method for evaluating hydrogen embrittlement resistance of a thin steel sheet is disclosed.

そして、特許文献４には、電解液を保持する電解槽と、鋼材に負荷する変形応力を発生する定荷重発生手段と、鋼材に水素チャージを行うための電流を発生する電流発生手段からなる実験装置を用いて、定荷重発生手段に設置した鋼材に変形応力を負荷しない状態で、電解液中で電流発生手段により少なくとも鋼材中の水素量が一定になるまで電気化学的に水素チャージを行った後、水素チャージを続けながら定荷重発生手段により試験材に引張強度未満の変形応力を負荷して一定時間保持し、破断しなかった場合は、以後、さらに変形応力を増加させて一定時間保持する工程を、破断するまで順次行うことを特徴とする水素脆化特性評価方法が開示されている。 Then, in Patent Document 4, an experiment comprising an electrolytic cell for holding an electrolytic solution, a constant load generating means for generating a deformation stress to be applied to a steel material, and a current generating means for generating an electric current for hydrogen-charging the steel material Using the device, hydrogen was electrochemically charged in the electrolytic solution until the amount of hydrogen in the steel material became constant at least by the current generating means in the state where no deformation stress was applied to the steel material installed in the constant load generating means. After that, while continuing hydrogen charging, the test material is loaded with a deformation stress less than the tensile strength by the constant load generation means and held for a certain period of time. Disclosed is a method for evaluating hydrogen embrittlement characteristics, which comprises sequentially performing steps until fracture.

特開２００４−３０９１９７号公報JP, 2004-309197, A 特開２０１３−１２４９９８号公報JP, 2013-124998, A 特開２０１３−１２４９９９号公報JP, 2013-124999, A 特開２０１６−５７１６３号公報JP, 2016-57163, A

しかしながら、特許文献１〜４に記載の方法は、いずれもマクロスケールでの引張試験であるため、試験片全体での平均的な情報しか得られず、個々のミクロ組織界面における剥離強度および剥離寿命を評価することはできない。 However, since the methods described in Patent Documents 1 to 4 are all tensile tests on a macro scale, only average information on the entire test piece can be obtained, and the peel strength and the peel life at each microstructure interface are obtained. Can not be evaluated.

本発明は、上記の問題を解決し、ミクロ組織界面の剥離強度および剥離寿命に及ぼす水素の影響を評価することが可能な水素脆性評価装置および水素脆性評価方法ならびにそれに用いられる試験片を提供することを目的とする。 The present invention solves the above problems and provides a hydrogen embrittlement evaluation apparatus and a hydrogen embrittlement evaluation method capable of evaluating the effect of hydrogen on the peel strength and the peel life of a microstructure interface, and a test piece used therefor. The purpose is to

本発明は、上記の問題を解決するためになされたものであり、下記の水素脆性評価装置および水素脆性評価方法ならびにそれに用いられる試験片を要旨とする。 The present invention has been made in order to solve the above problems, and has as its gist a hydrogen embrittlement evaluation apparatus, a hydrogen embrittlement evaluation method, and a test piece used for the same.

（１）固定端から自由端に向かって一方向に延びる微小片持ち梁が形成された試験片の水素脆化特性を評価する装置であって、
前記試験片は、前記微小片持ち梁の前記固定端と前記自由端との間を通り、かつ、前記一方向に略垂直なミクロ組織界面を少なくとも１つ有し、
前記微小片持ち梁は、前記ミクロ組織界面のうちの１つより自由端側に、前記１つのミクロ組織界面側を向く係止面を有し、
前記微小片持ち梁を電解液に浸漬する電解液槽と、
前記電解液に浸漬される対極と、
前記試験片と前記対極との間に電位差を生じさせる外部電源と、
前記係止面に対して、前記一方向と略平行な方向に荷重を負荷する探針と、
前記探針の変位および荷重を測定する測定部と、を備える、
水素脆性評価装置。 (1) A device for evaluating hydrogen embrittlement characteristics of a test piece on which a minute cantilever beam extending in one direction from a fixed end to a free end is formed,
The test piece passes through between the fixed end and the free end of the microcantilever, and has at least one microstructure interface substantially perpendicular to the one direction,
The microcantilever has a locking surface facing the one microstructure interface side on the free end side of one of the microstructure interfaces,
An electrolyte bath in which the microcantilever is immersed in an electrolyte,
A counter electrode immersed in the electrolytic solution,
An external power supply that causes a potential difference between the test piece and the counter electrode,
A probe that applies a load in a direction substantially parallel to the one direction with respect to the locking surface,
A measuring unit for measuring the displacement and load of the probe,
Hydrogen brittleness evaluation device.

（２）前記微小片持ち梁が有する面と前記１つのミクロ組織界面との交線の少なくとも一部に沿って切欠きが形成されている、
上記（１）に記載の水素脆性評価装置。 (2) A notch is formed along at least a part of a line of intersection between the surface of the microcantilever and the one microstructure interface.
The apparatus for evaluating hydrogen embrittlement according to (1) above.

（３）前記微小片持ち梁が有する面と前記１つのミクロ組織界面との交線が露出するように、前記微小片持ち梁が有する面上に強化膜が形成されている、
上記（１）または（２）に記載の水素脆性評価装置。 (3) A reinforcing film is formed on the surface of the microcantilever so that the line of intersection between the surface of the microcantilever and the one microstructure interface is exposed.
The hydrogen embrittlement evaluation apparatus according to (1) or (2) above.

（４）前記試験片に前記微小片持ち梁が複数形成され、
各微小片持ち梁を通る前記１つのミクロ組織界面が同一である、
上記（１）から（３）までのいずれかに記載の水素脆性評価装置。 (4) A plurality of the minute cantilever beams are formed on the test piece,
The one microstructure interface through each microcantilever is the same,
The hydrogen embrittlement evaluation apparatus according to any one of (1) to (3) above.

（５）前記電解液槽が、底部に貫通孔を有し、前記貫通孔の裏面を囲繞するシール材を介して、前記試験片の表面の上に載せられ、前記微小片持ち梁を電解液に浸漬する、
上記（１）から（４）までのいずれかに記載の水素脆性評価装置。 (5) The electrolytic solution tank has a through hole at the bottom, and is placed on the surface of the test piece via a sealing material that surrounds the back surface of the through hole, and the microcantilever is used as an electrolytic solution. Soak in,
The hydrogen embrittlement evaluation apparatus according to any one of (1) to (4) above.

（６）前記試験片の温度を調整する温度調整部をさらに備える、
上記（１）から（５）までのいずれかに記載の水素脆性評価装置。 (6) A temperature adjusting unit for adjusting the temperature of the test piece is further provided.
The hydrogen embrittlement evaluation apparatus according to any one of (1) to (5) above.

