JP6371234B2 - Weld temperature estimation method - Google Patents

Description

  The present disclosure relates to a method for estimating a temperature of a weld.

  In heat exchangers used in thermal power plants, marine boilers, etc., heat transfer tubes made of different heat-resistant steel may be used depending on the temperature range from the viewpoint of higher efficiency and cost reduction. So-called dissimilar material welding, in which heat transfer tubes formed of different heat resistant steels are welded, is applied. For example, a low temperature region heat transfer tube formed of ferritic heat resistant steel and a high temperature region heat transfer tube formed of austenitic stainless steel may be welded with different materials. In the case where dissimilar material welding is applied, for example, a welded portion of a heat transfer tube formed of austenitic stainless steel and a heat transfer tube formed of ferritic chromium-molybdenum steel has a chromium- An Inconel-based welding material (a filler material) having a thermal expansion coefficient between that of molybdenum steel (Cr—Mo) and that of stainless steel (SUS) may be used.

JP 2012-137385 A

  By the way, according to the knowledge of the present inventor, in the heat exchanger operated for a long time in a high temperature environment, in the welded portion between the heat transfer tubes formed of different heat resistant steels, the heat affected zone of the weld metal and the base material and Separation may occur at the boundary portion (so-called bond portion), and vapor leakage may occur. For example, in a weld zone where a heat transfer tube made of chromium / molybdenum steel and a heat transfer tube made of austenitic stainless steel are welded via an inconel weld metal, the heat transfer tube made of chromium / molybdenum steel is used. As shown in FIGS. 10 and 11, peeling (hereinafter referred to as bond peeling) occurs at the boundary between the heat-affected zone of the base material of the heat tube and the Inconel-based weld metal, and steam leakage may occur. . For this reason, in order to investigate the cause of such bond peeling, it is necessary to accurately estimate the temperature of the weld.

  As a method of estimating the temperature of the heat transfer tube during the operation of the heat exchanger, there is a method of estimating the temperature based on the thickness of the steam oxidation scale formed on the inner peripheral surface of the heat transfer tube. However, in the vicinity of the bond portion, the steam oxide scale is easily peeled off due to the difference in thermal expansion between the base material of the heat transfer tube and the weld metal, so the steam oxide scale is not uniformly formed. Is difficult to estimate with high accuracy.

  In addition, Patent Document 1 relates to a heat transfer tube formed of high-strength ferritic steel having a bainite structure, and the bainite structure is destroyed by the increase in heating temperature or the elapse of heating time, and the Picker hardness of the heat transfer tube is reduced. The method of estimating the temperature of the heat exchanger tube at the time of operation | movement of a heat exchanger using is disclosed. In such a method, the hardness of the base material of the heat transfer tube deteriorated with time and the hardness of a plurality of aging materials are compared, and the Larson mirror parameter value is obtained from the hardness of the aging material corresponding to the hardness of the heat transfer tube. The temperature of the heat transfer tube is estimated by substituting the mirror parameter value into the relational expression of the Larson mirror parameter.

  However, the temperature estimation method described in Patent Document 1 estimates the temperature of the heat transfer tube during the operation of the heat exchanger based on the hardness of the base material portion of the heat transfer tube. It is not possible to accurately estimate the temperature at the welded portion between the heat transfer tubes formed of steel.

  This invention is made | formed in view of the conventional subject as mentioned above, Comprising: About the heat exchanger provided with the 1st heat exchanger tube and the 2nd heat exchanger tube formed with mutually different heat-resistant steel, it is the 1st at the time of operation. It is providing the temperature estimation method of the welding part which can estimate the temperature of the welding part of a heat exchanger tube and a 2nd heat exchanger tube accurately.

  (1) The temperature estimation method of the welding part which concerns on at least 1 embodiment of this invention is the temperature of the welding part which estimates the temperature at the time of operation in the welding part of the 1st heat exchanger tube with which a heat exchanger is provided, and a 2nd heat exchanger tube. In the estimation method, the first heat transfer tube is formed of a first heat resistant steel, the second heat transfer tube is formed of a second heat resistant steel different from the first heat resistant steel, and the first heat transfer tube and The second heat transfer tube is welded via a weld metal, and the hardness or thickness of the deteriorated layer generated in a portion of the weld metal adjacent to the heat affected zone of the base material of the first heat transfer tube. A measurement step of measuring, and an estimation step of estimating a temperature during operation of the welded portion based on the hardness or thickness of the deteriorated layer measured in the measurement step.

