CN103870679A - Judgment method for minimum inserting section size in Charpy impact test sample recombination technology - Google Patents

Abstract

The invention relates to a judgment method for a minimum inserting section size in a Charpy impact test sample recombination technology. The judgment method comprises the following steps: preparing a recombinant test sample, testing Vickers hardness, monitoring a thermoelectric couple, carrying out metallographic observation and determining a lower limiting value Wa,min, and checking T41J, T56J and FATT (Fracture Appearance Transition Temperature) performance characteristic parameters and the like. After the lower limiting value Wa,min is determined, independent test samples are established for the T41J, T56J and FATT performance characteristic parameters of an original test sample and the recombinant test sample to carry out variance homogeneity judgment, so as to judge whether the performances are changed or not before and after the test sample is recombined; the judgment of the Wa,min is more reasonable, more accurate and more scientific.

Description

The determination methods of minimum inserting paragraph size in a kind of Charpy bar recombinant technique

Technical field

The invention belongs to Charpy bar recombinant technique field, be specifically related to the determination methods of minimum inserting paragraph size in a kind of Charpy bar recombinant technique.

Background technology

The irradiation of nuclear power plant reactor pressure vessel (RPV) is mainly by regular taking-up irradiation monitoring pipe at present, the Mechanics Performance Testing sample wherein placed, temperature testing device and dosage proving installation are carried out to test and evaluation, to determine radiation embrittlement situation and the running environment of RPV material.In order to make full use of the limited sample in irradiation monitoring pipe, sample recombinant technique is developed for disrumpent feelings sample is reassembled into new sample by welding, thereby obtains more data to improve the precision of test findings.

Existing sample recombinant technique implementation method adopts the disclosed method of Chinese invention patent that application number is 89100546.3, as shown in Figure 1, this patent is by the cramp bar 2 ' of burn-oning respectively of the Charpy bar 1 ' two ends to disrumpent feelings, the method of a new standard sample of composition increases sample quantities, thereby improves test figure reliability.Prior art realizes the regrouping process of sample conventionally with arc stud welding, electron beam welding or other welding manners.Because disrumpent feelings specimen size is limited, be the more sample of recombinating as far as possible, be necessary to determine the minimum inserting paragraph size that does not affect material property.At present, definite method of minimum inserting paragraph Size Evaluation mainly adopts following formula (1):

W _a,min>W _loss+2(W _p+max{W _HAZ,W _ANL}) （1）

Wherein, W _{a, min}minimum inserting paragraph dimension width, W _lossrefer to the width losing due to welding, W _pthe Width of Plastic Zone that impulse test process produces, W _hAZheat-affected zone width, W _aNLbe that heat is replied sector width, see Fig. 1.But this method can not judge the sample performance before and after restructuring, whether variation has occurred, if there is significant difference before the sample after restructuring and restructuring, the minimum inserting paragraph size of utilizing the method to obtain is just nonsensical, can not be used for irradiation.

Summary of the invention

The present invention seeks to provide in order to overcome the deficiencies in the prior art in a kind of Charpy bar recombinant technique not to make restructuring front and back sample performance produce the determination methods of the minimum inserting paragraph size of otherness.

For achieving the above object, the technical solution used in the present invention is: the determination methods of minimum inserting paragraph size in a kind of Charpy bar recombinant technique, and it comprises the following steps:

(a) select n the temperature spot in covering upper mounting plate and lower platform interval to carry out Charpy-type test to original sample according to the material category of Charpy bar and obtain disrumpent feelings sample, and drafting absorbs merit-temperature regression curve, shear area number percent-temperature regression curve respectively, the lower platform energy value, upper mounting plate energy value, absorption merit-temperature regression curve transition temperature, the first fitting parameter that obtain Charpy bar according to absorption merit-temperature regression curve, obtain the second fitting parameter according to shear area number percent-temperature regression curve;

