CN113061692A - Normalizing pretreatment process for forged wear-resistant steel balls for mining large-scale semi-autogenous mill - Google Patents
Normalizing pretreatment process for forged wear-resistant steel balls for mining large-scale semi-autogenous mill Download PDFInfo
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- CN113061692A CN113061692A CN202110302879.5A CN202110302879A CN113061692A CN 113061692 A CN113061692 A CN 113061692A CN 202110302879 A CN202110302879 A CN 202110302879A CN 113061692 A CN113061692 A CN 113061692A
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/28—Normalising
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/36—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for balls; for rollers
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
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Abstract
The invention discloses a normalizing pretreatment process for forged wear-resistant steel balls for mines of large-scale semi-autogenous mills, belonging to the technical field of material engineering; preparing round steel required by a forging ball according to the diameter of the wear-resistant steel ball, wherein the ratio of the diameter of the wear-resistant steel ball to the diameter of the round steel is 1.2-1.5: 1, and the ratio of the length of the round steel to the diameter of the wear-resistant steel ball is 1.6-2.4: 1; then, heating, forging and balling, normalizing, testing hardness and observing tissues are carried out on the round steel in sequence; the normalizing treatment method comprises the following steps: the normalizing process has high cooling speed, obviously refines the pearlite structure, shortens the normalizing time of the steel ball and improves the production efficiency of the steel ball; the cooling medium used in the invention is water, which is environment-friendly, pollution-free, recyclable and low in price; the normalizing process in the method increases the hardness and toughness matching property of the wear-resistant steel ball, can improve the wear resistance and impact toughness of the steel ball, prolongs the service life of the steel ball, and has obvious economic benefit.
Description
Technical Field
The invention relates to a normalizing pretreatment process for forged wear-resistant steel balls for mines of large-scale semi-autogenous mills, and belongs to the technical field of material engineering.
Background
Along with the large-scale and increased use amount of the mining semi-autogenous mill, the ton consumption of the large-diameter wear-resistant steel ball is increased, and the ore grinding production cost is increased, so that higher requirements on the toughness and hardness of the large-diameter wear-resistant steel ball are provided. At present, the failure modes of the large-diameter steel ball mainly comprise breakage, out of round, low wear resistance and the like, and the main reason is that the hard and tough contradiction of the steel ball exists. At present, the method for solving the contradiction mainly comprises adding alloy or rare earth elements, but the method can obviously improve the production cost of the wear-resistant steel ball and reduce the product competitiveness. According to the principle of reducing the original cost, fine grain strengthening is adopted, namely, the toughness of the steel ball is enhanced by refining grains while the hardness of the steel ball is kept. For the large-diameter wear-resistant steel ball, the comprehensive mechanical property is mainly determined by the size and the form of martensite. The smaller and finer the martensite form is, the higher the toughness of the steel ball while maintaining the high hardness. In addition, during the quenching of the alloy steel, austenite intragranular nuclei form martensite. The size of the martensite form is mainly determined by the size of austenite grains, and the smaller the austenite grains are, the finer the martensite form obtained by quenching is, so that the higher the toughness and the wear resistance of the wear-resistant steel ball is, and the longer the service life is.
In the traditional steel ball, after forging, the steel ball is quenched by waste heat, and under the heat treatment mode, temperature difference exists inside and outside the steel ball, so that the grain sizes of austenite inside and outside the steel ball are different, the internal structure of the quenched steel ball is not uniform, and particularly the size and the thickness of martensite needles are different. Therefore, the forged steel ball can be subjected to normalizing pretreatment and secondary heating and then quenched in order to obtain the martensite needle with uniform tissue distribution and fine shape. The purpose of normalizing is to refine pearlite, the smaller the pearlite lamellar spacing is, the more the ferrite and cementite phase interfaces are, so that the austenite nucleus part is increased in the secondary heating process of the steel ball, the austenite nucleation rate is increased, and the purpose of refining austenite is achieved; the secondary heating is to make the temperature inside and outside the steel ball more uniform.
The size of the pearlite sheet interlayer distance is related to the transition temperature and speed. In the pearlite transformation temperature range, the lower the transformation temperature, the faster the speed, and the smaller the pearlite lamellar spacing. In the prior art, the refined pearlite structure is mainly air-cooled through normalizing, but pearlite with finer lamellar spacing cannot be obtained due to low cooling speed, so that the cooling method is adopted, the cooling speed is increased, the supercooling degree is expanded, and the cooling time is controlled to achieve the purpose of refining the pearlite.
Disclosure of Invention
The invention provides a normalizing pretreatment process for the forged wear-resistant steel ball for the large-scale semi-autogenous mill mine aiming at the problem of the mismatching of the hardness and the toughness of the wear-resistant steel ball, compared with the traditional preparation method, the normalizing process in the method is environment-friendly, the used material water can be recycled, and the cost is low; in addition, the method can obviously refine the pearlite structure of the steel ball, shorten the normalizing time of the steel ball and improve the production efficiency.
