CN111157567A - Method for measuring volume ratio of two-phase transformation of low-alloy high-strength steel during continuous cooling - Google Patents

Method for measuring volume ratio of two-phase transformation of low-alloy high-strength steel during continuous cooling Download PDF

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CN111157567A
CN111157567A CN202010023163.7A CN202010023163A CN111157567A CN 111157567 A CN111157567 A CN 111157567A CN 202010023163 A CN202010023163 A CN 202010023163A CN 111157567 A CN111157567 A CN 111157567A
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雷玄威
杨荣玻
肖琳琳
丁佳俊
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Buddhist Tzu Chi General Hospital
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Abstract

The invention provides a method for measuring the volume ratio of two-phase transition of continuous cooling of low-alloy high-strength steel, belonging to the technical field of physical materials. Firstly, measuring a thermal expansion curve of the low-alloy high-strength steel in a continuous cooling two-phase transformation process; carrying out lever method processing on a thermal expansion curve measured in the process of continuously cooling two phases of the low-alloy high-strength steel to obtain a phase change volume fraction curve; carrying out numerical differentiation on the phase change volume fraction curve to obtain a numerical differentiation curve of the phase change volume fraction; two overlapped waves on a numerical differential curve of the volume fraction of the phase change are separated through a plotting rule, and the area ratio of the two waves is the volume ratio of the two phase transition by measuring the areas of the two separated waves. The invention can solve the problem of calculating the volume fraction of each phase when the phase change temperature intervals are partially overlapped, and the error of the calculation result is smaller; the method can be used for calculating the volume ratio of three phases or multiple phases of the low-alloy high-strength steel.

Description

Method for measuring volume ratio of two-phase transformation of low-alloy high-strength steel during continuous cooling
Technical Field
The invention relates to the technical field of physical materials, in particular to a method for measuring the volume ratio of two-phase transition of low-alloy high-strength steel in continuous cooling.
Background
The low-alloy high-strength steel is widely applied to various engineering structures as a class of steel materials with the largest application amount, and is the most important industrial raw material for promoting economic construction and social development of China. The CCT (closed circuit diagram) of the low-alloy high-strength steel welding is used as a key basis for predicting the structure and performance of a welding line and a heat affected zone, and is the theoretical basis for steel material welding wire development, weldability research, welding line and heat affected zone performance regulation and control and welding process optimization design.
The most common method for measuring the welding CCT is a thermal expansion method which is mainly completed by a thermal simulation experiment machine, and the obtained data comprises thermal expansion amount, temperature, time and the like; wherein the calculation of the volume fraction of each phase is a key step and content in the determination of the welding CCT diagram.
Methods currently in use include metallographic methods, lever methods and extended lever methods. The limitation of the metallographic method is that the metallographic method cannot be applied when the structures and the appearances of all phases are very similar, the limitation of the lever method is that the lever method cannot be applied when phase transition temperature intervals are overlapped when all phases are transformed, the lever method is expanded, the method provided by the applicant team can partially solve the problem of phase volume fraction calculation which cannot be solved by the lever method, and the problem of phase volume fraction calculation when all phase transition temperature intervals are partially overlapped can be solved. The applicant team previously proposed a method for determining a two-phase transition volume ratio based on a numerical differentiation method (patent one) and obtained an authorized patent (reference 1: huang dawa, renxue, a method for determining a two-phase transition volume ratio based on a numerical differentiation method [ P ]. patent No. ZL201510335105.7) with the guidance of an extension lever method as a thought, which has the advantages of solving the problem of calculating the phase volume fraction that cannot be solved by the lever method, but has the disadvantages of complicated operation process and large calculation error. Then, the applicant group proposed a method of calculating the two-phase transformation volume ratio of the metal material by measuring the area (patent two) and applied for a patent (reference 2: renxuanwei, yangrongbo, huangshuangshui, xianlin, dingjiajun. a method of calculating the two-phase transformation volume ratio of the metal material by measuring the area [ P ]. application No. 201910807070.0), which is simpler and more convenient than the previous methods, and the calculation error is reduced but still larger than the previous methods.
