A method of post-treatment of carburized cemented carbide

Abstract

The present application belongs to the field of powder metallurgy, and particularly relates to a post-processing method of carburized hard alloy, which comprises the following steps: coating the carburized hard alloy with fiber paper, and combining a special vacuum sintering process to reduce the carbon content of the carburized hard alloy to reach the two-phase zone standard. The post-processing method can convert low-performance unqualified products into qualified products without damage, thereby greatly improving the product qualification rate and production efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of powder metallurgy, and particularly relates to a post-processing method of carburized cemented carbide. BACKGROUND

[0002] Cemented carbide is a kind of cermet composite material prepared by powder metallurgy process, in which refractory hard compound is used as hard matrix and transition metal is used as tough bonding phase. Because of the high strength and high toughness of cemented carbide, it is widely used in oil and gas drilling, geological exploration, mine exploitation, roller, die material, cutting tool, wear-resistant parts and other fields, and plays an important role in promoting national industrial manufacturing and national economic development.

[0003] Carbon content control is an important means of quality control of cemented carbide. When the carbon content is too low, the alloy will produce hard and brittle decarburized phase (eta phase), and when the carbon content is too high, carburized phase (C phase) in the form of free carbon will be produced. The presence of decarburized phase and carburized phase will deteriorate the performance of the alloy. When the carbon content is appropriate, the cemented carbide is composed of WC+Co two phases, at this time the alloy shows good strength, toughness and other comprehensive performance. In actual production, the carbon content is strictly controlled, but the carburization phenomenon may still occur due to various problems, and once carburization occurs, the whole batch of products will face the risk of scrapping. SUMMARY

[0004] In order to solve the problems in the prior art, the main purpose of the present application is to provide a post-processing method of carburized cemented carbide, which reduces the carbon content of carburized cemented carbide to reach the two-phase region standard. The use of the processing method can reduce the free carbon of carburized products, so that the products return to the two-phase region and meet the qualified standard, greatly improving the product qualification rate and production efficiency.

[0005] In order to solve the above technical problems, according to one aspect of the present application, the present application provides the following technical scheme:

[0006] A post-processing method of carburized cemented carbide, comprising the following steps:

[0007] S1. wrapping the carburized cemented carbide with fiber paper;

[0008] S2. placing the carburized cemented carbide wrapped with fiber paper in a boat and putting it into a sintering furnace for vacuum sintering; the process parameters of vacuum sintering are as follows:

[0009] starting to heat at a heating rate of 5-10 ℃ / min, heating to 380-420 ℃, and keeping the temperature for 15-25 min;

[0010] The hydrogen gas with the pressure of 0.25-0.35 MPa is introduced into the furnace, and the temperature is continuously increased at the temperature increasing rate of 3-6 ℃ / min, and when the temperature reaches 590-610 ℃, the temperature is kept for 0.75-1.25 h, and then the vacuum is extracted to 1 bar;

[0011] The temperature is continuously increased at the temperature increasing rate of 3-6 ℃ / min to 1240-1260 ℃, and the temperature is kept for 25-35 min, and then the furnace is cooled to normal temperature.

[0012] As a preferred scheme of the post-processing method of the carburized cemented carbide, the carburized cemented carbide is a carburized WC-Co product.

[0013] As a preferred scheme of the post-processing method of the carburized cemented carbide, in the step S1, the fiber paper is an aluminum silicate fiber paper or an aluminum oxide fiber paper.

[0014] As a preferred scheme of the post-processing method of the carburized cemented carbide, in the step S2, before the vacuum sintering, the nitrogen gas is used to replace the atmosphere in the furnace for 3 times to ensure that the oxygen is excluded.

[0015] The beneficial effects of the present application are as follows:

[0016] The present application provides a post-processing method of carburized cemented carbide, which coats the carburized cemented carbide with fiber paper, and combines a special vacuum sintering process to reduce the carbon content of the carburized cemented carbide to reach the two-phase zone standard. The low-performance unqualified products can be converted into qualified products without damage by using the post-processing method, which greatly improves the product qualification rate and production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor based on the drawings shown.

