JPH0672838B2 - Corrosion fatigue life prediction method - Google Patents
Corrosion fatigue life prediction methodInfo
- Publication number
- JPH0672838B2 JPH0672838B2 JP62045353A JP4535387A JPH0672838B2 JP H0672838 B2 JPH0672838 B2 JP H0672838B2 JP 62045353 A JP62045353 A JP 62045353A JP 4535387 A JP4535387 A JP 4535387A JP H0672838 B2 JPH0672838 B2 JP H0672838B2
- Authority
- JP
- Japan
- Prior art keywords
- pit
- corrosion
- surface diameter
- depth
- critical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000007797 corrosion Effects 0.000 title claims description 48
- 238000005260 corrosion Methods 0.000 title claims description 48
- 238000000034 method Methods 0.000 title claims description 12
- 230000000977 initiatory effect Effects 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 6
- 230000035882 stress Effects 0.000 description 5
- 230000006866 deterioration Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000003745 diagnosis Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002431 foraging effect Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000013077 target material Substances 0.000 description 1
Landscapes
- Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)
- Investigating And Analyzing Materials By Characteristic Methods (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は腐食環境中で使用される機器の腐食疲労寿命予
測手法に関する。The present invention relates to a method for predicting corrosion fatigue life of equipment used in a corrosive environment.
機器安全運転に対する信頼性確保のためには、使用途中
検査により劣化の進行度合を調査して余寿命予測を行な
い使用限界を把握しておくことが望ましい。ところが一
般的に疲労破壊現象は劣化程度が調査判定できるような
前兆現象を伴なわずに破壊に至ることが多く、経年劣化
診断法が確立していない。In order to ensure the reliability for safe operation of equipment, it is desirable to investigate the progress of deterioration by in-use inspection to predict the remaining life and to grasp the usage limit. However, in general, fatigue failure often leads to failure without a precursory phenomenon such that the degree of deterioration can be investigated and judged, and a method for aging deterioration diagnosis has not been established.
経年劣化度の調査可能な前提条件としては、現象のメカ
ニズムに基づいた評価パラメータが存在するとともに、
それが調査計測可能な量であることが必要であるが、こ
のようなパラメータは未だ把握されておらず、従つてこ
れまでに腐食疲労寿命予測法が確立されていなかつた。As a prerequisite for investigating the degree of deterioration over time, there are evaluation parameters based on the mechanism of the phenomenon, and
It is necessary that the amount be surveyable and measurable, but such parameters have not yet been grasped, and thus a corrosion fatigue life prediction method has not been established so far.
本発明は上記従来技術の水準に鑑み、疲労破壊の一つの
形態である腐食疲労破壊に対してメカニズムに基づいた
計測可能な評価パラメータを用い全く新規な腐食疲労寿
命予測法を提供しようとするものである。In view of the level of the prior art described above, the present invention intends to provide a completely new method for predicting corrosion fatigue life by using measurable evaluation parameters based on mechanism for corrosion fatigue fracture which is one form of fatigue fracture. Is.
本発明者は疲労破壊のうち腐食疲労破壊については腐食
ピットが発生、成長し、ある限界条件（限界ピット条
件）に達すると腐食ピットを核としてき裂が発生し、き
裂成長の後破壊に至るというメカニズムを明らかにし
た。そこで本発明は腐食疲労破壊の前兆現象として腐食
ピットの成長挙動に着目し、本発明の腐食疲労き裂発生
余寿命予測法を完成した。Regarding the corrosion fatigue fracture among the fatigue fractures, the present inventor has found that a corrosion pit is generated and grows, and when a certain limit condition (limit pit condition) is reached, a crack is generated with the corrosion pit as a nucleus, and a crack is generated after the crack growth. The mechanism of reaching has been clarified. Therefore, the present invention has focused on the growth behavior of corrosion pits as a precursory phenomenon of corrosion fatigue fracture, and completed the method for predicting corrosion fatigue crack initiation remaining life of the present invention.
