CN115575201A

CN115575201A - Method for judging steel upset forging cracking factors

Info

Publication number: CN115575201A
Application number: CN202211089560.XA
Authority: CN
Inventors: 吴明安; 罗志俊; 侯栋; 桑海宁; 张鑫; 丁建国; 宋健; 郭金亮; 常瑜; 王开; 张成龙; 牛晓翠
Original assignee: Shougang Changzhi Iron and Steel Co Ltd
Current assignee: Shougang Changzhi Iron and Steel Co Ltd
Priority date: 2022-09-07
Filing date: 2022-09-07
Publication date: 2023-01-06

Abstract

The application relates to the technical field of steel products, and discloses a method for judging a steel product upsetting cracking factor. The method comprises the following steps: obtaining a steel product sample, and carrying out acid pickling on the steel product sample to be used as an acid pickling sample; inspecting the defects on the surface of the acid-washed sample, marking the positions of the defects and recording defect data; performing an upset forging test on the acid-washed sample to obtain an upset forging sample; checking whether the surface of the upset sample cracks or not, and if the surface of the upset sample cracks, acquiring a cracking position, a defect position and defect data; acquiring the cracking positions, the defect positions and the defect data corresponding to the plurality of steel samples, and analyzing the correlation degree of the plurality of defect positions, the defect data and the cracking positions. The crack positions, mark defect positions and defect data corresponding to a plurality of steel samples are obtained through a plurality of experiments, so that the correlation degree of certain surface defects or near surface defects and upset cracking is quantitatively analyzed, the optimization process control of a steel rolling production line is guided in a targeted manner, and the product quality is finally improved.

Description

Method for judging steel upset forging cracking factors

Technical Field

The application relates to the technical field of steel products, in particular to a method for judging an upsetting cracking factor of the steel products.

Background

Nowadays, the development of the super-grade steel is rapid in recent years, and the method makes a contribution to the economic development of China and the world. The high-quality steel is generally further processed into parts by downstream users, and the quality of the steel determines the mechanical life and safety. Taking fastener steel as an example, the dosage of the fastener steel in 2019 in China is over 1000 ten thousand tons, and accounts for about 45% of the total global production. The steel for the fastener is added with a radial upsetting forging process besides an axial drawing process in use, and the particularity and the strictness of the quality requirement of the steel are that a user uses the steel in the process to carry out 100 percent inspection on products so as to ensure the service life and the safety in mechanical connection.

Upset cracking is generally influenced by a plurality of factors, wherein defects on the surface or near the surface of the steel are main causes of the upset cracking of the steel. The formation reasons of the defects on the surface or near surface of the steel are complex, the influence degrees of various defects and the severity degrees of the defects on the upsetting cracking of the steel are different, the correlation degrees of different surface (near surface) defect types and the defect degrees on the upsetting cracking are researched, and qualitative and quantitative analysis is carried out to find out main defect influence factors, so that the method has important significance for guiding a steel rolling production line to carry out targeted improvement work and finally improving the product quality.

At present, partial scholars at home and abroad study whether the casting blank crack defect can be welded in a multi-pass rolling mode, but what degree the surface defect of which type has influence on the upsetting cracking of steel is specific to a certain production line? There is no intuitive experimental evidence for verification support.

Disclosure of Invention

The method aims to provide a method for judging the upsetting cracking factor of the steel, and the method is used for obtaining the cracking positions, the mark defect positions and the defect data corresponding to a plurality of steel samples through a plurality of experiments, so that the correlation degree of certain surface defects (near surface defects) and upsetting cracking is quantitatively analyzed, the optimization process control of a steel rolling production line is pertinently guided, and the product quality is finally improved.

Other features and advantages of the present application will be apparent from the following detailed description, or may be learned by practice of the application.

According to an aspect of the embodiments of the present application, there is provided a method for determining a cracking factor of upset forging of a steel material, the method further including: obtaining a steel product sample, and carrying out acid pickling on the steel product sample to be used as an acid pickling sample; inspecting the surface defects of the pickled sample, marking the defect positions and recording defect data; performing an upset forging test on the acid-washed sample to obtain an upset forging sample; checking whether the surface of the upsetting sample cracks or not, and if the surface of the upsetting sample cracks, acquiring a cracking position, a defect position and defect data; acquiring the cracking positions, the defect positions and the defect data corresponding to a plurality of steel samples, and analyzing the correlation degree of the defect positions, the defect data and the cracking positions.

