CN111607715A - Tungsten-cobalt hard alloy sintering process - Google Patents
Tungsten-cobalt hard alloy sintering process Download PDFInfo
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- CN111607715A CN111607715A CN202010462209.5A CN202010462209A CN111607715A CN 111607715 A CN111607715 A CN 111607715A CN 202010462209 A CN202010462209 A CN 202010462209A CN 111607715 A CN111607715 A CN 111607715A
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/045—Alloys based on refractory metals
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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
- B22F3/10—Sintering only
- B22F3/1017—Multiple heating or additional steps
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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
- B22F3/10—Sintering only
- B22F3/1017—Multiple heating or additional steps
- B22F3/1028—Controlled cooling
Abstract
The invention relates to a tungsten-cobalt hard alloy sintering process, which comprises the following steps: after the sintering heat preservation is finished, sequentially carrying out first furnace cooling, air cooling and second furnace cooling; the sintering at least comprises one section of sintering. According to the invention, through reasonable configuration of the cooling process after the sintering of the tungsten-cobalt alloy is finished, the effective retention of alpha-Co in the hard alloy is realized, and simultaneously, the bending strength and the impact toughness of the hard alloy are also improved.
Description
Technical Field
The invention relates to the field of hard alloy sintering, in particular to a tungsten-cobalt hard alloy sintering process.
Background
The tungsten-cobalt hard alloy is hard alloy consisting of tungsten carbide and metal cobalt. As the cobalt content and WC grain size increase, the hardness of the alloy decreases and the bending strength and impact resistance increase. The W-Co hard alloy may be used in cutting cast iron, non-ferrous metal and non-metal material, and may be also used as antiwear tool for drawing die, cold punching die, nozzle, roller, anvil, measuring tool, cutting tool, etc. and mine tool.
In the production of cemented carbide, the key factor determining the quality of the product is the molecular structure of the alloy. In the high-temperature sintering stage, alpha-Co is taken as the main component in the gamma phase of the solid solution phase, and the crystal lattice of the gamma phase is an fcc face-centered cubic structure which has good toughness and can absorb more strain energy and relaxation stress under the action of external force. When the material is slowly cooled after sintering is finished, the alpha-Co is converted to the-Co, the-Co is in a stable state at normal temperature, the crystal lattice of the material is an hcp close-packed hexagonal structure, and the structure has poor capability of absorbing strain energy and relaxing stress and poor toughness. CN110578067A discloses a sintering method of ultra-fine cemented carbide, comprising the following steps: mixing WC powder, Co powder, an inhibitor and a forming agent, wet-grinding, drying after wet grinding, and pressing into a pressed blank; heating the pressed compact to a sintering temperature under the atmosphere of H2, and then carrying out heat preservation sintering under the atmosphere of argon; after sintering, cooling to a first-stage temperature at a first-stage cooling rate under the conditions of electrification and pressure maintaining, and preserving heat; then, cooling to a second-stage temperature at a second-stage cooling speed, and preserving heat; then, cooling to a third-stage temperature at a third-stage cooling rate; then cutting off the power and quickly cooling to below 50 ℃ to obtain the hard alloy. The method of the invention properly reduces the sintering temperature, adopts the step-by-step slow cooling process under electrification and pressure after heat preservation and pressure maintaining, can reduce the abnormal growth probability of the ultrafine hard alloy crystal grains, improves the uniformity of the microstructure, and improves the fracture toughness and the use stability of the alloy. CN109957671A discloses a hard alloy sintering process, which comprises the following sintering processes at high temperature stage: step 1, sintering at 1340-1500 ℃, pressurizing at 1-10 MPa for 5-15 minutes, and then releasing the pressure to less than or equal to 1 MPa; and 2, repeating the operations of pressurizing, pressure maintaining and pressure relief in the step 1 for 1-3 times, and finally cooling and relieving the pressure to normal temperature and normal pressure to obtain the hard alloy. The hard alloy sintering process provided by the invention can be used for selecting, grinding and pressing raw materials according to the requirement by adopting the prior art, and in the high-temperature and high-pressure sintering process, the density of the prepared hard alloy is improved by repeated pressurization, pressure maintaining and pressure relief operations under the heat preservation condition, so that a hard alloy product with excellent hardness, fracture toughness, bending strength and other properties, compact tissue, uniform grain size and complete grain development is obtained.