  As a result of intensive studies by the inventor of the present application, it has been clarified that a deteriorated layer is formed in the portion adjacent to the heat-affected zone of the base material of the first heat transfer tube in the weld metal as time passes. . This altered layer is harder than other regions, and has a different tissue state (for example, color) as viewed with a microscope or the like as compared with other regions. Further, it has been found that the hardness and thickness of the deteriorated layer depend on the temperature of the weld during operation of the heat exchanger.

  Then, the temperature estimation method of the weld part described in the above (1) measures the hardness or thickness of the deteriorated layer generated in the part adjacent to the heat affected part of the base material of the first heat transfer tube in the weld metal. A measurement step, and an estimation step for estimating a temperature during operation of the welded portion based on the hardness or thickness of the deteriorated layer measured in the measurement step. Thereby, based on the hardness or thickness of the deteriorated layer measured in the measurement step, the temperature during operation in the welded portion (dissimilar material joint portion) of the first heat transfer tube and the second heat transfer tube included in the heat exchanger is accurately measured. It can be estimated well.

(2) In some embodiments, the temperature estimation method according to (1) above, wherein the estimation step includes the hardness or thickness of the deteriorated layer measured in the measurement step, and the hardness of the deteriorated layer. And the information indicating the relationship between the weld metal Larson mirror parameter L and the weld metal Larson mirror parameter corresponding to the hardness or thickness of the deteriorated layer measured in the measurement step. and L ₁ derivation step of deriving the current value L _1, a temperature estimation step of the L ₁ on the basis of the current value L ₁ of the Larson-Miller parameter derived in the derivation step, to estimate the temperature during operation of the weld, including.

  According to the knowledge of the present inventor, the hardness of the deteriorated layer and the Larson mirror parameter L of the deposited metal have a correlation, and the hardness of the deteriorated layer increases as the Larson mirror parameter L increases. Further, according to the knowledge of the present inventors, there is a correlation between the thickness of the deteriorated layer and the Larson mirror parameter L of the deposited metal, and the thickness of the deteriorated layer increases as the Larson mirror parameter L increases.

Therefore, in the temperature estimation method according to (2), in L ₁ deriving step, the hardness or thickness of the measured in the measurement step affected layer, and the Larson-Miller parameter L of the hardness or thickness of the deposited metal deteriorated layer the information indicating the relationship, based on, and derives the current value L ₁ of Larson-Miller parameters of weld metal corresponding to the hardness or thickness of the measured in the measurement step altered layer. Then, based on the current value L ₁ of Larson-Miller parameters of weld metal derived by L ₁ derivation step, a temperature estimation step, the welded portion by using the relational expression of Larson-Miller parameter (Formula 1 and Formula 2 below) The temperature during operation is estimated. Thus, based on the current value L ₁ of Larson-Miller parameters of weld metal corresponding to the hardness or thickness of the measured in the measurement step deteriorated layer, the first heat transfer pipe and the second heat transfer tube heat exchanger comprises The temperature at the time of operation in a welded part (dissimilar material joint part) can be accurately estimated.

(3) In some embodiments, the temperature estimation method according to (2) above, wherein in the temperature estimation step, the current value L ₁ of the Larson mirror parameter derived in the L ₁ derivation step, an initial value L ₀ of the Larson-Miller parameter when unused weld metal, from said time unused weld metal and the elapsed time t ₁ to date, on the basis, estimates the temperature during operation of the weld.

According to the temperature estimation method according to (3), the current value L ₁ of Larson-Miller parameters of weld metal corresponding to the hardness or thickness of the measured in the measurement step affected layer of weld metal while not in use, an initial value L ₀ of the Larson-Miller parameter, the elapsed time t ₁ from when unused weld metal to date, on the basis of the weld using the relational expression of Larson-Miller parameter (formula 1 and formula 2 below) The temperature at the time of operation in the (dissimilar material joint part) can be accurately estimated.

