CN-122016502-A - Method for determining length of uniform temperature zone of high-temperature tensile sample

CN122016502ACN 122016502 ACN122016502 ACN 122016502ACN-122016502-A

Abstract

The invention relates to the technical field of material tests, in particular to a method for determining the length of a uniform temperature region of a high-temperature tensile sample, which comprises the steps of based on the characteristic that the sample generates necking in the high-temperature tensile process to enable the outer surface of the sample to present a certain taper, regarding the surface of the sample as a curved surface formed by rotating a curve corresponding to a quadratic function around a symmetrical axis of the curve, closely correlating the shape of the curved surface with the diameter of the original section of the sample in the necking region and the diameter of the original section of the sample, continuously changing the diameter of the section of the necking region correspondingly with the continuous change of the sample in the high-temperature state, finding out the functional relation between the tensile deformation and the uniform temperature region according to the constant volume of the deformation part of the sample before and after deformation, and accurately describing the uniform temperature region of the sample in the high-temperature tensile state, thus laying a good foundation for thermal simulation experiment operation and data analysis.

Inventors

ZHAO BAOCHUN
HUANG LEI
YUAN HUI
WANG XIAOFENG
LI GUANGLONG
XIE GUANGQUN

Assignees

鞍钢股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260209

Claims (4)

1. The method for determining the length of the uniform temperature zone of the high-temperature tensile sample is characterized by comprising the following steps of: S1, taking a rod-shaped tensile sample with a circular section for high-temperature tensile test until the sample is broken, wherein the radius of the circular section of the sample is Length of ; S2, establishing a rectangular coordinate system, namely selecting one of two sections of samples which are subjected to high-temperature stretching experiment breaking in the step S1, taking the straight line where the diameter of the fracture section circle is located as an x axis and the straight line where the axis of the sample is located as a y axis, and establishing the rectangular coordinate system; S3, determining the characteristic length; The total length of the two sections of samples after the high-temperature tensile test is The total elongation of the test piece after tensile fracture was Then Half of it is I.e. =2 Taking one of the two sections of fracture samples for analysis, wherein the difference between the length of the section and half of the elongation of the sample is the original length of the section before deformation, and the original length of the section before deformation is half of the length of the uniform temperature zone, and the section is set as The length of the soaking zone is 2 ; S4, calculating the length of the temperature equalizing region, namely breaking a curve of the side surface of the sample in the established rectangular coordinate system, rotating the curve around a symmetry axis to form a curved surface, and establishing a functional relation between the tensile deformation amount and the temperature equalizing region according to the rule that the volume of the sample part before and after deformation is unchanged: ; Wherein, the The radius of the section circle is the fracture position of a section of the sample after fracture after the selected high-temperature tensile sample is tested.
2. The method for determining the length of the uniform temperature region of a high-temperature tensile specimen according to claim 1, wherein the high-temperature tensile test is performed by welding a thermocouple at the middle position of a round rod-shaped tensile specimen, mounting the specimen on a thermal simulation tester for the high-temperature tensile test, heating the specimen to a set temperature, preserving the heat for a set time, and then stretching at the set stretching rate at the temperature until the specimen is broken, and collecting a force value and the stretched length and temperature parameters of the specimen during the test.
3. The method for determining the length of the homogeneous region of a high-temperature tensile specimen according to claim 1, wherein the curve of the side surface of the broken specimen in the established rectangular coordinate system has the following curve equation: ; Wherein, the Is a constant to be determined; The coordinates of the curve equation passing through two points are respectively ,0)、( , + ) Substituting the two data points into the curve equation to solve the undetermined constant : ; 。
4. The method for determining the length of the uniform temperature zone of a high-temperature tensile sample according to claim 1, wherein the rule that the volume of the sample participating in deformation before and after deformation is unchanged is as follows: ; The left end of the equation is a volume calculation formula of a half temperature equalizing area of the deformed sample, and the right end of the equation is a volume calculation formula of the deformed sample.

Description

Method for determining length of uniform temperature zone of high-temperature tensile sample Technical Field The invention relates to the technical field of material tests, in particular to a method for determining the length of a uniform temperature zone of a high-temperature tensile sample. Background The high-temperature tensile test can reflect the comprehensive influence of external force and temperature on the performance of the metal material. In scientific experiments or accident analysis, it is necessary to know the characteristic values, characteristic curves, such as maximum stress, true stress-true strain curves, etc., of the material at various temperatures. In general, however, the force values at various temperatures, engineering stress-strain curves, are obtained by tests, and it is difficult to analyze the causes of deformation and failure of the material. For example, in the continuous casting process of steel, surface cracks often occur in a casting blank in a specific temperature range, and the reason for the occurrence of the cracks needs to be analyzed according to the strength of the casting blank in the temperature range and the true stress-true strain curve of the casting blank under the tensile stress, so that the high-temperature tensile test result needs to be correspondingly converted, and the key of the conversion is the deformation form of the sample in the high-temperature tensile process, and the deformation form of the sample in the high-temperature tensile process is closely related to the temperature distribution inside the sample. At present, a thermal simulation testing machine and a material mechanics testing machine are mainly adopted to carry out high-temperature tensile test, and the high-temperature mechanical properties of the material are researched based on high-temperature tensile test data. Gleeble series thermal simulation testing machines are increasingly used in material research and consist of three major parts, namely a thermal system, a force system and a computer control system. The heating and cooling process in the material processing process can be accurately simulated through the thermal system of the Gleeble series thermal simulation tester, so that the Gleeble series thermal simulation tester is suitable for testing the high-temperature mechanical property and the phase change property of the metal material. In the thermal simulation process, the Gleeble series thermal simulation tester controls the heating speed of sample heating by controlling the current in the sample, and controls the cooling speed of the sample by adopting a clamp with good heat conduction performance and a cooling system. In fact, the temperature controlled in the thermal simulation test is the temperature at the section thermocouple welding point in the sample, and the temperature distribution in the sample is very uneven. The temperature equalizing area near the thermocouple is a key area in test analysis, and the size of the temperature equalizing area and influencing factors thereof are very important for thermal simulation experiment operation and data analysis. Accurate estimation of the sample soaking area is therefore required. Disclosure of Invention The invention provides a method for determining the length of a temperature equalizing region of a high-temperature tensile sample, which can accurately find out the temperature equalizing region of the sample in the high-temperature heating process and lays a foundation for thermal simulation experiment operation and data analysis. In order to achieve the above purpose, the invention is realized by adopting the following technical scheme: A method for determining the length of a uniform temperature zone of a high-temperature tensile sample comprises the following steps: s1, taking a rod-shaped tensile sample with a circular section for high-temperature tensile test, wherein the radius of the circular section of the sample is Length of ; S2, establishing a rectangular coordinate system, namely selecting one of two sections of samples which are subjected to high-temperature stretching experiment breaking in the step S1, taking the straight line where the diameter of the fracture section circle is located as an x axis and the straight line where the axis of the sample is located as a y axis, and establishing the rectangular coordinate system; S3, determining the characteristic length; The total length of the two sections of samples after the high-temperature tensile test is The total elongation of the test piece after tensile fracture wasThenHalf of it isI.e. =2Taking one of the two sections of fracture samples for analysis, wherein the difference between the length of the section and half of the elongation of the sample is the original length of the section before deformation, and the original length of the section before deformation is half of the length of the uniform temperature zone, and the section is set asThe leng