A high-strength composite hammer head and its manufacturing process

Abstract

The present invention relates to the technical field of metal materials. More specifically, it relates to a high-strength composite hammer head and its manufacturing process. The high-strength composite hammer head consists of a hammer head part and a hammer handle part. The chemical composition and mass fraction of the hammer head part are as follows: C: 3.0 - 3.8%, Si: 0.5 - 1.4%, Mn: 0.5 - 1.0%, Cr: 18.0 - 24.0%, Ni: 0.08 - 0.27%, Al: 0.08 - 0.19%, Ti: 0.01 - 0.06%, B: 0.01 - 0.03%, and the balance of Fe and inevitable impurity elements; the chemical composition and mass fraction of the hammer handle part are as follows: C: 0.2 - 0.6%, Si: 0.1 - 0.8%, Mn: 0.3 - 1.2%, Cr: 1.1 - 1.8%, Ni: 0.1 - 0.65%, Mo: 0.3 - 0.6%, and the balance of Fe and inevitable impurity elements. The manufacturing process steps of the high-strength composite hammer head of the present invention include: melting of the hammer head material, melting of the hammer handle material, composite casting and heat treatment processing.

Description

Technical Field

[0001] The present invention relates to the technical field of metal materials, and more specifically, it relates to a high-strength composite hammer head and its manufacturing process. Background Art

[0002] According to the actual use of the hammer head, different parts are usually required to have different mechanical properties. The hammer handle requires a certain strength and toughness, while the hammer head directly contacts the material, and the end part of the hammer head wears severely, so the end part is required to have strong wear resistance. The traditional single-material cast hammer head has high cost, large consumption, and it is difficult to meet the actual requirements in terms of strength, toughness, and wear resistance. Therefore, in order to meet the use requirements as much as possible, composite cast hammer head castings are usually made by composite casting process with multiple metals.

[0003] The main types of composite casting processes include liquid metal infiltration casting, centrifugal composite casting, bimetal casting, etc. Among them, the bimetal liquid-liquid composite casting process in bimetal casting refers to melting two metals simultaneously and pouring the two metal liquids into the mold according to the set pouring temperature, and metallurgical combination is generated around the interface after cooling. However, in the process of preparing a composite hammer head by using the bimetal liquid-liquid composite casting process, the materials of the two metal liquids usually have large differences in physical, chemical, and mechanical properties, resulting in problems such as high complexity of the process steps for composite pouring of the two metal liquids, difficult interface control, and metallurgical defects. It is difficult to accurately control parameters such as composite pouring and heat treatment processing of the two metal liquids, resulting in uneven distribution of intermetallic compounds or poor interface bonding at the bonding interface where the two different metal liquids come into contact, affecting the mechanical properties and wear resistance of the composite hammer head and reducing the manufacturing quality of the composite hammer head. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a high-strength composite hammer head and its manufacturing process.

[0005] A high-strength composite hammer head consists of a hammer head part and a hammer handle part;

[0006] The chemical composition and mass fraction of the hammer head part are: C: 3.0 - 3.8%, Si: 0.5 - 1.4%, Mn: 0.5 - 1.0%, Cr: 18.0 - 24.0%, Ni: 0.08 - 0.27%, Al: 0.08 - 0.19%, Ti: 0.01 - 0.06%, B: 0.01 - 0.03%, and the balance is Fe and inevitable impurity elements;

[0007] The chemical composition and mass fraction of the hammer handle part are as follows: C: 0.2 - 0.6%, Si: 0.1 - 0.8%, Mn: 0.3 - 1.2%, Cr: 1.1 - 1.8%, Ni: 0.1 - 0.65%, Mo: 0.3 - 0.6%, and the balance of Fe and inevitable impurity elements.

[0008] A manufacturing process for a high-strength composite hammer head includes the following steps:

[0009] S1: Melting of the hammer head material. According to the chemical composition requirements of the hammer head part (excluding Al, Ti, B), proportion the required hammer head materials, weigh the required hammer head materials, heat and melt them to obtain a high-chromium cast iron melt, add slag removal agent and inoculation modifier, and after inoculation modification, heat preservation and static settlement, and slag removal, obtain the melt for the hammer head.

[0010] The inoculation modifier is prepared by mixing AlTiB alloy and chromium nitride in a weight ratio of 1:(0.1 - 1). The chemical composition and mass fraction of the AlTiB alloy are as follows: Ti: 4.8 - 8.2%, B: 1.0 - 2.3%, and the balance of Al and inevitable impurity elements.

[0011] S2: Melting of the hammer handle material. According to the chemical composition requirements of the hammer handle part, proportion the required hammer handle materials, weigh the required hammer handle materials, heat and melt them to obtain a medium-carbon steel melt, and after heat preservation and static settlement, and slag removal, obtain the melt for the hammer handle.