However, at present, in order to keep more α -Co to the normal temperature state, a water rapid cooling system is basically adopted, but the effect is not particularly good, and the cooling speed is faster than the furnace cooling, but is unstable.
Disclosure of Invention
In view of the problems in the prior art, the invention aims to provide a sintering process for a tungsten-cobalt hard alloy, which can effectively retain alpha-Co in the hard alloy and improve the bending strength and impact toughness of the hard alloy.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a tungsten-cobalt hard alloy sintering process, which comprises the following steps: after the sintering heat preservation is finished, sequentially carrying out first furnace cooling, air cooling and second furnace cooling; the sintering at least comprises one section of sintering.
According to the invention, through reasonable configuration of the cooling process after the sintering of the tungsten-cobalt alloy is finished, the effective retention of alpha-Co in the hard alloy is realized, and simultaneously, the bending strength and the impact toughness of the hard alloy are also improved.
In the present invention, the tungsten-cobalt cemented carbide may be YG8, YG13, YG11, YG18c, or the like.
As a preferable embodiment of the present invention, the sintering includes a first sintering, a second sintering, a third sintering, a fourth sintering, a fifth sintering, a sixth sintering, and a seventh sintering, which are performed in this order.
In the invention, through multi-stage sintering, the performance of the product is improved by reasonably utilizing the action of each temperature and the synergistic effect among the multi-stage sintering.
In a preferred embodiment of the present invention, the end point temperature of the first sintering temperature rise is 190-210 ℃, and may be, for example, 190 ℃, 195 ℃, 200 ℃, 205 ℃, or 210 ℃, but is not limited to the above-mentioned values, and other values not shown in the above range are also applicable.
Preferably, the temperature rise time of the first sintering is 50 to 70min, for example, 50min, 52min, 54min, 56min, 58min, 60min, 62min, 64min, 66min, 68min or 70min, etc., but not limited to the recited values, and other values not recited in the range are also applicable.
Preferably, the first sintering is performed for 50-70min, such as 50min, 52min, 54min, 56min, 58min, 60min, 62min, 64min, 66min, 68min or 70min, but not limited to the values listed, and other values not listed in the range are also applicable.
Preferably, the end point temperature of the second sintering temperature rise is 310-330 ℃, such as 310 ℃, 315 ℃, 320 ℃, 325 ℃, or 330 ℃, but not limited to the recited values, and other values not recited in the range are also applicable.
Preferably, the temperature rise time of the second sintering is 75 to 90min, for example, 75min, 80min, 85min or 90min, but not limited to the values listed, and other values not listed in the range are also applicable.
Preferably, the holding time for the second sintering is 85-95min, such as 85min, 86min, 87min, 88min, 89min, 90min, 91min, 92min, 93min, 94min or 95min, but not limited to the values listed, and other values not listed in this range are also applicable.
In a preferred embodiment of the present invention, the temperature at the end point of the third sintering temperature rise is 390-410 ℃, and may be, for example, 390 ℃, 392 ℃, 394 ℃, 396 ℃, 398 ℃, 400 ℃, 402 ℃, 404 ℃, 406 ℃, 408 ℃ or 410 ℃, but is not limited to the above-mentioned values, and other values not listed in this range are also applicable.
Preferably, the temperature rise time of the third sintering is 85 to 95min, for example, 85min, 86min, 87min, 88min, 89min, 90min, 91min, 92min, 93min, 94min or 95min, etc., but not limited to the values listed, and other values not listed in the range are also applicable.
Preferably, the heat preservation time of the third sintering is 85-95min, such as 85min, 86min, 87min, 88min, 89min, 90min, 91min, 92min, 93min, 94min or 95min, but not limited to the enumerated values, and other unrecited values in the range are also applicable.
Preferably, the end point temperature of the fourth sintering temperature rise is 580-620 ℃, for example 580 ℃, 585 ℃, 590 ℃, 595 ℃, 600 ℃, 605 ℃, 610 ℃, 615 ℃ or 620 ℃, but not limited to the recited values, and other values not recited in the range are also applicable.