(4) In some embodiments, the temperature estimation method according to the above (2) or (3), wherein the current value L ₁ of the Larson mirror parameter derived in the L ₁ deriving step, and the deposited metal unused an initial value L ₀ of the Larson Miller parameter during said from the time unused weld metal and the elapsed time t ₁ to date, on the basis, the weld metal in the temperature conditions during operation of the weld and the total life evaluation step of evaluating the entire lifetime t ₀ from when not in use to break of, on the basis of the said evaluated in all life evaluation step the entire service life t ₀ and the elapsed time t _1, the current of the weld metal And a remaining life evaluation step for evaluating a remaining life t ₂ (= t ₀ −t ₁ ) from the break to the break.

The temperature estimation method according to (4), the current value L ₁ of Larson-Miller parameters of weld metal corresponding to the hardness or thickness of the measured in the measurement step altered layer, when not in use of the deposited metal Larson Based on the initial value L ₀ of the mirror parameter and the elapsed time t ₁ from when the weld metal is not used to the present time, a welded portion is obtained by using Larson mirror parameter relational expressions (formulas 1 and 2 described later). It is possible to accurately evaluate the total life t ₀ from when the weld metal is not used until it breaks under the temperature condition during operation of the (dissimilar joint part). Further, by subtracting the elapsed time t ₁ from when the weld metal is not used to the present time from the total life t ₀ evaluated in the total life evaluation step, the remaining life t ₂ from the present time to the fracture of the weld metal in the weld zone is obtained. It can be obtained with high accuracy.

  (5) In some embodiments, the temperature estimation method according to any one of (1) to (4) above, wherein the weld metal is a Ni-based alloy.

  According to the knowledge of the present inventor, as described in (5) above, when a Ni-based alloy is used as the weld metal, the temperature estimation method according to any one of (1) to (4) above. Can be preferably used.

  (6) In some embodiments, the temperature estimation method according to (5) above, wherein the weld metal is Inconel (registered trademark).

  According to the knowledge of the inventor of the present application, as described in (6) above, when using Inconel as the weld metal, the temperature estimation method described in (5) above can be suitably used.

  (7) In some embodiments, in the temperature estimation method according to any one of (1) to (6), the first heat transfer tube is formed of a ferritic heat resistant steel.

  According to the knowledge of the present inventor, when the first heat transfer tube is formed of ferritic heat resistant steel as described in (7) above, any one of (1) to (6) above The described temperature estimation method can be suitably used.

  (8) In some embodiments, the temperature estimation method according to (7) above, wherein the first heat transfer tube is made of chromium-molybdenum steel.

  According to the inventor's knowledge, when the first heat transfer tube is formed of chromium-molybdenum steel as described in (8) above, the temperature estimation method described in (7) above is preferably used. can do.

  (9) In some embodiments, in the temperature estimation method according to any one of (1) to (8), the second heat transfer tube is formed of austenitic stainless steel.

  According to the knowledge of the present inventor, when the second heat transfer tube is formed of austenitic stainless steel as described in (9) above, any one of (1) to (8) above The described temperature estimation method can be suitably used.

  According to at least one embodiment of the present invention, for a heat exchanger comprising a first heat transfer tube and a second heat transfer tube formed of different heat resistant steels, the first heat transfer tube and the second heat transfer tube during operation There is provided a method for estimating the temperature of a welded portion, which can accurately estimate the temperature of the welded portion.

