CN-122016505-A - Calculation method for maximum strength of high-temperature stretching

CN122016505ACN 122016505 ACN122016505 ACN 122016505ACN-122016505-A

Abstract

The invention relates to the technical field of material tests, in particular to a method for calculating the maximum strength of high-temperature stretching, which comprises the steps of taking a rod-shaped stretching sample with a circular section for high-temperature stretching experiments, finding out the force value and the corresponding sample elongation in the same time when the maximum force value corresponds to the sample elongation, determining the total length of two sections of samples, the total elongation of the samples after stretching and breaking, the axial length of a selected section of necking area along the sample, the original length of the sample before deformation, calculating the maximum strength according to the minimum cross-sectional area of the necking area of the sample, accurately finding out the maximum force value born by the sample in the high-temperature stretching process and the minimum cross-sectional area of the sample corresponding to the maximum force value, and accurately calculating the maximum strength of the sample in the high-temperature stretching process.

Inventors

ZHAO BAOCHUN
HUANG LEI
YUAN HUI
JIN XING
MA HUIXIA

Assignees

鞍钢股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260209

Claims (3)

1. The method for calculating the maximum strength of high-temperature stretching 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, the maximum force value corresponds to the elongation of the sample; drawing a force time-varying curve under the same coordinate system according to the collected force value and the stretched length of the sample, and finding out the maximum force value in the same time when the stretched length of the sample is the same in time Corresponding sample elongation ; S3, determining parameters before and after deformation of the high-temperature tensile sample; the tensile sample is broken into two sections through a high-temperature tensile experiment, and the total length of the two sections of samples is When the test piece is broken by stretching, the total elongation is Then ; Taking one of the two broken samples for analysis, and measuring the length of the necking area along the axial direction of the sample as , Part of the sample involved in deformation, original length 2 before deformation Calculated from the following formula: 2 ; s4, calculating the minimum cross-sectional area of the sample necking zone: ; Wherein, the A minimum cross-sectional radius for the necked area of the sample; s5, calculating the maximum intensity: 。
2. The method for calculating the maximum strength of high-temperature tensile test according to claim 1, wherein the step S1 comprises the steps of taking a rod-shaped tensile test sample with a circular cross section, welding a thermocouple at the middle position of the test sample, and then installing the test sample on a thermal simulation tester for high-temperature tensile test, wherein the force value and the tensile length of the test sample are collected in the test process.
3. The method of claim 1, wherein the minimum cross-sectional radius of the necked area of the specimen is the specimen bearing capacity The radius of the smallest cross-section circle of the sample is calculated as follows: The test specimen is subjected to a force value of during high-temperature stretching When the elongation of the sample was When the bearing force value of the sample The radius of the smallest cross-sectional circle of the sample is The elongation of the sample at the side of the smallest cross-sectional circle was Taking a straight line where the diameter of the smallest cross-section circle is located as an x axis, taking a straight line where the axis of the sample is located as a y axis, and establishing a rectangular coordinate system, wherein an equation corresponding to a curve of the side surface of the sample on one side of the smallest cross-section circle in the established rectangular coordinate system is expressed as follows: ; Wherein, the Is a constant to be determined; The coordinates of the curve equation passing through two points are respectively ,0)、( , + ) Solving for the undetermined constant : ; ; According to the principle of calculus, and the tensile sample participating in the deformation part, the volume before and after deformation is unchanged, and the following formula is provided: ; the left end is a volume calculation formula of a deformed sample, the right end is a volume calculation formula of the deformed sample, and the minimum cross-section radius of a sample necking zone is obtained: 。

Description

Calculation method for maximum strength of high-temperature stretching Technical Field The invention relates to the technical field of material tests, in particular to a calculation method of high-temperature tensile maximum strength. 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 is 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, which requires corresponding transformation of the high-temperature tensile test result, and the key of transformation is the determination of the sectional area of the high-temperature tensile test sample. At present, a thermal simulation testing machine and a material mechanics testing machine are mainly adopted for high-temperature tensile test, the high-temperature mechanical properties of materials are researched based on high-temperature tensile test data, crack generation in the continuous casting process is performed, rolling force prediction is performed, and the like. The force sensor is embedded in the test equipment, so that the force value of the material in the whole test process can be directly obtained. However, the device is not equipped with a device capable of directly acquiring the change condition of the cross-sectional area of the material in the test process, and the tester can acquire parameters such as the temperature, the deformation, the force value, the stress value and the like of the material through corresponding sensors in the test process. For the stress value of one of important parameters in high-temperature tensile test data, the device can accurately acquire the load force value which can only be born by the sample, and the cross-sectional area of the sample which changes along with the tensile process is difficult to acquire, so that the deformation of the material is supposed to be uniform in the tensile process, but the deformation of the sample which occurs in the high-temperature tensile process is often uneven, so that the obtained stress under the assumption is inaccurate, and the more uneven the deformation of the sample is, the larger the deviation of the result is. The material tensile test data are obtained by a high-temperature tensile method, and on the basis of the data, the high-temperature mechanical properties of the material are researched, so that a calculation method of the maximum strength of the high-temperature tensile is required to be found. Disclosure of Invention The invention provides a calculation method of maximum strength of high-temperature stretching, which can accurately find out the maximum force value born by a sample in the high-temperature stretching process and the minimum cross-sectional area of the sample corresponding to the maximum force value, so as to accurately calculate the maximum strength of the sample in the high-temperature stretching process. In order to achieve the above purpose, the invention is realized by adopting the following technical scheme: A calculation method of maximum strength of high-temperature stretching 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, the maximum force value corresponds to the elongation of the sample; drawing a force time-varying curve under the same coordinate system according to the collected force value and the stretched length of the sample, and finding out the maximum force value in the same time when the stretched length of the sample is the same in time Corresponding sample elongation ; S3, determining parameters before and after deformation of the high-temperature tensile sample; the tensile sample is broken into two sections through a high-temperature tensile experiment, and the total length of the two sections of samples is When the test piece is broken by stretching, the total elongation isThen ; Taking one of the two broken samples for analysis, and measuring the length of the necking area along the axial direction of the sample as , Part of the sample involved in deformation, original length 2 before deformationCalculated from the following formula: 2 ; s4, calcu