A hot work steel cemented carbide material and a method for producing the same

Abstract

This invention belongs to the technical field of steel-bonded cemented carbide, specifically relating to a hot-work steel-bonded cemented carbide material and its preparation method. The hot-work steel-bonded cemented carbide provided by this invention has tungsten carbide as its hard phase, with a weight percentage of 25-45 wt%. The remainder is a steel matrix binder phase, with the following components and weight percentages: chromium (2.0-5.5) wt%, molybdenum (3.0-6.0) wt%, nickel (0.8-2.8) wt%, carbon (0.3-0.6) wt%, and the balance being iron. The preparation method and steps include batching and ball milling, slurry treatment, pressing, sintering, forging and annealing, machining, and heat treatment. The hot-work steel-bonded cemented carbide obtained by this invention possesses excellent thermal stability, hardness, and wear resistance, and can replace traditional hot-work die materials, thus improving service life.

Description

Technical Field

[0001] This invention belongs to the field of steel-structured cemented carbide technology, specifically relating to a hot-work steel-structured cemented carbide material and its preparation method. Background Technology

[0002] Steel-bonded cemented carbide, or simply steel-bonded alloy, is a steel-based composite material with a refractory metal hard compound as the hard phase and steel as the binder phase. The hard phase of steel-bonded alloys typically includes tungsten carbide and titanium carbide, while the steel matrix of the binder phase includes carbon steel, alloy tool steel, high-speed steel, stainless steel, and high-manganese steel. Steel-bonded alloys are an engineering material that falls between steel and cemented carbide, possessing both the high hardness and wear resistance of cemented carbide and the cold and hot workability of alloy steel.

[0003] Hot work die materials are mainly used in high-temperature forming processes. They refer to materials suitable for making dies for hot deformation of metals, such as hot forging dies, hot extrusion dies, die casting dies, and hot upsetting dies. Because hot work dies operate under high temperature and high pressure conditions for extended periods, the die materials are required to have high strength, hardness, and thermal stability, especially high thermal strength, thermal fatigue resistance, toughness, and wear resistance.

[0004] Common hot work die materials include H13, 3Cr2W8V, 5CrMnMo, and high-speed steel. However, these materials all have their limitations. For example, H13's strength decreases significantly above 650℃, its wear resistance is insufficient under high impact wear, and its thermal fatigue life decreases under complex cyclic conditions. 3Cr2W8V is prone to cracking in complex-shaped dies, and its wear resistance decreases and its thermal fatigue life is insufficient under long-term cyclic conditions. 5CrMnMo has insufficient high-temperature strength, its performance decreases significantly above 600℃, its wear resistance is average, and its hardenability is limited. Summary of the Invention

[0005] To address the problems existing in the background technology, this invention proposes a hot-work steel-bonded cemented carbide material and its preparation method, which still has high thermal stability, hardness and wear resistance under high temperature conditions, and is mainly used for hot stamping, hot upsetting, hot extrusion, hot rolling rolls, etc.

[0006] The technical solution of the present invention is as follows:

[0007] A hot-work steel-bonded cemented carbide is manufactured using powder metallurgy methods and processes. Its hard phase is tungsten carbide, with a weight percentage of 25-45 wt%, and the remainder is a steel matrix binder phase. The components and weight percentages of the binder phase are chromium (2.0-5.5) wt%, molybdenum (3.0-6.0) wt%, nickel (0.8-2.8) wt%, carbon (0.3-0.6) wt%, and the balance is iron.

[0008] Preferably, the hard phase of the hot-work steel-bonded cemented carbide is tungsten carbide, and the raw material is tungsten carbide powder.

[0009] The alloying elements selected for the steel matrix in the binder phase include chromium (Cr), molybdenum (Mo), and nickel (Ni). Chromium is an extremely important alloying element in steel alloys. Chromium can improve the hardenability of the steel matrix and improve the alloy's heat resistance, tempering resistance, and oxidation resistance. Molybdenum can improve hardenability, red hardness, and prevent temper brittleness. Nickel can improve the alloy's impact toughness, bending strength, and thermal shock resistance.