(b) measure the Charpy bar Vickers hardness number in absorbing merit-temperature regression curve upper mounting plate region, and locate with the end of this sample, take the centre of this sample as the distance at initial point, decentering position as horizontal ordinate, hardness draws hardness-distance Curve as ordinate, in definition hardness-distance Curve, sample hardness mean value 10% incremental range is border, plastic zone, is W _p;

(c) cut two sections of above test sections of 5mm from described disrumpent feelings sample end and weld, when welding, arrange thermopair control point in welding region interval same distance, the temperature variation in Real-Time Monitoring welding process obtains W _aNL;

(d) welding block is carried out to metallographic observation and hardness test, take metallographic observation to heat-affected zone width and the heat-affected zone width of hardness test in large person as W _hAZ, determine W according to the difference of welding manner _loss, and determine W by following formula (1) _a, _minlower limit:

W _a,min≥W _loss+2(W _p+max{W _HAZ,W _ANL}) （1）；

(e) on disrumpent feelings sample, cut and be not less than W _{a, min}inserting paragraph, in the welding of inserting paragraph two ends, two cramp bar spreadings are to standard length, and the heart position machining gap sample of must recombinating therein, to the operation of restructuring sample repeating step (a) obtain recombinating lower platform energy value, upper mounting plate energy value, transition temperature, the first fitting parameter and second fitting parameter of sample;

(f) according to the lower platform energy value described in step (a) and step (e), upper mounting plate energy value, absorption merit-temperature regression curve transition temperature, the first fitting parameter and the second fitting parameter, utilize following formula (2), formula (3) to determine respectively the performance characteristic parameter of described Charpy bar and restructuring sample: test temperature T when impact absorbing energy is 41 joules _41J, the test temperature T of impact absorbing energy while being 56 joules _56J, fracture fibre ratio C be 50% transition temperature FATT and upper mounting plate energy USE, wherein upper mounting plate energy USE numerically equates with A2,

$E=\frac{A1-A2}{1+\exp \left(\frac{T-\mathrm{Tt}}{\mathrm{\θ}1}\right)}+A2---\left(2\right)$ With $C=100-\frac{100}{1+\exp \left(\frac{T-\mathrm{FATT}}{\mathrm{\θ}2}\right)}---\left(3\right),$

In formula: E is impact absorbing energy, A1 is lower platform energy value, A2 is upper mounting plate energy value, T is test temperature, Tt is for absorbing merit-temperature regression curve transition temperature, and C is fracture fibre ratio, and FATT is that fracture fibre ratio is 50% transition temperature, θ 1 is the first fitting parameter, and θ 2 is the second fitting parameter;

(g) by the performance characteristic parameter T of the Charpy bar described in step (f) and restructuring sample _41J, T _56J, FATT, USE set up respectively the independent sample of two normal distributions: independent sample is carried out to F check, for given level of significance α=0.05 and degree of freedom n-1, when F value is less than critical value F _{0.05/2 (n, n)}, the homogeneity of variance of two samples, adopts t check; When F value is greater than critical value F _{0.05/2 (n, n)}, the Heteroscedasticity of two samples, adopts t ' check; When t or the t ' of independent sample are worth all lower than critical value t _{α (ν)}time, W _{a, min}meet minimum inserting paragraph size.

Optimally, in step (b), described welding manner is electron beam welding.

Optimally, in step (c), described thermopair control point distance is 0.5mm.

Because technique scheme is used, the present invention compared with prior art has following advantages: the determination methods of minimum inserting paragraph size in Charpy bar recombinant technique of the present invention, and by definite W _{a, min}after lower limit, continue the performance characteristic parameter T to original sample, restructuring sample _41J, T _56J, FATT, USE set up independent sample and carry out homogeneity of variance judgement, and then judges that whether the performance before and after sample restructuring changes, and makes W _{a, min}judgement more rationally, more accurately, science more.

Accompanying drawing explanation

Accompanying drawing 1 is for the summer is than the sample schematic diagram of recombinating;

Accompanying drawing 2 is restructuring sample hardness-longitudinal center line distance Curve figure;

Accompanying drawing 3 is restructuring sample metallographic test pattern;

Accompanying drawing 4 is restructuring sample hardness distribution.