The technical scheme adopted by the invention is as follows:
a large semi-autogenous mill mining wear-resistant steel ball post-forging normalizing pretreatment process is characterized by comprising the following steps:
(1) preparing round steel required by a forging ball according to the diameter of the wear-resistant steel ball, wherein the ratio of the diameter of the wear-resistant steel ball to the diameter of the round steel is 1.2-1.5: 1, and the ratio of the length of the round steel to the diameter of the wear-resistant steel ball is 1.6-2.4: 1;
(2) then, heating, forging and balling, normalizing, testing hardness and observing tissues are carried out on the round steel in sequence;
wherein, the heating treatment: the heating time is 6-7min, and the heating temperature is 1050-;
forging and balling: forging round steel at 1050-;
normalizing treatment: the method comprises two steps, wherein in the step 1), when the surface temperature of the steel ball is reduced to 850-880 ℃, water cooling is carried out, the water cooling temperature is about 30 ℃, the water cooling time is 10-20s, then water is discharged and air cooling is carried out, the surface temperature of the steel ball immediately after water discharge is 380-510 ℃, and the temperature after stabilization is 650-710 ℃; step 2): the steel ball after water outlet is cooled to room temperature by air, and the air cooling flow is not less than 870m3H, the air cooling time is 50-70 min;
and (3) hardness testing: after the steel ball is cooled to room temperature, linear cutting is used for sampling, and the hardness of the core bar is tested by a Rockwell hardness tester;
and (3) observing tissues: and (5) polishing, and observing the structure after the nitric acid and alcohol corrosion.
Further, the large-scale semi-autogenous mill mining wear-resistant steel ball post-forging normalizing pretreatment process is characterized in that the wear-resistant steel ball is prepared from the following raw materials in percentage by mass:
c: 0.52-0.71 wt.%, Si: 1.60-2.0 wt.%, Mn: 0.65-0.95 wt.%, Cr: 0.7-0.95 wt.%, the balance being Fe and unavoidable impurities.
Further, the large-scale semi-autogenous mill mining wear-resistant steel ball post-forging normalizing pretreatment process is characterized in that the diameter of the wear-resistant steel ball is 120-150 mm.
Compared with the traditional preparation method of the steel ball, the invention has the advantages that:
(1) the normalizing process has high cooling speed, obviously refines the pearlite structure, shortens the normalizing time of the steel ball and improves the production efficiency of the steel ball;
(2) the cooling medium used in the invention is water, which is environment-friendly, pollution-free, recyclable and low in price;
(3) the normalizing process in the method increases the hardness and toughness matching property of the wear-resistant steel ball, improves the wear resistance and impact toughness of the steel ball, prolongs the service life of the steel ball and has obvious economic benefit.
Drawings
Fig. 1 is an SEM image of an air-cooled plain steel ball in example 1.
Fig. 2 shows rockwell Hardness (HRC) of the air-cooled plain steel ball core strip of example 1.
FIG. 3 is an SEM image of a normalized water-cooled wearable steel ball in example 2 of the invention.
FIG. 4 shows the Rockwell Hardness (HRC) of the normalized water-cooled wear-resistant steel ball core strip of example 2 of the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments, but the scope of the present invention is not limited to the description.
Example 1:
as shown in figures 1 and 2, the normalizing pretreatment process for the mining common steel ball of the large semi-autogenous mill comprises the following steps:
(1) heating round steel with the diameter of 80mm and the length of 180mm by using a heating furnace, wherein the heating time is 6min, and the heating temperature is 1050 ℃.
(2) And (3) forging the round steel with the temperature of 1050 ℃, wherein the initial forging temperature is 1050 ℃, the forging time is 25s, and then cooling the forged steel ball in the air.
(3) After the steel ball is cooled to room temperature, firstly, linear cutting sampling is adopted, the average hardness of the core strip is measured to be 32HRC by a Rockwell hardness tester, and then the core strip is polished, corroded by nitric acid and alcohol, and then tissue observation is carried out.
(4) The sample structure is observed by adopting a scanning electron microscope under 10000 times, and the steel ball structure is found to be pearlite, and the lamella spacing is about 0.5 mu m.
Example 2:
as shown in FIGS. 3 and 4, the large-scale semi-autogenous mill mining wear-resistant steel ball after-forging normalizing pretreatment process comprises the following steps:
(1) heating round steel with the diameter of 80mm and the length of 180mm by using a heating furnace, wherein the heating time is 6min, and the heating temperature is 1050 ℃.
(2) Forging the round steel with the temperature of 1050 ℃, wherein the initial forging temperature is 1050 ℃, the forging time is 25s, then pre-cooling the forged steel ball, and normalizing when the temperature of the steel ball is reduced to 880 ℃.
(3) The normalizing treatment is divided into 2 stages:
1. when the surface temperature of the steel ball is reduced to 880 ℃, water cooling is carried out, the water cooling temperature is 30 ℃, the water cooling time is 10s, the surface temperature after water outlet is 506 ℃, and the temperature after stabilization is 708 ℃.