（７）試験片の水素脆化特性を評価する方法であって、
（ａ）固定端から自由端に向かって一方向に延びる微小片持ち梁を、前記試験片が有するミクロ組織界面のうちの少なくとも１つが前記固定端と前記自由端との間を通り、かつ、前記少なくとも１つの前記ミクロ組織界面が前記一方向に略垂直となるように形成する工程と、
（ｂ）前記微小片持ち梁の、前記ミクロ組織界面のうちの１つより自由端側に、前記１つのミクロ組織界面側を向く係止面を形成する工程と、
（ｃ）前記微小片持ち梁を電解液に浸漬する工程と、
（ｄ）前記試験片と、前記電解液に浸漬される対極との間に電位差を生じさせて、前記微小片持ち梁に電気化学的に水素を導入する工程と、
（ｅ）探針を用いて、前記係止面に対して、前記一方向と略平行な方向に荷重を負荷する工程と、
（ｆ）前記探針の変位および荷重を測定する工程と、を備える、
水素脆性評価方法。 (7) A method for evaluating hydrogen embrittlement characteristics of a test piece,
(A) a microcantilever which extends in one direction from a fixed end to a free end, at least one of microstructure interfaces of the test piece passes between the fixed end and the free end, and Forming the at least one microstructure interface to be substantially perpendicular to the one direction;
(B) forming a locking surface facing the one microstructure interface side on the free end side of one of the microstructure interfaces of the micro cantilever,
(C) a step of immersing the microcantilever in an electrolytic solution,
(D) a step of causing a potential difference between the test piece and a counter electrode immersed in the electrolytic solution to electrochemically introduce hydrogen into the microcantilever.
(E) a step of applying a load to the locking surface in a direction substantially parallel to the one direction using a probe,
(F) measuring the displacement and load of the probe,
Hydrogen embrittlement evaluation method.

（８）前記（ａ）の工程において、前記微小片持ち梁が有する面と前記１つのミクロ組織界面との交線の少なくとも一部に沿って切欠きを形成する、
上記（７）に記載の水素脆性評価方法。 (8) In the step (a), a notch is formed along at least a part of a line of intersection between the surface of the microcantilever and the one microstructure interface.
The method for evaluating hydrogen embrittlement according to (7) above.

（９）前記（ａ）の工程において、前記微小片持ち梁が有する面と前記１つのミクロ組織界面との交線が露出するように、前記微小片持ち梁が有する面上に強化膜を形成する、
上記（７）または（８）に記載の水素脆性評価方法。 (9) In the step (a), a reinforcing film is formed on the surface of the micro cantilever so that the line of intersection between the surface of the micro cantilever and the one microstructure interface is exposed. To do
The method for evaluating hydrogen embrittlement according to (7) or (8) above.

（１０）前記（ａ）の工程において、複数の微小片持ち梁を、各微小片持ち梁を通る前記１つのミクロ組織界面が同一となるように形成する、
上記（７）から（９）までのいずれかに記載の水素脆性評価方法。 (10) In the step (a), a plurality of microcantilever beams are formed such that the one microstructure interface passing through each microcantilever is the same.
The method for evaluating hydrogen embrittlement according to any of (7) to (9) above.

（１１）前記複数の微小片持ち梁のうちの一の微小片持ち梁について、前記（ａ）〜（ｆ）の工程を経て測定された変位および荷重と、
前記複数の微小片持ち梁のうちの他の微小片持ち梁について、前記（ａ）、（ｂ）、（ｅ）および（ｆ）の工程によって測定された変位および荷重とを比較して、
試験片の水素脆化特性を評価する、
上記（１０）に記載の水素脆性評価方法。 (11) Displacement and load measured through the steps (a) to (f) for one micro cantilever among the plurality of micro cantilevers,
Comparing the displacement and load measured by the steps (a), (b), (e) and (f) of the other micro cantilever among the plurality of micro cantilevers,
Evaluate the hydrogen embrittlement characteristics of the test piece,
The method for evaluating hydrogen embrittlement according to (10) above.

（１２）前記複数の微小片持ち梁のうちの一の微小片持ち梁について、前記（ａ）〜（ｆ）の工程によって測定された変位および荷重と、
前記複数の微小片持ち梁のうちの他の微小片持ち梁について、前記（ａ）〜（ｃ）、（ｅ）および（ｆ）の工程によって測定された変位および荷重とを比較して、
試験片の水素脆化特性を評価する、
上記（１０）または（１１）に記載の水素脆性評価方法。 (12) Displacement and load measured by the steps (a) to (f) for one micro cantilever among the plurality of micro cantilevers,
For other micro-cantilever beams among the plurality of micro-cantilever beams, the displacement and load measured by the steps (a) to (c), (e) and (f) are compared,
Evaluate the hydrogen embrittlement characteristics of the test piece,
The method for evaluating hydrogen embrittlement according to (10) or (11) above.

（１３）前記探針の前記変位を制御することによって、試験片の水素脆化特性を評価する、上記（７）から（１２）までのいずれかに記載の水素脆性評価方法。 (13) The hydrogen embrittlement evaluation method according to any one of (7) to (12) above, wherein the hydrogen embrittlement property of the test piece is evaluated by controlling the displacement of the probe.

（１４）前記探針の前記荷重を制御することによって、試験片の水素脆化特性を評価する、上記（７）から（１２）までのいずれかに記載の水素脆性評価方法。 (14) The hydrogen embrittlement evaluation method according to any one of (7) to (12) above, wherein the hydrogen embrittlement property of the test piece is evaluated by controlling the load of the probe.

（１５）固定端から自由端に向かって一方向に延びる微小片持ち梁が形成された試験片であって、
前記微小片持ち梁の前記固定端と前記自由端との間を通り、かつ、前記一方向に略垂直なミクロ組織界面を少なくとも１つ有し、
前記微小片持ち梁は、前記ミクロ組織界面のうちの１つより自由端側に、前記１つのミクロ組織界面側を向く係止面を有する、
試験片。 (15) A test piece having a minute cantilever beam extending in one direction from a fixed end to a free end,
Passing between the fixed end and the free end of the microcantilever, and having at least one microstructure interface substantially perpendicular to the one direction,
The microcantilever has a locking surface facing the one microstructure interface side on the free end side of one of the microstructure interfaces.
Test pieces.

（１６）前記微小片持ち梁が有する面と前記１つのミクロ組織界面との交線の少なくとも一部に沿って切欠きが形成されている、
上記（１５）に記載の試験片。 (16) A notch is formed along at least part of a line of intersection between the surface of the microcantilever and the one microstructure interface.
The test piece described in (15) above.