[0012] S3: Composite casting and forming. First pour the melt for the hammer handle into the bottom of the hammer head model in the sand box, add an interface bonding assistant on the surface of the melt for the hammer handle in the hammer head model. After the melt for the hammer handle in the hammer head model naturally cools and solidifies for a period of time, pour the melt for the hammer head into the hammer head model until the riser on the sand box is filled with the melt for the hammer head, then stop pouring, remove the mixture of the melt for the hammer head and the interface bonding assistant at the riser, keep it warm under negative pressure for a period of time, then take it out of the box and air cool to obtain a composite hammer head casting.

[0013] S4: Heat treatment processing. After sand cleaning and grinding the composite hammer head casting, heat the composite hammer head casting to 630 - 650°C, keep it warm for 50 - 70 min, then continuously heat up to 1030 - 1050°C, keep it warm for 3 - 4 h. Subsequently, air cool the composite hammer head casting to 600 - 620°C, and then air cool to room temperature to complete the quenching treatment. At 430 - 450°C, keep it warm for 4 - 5 h to carry out the tempering treatment on the quenched composite hammer head casting. After the tempering is completed, air cool to room temperature to obtain a high-strength composite hammer head.

[0014] Furthermore, the hammer head materials include ordinary scrap steel, carburizer, ferrochrome, ferrosilicon, ferromanganese, nickel plate.

[0015] Further, the hammer handle material includes ordinary scrap steel, ferrochrome, ferrosilicon, ferromanganese, nickel plate, and ferromolybdenum.

[0016] Further, step S1: Melting of the hammer head material, specifically including the following steps:

[0017] S1.1: According to the chemical composition requirements of the hammer head material (excluding Al, Ti, B), weigh the required hammer head material, add the required hammer head material into Medium Frequency Induction Furnace Melting A, evacuate Medium Frequency Induction Furnace Melting A to below 150 Pa, and introduce argon into Medium Frequency Induction Furnace Melting A. Melt at 1480 - 1620 °C for 30 - 60 min to obtain a high chromium cast iron melt;

[0018] S1.2: Add a slag removing agent to the high chromium cast iron melt. The weight ratio of the high chromium cast iron melt to the slag removing agent is 1:(0.001 - 0.005), and refine the high chromium cast iron melt for 5 - 10 min;

[0019] S1.3: Add an inoculant and modifier to Ladle A, and quickly pour the refined high chromium cast iron melt into Ladle A by the pouring method. The weight ratio of the high chromium cast iron melt in Ladle A to the inoculant and modifier is 1:(0.004 - 0.01). Keep warm and stand still at 1420 - 1520 °C for 20 - 40 min, and remove slag to obtain the melt for the hammer head.

[0020] Further, the slag removing agent is at least one of sodium chloride, potassium chloride, calcium fluoride, aluminum trichloride, or alumina.

[0021] Further, step S2: Melting of the hammer handle material, specifically including the following steps:

[0022] S2.1: According to the chemical composition requirements of the hammer handle part, weigh the required hammer handle material, add the required hammer handle material into Medium Frequency Induction Furnace Melting B, evacuate Medium Frequency Induction Furnace Melting B to below 150 Pa, and introduce argon into Medium Frequency Induction Furnace Melting B. Melt at 1560 - 1620 °C for 30 - 60 min to obtain a medium carbon steel melt;

[0023] S2.2: Add a slag removing agent to the medium carbon steel melt. The weight ratio of the medium carbon steel melt to the slag removing agent is 1:(0.001 - 0.005), and refine the medium carbon steel melt for 5 - 10 min;

[0024] S2.3: Pour the refined medium carbon steel melt into Ladle B, keep warm and stand still at 1570 - 1620 °C for 20 - 60 min, and remove slag to obtain the melt for the hammer handle.

[0025] Further, step S3: Composite casting and forming, specifically including the following steps:

[0026] S3.1: Invert the hammer head model and place it in the sand box. Pour the melt of the hammer handle into the bottom of the hammer head model within 8 - 15 s. The pouring temperature is 1570 - 1600 °C. Subsequently, add an interfacial bonding aid on the surface of the melt of the hammer handle in the hammer head model. The addition amount of the interfacial bonding aid is 0.1 - 0.8% of the mass of the melt of the hammer handle in the hammer head model;

[0027] S3.2: After the melt of the hammer handle in the hammer head model naturally cools and solidifies for 120 - 180 s, pour the melt of the hammer head into the hammer head model from the riser of the sand box within 10 - 15 s until the riser is filled with the melt of the hammer head and then stop pouring. The pouring temperature is 1440 - 1460 °C. Since the interfacial bonding aid has a small specific gravity and density, the melt of the hammer head at the riser contains the floating interfacial bonding aid. Remove the mixture of the melt of the hammer head and the interfacial bonding aid at the riser to complete the pouring;

[0028] S3.3: After pouring is completed, keep it at a negative pressure of 0.03 - 0.05 MPa and heat - preserve for 6 - 8 h. Take out the obtained casting from the sand box and place it in the air to cool to obtain a composite hammer head casting.