Preferably, the temperature rise time of the fourth sintering is 95 to 105min, for example, 95min, 96min, 97min, 98min, 99min, 100min, 101min, 102min, 103min, 104min or 105min, etc., but not limited to the recited values, and other values not recited in the range are also applicable.
Preferably, the heat preservation time of the fourth sintering is 55-65min, such as 55min, 56min, 57min, 58min, 59min, 60min, 61min, 62min, 63min, 64min or 65min, but not limited to the values listed, and other values not listed in the range are also applicable.
In a preferred embodiment of the present invention, the end point temperature of the fifth sintering temperature rise is 780-820 ℃, for example 780 ℃, 785 ℃, 790 ℃, 795 ℃, 800 ℃, 805 ℃, 810 ℃, 815 ℃ or 820 ℃, but is not limited to the above-mentioned values, and other values not shown in the above range are also applicable.
Preferably, the temperature rise time of the fifth sintering is 55-65min, for example, 55min, 56min, 57min, 58min, 59min, 60min, 61min, 62min, 63min, 64min or 65min, but not limited to the values listed, and other values not listed in the range are also applicable.
Preferably, the heat preservation time of the fifth sintering is 25-35min, such as 25min, 26min, 27min, 28min, 29min, 30min, 31min, 32min, 33min, 34min or 35min, but not limited to the enumerated values, and other unrecited values in the range are also applicable.
In a preferred embodiment of the present invention, the temperature at the end of the sixth sintering temperature rise is 1230-.
Preferably, the temperature rise time of the sixth sintering is 110-130min, such as 110min, 112min, 114min, 116min, 118min, 120min, 122min, 124min, 126min, 128min or 130min, but not limited to the values listed, and other values not listed in the range are also applicable.
Preferably, the holding time for the sixth sintering is 55-65min, such as 55min, 56min, 57min, 58min, 59min, 60min, 61min, 62min, 63min, 64min or 65min, but not limited to the values listed, and other values not listed in the range are also applicable.
In a preferred embodiment of the present invention, the terminal temperature of the seventh sintering temperature rise is 1420-.
Preferably, the temperature rise time of the seventh sintering is 85 to 95min, for example, 85min, 86min, 87min, 88min, 89min, 90min, 91min, 92min, 93min, 94min or 95min, etc., but not limited to the values listed, and other values not listed in the range are also applicable.
Preferably, the heat preservation time of the seventh sintering is 70 to 80min, for example, 70min, 71min, 72min, 73min, 74min, 75min, 76min, 77min, 78min, 79min or 80min, etc., but not limited to the recited values, and other values not recited in the range are also applicable.
As a preferred embodiment of the present invention, the end point temperature of the first furnace cooling is 730-770 deg.C, such as 730 deg.C, 735 deg.C, 740 deg.C, 745 deg.C, 750 deg.C, 755 deg.C, 760 deg.C, 765 deg.C or 770 deg.C, but not limited to the values listed, and other values not listed in this range are also applicable.
Preferably, the first furnace cooling time is 380-420min, such as 380min, 385min, 390min, 395min, 400min, 405min, 410min, 415min, or 420min, but not limited to the values listed, and other values not listed in the range are also applicable.
In a preferred embodiment of the present invention, the end point temperature of the air cooling is 380-420 ℃, and may be 380 ℃, 385 ℃, 390 ℃, 395 ℃, 400 ℃, 405 ℃, 410 ℃, 415 ℃ or 420 ℃, for example, but not limited to the values listed, and other values not listed in the range are also applicable.
Preferably, the air cooling time is 25-35min, such as 25min, 26min, 27min, 28min, 29min, 30min, 31min, 32min, 33min, 34min or 35min, but not limited to the recited values, and other values not recited in the range are also applicable.
Preferably, the air cooling is performed under a protective atmosphere.
Preferably, the protective atmosphere comprises nitrogen and/or an inert gas.
In the present invention, the inert gas may be 1 or a combination of at least 2 of helium, neon, argon, or the like.
Preferably, the purity of the gas in the protective atmosphere is 99.99% or more, and may be, for example, 99.99%, 99.991%, 99.992%, 99.993%, 99.994%, 99.995%, 99.996%, 99.997%, 99.998%, or 99.999%, etc., but is not limited to the recited values, and other values not recited in this range are also applicable.