（１７）前記微小片持ち梁が有する面と前記１つのミクロ組織界面との交線が露出するように、前記微小片持ち梁が有する面上に強化膜が形成されている、
上記（１５）または（１６）に記載の試験片。 (17) A reinforcing film is formed on the surface of the microcantilever so that the intersection line between the surface of the microcantilever and the one microstructure interface is exposed.
The test piece according to (15) or (16) above.

（１８）前記微小片持ち梁が複数形成され、
各微小片持ち梁を通る前記１つのミクロ組織界面が同一である、
上記（１５）から（１７）までのいずれかに記載の試験片。 (18) A plurality of the minute cantilever beams are formed,
The one microstructure interface through each microcantilever is the same,
The test piece according to any one of (15) to (17) above.

本発明によれば、結晶粒界または異相界面等の境界面における剥離強度および剥離寿命に及ぼす水素の影響を評価することができる。 According to the present invention, it is possible to evaluate the influence of hydrogen on the peel strength and the peel life at the boundary surface such as a grain boundary or a heterophase interface.

本発明の一実施形態に係る水素脆性評価装置の一例を模式的に示した図である。It is the figure which showed typically an example of the hydrogen embrittlement evaluation apparatus which concerns on one Embodiment of this invention. 本発明の一実施形態に係る微小片持ち梁および探針を模式的に示した図である。It is the figure which showed typically the microcantilever and the probe which concern on one Embodiment of this invention. 切欠きの形状の一例を模式的に示した図である。It is the figure which showed typically an example of the shape of a notch. 探針の形状の一例を模式的に示した図である。It is the figure which showed typically an example of the shape of a probe. 荷重と変位との関係を模式的に示した図である。It is the figure which showed typically the relationship between load and displacement. 荷重および変位の時間変化を示す図である。It is a figure which shows the time change of a load and displacement. 実施例において、試験片の表面に加工した微小片持ち梁の寸法を示した図である。It is a figure showing a size of a minute cantilever beam processed into a surface of a test piece in an example. 水素導入下で測定されたＮｉ−Ｃｒ合金およびＳＵＳ３１６Ｌ鋼の荷重と剥離時間との関係を示した図である。It is the figure which showed the relationship of the load of Ni-Cr alloy and SUS316L steel measured under hydrogen introduction, and peeling time.

添付した図面を参照して、本発明の一実施形態に係る水素脆性評価装置およびそれを用いた評価方法について、詳細に説明する。 A hydrogen embrittlement evaluation apparatus and an evaluation method using the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

図１は、本発明の一実施形態に係る水素脆性評価装置１００の一例を模式的に示した図である。また、図２に微小片持ち梁１０の形状を模式的に示す。本発明の一実施形態に係る水素脆性評価装置１００は、固定端１０ａから自由端１０ｂに向かって一方向（図２中におけるＹ方向）に延びる微小片持ち梁１０が形成された試験片１の水素脆化特性を評価する装置である。試験片１の材質については特に制限は設けず、例えば、鋼材、合金材等を用いることができる。 FIG. 1 is a diagram schematically showing an example of a hydrogen embrittlement evaluation apparatus 100 according to an embodiment of the present invention. Further, FIG. 2 schematically shows the shape of the micro cantilever 10. A hydrogen embrittlement evaluation apparatus 100 according to an embodiment of the present invention is a test piece 1 having a micro cantilever 10 extending in one direction (Y direction in FIG. 2) from a fixed end 10a to a free end 10b. This is an apparatus for evaluating hydrogen embrittlement characteristics. The material of the test piece 1 is not particularly limited, and, for example, a steel material, an alloy material or the like can be used.

図１に示すように、水素脆性評価装置１００は、電解液槽２と対極３と外部電源４と探針５と測定部６とを備える。すなわち、本発明の一実施形態に係る評価方法では、上述の微小片持ち梁１０を形成し（工程ａ）、微小片持ち梁１０に係止面１０ｃを形成した後（工程ｂ）、微小片持ち梁１０を電解液槽２内の電解液２０に浸漬し（工程ｃ）、外部電源４を用いて試験片１と対極３との間に電位差を生じさせて、微小片持ち梁１０に電気化学的に水素を導入した状態において（工程ｄ）、係止面１０ｃに対して、探針５でＹ方向と略平行な方向に荷重を負荷し（工程ｅ）、探針５の変位および荷重を測定部６によって測定する（工程ｆ）ことによって、試験片の水素脆化特性を評価することが可能である。各構成要素について以下に詳しく説明する。 As shown in FIG. 1, the hydrogen embrittlement evaluation apparatus 100 includes an electrolytic solution tank 2, a counter electrode 3, an external power source 4, a probe 5, and a measuring unit 6. That is, in the evaluation method according to the embodiment of the present invention, the above-mentioned micro cantilever beam 10 is formed (step a), and after the locking surface 10c is formed on the micro cantilever beam 10 (step b), the micro cantilever beam is formed. The cantilever 10 is immersed in the electrolytic solution 20 in the electrolytic solution tank 2 (step c), an electric potential difference is generated between the test piece 1 and the counter electrode 3 by using the external power source 4, and the micro cantilever 10 is electrically charged. In the state where hydrogen is chemically introduced (step d), a load is applied to the locking surface 10c by the probe 5 in a direction substantially parallel to the Y direction (step e), and the displacement and load of the probe 5 It is possible to evaluate the hydrogen embrittlement characteristics of the test piece by measuring (step f) with the measuring unit 6. Each component will be described in detail below.

図２に示すように、微小片持ち梁１０は、試験片１が有するミクロ組織界面１ｂが、固定端１０ａと自由端１０ｂとの間を１つ通り、かつ、ミクロ組織界面１ｂがＹ方向に略垂直となるように形成されている。試験片１が有するミクロ組織界面１ｂは、固定端１０ａと自由端１０ｂとの間に複数通っていてもよい。 As shown in FIG. 2, in the microcantilever 10, the microstructure interface 1b of the test piece 1 passes between the fixed end 10a and the free end 10b, and the microstructure interface 1b extends in the Y direction. It is formed so as to be substantially vertical. A plurality of microstructure interfaces 1b included in the test piece 1 may pass between the fixed end 10a and the free end 10b.

ここで、本発明における「ミクロ組織界面」とは、鋼材または合金材等の金属組織内に現れる不連続面を意味し、例えば、結晶粒界（双晶界面を含む。）、異相界面等が含まれる。 Here, the “microstructure interface” in the present invention means a discontinuous surface appearing in the metal structure of a steel material or an alloy material, and for example, a crystal grain boundary (including a twin crystal interface), a heterophase interface, and the like. included.