[0010] Preferably, in the hot-work steel-bonded hard alloy binder phase, the chromium raw material is selected from ferrochrome powder, the molybdenum raw material is selected from ferromolybdenum powder, the nickel raw material is selected from nickel powder, and the carbon is selected from carbon black.

[0011] More preferably, the tungsten carbide powder has a particle size of 2-5 micrometers, a total carbon content of 5.90-6.10%, and a free carbon content of less than 0.10%.

[0012] More preferably, the ferrochrome powder has a chromium content of 55-60% and a carbon content of 7.5-8.2%, the ferromolybdenum powder has a molybdenum content of 55-60%, and the nickel powder is electrolytic nickel powder or carbonyl nickel powder with a purity of ≥99.9%.

[0013] A method for preparing a hot-work steel-bonded cemented carbide material includes the following steps:

[0014] (1) Ball milling: Mix tungsten carbide powder, ferrochrome powder, ferromolybdenum powder, nickel powder, carbon black and iron powder, load them into a ball mill, and ball mill them thoroughly to obtain a slurry;

[0015] (2) Slurry treatment: The ball-milled slurry is settled, dried, and sieved to obtain mixed powder;

[0016] (3) Pressing: Add the mixed powder obtained in step (2) to the forming agent, mix thoroughly, dry and press to obtain a pressed blank;

[0017] (4) Sintering: The pressed blank obtained in step (3) is sintered in a vacuum sintering furnace and cooled in the furnace;

[0018] (5) Forging and annealing: After sintering, annealing is performed, or forging is performed first and then annealing is performed to obtain steel-bonded blanks;

[0019] (6) Processing: The steel bond blank is processed by turning, milling, planing, drilling, tapping, electrical discharge machining, etc., to obtain the steel bond part;

[0020] (7) Heat treatment: The processed steel alloy parts are quenched and tempered to obtain hot work steel hard alloy.

[0021] (8) Inspection: Measurement, inspection and packaging shall be carried out before leaving the warehouse.

[0022] Preferably, in step (1), the ball-to-material ratio during ball milling is (2-4):1, the ball milling time is 20-36 hours, the ball milling medium is anhydrous alcohol, and a small amount (0.1%) of the surfactant oleic acid is added to the ball milling medium.

[0023] Preferably, in step (2), after the slurry settles, the upper clear liquid is extracted and returned for recycling. The settled slurry is loaded into a dryer for drying, and the dried mixture is sieved in a timely manner.

[0024] Preferably, the temperature of the dryer in step (2) is 80-100℃, and the dried product is sieved to a mesh size of 100-120.

[0025] Preferably, the molding agent added to the mixed powder in step (3) is paraffin wax or synthetic rubber, wherein the synthetic rubber is styrene-butadiene rubber or cis-butadiene rubber; the amount of paraffin wax added is 3 to 4% of the mass of the mixed powder, and the amount of rubber added is 2% of the mass of the mixed powder.

[0026] Preferably, the pressing in step (3) is performed using steel mold pressing or cold isostatic pressing.

[0027] Preferably, the sintering temperature in step (4) is 1250-1350℃ and the holding time is 10-60 minutes.

[0028] Preferably, the heat treatment in step (7) adopts a high quenching and high tempering process, with a quenching temperature of 950~1100℃, a holding time of 1~2 minutes / mm, a tempering temperature of 450~650℃, tempering 2~4 times, a holding time of 1~2 hours each time, and cooling with the furnace.

[0029] Preferably, grinding may be performed in step (7) if necessary.

[0030] The present invention also provides the application of the above-mentioned hot work steel-bonded cemented carbide material in hot stamping, hot upsetting, hot extrusion, and hot rolling rolls.

[0031] The present invention has the following beneficial effects:

[0032] 1. This invention uses powder metallurgy to rationally select and proportion the alloying elements of the steel matrix in the steel-bonded binder phase, and employs high-temperature quenching and multiple high-temperature tempering processes for heat treatment to prepare a hot-work steel-bonded hard alloy material with excellent thermal stability, hardness, and wear resistance.