On the basis of summarizing a large number of phase change mechanical laws of the low-alloy high-strength steel, the applicant team provides a method for measuring the volume ratio of two phases of the low-alloy high-strength steel in the continuous cooling process on the basis of calculating the larger error of the two phase change volume ratio of the metal material by the two methods, and the method is more targeted and has the synergistic beneficial effects that the operation process is simpler than that of the method in the first patent and the calculation error is smaller than that of the method in the second patent.
Disclosure of Invention
The invention aims to solve the technical problems that in the method for measuring the volume ratio of two phases of low-alloy high-strength steel in the continuous cooling process in the prior art, the operation process of the method for measuring the volume fraction of each phase is complicated and the calculation error is large when the phase-change temperature intervals are partially overlapped.
The invention provides a method for measuring the volume ratio of two phases of continuous cooling of low-alloy high-strength steel, which is used for measuring a thermal expansion curve of the low-alloy high-strength steel in the two-phase conversion process of the continuous cooling; carrying out lever method processing on a thermal expansion curve measured in the process of continuously cooling two phases of the low-alloy high-strength steel to obtain a phase change volume fraction curve; carrying out numerical differentiation on the phase change volume fraction curve to obtain a numerical differentiation curve of the phase change volume fraction; two overlapped waves on a numerical differential curve of the volume fraction of the phase change are separated through a plotting rule, and the area ratio of the two waves is the volume ratio of the two phase transition by measuring the areas of the two separated waves.
Further, the method is specifically carried out according to the following steps:
s1, obtaining test data of the thermal expansion amount corresponding to the temperature change of the low-alloy high-strength steel in the continuous cooling two-phase transformation process by using a test device;
s2, drawing a thermal expansion curve of the thermal expansion amount corresponding to the temperature change by taking the temperature as an abscissa and the thermal expansion amount as an ordinate according to the test data of S1;
s3, extending the linear change parts at the two ends of the curve of S2, carrying out lever method processing to obtain data of the total phase change volume fraction corresponding to temperature change, and drawing a phase change volume fraction curve;
s4, after the data of S3 are subjected to differential processing, a numerical differential curve of the phase change volume fraction corresponding to temperature change is made by taking the temperature as an abscissa and the differentiated data as an ordinate;
s5, according to the numerical differential curve of the phase change volume fraction obtained in the S4, the two overlapped waves on the curve are separated by adopting a drawing rule of separating the two overlapped waves on the curve, the areas of the two waves are measured, and the area ratio of the two waves is the volume ratio of the two phases which are converted in sequence.
Furthermore, the temperature interval for data acquisition in S1 is 0.01-0.1 ℃, the precision of the temperature data is 0.01-0.1 ℃, and the precision of the thermal expansion data of the material is 0.01-0.1 μm.
Further, the steps of the lever method processing in S3 are: the curve of the thermal expansion amount corresponding to the temperature change is divided into 3 parts which are respectively approximate straight line parts D before phase change1(T), Curve D in the phase transition2(T) and a substantially linear portion D after phase transition3(T)；
Fitting the thermal expansion curve before and after phase change to obtain a straight line D1(T) and D3(T); calculating the phase change volume fraction of the phase change temperature interval as
Figure BDA0002361524490000031
Wherein T isiTemperature data, T, recorded for a thermal simulation test apparatussStarting temperature, T, of the overall phase transitionf' end temperature of the overall phase transition, D2(Ti) Amount of thermal expansion, f (T), recorded for a thermal simulation test apparatusi) The data of the phase change volume fraction corresponding to the temperature change is obtained;
volume of phase changeThe data acquisition method of the numerical differential curve of the fraction corresponding to the temperature change comprises the following steps:
Figure BDA0002361524490000032
wherein f (T)i+1) Is at a temperature Ti+1Fractional value of time-phase change volume, Ti+1Is TiThe next recorded temperature.