Embodiment

Below in conjunction with accompanying drawing, the preferred embodiment of the invention is elaborated:

The determination methods of minimum inserting paragraph size in Charpy bar recombinant technique of the present invention, it comprises the following steps:

(a) select n the temperature spot in covering upper mounting plate and lower platform interval respectively original sample to be carried out to Charpy-type test according to the material category of Charpy bar and obtain disrumpent feelings sample, and drafting absorbs merit-temperature regression curve, shear area number percent-temperature regression curve respectively, the lower platform energy value, upper mounting plate energy value, absorption merit-temperature regression curve transition temperature, the first fitting parameter that obtain Charpy bar according to absorption merit-temperature regression curve, obtain the second fitting parameter according to shear area number percent-temperature regression curve; In the present embodiment, because the material of Charpy bar is RPV material, the temperature spot number n=8 that it is chosen, probe temperature is respectively 60 ℃, 25 ℃, 0 ℃ ,-20 ℃ ,-30 ℃ ,-40 ℃ ,-60 ℃ and-80 ℃;

(b) measure the Charpy bar Vickers hardness number in absorbing merit-temperature regression curve upper mounting plate region, and locate with the end of this sample, take the centre of this sample as the distance at initial point, decentering position as horizontal ordinate, hardness draws hardness-distance Curve as ordinate, in definition hardness-distance Curve, sample hardness mean value 10% incremental range is border, plastic zone, is W _p; In the present embodiment, because initial point near zone gross distortion all occurs after thrusting, sample hardness strong point is from 4mm, and as shown in Figure 2, to exceed hardness mean value 10% incremental range as border, plastic zone, in Fig. 2, Width of Plastic Zone is 8mm, and sample W recombinates _pfor 8mm;

(c) cut two sections of above test sections of 5mm from described disrumpent feelings sample end and weld, when welding, arrange thermopair control point in welding region interval same distance, the temperature variation in Real-Time Monitoring welding process obtains W _aNL;

(d) welding block is carried out to metallographic observation and hardness test, take metallographic observation to heat-affected zone width and the heat-affected zone width of hardness test in large person as W _hAZ, in the present embodiment, metallographic observation results as shown in Figure 3, heat-affected zone width largest portion is 2.9mm, hardness distribution as shown in Figure 4, and middle peak region is heat-affected zone width (welding harden zone), width is 3.5mm, and the large person 3.5mm getting in both is W _hAZ; Because welding manner in the present embodiment is electron beam welding, for electron beam welding, W _loss=0 and this test in W _aNLbe about 3mm, and determine W by following formula (1) _{a, min}lower limit:

W _a,min≥W _loss+2(W _p+max{W _HAZ,W _ANL}) （1）

Can calculate W according to above-mentioned data _{a, min}for 20mm, therefore the sample of desirable 20mm and above size carries out next step test as inserting paragraph size, and in the present embodiment, take certain reactor pressure vessel material, the Charpy bar of irradiation and minimum inserting paragraph are not tested as the restructuring sample of 23mm as sample;

(e) on disrumpent feelings sample, cut and be not less than W _{a, min}inserting paragraph, in the welding of inserting paragraph two ends, two cramp bar spreadings are to standard length, and the heart position machining gap sample (as shown in Figure 1) of must recombinating therein, to the operation of restructuring sample repeating step (a) obtain recombinating lower platform energy value, upper mounting plate energy value, transition temperature, the first fitting parameter and second fitting parameter of sample;

(f) according to the lower platform energy value described in step (a) and step (e), upper mounting plate energy value, absorption merit-temperature regression curve transition temperature, the first fitting parameter and the second fitting parameter, utilize following formula (2), formula (3) to determine respectively the performance characteristic parameter of described Charpy bar and restructuring sample: test temperature T when impact absorbing energy is 41 joules _41J, the test temperature T of impact absorbing energy while being 56 joules _56J, fracture fibre ratio C be 50% transition temperature FATT and upper mounting plate energy USE, wherein upper mounting plate energy USE numerically equates with A2,

