CN109576637B - Carburizing method for hard alloy - Google Patents
Carburizing method for hard alloy Download PDFInfo
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- CN109576637B CN109576637B CN201811565659.6A CN201811565659A CN109576637B CN 109576637 B CN109576637 B CN 109576637B CN 201811565659 A CN201811565659 A CN 201811565659A CN 109576637 B CN109576637 B CN 109576637B
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/60—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using solids, e.g. powders, pastes
- C23C8/62—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using solids, e.g. powders, pastes only one element being applied
- C23C8/64—Carburising
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/24—After-treatment of workpieces or articles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
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Abstract
The invention discloses a carburizing method of hard alloy, which belongs to the field of hard alloy manufacturing, and adopts a dewaxing sintering integrated furnace or a pressure sintering furnace to replace a molybdenum wire hydrogen sintering furnace for carburizing and sintering, wherein the density of graphite particles is high, and the graphite particles are not easy to diffuse into a hearth or even into a vacuum pipeline in the carburizing and sintering process, do not damage the pipeline of the sintering furnace, and can not diffuse into the air to pollute the environment; the graphite particles are easy to separate from the hard alloy decarburization product, and are not easy to adhere to the surface of the hard alloy, so that the production efficiency is improved; the graphite boat is sealed by the graphite cover plate, graphite particles are further prevented from being dispersed into the inside of a hearth or even a vacuum pipeline, the graphite cover plate plays a key role in controlling carbon atmosphere in a carburizing process, carburizing treatment is effectively performed on hard alloy decarburized products, argon is introduced into the dewaxing and sintering integrated furnace or the pressure sintering furnace, certain pressure is controlled, the defect of hard alloy decarburizing is overcome, the process is short, and the production cost is low.
Description
Technical Field
The invention belongs to the field of hard alloy manufacturing, and particularly relates to a carburizing method for hard alloy.
Background
The carbon content is a key factor influencing the performance of the hard alloy, and the phase composition and the microstructure of the alloy can be changed due to slight carbon content fluctuation, so that the performance of the alloy is influenced. When the carbon content in the alloy is insufficient, a decarburization structure phase is easy to appear, and the phase is brittle and unstable, so that the strength of the alloy is reduced; when the carbon content in the alloy is higher, the interior of the alloy will generate free graphite, the existence of the graphite destroys the continuity of the alloy matrix, plays a certain role in cracking, and has adverse effects on the strength, toughness, wear resistance and the like of the alloy.
The control of the carbon content of the hard alloy is influenced by the factors of mixture preparation, glue mixing, brush cover and sintering of padding and burning coating in the manufacturing process of the hard alloy, so that the hard alloy product has carbon deficiency and carburization defects, and the carbon deficiency and carburization product needs to be supplemented with carbon and decarbonized through the subsequent carburization and decarbonization auxiliary process.
Carburizing and decarbonizing hard alloy products are generally completed by using a molybdenum wire hydrogen sintering furnace, and the molybdenum wire hydrogen sintering furnace is generally eliminated along with the development of manufacturing technology. At present, a hard alloy product carburizing method generally adopts a filling method to finish carburizing in a vacuum furnace, and under the condition of vacuumizing in a sintering process, graphite powder with lower density can be diffused into the interior of a hearth and even a vacuum pipeline, so that a sintering furnace is damaged and can be diffused into air to pollute the environment; meanwhile, the carbon atmosphere in the carburizing process is not well controlled in a vacuum state at the sintering temperature, the carburizing effect is not obvious, and the defective rate of cemented carbide after carburizing is increased.
Disclosure of Invention
In view of the shortcomings of the prior art, the invention aims to provide a carburizing method for hard alloy with simple process and low cost, which adopts sealed graphite particles as a filler in a dewaxing and sintering integrated furnace or a pressure sintering furnace, can prevent graphite powder from flying to damage the sintering furnace, and can effectively perform carburizing treatment on hard alloy decarburized products by keeping a certain atmosphere pressure.