It is a perspective view which shows typically the welding part of the 1st heat exchanger tube with which a heat exchanger is provided, and a 2nd heat exchanger tube. For the welded portion between the first heat transfer tube and the second heat transfer tube shown in FIG. 1, the creep rupture test was conducted at a test temperature of 600 ° C. under a condition that the rupture time was about 1700 hours. It is a figure which shows a cross section (cross section along the axis | shaft of a 1st heat exchanger tube and a 2nd heat exchanger tube), and hardness distribution. For the welded portion between the first heat transfer tube and the second heat transfer tube shown in FIG. 1, the creep rupture test was conducted at a test temperature of 600 ° C. under a condition where the rupture time was about 40000 hours. It is a figure which shows a cross section (cross section along the axis | shaft of a 1st heat exchanger tube and a 2nd heat exchanger tube), and hardness distribution. It is a figure which shows the temperature estimation flow which estimates the temperature of the welding part at the time of operation | movement of a heat exchanger. It is a figure which shows the relationship between the Larson mirror parameter L of a deposit metal, and the hardness of a deteriorated layer. It is a figure which shows the relationship between the Larson mirror parameter L of the welding metal, and the stress (sigma) concerning the object site | part of the welding metal of a welding part. It is a figure which shows the temperature estimation flow which estimates the temperature of the welding part at the time of operation | movement of a heat exchanger. It is a figure which shows the relationship between the thickness d of a deteriorated layer, and the Larson mirror parameter L of the deposit metal. It is a figure which shows the thermal expansion coefficient of stainless steel, the thermal expansion coefficient of chromium molybdenum steel, and the expansion coefficient of an Inconel-type welding material. It is a figure which shows a mode that peeling has arisen in the boundary part of the heat affected zone of the preform | base_material of the heat exchanger tube formed with chromium molybdenum steel, and the Inconel-type weld metal. It is an enlarged view of the AA cross section in FIG.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.
For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained.
For example, an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state.
For example, expressions representing shapes such as quadrangular shapes and cylindrical shapes represent not only geometrically strict shapes such as quadrangular shapes and cylindrical shapes, but also irregularities and chamfers as long as the same effects can be obtained. A shape including a part or the like is also expressed.
On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of the other constituent elements.

  FIG. 1 is a perspective view schematically showing a welded portion 8 between the first heat transfer tube 4 and the second heat transfer tube 6 provided in the heat exchanger 2.

  In FIG. 1, a heat exchanger 2 is a heat exchanger used in, for example, a thermal power plant or a marine boiler, and may be used for heat exchange between combustion gas and steam, for example. In FIG. 1, the 1st heat exchanger tube 4 is used in a comparatively low temperature area | region, and is formed with the chromium molybdenum steel (1st heat resistant steel) as a ferritic heat resistant steel. The second heat transfer tube 6 is used in a relatively high temperature region, and is formed of austenitic stainless steel (second heat resistant steel). The first heat transfer tube 4 and the second heat transfer tube 6 are welded via an Inconel weld metal 10 as a Ni-based alloy. As shown in FIG. 9, the thermal expansion coefficient of the inconel weld metal 10 (the filler metal) is between the thermal expansion coefficient of chromium-molybdenum steel (Cr-Mo) and the thermal expansion coefficient of stainless steel (SUS). Has thermal expansion coefficient

  FIG. 2 shows a creep rupture test for the welded portion 8 between the first heat transfer tube 4 and the second heat transfer tube 6 shown in FIG. 1 at a test temperature of 600 ° C. under a condition that the rupture time is about 1700 hours. It is a figure which shows the cross section (cross section along the axis | shaft of the 1st heat exchanger tube 4 and the 2nd heat exchanger tube 6) and hardness distribution of the welding part 8 at the time. FIG. 3 shows a creep rupture test for the welded portion 8 between the first heat transfer tube 4 and the second heat transfer tube 6 shown in FIG. 1 at a test temperature of 600 ° C. under a condition that the rupture time is about 40000 hours. It is a figure which shows the cross section (cross section along the axis | shaft of the 1st heat exchanger tube 4 and the 2nd heat exchanger tube 6) and hardness distribution of the welding part 8 at the time. 2 and 3, the size of the square plot indicates the hardness of the metal at the plot position, and the smaller the plot size, the greater the hardness (hard) of the metal.

  As a result of intensive studies by the inventor of the present application, as shown in FIG. 2 and FIG. 3, a portion of the weld metal 10 adjacent to the heat affected zone 14 of the base material 12 of the first heat transfer tube 4 is deteriorated over time. Along with this, it was revealed that the altered layer 10a was formed. As shown in FIGS. 2 and 3, the altered layer 10a is harder than other regions, and has a different tissue state (for example, color) as viewed with a microscope or the like as compared with other regions. . 2 and FIG. 3, as the fracture time becomes longer, the deteriorated layer becomes harder and the thickness d of the deteriorated layer 10a (the width of the deteriorated layer 10a in the axial direction of the first heat transfer tube 4) increases. It became clear.