$E=\frac{A1-A2}{1+\exp \left(\frac{T-\mathrm{Tt}}{\mathrm{\θ}1}\right)}+A2---\left(2\right)$ With $C=100-\frac{100}{1+\exp \left(\frac{T-\mathrm{FATT}}{\mathrm{\θ}2}\right)}---\left(3\right),$

In formula: E is impact absorbing energy, A1 is lower platform energy value, A2 is upper mounting plate energy value, T is test temperature, Tt is for absorbing merit-temperature regression curve transition temperature, and C is fracture fibre ratio, and FATT is that fracture fibre ratio is 50% transition temperature, θ 1 is the first fitting parameter, and θ 2 is the second fitting parameter;

(g) can test multiple Charpy bars and restructuring sample, for the performance characteristic parameter T that step (f) is obtained _41J, T _56J, FATT, USE set up the independent sample of two normal distributions, in the present embodiment, the minimum inserting paragraph of restructuring sample is of a size of 23mm, performance characteristic parameter and the standard deviation of itself and Charpy bar are listed in table 1;

Performance characteristic parameter and the standard deviation of table 1 Charpy bar and restructuring sample

Then independent sample is carried out to F check, check checking homogeneity of variance:

1) F of independent sample check

For the independent sample of two normal distributions, sample variance represents according to following formula respectively:

${\mathrm{<figure-callout\; id="1"\; label="S"\; filenames="HDA0000468573270000011.png"\; state="\{\{state\}\}">S</figure-callout>}}_1^2=\frac{1}{n_1-1}\underset{i=1}{\overset{n_1}{\mathrm{\&Sigma;}}}{(x_1-\stackrel{\&OverBar;}{x})}^2---\left(4\right)$

${\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="HDA0000468573270000011.png,HDA0000468573270000021.png"\; state="\{\{state\}\}">S</figure-callout>}}_2^2=\frac{1}{n_2-1}\underset{i=1}{\overset{n_2}{\mathrm{\&Sigma;}}}{(y_1-\stackrel{\&OverBar;}{y})}^2---\left(5\right)$

According to the magnitude relationship between these two sample variances, set up statistic F:

$F=\frac{S_{\mathrm{Bigger}}^2}{S_{\mathrm{smaller}}^2}---\left(6\right)$

The degree of freedom of two samples is respectively n ₁-1 and n ₂-1, wherein n ₁=20, n ₂=18, given level of significance α=0.05, if the F value of calculating is less than critical F _{0.05/2 (n1, n2)}, the homogeneity of variance of two samples, adopts t check; If the F value of calculating is higher than critical F _{0.05/2 (n1, n2)}, the Heteroscedasticity of two samples, adopts t ' check;

2) t of two independent samples check

For two normal distribution samples independently, set up statistic t:

$t=\frac{\stackrel{\&OverBar;}{{\mathrm{<figure-callout\; id="1"\; label="X"\; filenames="HDA0000468573270000011.png"\; state="\{\{state\}\}">X</figure-callout>}}_1}-\stackrel{\&OverBar;}{{\mathrm{<figure-callout\; id="2"\; label="X"\; filenames="HDA0000468573270000011.png,HDA0000468573270000021.png"\; state="\{\{state\}\}">X</figure-callout>}}_2}}{{\mathrm{<figure-callout\; id="1"\; label="S\; X"\; filenames="HDA0000468573270000011.png"\; state="\{\{state\}\}">S</figure-callout>}}_{\stackrel{}{X_{}}}}---\left(7\right)$

with be respectively sample average, the degree of freedom ν that t distributes is n ₁+ n ₂-2, wherein n ₁=20, n ₂=18, S1 and S2 are respectively the standard deviation of two samples

