CN108459149B - Method for rapidly analyzing impact fracture defect of ultra-deep drawing steel plate - Google Patents

Abstract

The invention relates to a method for rapidly analyzing the cracking defect of an ultra-deep drawing steel plate. The cut steel plate for forming is evenly divided into N fan-shaped areas with the center point of the steel plate as the center of the circle. M is divided into equal parts, the hardness value is measured at each divided point, then the deviation of the extreme value of hardness and the influence factor are calculated, and finally it is judged whether the steel plate has the possibility of punching or ear defects; the N and M are all integers. The advantage is that the strength of the steel plate can be indirectly assessed through the hardness test, and the hardness test is fast and takes less time. Therefore, through the hardness test of each point of the steel plate, the "microscopic" strength of each point is indirectly tested, so as to quickly test the anisotropic trend of the formed steel plate, which saves time, high efficiency, and also saves resources.

Description

A method for rapid analysis of punching defects in ultra-deep-drawing steel plates

technical field

The invention relates to a method for rapidly analyzing the cracking defect of an ultra-deep drawing steel plate.

Background technique

With the continuous expansion of the application fields of deep-drawn steel plates, industries such as compressor casings, enamel products, automobiles, and food packaging are gradually increasing the application ratio of deep-drawn steel plates.

Deep-drawing steel plates are required to have good surface quality and deep-drawing properties during the stamping process, especially for ultra-deep-drawing steel plates. In the process of stamping and forming, defects such as punching or ear making often occur. How to analyze and judge the advantages and disadvantages of the formed steel plate performance And the potential possibility of punching during stamping forming is of great practical significance.

At present, when the deep-drawing steel plate has cracking and ear-making defects during the stamping process, the commonly used analysis method is to take samples on site to test and compare the mechanical properties such as yield strength, tensile strength, elongation, n value and r value. Then carry out metallographic sample preparation, and finally carry out comprehensive mechanical property analysis and metallographic structure analysis, and give comprehensive conclusions. An analysis usually takes a week. If it is due to equipment and other reasons, it may take half a month to complete an analysis. At the same time, due to the uncertainty in the selection of mechanical properties and metallographic sampling points, the analysis results may sometimes have certain deviations.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide an intuitive and accurate method for quickly analyzing the cracking defects of ultra-deep-drawing steel plates. According to the positive correlation between hardness and strength, the strength of the steel plate can be indirectly evaluated through the detection of hardness. Therefore, , Through the hardness test of each point of the steel plate, the "microscopic" strength of each point is indirectly tested, so as to quickly test the anisotropic trend of the formed steel plate.

To achieve the above object, the present invention is achieved through the following technical solutions:

A method for quickly analyzing the cracking defects of ultra-deep-drawing steel plates. The cut steel plate for forming is evenly divided into N fan-shaped areas with the center point of the steel plate as the center of the circle, and the center line of each fan-shaped area is divided into M equal parts. , measure the hardness value at each equal point, then calculate the hardness extreme value deviation and influence factor, and finally judge whether the steel plate has the possibility of punching or ear defects; the N and M are all integers.

The value range of N is 6-12, and the value range of M is 2-5.

When testing the hardness value of each equal point, when the thickness of the steel plate is greater than or equal to 2.5mm, the Rockwell hardness tester is used for the hardness test; when the thickness of the steel plate is less than 2.5mm, the Vickers hardness tester is used for the hardness test.

Compute the hardness extreme deviation and mean:

or

是洛氏硬度极值偏差；In formula (1): HRBmax is the maximum Rockwell hardness value detected at each detection point when the thickness of the steel plate is ≥2.5mm; HRBmin is the minimum Rockwell hardness value detected at each detection point when the thickness of the steel plate is ≥2.5mm;

is the Rockwell hardness extreme deviation;

In formula (2): HRB _average is the average value of Rockwell hardness of each detection point;

是维氏硬度极值偏差；In formula (3): HVmax is the maximum Vickers hardness value detected at each detection point when the thickness of the steel plate is less than 2.5mm; HVmin is the minimum Vickers hardness value detected at each detection point when the thickness of the steel plate is less than 2.5mm;

is the deviation of the extreme value of Vickers hardness;

In formula (4): HV _average is the average value of Vickers hardness of each detection point;

Calculate the hardness influence factor K:

or

Analyze the possibility of punching or ear defects in steel plates:

When K<10%, there is no risk of punching or ear defects in the steel plate used for forming;

When 10%≤K<25%, the steel plate used for forming has the risk of punching or ear defects;

When K≥25%, the anisotropy of the microstructure of the steel plate used for forming is obvious, and punching or ear defects are very likely to occur.

Use a marker to mark the detection points higher than the average hardness value and lower than the average hardness value, respectively, to obtain the hardness distribution map of the steel plate used for forming.

Compared with the prior art, the beneficial effects of the present invention are:

The principle of the present invention is that the hardness is positively correlated with the strength, and the strength of the steel plate can be indirectly evaluated through the detection of the hardness, and the detection speed of the hardness is fast and time-consuming. Therefore, through the hardness test of each point of the steel plate, the "microscopic" strength of each point is indirectly tested, so as to quickly test the anisotropic trend of the formed steel plate, which saves time, high efficiency, and also saves resources. In addition, the present invention can also assist in the detection and analysis of mechanical properties and metallography, and provide the selection of appropriate analysis sites for them, which has a very broad application prospect.