[0018] Figure 1 It is a comparison picture of the product before and after processing in the embodiment 1 of the present application;

[0019] Figure 2 It is a comparison picture of the product before and after processing in the embodiment 2 of the present application;

[0020] Figure 3 It is a picture of the product after processing in the comparative example 1 of the present application;

[0021] Figure 4 It is a picture of the product after processing in the comparative example 2 of the present application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments will be described clearly and completely below. Obviously, the described embodiments are only a part but not all of the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0023] The main purpose of the present application is to provide a post-treatment method of carburized cemented carbide, which reduces the carbon content of the carburized cemented carbide to reach the two-phase region standard. The treatment method can reduce the free carbon content of the carburized product, return the product to the two-phase region, and reach the qualified standard, thereby greatly improving the product qualification rate and production efficiency.

[0024] According to an aspect of the present application, the present application provides the following technical solutions:

[0025] A post-treatment method of carburized cemented carbide, comprising the following steps:

[0026] S1. wrapping the carburized cemented carbide with fiber paper;

[0027] S2. placing the carburized cemented carbide wrapped with fiber paper in a boat and putting it into a sintering furnace for vacuum sintering; the process parameters of vacuum sintering are:

[0028] starting to heat at a heating rate of 5-10℃ / min, heating to 380-420℃, and holding for 15-25min; specifically, the heating rate can be, for example but not limited to, any one of 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min or a range between any two of them; the holding temperature can be, for example but not limited to, any one of 380℃, 390℃, 400℃, 410℃, 420℃ or a range between any two of them; and the holding time can be, for example but not limited to, any one of 15min, 16min, 17min, 18min, 19min, 20min, 21min, 22min, 23min, 24min, 25min or a range between any two of them;

[0029] hydrogen is introduced into the furnace at a pressure of 0.25-0.35 MPa, and the temperature is continued to be raised at a rate of 3-6℃ / min, and when the temperature reaches 590-610℃, the temperature is maintained for 0.75-1.25 h, and then the furnace is vacuumized to 1 bar; specifically, the hydrogen pressure can be, for example but not limited to, any one of 0.25 MPa, 0.30 MPa, 0.35 MPa or a range between any two of them; the temperature raising rate can be, for example but not limited to, any one of 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min or a range between any two of them; the temperature maintaining temperature can be, for example but not limited to, any one of 590℃, 595℃, 600℃, 605℃, 610℃ or a range between any two of them; the temperature maintaining time can be, for example but not limited to, any one of 0.75 h, 1.0 h, 1.25 h or a range between any two of them;

[0030] the temperature is continued to be raised at a rate of 3-6℃ / min to 1240-1260℃, and maintained for 25-35 min, and then the furnace is cooled to room temperature. Specifically, the temperature raising rate can be, for example but not limited to, any one of 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min or a range between any two of them; the temperature maintaining temperature can be, for example but not limited to, any one of 1240℃, 1245℃, 1250℃, 1255℃, 1260℃ or a range between any two of them; the temperature maintaining time can be, for example but not limited to, any one of 25 min, 26 min, 27 min, 28 min, 29 min, 30 min, 31 min, 32 min, 33 min, 34 min, 35 min or a range between any two of them;

[0031] As a preferred scheme of the post-treatment method of the carburized cemented carbide, in the step S1, the fiber paper is an aluminum silicate fiber paper or an aluminum oxide fiber paper.

[0032] The carburized cemented carbide is a carburized WC-Co product.

[0033] As a preferred scheme of the post-treatment method of the carburized cemented carbide, in the step S1, the fiber paper is an aluminum silicate fiber paper or an aluminum oxide fiber paper.

[0034] As a preferred scheme of the post-treatment method of the carburized cemented carbide, in the step S2, before vacuum sintering, the atmosphere in the furnace is replaced with nitrogen for 3 times to ensure that oxygen is excluded.

[0035] The technical scheme of the present application is further described below in combination with specific embodiments.

[0036] Embodiment 1

[0037] A post-treatment method of a carburized cemented carbide, comprising the following steps:

[0038] S1. The carburized WC-10Co cemented carbide (as shown in (a) of Figure 1 ) was coated with an aluminum oxide fiber paper;

[0039] S2. The carburized WC-10Co cemented carbide coated with the fiber paper was placed in a boat and put into a sintering furnace. The atmosphere in the furnace was replaced with nitrogen for 3 times to ensure that oxygen was excluded and then vacuum sintering was performed. The process parameters for vacuum sintering were as follows:

[0040] The temperature was raised at a rate of 7°C / min to 400°C, and the temperature was maintained for 20 min;

[0041] Hydrogen was introduced into the furnace at a pressure of 0.3 MPa, and the temperature was continued to be raised at a rate of 3°C / min. When the temperature reached 600°C, the temperature was maintained for 1.0 h, and then the vacuum was drawn to 1 bar;

[0042] The temperature was continued to be raised at a rate of 3°C / min to 1250°C, and the temperature was maintained for 30 min, and then the furnace was cooled to room temperature. The sample A obtained is shown in (b) of Figure 1 , and the carburization phenomenon disappeared.