[0029] Further, the interfacial bonding aid is prepared by mixing graphite powder and sodium borate according to a weight ratio of 1:(0.5 - 1.5).

[0030] Further, step S4: Heat treatment processing, specifically including the following steps:

[0031] S4.1: Clean and polish the composite hammer head casting. Subsequently, put the polished composite hammer head casting into a heating furnace and heat it up to 630 - 650 °C at a heating rate of 60 - 70 °C / h, keep it warm for 50 - 70 min. Then, continue to heat it up to 1030 - 1050 °C at a heating rate of 10 - 20 °C / min and keep it warm for 3 - 4 h;

[0032] S4.2: Subsequently, take out the composite hammer head casting from the heating furnace and air - cool it to 600 - 620 °C, then air - cool it to room temperature to complete the quenching treatment;

[0033] S4.3: Put the quenched composite hammer head casting into a heating furnace heated to 430 - 450 °C and keep it warm for 4 - 5 h for tempering treatment;

[0034] S4.4: After tempering is completed, air - cool it to room temperature, take out the tempered composite hammer head casting from the heating furnace to obtain a high - strength composite hammer head.

[0035] The present invention has the following advantages:

[0036] 1. In the present invention, the inoculant modifier has a combined effect of modification and refinement on the high-chromium cast iron melt. Under the synergistic action of chromium nitride and AlTiB alloy, compounds such as AlCr, TiB2, and TiC formed can serve as heterogeneous nucleation cores during the solidification of high-chromium cast iron at high temperatures, promoting the refinement of grains and carbides, hindering the growth of carbides, achieving a significant grain refinement effect, forming a fine microstructure, and being beneficial to improving the strength and wear resistance of the hammer head material.

[0037] 2. In the present invention, a composite hammer head casting is obtained by casting the melt for the hammer handle and the melt for the hammer head. During the casting process, after the melt for the hammer handle is poured into the hammer head mold to form the hammer handle part, by adding an interfacial bonding aid, a layer of interfacial bonding aid covers the surface layer of the melt for the hammer handle. The sodium borate component in the interfacial bonding aid has the characteristics of low melting point, low density, low viscosity, and low surface tension, which can provide good lubricity to the surface layer of the melt for the hammer handle, being beneficial to reducing the generation of oxides and improving the cleanliness of the surface of the melt for the hammer handle. And the graphite powder component in the interfacial bonding aid can effectively reduce the oxides formed on the surface of the melt for the hammer handle, generate gases insoluble in the molten metal, and discharge them outside the hammer head mold, effectively ensuring the metallurgical diffusion bonding between the subsequent melt for the hammer head and the melt for the hammer handle after pouring into the hammer head mold, improving the interfacial bonding strength of the composite hammer head casting, reducing fracture or detachment at the interface, and enhancing the overall performance of the composite hammer head.

[0038] 3. During the heat treatment process of the composite hammer head casting in the present invention, quenching treatment is first carried out and then tempering treatment. In the quenching treatment, first, it is heated at a slow heating rate of 60 - 70 °C / h to 630 - 650 °C for holding to carry out low-temperature primary quenching treatment, which can effectively eliminate the internal stress caused by the surface and core temperature gradient of the composite hammer head casting, thereby reducing the occurrence of deformation and cracking of the composite hammer head. Furthermore, then it is continuously heated at a heating rate of 10 - 20 °C / min to 1030 - 1050 °C for holding to carry out high-temperature secondary quenching treatment. Through the cooperation of high- and low-temperature secondary quenching treatments, the wear resistance and impact toughness of the high-strength composite hammer head are effectively enhanced; in the tempering treatment, rapid heating and tempering can eliminate the internal stress generated in the composite hammer head casting during quenching, making the hammer handle part of the high-strength composite hammer head composed of bainite and tempered troostite, and the hammer head part composed of long strip martensite, ledeburite, and a small amount of pearlite. Among them, the long strip martensite in the hammer head part can serve as a matrix to provide support for the carbides in the hammer head part, making the carbides distributed in a strip shape and scattered, effectively enhancing the hardness and wear resistance of the high-strength composite hammer head. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a process flow chart of a manufacturing process for a high-strength composite hammer head adopted in an embodiment of the present invention.