2. After the steel ball is cooled to room temperature by air, firstly, linear cutting sampling is adopted, the average hardness of the core strip is measured to be 33.8HRC by a Rockwell hardness tester, and then, the core strip is polished and corroded by nitric acid and alcohol for tissue observation.
3. The sample tissue is observed under 10000 times by adopting a scanning electron microscope, and the steel ball tissue is found to be troostite, the lamella spacing is about 0.1 mu m, and the steel ball tissue is obviously thinner than the air cooling tissue.
Compared with the steel ball prepared by the preparation method of the common steel ball, the steel ball tissue of the wear-resistant steel ball prepared by the method is obviously thinner than that of the common steel ball, the wear-resistant steel ball tissue can be obviously refined, the interlayer spacing of pearlite body slices reaches about 0.1 mu m, and the normalizing hardness of the steel ball is improved by about 1.8 HRC.
The above embodiments are only intended to illustrate the technical solution of the present invention and not to limit it, and although the present invention has been described in detail by the above embodiments, it will be understood by those skilled in the art that changes in form and detail may be made therein without departing from the scope of the present invention as defined by the appended claims.
Claims (3)
1. A large semi-autogenous mill mining wear-resistant steel ball post-forging normalizing pretreatment process is characterized by comprising the following steps:
(1) preparing round steel required by a forging ball according to the diameter of the wear-resistant steel ball, wherein the ratio of the diameter of the wear-resistant steel ball to the diameter of the round steel is 1.2-1.5: 1, and the ratio of the length of the round steel to the diameter of the wear-resistant steel ball is 1.6-2.4: 1;
(2) then, heating, forging and balling, normalizing, testing hardness and observing tissues are carried out on the round steel in sequence;
wherein, the heating treatment: the heating time is 6-7min, and the heating temperature is 1050-;
forging and balling: forging round steel at 1050-;
normalizing treatment: the method comprises two steps, wherein in the step 1), when the surface temperature of the steel ball is reduced to 850-880 ℃, water cooling is carried out, the water cooling temperature is about 30 ℃, the water cooling time is 10-20s, then water is discharged and air cooling is carried out, the surface temperature of the steel ball immediately after water discharge is 380-510 ℃, and the temperature after stabilization is 650-710 ℃; step 2): the steel ball after water outlet is cooled to room temperature by air, and the air cooling flow is not less than 870m3H, the air cooling time is 50-70 min;
and (3) hardness testing: after the steel ball is cooled to room temperature, linear cutting is used for sampling, and the hardness of the core bar is tested by a Rockwell hardness tester;
and (3) observing tissues: and (5) polishing, and observing the structure after the nitric acid and alcohol corrosion.
2. The process of claim 1, wherein the after-forging normalizing pretreatment process for the wear-resistant steel ball for the large-scale semi-autogenous mill mine is characterized in that the wear-resistant steel ball is prepared from the following raw materials in percentage by mass:
c: 0.52-0.71 wt.%, Si: 1.60-2.0 wt.%, Mn: 0.65-0.95 wt.%, Cr: 0.7-0.95 wt.%, the balance being Fe and unavoidable impurities.
3. The large-scale semi-autogenous mill mining wear-resistant steel ball post-forging normalizing pretreatment process as claimed in claim 1 or 2, wherein the diameter of the wear-resistant steel ball is 120-150 mm.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113953426A (en) * | 2021-10-19 | 2022-01-21 | 铜陵有色金神耐磨材料有限责任公司 | Manufacturing method of high-toughness mining wear-resistant steel ball |
| CN115927801A (en) * | 2022-12-09 | 2023-04-07 | 铜陵有色金神耐磨材料有限责任公司 | Heat treatment process for refining ferrous metal grains |
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| CN107574380A (en) * | 2017-10-30 | 2018-01-12 | 河北工业大学 | The big specification forging abrading-ball steel of high rigidity fine grain |
| CN108950385A (en) * | 2018-06-30 | 2018-12-07 | 河北工业大学 | Forge the big specification abrading-ball steel of low-cost and high-performance and its production method |
| CN110016541A (en) * | 2019-05-24 | 2019-07-16 | 东北大学 | A method of the GCr15 bearing ball annealing time is shortened by cooling controlling and rolling controlling process |
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2021
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| CN85104240A (en) * | 1985-04-14 | 1986-10-15 | 邯郸钢铁总厂 | Rolled steel balls for ball grinders using residual heat thermal treatment process and equipment |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113953426A (en) * | 2021-10-19 | 2022-01-21 | 铜陵有色金神耐磨材料有限责任公司 | Manufacturing method of high-toughness mining wear-resistant steel ball |
| CN115927801A (en) * | 2022-12-09 | 2023-04-07 | 铜陵有色金神耐磨材料有限责任公司 | Heat treatment process for refining ferrous metal grains |
| CN115927801B (en) * | 2022-12-09 | 2023-10-03 | 铜陵有色金神耐磨材料有限责任公司 | Heat treatment process for refining ferrous metal grains |
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