即ち、本発明は、下記（１）〜（４）の工程、 （１）目的とする実機部材において、使用時間t1（添字
の１は、任意の測定点を意味する）後の腐食ピット寸法
（深さa1，表面径2C1）を計測し、この値から腐食ピッ
ト寸法（深さa,表面径2C）と時間ｔの関係線を求める工
程、 （２）目的とする実機部材の材料定数である限界応力拡
大係数範囲（ΔＫ）ｐ、実機部材のピット発生部に加わ
る振動応力σａ及び上記（１）で得たピット深さa1及び
ピット表面径2C1を次式に代入し、き裂の発生する限界
腐食ピット寸法（限界腐食ピット深さap，限界腐食ピッ
ト表面径2Cp）を求める工程、 式中、Ｑ＝１＋1.464×(a1/C1)1.65 2Cp＝2C1×(ap/a1) （３）限界腐食寸法ap又は2Cpを上記（１）の腐食ピッ
ト寸法と時間の関係線に代入し、き裂寿命t2を求める工
程、 （４）き裂寿命t2から使用時間t1を差し引き、き裂発生
寿命を求める工程、よりなることを特徴とする腐食疲労
寿命予測法である。That is, in the present invention, in the following steps (1) to (4), (1) in a target actual machine member, a corrosion pit size after a usage time t 1 (subscript 1 means an arbitrary measurement point) (Depth a 1 , surface diameter 2C 1 ) is measured, and the relationship line between the corrosion pit dimensions (depth a, surface diameter 2C) and time t is calculated from these values. (2) Target material material Substituting the critical stress intensity factor range (ΔK) p which is a constant, the vibration stress σ a applied to the pit generation part of the actual machine member, the pit depth a 1 and the pit surface diameter 2C 1 obtained in (1) above into the following equation , The step of obtaining the critical corrosion pit size (critical corrosion pit depth a p , critical corrosion pit surface diameter 2 C p ) at which cracks occur, In the formula, Q = 1 + 1.464 × (a 1 / C 1 ) 1.65 2C p = 2C 1 × (a p / a 1 ) (3) Critical corrosion dimension a p or 2C p is the corrosion pit dimension in (1) above. Corrosion characterized by the following steps: Substituting into the relational line between time and time to obtain the crack life t 2 ; (4) Subtracting the operating time t 1 from the crack life t 2 to obtain the crack initiation life This is a fatigue life prediction method.
腐食ピット成長に基づきき裂発生余寿命を予測するに
は、（１）腐食ピットの成長法則、（２）腐食ピットか
らき裂が発生する限界条件を求める必要がある。以下、
これらについて詳述する。In order to predict the life of crack initiation based on the growth of corrosion pits, it is necessary to obtain (1) the law of growth of corrosion pits and (2) the critical conditions for crack initiation from corrosion pits. Less than,
These will be described in detail.
（１）腐食ピット成長則について、 第１図に腐食ピットの模式図を示す。ピット表面径を2C
とすると、腐食ピット成長則は、 2C＝α・ｔβ（α，β；実験により求められる定数,t;
時間） （１）式 で与えられる。βは通常1/3で鉄鋼材料の例でも、2C＝
9.7×10-2t1/3で表わされているが、このβはαと共に
材料、環境の組合せで実験的に求めておく方がよい。(1) Corrosion pit growth law FIG. 1 shows a schematic view of corrosion pits. 2C pit surface diameter
Then, the corrosion pit growth law is 2C = α · tβ (α, β; constants obtained by experiments, t;
Time) It is given by equation (1). β is usually 1/3, even in the case of steel materials, 2C =
It is expressed as 9.7 × 10 -2 t1 / 3, but it is better to experimentally determine β with α in combination with the material and environment.
（２）限界ピット条件について 限界ピット条件は腐食ピットをき裂とみなして破壊力学
パラメータである応力拡大係数範囲△Ｋによつて表示さ
れる材料定数であり、(△K)pで表示される。(2) Limiting pit condition The limiting pit condition is a material constant displayed according to the stress intensity factor range ΔK which is a fracture mechanics parameter by regarding the corrosion pit as a crack, and is displayed as (ΔK) p. .
腐食ピットからき裂が発生する条件は、第１図のように
表面径2C、深さａの腐食ピットに振動応力σａが負荷さ
れる時に下式で計算した△Ｋが △Ｋ(ΔK)p となつた時である。As shown in Fig. 1, when the vibration stress σ a is applied to a corrosion pit with a surface diameter of 2C and a depth of a, as shown in Fig. 1, ΔK calculated by the following formula is ΔK (ΔK) p It was a time when
ここで である。here Is.