微小片持ち梁１０を形成する方法について特に制限はないが、例えば、レーザー加工、集束イオンビーム（ＦＩＢ）加工を用いることができる。また、微小片持ち梁１０の断面形状についても、特に制限は設けないが、上記の方法を用いて形成する場合、三角形または五角形にすると、加工時間を短縮できるため好ましい。 The method of forming the microcantilever 10 is not particularly limited, but for example, laser processing or focused ion beam (FIB) processing can be used. The cross-sectional shape of the microcantilever 10 is also not particularly limited, but when it is formed using the above method, a triangle or a pentagon is preferable because the processing time can be shortened.

微小片持ち梁１０の寸法についても制限は設けず、試験片１の結晶粒径または介在物等の第２相の大きさに応じた寸法とすることが好ましい。 The size of the microcantilever 10 is not limited, and it is preferable to set the size according to the crystal grain size of the test piece 1 or the size of the second phase such as inclusions.

そして、微小片持ち梁１０は、ミクロ組織界面１ｂより自由端１０ｂ側に、ミクロ組織界面１ｂ側を向く係止面１０ｃを有する。係止面１０ｃの形状については特に制限されず、図２に示す構成においては、微小片持ち梁１０の、ミクロ組織界面１ｂより自由端１０ｂ側に孔が形成され、当該孔の内周面のうち、ミクロ組織界面１ｂ側を向く面が係止面１０ｃとなる。図２に示す構成では、微小片持ち梁１０に孔が形成されているがこれに限定されず、例えば、微小片持ち梁１０の自由端１０ｂ側がフック形状になっていてもよい。 The microcantilever 10 has a locking surface 10c facing the microstructure interface 1b side on the free end 10b side of the microstructure interface 1b. The shape of the locking surface 10c is not particularly limited. In the configuration shown in FIG. 2, a hole is formed in the micro cantilever 10 on the free end 10b side of the microstructure interface 1b, and the inner peripheral surface of the hole is formed. Of these, the surface facing the microstructure interface 1b side is the locking surface 10c. In the configuration shown in FIG. 2, the micro cantilever 10 has holes formed therein, but the present invention is not limited to this. For example, the free end 10b side of the micro cantilever 10 may have a hook shape.

また、図２に示すように、引張試験の際にミクロ組織界面１ｂでの剥離が生じやすくなるように、微小片持ち梁１０が有する２つの側面１０ｄと１つのミクロ組織界面１ｂとの交線に沿って切欠き１０ｅが形成されていてもよい。なお、図２に示す構成では、切欠き１０ｅは、側面１０ｄに形成されているが、微小片持ち梁１０が有する面と１つのミクロ組織界面１ｂとの交線の少なくとも一部に沿って形成されていればよい。 In addition, as shown in FIG. 2, in order to facilitate peeling at the microstructure interface 1b during a tensile test, an intersection line between the two side surfaces 10d of the microcantilever 10 and one microstructure interface 1b. The notch 10e may be formed along the line. In the configuration shown in FIG. 2, the notch 10e is formed on the side surface 10d, but is formed along at least a part of the line of intersection between the surface of the microcantilever 10 and one microstructure interface 1b. It should have been done.

切欠き１０ｅの形状について特に制限は設けないが、図３に示すような矩形（ａ）には角部が２つ存在しミクロ組織界面１ｂ以外の位置に応力が集中してしまうという問題がある。そのため、ミクロ組織界面１ｂの位置に一点だけ応力の集中部を持つＵ字形状（ｂ）またはＶ字形状（ｃ）とすることが好ましい。 Although the shape of the notch 10e is not particularly limited, there is a problem that the rectangle (a) as shown in FIG. 3 has two corners and stress concentrates at a position other than the microstructure interface 1b. .. Therefore, it is preferable to have a U-shape (b) or V-shape (c) having a stress concentration portion at only one point at the position of the microstructure interface 1b.

さらに、引張試験の際にミクロ組織界面１ｂ以外の部位で剥離が生じるのを防止するために、微小片持ち梁１０が有する面と１つのミクロ組織界面１ｂとの交線が露出するように、微小片持ち梁１０が有する面上に強化膜が形成されていてもよい。 Further, in order to prevent peeling from occurring in a portion other than the microstructure interface 1b during the tensile test, the line of intersection between the surface of the microcantilever 10 and one microstructure interface 1b is exposed, A reinforcing film may be formed on the surface of the microcantilever 10.

強化膜を形成する方法について特に制限はないが、例えば、以下に示すようなＦＩＢを用いた方法を採用することができる。まず、強化膜の原料となる化合物ガスを微小片持ち梁１０が有する面上に導入する。その状態で、ＦＩＢのイオンビームを面上に照射すると面上から二次電子が発生し、化合物ガスを固体成分と気体成分に分解する。その後、分解した固体成分は、イオンビームの照射領域に堆積する。 The method for forming the reinforcing film is not particularly limited, but for example, a method using FIB as shown below can be adopted. First, a compound gas, which is a raw material for the reinforcing film, is introduced onto the surface of the microcantilever 10. When the surface is irradiated with the ion beam of FIB in that state, secondary electrons are generated from the surface, and the compound gas is decomposed into a solid component and a gas component. After that, the decomposed solid component is deposited on the ion beam irradiation region.

なお、上記の方法を用いる場合、強化膜を金属にすると、電解液中で試験片と金属強化膜との間で腐食（ガルバニック腐食）が生じるため好ましくない。そのため、強化膜を形成する場合には、絶縁体の膜を用いる必要があり、例えば、シリコン酸化物を用いることが好ましい。その場合には、化合物ガスとして、（ＨＳｉＣＨ_３Ｏ）_４またはＣ_６Ｈ_２４Ｏ_６Ｓｉ_６を用いることとなる。 When the above method is used, if the reinforcing film is made of metal, corrosion (galvanic corrosion) occurs between the test piece and the metal reinforcing film in the electrolytic solution, which is not preferable. Therefore, when forming the reinforcing film, it is necessary to use an insulating film, and for example, silicon oxide is preferably used. In that case, as the compound gas, and the use of (HSiCH ₃ _{O) 4} or _{_{_{_{C 6 H 24 O 6 Si 6}}}} .

また、蒸着によって強化膜を形成してもよい。その場合には、蒸着によって微小片持ち梁１０が有する面上の全体に強化膜を形成した後、レーザー加工、ＦＩＢ加工等を施すことによって、微小片持ち梁１０が有する面と１つのミクロ組織界面１ｂとの交線を露出させることができる。 Further, the reinforcing film may be formed by vapor deposition. In that case, after forming a reinforced film on the entire surface of the microcantilever 10 by vapor deposition, laser processing, FIB processing, etc. are performed to form a microstructure and a surface of the microcantilever 10. The line of intersection with the interface 1b can be exposed.

