CN-121977921-A - Parallel test and minimum spacing compensation method for elongation after uniaxial stretching and breaking of plate

Abstract

The invention relates to the technical field of metal material tensile tests, in particular to a parallel test and minimum spacing compensation method for the elongation after uniaxial tensile breaking of a plate. The method comprises the steps of preparing a sample with the gauge length of L, carrying out equidistant marking, measuring the key mark distance at the fracture through at least two parallel tensile tests, selecting the minimum value of the key distance in all the tests as a compensation reference value, and calculating the corrected elongation after fracture by using the compensation reference value and a corresponding formula after the test under the same marking condition of the sample to be tested. The invention uses the core means of 'parallel test to determine the reference value + model compensation', on the premise of not changing the existing high-efficiency marking process, the system error caused by marking damage is corrected fundamentally, the accuracy and the authenticity of the measurement result are improved obviously, and the invention is convenient to integrate into the existing test system, and has high engineering practical value.

Inventors

• LIANG XIAO
• LU YANPENG
• XU XIN
• LIN LI
• LIU RENDONG
• ZHANG RUIKUN
• LI XIAOTONG
• LI CHUNLIN
• LIU WENBO
• LV DONG

Assignees

• 鞍钢股份有限公司

Dates

Publication Date

20260505

Application Date

20260112

Claims (5)

1. 1. The parallel test and minimum spacing compensation method for the elongation after uniaxial tension fracture of the plate is characterized by comprising the following steps of: Step 1, preparing a plate tensile sample with a gauge length L; Step 2, in the sample gauge length range, equidistant scribing is carried out by adopting a contact type marking tool to form a series of marks, wherein the mark distance D=L/X, and X is the distance number; step 3, carrying out a first tensile test on the marked sample until the sample is broken, and dividing the sample into Y, Z sections after the sample is broken; Step 4, measuring and recording key mark spacing on the broken sample: If the fracture occurs on the mark, measuring mark spacing at two sides of the fracture, and recording as Y1 and Z1, wherein Y1 and Z1 are key mark spacing; If the fracture occurs between two adjacent marks, splicing Y, Z sections, and measuring the distance YZ between the two marks after splicing, wherein YZ is the key mark distance; Step 5, repeating the parallel test of the steps 2 to 4 at least once; Step 6, selecting the minimum value of the key mark spacing in all parallel experiments, and marking the minimum value as compensation reference values Y1 min 、Z1 min and YZ min ; step 7, carrying out a tensile test on the sample to be tested under the same marking condition as the step 2, measuring the post-fracture gauge length as La, and calculating the corrected post-fracture elongation A according to the compensation reference value; if a break occurs in the tag: If a break occurs between two adjacent markers: 。
2. 2. The method for parallel testing and minimum spacing compensation of elongation after uniaxial stretching of a plate according to claim 1, wherein in the step 2, X is not less than 5 when L is not less than 50mm, X is not less than 1 when L is not less than 50mm, and the mark spacing D is not less than 1mm.
3. 3. The method for parallel testing and minimum spacing compensation of elongation after uniaxial stretching of a sheet according to claim 1, wherein in the step 2, the contact marking tool is a spike impact tool or a laser engraving tool.
4. 4. The method for parallel testing and minimum distance compensation of elongation after uniaxial stretching of a sheet according to claim 1, wherein the step 2 is marked as a dot or a line.
5. 5. The method for parallel testing and minimum spacing compensation of elongation after uniaxial stretching of a sheet according to claim 1, wherein the total number of parallel tests in step 5 is at least 3.

Description

Parallel test and minimum spacing compensation method for elongation after uniaxial stretching and breaking of plate Technical Field The invention relates to the technical field of metal material tensile tests, in particular to a parallel test and minimum spacing compensation method for the elongation after uniaxial tensile breaking of a plate. Background The uniaxial tensile test is a basic means for evaluating the mechanical properties of a metal plate, and the elongation after breaking is a key index for measuring the plasticity of the material. The index is obtained by presetting an original gauge length on the surface of the sample and measuring the elongation after fracture. Currently, two main technical routes are adopted in the industry to deal with the problem of gauge mark: the first is the "contact marking method", i.e., the use of a tool such as a spike impact, laser engraving, etc., to scribe directly marked points or lines on the surface of the sample. Although the method is high in efficiency, unavoidable micro damage and stress concentration are introduced on the surface of the material, so that the sample frequently breaks in advance at the marked position during stretching, the measured value of the elongation after breaking is systematically lower, and the real performance of the material is seriously underestimated. The second is "high precision or non-invasive measurement", such as with a non-contact optical strain measurement system (DIC). Although the method can avoid damage to the mark, the method has the advantages of expensive equipment, complex operation and high requirement on the test environment, and is difficult to popularize in conventional industrial detection and mass experiments. Therefore, the prior art falls into the dilemma that the high-efficiency traditional marking method can introduce errors, and the high-precision measuring method has high cost and low efficiency. The long-standing improvement ideas in the industry have been limited to "how to reduce the marking damage itself", such as optimizing the sharpness or energy of the marking instrument, but none of them can fundamentally eliminate the stress concentrating effect. Disclosure of Invention In order to overcome the defects of the prior art, the invention provides a parallel test and minimum spacing compensation method for the elongation after uniaxial stretching of a plate, which eliminates the influence of marking and scoring damage on the material performance on the basis of using a conventional marking and scoring tool, ensures the efficiency and greatly improves the accuracy of the measurement of the elongation after breaking. In order to achieve the above purpose, the invention is realized by adopting the following technical scheme: a parallel test and minimum spacing compensation method for elongation after uniaxial stretching of a plate comprises the following steps: Step 1, preparing a plate tensile sample with a gauge length L; Step 2, in the sample gauge length range, equidistant scribing is carried out by adopting a contact type marking tool to form a series of marks, wherein the mark distance D=L/X, and X is the distance number; step 3, carrying out a first tensile test on the marked sample until the sample is broken, and dividing the sample into Y, Z sections after the sample is broken; Step 4, measuring and recording key mark spacing on the broken sample: If the fracture occurs on the mark, measuring mark spacing at two sides of the fracture, and recording as Y1 and Z1, wherein Y1 and Z1 are key mark spacing; If the fracture occurs between two adjacent marks, splicing Y, Z sections, and measuring the distance YZ between the two marks after splicing, wherein YZ is the key mark distance; Step 5, repeating the parallel test of the steps 2 to 4 at least once; Step 6, selecting the minimum value of the key mark spacing in all parallel experiments, and marking the minimum value as compensation reference values Y1 min、Z1min and YZ min; step 7, carrying out a tensile test on the sample to be tested under the same marking condition as the step 2, measuring the post-fracture gauge length as La, and calculating the corrected post-fracture elongation A according to the compensation reference value; if a break occurs in the tag: If a break occurs between two adjacent markers: further, in the step 2, when L is more than or equal to 50mm, X is more than or equal to 5, and when L is less than 50mm, X is more than or equal to 1, and the mark distance D is not less than 1mm. Further, in the step 2, the contact marking tool is a spike impact tool or a laser engraving tool. Further, in the step 2, a dot or a line is marked. Further, the total number of parallel trials was at least 3. Compared with the prior art, the invention has the beneficial effects that: 1. The system error is corrected fundamentally, and the measurement accuracy and the authenticity are improved greatly. In the prior art, whether pointed-nail