[0033] 2. The hot work steel-bonded cemented carbide material prepared by this invention fully leverages the advantages of steel-bonded alloys. It possesses both the high hardness and high wear resistance of cemented carbide and the machinability of alloy steel, especially its excellent high-temperature performance, which improves wear resistance and thermal stability. It can replace traditional hot work die materials and extend service life. Attached Figure Description

[0034] Figure 1 This is a production process flow diagram. Detailed Implementation

[0035] To make the present invention clearer and more understandable, the technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the given embodiments are only one of the implementation methods and do not represent all embodiments.

[0036] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art.

[0037] Example 1:

[0038] A hot-work steel-bonded cemented carbide material and its preparation method, comprising the following steps:

[0039] The hard phase of the steel-bonded alloy is selected as tungsten carbide, with a weight percentage of 30%, and the weight percentage of the matrix binder phase is 70%. The weight percentage of each alloy component in the binder phase is as follows: chromium (Cr): 2.2 wt%, molybdenum (Mo): 4.0 wt%, nickel (Ni): 0.8 wt%, carbon (C): 0.3 wt%, with the balance being iron (Fe). The chromium raw material is selected from ferrochrome powder, the molybdenum raw material is selected from ferromolybdenum powder, the nickel raw material is selected from nickel powder, and the carbon is selected from carbon black. The tungsten carbide powder has a particle size of 2-5 micrometers, a total carbon content of 5.90-6.10%, and a free carbon content of less than 0.10%. The ferrochrome powder has a chromium content of 55-60% and a carbon content of 7.5-8.2%. The ferromolybdenum powder has a molybdenum content of 55-60%. The nickel powder is electrolytic nickel powder or carbonyl nickel powder with a purity of greater than or equal to 99.9%.

[0040] Preparation process as follows Figure 1 As shown.

[0041] (1) Batching and ball milling: According to the proportion and content of the ingredients, weigh out tungsten carbide powder, ferrochrome powder, ferromolybdenum powder, nickel powder and iron powder respectively. Mix the tungsten carbide powder, ferrochrome powder, ferromolybdenum powder, nickel powder and iron powder, load them into the ball mill, the ball-to-material ratio is 3:1, and ball mill for 36 hours to obtain slurry;

[0042] (2) Slurry treatment: The ball-milled slurry is settled, the upper clear liquid is extracted and returned for recycling, the settled slurry is loaded into a dryer for drying, and the dried mixture is sieved in time to obtain mixed powder;

[0043] (3) Pressing: The mixed powder obtained in step (2) is added to a molding agent, wherein the molding agent is styrene-butadiene rubber, and the amount added is 2% of the mass of the mixed powder; after thorough mixing and drying, it is pressed to obtain a pressed blank;

[0044] (4) Sintering: The pressed blank obtained in step (3) is sintered without pressure in a vacuum sintering furnace. The sintering temperature is controlled at 1290-1320℃, the holding time is 30 minutes, and the blank is cooled with the furnace.

[0045] (5) Forging and annealing: After sintering, forging is carried out first and then annealing to obtain steel-bonded blanks;

[0046] (6) Processing: The steel bond blank is processed to obtain the steel bond part;

[0047] (7) Heat treatment: Quenching and tempering the processed steel bond parts. The quenching temperature is 1000-1100℃ and the tempering temperature is 500-600℃. Tempering is performed 3 times, and the holding time is 2 hours each time to obtain hot work steel bond hard alloy.

[0048] (8) Inspection: Measurement, inspection and packaging are carried out before leaving the warehouse.

[0049] Example 2:

[0050] A hot-work steel-bonded cemented carbide material and its preparation method, comprising the following steps:

[0051] The hard phase of the steel-bonded alloy is selected as tungsten carbide, which accounts for 40% by weight, and the matrix binder phase accounts for 60% by weight. The weight percentage of each alloy component in the binder phase is chromium (Cr): 3.0 wt%, molybdenum (Mo): 5.0 wt%, nickel (Ni): 1.0 wt%, carbon (C): 0.4 wt%, and the balance is iron (Fe).