In some embodiments, in the obtaining a steel sample, the method further comprises: and obtaining a steel product sample with a preset height higher than the ideal height.

In some embodiments, the predetermined height is between 1mm and 3 mm.

In some embodiments, after said inspecting the pickled sample surface for defects, marking defect locations and recording defect data, the method further comprises: sequentially carrying out coarse grinding, fine grinding and polishing on two ends of the steel sample; placing the steel sample on a metallographic microscope; and observing the steel sample, marking the defect position and recording defect data.

In some embodiments, the sequentially rough grinding, finish grinding, and polishing both ends of the steel sample further comprises sequentially rough grinding, finish grinding, and polishing both ends of the steel sample according to a metallographic sample preparation standard.

In some embodiments, the defect data packet defect type and defect size.

In some embodiments, the defect types include scratch defects, fold defects, crack defects, large inclusions, and gas hole defects.

In some embodiments, in the marking the defect location and recording the defect data, the method further comprises: and marking different defect types by using oil pens with different colors.

In some embodiments, in the upset sample after the subjecting the pickled sample to the upset test, the method further comprises: the upsetting test adopts 1/3 cold upsetting.

In some embodiments, in the obtaining the crack positions, the defect positions, and the defect data corresponding to the plurality of steel samples, and analyzing the correlation between the plurality of defect positions, the defect data, and the crack positions, the method further includes: and analyzing a plurality of defect positions and the correlation degree of the defect data and the crack positions by a statistical analysis method.

By the technical scheme of this application more than, compare with prior art, its beneficial effect that is showing lies in:

(1) According to the invention, by adopting the method of firstly pickling, then manufacturing a metallographic phase and then carrying out 1/3 cold upsetting, multiple test methods are adopted for the same sample, and the method is superior to the traditional test method. The traditional inspection test method has the defects that sample sampling positions are different, intermittent defects can be discovered by different experimental methods or cannot be discovered, and the influence of a certain defect on the upsetting performance can be realized, and the relevance of the defects can not be determined through the traditional pickling low-power inspection and the metallographic inspection. The invention completes three detection methods of acid washing sample preparation, metallographic phase sample preparation and cold upsetting single sample preparation on the same sample, and the causal relationship is more deterministic. The height of the sample is determined according to 1/3 of the cold upsetting height + (1-3 mm), and is different from the traditional metallographic sample and the acid-washed sample.

(2) According to the invention, the surface defect (near surface defect) part is marked in the radial direction and the axial direction, and the influence of the defect on the upset forging is judged more directly and accurately according to whether the marked part cracks after the upset forging, and the causal relationship is more determined; the method for marking different defects by different colors is adopted, so that the influence of different defects on top cracking can be more effectively identified.

(3) According to the invention, through a large-scale industrial production test, crack positions, mark defect positions and defect data corresponding to a plurality of steel samples are obtained, statistical analysis is carried out on the data, and the correlation degree of surface defects (near surface defects) to steel upsetting cracking can be finally obtained, so that the improvement process control of a steel rolling production line is pertinently guided, and the product quality is finally improved.

(4) The detection mode of the invention can replace macroscopic detection and metallographic detection, and reduce the detection workload.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

Drawings

The above and other features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

FIG. 1 shows a flow diagram according to one embodiment of the present application.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the application. One skilled in the relevant art will recognize, however, that the subject matter of the present application can be practiced without one or more of the specific details, or with other methods, components, devices, steps, and so forth. In other instances, well-known methods, devices, implementations, or operations have not been shown or described in detail to avoid obscuring aspects of the application.

The block diagrams shown in the figures are functional entities only and do not necessarily correspond to physically separate entities. I.e. these functional entities may be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different networks and/or processor means and/or microcontroller means.

The flow charts shown in the drawings are merely illustrative and do not necessarily include all of the contents and operations/steps, nor do they necessarily have to be performed in the order described. For example, some operations/steps may be decomposed, and some operations/steps may be combined or partially combined, so that the actual execution sequence may be changed according to the actual situation.

In order to make the present application better understood by those skilled in the art, the present application will be briefly described with reference to fig. 1.