  FIG. 4 is a diagram showing a temperature estimation flow 100 for estimating the temperature T of the welded portion 8 during operation of the heat exchanger 2 using the above new knowledge.

  In one embodiment, as shown in FIG. 4, the temperature estimation flow 100 is a hardness of the deteriorated layer 10 a generated in a portion of the weld metal 10 adjacent to the heat affected zone 14 of the base material 12 of the first heat transfer tube 4. A measurement step S11 for measuring h and an estimation step S12 for estimating the temperature T during operation of the welded part 8 based on the hardness h of the deteriorated layer 10a measured in the measurement step S11 are included.

  In the measurement step S11, for example, pretreatment such as polishing and etching is performed on the surface of the welded portion 8, and the hardness h of the altered layer 10a in the appeared tissue is measured using a measuring instrument such as an ultrasonic hardness meter. You may measure. Further, as shown in FIGS. 2 and 3, the hardness h of the altered layer 10a is measured at a plurality of locations in the direction crossing the altered layer 10a, and the highest hardness among the hardnesses at the plurality of locations of the altered layer 10a is estimated. You may use for the temperature estimation in step S12.

Estimation step S12, a L ₁ derivation step S12a to derive the current value L ₁ of Larson-Miller parameters of the weld metal 10 corresponding to the hardness of the affected layer 10a measured by the measuring step S11, the temperature during operation of the weld 8 Temperature estimation step S12b for estimating T.

In L ₁ deriving step S12a, measured (preferably, the highest hardness of the hardness of the plurality of positions as described above) hardness h of the affected layer 10a measured in step S11 and the hardness h and deposited metal deteriorated layer 10a And the Larson mirror parameter of the deposited metal 10 corresponding to the hardness h of the deteriorated layer 10a measured in the measurement step S11 based on the information indicating the relationship with the Larson mirror parameter L of 10 (straight line A1 shown in FIG. 5). to derive the current value _{L 1.} Here, the straight line A1 shown in FIG. 5 may be obtained by conducting a creep rupture test in advance. For example, a creep rupture test is performed under a plurality of stress conditions (a plurality of conditions in which the stress generated in the weld metal 10 is different from each other), and the relationship between the hardness h of the altered layer 10a and the Larson mirror parameter L under each stress condition is shown. Plotting (black triangular plot in FIG. 5) may be performed, and a regression line for each plot may be obtained as a straight line A1.

In the temperature estimation step S12b, based on the current value L ₁ of Larson-Miller parameter derived by L ₁ derivation step S12a, it estimates the temperature T during operation of the weld 8. For example, the course of the current value L ₁ of Larson-Miller parameter derived by L ₁ derivation step S12a, the initial value L ₀ of the Larson-Miller parameter when unused weld metal 10, from when unused weld metal 10 Based on the time t ₁ , the temperature T during operation of the welded portion 8 can be estimated using the following (Formula 1) and (Formula 2).

Here, t ₀ is the total life t ₀ from when the weld metal 10 is not used until it breaks. The initial value L ₀ of the Larson mirror parameter when the weld metal 10 is not used is the target of the weld metal 10 of the weld 8 from the known curve U showing the relationship between the Larson mirror parameter L and the stress σ in FIG. a value corresponding to such a stress sigma _{1 (Larson} same stress conditions the stress conditions of the mirror parameter L ₁₎ to the site may be extracted as the initial value L _0. At this time, the curve U may be set based on literature values or may be determined by a creep rupture test. For the curve U, for example, a margin of about 1% is set for the average value of the Larson mirror parameters when the weld metal 10 is not used in consideration of variations, and a lower limit value of a reliability limit of about 99% is set. It may be adopted. C is a material constant determined by the material of the weld metal 10.