[0052] (1) Batching and ball milling: According to the proportion and content of the ingredients, weigh out tungsten carbide powder, ferrochrome powder, ferromolybdenum powder, nickel powder and iron powder respectively. Mix the tungsten carbide powder, ferrochrome powder, ferromolybdenum powder, nickel powder and iron powder, load them into the ball mill, the ball-to-material ratio is 3:1, and ball mill for 36 hours to obtain slurry;

[0053] (2) Slurry treatment: The ball-milled slurry is settled, the upper clear liquid is extracted and returned for recycling, the settled slurry is loaded into a dryer for drying, and the dried mixture is sieved in time to obtain mixed powder;

[0054] (3) Pressing: The mixed powder obtained in step (2) is added to a molding agent, wherein the molding agent is styrene-butadiene rubber, and the amount added is 2% of the mass of the mixed powder; after thorough mixing and drying, it is pressed to obtain a pressed blank;

[0055] (4) Sintering: The pressed blank obtained in step (3) is sintered without pressure in a vacuum sintering furnace. The sintering temperature is controlled at 1280-1310℃, the holding time is 30 minutes, and the blank is cooled with the furnace.

[0056] (5) Forging and annealing: After sintering, forging is carried out first and then annealing to obtain steel-bonded blanks;

[0057] (6) Processing: The steel bond blank is processed to obtain the steel bond part;

[0058] (7) Heat treatment: Quenching and tempering the processed steel bond parts. The quenching temperature is 1000-1100℃ and the tempering temperature is 500-600℃. Tempering is performed 3 times, and the holding time is 2 hours each time to obtain hot work steel bond hard alloy.

[0059] (8) Inspection: Measurement, inspection and packaging are carried out before leaving the warehouse.

[0060] Experimental Example 1:

[0061] The mechanical properties of Examples 1 and 2 were measured, and the results are shown in Table 1:

[0062] Table 1 Mechanical properties of steel-bonded alloys obtained in Examples 1 and 2

[0063]

[0064] Comparative Example 1:

[0065] The fabrication of a traditional steel-bonded cemented carbide material includes the following steps:

[0066] The hard phase of the steel-bonded alloy is selected as tungsten carbide, which accounts for 30% by weight. The matrix binder phase accounts for 70% by weight. The weight percentage of each alloy component in the binder phase is chromium (Cr): 1.0 wt%, molybdenum (Mo): 0.5 wt%, nickel (Ni): 0.8 wt%, carbon (C): 0.4 wt%, and the balance is iron (Fe).

[0067] (1) Ball milling: Weigh tungsten carbide powder, ferrochrome powder, ferromolybdenum powder, nickel powder, carbon black and iron powder according to the proportion and content. Load the weighed raw material powders into the ball mill. The ball-to-material ratio is 3:1 and the ball milling time is 36 hours.

[0068] (2) Slurry treatment: After sedimentation, drying and sieving, the dried mixed powder is obtained;

[0069] (3) Pressing: Add the ball-milled mixed powder to the forming agent, dry it, and then press it;

[0070] (4) Sintering: Sintering is carried out in a vacuum sintering furnace. The sintering temperature is controlled at 1290-1320℃, the holding time is 30 minutes, and the furnace is cooled.

[0071] (5) Forging and annealing: After sintering, forging is performed first and then annealing to obtain steel-bonded blanks;

[0072] (6) Processing, such as processing the steel bond blank as needed;

[0073] (7) Heat treatment: Quenching and tempering the processed steel alloy parts. The quenching temperature is 980-1050℃ and the holding time is 1-2 minutes / mm. The tempering temperature is 180-200℃ and the holding time is 2 hours.

[0074] (8) Inspection: The performance of the prepared steel-structured cemented carbide sample is tested.