Further, the plotting rule in S5 includes the following steps:
s51, representing the differential curve of the phase change volume fraction into two mutually overlapped waves which respectively correspond to the first phase and the second phase; the start point of the first wave and the end point of the second wave correspond to the start temperature T of the first phase transitionsAnd a finishing temperature T 'of the second phase transition'f(ii) a On this graph, a horizontal line l corresponding to the vertical mark 0 is drawn, which intersects the differential curve of the phase change volume fraction at TsAnd T'fPoint;
s52, according to the characteristics of the curve, assuming the wave trough of the second wave to be A1Point, passing A1Dotted vertical line o' and horizontal line l1，l1Has a ordinate of P1Through the ordinate
Figure BDA0002361524490000041
P1Position as horizontal line l2(ii) a Differential curve T 'of phase-variant volume fraction'fA1The segment is defined as curve m1Horizontal line l2And curve m1Cross over at point A2；
S53 differential curve A of phase change volume fraction1A2The segment is fitted by a straight line segment p ', the p ' is extended to intersect with the perpendicular line o ', an approximately symmetrical straight line p of the straight line p ' is drawn by taking the perpendicular line o ' as a symmetrical line, and the straight line p and the straight line l are2And l are crossed at the point A3And T's，A3Point sum A2The vertical distances from the point to the vertical line o 'are respectively delta T'1And Δ T'2，ΔT′1And Δ T'2Must satisfy a specific condition relationship of Delta T'1＝aΔT′2；
S54, over T'sThe point is taken as a perpendicular o, and the perpendicular o intersects with a differential curve of the phase-change volume fraction at a point A4Differential curve A of phase change volume fraction4A1Segment and TsA4The segments are respectively defined as curves m2And m3(ii) a Per A4Dotted horizontal line l3，l3Has a ordinate of P2Through the ordinate
Figure BDA0002361524490000042
Position as horizontal line l4Horizontal line l4And curve m3Cross over at point A5；
S55 passing through curve segment m2And a straight line p, curve q: curve m2The vertical coordinate values corresponding to the straight line p and the curve q satisfy the relation q + p ═ m2(ii) a Curve q and horizontal line l4And l are crossed at the point A6And Tf，A5Point sum A6The vertical distances of the points from the perpendicular o are respectively Delta T1And Δ T2Requires Δ T1And Δ T2Also satisfies a specific conditional relationship Δ T1＝aΔT2If Δ T1And Δ T2If the value of (A) fails to satisfy the specific condition relationship, the second valley point A is adjusted1Positions on a differential curve of the phase change volume fraction until all the above positional relationships are satisfied;
s56, measuring the first wave S1And a second wave S2In the figure, the area ratio of the two phases is the volume ratio of the two phases which are successively transformed.
Further, when line segment T'sT′fOr TsTfDelta T 'when the lengths in the figure are respectively 150-100 ℃, 100-50 ℃ and 50-20℃'1＝aΔT′2Or Δ T1＝aΔT2The a is 0.65 + -0.05, 0.75 + -0.05 and 0.85 + -0.05 respectively.
Further, S1From horizontal line l, curve m3And curve q enclose, S2From horizontal line l, curve m1And a straight line p.
The invention obtains the numerical differential curve of the phase change volume fraction by measuring the data of the thermal expansion of the low-alloy high-strength steel along with the temperature change in the two-phase transformation process, and directly obtains the two-phase volume ratio by measuring the area in the graph through a certain drawing rule; the method can solve the problem of calculating the volume fraction of each phase when the phase change temperature intervals are partially overlapped, and has the advantages of simple operation method and smaller calculation error.
Therefore, the invention enriches the application of the expansion lever method, is suitable for the condition when the two phases of the low-alloy high-strength steel are overlapped in partial temperature intervals, and can reduce the calculation error of the prior method. Meanwhile, the method can be used for calculating the volume ratio of three phases or multiple phases of the low-alloy high-strength steel.
Drawings
The technical solution in the embodiments of the present patent will be further explained with reference to the drawings in the embodiments of the present patent.
FIG. 1 is a schematic diagram of the volume fraction numerical differential curve of the low-alloy high-strength steel under continuous cooling condition and the plotting rule.
Detailed Description
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.
The invention aims to solve the technical problems that in the method for measuring the volume ratio of two phases of low-alloy high-strength steel in the continuous cooling process in the prior art, the operation process of the method for measuring the volume fraction of each phase is complicated and the calculation error is large when the phase-change temperature intervals are partially overlapped.