電解液槽２は、微小片持ち梁１０を電解液２０に浸漬し、微小片持ち梁１０に電気化学的に水素を導入するためのものである。電解液槽２の構造について特に制限はないが、図１に示すように、底部に貫通孔２ａを有し、貫通孔２ａの裏面を囲繞するシール材２ｂを介して、試験片１の表面１ａの上に載せられ、微小片持ち梁１０を電解液２０に浸漬する構成とすることができる。 The electrolytic solution tank 2 is for immersing the micro cantilever 10 in the electrolytic solution 20 and electrochemically introducing hydrogen into the micro cantilever 10. The structure of the electrolytic solution tank 2 is not particularly limited, but as shown in FIG. 1, the surface 1a of the test piece 1 has a through hole 2a at the bottom and a sealing material 2b surrounding the back surface of the through hole 2a. It is possible to adopt a configuration in which the micro-cantilever 10 is placed on top of and is immersed in the electrolytic solution 20.

対極３は、電解液２０に浸漬されている。そして、外部電源４を用いて試験片１と対極３との間に電位差を生じさせ、試験片１を対極３に対して負電位にすることによって、微小片持ち梁１０に電気化学的に水素を導入する。対極３の材質について特に制限はないが、例えば白金を用いることができる。 The counter electrode 3 is immersed in the electrolytic solution 20. Then, a potential difference is generated between the test piece 1 and the counter electrode 3 by using the external power source 4, and the test piece 1 is made to have a negative potential with respect to the counter electrode 3, so that the minute cantilever 10 is electrochemically hydrogenated. To introduce. The material of the counter electrode 3 is not particularly limited, but platinum can be used, for example.

図１に示すように、必要に応じて、参照極７を対極３とともに電解液２０に浸漬させてもよい。対極３のみでは電流制御でしか微小片持ち梁１０に水素を導入できないが、参照極７を用いることによって、電位制御でも水素を導入することが可能となる。 As shown in FIG. 1, the reference electrode 7 together with the counter electrode 3 may be immersed in the electrolytic solution 20 as necessary. Although it is possible to introduce hydrogen into the minute cantilever beam 10 only by controlling the current with only the counter electrode 3, it is possible to introduce hydrogen by controlling the potential by using the reference electrode 7.

試験片１、対極３および参照極７はそれぞれ導線４０を介して外部電源４に接続されている。水素の導入を電位制御で行う場合には、外部電源４にポテンショスタットを用いる。一方、水素の導入を電流制御で行う場合には、外部電源４にガルバノスタットを用い、参照極７は省略する。 The test piece 1, the counter electrode 3, and the reference electrode 7 are each connected to the external power source 4 via the conductor wire 40. When hydrogen is introduced by potential control, a potentiostat is used as the external power source 4. On the other hand, when introducing hydrogen by current control, a galvanostat is used as the external power source 4 and the reference electrode 7 is omitted.

そして、探針５を用いて微小片持ち梁１０に荷重を負荷することによって、引張試験を実施する。ミクロ組織界面１ｂにおける剥離強度および剥離寿命を評価することを目的としているため、微小片持ち梁１０の係止面１０ｃに対して、Ｙ方向と略平行な方向に荷重を負荷する。これにより、ミクロ組織界面１ｂに圧縮応力およびせん断応力が付与されるのを極力制限しつつ、引張応力が作用する微小引張試験を実施することが可能となる。そのため、探針５は図示しない駆動装置によってＸ方向、Ｙ方向およびＺ方向への移動が可能な構造となっている。 Then, a tensile test is performed by applying a load to the micro cantilever 10 using the probe 5. Since the purpose is to evaluate the peel strength and the peel life at the microstructure interface 1b, a load is applied to the locking surface 10c of the microcantilever 10 in a direction substantially parallel to the Y direction. This makes it possible to carry out a micro-tensile test in which tensile stress acts while limiting the application of compressive stress and shear stress to the microstructure interface 1b as much as possible. Therefore, the probe 5 has a structure capable of moving in the X direction, the Y direction, and the Z direction by a driving device (not shown).

探針５の先端形状について特に制限はないが、例えば、図４に示すように先端が円柱状の探針（ａ）、開き角が６０°以下の円錐形状の探針（ｂ）、稜線の１つがＺ方向と略平行な三角錐形状の探針（ｃ）、または先端が六角柱状の探針（ｄ）を用いることができる。また、探針５の材質についても特に制限はないが、引張試験の際にたわんだり屈曲したりしないような硬い材質であることが好ましく、例えば、ダイヤモンド製またはセラミックス製の探針を用いることができる。 The shape of the tip of the probe 5 is not particularly limited, but for example, as shown in FIG. 4, a probe having a cylindrical tip (a), a conical probe having an opening angle of 60° or less (b), a ridge line A triangular pyramid-shaped probe (c), one of which is substantially parallel to the Z direction, or a hexagonal column-shaped probe (d) can be used. The material of the probe 5 is not particularly limited, but it is preferable that the probe 5 is a hard material that does not bend or bend during the tensile test. For example, a diamond or ceramic probe is used. it can.

また、探針５が微小片持ち梁１０の係止面１０ｃの位置を探し出す機能を有する構成を備えていてもよい。具体的には、Ｚ方向の荷重を一定にしたまま、探針５で微小片持ち梁１０の面上を走査し、Ｚ方向の位置を記録することで、表面の凹凸像を取得できる。そして、取得された凹凸像より、精確に係止面１０ｃの位置を検出することが可能になる。上記の構成を実現するためには、図４（ｅ）に示すように、探針５の先端が錐状であることが好ましい。 Further, the probe 5 may have a configuration having a function of finding the position of the locking surface 10c of the micro cantilever 10. Specifically, while the load in the Z direction is kept constant, the probe 5 scans the surface of the minute cantilever beam 10 and records the position in the Z direction, whereby an uneven image of the surface can be obtained. Then, it becomes possible to accurately detect the position of the locking surface 10c from the obtained uneven image. In order to realize the above configuration, it is preferable that the tip of the probe 5 has a conical shape, as shown in FIG.

引張試験の際の探針５の変位および荷重は、測定部６によって測定される。そして、得られた荷重−変位曲線に基づき、ミクロ組織界面１ｂの剥離強度および剥離寿命に及ぼす水素の影響を評価する。 The displacement and load of the probe 5 during the tensile test are measured by the measuring unit 6. Then, based on the obtained load-displacement curve, the effect of hydrogen on the peel strength and the peel life of the microstructure interface 1b is evaluated.