[0043] Example 2

[0044] A post-treatment method for carburized cemented carbide, comprising the following steps:

[0045] S1. The carburized WC-15Co cemented carbide (as shown in (a) of Figure 2 ) was coated with an aluminum oxide fiber paper;

[0046] S2. The carburized WC-15Co cemented carbide coated with the fiber paper was placed in a boat and put into a sintering furnace. The atmosphere in the furnace was replaced with nitrogen for 3 times to ensure that oxygen was excluded and then vacuum sintering was performed. The process parameters for vacuum sintering were as follows:

[0047] The temperature was raised at a rate of 10°C / min to 400°C, and the temperature was maintained for 20 min;

[0048] Hydrogen was introduced into the furnace at a pressure of 0.3 MPa, and the temperature was continued to be raised at a rate of 5°C / min. When the temperature reached 600°C, the temperature was maintained for 1.0 h, and then the vacuum was drawn to 1 bar;

[0049] The temperature was continued to be raised at a rate of 5°C / min to 1250°C, and the temperature was maintained for 30 min, and then the furnace was cooled to room temperature. The sample B obtained is shown in (b) of Figure 2 , and the carburization phenomenon disappeared.

[0050] Comparative Example 1

[0051] The difference from example 1 is that the carburized WC-10Co cemented carbide is not coated with aluminum silicate fiber paper; sample C is obtained as shown in Figure 3 The product is still in the three-phase region.

[0052] Comparative example 2

[0053] The difference from example 1 is that the vacuum sintering process is: heating to 1250℃ at 3℃ / min, holding for 30min, and then cooling to room temperature with the furnace, to obtain sample D as shown in Figure 4 The product is still in the three-phase region.

[0054] The present application coats the carburized cemented carbide with fiber paper, and combines a special vacuum sintering process to reduce the carbon content of the carburized cemented carbide to reach the two-phase region standard. Comparative examples 1-2 cannot achieve post-processing of the carburized cemented carbide product without using the method described in the present application. Using the post-processing method of the present application, low-performance unqualified products can be converted into qualified products without damage, greatly improving the product qualification rate and production efficiency.

[0055] The above is only a preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation, direct / indirect application in other related technical fields, or use of the content of the present application within the inventive concept of the present application is included in the patent protection scope of the present application.

Claims

1. A method for post-treatment of carburized cemented carbide, characterized in that, The method comprises the following steps: S1. coating the carburized hard alloy with fiber paper; the fiber paper is aluminum silicate fiber paper or aluminum oxide fiber paper; S2. placing the carburized hard alloy coated with fiber paper in a boat and putting it into a sintering furnace for vacuum sintering to reduce the carbon content of the carburized hard alloy to reach the two-phase region standard; the process parameters of the vacuum sintering are as follows: starting to heat at a heating rate of 5-10 ℃ / min, heating to 380-420 ℃, and keeping the temperature for 15-25 min; introducing 0.25-0.35 MPa hydrogen into the furnace, and continuously heating at a heating rate of 3-6 ℃ / min, keeping the temperature for 0.75-1.25 h when the temperature reaches 590-610 ℃, and then vacuumizing to 1 bar; continuously heating at a heating rate of 3-6 ℃ / min to 1240-1260 ℃, keeping the temperature for 25-35 min, and then cooling with the furnace to room temperature.

2. The post-processing method of claim 1, wherein, The carburized hard alloy is a carburized WC-Co product.

3. The post-processing method of claim 1, wherein, In the step S2, the atmosphere in the furnace is replaced with nitrogen for 3 times before vacuum sintering to ensure that oxygen is excluded.

4. The post-processing method of claim 1, wherein, In the step S2, the process parameters of the vacuum sintering are as follows: starting to heat at a heating rate of 8 ℃ / min, heating to 400 ℃, and keeping the temperature for 20 min; introducing 0.3 MPa hydrogen into the furnace, and continuously heating at a heating rate of 5 ℃ / min, keeping the temperature for 1.0 h when the temperature reaches 600 ℃, and then vacuumizing to 1 bar; continuously heating at a heating rate of 5 ℃ / min to 1250 ℃, keeping the temperature for 30 min, and then cooling with the furnace to room temperature.

Images