Powder high-speed steel deep hole drill with high hardness, wear resistance and toughness and preparation method of powder high-speed steel deep hole drill

Abstract

The invention relates to the technical field of metal material processing, in particular to a powder high-speed steel deep hole drill with high hardness, wear resistance and toughness, a drill bit matrix is composed of 1-3% of C, 10-15% of W, 2-5% of Mo, 3-5% of Cr, 9-13% of Co, 3-6% of V and 1.5-2.5% of LaO nanoparticles, and the density is larger than or equal to 99% after hot isostatic pressing sintering; the composite coating is of a TiAlN / TiSiN multi-layer structure, the layer thickness is 2-30 nm, and the layer thickness ratio of TiAlN to TiSiN is 1: 2. The method comprises the following steps: step 1, a preheating stage: the temperature range is 730-845 DEG C, and heat preservation is performed for 30-60 minutes to avoid thermal shock; the pressure is larger than or equal to 150 MPa, the temperature is 1350-1450 DEG C, the heat preservation time is 2-3 hours, and the density is larger than or equal to 99%; 3, in the high-temperature annealing stage, the temperature is controlled to be 850-880 DEG C, and the heat preservation time is 1-2 h / mm; carbides are distributed in a dispersed mode after vacuum annealing, the hardness of a matrix is improved, and the hardness is smaller than or equal to 285HBW after annealing; step 4, quenching; 5, tempering is conducted; step 6, isothermal treatment; and 7, a cooling stage.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material processing, and in particular to a powder high-speed steel deep hole drill with high hardness, wear resistance and toughness and a preparation method thereof. Background Art

[0002] The drill bit used in drilling operations is a critical component of machine tools. It is typically made of high-speed steel (HSS), a high-alloy tool steel containing high amounts of tungsten, chromium, and aluminum, commonly known as sharp steel or white steel. Drilling is a significant component of metal cutting operations, significantly higher than milling. Drilling is an even more common process on certain flexible production lines and machining centers. However, rapid wear of the cutting edge is a significant factor limiting drill quality and drill bit life.

[0003] Application publication number: CN 115971544 A, patent name: A high-speed steel drill bit and its preparation method, which adopts an inner and outer surrounding structure to remove the heat generated by the drill bit during operation to avoid mutual interference through the internal conformal cooling flow channel, thereby achieving uniform heat dissipation and improving the drilling efficiency and service life of the drill bit. A low-power, slow scanning speed laser additive manufacturing process is adopted to reduce the temperature gradient and residual stress during molding. Laser remelting is further combined to solve the deformation and cracking problems of high-speed steel. At the same time, surface laser quenching technology is used to prepare a high-performance high-speed steel drill bit with a hard and wear-resistant surface and a high-strength and high-toughness core. However, the drill bit does not fundamentally solve the problems of traditional carbide drill bits in deep hole machining of cast iron crankshafts, such as rapid tool wear, especially on 5511 high-strength cast iron, and unstable surface quality. At the same time, the traditional ratio of high alloy elements (such as W, Mo, and Co) leads to insufficient toughness, making it difficult to cope with the high impact load of deep hole drilling. At the same time, it cannot solve the problem of high wear resistance and thermal stability of the drill bit material. Therefore, it is necessary to design a powder high-speed steel deep hole drill with high hardness, wear resistance and toughness and its preparation method to solve the above problems. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to propose a powder high-speed steel deep hole drill with high hardness, wear resistance and toughness and a preparation method thereof, so as to solve the problem that the high impact load of deep hole drilling and the drill bit material must have high wear resistance and thermal stability.

[0005] Based on the above objectives, the present invention provides a powder high-speed steel deep hole drill with high hardness, wear resistance and toughness, characterized in that: the drill bit base is composed of C (1-3%), W (10-15%), Mo (2-5%), Cr (3-5%), Co (9-13%), V (3-6%) and 1.5-2.5% La2O3 nanoparticles, and the density is ≥99% after hot isostatic pressing.

[0006] A further improvement of the present invention is that the composite coating is a TiAlN / TiSiN multilayer structure with a layer thickness of 2-30 nm and a layer thickness ratio of TiAlN:TiSiN=1:2, and the friction coefficient is reduced to below 0.3.

[0007] A further improvement of the present invention is: Step 1: Preheating stage, temperature range: 730~845℃, keep warm for 30~60 minutes to avoid thermal shock, heat the blank evenly and prevent internal stress concentration; Step 2: Hot isostatic pressing sintering process: pressure ≥ 150MPa, temperature 1350-1450℃, holding time 2-3 hours, density ≥ 99%; Step 3: High temperature annealing stage, temperature control: 850~880℃, holding time: 1~2 hours / mm, to promote the full dissolution of carbides in austenite, laying the foundation for subsequent spheroidization; after vacuum annealing, carbides are dispersed, improving the hardness of the matrix, and the hardness after annealing is ≤285HBW; Step 4: Quenching; Step 5: Tempering; Step 6: Isothermal treatment; Step 7: Cooling stage.

[0008] A further improvement of the present invention is: vacuum degree monitoring: maintaining a vacuum degree <1×10⁻³ Pa to prevent abnormal precipitation of carbides caused by trace oxygen.