[0040] Figure 2 This is a microhardness variation diagram of the interface transition region of the high-strength composite hammer head in the embodiment of the present invention and Comparative Example 4. Specific Embodiments

[0041] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0042] Embodiment 1

[0043] A manufacturing process of a high-strength composite hammer head, as Figure 1 shown, specifically includes the following steps:

[0044] S1: Melting of the hammer head material,

[0045] S1.1: According to the following chemical composition and mass fraction: C: 3.2%, Si: 0.8%, Mn: 0.8%, Cr: 21.0%, Ni: 0.15%, and the balance of Fe and inevitable impurity elements, weigh the required ordinary scrap steel, carburant, ferrochrome, ferrosilicon, ferromanganese and nickel plate as the hammer head material, add the hammer head material to the medium-frequency induction furnace A for melting, evacuate the medium-frequency induction furnace A to below 150 Pa, and, introduce argon gas into the medium-frequency induction furnace A, melt at 1620 °C for 60 min to obtain a high-chromium cast iron melt;

[0046] S1.2: Add potassium chloride to the high-chromium cast iron melt, and the weight ratio of the high-chromium cast iron melt to potassium chloride is 1:0.005, and refine the high-chromium cast iron melt for 10 min;

[0047] S1.3: Add an inoculant and modifier to the ladle A, quickly pour the refined high-chromium cast iron melt into the ladle A, and the weight ratio of the high-chromium cast iron melt in the ladle A to the inoculant and modifier is 1:0.01, keep warm and stand still at 1520 °C for 40 min, remove slag to obtain the melt for the hammer head;

[0048] Among them, the preparation steps of the inoculant and modifier are: add the AlTiB alloy to a crusher, crush the AlTiB alloy into particles with a particle size of 3 mm to obtain alloy particles, stir and mix the alloy particles and chromium nitride powder according to a weight ratio of 1:0.8 to obtain the inoculant and modifier, wherein the chemical composition and mass fraction of the AlTiB alloy are: Ti: 6.5%, B: 1.8%, and the balance of Al and inevitable impurity elements;

[0049] S2: Melting of the hammer handle material,

[0050] S2.1: Mix according to the chemical composition requirements of the hammer handle part. The chemical composition and mass fraction of the hammer handle part are as follows: C: 0.6%, Si: 0.3%, Mn: 0.8%, Cr: 1.3%, Ni: 0.15%, Mo: 0.5%, and the balance is Fe and inevitable impurity elements. Weigh the required ordinary scrap steel, ferrochrome, ferrosilicon, ferromanganese, nickel plate and ferromolybdenum as the hammer handle material, add the hammer handle material to the intermediate frequency induction furnace B for melting. The intermediate frequency induction evacuates the furnace B for melting to below 150 Pa, and argon is introduced into the intermediate frequency induction furnace B for melting. It is melted at 1620 °C for 60 min to obtain medium carbon steel melt;

[0051] S2.2: Add potassium chloride to the medium carbon steel melt. The weight ratio of the medium carbon steel melt to potassium chloride is 1:0.005, and the medium carbon steel melt is refined for 10 min;

[0052] S2.3: Pour the refined medium carbon steel melt into ladle B, keep it warm and static at 1620 °C for 60 min, remove the slag to obtain the melt for the hammer handle;

[0053] S3: Composite casting

[0054] S3.1: The hammer head model in the sand box is in an inverted state. Pour the melt for the hammer handle into the bottom of the hammer head model within 15 s. The pouring temperature is 1600 °C. Subsequently, add an interface bonding assistant to the surface of the melt for the hammer handle in the hammer head model to protect the surface of the melt for the hammer handle in the hammer head model from oxidation. The addition amount of the interface bonding assistant is 0.3% of the mass of the melt for the hammer handle in the hammer head model. The interface bonding assistant is prepared by mixing graphite powder and sodium borate according to a weight ratio of 1:1;

[0055] S3.2: After the melt for the hammer handle in the hammer head model naturally cools and solidifies for 180 s, pour the melt for the hammer head into the hammer head model from the riser of the sand box within 15 s until the riser is full of the melt for the hammer head and stop pouring. The pouring temperature is 1460 °C. Since the interface bonding assistant has a small specific gravity and density, the melt for the hammer head at the riser contains the interface bonding assistant added to the hammer head model and floating up. Then, remove the mixture of the melt for the hammer head and the interface bonding assistant at the riser to complete the pouring;

[0056] S3.3: After pouring is completed, keep it warm for 8 h under a negative pressure of 0.05 MPa. Take the obtained casting out of the box and place it in the air to cool to obtain a composite hammer head casting;

[0057] S4: Heat treatment

[0058] S4.1: Remove the sand and polish the composite hammerhead casting. Then, place the polished composite hammerhead casting into a heating furnace and heat it up to 650°C at a rate of 60°C / h, hold for 60 min. Then, continue to heat it up to 1050°C at a heating rate of 20°C / min and hold for 4 h;

[0059] S4.2: Then, take out the composite hammerhead casting from the heating furnace, air-cool it to 620°C, and then air-cool it to room temperature to complete the quenching treatment;

[0060] S4.3: Place the quenched composite hammerhead casting into a heating furnace heated to 450°C and hold for 5 h for tempering treatment to eliminate the internal stress generated during quenching;

[0061] S4.4: After tempering, air-cool it to room temperature, take out the tempered composite hammerhead casting from the heating furnace to obtain a high-strength composite hammerhead.