In order to solve the technical problems, the invention provides a method for measuring the volume ratio of two-phase continuous cooling transformation of low-alloy high-strength steel, which is used for measuring the thermal expansion curve of the low-alloy high-strength steel in the two-phase continuous cooling transformation process; carrying out lever method processing on a thermal expansion curve measured in the process of continuously cooling two phases of the low-alloy high-strength steel to obtain a phase change volume fraction curve; carrying out numerical differentiation on the phase change volume fraction curve to obtain a numerical differentiation curve of the phase change volume fraction; two overlapped waves on a numerical differential curve of the volume fraction of the phase change are separated through a plotting rule, and the area ratio of the two waves is the volume ratio of the two phase transition by measuring the areas of the two separated waves.
The method is specifically carried out according to the following steps:
s1, obtaining test data of the thermal expansion amount corresponding to the temperature change of the low-alloy high-strength steel in the continuous cooling two-phase transformation process by using a test device;
s2, drawing a thermal expansion curve of the thermal expansion amount corresponding to the temperature change by taking the temperature as an abscissa and the thermal expansion amount as an ordinate according to the test data of S1;
s3, extending the linear change parts at the two ends of the curve of S2, carrying out lever method processing to obtain data of the total phase change volume fraction corresponding to temperature change, and drawing a phase change volume fraction curve;
s4, after the data of S3 are subjected to differential processing, a numerical differential curve of the phase change volume fraction corresponding to temperature change is made by taking the temperature as an abscissa and the differentiated data as an ordinate;
s5, according to the numerical differential curve of the phase change volume fraction obtained in the S4, the two overlapped waves on the curve are separated by adopting a drawing rule of separating the two overlapped waves on the curve, the areas of the two waves are measured, and the area ratio of the two waves is the volume ratio of the two phases which are converted in sequence.
Particularly, the temperature interval for data acquisition in S1 is 0.01-0.1 ℃, the precision of the temperature data is 0.01-0.1 ℃, and the precision of the thermal expansion data of the material is 0.01-0.1 μm.
Specifically, the steps of the lever method processing in S3 are: the curve of the thermal expansion amount corresponding to the temperature change is divided into 3 parts which are respectively approximate straight line parts D before phase change1(T), Curve D in the phase transition2(T) and a substantially linear portion D after phase transition3(T)；
Fitting the thermal expansion curve before and after phase change to obtain a straight line D1(T) and D3(T); calculating the phase change volume fraction of the phase change temperature interval as
Figure BDA0002361524490000061
Wherein T isiTemperature data, T, recorded for a thermal simulation test apparatussStarting temperature, T, of the overall phase transitionf' end temperature of the overall phase transition, D2(Ti) Amount of thermal expansion, f (T), recorded for a thermal simulation test apparatusi) The data of the phase change volume fraction corresponding to the temperature change is obtained;
the data acquisition method of the numerical differential curve of the phase change volume fraction corresponding to the temperature change comprises the following steps:
Figure BDA0002361524490000062
wherein f (T)i+1) Is at a temperature Ti+1Fractional value of time-phase change volume, Ti+1Is TiThe next recorded temperature.