In the temperature estimation step S12b, in the above (Equation 1) and (Equation 2), the current value _{L 1} of Larson-Miller parameter derived by _{L 1} derivation step S12a, the initial value of the Larson Miller parameter when unused weld metal 10 By substituting L ₀ and the elapsed time t ₁ from when the weld metal 10 is not used to the present, the two simultaneous equations are solved to calculate (estimate) the temperature T during operation of the weld 8. . Thereby, the welding part 8 of the 1st heat exchanger tube 4 with which the heat exchanger 2 is equipped, and the 2nd heat exchanger tube 6 (especially part of the boundary B vicinity with the heat affected zone 14 of the base material 12 of the 1st heat exchanger tube 4). Can be accurately estimated based on the hardness h of the deteriorated layer 10a measured in the measurement step S11.

  Further, the temperature estimation flow 100 shown in FIG. 4 further includes a total life evaluation step S13 and a remaining life evaluation step S14.

In all life evaluation step S13, the in (Equation 1) and (Equation 2), the current value L ₁ of Larson-Miller parameter derived by L ₁ derivation step S12a, the initial Larson Miller parameter when unused weld metal 10 By substituting the value L ₀ and the elapsed time t ₁ from when the weld metal 10 is not used to the present time to solve these two simultaneous equations, the total life t from the time when the weld metal 10 is not used until it breaks is obtained. ₀ is calculated (evaluated).

In the residual life evaluation step S14, based on the elapsed time _{t 1} and the total lifetime _{t 0} were evaluated in all life evaluation step S13, the remaining life _t 2 to break the current weld metal 10 ₍₌ t 0 _-t 1) Is calculated (evaluated). As a result, the weld metal 10 in the welded portion of the first heat transfer tube and the second heat transfer tube provided in the heat exchanger (particularly, the portion near the boundary B with the heat affected zone 14 of the base material 12 of the first heat transfer tube 4). Can be accurately estimated based on the hardness h of the deteriorated layer measured in the measurement step S11. Thereby, it becomes easy to plan maintenance management of the heat exchanger 2, and a trouble can be prevented beforehand.

  FIG. 7 is a diagram illustrating a temperature estimation flow 200 for estimating the temperature T of the welded portion 8 during operation of the heat exchanger 2 according to an embodiment.

  The temperature estimation flow 100 shown in FIG. 4 estimates the temperature T during operation of the welded portion 8 based on the hardness h of the deteriorated layer 10a, but the temperature estimation flow 200 shown in FIG. 7 shows the hardness of the deteriorated layer 10a. The temperature T during operation of the welded portion 8 is estimated based on the thickness d of the deteriorated layer 10a instead of h. Of the temperature estimation flow 200 shown in FIG. 7, S22b, S23, and S24 are the same as S12b, S13, and S14 described with reference to FIG. The difference will be mainly described.

  In one embodiment, as shown in FIG. 7, the temperature estimation flow 200 is the thickness of the deteriorated layer 10 a generated in a portion of the weld metal 10 adjacent to the heat affected zone 14 of the base material 12 of the first heat transfer tube 4. The measurement step S21 for measuring d and the estimation step S22 for estimating the temperature T during operation of the welded portion 8 based on the thickness d of the deteriorated layer 10a measured in the measurement step S21 are included.

  In the measurement step S21, for example, pretreatment such as polishing and etching may be performed on the surface of the welded portion 8, and the thickness d of the deteriorated layer 10a in the appearing structure may be measured.

Estimation step S22, a _{L 1} derivation step S22a to derive the current value _{L 1} of Larson-Miller parameters of the weld metal 10 at the time of measurement of the measuring step S21, the temperature estimating step S22b of estimating the temperature T during operation of the weld 8 And including.

In L ₁ derivation step S22a, the thickness d of the affected layer 10a measured in the measuring step S21, the straight line shown in the information (FIG. 8 showing the relationship between the Larson-Miller parameter L of the thickness d and the deposited metal 10 deteriorated layer 10a and A2), on the basis, derives the current value L ₁ of Larson-Miller parameters of the weld metal 10 corresponding to the thickness d of the affected layer 10a measured by the measuring step S21. Here, the straight line A2 shown in FIG. 8 may be obtained in advance by performing a creep rupture test. For example, a creep rupture test is performed under a plurality of stress conditions (a plurality of conditions with different stresses generated in the weld metal 10), and the relationship between the thickness of the altered layer 10a and the Larson mirror parameter L under each stress condition is plotted ( And a regression line for each plot may be obtained as a straight line A2.

