CN108459149B - Method for rapidly analyzing impact fracture defect of ultra-deep drawing steel plate - Google Patents
Method for rapidly analyzing impact fracture defect of ultra-deep drawing steel plate Download PDFInfo
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- CN108459149B CN108459149B CN201810446682.7A CN201810446682A CN108459149B CN 108459149 B CN108459149 B CN 108459149B CN 201810446682 A CN201810446682 A CN 201810446682A CN 108459149 B CN108459149 B CN 108459149B
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Abstract
The invention relates to a method for rapidly analyzing the punching crack defect of an ultra-deep drawing steel plate, which is characterized in that a cut steel plate for forming is uniformly divided into N fan-shaped areas by taking the center point of the steel plate as the center of a circle, the center line of each fan-shaped area is divided into M equal parts, the hardness value of each equal part is measured, then the deviation of the extreme hardness value and an influence factor are calculated, and finally whether the steel plate has the possibility of punching crack or ear-making defect is judged; n, M are integers. The advantages are that: the strength of the steel plate can be indirectly evaluated through hardness detection, and the hardness detection speed is high, and the time consumption is low. Therefore, the 'microscopic' strength of each point is indirectly tested through the hardness detection of each point of the steel plate, so that the anisotropy trend of the formed steel plate is quickly tested, the time and the efficiency are saved, and meanwhile, the resources are saved.
Description
Technical Field
The invention relates to a method for rapidly analyzing the punching crack defect of an ultra-deep drawing steel plate.
Background
With the continuous expansion of the application field of deep-drawing steel plates, the application proportion of deep-drawing steel plates is gradually increased in the industries of compressor shells, enamel products, automobiles, food packaging and the like.
The deep-drawing steel plate is required to have good surface quality and deep-drawing performance in the stamping process, particularly, the ultra-deep-drawing steel plate has the defects of punching cracks or lug making and the like frequently in the stamping forming process, and how to analyze and judge the quality of the performance of the formed steel plate and the potential possibility of the punching cracks in the stamping forming process has very important practical significance.
At present, when a deep-drawing steel plate has the defects of punching cracks and lug making in the punching process, the commonly adopted analysis method is field sampling, the detection and comparison of mechanical properties such as yield strength, tensile strength, elongation, n value, r value and the like are carried out, then metallographic sample making is carried out, and finally comprehensive mechanical property analysis and metallographic structure analysis are carried out to give a comprehensive conclusion. One analysis normally takes a week, and if for equipment reasons etc. it may sometimes be half a month before one analysis is completed. Meanwhile, uncertainty exists due to the selection of mechanical properties and sampling points of a metallographic phase, and a certain deviation may exist in an analysis result sometimes.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a method for intuitively, accurately and quickly analyzing the impact fracture defect of an ultra-deep drawing steel plate, wherein the strength of the steel plate can be indirectly evaluated through the detection of the hardness according to the positive correlation between the hardness and the strength, so that the 'microscopic' strength of each point is indirectly tested through the detection of the hardness of each point of the steel plate, and the anisotropy trend of the formed steel plate is quickly tested.
In order to achieve the purpose, the invention is realized by the following technical scheme:
a method for rapidly analyzing the punching crack defect of an ultra-deep drawing steel plate comprises the steps of uniformly dividing a cut steel plate for forming into N fan-shaped areas by taking the center point of the steel plate as the center of a circle, carrying out M equal division on the center line of each fan-shaped area, measuring the hardness value of each equal division point, calculating the deviation of the extreme hardness value and an influence factor, and finally judging whether the steel plate has the possibility of punching crack or lug making defect; n, M are integers.
The value range of N is 6-12, and the value range of M is 2-5.
When the hardness value of each equant point is detected, when the thickness of the steel plate is more than or equal to 2.5mm, a Rockwell hardness meter is adopted for hardness detection; and when the thickness of the steel plate is less than 2.5mm, a Vickers hardness meter is adopted for hardness detection.
And (3) calculating the deviation and the mean value of the extreme hardness value:
or
In formula (1): HRBmax is the maximum Rockwell hardness value detected in each detection point when the thickness of the steel plate is more than or equal to 2.5 mm; HRBmin is the minimum Rockwell hardness value detected in each detection point when the thickness of the steel plate is more than or equal to 2.5 mm;
is the rockwell hardness extreme deviation;
in formula (2): HRBAverageIs the Rockwell hardness mean value of each detection point;
in formula (3): HVmax is the maximum Vickers hardness value detected at each inspection point when the thickness of the steel sheet is < 2.5 mm; HVmin is the minimum Vickers hardness value detected in each detection point when the thickness of the steel plate is less than 2.5 mm;
is the deviation of the extreme value of Vickers hardness;
in formula (4): HV (high voltage) deviceAverageIs the average value of Vickers hardness of each detection point;
calculating a hardness influence factor K:
or
Analyzing the possibility of the steel plate having the crack or the ear defect:
when K is less than 10%, the steel plate for forming has no risk of impact cracking or ear making defects;
when K is more than or equal to 10% and less than 25%, the steel plate for forming has the risk of impact fracture or ear-making defect;
when K is more than or equal to 25 percent, the microstructure anisotropy of the steel plate for forming is obvious, and the punching crack or the lug making defect is likely to occur.
And marking the detection points which are higher than the hardness average value and lower than the hardness average value by using a marking pen respectively to obtain a hardness distribution diagram of the steel plate for forming.