Preferably, the end point temperature of the second furnace cooling is 80-100 ℃, for example 80 ℃, 82 ℃, 84 ℃, 86 ℃, 88 ℃, 90 ℃, 92 ℃, 94 ℃, 96 ℃, 98 ℃ or 100 ℃, but not limited to the recited values, and other values not recited in this range are also applicable.
The gas cooling process in the process adopts a mode of adding protective gas between 730-770 ℃, so that the alloy product can be reduced to about 400 ℃ within half an hour, and then is cooled along with the furnace, and the conversion temperature can be basically avoided.
As a preferable technical scheme of the invention, the process comprises the following steps: after the sintering heat preservation is finished, sequentially carrying out first furnace cooling, air cooling and second furnace cooling; the sintering at least comprises a section of sintering;
the sintering comprises a first sintering, a second sintering, a third sintering, a fourth sintering, a fifth sintering, a sixth sintering and a seventh sintering which are sequentially carried out; the end temperature of the first sintering temperature rise is 190-210 ℃; the temperature rise time of the first sintering is 50-70 min; the heat preservation time of the first sintering is 50-70 min; the end temperature of the second sintering temperature rise is 310-330 ℃; the temperature rise time of the second sintering is 75-90 min; the heat preservation time of the second sintering is 85-95 min; the end temperature of the third sintering temperature rise is 390-410 ℃; the temperature rise time of the third sintering is 85-95 min; the heat preservation time of the third sintering is 85-95 min; the end temperature of the fourth sintering temperature rise is 580-620 ℃; the temperature rise time of the fourth sintering is 95-105 min; the heat preservation time of the fourth sintering is 55-65 min; the terminal temperature of the fifth sintering temperature rise is 780-820 ℃; the temperature rise time of the fifth sintering is 55-65 min; the heat preservation time of the fifth sintering is 25-35 min; the end temperature of the sixth sintering temperature rise is 1230-; the temperature rise time of the sixth sintering is 110-130 min; the heat preservation time of the sixth sintering is 55-65 min; the terminal temperature of the seventh sintering temperature rise is 1420-1450 ℃; the temperature rise time of the seventh sintering is 85-95 ℃; the heat preservation time of the seventh sintering is 70-80 min; the end temperature of the first furnace cooling is 730-770 ℃; the time for cooling the first furnace is 380-420 min; the air cooling end temperature is 380-420 ℃; the air cooling time is 25-35 min; and the end temperature of the second furnace cooling is 80-100 ℃.
Compared with the prior art, the invention has the following beneficial effects:
(1) according to the invention, through reasonable configuration of sectional sintering and sectional cooling of the tungsten-cobalt alloy, effective retention of alpha-Co in the hard alloy is realized, and simultaneously, the bending strength and the impact toughness of the hard alloy are also improved. The bending strength of the obtained hard alloy can reach more than 2150MPa, the volume ratio of alpha-Co at normal temperature reaches more than 65%, and the effective service time of the alloy product sintered by the process is prolonged by 20-40% through destructive tests.
(2) The sintering process not only improves the use efficiency of equipment, but also saves the equipment cost. Meanwhile, the service performance of the hard alloy is greatly improved.
The present invention is described in further detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.
Detailed Description
To better illustrate the invention and to facilitate the understanding of the technical solutions thereof, typical but non-limiting examples of the invention are as follows:
example 1
The hard alloy in this embodiment is a YG8 stamping die.