[0009] A further improvement of the present invention is that the quenching process in step 4 is performed at a pressure of ≥150 MPa, a temperature of 1180-1220° C., and a holding time of 2-3 hours.

[0010] A further improvement of the present invention is that the tempering process in step five is carried out at a furnace temperature of 540-560° C., and the final hardness can reach 67-70 HRC.

[0011] A further improvement of the present invention is that the isothermal treatment process in step six is ​​as follows: the temperature and time are: 730~750℃, and the heat preservation is 1~2 hours, which promotes the decomposition of austenite into pearlite, refines the structure, shortens the annealing cycle by more than 50% compared with ordinary annealing, and maintains hardness uniformity.

[0012] A further improvement of the present invention is that the cooling process in step seven is furnace cooling to 500°C and then air cooling, or graded cooling is adopted, such as staying in a salt bath at 600-650°C for 10-20 minutes, to avoid cracking caused by rapid cooling and ensure structural uniformity.

[0013] The drill bit of the present invention fundamentally solves the problems of traditional carbide drill bits in deep hole machining of cast iron crankshafts, such as rapid tool wear, especially unstable surface quality on 5511 high-strength cast iron. At the same time, the high ratio of alloy elements ensures toughness and can cope with the high impact load of deep hole drilling. The drill bit material produced has high wear resistance and thermal stability. DETAILED DESCRIPTION

[0014] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments. Example

[0015] The present invention provides a powder high-speed steel deep hole drill with high hardness, wear resistance and toughness. The drill bit base is composed of C:1%, W:10%, Mo:2%, Cr:3%, Co:9%, V:3% and 1.5% La2O3 nanoparticles. The density is ≥99% after hot isostatic pressing sintering. The composite coating is a TiAlN / TiSiN multilayer structure with a layer thickness of 2-30nm and a layer thickness ratio of TiAlN:TiSiN=1:2.

[0016] Step 1: Preheating stage, temperature range: 730℃, keep warm for 30 minutes to avoid thermal shock; Step 2: Hot isostatic pressing sintering process: pressure ≥150MPa, temperature 1350℃, holding time 2 hours, density ≥99%; Step 3: High temperature annealing stage, temperature control: 850℃, holding time: 1 hour / mm; After vacuum annealing, carbides are dispersed, improving the hardness of the matrix, and the hardness after annealing is ≤285HBW; Step 4: Quenching; Step 5: Tempering; Step 6: Isothermal treatment; Step 7: Cooling stage; Vacuum degree monitoring: Maintain vacuum degree <1×10⁻³ Pa to prevent trace oxygen from causing abnormal precipitation of carbides; The quenching process of step 4 is pressure ≥150MPa , 1180℃, holding time 2 hours; the tempering process in step five is a furnace temperature of 540℃, and the final hardness can reach 67HRC; the isothermal treatment process in step six is ​​a temperature and time of 730℃, holding time 1 hour, which promotes the decomposition of austenite into pearlite and refines the structure; the cooling stage process in step seven is furnace cooling to 500℃ and then air cooling, or graded cooling is used, and it stays in a 600℃ salt bath for 10 minutes. Example

[0017] The present invention provides a powder high-speed steel deep hole drill with high hardness, wear resistance and toughness. The drill base is composed of C: 2%, W: 14.3%, Mo: 2.5%, Cr: 3.75%, Co: 11%, V: 5% and 2% La2O3 nanoparticles. The density is ≥ 99% after hot isostatic pressing sintering. The composite coating is a TiAlN / TiSiN multilayer structure with a layer thickness of 2-30nm and a layer thickness ratio of TiAlN:TiSiN=1:2.

[0018] Step 1: Preheating stage, temperature range: 785℃, keep warm for 45 minutes to avoid thermal shock; Step 2: Hot isostatic pressing sintering process: pressure ≥150MPa, temperature 1400℃, holding time 2.5 hours, density ≥99%; Step 3: High temperature annealing stage, temperature control: 865℃, holding time: 1.5 hours / mm; After vacuum annealing, carbides are dispersed, improving the hardness of the matrix, and the hardness after annealing is ≤285HBW; Step 4: Quenching; Step 5: Tempering; Step 6: Isothermal treatment; Step 7: Cooling stage; Vacuum degree monitoring: Maintain vacuum degree <1×10⁻³ Pa to prevent trace oxygen from causing abnormal precipitation of carbides; The quenching process of step 4 is pressure ≥150MPa , 1200℃, holding time 2.5 hours; the tempering process in step five is a furnace temperature of 550℃, and the final hardness can reach 68HRC; the isothermal treatment process in step six is ​​a temperature and time: 740℃, holding time 1.5 hours, which promotes the decomposition of austenite into pearlite and refines the structure; the cooling stage process in step seven is furnace cooling to 500℃ and then air cooling, or graded cooling is used, and it stays in a 620℃ salt bath for 15 minutes. Example

[0019] The present invention provides a powder high-speed steel deep-hole drill with high hardness, wear resistance and toughness. The drill base is composed of C:3%, W:15%, Mo:5%, Cr:5%, Co:13%, V:6% and 2.5% La2O3 nanoparticles. The density is ≥99% after hot isostatic pressing sintering. The composite coating is a TiAlN / TiSiN multilayer structure with a layer thickness of 2-30nm and a layer thickness ratio of TiAlN:TiSiN=1:2.