Compared with the prior art, the invention has the beneficial effects that:
the invention is based on the principle that the hardness and the strength are in positive correlation, the strength of the steel plate can be indirectly evaluated through hardness detection, and the hardness detection speed is high and the time consumption is low. Therefore, the 'microscopic' strength of each point is indirectly tested through the hardness detection of each point of the steel plate, so that the anisotropy trend of the formed steel plate is quickly tested, the time and the efficiency are saved, and meanwhile, the resources are saved. In addition, the invention can assist the detection and analysis of mechanical property and metallographic phase, provides the selection of proper analysis part for the detection and analysis, and has very wide application prospect.
Drawings
FIG. 1 is a metallographic structure diagram of example 1.
FIG. 2 is a metallographic structure diagram of example 2.
FIG. 3 is a metallographic structure chart of example 3.
FIG. 4 is a metallographic structure chart of example 4.
FIG. 5 is a metallographic structure chart of example 5.
FIG. 6 is a hardness profile of example 5.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings, but it should be noted that the present invention is not limited to the following embodiments.
A method for rapidly analyzing the punching crack defect of an ultra-deep drawing steel plate comprises the steps of uniformly dividing a cut steel plate for forming into N fan-shaped areas by taking the center point of the steel plate as the center of a circle, dividing the center line of each fan-shaped area into M equal parts, measuring the hardness value of each equal part, calculating the deviation of the extreme hardness value and an influence factor, and finally judging whether the steel plate has the possibility of punching crack or ear-making defect; n, M are integers, N ranges from 6 to 12, and M ranges from 2 to 5.
When the hardness value of each equant point is detected, when the thickness of the steel plate is more than or equal to 2.5mm, a Rockwell hardness meter is adopted for hardness detection; and when the thickness of the steel plate is less than 2.5mm, a Vickers hardness meter is adopted for hardness detection.
The value range and hardness extreme value measurement results of N, M in the example are shown in table 1, the hardness extreme value difference and mean value results of the stamped steel plate are shown in table 2, and the influence factors and metallographic analysis are shown in table 3.
TABLE 1 values of N, M and hardness extreme measurements
TABLE 2 hardness extreme difference and mean value results for steel sheets
The test steel sheets of examples 1-5 were SPHE hot-rolled pickled sheets for refrigerator compressor housings.
TABLE 3 hardness influencing factor and metallographic analysis
As shown in tables 1 to 3, the steel sheets of examples 1 and 3 had the best properties, and the punching results and metallographic structure analysis were consistent, examples 4 and 5 had excessive hardness-affecting factors, and the punching results were also consistent in terms of chipping and metallographic structure analysis, whereas example 2 had hardness-affecting factors in a transient state. In fact, the metallographic section is also selected with reference to the hardness profile of the steel sheet. Referring to FIG. 5, the hardness profile of example 5 is used to select a suitable deep drawing portion.
Claims (3)
1. A method for rapidly analyzing the punching crack defect of an ultra-deep drawing steel plate is characterized in that a cut steel plate for forming is uniformly divided into N fan-shaped areas by taking the center point of the steel plate as the center of a circle, the center line of each fan-shaped area is divided into M equal parts, the hardness value of each equal part is measured, then the deviation of the extreme hardness value and an influence factor are calculated, and finally whether the steel plate has the possibility of punching crack or ear-making defect or not is judged; n, M are integers;
when the hardness value of each equant point is detected, when the thickness of the steel plate is more than or equal to 2.5mm, a Rockwell hardness meter is adopted for hardness detection; when the thickness of the steel plate is less than 2.5mm, a Vickers hardness meter is adopted for hardness detection;
and (3) calculating the deviation and the mean value of the extreme hardness value:
⊿HRB＝∣HRBmax－HRBmin∣ (1)
or (delta) HV | -HVmax-HVmin | (3)
In formula (1): HRBmax is the maximum Rockwell hardness value detected in each detection point when the thickness of the steel plate is more than or equal to 2.5 mm; HRBmin is the minimum Rockwell hardness value detected in each detection point when the thickness of the steel plate is more than or equal to 2.5 mm; Δ HRB is the Rockwell hardness extreme deviation;
in formula (2): HRBAverageIs the Rockwell hardness mean value of each detection point;
in formula (3): HVmax is the maximum Vickers hardness value detected at each inspection point when the thickness of the steel sheet is < 2.5 mm; HVmin is the minimum Vickers hardness value detected in each detection point when the thickness of the steel plate is less than 2.5 mm; Δ HV is the vickers hardness extremum deviation;
in formula (4): HV (high voltage) deviceAverageIs the average value of Vickers hardness of each detection point;
calculating a hardness influence factor K:
K＝⊿HRB/HRBaverage＝∣HRBmax－HRBmin∣/HRBAverage×100％ (5)
Or K ═ Δ HV/HVAverage＝∣HVmax－HVmin∣/HVAverage×100％ (6)
Analyzing the possibility of the steel plate having the crack or the ear defect:
when K is less than 10%, the steel plate for forming has no risk of impact cracking or ear making defects;
when K is more than or equal to 10% and less than 25%, the steel plate for forming has the risk of impact fracture or ear-making defect;
when K is more than or equal to 25 percent, the microstructure anisotropy of the steel plate for forming is obvious, and the punching crack or the lug making defect is likely to occur.
2. The method for rapidly analyzing the punching crack defect of the 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. The method for rapidly analyzing the die-cracking defect of the ultra-deep drawn steel plate as claimed in claim 1, wherein the detection points above the hardness mean value and below the hardness mean value are marked with a marker to obtain the hardness distribution map of the steel plate for forming.
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