[0062] Example 2

[0063] A manufacturing process for a high-strength composite hammerhead, as Figure 1 shown, specifically includes the following steps:

[0064] S1: Melting of the hammerhead material,

[0065] S1.1: According to the following chemical composition and mass fraction: C: 3.2%, Si: 0.8%, Mn: 0.8%, Cr: 21.0%, Ni: 0.15% and the balance of Fe and inevitable impurity elements, weigh the required ordinary scrap steel, carburizer, ferrochrome, ferrosilicon, ferromanganese and nickel plate as the hammerhead material, add the hammerhead material to Medium Frequency Induction Furnace Melting A, evacuate Medium Frequency Induction Furnace Melting A to below 150 Pa, and, introduce argon into Medium Frequency Induction Furnace Melting A, melt at 1540°C for 30 min to obtain a high-chromium cast iron melt;

[0066] S1.2: Add potassium chloride to the high-chromium cast iron melt, the weight ratio of the high-chromium cast iron melt to potassium chloride is 1:0.005, and refine the high-chromium cast iron melt for 5 min;

[0067] S1.3: Add an inoculant and modifier to Ladle A, quickly pour the refined high-chromium cast iron melt into Ladle A, the weight ratio of the high-chromium cast iron melt in Ladle A to the inoculant and modifier is 1:0.01, hold and stand at 1420°C for 20 min, remove the slag to obtain the melt for the hammerhead;

[0068] Among them, the preparation steps of the inoculant modifier are as follows: Add the AlTiB alloy to a crusher, crush the AlTiB alloy into particles with a particle size of 3 mm to obtain alloy particles, and stir and mix the alloy particles with chromium nitride powder according to a weight ratio of 1:0.8 to obtain the inoculant modifier. The chemical composition and mass fraction of the AlTiB alloy are: Ti: 6.5%, B: 1.8%, and the balance of Al and inevitable impurity elements;

[0069] S2: Melting of the hammer handle material,

[0070] S2.1: Make a ratio according to the chemical composition requirements of the hammer handle part. The chemical composition and mass fraction of the hammer handle part are: C: 0.6%, Si: 0.3%, Mn: 0.8%, Cr: 1.3%, Ni: 0.15%, Mo: 0.5%, and the balance of Fe and inevitable impurity elements. Weigh the required ordinary scrap steel, ferrochrome, ferrosilicon, ferromanganese, nickel plate and ferromolybdenum as the hammer handle material, and add the hammer handle material to the intermediate frequency induction furnace B for melting. The intermediate frequency induction evacuates the furnace B to below 150 Pa, and furthermore, argon is introduced into the intermediate frequency induction furnace B, and it is melted at 1560 °C for 30 min to obtain medium carbon steel melt;

[0071] S2.2: Add potassium chloride to the medium carbon steel melt. The weight ratio of the medium carbon steel melt to potassium chloride is 1:0.005, and the medium carbon steel melt is refined for 5 min;

[0072] S2.3: Pour the refined medium carbon steel melt into ladle B, keep it warm and static at 1570 °C for 20 min, remove the slag to obtain the melt for the hammer handle;

[0073] S3: Composite casting and forming,

[0074] S3.1: The hammer head model in the sand box is in an inverted state. Pour the melt for the hammer handle into the bottom of the hammer head model within 8 s. The pouring temperature is 1570 °C. Subsequently, add an interface bonding aid to the surface of the melt for the hammer handle in the hammer head model to protect the surface of the melt for the hammer handle in the hammer head model against oxidation. The addition amount of the interface bonding aid is 0.3% of the mass of the melt for the hammer handle in the hammer head model. The interface bonding aid is prepared by mixing graphite powder and sodium borate according to a weight ratio of 1:1;

[0075] S3.2: After the melt for the hammer handle in the hammer head model naturally cools and solidifies for 120 s, pour the melt for the hammer head into the hammer head model from the riser of the sand box within 10 s until the riser is filled with the melt for the hammer head and then stop pouring. The pouring temperature is 1440 °C. Since the interface bonding aid has a small specific gravity and density, the melt for the hammer head at the riser contains the interface bonding aid added to the hammer head model and floating on it. Then, remove the mixture of the melt for the hammer head and the interface bonding aid at the riser to complete the pouring;

[0076] After the pouring in S3.3 is completed, under a negative pressure of 0.03 MPa, keep it warm for 6 h, take out the obtained casting from the mold and place it in the air to cool, thus obtaining a composite hammerhead casting;

[0077] S4: Heat treatment processing,

[0078] S4.1: Carry out sand cleaning and grinding on the composite hammerhead casting. Subsequently, put the ground composite hammerhead casting into a heating furnace, heat it up to 630 °C at a rate of 70 °C / h, keep it warm for 50 min. Then, continue to heat it up to 1030 °C at a heating rate of 10 °C / min and keep it warm for 3 h;

[0079] S4.2: Subsequently, take out the composite hammerhead casting from the heating furnace, air-cool it to 600 °C, and then air-cool it to room temperature to complete the quenching treatment;

[0080] S4.3: Put the quenched composite hammerhead casting into a heating furnace heated to 430 °C, keep it warm for 4 h for tempering treatment to eliminate the internal stress generated during quenching;

[0081] S4.4: After the tempering is completed, air-cool it to room temperature, take out the tempered composite hammerhead casting from the heating furnace to obtain a high-strength composite hammerhead.