ピット深さに対する限界ピット寸法apは△Ｋ＝△Kpとし
て得られapは（２）式より となる。The limit pit size a p with respect to the pit depth is obtained as ΔK = ΔK p , and a p is calculated from equation (2). Becomes
またピット表面径に対する限界ピット寸法2Cpは、ピッ
トが相似的形状で成長すると仮定して、調査時点のピッ
ト形状（表面径2C1，深さa1）を用いて、 2Cp＝2C1×ap／a1 （４）式 として得られる。ここにおいてapは前記（３）式で表わ
されるものである。The limit pit size 2C p to the pit surface diameter is 2C p = 2C 1 × using the pit shape (surface diameter 2C 1 , depth a 1 ) at the time of the survey, assuming that the pits grow in a similar shape. a p / a 1 (4) is obtained as equation. Here, a p is represented by the above formula (3).
第２図は、鉄鋼材料についての、振動応力σａ（kg/m
m2）に対する限界ピット条件（ΔＫ）ｐ（kgmm-3/2）の
関係を示したものである。（ΔＫ）ｐは実験データであ
るため、図のようにばらつきがあるが、評価に使用する
ときには、目的に応じて、例えば下限包絡線や中心線を
使用することができる。Fig. 2 shows the vibration stress σ a (kg / m for steel materials.
shows the relationship between the marginal pits condition (ΔK) p (kgmm -3/2) for m 2). Since (ΔK) p is experimental data, there are variations as shown in the figure, but when used for evaluation, for example, a lower limit envelope or center line can be used according to the purpose.
上記の腐食ピット成長則及び限界ピット表面径寸法条件
を用いて腐食ピット成長に基づく余寿命予測法を第３図
によつて説明する。第３図の横軸は時間（10gt）、縦軸
は腐食ピット表面径（10g2c）である。The remaining life prediction method based on the growth of corrosion pits using the above-mentioned law of growth of corrosion pits and the condition of the size of the limit pit surface diameter will be described with reference to FIG. In FIG. 3, the horizontal axis represents time (10gt), and the vertical axis represents corrosion pit surface diameter (10g2c).
ある時刻t1で腐食ピットの表面径の調査を行う。その時
の腐食ピットの表面径が図中の○印であつたとすると、
前述した腐食ピット成長則の（１）式によるグラフを○
印を通るように画く。At a certain time t 1 , the surface diameter of the corrosion pit is investigated. If the surface diameter of the corrosion pit at that time is marked with a circle in the figure,
The graph from the equation (1) of the above-mentioned corrosion pit growth law is
Draw as if going through the mark.
このグラフが１である。This graph is 1.
一方腐食ピットから、き裂が発生するピット表面径に対
する限界寸法を表わす前記（４）式によるグラフを画
く。このグラフが２である。On the other hand, from the corrosion pit, draw a graph according to the equation (4) that represents the critical dimension with respect to the pit surface diameter at which a crack occurs. This graph is 2.
腐食ピットの表面径2Cの将来成長予測線１と限界ピット
寸法２の交叉する点（図中☆印で時刻t2）でき裂が発生
することになり、ここでき裂発生余寿命は時刻t1より
（t2−t1）時間で与えられる。Future growth prospects line 1 and a point crossing the critical pit size 2 can (figure ☆ time a sign t 2) Cracks surface diameter 2C corrosion pits will be occur, where possible crack initiation remaining lifetime is the time t 1 Is given in (t 2 −t 1 ) time.
なお、以上の説明は腐食ピットの表面径2Cに着目してな
されたものであるが、腐食ピット深さａに着目しても同
様の効果が得られる。Although the above description was made by focusing on the surface diameter 2C of the corrosion pit, the same effect can be obtained by focusing on the depth a of the corrosion pit.
本発明方法により従来困難であつた腐食疲労寿命予測が
可能となり機器の信頼性確保が図れる。The method of the present invention makes it possible to predict the corrosion fatigue life, which has been difficult in the past, and to secure the reliability of the equipment.
第１図は腐食ピットの概略図、第２図は限界ピット条件
の実験例を示す図表、第３図は本発明の腐食疲労寿命予
測法の一実施態様を説明するための図表である。FIG. 1 is a schematic diagram of a corrosion pit, FIG. 2 is a diagram showing an experimental example of critical pit conditions, and FIG. 3 is a diagram for explaining one embodiment of a corrosion fatigue life prediction method of the present invention.