According to some embodiments, the present application provides a method for determining a cracking factor of upset forging of a steel material, the method further comprising:

step 101, obtaining a steel product sample, and performing acid washing on the steel product sample to obtain an acid-washed sample;

step 102, detecting defects on the surface of the acid-washed sample, marking the positions of the defects and recording defect data;

103, performing an upset forging test on the acid-washed sample to obtain an upset forging sample;

104, checking whether the surface of the upset sample is cracked or not, and if the surface of the upset sample is cracked, acquiring a cracking position, a defect position and defect data;

and 105, acquiring the cracking positions, the defect positions and the defect data corresponding to the plurality of steel samples, and analyzing the correlation degree of the plurality of defect positions, the defect data and the cracking positions.

Based on the above embodiment, in step 101, a steel sample is obtained first, and the steel sample is pickled and then used as a pickled sample;

in step 102, the surface of the pickled sample after pickling is inspected for defects, the positions of the defects are marked, subsequent arrangement is facilitated, and defect data is recorded. The defect data packet comprises defect types and defect sizes, wherein the defect types comprise scratch defects, folding defects, crack defects, large inclusions, pore defects and the like, and the defect sizes comprise defect length degrees, defect depth degrees and the like. Different defect types are marked by adopting oil pens with different colors, so that the defect types are convenient to distinguish.

In step 103, the acid-washed sample is subjected to an upset test using 1/3 cold upset as an upset sample.

Further, the upset forging test includes cold upset forging and hot upset forging, the height of 1/3 cold upset forging is H according to the steel material with the standard required diameter d, compression is carried out on an upset forging testing machine along the height direction, the height after compression is H, H =1/3H is required, and when the steel material is compressed to the height, the steel material cannot crack. The upsetting also comprises 1/4 upsetting and 1/2 upsetting, and obviously, the quality requirement of the 1/4 upsetting on the steel is higher, and conversely, the quality requirement of the 1/2 upsetting on the steel is relatively lower. The general super steel is subjected to 1/3 cold or hot upset forging test. The difference between the cold upsetting and the hot upsetting is that the upsetting temperature of the material is different, the cold upsetting is performed at normal temperature, and the hot upsetting is performed by heating to a temperature above 900 ℃.

In step 104, after 1/3 cold upsetting is adopted, carefully checking whether the surface of the upset sample cracks, if the surface of the upset sample cracks, recording the crack position, the defect position and the defect data, and filling a record table.

In step 105, the steps 101 to 104 are repeated, the cracking positions, the defect positions and the defect data corresponding to a plurality of steel samples with cracking phenomena are obtained, and whether each different defect position and defect data are the cause of the upset forging cracking or not is analyzed, and the relationship between the defect position and the cracking position is determined. And analyzing a plurality of defect positions and the correlation degree of the defect data and the crack position by adopting a statistical analysis method.

Finally, the relevance of the surface defect (near surface defect) to the upset cracking of the steel is obtained, so as to pertinently guide the improvement of process control of the steel rolling production line and finally improve the product quality.

According to some embodiments, in step 101, a steel sample is obtained, the method further comprising:

and obtaining a steel product sample which is higher than the ideal height by a preset height. The ideal height is a height h required by a standard, the preset height can be set according to actual requirements, and in some embodiments, the preset height can be set to any value between 1mm and 3mm and set according to actual requirements. That is, in step 101, when a steel material sample is obtained, a steel material sample having a height h + a preset height is obtained. Through increasing and predetermine the height to when both ends need polish, there is certain reserve height. The height of the product is prevented from being shortened due to grinding when the reserved height is not reserved and the two ends of the product need to be ground.

According to some embodiments, after inspecting the pickled sample surface for defects, marking defect locations and recording defect data, at step 102, the method further comprises:

step 1021, performing coarse grinding, fine grinding and polishing on two ends of the steel sample in sequence;

step 1022, placing the steel sample on a metallographic microscope;

and 1023, observing the steel sample, marking the defect position and recording defect data.

Based on the above embodiment, in step 1021, according to the standard for making a metallographic sample, both ends of a steel sample are coarsely ground; and according to the standard of the metallographic sample, finely grinding and polishing both ends of the steel sample so as to facilitate subsequent observation through a microscope.