Specifically, the plotting rule in S5 includes the steps of:
s51, representing the differential curve of the phase change volume fraction into two mutually overlapped waves which respectively correspond to the first phase and the second phase; the start point of the first wave and the end point of the second wave correspond to the start temperature T of the first phase transitionsAnd a finishing temperature T 'of the second phase transition'f(ii) a On this graph, a horizontal line l corresponding to the vertical mark 0 is drawn, which intersects the differential curve of the phase change volume fraction at TsAnd T'fPoint;
s52, according to the characteristics of the curve, assuming the wave trough of the second wave to be A1Point, passing A1Dotted vertical line o' and horizontal line l1，l1Has a ordinate of P1Through the ordinate
Figure BDA0002361524490000071
P1Position as horizontal line l2(ii) a Differential curve T 'of phase-variant volume fraction'fA1The segment is defined as curve m1Horizontal line l2And curve m1Cross over at point A2；
S53 differential curve A of phase change volume fraction1A2The segments being carried out with straight segments pFitting, extending p 'to intersect with the perpendicular o', taking the perpendicular o 'as a symmetrical line, drawing an approximately symmetrical straight line p of the straight line p', and connecting the straight line p with the straight line l2And l are crossed at the point A3And T's，A3Point sum A2The vertical distances from the point to the vertical line o 'are respectively delta T'1And Δ T'2，ΔT′1And Δ T'2Must satisfy a specific condition relationship of Delta T'1＝aΔT′2；
S54, over T'sThe point is taken as a perpendicular o, and the perpendicular o intersects with a differential curve of the phase-change volume fraction at a point A4Differential curve A of phase change volume fraction4A1Segment and TsA4The segments are respectively defined as curves m2And m3(ii) a Per A4Dotted horizontal line l3，l3Has a ordinate of P2Through the ordinate
Figure BDA0002361524490000072
P2Position as horizontal line l4Horizontal line l4And curve m3Cross over at point A5；
S55 passing through curve segment m2And a straight line p, curve q: curve m2The vertical coordinate values corresponding to the straight line p and the curve q satisfy the relation q + p ═ m2(ii) a Curve q and horizontal line l4And l are crossed at the point A6And Tf，A5Point sum A6The vertical distances of the points from the perpendicular o are respectively Delta T1And Δ T2Requires Δ T1And Δ T2Also satisfies a specific conditional relationship Δ T1＝aΔT2If Δ T1And Δ T2If the value of (A) cannot satisfy the specific condition relation, adjusting the position of a second valley point A on a differential curve of the phase change volume fraction until all the position relations are satisfied;
s56, measuring the first wave S1And a second wave S2In the figure, the area ratio of the two phases is the volume ratio of the two phases which are successively transformed.
Particularly, when line segment T'sT′fOr TsTfDelta T 'when the lengths in the figure are respectively 150-100 ℃, 100-50 ℃ and 50-20℃'1＝aΔT′2Or Δ T1＝aΔT2The a is 0.65 + -0.05, 0.75 + -0.05 and 0.85 + -0.05 respectively.
In particular, S1From horizontal line l, curve m3And curve q enclose, S2From horizontal line l, curve m1And a straight line p.
The first embodiment is as follows:
measuring a series of data of thermal expansion quantity of certain low-alloy high-strength steel along with temperature change under the condition that the cooling rate is 0.8 ℃/s through Gleeble, wherein the thermal expansion quantity precision reaches 10-5mm, temperature accuracy up to 10-2The temperature is controlled, and the data acquisition frequency is 1 Hz. The numerical differential curve of the phase change volume fraction (corresponding to the temperature change) obtained by correspondingly sorting the data is shown in fig. 1. The curve in fig. 1 represents the superposition of two waves, the first and the second wave corresponding respectively to two phases of successive transitions.
The first step is as follows: a horizontal line l corresponding to the vertical mark 0 is drawn on the graph, and the starting point T of the first wave is marked on the horizontal line lsAnd end point T 'of the second wave'fCorresponding to the temperature at which the first phase change starts and the temperature at which the second phase change ends, respectively;
the second step is that: assuming the trough of the second wave is A1Point, passing A1Dotted vertical line o' and horizontal line l1，l1Has a ordinate of P1Through the ordinate
Figure BDA0002361524490000081
P1Position as horizontal line l2(ii) a Differential curve T 'of phase-variant volume fraction'fA1The segment is defined as curve m1Horizontal line l2And curve m1Cross over at point A2；
The third step: differential curve A of phase change volume fraction1A2The segments are fitted by straight segments p ', p' is extended to intersect with the perpendicular o ', and the perpendicular o' is taken as a symmetry line to form a straight line pApproximately symmetrical line p, line p and line l2And l are crossed at the point A3And T's，A3Point sum A2The vertical distances from the point to the vertical line o 'are respectively delta T'1And Δ T'2Due to T'sT′f100 ℃ by assuming Δ T'1＝0.7ΔT′2To determine the position of the straight line p;
the fourth step: t 'is filtered'sThe point is taken as a perpendicular o, and the perpendicular o intersects with a differential curve of the phase-change volume fraction at a point A4Differential curve A of phase change volume fraction4A1Segment and TsA4The segments are respectively defined as curves m2And m3(ii) a Per A4Dotted horizontal line l3，l3Has a ordinate of P2Through the ordinate
Figure BDA0002361524490000082
P2Position as horizontal line l4Horizontal line l4And curve m3Cross over at point A5；
The fifth step: through a curved section m2And a straight line p, curve q: curve m2The vertical coordinate values corresponding to the straight line p and the curve q satisfy the relation q + p ═ m2(ii) a Curve q and horizontal line l4And l are crossed at the point A6And Tf，A5Point sum A6The vertical distances of the points from the perpendicular o are respectively Delta T1And Δ T2. Due to TsTfAbout 50 ℃ by slightly adjusting A1Position of dot, finally obtaining Delta T'1＝0.72ΔT′2And Δ T1＝0.82ΔT2And meeting the drawing condition.