The embodiment provides a tungsten-cobalt hard alloy sintering process, which comprises the following steps: after the sintering heat preservation is finished, sequentially carrying out first furnace cooling, air cooling and second furnace cooling; the sintering at least comprises a section of sintering;
the sintering comprises a first sintering, a second sintering, a third sintering, a fourth sintering, a fifth sintering, a sixth sintering and a seventh sintering which are sequentially carried out; the end point temperature of the first sintering temperature rise is 200 ℃; the temperature rise time of the first sintering is 60 min; the heat preservation time of the first sintering is 70 min; the end point temperature of the second sintering temperature rise is 310 ℃; the temperature rise time of the second sintering is 80 min; the heat preservation time of the second sintering is 85 min; the end point temperature of the third sintering temperature rise is 405 ℃; the temperature rise time of the third sintering is 95 min; the heat preservation time of the third sintering is 90 min; the end point temperature of the fourth sintering temperature rise is 610 ℃; the temperature rise time of the fourth sintering is 100 min; the heat preservation time of the fourth sintering is 60 min; the end point temperature of the fifth sintering temperature rise is 810 ℃; the temperature rise time of the fifth sintering is 60 min; the heat preservation time of the fifth sintering is 30 min; the terminal temperature of the sixth sintering temperature rise is 1250 ℃; the heating time of the sixth sintering is 125 min; the heat preservation time of the sixth sintering is 60 min; the end point temperature of the seventh sintering temperature rise is 1445 ℃; the temperature rise time of the seventh sintering is 86 ℃; the heat preservation time of the seventh sintering is 76 min; the end temperature of the first furnace cooling is 850 ℃; the time of the first furnace cooling is 400 min; the end temperature of the air cooling is 400 ℃; the air cooling time is 30 min; the end temperature of the second furnace cooling is 95 ℃.
The bending strength of the obtained hard alloy is 2150MPa, the volume percentage of alpha-Co at normal temperature is 67%, and the effective service time of an alloy product sintered by the process is prolonged by 26% through destructive tests.
Example 2
The cemented carbide in this example was a YG18C ball die.
The embodiment provides a tungsten-cobalt hard alloy sintering process, which comprises the following steps: after the sintering heat preservation is finished, sequentially carrying out first furnace cooling, air cooling and second furnace cooling; the sintering at least comprises a section of sintering;
the sintering comprises a first sintering, a second sintering, a third sintering, a fourth sintering, a fifth sintering, a sixth sintering and a seventh sintering which are sequentially carried out; the end point temperature of the first sintering temperature rise is 190 ℃; the temperature rise time of the first sintering is 70 min; the heat preservation time of the first sintering is 50 min; the end point temperature of the second sintering temperature rise is 310 ℃; the temperature rise time of the second sintering is 85 min; the heat preservation time of the second sintering is 85 min; the final temperature of the third sintering temperature rise is 395 ℃; the temperature rise time of the third sintering is 90 min; the heat preservation time of the third sintering is 90 min; the end point temperature of the fourth sintering temperature rise is 585 ℃; the temperature rise time of the fourth sintering is 105 min; the heat preservation time of the fourth sintering is 62 min; the end point temperature of the fifth sintering temperature rise is 810 ℃; the temperature rise time of the fifth sintering is 55 min; the heat preservation time of the fifth sintering is 28 min; the final temperature of the sixth sintering temperature rise is 1235 ℃; the heating time of the sixth sintering is 120 min; the heat preservation time of the sixth sintering is 57 min; the terminal temperature of the seventh sintering temperature rise is 1450 ℃; the temperature rise time of the seventh sintering is 86 ℃; the heat preservation time of the seventh sintering is 80 min; the end temperature of the first furnace cooling is 745 ℃; the time for cooling the first furnace is 390 min; the end temperature of the air cooling is 410 ℃; the air cooling time is 27 min; the end temperature of the second furnace cooling was 97 ℃.
The bending strength of the obtained hard alloy is 2930MPa, the volume percentage of alpha-Co at normal temperature is 72%, and the effective service time of an alloy product sintered by the process is prolonged by 35% through destructive tests.
Example 3
The cemented carbide in this example was YG6 button.
The embodiment provides a tungsten-cobalt hard alloy sintering process, which comprises the following steps: after the sintering heat preservation is finished, sequentially carrying out first furnace cooling, air cooling and second furnace cooling; the sintering at least comprises a section of sintering;
the sintering comprises a first sintering, a second sintering, a third sintering, a fourth sintering, a fifth sintering, a sixth sintering and a seventh sintering which are sequentially carried out; the end point temperature of the first sintering temperature rise is 210 ℃; the temperature rise time of the first sintering is 50 min; the heat preservation time of the first sintering is 52 min; the end point temperature of the second sintering temperature rise is 315 ℃; the temperature rise time of the second sintering is 80 min; the heat preservation time of the second sintering is 87 min; the end point temperature of the third sintering temperature rise is 390 ℃; the temperature rise time of the third sintering is 85 min; the heat preservation time of the third sintering is 90 min; the end point temperature of the fourth sintering temperature rise is 587 ℃; the temperature rise time of the fourth sintering is 96 min; the heat preservation time of the fourth sintering is 63 min; the end point temperature of the fifth sintering temperature rise is 795 ℃; the temperature rise time of the fifth sintering is 57 min; the heat preservation time of the fifth sintering is 28 min; the terminal temperature of the sixth sintering temperature rise is 1250 ℃; the heating time of the sixth sintering is 115 min; the heat preservation time of the sixth sintering is 63 min; the end point temperature of the seventh sintering temperature rise is 1420 ℃; the temperature rise time of the seventh sintering is 90 ℃; the heat preservation time of the seventh sintering is 72 min; the end temperature of the first furnace cooling is 745 ℃; the time for cooling the first furnace is 390 min; the air cooling end temperature is 383 ℃; the air cooling time is 27 min; the end temperature of the second furnace cooling is 85 ℃.