図５は、測定される荷重−変位関係を模式的に示す図であり、図６は、荷重および変位の時間変化を示す図である。ミクロ組織界面１ｂの剥離強度を評価する場合、引張試験は変位制御を採用する。即ち、図５に示すように荷重を測定しながら所定の速度で探針を変位させる。ミクロ組織界面１ｂが剥離すると荷重が低下するため、破断荷重Ｐｃまたは変位ΔＬから、水素環境中のミクロ組織界面１ｂの剥離強度を評価することができる。 FIG. 5 is a diagram schematically showing the measured load-displacement relationship, and FIG. 6 is a diagram showing changes over time in load and displacement. When evaluating the peel strength of the microstructure interface 1b, displacement control is adopted in the tensile test. That is, as shown in FIG. 5, the probe is displaced at a predetermined speed while measuring the load. Since the load decreases when the microstructure interface 1b is peeled off, the peel strength of the microstructure interface 1b in the hydrogen environment can be evaluated from the breaking load Pc or the displacement ΔL.

一方、ミクロ組織界面１ｂの剥離寿命を評価する場合、引張試験は荷重制御を採用する。即ち、図６に示すように一定値の荷重を負荷した状態で圧子の変位を測定し、変位に急激または不連続な増加が生じた時点で、ミクロ組織界面で剥離が発生したと判断することができる。このように、荷重を負荷してから剥離が生じるまでの経過時間Δｔから、水素環境中のミクロ組織界面１ｂの剥離寿命を評価することができる。 On the other hand, when evaluating the peeling life of the microstructure interface 1b, load control is adopted in the tensile test. That is, as shown in FIG. 6, the displacement of the indenter is measured under a load of a constant value, and when the displacement suddenly or discontinuously increases, it is judged that delamination has occurred at the microstructure interface. You can In this way, the delamination life of the microstructure interface 1b in a hydrogen environment can be evaluated from the elapsed time Δt from when a load is applied until delamination occurs.

なお、本発明の一実施形態に係る装置は、試験片１の温度を調整する図示しない温度調整部をさらに備えていてもよい。温度調整部を備えることによって、全ての実験において温度を同一として、実験条件を揃えたり、または、温度を変えて種々の実験を繰り返すことによって、ミクロ組織界面１ｂの剥離強度および剥離寿命に及ぼす温度の影響を評価したりすることが可能となる。 The apparatus according to the embodiment of the present invention may further include a temperature adjusting unit (not shown) that adjusts the temperature of the test piece 1. By providing a temperature adjusting unit, the temperature is the same in all experiments, the experimental conditions are made uniform, or various experiments are repeated by changing the temperature so that the temperature affects the peel strength and the peel life of the microstructure interface 1b. It is possible to evaluate the effect of.

試験片１の表面１ａには、微小片持ち梁１０が複数形成されていてもよい。複数の微小片持ち梁１０について上記の引張試験を実施することによって、例えば、同一の実験を複数回実施した場合における結果のばらつきを調査して分析精度の検証を行ったり、または、異なる環境下での試験結果を比較することで、水素の影響をより詳細に評価したりすることが可能となる。複数の微小片持ち梁１０を形成する場合には、実験条件を統一するため、各微小片持ち梁１０を通るミクロ組織界面１ｂが同一の境界面となるようにすることが好ましい。 A plurality of minute cantilever beams 10 may be formed on the surface 1 a of the test piece 1. By performing the above-described tensile test on a plurality of minute cantilever beams 10, for example, the variation in the results when the same experiment is performed a plurality of times is investigated to verify the analysis accuracy, or under different environments. By comparing the test results in 1., it becomes possible to evaluate the effect of hydrogen in more detail. When a plurality of micro cantilever beams 10 are formed, it is preferable that the microstructure interfaces 1b passing through the micro cantilever beams 10 have the same boundary surface in order to unify the experimental conditions.

例えば、上記のように複数の微小片持ち梁を形成した場合においては、そのうちの１つの微小片持ち梁については、電解液に浸漬し水素を導入した状態（上記の工程ａ〜ｆを経た状態）で引張試験を実施し、他の微小片持ち梁については、大気中（上記の工程ａ、ｂ、ｅおよびｆを経た状態）または電解液に浸漬するだけで水素を導入しない状態（上記の工程ａ〜ｃ、ｅおよびｆを経た状態）で引張試験を実施し、それぞれの試験で測定された変位および荷重を比較することによって試験片の水素脆化特性をより詳細に評価することが可能となる。 For example, in the case where a plurality of micro cantilevers are formed as described above, one micro cantilever among them is in a state of being immersed in an electrolytic solution and introducing hydrogen (a state after the above steps a to f). ), and for other microcantilever beams, in the atmosphere (after the above steps a, b, e, and f) or in the state of not introducing hydrogen only by immersing in the electrolytic solution (above It is possible to evaluate the hydrogen embrittlement characteristics of the test piece in more detail by performing a tensile test in steps a to c, e and f) and comparing the displacement and load measured in each test. Becomes

以下、実施例によって本発明をより具体的に説明するが、本発明はこれらの実施例に限定されるものではない。 Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to these examples.

表１の化学組成（質量％）と引張強度とを有するＮｉ−Ｃｒ合金およびＳＵＳ３１６Ｌ鋼を試験材として、ＦＩＢ加工により微小片持ち梁を作製した。そして、Ｎｉ−Ｃｒ合金はランダム粒界に、ＳＵＳ３１６Ｌ鋼は双晶界面について、剥離強度に及ぼす水素の影響を評価した。また、微小片持ち梁は、同じミクロ組織界面（ランダム粒界、双晶界面）に複数個用意した。微小片持ち梁の寸法を図７に示す。そして、ミクロ組織界面より自由端側に、円形の孔を設けた。また、微小片持ち梁の断面形状は五角形とし、ミクロ組織界面にはＵ字状の切欠きを付与した。 Using the Ni-Cr alloy and SUS316L steel having the chemical composition (mass%) and the tensile strength shown in Table 1 as test materials, microcantilever beams were produced by FIB processing. Then, the effect of hydrogen on the peel strength was evaluated for the Ni—Cr alloy at random grain boundaries and for the twin interface of SUS316L steel. A plurality of microcantilever beams were prepared at the same microstructure interface (random grain boundary, twin interface). The dimensions of the micro cantilever are shown in FIG. Then, a circular hole was provided on the free end side of the microstructure interface. Further, the cross-sectional shape of the micro cantilever was pentagonal, and a U-shaped notch was provided at the microstructure interface.