[0082] Example 3

[0083] A manufacturing process of a high-strength composite hammerhead, as Figure 1 shown, specifically includes the following steps:

[0084] S1: Melting of the hammerhead material,

[0085] S1.1: According to the following chemical composition and mass fraction: C: 3.6%, Si: 1.2%, Mn: 0.5%, Cr: 18.0%, Ni: 0.1%, and the balance of Fe and inevitable impurity elements, weigh the required ordinary scrap steel, carburizer, ferrochrome, ferrosilicon, ferromanganese and nickel plate as the hammerhead material, add the hammerhead material into Medium Frequency Induction Furnace Melting A, evacuate Medium Frequency Induction Furnace Melting A to below 150 Pa, and, introduce argon into Medium Frequency Induction Furnace Melting A, melt at 1620 °C for 60 min to obtain a high-chromium cast iron melt;

[0086] S1.2: Add potassium chloride to the high-chromium cast iron melt, and the weight ratio of the high-chromium cast iron melt to potassium chloride is 1:0.002, and refine the high-chromium cast iron melt for 10 min;

[0087] S1.3: Add inoculant and modifier into ladle A, quickly pour the refined high-chromium cast iron melt into ladle A. The weight ratio of the high-chromium cast iron melt in ladle A to the inoculant and modifier is 1:0.004. Keep it warm and static for 40 min at 1520 °C, remove the slag, and obtain the melt for the hammer head.

[0088] Among them, the preparation steps of the inoculant and modifier are as follows: Add AlTiB alloy into a crusher, crush the AlTiB alloy into particles with a particle size of 3 mm to obtain alloy particles, stir and mix the alloy particles and chromium nitride powder according to a weight ratio of 1:1 to obtain the inoculant and modifier. The chemical composition and mass fraction of the AlTiB alloy are: Ti: 4.8%, B: 1.4%, and the balance Al and inevitable impurity elements.

[0089] S2: Melting of the hammer handle material

[0090] S2.1: Make the proportion according to the chemical composition requirements of the hammer handle part. The chemical composition and mass fraction of the hammer handle part are: C: 0.3%, Si: 0.5%, Mn: 1.1%, Cr: 1.5%, Ni: 0.33%, Mo: 0.3%, and the balance Fe and inevitable impurity elements. Weigh the required ordinary scrap steel, ferrochromium, ferrosilicon, ferromanganese, nickel plate and ferromolybdenum as the hammer handle material, add the hammer handle material into medium-frequency induction furnace B for melting. The medium-frequency induction furnace B is evacuated to below 150 Pa, and argon is introduced into the medium-frequency induction furnace B. Melt at 1620 °C for 60 min to obtain medium-carbon steel melt.

[0091] S2.2: Add potassium chloride into the medium-carbon steel melt. The weight ratio of the medium-carbon steel melt to potassium chloride is 1:0.002, and refine the medium-carbon steel melt for 10 min.

[0092] S2.3: Pour the refined medium-carbon steel melt into ladle B, keep it warm and static for 60 min at 1620 °C, remove the slag, and obtain the melt for the hammer handle.

[0093] S3: Composite casting

[0094] S3.1: The hammer head model in the sand box is in an inverted state. Pour the melt for the hammer handle into the bottom of the hammer head model within 15 s. The pouring temperature is 1600 °C. Subsequently, add an interfacial bonding aid on the surface of the melt for the hammer handle in the hammer head model to play an anti-oxidation protection role on the surface of the melt for the hammer handle in the hammer head model. The addition amount of the interfacial bonding aid is 0.6% of the mass of the melt for the hammer handle in the hammer head model. The interfacial bonding aid is prepared by mixing graphite powder and sodium borate according to a weight ratio of 1:0.5.