And a sixth step: measuring the first wave S1And a second wave S2Area (S) in the figure1From horizontal line l, curve m3And curve q enclose, S2From horizontal line l, curve m1And a straight line p), the area ratio of the two is the volume ratio of the two phases which are successively converted, i.e.
Figure BDA0002361524490000091
In conclusion, the method obtains the volume ratio of the two phases by measuring the area in the graph through a certain plotting rule by measuring the numerical differential curve of the volume fraction of the phase change obtained by measuring the data of the thermal expansion amount of the low-alloy high-strength steel along with the temperature change in the two-phase transformation process; the method can solve the problem of calculating the volume fraction of each phase when the phase change temperature intervals are partially overlapped, and has the advantages of simple operation method and smaller calculation error.
Therefore, the invention enriches the application of the expansion lever method, is suitable for the condition when the two phases of the low-alloy high-strength steel are overlapped in partial temperature intervals, and can reduce the calculation error of the prior method. Meanwhile, the method can be used for calculating the volume ratio of three phases or multiple phases of the low-alloy high-strength steel.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (7)

1. A method for measuring the volume ratio of two phases of continuous cooling of low-alloy high-strength steel is characterized in that a thermal expansion curve of the low-alloy high-strength steel in the two-phase conversion process of continuous cooling is measured; carrying out lever method processing on a thermal expansion curve measured in the process of continuously cooling two phases of the low-alloy high-strength steel to obtain a phase change volume fraction curve; carrying out numerical differentiation on the phase change volume fraction curve to obtain a numerical differentiation curve of the phase change volume fraction; two overlapped waves on a numerical differential curve of the volume fraction of the phase change are separated through a plotting rule, and the area ratio of the two waves is the volume ratio of the two phase transition by measuring the areas of the two separated waves.
2. The method according to claim 1, characterized in that it is carried out in particular according to the following steps:
s1, obtaining test data of the thermal expansion amount corresponding to the temperature change of the low-alloy high-strength steel in the continuous cooling two-phase transformation process by using a test device;
s2, drawing a thermal expansion curve of the thermal expansion amount corresponding to the temperature change by taking the temperature as an abscissa and the thermal expansion amount as an ordinate according to the test data of S1;
s3, extending the linear change parts at the two ends of the curve of S2, carrying out lever method processing to obtain data of the total phase change volume fraction corresponding to temperature change, and drawing a phase change volume fraction curve;
s4, after the data of S3 are subjected to differential processing, a numerical differential curve of the phase change volume fraction corresponding to temperature change is made by taking the temperature as an abscissa and the differentiated data as an ordinate;
s5, according to the numerical differential curve of the phase change volume fraction obtained in the S4, the two overlapped waves on the curve are separated by adopting a drawing rule of separating the two overlapped waves on the curve, the areas of the two waves are measured, and the area ratio of the two waves is the volume ratio of the two phases which are converted in sequence.
3. The method according to claim 2, wherein the data acquisition in S1 is performed at a temperature interval of 0.01-0.1 ℃, a temperature data accuracy of 0.01-0.1 ℃, and a material thermal expansion data accuracy of 0.01-0.1 μm.