[0075] Comparative Example 2:

[0076] The fabrication of a traditional steel-bonded cemented carbide material includes the following steps:

[0077] The hard phase of the steel-bonded alloy is selected as tungsten carbide, which accounts for 40% by weight. The matrix binder phase accounts for 60% by weight. The weight percentage of each alloy component in the binder phase is chromium (Cr): 1.0 wt%, molybdenum (Mo): 0.5 wt%, nickel (Ni): 1.6 wt%, carbon (C): 0.6 wt%, and the balance is iron (Fe).

[0078] (1) Ball milling: Weigh tungsten carbide powder, ferrochrome powder, ferromolybdenum powder, nickel powder, carbon black and iron powder according to the proportion and content. Load the weighed raw material powders into the ball mill. The ball-to-material ratio is 3:1 and the ball milling time is 36 hours.

[0079] (2) Slurry treatment: After sedimentation, drying and sieving, the dried mixed powder is obtained;

[0080] (3) Pressing: Add the ball-milled mixed powder to the forming agent, dry it, and then press it;

[0081] (4) Sintering: Sintering is carried out in a vacuum sintering furnace. The sintering temperature is controlled at 1290-1320℃ and the holding time is 10-60 minutes. The furnace is then cooled.

[0082] (5) Forging and annealing: After sintering, forging is performed first and then annealing to obtain steel-bonded blanks;

[0083] (6) Processing, such as processing the steel bond blank as needed;

[0084] (7) Heat treatment: Quench and temper the processed steel alloy parts. The quenching temperature is 980-1050℃ and the tempering temperature is 180-200℃. Hold for 2 hours.

[0085] (8) Inspection: The performance of the prepared steel-structured cemented carbide sample is tested.

[0086] The mechanical properties of Comparative Example 1 and Comparative Example 2 were measured, and the results are shown in Table 2.

[0087] Table 2 shows the mechanical properties of the steel-bonded alloys obtained in Comparative Example 1 and Comparative Example 2:

[0088]

[0089] The hot work steel-bonded cemented carbide described in this invention not only has high hardness and wear resistance at room temperature, but also maintains high hardness and wear resistance at high temperatures (500-800℃), which greatly improves the service life of hot work dies, parts, etc., and is a good hot work die and engineering material.

[0090] Although embodiments of the invention have been shown and described, those skilled in the art will be able to make various changes, modifications, substitutions and alterations to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A hot-work steel-bonded cemented carbide, characterized in that, Its hard phase is tungsten carbide, with a weight percentage of 25-45 wt%, and the remainder is a steel matrix binder phase. The components and weight percentages of the binder phase are chromium (2.0-5.5) wt%, molybdenum (3.0-6.0) wt%, nickel (0.8-2.8) wt%, carbon (0.3-0.6) wt%, and the balance is iron. The preparation method of the hot-work steel-bonded cemented carbide is as follows: (1) Batching and ball milling: Mix tungsten carbide powder, ferrochrome powder, ferromolybdenum powder, nickel powder, carbon black and iron powder, load them into a ball mill, and ball mill them thoroughly to obtain a slurry; (2) Slurry treatment: The ball-milled slurry is settled, dried, and sieved to obtain mixed powder; (3) Pressing: Add the mixed powder obtained in step (2) to the forming agent, mix thoroughly, dry and press to obtain a pressed blank; (4) Sintering: The pressed blank obtained in step (3) is sintered in a vacuum sintering furnace and cooled with the furnace; (5) Forging and annealing: After sintering, annealing is performed, or forging is performed first and then annealing is performed to obtain steel-bonded blanks; (6) Processing: The steel bond blank is processed by turning, milling, planing, drilling, tapping or electrical discharge machining to obtain the steel bond part; (7) Heat treatment: The processed steel bond parts are quenched and tempered to obtain hot work steel bond hard alloy; the quenching and tempering adopts the high quenching and high tempering process, the quenching temperature is 950~1100℃, the holding time is 1~2 minutes / mm, the tempering temperature is 450~650℃, tempering is 2~4 times, the holding time is 1~2 hours each time, and the furnace is cooled. (8) Inspection: Measurement, inspection and packaging shall be carried out before leaving the warehouse.