[0020] Step 1: Preheating stage, temperature range: 845℃, keep warm for 60 minutes to avoid thermal shock; Step 2: Hot isostatic pressing sintering process: pressure ≥ 150MPa, temperature 1450℃, holding time 3 hours, density ≥ 99%; Step 3: High temperature annealing stage, temperature control: 880℃, holding time: 2 hours / mm; After vacuum annealing, carbides are dispersed, improving the hardness of the matrix, and the hardness after annealing is ≤ 285HBW; Step 4: Quenching; Step 5: Tempering; Step 6: Isothermal treatment; Step 7: Cooling stage; Vacuum degree monitoring: Maintain vacuum degree < 1×10⁻³ Pa to prevent trace oxygen from causing abnormal precipitation of carbides; The quenching process in step 4 is pressure ≥ 150MPa , 1220℃, holding time 3 hours; the tempering process in step five is a furnace temperature of 560℃, and the final hardness can reach 70HRC; the isothermal treatment process in step six is ​​a temperature and time: 750℃, holding time 1~2 hours, which promotes the decomposition of austenite into pearlite and refines the structure; the cooling stage process in step seven is furnace cooling to 500℃ and then air cooling, or graded cooling is used, and it stays in a salt bath at 600~650℃ for 10~20 minutes.

[0021] In the processing of 5511 cast iron (HB320-340) deep hole drill bits manufactured by the drill bit component ratio of Example 2 in this embodiment, the cutting speed can reach 80-100m / min, which is 3 times more efficient than that of cemented carbide drill bits; tool durability: after processing 100 crankshafts, each containing 4 deep holes, it still remains sharp, and the cost is reduced by 60%. The drill bit of the present invention fundamentally solves the problems of rapid tool wear of traditional cemented carbide drill bits in deep hole processing of cast iron crankshafts, especially unstable surface quality on 5511 high-strength cast iron. At the same time, the high alloy element ratio ensures toughness and can cope with the high impact load of deep hole drilling. The drill bit material produced has high wear resistance and thermal stability.

[0022] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Within the scope of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

Claims

1. A powder high-speed steel deep hole drill with high hardness, wear resistance and toughness, characterized by: The drill bit matrix is ​​composed of C (1-3%), W (10-15%), Mo (2-5%), Cr (3-5%), Co (9-13%), V (3-6%) and 1.5-2.5% La2O3 nanoparticles, and is sintered to a density of ≥99% through hot isostatic pressing.

2. A powder high-speed steel deep hole drill with high hardness, wear resistance and toughness according to claim 1, characterized in that: The composite coating is a TiAlN / TiSiN multilayer structure with a layer thickness of 2-30 nm and a layer thickness ratio of TiAlN:TiSiN=1:

2.

3. A method for preparing a powder high-speed steel deep hole drill with high hardness, wear resistance and toughness according to claim 1, characterized in that: Step 1: Preheating stage, temperature range: 730~845℃, keep warm for 30~60 minutes to avoid thermal shock; Step 2: Hot isostatic pressing sintering process: pressure ≥ 150MPa, temperature 1350-1450℃, holding time 2-3 hours, density ≥ 99%; Step 3: High temperature annealing stage, temperature control: 850~880℃, holding time: 1~2 hours / mm; after vacuum annealing, carbides are dispersed, improving the hardness of the matrix, and the hardness after annealing is ≤285HBW; Step 4: Quenching; Step 5: Tempering; Step 6: Isothermal treatment; Step 7: Cooling stage.

4. The method for preparing a powder high-speed steel deep hole drill with high hardness, wear resistance and toughness according to claim 3, characterized in that: Vacuum degree monitoring: Maintain vacuum degree <1×10⁻³ Pa to prevent abnormal precipitation of carbides caused by trace oxygen.

5. The method for preparing a powder high-speed steel deep hole drill with high hardness, wear resistance and toughness according to claim 4, characterized in that: The quenching process in step 4 is a pressure ≥ 150 MPa, a temperature of 1180-1220°C, and a holding time of 2-3 hours.

6. The method for preparing a powder high-speed steel deep hole drill with high hardness, wear resistance and toughness according to claim 5, characterized in that: The tempering process in step five is carried out at a furnace temperature of 540-560°C, and the final hardness can reach 67-70HRC.

7. The method for preparing a powder high-speed steel deep hole drill with high hardness, wear resistance and toughness according to claim 6, characterized in that: The isothermal treatment process in step six is ​​as follows: temperature and time: 730~750℃, keeping warm for 1~2 hours, to promote the decomposition of austenite into pearlite and refine the structure.

8. The method for preparing a powder high-speed steel deep hole drill with high hardness, wear resistance and toughness according to claim 7, characterized in that: The cooling process in step seven is to cool the furnace to 500°C and then air cool, or adopt graded cooling and stay in a salt bath at 600~650°C for 10~20 minutes.