4. The method of claim 2, wherein the step of leveraging in S3 is: the curve of the thermal expansion amount corresponding to the temperature change is divided into 3 parts which are respectively approximate straight line parts D before phase change1(T), Curve D in the phase transition2(T) and a substantially linear portion D after phase transition3(T)；
Fitting the thermal expansion curve before and after phase change to obtain a straight line D1(T) and D3(T); calculating the phase change volume fraction of the phase change temperature interval as
Figure FDA0002361524480000021
Wherein T isiFor thermal simulation testSetting recorded temperature data, TsStarting temperature, T, of the overall phase transitionf' end temperature of the overall phase transition, D2(Ti) Amount of thermal expansion, f (T), recorded for a thermal simulation test apparatusi) The data of the phase change volume fraction corresponding to the temperature change is obtained;
the data acquisition method of the numerical differential curve of the phase change volume fraction corresponding to the temperature change comprises the following steps:
Figure FDA0002361524480000022
wherein f (T)i+1) Is at a temperature Ti+1Fractional value of time-phase change volume, Ti+1Is TiThe next recorded temperature.
5. The method of claim 2, wherein the mapping rule in S5 comprises the steps of:
s51, representing the differential curve of the phase change volume fraction into two mutually overlapped waves which respectively correspond to the first phase and the second phase; the start point of the first wave and the end point of the second wave correspond to the start temperature T of the first phase transitionsThe end temperature T of the second phase transitionf'; on this graph, a horizontal line l corresponding to the vertical mark 0 is drawn, which intersects the differential curve of the phase change volume fraction at TsAnd Tf' Point;
s52, according to the characteristics of the curve, assuming the wave trough of the second wave to be A1Point, passing A1Dotted vertical line o' and horizontal line l1，l1Has a ordinate of P1Through the ordinate
Figure FDA0002361524480000023
Position as horizontal line l2(ii) a Differential curve T of phase change volume fractionf′A1The segment is defined as curve m1Horizontal line l2And curve m1Cross over at point A2；
S53 differential curve A of phase change volume fraction1A2Segments were fitted with straight segment p ', extending p ' from perpendicular o 'Intersecting with the perpendicular line o 'as a symmetrical line to form an approximately symmetrical straight line p of the straight line p', the straight line p and the straight line l2And l are crossed at the point A3And Ts′，A3Point sum A2The vertical distances of the points from the perpendicular o' are respectively Delta T1' and Delta T2′，ΔT1' and Delta T2' need to satisfy a specific condition relationship DeltaT1′＝aΔT2′；
S54, passing Ts' Point is taken as the perpendicular o, which intersects the differential curve of the phase change volume fraction at the point A4Differential curve A of phase change volume fraction4A1Segment and TsA4The segments are respectively defined as curves m2And m3(ii) a Per A4Dotted horizontal line l3，l3Has a ordinate of P2Through the ordinate
Figure FDA0002361524480000031
Position as horizontal line l4Horizontal line l4And curve m3Cross over at point A5；
S55 passing through curve segment m2And a straight line p, curve q: curve m2The vertical coordinate values corresponding to the straight line p and the curve q satisfy the relation q + p ═ m2(ii) a Curve q and horizontal line l4And l are crossed at the point A6And Tf，A5Point sum A6The vertical distances of the points from the perpendicular o are respectively Delta T1And Δ T2Requires Δ T1And Δ T2Also satisfies a specific conditional relationship Δ T1＝aΔT2If Δ T1And Δ T2If the value of (A) fails to satisfy the specific condition relationship, the second valley point A is adjusted1Positions on a differential curve of the phase change volume fraction until all the above positional relationships are satisfied;
s56, measuring the first wave S1And a second wave S2In the figure, the area ratio of the two phases is the volume ratio of the two phases which are successively transformed.
6. The method of claim 5, wherein the method is performed in a batch processCharacterized in that when the line segment T iss′Tf' or TsTfWhen the lengths in the figure are respectively 150-100 ℃, 100-50 ℃ and 50-20 ℃, the delta T1′＝aΔT2' or Delta T1＝aΔT2The a is 0.65 + -0.05, 0.75 + -0.05 and 0.85 + -0.05 respectively.
7. The method of claim 5, wherein S is1From horizontal line l, curve m3And curve q enclose, S2From horizontal line l, curve m1And a straight line p.
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