2. The hot-work steel-bonded cemented carbide according to claim 1, characterized in that, The hard phase of the hot-work steel-bonded cemented carbide is tungsten carbide, and the raw material is tungsten carbide powder; in the binder phase of the hot-work steel-bonded cemented carbide, the chromium raw material is ferrochrome powder, the molybdenum raw material is ferromolybdenum powder, the nickel raw material is nickel powder; and the carbon is carbon black.

3. The hot-work steel-bonded cemented carbide according to claim 2, characterized in that, The tungsten carbide powder has a particle size of 2-5 micrometers, a total carbon content of 5.90-6.10%, and a free carbon content of less than 0.10%; the ferrochrome powder has a chromium content of 55-60% and a carbon content of 7.5-8.2%; the ferromolybdenum powder has a molybdenum content of 55-60%; and the nickel powder is electrolytic nickel powder or carbonyl nickel powder with a purity of ≥99.9%.

4. The method for preparing hot-work steel-bonded cemented carbide as described in any one of claims 1-3, characterized in that, The preparation method includes the following steps: (1) Batching and ball milling: Mix tungsten carbide powder, ferrochrome powder, ferromolybdenum powder, nickel powder, carbon black and iron powder, load them into a ball mill, and ball mill them thoroughly to obtain a slurry; (2) Slurry treatment: The ball-milled slurry is settled, dried, and sieved to obtain mixed powder; (3) Pressing: Add the mixed powder obtained in step (2) to the forming agent, mix thoroughly, dry and press to obtain a pressed blank; (4) Sintering: The pressed blank obtained in step (3) is sintered in a vacuum sintering furnace and cooled with the furnace; (5) Forging and annealing: After sintering, annealing is performed, or forging is performed first and then annealing is performed to obtain steel-bonded blanks; (6) Processing: The steel bond blank is processed by turning, milling, planing, drilling, tapping or electrical discharge machining to obtain the steel bond part; (7) Heat treatment: The processed steel bond parts are quenched and tempered to obtain hot work steel bond hard alloy; the quenching and tempering adopts the high quenching and high tempering process, the quenching temperature is 950~1100℃, the holding time is 1~2 minutes / mm, the tempering temperature is 450~650℃, tempering is 2~4 times, the holding time is 1~2 hours each time, and the furnace is cooled. (8) Inspection: Measurement, inspection and packaging shall be carried out before leaving the warehouse.

5. The preparation method according to claim 4, characterized in that, In step (1), the ball-to-material ratio during ball milling is (2-4):1, the ball milling time is 20-36 hours, the ball milling medium is anhydrous alcohol, and 0.1% of the total mass of the ball milling medium is added to the ball milling medium as a surfactant, oleic acid.

6. The preparation method according to claim 4, characterized in that, In step (2), after the slurry settles, the upper clear liquid is extracted and returned for recycling. The settled slurry is loaded into a dryer for drying, and the dried mixture is sieved in time. The temperature of the dryer is 80-100℃, and the sieve after drying is selected to be 100-120 mesh.

7. The preparation method according to claim 4, characterized in that, The molding agent added to the mixed powder in step (3) is paraffin wax or synthetic rubber, wherein the synthetic rubber is styrene-butadiene rubber or cis-butadiene rubber; the amount of paraffin wax added is 3 to 4% of the mass of the mixed powder, and the amount of rubber added is 2% of the mass of the mixed powder; the pressing in step (3) is steel mold pressing or cold isostatic pressing.

8. The preparation method according to claim 4, characterized in that, In step (4), the sintering temperature is 1250-1350℃ and the holding time is 10-60 minutes.

9. The application of the hot work steel-bonded cemented carbide as described in any one of claims 1-3 or the hot work steel-bonded cemented carbide obtained by the preparation method as described in any one of claims 4-8 in hot stamping, hot upsetting, hot extrusion, and hot rolling mill rolls.

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