The invention provides a carburizing method of hard alloy, which comprises the following steps:
(1) uniformly laying graphite particles in a graphite boat, filling the hard alloy decarburization product into the graphite particles, and sealing the graphite boat by using a graphite cover plate to obtain an assembled hard alloy and graphite assembly;
(2) putting the assembled hard alloy and graphite assembly obtained in the step (1) into a dewaxing and sintering integrated furnace or a pressure sintering furnace for carburizing and sintering, directly heating to a sintering temperature for heat preservation during carburizing and sintering, wherein the sintering temperature is 1370-1410 ℃, the heat preservation time is 30-90 min, and cooling to room temperature along with the furnace after heat preservation is finished;
(3) and after the carburization and sintering are finished, taking out the hard alloy product from the graphite particles of the graphite boat, recycling the graphite particles, and performing sand blasting treatment on the hard alloy product to obtain the carburized hard alloy.
Preferably, in the step (1), the graphite particles have a particle size of phi 0.5-3.0 mm, and the graphite particles are 100% by mass of metallurgical grade graphite particles. The carburizing agent adopts graphite particles and has two functions: firstly, the loose packing density of graphite particles is high, and the graphite particles are not easy to diffuse into the hearth or even into a vacuum pipeline in the carburizing and sintering process, so that the pipeline of a sintering furnace is not damaged, and the graphite particles can not diffuse into the air to pollute the environment; and secondly, the graphite particles are easy to separate from the hard alloy decarburization product and are not easy to adhere to the surface of the hard alloy, so that the separation time can be saved, and the production efficiency can be improved.
Preferably, in the step (2), when the dewaxing and sintering integrated furnace is used, the sintering process atmosphere is as follows: the vacuum atmosphere is arranged before the sintering temperature, argon is filled after the sintering temperature is reached, and the absolute pressure of the argon in the dewaxing and sintering integrated furnace is kept at 50 +/-10 mbar.
Preferably, in the step (2), when a pressure sintering furnace is adopted, the sintering process atmosphere is as follows: and (3) before the sintering temperature, a vacuum atmosphere is adopted, argon is filled after the sintering temperature is reached, and the absolute pressure of the argon in the pressure sintering furnace is kept at 10-60 bar.
The beneficial technical effects of the invention are as follows:
the invention provides a hard alloy carburizing method, which adopts a dewaxing and sintering integrated furnace or a pressure sintering furnace to replace a molybdenum wire hydrogen sintering furnace for carburizing and sintering, adopts larger graphite particles (phi 0.5-3.0 mm), and is not easy to diffuse into a hearth or even a vacuum pipeline in the carburizing and sintering process due to the larger density of the graphite particles, so that the pipeline of the sintering furnace cannot be damaged, and the graphite particles cannot diffuse into the air to pollute the environment; and the graphite particles are easy to separate from the hard alloy decarburization product and are not easy to adhere to the surface of the hard alloy, so that the separation time can be saved, and the production efficiency can be improved.
The invention provides a carburizing method of hard alloy, which adopts a graphite cover plate to seal a graphite boat, further prevents graphite particles from diffusing into the hearth and even into a vacuum pipeline, and the graphite cover plate plays a key role in controlling the carbon atmosphere in the carburizing process, effectively performs carburizing treatment on hard alloy decarburization products, and leads the carbon atmosphere to reach certain concentration by introducing argon into a dewaxing sintering integrated furnace or a pressure sintering furnace and controlling certain pressure, thereby realizing the elimination of hard alloy decarburization defects, short process and low production cost.
Drawings
FIG. 1 is a process flow diagram of the cemented carbide carburizing process of the present invention.
FIG. 2 is a phase diagram of decarburized cemented carbide alloy selected in example 1.
FIG. 3 is a diagram of the gold phase of cemented carbide treated by the method of example 1.
FIG. 4 is a decarburized metallographic image of a cemented carbide selected in example 2.
FIG. 5 is a diagram of the gold phase of cemented carbide after treatment in example 2.
FIG. 6 is a decarburized metallographic image of a cemented carbide selected in example 3.
FIG. 7 is a diagram of the gold phase of cemented carbide treated by the method of example 3.
FIG. 8 is a phase diagram of cemented carbide gold after treatment by the method of comparative example 1.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by those skilled in the art without any creative work based on the embodiments of the present invention belong to the protection scope of the present invention.