[0095] S3.2 After the hammer handle in the hammer head model is naturally cooled and solidified by the melt for 180 s, the melt for the hammer head is poured into the hammer head model from the riser of the sand box within 15 s until the riser is filled with the melt for the hammer head, and the pouring is stopped. The pouring temperature is 1460 °C. Since the interface bonding additive has a small specific gravity and density, the melt for the hammer head at the riser contains the interface bonding additive added to the hammer head model and floating upward. Then, the mixture of the melt for the hammer head and the interface bonding additive at the riser is removed to complete the pouring;

[0096] S3.3 After the pouring is completed, under a negative pressure of 0.05 MPa, keep warm for 8 h, take out the obtained casting from the sand box and place it in the air to cool to obtain a composite hammer head casting;

[0097] S4: Heat treatment processing,

[0098] S4.1: Clean and grind the composite hammer head casting. Then, put the ground composite hammer head casting into a heating furnace, heat it up to 650 °C at a rate of 60 °C / h, keep warm for 60 min, and then continue to heat it up to 1050 °C at a heating rate of 20 °C / min and keep warm for 4 h;

[0099] S4.2: Then, take out the composite hammer head casting from the heating furnace, air-cool it to 620 °C, and then air-cool it to room temperature to complete the quenching treatment;

[0100] S4.3: Put the quenched composite hammer head casting into a heating furnace heated to 450 °C, keep warm for 5 h for tempering treatment to eliminate the internal stress generated during quenching;

[0101] S4.4: After the tempering is completed, air-cool it to room temperature, take out the tempered composite hammer head casting from the heating furnace to obtain a high-strength composite hammer head.

[0102] Comparative Example 1

[0103] Compared with Example 1, the difference in Comparative Example 1 is that the addition operation of the inoculant modifier in step S1.3 is removed. After the refining is completed, the refined high-chromium cast iron melt is directly poured into ladle A, kept warm and static at 1520 °C for 40 min, and the slag is removed to obtain the melt for the hammer head. The remaining steps remain unchanged to prepare a high-strength composite hammer head, denoted as Comparative Example 1.

[0104] Comparative Example 2

[0105] Compared with Example 1, the difference in Comparative Example 2 is that the inoculant modifier in step S1.3 consists only of chromium nitride, and the remaining steps remain unchanged to prepare a high-strength composite hammer head, denoted as Comparative Example 2.

[0106] Comparative Example 3

[0107] Compared with Example 1, the difference in Comparative Example 3 is that the inoculant modifier in step S1.3 consists only of AlTiB alloy, and the remaining steps remain unchanged. A high-strength composite hammer head is prepared, denoted as Comparative Example 3.

[0108] Comparative Example 4

[0109] Compared with Example 1, the difference in Comparative Example 4 is that the step of adding the interfacial bonding aid in step S3.1 is removed. After injecting the melt of the hammer handle into the hammer head mold, the melt of the hammer handle part in the hammer head mold is directly allowed to cool and solidify naturally, and the remaining steps remain unchanged. A high-strength composite hammer head is prepared, denoted as Comparative Example 4.

[0110] Comparative Example 5

[0111] Compared with Example 1, the difference in Comparative Example 5 is that in step S4.1, after the polished composite hammer head casting is placed in the heating furnace, it is directly heated to 1050 °C at a heating rate of 20 °C / min and held for 4 h, and the remaining steps remain unchanged. A high-strength composite hammer head is prepared, denoted as Comparative Example 5.

[0112] Comparative Example 6

[0113] Compared with Example 1, the difference in Comparative Example 6 is that steps S4.3 - S4.4 are removed. After the quenching treatment is completed, a high-strength composite hammer head is obtained, and the remaining steps remain unchanged, denoted as Comparative Example 6.

[0114] Wear resistance test

[0115] According to the national standard GB / T12444-2006, the friction and wear performance of the hammer head part of the high-strength composite hammer heads in Examples 1 - 3 and Comparative Examples 1 - 6 was detected using an M-2000 abrasive wear testing machine. The load was 200 N, the test time was 2 h, and the rotation speed was 200 rad / min. The weights of the high-strength composite hammer heads before and after wear were weighed and recorded, and the wear rate was calculated. Among them, the wear rate calculation formula is: S0 and S1 are the weights of the high-strength composite hammer head before and after wear, respectively. The test results of the wear resistance are shown in Table 1.

[0116] Table 1:

[0117] Group Wear rate (%) Example 1 0.76 Example 2 0.91 Example 3 0.88 Comparative Example 1 1.67 Comparative Example 2 1.26 Comparative Example 3 1.51 Comparative Example 4 1.05 Comparative Example 5 1.82 Comparative Example 6 1.59

[0118] As shown in Table 1, after the wear test of the high-strength composite hammer heads of Examples 1-3, their wear rates are all less than 1%, and the wear results are better than those of Comparative Examples 1-6, having good wear resistance. It shows that during the melting process of the hammer head material, inoculation modification treatment of the melt for the hammer head by using an inoculant prepared by mixing AlTiB alloy and chromium nitride can effectively improve the wear resistance of the hammer head material. The AlTiB alloy and chromium nitride in the inoculant cooperate with each other during the inoculation modification treatment, which can promote the refinement of grains and carbides in the melt for the hammer head, forming a fine microstructure. Moreover, during the heat treatment process of the composite hammer head casting, before high-temperature quenching, a high-low temperature secondary quenching process of heating up to 630-650°C at a slow heating rate of 60-70°C / h for low-temperature quenching and tempering treatment cooperate with each other, which can have a significant impact on the wear resistance of the high-strength composite hammer head.