Claims (1)
食ピット寸法（深さa1，表面径2C1）を計測し、この値
から腐食ピット寸法（深さa,表面径2C）と時間ｔの関係
線を求める工程、 （２）目的とする実機部材の材料定数である限界応力拡
大係数範囲（ΔＫ）ｐ、実機部材のピット発生部に加わ
る振動応力σａ及び上記（１）で得たピット深さa1及び
ピット表面径2C1を次式に代入し、き裂の発生する限界
腐食ピット寸法（限界腐食ピット深さap，限界腐食ピッ
ト表面径2Cp）を求める工程、 式中、Ｑ＝１＋1.464×(a1/C1)1.65 2Cp＝2C1×(ap/a1) （３）限界腐食寸法ap又は2Cpを上記（１）の腐食ピッ
ト寸法と時間の関係線に代入し、き裂寿命t2を求める工
程、 （４）き裂寿命t2から使用時間t1を差し引き、き裂発生
余寿命を求める工程、 よりなることを特徴とする腐食疲労寿命予測法。1. The following steps (1) to (4), (1) measuring the corrosion pit dimensions (depth a 1 , surface diameter 2C 1 ) after a usage time t 1 in a target actual machine member, From this value, the process of obtaining the relationship line between the corrosion pit size (depth a, surface diameter 2C) and time t, (2) Limit stress intensity factor range (ΔK) p , which is the material constant of the target actual machine member, actual machine member Substituting the oscillating stress σ a applied to the pit generation part of No. 1 and the pit depth a 1 and the pit surface diameter 2C 1 obtained in (1) above into the following equation, the critical corrosion pit size (critical corrosion pit depth is a p, limit corrosion pit surface diameter 2C p) obtaining a, In the formula, Q = 1 + 1.464 × (a 1 / C 1 ) 1.65 2C p = 2C 1 × (a p / a 1 ) (3) Critical corrosion dimension a p or 2C p is the corrosion pit dimension in (1) above. To obtain a crack life t 2 by substituting it into a relational line of (4) and (4) subtracting the operating time t 1 from the crack life t 2 and obtaining a crack initiation remaining life. Corrosion fatigue life prediction method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62045353A JPH0672838B2 (en) | 1987-03-02 | 1987-03-02 | Corrosion fatigue life prediction method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62045353A JPH0672838B2 (en) | 1987-03-02 | 1987-03-02 | Corrosion fatigue life prediction method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63212844A JPS63212844A (en) | 1988-09-05 |
| JPH0672838B2 true JPH0672838B2 (en) | 1994-09-14 |
Family
ID=12716912
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62045353A Expired - Lifetime JPH0672838B2 (en) | 1987-03-02 | 1987-03-02 | Corrosion fatigue life prediction method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0672838B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103913393A (en) * | 2014-04-17 | 2014-07-09 | 南通大学 | Method for quickly calculating steel stress corrosion cracking time applicable to ocean engineering |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2796809B2 (en) * | 1988-08-27 | 1998-09-10 | 株式会社竹中工務店 | Concrete press-in method |
| JPH07119755B2 (en) * | 1989-10-06 | 1995-12-20 | 株式会社日立製作所 | Simple deterioration determination method and device |
| CN106202906B (en) * | 2016-07-06 | 2018-10-09 | 北京航空航天大学 | A kind of Corrosion Fatigue Properties characterization and life estimation method |
| CN109477786A (en) * | 2016-07-19 | 2019-03-15 | 艺康美国股份有限公司 | Controlling Industrial Water Treatment with Digital Imaging |
| CN109477802A (en) | 2016-07-19 | 2019-03-15 | 艺康美国股份有限公司 | Controlling Industrial Water Treatment with Digital Imaging |
| CN114491764B (en) * | 2022-02-14 | 2025-07-25 | 太原理工大学 | Steel member analysis method considering corrosion pit evolution method |
-
1987
- 1987-03-02 JP JP62045353A patent/JPH0672838B2/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103913393A (en) * | 2014-04-17 | 2014-07-09 | 南通大学 | Method for quickly calculating steel stress corrosion cracking time applicable to ocean engineering |
| CN103913393B (en) * | 2014-04-17 | 2016-03-09 | 南通大学 | The quick projectional technique of a kind of Marine Engineering Steel stress corrosion crack time |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63212844A (en) | 1988-09-05 |
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