The principle of the invention is as follows: the hard alloy decarburization product is buried in metallurgical-grade graphite particles, and in the sealed environment of a graphite boat and a graphite cover plate, under the sintering temperature, the graphite product generates a carbon atmosphere in the sealed space of the boat, the carbon atmosphere can be continuously reserved in the boat under the inert gas pressure in the furnace, and the carbon atmosphere in the boat continuously permeates into the hard alloy decarburization product, so that the carburizing effect is achieved; the graphite boat which adopts larger graphite particles (phi 0.5-3.0 mm) and is sealed can prevent the graphite particles from being pumped away when the sintering furnace is vacuumized; according to the different brands, models and decarburization degree of the products, the sintering temperature, the heat preservation time and the atmosphere pressure can be adjusted.
The invention will be further illustrated with reference to the following specific examples and the accompanying drawings:
example 1
Hard alloy decarburization product, parameters: 196kg of long strips of sheets with the mark YG8.2, the size of 320mm multiplied by 12mm multiplied by 4mm and the metallographic microstructure of decarburized eta phase (E50), and the metallographic picture of the hard alloy is shown in figure 2.
The invention provides a carburizing method of hard alloy, which comprises the following steps:
(1) placing each hard alloy decarburization product in a square graphite boat, burying the products with graphite particles (phi 0.5-3.0 mm), and sealing and covering the products with a graphite cover plate to form a sealed graphite boat space;
(2) putting the sealed graphite boat into a dewaxing and sintering integrated furnace, directly heating to a sintering temperature of 1410 ℃ under a vacuum atmosphere, introducing argon, keeping the pressure of the argon at 50 +/-10 mbar for 30min, and cooling to room temperature along with the furnace after the heat preservation is finished;
(3) and after the carburization and sintering are finished, taking out the hard alloy product from the graphite particles of the graphite boat, recycling the graphite particles, and performing sand blasting treatment on the hard alloy product to obtain the carburized hard alloy.
2 products after sand blasting treatment are randomly extracted for metallographic detection and analysis, the metallographic microstructure of the analysis result has no decarburization eta phase, the metallographic microstructure C types are all C00, and the specific metallographic diagram is shown in figure 3.
Example 2
Hard alloy decarburization product, parameters: the alloy phase diagram of the hard alloy is shown in figure 4, wherein 24 cylindrical bodies are provided with the mark YG8, the size phi is 30mm multiplied by 20mm, and the metallographic microstructure is provided with decarburization eta phase (E14).
The invention provides a carburizing method of hard alloy, which comprises the following steps:
(1) placing each hard alloy decarburization product in a round graphite boat, burying the products with graphite particles (phi 0.5-3.0 mm), and sealing and covering the products with a graphite cover plate to form a sealed graphite boat space;
(2) putting the sealed graphite boat into a dewaxing and sintering integrated furnace, carrying other hard alloy products, heating to a sintering temperature of 1390 ℃, introducing argon gas at the moment, keeping the pressure of the argon gas at 50 +/-10 mbar, keeping the temperature for 60min, and cooling to room temperature along with the furnace after the heat preservation is finished;
(3) and after the carburization and sintering are finished, taking out the hard alloy product from the graphite particles of the graphite boat, recycling the graphite particles, and performing sand blasting treatment on the hard alloy product to obtain the carburized hard alloy.
2 products after sand blasting treatment are randomly extracted for metallographic detection and analysis, the metallographic microstructure of the analysis result has no decarburization eta phase, the metallographic microstructure C types are all C00, and the specific metallographic diagram is shown in figure 5.
Example 3
Hard alloy decarburization product, parameters: size YG8.2
30 pieces of products with a metallurgical microstructure of decarburization eta phase (E06), and a metallographic picture of the cemented carbide is shown in FIG. 6.
The invention provides a carburizing method of hard alloy, which comprises the following steps:
(1) placing each hard alloy decarburization product in a square graphite boat, burying the products with graphite particles (phi 0.5-3.0 mm), and sealing and covering the products with a graphite cover plate to form a sealed graphite boat space;
(2) putting the sealed graphite boat into a pressure sintering furnace, directly heating to a sintering temperature of 1370 ℃ under a vacuum atmosphere, then filling argon, keeping the pressure of the argon at 50bar, performing pressure sintering, keeping the temperature for 90min, and cooling to room temperature along with the furnace after the temperature is kept;
(3) and after the carburization and sintering are finished, taking out the hard alloy product from the graphite particles of the graphite boat, recycling the graphite particles, and performing sand blasting treatment on the hard alloy product to obtain the carburized hard alloy.