The bending strength of the obtained hard alloy is 2460MPa, the volume percentage of alpha-Co at normal temperature is 65%, and the effective service time of an alloy product sintered by the process is prolonged by 23% through destructive tests.
Example 4
The cemented carbide in this example was YG11 serrations.
The embodiment provides a tungsten-cobalt hard alloy sintering process, which comprises the following steps: after the sintering heat preservation is finished, sequentially carrying out first furnace cooling, air cooling and second furnace cooling; the sintering at least comprises a section of sintering;
the sintering comprises a first sintering, a second sintering, a third sintering, a fourth sintering, a fifth sintering, a sixth sintering and a seventh sintering which are sequentially carried out; the end point temperature of the first sintering temperature rise is 197 ℃; the temperature rise time of the first sintering is 58 min; the heat preservation time of the first sintering is 62 min; the end point temperature of the second sintering temperature rise is 319 ℃; the temperature rise time of the second sintering is 87 min; the heat preservation time of the second sintering is 94 min; the final temperature of the third sintering temperature rise is 397 ℃; the temperature rise time of the third sintering is 87 min; the heat preservation time of the third sintering is 88 min; the end point temperature of the fourth sintering temperature rise is 597 ℃; the temperature rise time of the fourth sintering is 101 min; the heat preservation time of the fourth sintering is 58 min; the end point temperature of the fifth sintering temperature rise is 807 ℃; the temperature rise time of the fifth sintering is 62 min; the heat preservation time of the fifth sintering is 33 min; the end point temperature of the sixth sintering temperature rise is 1254 ℃; the heating time of the sixth sintering is 117 min; the heat preservation time of the sixth sintering is 61 min; the terminal temperature of the seventh sintering temperature rise is 1438 ℃; the temperature rise time of the seventh sintering is 88 ℃; the heat preservation time of the seventh sintering is 74 min; the end point temperature of the first furnace cooling is 747 ℃; the time of the first furnace cooling is 407 min; the air cooling end temperature is 398 ℃; the air cooling time is 32 min; the end temperature of the second furnace cooling is 92 ℃.
The bending strength of the obtained hard alloy is 2790MPa, the volume percentage of alpha-Co at normal temperature is 69%, and the effective service time of the alloy product sintered by the process is prolonged by 24% through destructive tests.
Comparative example 1
Only the difference from the example 1 is that the temperature is directly raised to the end point temperature of the second sintering without the first sintering and the heat preservation is started; the bending strength of the obtained hard alloy is 1420MPa, the volume percentage of alpha-Co at normal temperature is 65%, and the effective service time of an alloy product sintered by the process is shortened by 50% through destructive tests.
Comparative example 2
Only the difference from the example 1 is that the temperature is directly raised to the end point temperature of the third sintering without the second sintering and the heat preservation is started; the bending strength of the obtained hard alloy is 1380MPa, the volume percentage of alpha-Co at normal temperature is 63%, and the effective service time of an alloy product sintered by the process is shortened by 45% through destructive tests.
Comparative example 3
Only the difference from the example 1 is that the temperature is directly raised to the end point temperature of the fourth sintering without performing the third sintering and the heat preservation is started; the bending strength of the obtained hard alloy is 1650MPa, the volume percentage of the alpha-Co at normal temperature is 68%, and the effective service time of the alloy product sintered by the process is not prolonged through destructive tests.