In step 1022, the steel sample is placed on a metallographic microscope, and the steel sample is rotated from a certain point along the circumferential direction of the cross section of the steel sample.

And step 1023, observing the steel sample, marking the defect position and recording defect data when a defect is encountered on the surface or the near surface of a certain position. And turning over the steel sample to continue observation, marking and recording, finishing the observation of the whole steel sample, marking all defect positions and recording all defect data. And different types of the defects are marked by adopting oil pens with different colors, so that the defects can be distinguished conveniently. Such as: green mark scratch defects, blue mark folding defects, yellow mark crack defects, black mark large inclusions, red mark air hole defects, and the like.

(1) The invention adopts a method of firstly pickling, then manufacturing a metallographic phase and then carrying out 1/3 cold upsetting on the same sample, and adopts a plurality of test methods on the same sample, which are superior to the traditional test method. The traditional inspection test method has the defects that sample sampling positions are different, intermittent defects can be discovered by different experimental methods or cannot be discovered, and the influence of a certain defect on the upsetting performance can be realized, and the relevance of the defects can not be determined through the traditional pickling low-power inspection and the metallographic inspection. The invention completes three detection methods of acid washing sample preparation, metallographic phase sample preparation and cold upsetting single sample preparation on the same sample, and the causal relationship is more deterministic. The height of the sample is determined according to 1/3 of the cold upsetting height + (1-3 mm), and is different from the traditional metallographic sample and the traditional acid washing sample.

(2) According to the invention, the surface defect (near surface defect) part is marked in the radial direction and the axial direction, and the influence of the defect on the upset forging is judged more directly and accurately according to whether the marked part cracks after the upset forging, and the causal relationship is more determined; the method for marking different defects by different colors can effectively identify the influence of different defects on top cracking.

(4) The inspection mode of the invention can replace the macroscopic inspection and the metallographic inspection, and reduce the inspection workload.

Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains.

It will be understood that the present application is not limited to the precise arrangements that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the application is limited only by the appended claims.

Claims

1. A method for determining a cracking factor in upset forging of a steel material, the method comprising:

obtaining a steel product sample, and carrying out acid pickling on the steel product sample to be used as an acid pickling sample;

inspecting the surface defects of the pickled sample, marking the defect positions and recording defect data;

performing an upset forging test on the acid-washed sample to obtain an upset forging sample;

checking whether the surface of the upsetting sample cracks or not, and if the surface of the upsetting sample cracks, acquiring a cracking position, a defect position and defect data;

acquiring the cracking positions, the defect positions and the defect data corresponding to a plurality of steel samples, and analyzing the correlation degree of the defect positions, the defect data and the cracking positions.

2. The method of claim 1, wherein in said obtaining a steel sample, said method further comprises:

and obtaining a steel product sample with a preset height higher than the ideal height.

3. The method according to claim 2, wherein the predetermined height is between 1mm and 3 mm.

4. The method of claim 1, wherein after said inspecting said pickled sample surface for defects, marking defect locations and recording defect data, said method further comprises:

sequentially carrying out coarse grinding, fine grinding and polishing on two ends of the steel sample;

placing the steel sample on a metallographic microscope;

and observing the steel sample, marking the defect position and recording defect data.

5. The method of claim 4, wherein in the sequentially rough grinding, finish grinding, and polishing both ends of the steel sample, the method further comprises:

and according to the standard of manufacturing a metallographic sample, sequentially carrying out coarse grinding, fine grinding and polishing on two ends of the steel sample.

6. The method of claim 4, wherein the defect data packet comprises a defect type and a defect size.

7. The method of claim 6, wherein the defect types include scratch defects, fold defects, crack defects, macro inclusions, and gas hole defects.

8. The method of claim 7, wherein in said marking a defect location and recording defect data, the method further comprises:

and marking different defect types by using oil pens with different colors.

9. The method of claim 1, wherein in the upset forging test of the pickled sample, the method further comprises:

the upsetting test adopts 1/3 cold upsetting.

10. The method of claim 1, wherein in said obtaining crack locations, defect locations, and defect data corresponding to a plurality of steel samples, and analyzing a correlation of a plurality of said defect locations, defect data, and said crack locations, said method further comprises:

and analyzing a plurality of defect positions and the correlation degree of the defect data and the crack positions by a statistical analysis method.