${\mathrm{<figure-callout\; id="1"\; label="S\; X"\; filenames="HDA0000468573270000011.png"\; state="\{\{state\}\}">S</figure-callout>}}_{\stackrel{}{X_{}}}=\sqrt{S_C^2(\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="HDA0000468573270000011.png"\; state="\{\{state\}\}">n</figure-callout>}}_1}+\frac{1}{n_2})}---\left(8\right)$

$S_C^2=\frac{(n_1-1)S_C^2+(n_2-1)S_2^2}{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="HDA0000468573270000011.png"\; state="\{\{state\}\}">n</figure-callout>}}_1+n_2-2}---\left(9\right)$

3) t ' of two independent samples check

For two independent samples of Heteroscedasticity, set up statistic t ':

$t^{\&prime;}=\frac{\stackrel{\&OverBar;}{X_1}-\stackrel{\&OverBar;}{{\mathrm{<figure-callout\; id="2"\; label="X"\; filenames="HDA0000468573270000011.png,HDA0000468573270000021.png"\; state="\{\{state\}\}">X</figure-callout>}}_2}}{\sqrt{\frac{{\mathrm{<figure-callout\; id="1"\; label="S"\; filenames="HDA0000468573270000011.png"\; state="\{\{state\}\}">S</figure-callout>}}_1^2}{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="HDA0000468573270000011.png"\; state="\{\{state\}\}">n</figure-callout>}}_1}+\frac{{\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="HDA0000468573270000011.png,HDA0000468573270000021.png"\; state="\{\{state\}\}">S</figure-callout>}}_2^2}{n_2}}}---\left(10\right)$

The degree of freedom ν that this t ' distributes calculates by following formula:

$v=\frac{({\mathrm{<figure-callout\; id="1"\; label="S\; X"\; filenames="HDA0000468573270000011.png"\; state="\{\{state\}\}">S</figure-callout>}}_{\stackrel{}{X_{}}}^{\stackrel{\&OverBar;}{{}_1}}+{\mathrm{<figure-callout\; id="2"\; label="S\; X"\; filenames="HDA0000468573270000011.png,HDA0000468573270000021.png"\; state="\{\{state\}\}">S</figure-callout>}}_{\stackrel{}{X_{}}}^{\stackrel{\&OverBar;}{{}_2}})}{\frac{{\mathrm{<figure-callout\; id="1"\; label="S\; X"\; filenames="HDA0000468573270000011.png"\; state="\{\{state\}\}">S</figure-callout>}}_{\stackrel{}{X_{}}}^{\stackrel{\&OverBar;}{{}_1}}}{n_1-1}+\frac{S_{\stackrel{\&OverBar;}{X_2}}^4}{n_2-1}}---\left(11\right)$

For given level of significance α=0.05, if the t/t ' of statistic is worth lower than critical t α (ν), illustrate that two sample characteristics not there are differences, W _{a, min}meet minimum inserting paragraph size; If the t/t ' of statistic is worth higher than critical t _{α (ν)}, illustrate that two sample characteristics there are differences, W _{a, min}do not meet minimum inserting paragraph size.

In the present embodiment, the performance characteristic parameter difference opposite sex check data of Charpy bar and restructuring sample is listed in table 2.As can be drawn from Table 2, the performance parameter T of 23mm inserting paragraph restructuring sample _41J, T _56J, all property of there are differences not of FATT, USE, 23mm is minimum inserting paragraph size.

Table 2 characteristic parameter test of difference

Above-described embodiment is only explanation technical conceive of the present invention and feature; its object is to allow person skilled in the art can understand content of the present invention and implement according to this; can not limit the scope of the invention with this; all equivalences that Spirit Essence is done according to the present invention change or modify, within all should being encompassed in protection scope of the present invention.