Comparative example 4
Only the difference from the example 1 is that the fourth sintering is not carried out, the temperature is directly increased to the end point temperature of the fifth sintering, and the heat preservation is started; the bending strength of the obtained hard alloy is 1670MPa, the volume percentage of alpha-Co at normal temperature is 65%, and the effective service time of an alloy product sintered by the process is not prolonged through destructive tests.
Comparative example 5
Only the difference from the example 1 is that the fourth sintering is not carried out, the temperature is directly increased to the end point temperature of the fifth sintering, and the heat preservation is started; the bending strength of the obtained hard alloy is 1660MPa, the volume percentage of alpha-Co at normal temperature is 67%, and the effective service time of the alloy product sintered by the process is not prolonged through destructive tests.
Comparative example 6
Only the difference from the example 1 is that the fifth sintering is not carried out, the temperature is directly increased to the end point temperature of the seventh sintering, and the heat preservation is started; the bending strength of the obtained hard alloy is 1940MPa, the volume percentage of alpha-Co at normal temperature is 64%, and the effective service time of an alloy product sintered by the process is prolonged by 5% through destructive tests.
Comparative example 11
The only difference from embodiment 1 is that the first furnace cooling, the air cooling and the second furnace cooling are replaced with the liquid cooling of the same cooling condition; the bending strength of the obtained hard alloy is 1890MPa, the volume percentage of alpha-Co at normal temperature is 15%, and the effective service time of an alloy product sintered by the process is prolonged by 10% through destructive tests.
Comparative example 12
Only the difference from example 1 is that the air cooling is replaced by furnace cooling of the same cooling conditions; the bending strength of the obtained hard alloy is 1860MPa, the volume percentage of alpha-Co at normal temperature is 5%, and the effective service time of an alloy product sintered by the process is not prolonged through destructive tests.
Comparative example 14
The difference from the example 1 is only that the starting temperature of air cooling (the end temperature of first furnace cooling) is 700 ℃, the bending strength of the obtained hard alloy is 2080MPa, the volume ratio of alpha-Co at normal temperature is 56%, and the effective service time of the alloy product sintered by the process is prolonged by 19% through destructive tests.
Comparative example 15
The difference from example 1 is only that the final temperature of the air cooling is 500 ℃, the bending strength of the obtained hard alloy is 1890MPa, the volume ratio of alpha-Co at normal temperature is 43%, and the effective service time of the alloy product sintered by the process is prolonged by 8% through destructive test.
Comparative example 16
The difference from example 1 is only that the final temperature of the air cooling is 300 ℃, the bending strength of the obtained hard alloy is 1880MPa, the volume ratio of alpha-Co at normal temperature is 20%, and the effective service time of the alloy product sintered by the process is prolonged by 1% through destructive test.
The bending strength, the volume ratio of alpha-Co at normal temperature and the destructive test of the hard alloy in the above examples and comparative examples of the present invention were tested by using GB3851-1983, X-ray diffraction and Joule continuous Impactor in this order.
According to the results of the above examples and comparative examples, in the present invention, the reasonable configuration of the sectional sintering and the sectional cooling of the tungsten-cobalt alloy realizes the effective retention of α -Co in the cemented carbide, and simultaneously improves the bending strength and impact toughness of the cemented carbide. The bending strength of the obtained hard alloy can reach more than 2350MPa, the volume ratio of alpha-Co at normal temperature reaches more than 65%, and the effective service time of an alloy product sintered by the process is prolonged by 20-40% through destructive tests. The sintering process not only improves the use efficiency of equipment, but also saves the equipment cost. Meanwhile, the service performance of the hard alloy is greatly improved.
The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must be implemented depending on the above detailed structural features. It should be understood by those skilled in the art that any modifications of the present invention, equivalent substitutions of selected components of the present invention, additions of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.
Claims (10)
1. A tungsten-cobalt hard alloy sintering process is characterized by comprising the following steps: after the sintering heat preservation is finished, sequentially carrying out first furnace cooling, air cooling and second furnace cooling; the sintering at least comprises one section of sintering.
2. The process of claim 1, wherein the sintering comprises a first sintering, a second sintering, a third sintering, a fourth sintering, a fifth sintering, a sixth sintering, and a seventh sintering, which are performed sequentially.
