CN-122016503-A - Calculation method for elongation of high-temperature tensile sample

CN122016503ACN 122016503 ACN122016503 ACN 122016503ACN-122016503-A

Abstract

The invention relates to the technical field of high-temperature stretching experiments, in particular to a method for calculating the elongation of a high-temperature stretching sample, which comprises the steps of based on the characteristic that the sample generates necking in the high-temperature stretching 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 an original section of a sample necking area and the diameter of the original section of the sample, continuously changing the diameter of the section of the necking area to correspond to the sample under the high-temperature state along with the stretching, finding out a functional relation between the stretching deformation and the length before and after the deformation by the constant volume of the sample participation deformation part, accurately calculating the elongation, and laying a good foundation for thermal simulation experiment operation and data analysis.

Inventors

ZHAO BAOCHUN
HUANG LEI
YUAN HUI
MA HUIXIA
JIN XING
SUN CHENGQIAN

Assignees

鞍钢股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260209

Claims (4)

1. The method for calculating the elongation 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, 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 broken samples for analysis, wherein the difference between the length of the one section and half of the elongation of the sample is the original length of the one section before deformation, and the original length of the one section before deformation is half of the original length of the whole sample before deformation, and the two sections are set as The original length of the whole sample before deformation is 2 ; S4, calculating elongation, 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 obtaining a calculation formula of the elongation of the sample according to a rule that the volume of the sample 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 calculating the elongation of a high-temperature tensile specimen according to claim 1, wherein the performing the high-temperature tensile test comprises welding a thermocouple at the middle of a round rod-shaped tensile specimen, mounting the specimen on a thermal simulation tester for performing the high-temperature tensile test, heating the specimen to a set temperature, maintaining the temperature for a set time, and then stretching at the set stretching rate at the temperature until the specimen is broken, and collecting the force value and the stretched length of the specimen during the test.
3. The method for calculating the elongation 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 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 calculating the elongation 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: ; 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

Calculation method for elongation of high-temperature tensile sample Technical Field The invention relates to the technical field of high-temperature tensile experiments, in particular to a method for calculating the elongation 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, reduction of area, elongation, true stress-true strain curves, etc., of materials at various temperatures. According to the continuous casting process of the casting blank, a thermal simulation tester is generally adopted, a sample is heated to a higher temperature region, the sample is kept at the high temperature region for a period of time, then the sample is cooled to a certain temperature, finally the sample is stretched at a certain stretching rate at a high temperature until the sample is broken, and the cross section area of the broken sample is analyzed, so that the area shrinkage is obtained, and the plasticity performance of the casting blank in the continuous casting process is studied. However, the parameters reflecting the mechanical properties of plasticity are elongation after fracture in addition to the reduction of area, and for the measurement of elongation, the measurement of elongation is generally focused on the measurement of elongation of a tensile sample at room temperature, and because the material has certain fluidity in a high temperature state and the temperature distribution of the sample has certain gradient when the sample is heated by a thermal simulation tester, the sample is not deformed in the whole sample during tensile deformation, which is more obvious on the resistive thermal simulation tester. If the original length of the entire specimen is still used in calculating the elongation, a large error is necessarily generated. The patent with the application number 201110081820.4 is a clamping device for measuring the elongation after breaking and the reduction of area of a columnar tensile sample, the broken sample is centered and fastened together by designing a set of device, and then related measurement is carried out by adopting a vernier caliper. The problem that this patent solved is centering, fastening the sample for follow-up measurement, does not consider the temperature of sample in the length direction, the inhomogeneous problem of deformation. The method for measuring the elongation of the sample, which is measured by the rapid measuring device for the elongation after breaking and the reduction of area of the round sample with the patent number CN200620045221.1 and the auxiliary clamping device for measuring the elongation and the reduction of area of the sample with the patent number CN200820020540.6, is also limited to the calculation of the elongation of the tensile sample at room temperature, and the original length of the sample is also used in the calculation, so that larger deviation is caused when the elongation of the tensile sample at high temperature is calculated. Therefore, no effective measurement method has been currently available for calculation of the elongation of a high-temperature tensile sample. Because the high-temperature tensile sample has the characteristics of uneven temperature, uneven deformation and the like in a high-temperature state, the elongation of the sample cannot be calculated simply by dividing the difference between the length of the broken sample and the original length by the original length, and a more effective and accurate method for measuring the elongation of the high-temperature tensile sample is also required. Disclosure of Invention The invention provides a method for calculating the elongation of a high-temperature tensile sample, which can quickly and accurately find out the characteristic length of the sample before and after high-temperature tensile deformation, so that the elongation is accurately calculated, and a foundation is laid for analyzing high-temperature tensile data of the material. In order to achieve the above purpose, the invention is realized by adopting the following technical scheme: the method for calculating the elongation of the 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 establi