Claims (3)

1. a determination methods for minimum inserting paragraph size in Charpy bar recombinant technique, is characterized in that: it comprises the following steps:

(a) select n the temperature spot in covering upper mounting plate and lower platform interval respectively original sample to be carried out to Charpy-type test according to the material category of Charpy bar and obtain disrumpent feelings sample, and drafting absorbs merit-temperature regression curve, shear area number percent-temperature regression curve respectively, the lower platform energy value, upper mounting plate energy value, absorption merit-temperature regression curve transition temperature, the first fitting parameter that obtain Charpy bar according to absorption merit-temperature regression curve, obtain the second fitting parameter according to shear area number percent-temperature regression curve;

(b) measure the Charpy bar Vickers hardness number in absorbing merit-temperature regression curve upper mounting plate region, and locate with the end of this sample, take the centre of this sample as the distance at initial point, decentering position as horizontal ordinate, hardness draws hardness-distance Curve as ordinate, in definition hardness-distance Curve, sample hardness mean value 10% incremental range is border, plastic zone, is Width of Plastic Zone W _p;

(c) cut two sections of above test sections of 5mm from described disrumpent feelings sample end and weld, when welding, arrange thermopair control point in welding region interval same distance, the temperature variation in Real-Time Monitoring welding process obtains heat and replys sector width W _aNL;

(d) welding block is carried out to metallographic observation and hardness test, take metallographic observation to heat-affected zone width and the heat-affected zone width of hardness test in large person as W _hAZ, determine W according to the difference of welding manner _loss, and determine W by following formula (1) _a, _minlower limit:

W _a,min≥W _loss+2(W _p+max{W _HAZ,W _ANL}) （1）；

(e) on disrumpent feelings sample, cut and be not less than W _{a, min}inserting paragraph, in the welding of inserting paragraph two ends, two cramp bar spreadings are to standard length, and the heart position machining gap sample of must recombinating therein, to the operation of restructuring sample repeating step (a) obtain recombinating lower platform energy value, upper mounting plate energy value, transition temperature, the first fitting parameter and second fitting parameter of sample;

(f) according to the lower platform energy value described in step (a) and step (e), upper mounting plate energy value, absorption merit-temperature regression curve transition temperature, the first fitting parameter and the second fitting parameter, utilize following formula (2), formula (3) to determine respectively the performance characteristic parameter of described Charpy bar and restructuring sample: test temperature T when impact absorbing energy is 41 joules _41J, the test temperature T of impact absorbing energy while being 56 joules _56J, fracture fibre ratio C be 50% transition temperature FATT and upper mounting plate energy USE, wherein upper mounting plate energy USE numerically equates with A2,

$E=\frac{A1-A2}{1+\exp \left(\frac{T-\mathrm{Tt}}{\mathrm{\&theta;}1}\right)}+A2---\left(2\right)$ With $C=100-\frac{100}{1+\exp \left(\frac{T-\mathrm{FATT}}{\mathrm{\&theta;}2}\right)}---\left(3\right),$

In formula: E is impact absorbing energy, A1 is lower platform energy value, A2 is upper mounting plate energy value, T is test temperature, Tt is for absorbing merit-temperature regression curve transition temperature, and C is fracture fibre ratio, and FATT is that fracture fibre ratio is 50% transition temperature, θ 1 is the first fitting parameter, and θ 2 is the second fitting parameter;

(g) by the performance characteristic parameter T of the Charpy bar described in step (f) and restructuring sample _41J, T _56J, FATT, USE set up respectively the independent sample of two normal distributions: independent sample is carried out to F check, for given level of significance α=0.05 and degree of freedom n-1, when F value is less than critical value F _{0.05/2 (n1, n2)}, the homogeneity of variance of two samples, adopts t check; When F value is greater than critical value F _{0.05/2 (n1, n2)}, the Heteroscedasticity of two samples, adopts t ' check; When t or the t ' of independent sample are worth all lower than critical value t _{α (ν)}time, W _{a, min}meet minimum inserting paragraph size.

2. minimum inserting paragraph method for determining dimension in Charpy bar recombinant technique according to claim 1, is characterized in that: in step (b), described welding manner is electron beam welding.

3. minimum inserting paragraph method for determining dimension in Charpy bar recombinant technique according to claim 1, is characterized in that: in step (c), described thermopair control point distance is 0.5mm.

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