3. The process as claimed in claim 2, wherein the end temperature of the first sintering temperature rise is 190-210 ℃;
preferably, the temperature rise time of the first sintering is 50-70 min;
preferably, the heat preservation time of the first sintering is 50-70 min;
preferably, the end temperature of the second sintering temperature rise is 310-330 ℃;
preferably, the temperature rise time of the second sintering is 75-90 min;
preferably, the holding time of the second sintering is 85-95 min.
4. The process as claimed in claim 2 or 3, wherein the end temperature of the third sintering temperature rise is 390-410 ℃;
preferably, the temperature rise time of the third sintering is 85-95 min;
preferably, the heat preservation time of the third sintering is 85-95 min;
preferably, the end temperature of the fourth sintering temperature rise is 580-620 ℃;
preferably, the temperature rise time of the fourth sintering is 95-105 min;
preferably, the heat preservation time of the fourth sintering is 55-65 min.
5. The process according to any of claims 2-4, wherein the end temperature of the fifth sintering temperature rise is 780-820 ℃;
preferably, the temperature rise time of the fifth sintering is 55-65 min;
preferably, the heat preservation time of the fifth sintering is 25-35 min.
6. The process as claimed in any one of claims 2 to 5, wherein the end point temperature of the sixth sintering temperature rise is 1230-;
preferably, the temperature rise time of the sixth sintering is 110-130 min;
preferably, the holding time of the sixth sintering is 55-65 min.
7. The process according to any one of claims 2-6, wherein the end point temperature of the seventh sintering ramp is 1420-;
preferably, the temperature rise time of the seventh sintering is 85-95 min;
preferably, the heat preservation time of the seventh sintering is 70-80 min.
8. The process as claimed in any one of claims 1 to 7, wherein the end temperature of the first furnace cooling is 730- > 770 ℃;
preferably, the time for the first furnace cooling is 380-420 min.
9. The process according to any one of claims 1-8, wherein the air cooling end point temperature is 380-420 ℃;
preferably, the air cooling time is 25-35 min;
preferably, the air cooling is performed under a protective atmosphere;
preferably, the protective atmosphere comprises nitrogen and/or an inert gas;
preferably, the purity of the gas in the protective atmosphere is more than or equal to 99.99 percent;
preferably, the end temperature of the second furnace cooling is 80-100 ℃.
10. The process according to any one of claims 1 to 9, wherein the process comprises: after the sintering heat preservation is finished, sequentially carrying out first furnace cooling, air cooling and second furnace cooling; the sintering at least comprises a section of sintering;
the sintering comprises a first sintering, a second sintering, a third sintering, a fourth sintering, a fifth sintering, a sixth sintering and a seventh sintering which are sequentially carried out; the end temperature of the first sintering temperature rise is 190-210 ℃; the temperature rise time of the first sintering is 50-70 min; the heat preservation time of the first sintering is 50-70 min; the end temperature of the second sintering temperature rise is 310-330 ℃; the temperature rise time of the second sintering is 75-90 min; the heat preservation time of the second sintering is 85-95 min; the end temperature of the third sintering temperature rise is 390-410 ℃; the temperature rise time of the third sintering is 85-95 min; the heat preservation time of the third sintering is 85-95 min; the end temperature of the fourth sintering temperature rise is 580-620 ℃; the temperature rise time of the fourth sintering is 95-105 min; the heat preservation time of the fourth sintering is 55-65 min; the terminal temperature of the fifth sintering temperature rise is 780-820 ℃; the temperature rise time of the fifth sintering is 55-65 min; the heat preservation time of the fifth sintering is 25-35 min; the end temperature of the sixth sintering temperature rise is 1230-; the temperature rise time of the sixth sintering is 110-130 min; the heat preservation time of the sixth sintering is 55-65 min; the terminal temperature of the seventh sintering temperature rise is 1420-1450 ℃; the temperature rise time of the seventh sintering is 85-95 ℃; the heat preservation time of the seventh sintering is 70-80 min; the end temperature of the first furnace cooling is 730-770 ℃; the time for cooling the first furnace is 380-420 min; the air cooling end temperature is 380-420 ℃; the air cooling time is 25-35 min; and the end temperature of the second furnace cooling is 80-100 ℃.
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