Thus, the current value on the basis of L _1, the temperature estimating step S12b, the entire service life estimation step S13 and remaining service life estimation step described with reference to FIG. 4 of the Larson-Miller parameter obtained based on the thickness d of the affected layer 10a By the same method as S14, the temperature T of the welded portion 8 during operation of the heat exchanger 2, the total life t ₀ from when the weld metal 10 is not used to fracture, and the remaining life from the present to the fracture of the weld metal 10 the t ₂ can be obtained accurately.

The present invention is not limited to the above-described embodiments, and includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms. For example, in the embodiment described above, based on the hardness h or thickness d of the affected layer 10a, but to derive the current value L ₁ of Larson-Miller parameters of the weld metal 10, the thickness and hardness h of the affected layer 10a of based on both d, it may derive the current value L ₁ of Larson-Miller parameters of the weld metal 10.

2 Heat exchanger 4 First heat transfer tube 6 Second heat transfer tube 8 Welded portion 10 Weld metal 10a Altered layer 12 Base material 14 Heat affected zone

Claims (7)

A temperature estimation method for a welded portion for estimating a temperature during operation in a welded portion between the first heat transfer tube and the second heat transfer tube included in the heat exchanger,
The first heat transfer tube is formed of a first heat resistant steel,
The second heat transfer tube is formed of a second heat resistant steel different from the first heat resistant steel,
The first heat transfer tube and the second heat transfer tube are welded via a weld metal,
A measurement step of measuring the hardness or thickness of the altered layer generated in a portion adjacent to the heat affected zone of the base material of the first heat transfer tube among the weld metal,
Based on the hardness or thickness of the deteriorated layer measured in the measurement step, an estimation step for estimating a temperature during operation of the welded portion;
Only including,
The estimation step includes
Measured in the measurement step based on the hardness or thickness of the deteriorated layer measured in the measurement step and information indicating the relationship between the hardness or thickness of the deteriorated layer and the Larson mirror parameter L of the deposited metal. and L ₁ derivation step of deriving the current value L ₁ of Larson-Miller parameters of the weld metal corresponding to the hardness or thickness of the affected layer, and
A temperature estimation step based on said current value L ₁ of the Larson-Miller parameter derived by L ₁ derivation step, to estimate the temperature during operation of the weld,
Including
In the temperature estimation step, the current value L ₁ of the Larson mirror parameter derived in the L ₁ deriving step, the initial value L ₀ of the Larson mirror parameter when the weld metal is not used, and the time when the weld metal is not used based elapsed time t ₁ to the current, from the temperature estimation method of <br/> welding unit that estimates a temperature during operation of the weld. The current value L ₁ of the Larson mirror parameter derived in the L ₁ deriving step, the initial value L ₀ of the Larson mirror parameter when the weld metal is not used, and the elapsed time from when the weld metal is not used to the present time a total life evaluation step for evaluating a total life t ₀ from when the weld metal is not used to fracture under a temperature condition during operation of the weld, based on t ₁ ;
On the basis of the said evaluated in all life evaluation step the entire service life t ₀ and the elapsed time t _1, the remaining life _{t 2 (= t 0 -t 1} ) residual life evaluating the to break the current of the weld metal An evaluation step;
The method for estimating a temperature of a weld according to claim 1 , further comprising: The method for estimating a temperature of a weld according to claim 1 , wherein the weld metal is a Ni-based alloy. The method for estimating a temperature of a weld according to claim 3 , wherein the weld metal is Inconel (registered trademark). The said 1st heat exchanger tube is a temperature estimation method of the welding part of any one of Claim 1 thru | or 4 currently formed with the ferritic heat-resistant steel. The said 1st heat exchanger tube is a temperature estimation method of the welding part of Claim 5 currently formed with chromium molybdenum steel. The said 2nd heat exchanger tube is a temperature estimation method of the welding part in any one of the Claims 1 thru | or 6 formed with austenitic stainless steel.

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