Description of drawings

FIG. 1 is a metallographic structure diagram of Example 1. FIG.

FIG. 2 is a metallographic structure diagram of Example 2. FIG.

FIG. 3 is a metallographic structure diagram of Example 3. FIG.

FIG. 4 is a metallographic structure diagram of Example 4. FIG.

FIG. 5 is a metallographic structure diagram of Example 5. FIG.

FIG. 6 is a hardness distribution diagram of Example 5. FIG.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings, but it should be pointed out that the implementation of the present invention is not limited to the following embodiments.

The method of quickly analyzing the cracking defects of ultra-deep-drawing steel plates is to divide the cut steel plate for forming into N fan-shaped areas with the center point of the steel plate as the center of the circle, and divide the center line of each fan-shaped area into M equal parts. Measure the hardness value at each equal point, then calculate the hardness extreme value deviation and influence factor, and finally judge whether the steel plate has the possibility of punching or ear defects; N and M are both integers, and the value of N ranges from 6 to 12 , and the value of M ranges from 2 to 5.

When testing the hardness value of each equal point, when the thickness of the steel plate is greater than or equal to 2.5mm, the Rockwell hardness tester is used for the hardness test; when the thickness of the steel plate is less than 2.5mm, the Vickers hardness tester is used for the hardness test.

In the embodiment, the value range of N and M and the measurement results of hardness extreme values are shown in Table 1, the hardness extreme value difference and mean value results of stamped steel sheets are shown in Table 2 below, and the influencing factors and metallographic analysis are shown in Table 3.

Table 1 Values of N and M and the measurement results of extreme hardness values

Table 2 Hardness extreme difference and average result of steel plate

The test steel sheets of Examples 1-5 are SPHE hot-rolled and pickled sheets for refrigerator compressor casings.

Table 3 Hardness influencing factors and metallographic analysis

From Table 1 to Table 3, it is shown that the steel sheets of Examples 1 and 3 have the best performance, and the stamping results are consistent with the metallographic structure analysis. In Examples 4 and 5, the hardness influencing factor exceeds the standard, and the stamping results are punched and bottomed. It is also consistent with its metallographic structure, and in Example 2, the hardness influencing factor is in a transitional state. In fact, the selection of the metallographic analysis part also refers to the hardness distribution map of the steel plate. Referring to Fig. 5, as shown in the hardness distribution diagram of Example 5, the deep-drawing part is reasonably selected according to the hardness distribution diagram.

Claims (3)

1. a method for quick analysis of ultra-deep-drawing steel plate punching defects, it is characterized in that, the steel plate used for forming after trimming, with the center point of the steel plate as the center of the circle, is evenly divided into N fan-shaped areas, to each fan-shaped area. The center line is divided into M, and the hardness value is measured at each divided point, and then the hardness extreme value deviation and influence factor are calculated, and finally it is judged whether the steel plate has the possibility of punching or ear defects; the N and M are both integer; When testing the hardness value of each equal point, when the thickness of the steel plate is greater than or equal to 2.5mm, the Rockwell hardness tester is used for the hardness test; when the thickness of the steel plate is less than 2.5mm, the Vickers hardness tester is used for the hardness test; Compute the hardness extreme deviation and mean: ⊿HRB＝∣HRBmax－HRBmin∣ (1)

Or ⊿HV＝∣HVmax－HVmin∣ (3)

In formula (1): HRBmax is the maximum Rockwell hardness value detected at each detection point when the thickness of the steel plate is ≥2.5mm; HRBmin is the minimum Rockwell hardness value detected at each detection point when the thickness of the steel plate is ≥2.5mm; ⊿HRB is the Rockwell hardness extreme value deviation; In formula (2): HRB _average is the average value of Rockwell hardness of each detection point; In formula (3): HVmax is the maximum Vickers hardness value detected at each detection point when the thickness of the steel plate is less than 2.5mm; HVmin is the minimum Vickers hardness value detected at each detection point when the thickness of the steel plate is <2.5mm; ⊿HV is the deviation of the extreme value of Vickers hardness; In formula (4): HV _average is the average value of Vickers hardness of each detection point; Calculate the hardness influence factor K: K=⊿HRB/HRB _average =∣HRBmax－HRBmin∣/HRB _average ×100% (5) Or K=⊿HV/HV _average =∣HVmax－HVmin∣/HV _average ×100% (6) Analyze the possibility of punching or ear defects in steel plates: When K<10%, there is no risk of punching or ear defects in the steel plate used for forming; When 10%≤K<25%, the steel plate used for forming has the risk of punching or ear defects; When K≥25%, the anisotropy of the microstructure of the steel plate used for forming is obvious, and punching or ear defects are very likely to occur. 2 . The method for rapidly analyzing punching defects of an ultra-deep-drawing steel plate according to claim 1 , wherein the value range of N is 6-12, and the value range of M is 2-5. 3 . 3. a kind of method for quick analysis of ultra-deep-drawing steel plate punching defect according to claim 1, is characterized in that, use a marker to mark the detection point higher than hardness mean value and lower than hardness mean value respectively, obtain for The hardness profile of the formed steel sheet.

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