探針には、稜線の１つがＺ方向と略平行なダイヤモンド製の三角錐探針を用いた。そして三角錐探針で微小片持ち梁の表面を走査し、円形の穴の位置を探し出した。探針の向きは、引張試験の際にＺ方向と略平行な稜線が微小片持ち梁の係止面に接触するように調整した。探針は最大５μｍまで０．１７μｍ／ｓの速度で水平移動させ、この間の水平方向の変位と荷重とを記録した。測定は大気中と陰極水素チャージ中とで実施し、試験温度は室温とした。 As the probe, a triangular pyramid probe made of diamond with one of its ridge lines substantially parallel to the Z direction was used. Then, the surface of the micro cantilever was scanned with the triangular pyramid probe to find the position of the circular hole. The orientation of the probe was adjusted so that the ridge line substantially parallel to the Z direction would contact the locking surface of the microcantilever during the tensile test. The probe was moved horizontally up to 5 μm at a speed of 0.17 μm/s, and the horizontal displacement and load during this time were recorded. The measurement was carried out in the atmosphere and during cathode hydrogen charging, and the test temperature was room temperature.

試験片への水素の導入は電解液に白金の対極を浸漬することで行った。電解液にはホウ酸緩衝液（ｐＨ：８．６）を用い、触媒毒のチオシアン酸アンモニウムを３ｇ／Ｌ添加した。電流密度は５．１Ａ／ｍ^２とし、電流制御で水素を導入した。また、試験片全体に均一に水素をチャージするため、引張試験の前に１８００ｓの予備水素チャージを実施した。 Hydrogen was introduced into the test piece by immersing the counter electrode of platinum in the electrolytic solution. A borate buffer solution (pH: 8.6) was used as the electrolytic solution, and 3 g/L of ammonium thiocyanate as a catalyst poison was added. The current density was 5.1 A/m ^2, and hydrogen was introduced by current control. Further, in order to uniformly charge the entire test piece with hydrogen, preliminary hydrogen charging was performed for 1800 seconds before the tensile test.

表２に測定された破断荷重を示す。ＳＵＳ３１６Ｌ鋼の破断荷重は大気中と水素中とでほぼ変わらず、破断荷重比（（水素中の破断荷重）÷（大気中の破断荷重））は０．９５７となった。一方、Ｎｉ−Ｃｒ合金は、水素により破断荷重が顕著に低下し、破断荷重比は０．２５２となった。これらの結果よりＳＵＳ３１６Ｌ鋼の双晶界面の剥離強度は水素により低下せず、一方、Ｎｉ−Ｃｒ合金のランダム粒界の剥離強度は水素により大きく低下することが示唆された。本発明により、水素環境下のミクロ組織界面の剥離強度を評価可能であることが確認された。 Table 2 shows the measured breaking load. The breaking load of SUS316L steel was almost the same in the atmosphere and in hydrogen, and the breaking load ratio ((breaking load in hydrogen)/(breaking load in atmosphere)) was 0.957. On the other hand, the breaking load of Ni-Cr alloy was remarkably reduced by hydrogen, and the breaking load ratio was 0.252. From these results, it was suggested that the peel strength at the twin interface of SUS316L steel was not lowered by hydrogen, while the peel strength at the random grain boundary of Ni—Cr alloy was significantly lowered by hydrogen. According to the present invention, it was confirmed that the peel strength at the microstructure interface in a hydrogen environment can be evaluated.

実施例１と同様に、表１の化学組成（質量％）と引張強度とを有するＮｉ−Ｃｒ合金およびＳＵＳ３１６Ｌ鋼を試験材として、図７に示す形状を有する微小片持ち梁を作製した。また、探針についても実施例１と同一のものを用いた。そして、探針のＺ方向と略平行な稜線が微小片持ち梁の係止面に接触するように調整し、微小引張試験片を引張り、弾性応力を負荷し保持した。 Similarly to Example 1, a Ni-Cr alloy having the chemical composition (mass %) and tensile strength shown in Table 1 and SUS316L steel were used as test materials to fabricate a microcantilever having the shape shown in FIG. Also, the same probe as in Example 1 was used. Then, the ridgeline substantially parallel to the Z direction of the probe was adjusted so as to contact the locking surface of the microcantilever, and the microtensile test piece was pulled and elastic stress was applied and held.

弾性応力の値は、弾性限界の３０％、６０％、または９０％とし、保持時間は最長で７２００ｓとした。応力を保持している間、探針の水平方向の変位を逐次記録した。測定は大気中および水素環境中において、室温で行った。水素環境中の測定では、陰極水素チャージ開始後、１８００ｓ経過した後に微小引張試験片に応力を負荷した。試験片への水素の導入は電解液に白金の対極を浸漬することで行った。電解液にはホウ酸緩衝液（ｐＨ：８．６）を用い、触媒毒のチオシアン酸アンモニウムを３ｇ／Ｌ添加した。電流密度は５．１Ａ／ｍ^２とし、電流制御で水素を導入した。 The value of elastic stress was 30%, 60%, or 90% of the elastic limit, and the maximum holding time was 7200 s. The horizontal displacement of the probe was sequentially recorded while the stress was retained. The measurement was performed at room temperature in the atmosphere and hydrogen environment. In the measurement in a hydrogen environment, stress was applied to the micro tensile test piece 1800 seconds after the start of cathode hydrogen charging. Hydrogen was introduced into the test piece by immersing the counter electrode of platinum in the electrolytic solution. A borate buffer solution (pH: 8.6) was used as the electrolytic solution, and 3 g/L of ammonium thiocyanate as a catalyst poison was added. The current density was 5.1 A/m ^2, and hydrogen was introduced by current control.

図８に、水素環境中での剥離寿命を示す。ＳＵＳ３１６Ｌの双晶界面は、いずれの弾性応力においても、応力負荷から７２００ｓ以内に剥離は認められなかった。一方、Ｎｉ−Ｃｒ合金のランダム粒界は、弾性限界の６０％および９０％の応力において７２００ｓ以内に剥離が認められた。 FIG. 8 shows the stripping life in a hydrogen environment. At the elastic interface of SUS316L, no peeling was observed within 7200 s from the stress load at any elastic stress. On the other hand, at the random grain boundaries of the Ni-Cr alloy, peeling was recognized within 7200 s at the stresses of 60% and 90% of the elastic limit.