2 products after sand blasting treatment are randomly extracted for metallographic detection and analysis, the metallographic microstructure of the analysis result has no decarburization eta phase, the metallographic microstructure C types are all C00, and the specific metallographic diagram is shown in figure 7.
Comparative example 1
Using 30 pieces of the cemented carbide decarburized article of example 3, carburization was performed, including:
(1) placing each hard alloy decarburization product in a square graphite boat, burying the products with graphite powder, and sealing and covering the products with a graphite cover plate to form a sealed graphite boat space;
(2) putting the sealed graphite boat into a vacuum sintering furnace, directly heating to the sintering temperature of 1450 ℃ under the vacuum atmosphere, keeping the temperature for 120min, and cooling to room temperature along with the furnace after the temperature is kept;
(3) and after the carburization and sintering are finished, taking out the hard alloy decarbonized product from the graphite particles of the graphite boat, recycling the graphite particles, and performing sand blasting treatment on the hard alloy decarbonized product to obtain the carburized hard alloy.
2 products after sand blasting treatment are randomly extracted for metallographic detection and analysis, the metallographic microstructure still has decarburization eta phase as a result of analysis, the E types of the metallographic microstructure are all E06, and a specific metallographic diagram is shown in FIG. 8.
Claims (2)
1. A carburizing method for cemented carbide, characterized by comprising the steps of:
(1) uniformly laying graphite particles in a graphite boat, filling the hard alloy decarburization product into the graphite particles, and sealing the graphite boat by using a graphite cover plate to obtain an assembled hard alloy and graphite assembly;
(2) putting the assembled hard alloy and graphite assembly obtained in the step (1) into a dewaxing and sintering integrated furnace or a pressure sintering furnace for carburizing and sintering, directly heating to a sintering temperature for heat preservation during carburizing and sintering, wherein the sintering temperature is 1370-1410 ℃, the heat preservation time is 30-90 min, and cooling to room temperature along with the furnace after heat preservation is finished;
(3) after the carburization and sintering are finished, taking out the hard alloy product from the graphite particles of the graphite boat, recycling the graphite particles, and performing sand blasting treatment on the hard alloy product to obtain carburized hard alloy;
in the step (2), when a dewaxing and sintering integrated furnace is adopted, the sintering process atmosphere is as follows: before the sintering temperature, a vacuum atmosphere is adopted, argon is filled after the sintering temperature is reached, and the absolute pressure of the argon in the dewaxing and sintering integrated furnace is kept at 50 +/-10 mbar;
in the step (2), when a pressure sintering furnace is adopted, the sintering process atmosphere is as follows: and (3) before the sintering temperature, a vacuum atmosphere is adopted, argon is filled after the sintering temperature is reached, and the absolute pressure of the argon in the pressure sintering furnace is kept at 10-60 bar.
2. The method for carburizing the hard alloy according to claim 1, wherein in the step (1), the graphite particles have a particle size of 0.5 to 3.0mm, and the graphite particles are 100% by mass of metallurgical grade graphite particles.
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| JP5570101B2 (en) * | 2008-06-17 | 2014-08-13 | 日新製鋼株式会社 | Method for producing spheroidized carburized steel sheet and annealed steel strip |
| CN105331868A (en) * | 2015-11-10 | 2016-02-17 | 中南大学 | Preparation method of WC-Co hard alloy of gradient structure |
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| CN100441730C (en) * | 2003-09-24 | 2008-12-10 | 自贡硬质合金有限责任公司 | Hard alloy carburizing process resulting in gradient distribution of mechanical performance |
| CN104493161B (en) * | 2015-01-19 | 2017-01-18 | 四川科力特硬质合金股份有限公司 | Carburization method for hard alloy in vacuum sintering furnace |
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| JP5570101B2 (en) * | 2008-06-17 | 2014-08-13 | 日新製鋼株式会社 | Method for producing spheroidized carburized steel sheet and annealed steel strip |
| CN105331868A (en) * | 2015-11-10 | 2016-02-17 | 中南大学 | Preparation method of WC-Co hard alloy of gradient structure |
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