また、図示してはいないが、大気中では、ＳＵＳ３１６Ｌの双晶界面もＮｉ−Ｃｒ合金のランダム粒界も、７２００ｓ以内に剥離は認められなかった。これより、ＳＵＳ３１６Ｌの双晶界面は、遅れ破壊への寄与は低く、Ｎｉ−Ｃｒ合金のランダム粒界は遅れ破壊への寄与が高いことが判明した。本発明により、個々のミクロ組織界面に対し、水素環境下での剥離寿命を評価できることが確認された。 Although not shown in the drawing, neither peeling of the twin interface of SUS316L nor the random grain boundary of the Ni—Cr alloy was observed within 7200 s in the atmosphere. From this, it was found that the twin interface of SUS316L has a low contribution to delayed fracture, and the random grain boundaries of the Ni—Cr alloy have a high contribution to delayed fracture. According to the present invention, it was confirmed that the peeling life in a hydrogen environment can be evaluated for each microstructure interface.

１．試験片
１ａ．表面
１ｂ．ミクロ組織界面
２．電解液槽
２ａ．貫通孔
２ｂ．シール材
３．対極
４．外部電源
５．探針
６．測定部
７．参照極
１０．微小片持ち梁
１０ａ．固定端
１０ｂ．自由端
１０ｃ．係止面
１０ｄ．側面
１０ｅ．切欠き
２０．電解液
４０．導線
１００．水素脆性評価装置
1. Test piece 1a. Surface 1b. Microstructure interface 2. Electrolyte bath 2a. Through hole 2b. Seal material 3. Counter electrode 4. External power supply 5. Probe 6. Measuring unit 7. Reference electrode 10. Micro cantilever 10a. Fixed end 10b. Free end 10c. Locking surface 10d. Side 10e. Notch 20. Electrolyte solution 40. Lead wire 100. Hydrogen embrittlement evaluation device

Claims

A device for evaluating hydrogen embrittlement characteristics of a test piece on which a minute cantilever beam extending in one direction from a fixed end to a free end is formed,
The test piece passes through between the fixed end and the free end of the microcantilever, and has at least one microstructure interface substantially perpendicular to the one direction,
The microcantilever has a locking surface facing the one microstructure interface side on the free end side of one of the microstructure interfaces,
An electrolyte bath in which the microcantilever is immersed in an electrolyte,
A counter electrode immersed in the electrolytic solution,
An external power supply that causes a potential difference between the test piece and the counter electrode,
A probe that applies a load in a direction substantially parallel to the one direction with respect to the locking surface,
A measuring unit for measuring the displacement and load of the probe,
Hydrogen brittleness evaluation device.

A notch is formed along at least a part of a line of intersection between the surface of the microcantilever and the one microstructure interface.
The hydrogen embrittlement evaluation apparatus according to claim 1.

A reinforcing film is formed on the surface of the microcantilever so that the line of intersection between the surface of the microcantilever and the one microstructure interface is exposed.
The hydrogen embrittlement evaluation device according to claim 1 or 2.

A plurality of the minute cantilever beams are formed on the test piece,
The one microstructure interface through each microcantilever is the same,
The hydrogen embrittlement evaluation device according to any one of claims 1 to 3.

The electrolytic solution tank has a through hole at the bottom and is placed on the surface of the test piece through a sealing material that surrounds the back surface of the through hole, and the microcantilever is immersed in the electrolytic solution. ,
The hydrogen embrittlement evaluation device according to any one of claims 1 to 4.

Further comprising a temperature adjusting unit for adjusting the temperature of the test piece,
The hydrogen embrittlement evaluation device according to any one of claims 1 to 5.

A method for evaluating hydrogen embrittlement characteristics of a test piece,
(A) a microcantilever which extends in one direction from a fixed end to a free end, at least one of microstructure interfaces of the test piece passes between the fixed end and the free end, and Forming the at least one microstructure interface to be substantially perpendicular to the one direction;
(B) forming a locking surface facing the one microstructure interface side on the free end side of one of the microstructure interfaces of the micro cantilever,
(C) a step of immersing the microcantilever in an electrolytic solution,
(D) a step of causing a potential difference between the test piece and a counter electrode immersed in the electrolytic solution to electrochemically introduce hydrogen into the microcantilever.
(E) a step of applying a load to the locking surface in a direction substantially parallel to the one direction using a probe,
(F) measuring the displacement and load of the probe,
Hydrogen embrittlement evaluation method.

In the step (a), a notch is formed along at least a part of a line of intersection between the surface of the microcantilever and the one microstructure interface.
The method for evaluating hydrogen embrittlement according to claim 7.

In the step (a), a reinforcing film is formed on the surface of the micro cantilever so that the line of intersection between the surface of the micro cantilever and the one microstructure interface is exposed.
The hydrogen embrittlement evaluation method according to claim 7.

In the step (a), a plurality of micro cantilevers are formed so that the one microstructure interface passing through each micro cantilever is the same.
The hydrogen embrittlement evaluation method according to any one of claims 7 to 9.

Displacement and load measured through the steps (a) to (f) for one micro cantilever among the plurality of micro cantilevers,
Comparing the displacement and load measured by the steps (a), (b), (e) and (f) of the other micro cantilever among the plurality of micro cantilevers,
Evaluate the hydrogen embrittlement characteristics of the test piece,
The hydrogen embrittlement evaluation method according to claim 10.

Displacement and load measured by the steps (a) to (f) for one of the plurality of micro-cantilever beams,
For other micro-cantilever beams among the plurality of micro-cantilever beams, the displacement and load measured by the steps (a) to (c), (e) and (f) are compared,
Evaluate the hydrogen embrittlement characteristics of the test piece,
The hydrogen embrittlement evaluation method according to claim 10 or 11.

The hydrogen embrittlement evaluation method according to any one of claims 7 to 12, wherein the hydrogen embrittlement property of the test piece is evaluated by controlling the displacement of the probe.

The hydrogen embrittlement evaluation method according to any one of claims 7 to 12, wherein the hydrogen embrittlement property of the test piece is evaluated by controlling the load of the probe.

A test piece having a minute cantilever beam extending in one direction from a fixed end to a free end,
Passing between the fixed end and the free end of the microcantilever, and having at least one microstructure interface substantially perpendicular to the one direction,
The microcantilever has a locking surface facing the one microstructure interface side on the free end side of one of the microstructure interfaces.
Test pieces.

A notch is formed along at least a part of a line of intersection between the surface of the microcantilever and the one microstructure interface.
The test piece according to claim 15.

A reinforcing film is formed on the surface of the microcantilever so that the line of intersection between the surface of the microcantilever and the one microstructure interface is exposed.
The test piece according to claim 15 or 16.

A plurality of the minute cantilever beams are formed,
The one microstructure interface through each microcantilever is the same,
The test piece according to any one of claims 15 to 17.