[0119] Mechanical property test

[0120] In accordance with the national standard GB / T3808-2002, a pendulum impact testing machine was used to detect the impact strength of the high-strength composite hammer heads in Examples 1-3 and Comparative Examples 1-6; in accordance with the standard GB / T24186-2009, the tensile strength and hardness of the high-strength composite hammer heads in Examples 1-3 and Comparative Examples 1-6 were detected. The test results of the mechanical properties are shown in Table 2.

[0121] Table 2:

[0122]

[0123] As shown in Table 2, for the high-strength composite hammer heads of Examples 1-3, the results of the impact toughness, tensile strength and hardness of the hammer head part and the hammer handle part are better than those of the high-strength composite hammer heads of Comparative Examples 1-5. It shows that during the preparation process of the high-strength composite hammer head, the inoculation modification treatment of the inoculant, the addition and use of the interface bonding aid, and the heat treatment processing technology within a specific temperature range can all improve the hardness and toughness of the high-strength composite hammer head, which is beneficial to enhancing the mechanical properties of the high-strength composite hammer head.

[0124] Interface bonding detection

[0125] Samples were taken from the interface transition region of the high-strength composite hammer heads of Examples 1-3 and Comparative Example 4 through wire cutting process. After sampling, the samples were processed into block specimens, and a microhardness tester was used to measure the micro-Vickers hardness at different positions of the block specimens. Five points were measured at each part, and the average value was taken as the test result. The results are as Figure 2 shown.

[0126] As Figure 2It can be seen that in Examples 1-3, the microhardness of the interface of the high-strength composite hammer head is greater, and the microhardness transition in the interface transition region is more gentle and uniform. This shows that the addition of the interface bonding additive not only improves the hardness of the high-strength composite hammer head, especially the hardness of the hammer handle part, but also helps to ease the hardness change in the transition region between the hammer head part and the hammer handle part, playing a strengthening role for the high-strength composite hammer head.

[0127] It should be understood that those of ordinary skill in the art can make improvements or transformations according to the above description, and all such improvements and transformations should fall within the protection scope of the appended claims of the present invention. The parts not described in detail in this specification belong to the well-known prior art of those skilled in the art.

Claims

1. A high-strength composite hammer head, characterized in that: It consists of a hammer head and a hammer handle: The chemical composition and mass fraction of the hammer head are: C: 3.0-3.8%, Si: 0.5-1.4%, Mn: 0.5-1.0%, Cr: 18.0-24.0%, Ni: 0.08-0.27%, Al: 0.08-0.19%, Ti: 0.01-0.06%, B: 0.01-0.03% and the balance of Fe and unavoidable impurity elements; The chemical composition and mass fraction of the hammer handle are: C: 0.2-0.6%, Si: 0.1-0.8%, Mn: 0.3-1.2%, Cr: 1.1-1.8%, Ni: 0.1-0.65%, Mo: 0.3-0.6% and the balance of Fe and unavoidable impurity elements; A manufacturing process of a high-strength composite hammer head comprises the following steps: S1: Melting of hammer material: according to the requirements of the chemical composition of the hammer material, except Al, Ti, and B, the required hammer material is weighed, the required hammer material is heated and melted to obtain a high-chromium cast iron melt, a slag remover and an inoculating and modifying agent are added, and after inoculating and modifying, heat-insulating and standing, and slag removal, a melt for the hammer is obtained; The inoculated modifier is prepared by mixing AlTiB alloy and chromium nitride in a weight ratio of 1:(0.1-1), and the chemical composition and mass fraction of the AlTiB alloy are: Ti: 4.8-8.2%, B: 1.0-2.3% and the balance of Al and inevitable impurity elements; S2: Melting of hammer handle materials: weighing the required hammer handle materials according to the chemical composition requirements of the hammer handle part, heating and melting the required hammer handle materials to obtain medium carbon steel melt, and then heat-insulating, standing and removing slag to obtain a melt for the hammer handle; S3: composite casting molding, first pouring the melt for the hammer handle into the bottom of the hammer head model in the sand box, adding an interface bonding agent on the surface of the melt for the hammer handle in the hammer head model, and after the melt for the hammer handle in the hammer head model is naturally cooled and solidified for a period of time, pouring the melt for the hammer head into the hammer head model until the riser on the sand box is filled with the melt for the hammer head, and then stopping the pouring, removing the mixture of the melt for the hammer head and the interface bonding agent at the riser, and keeping the temperature under negative pressure for a period of time, taking it out of the box, and air cooling it to obtain a composite hammer head casting; S4: Heat treatment processing, specifically including the following steps: S4.1: The composite hammer casting is sanded and polished, and then the polished composite hammer casting is placed in a heating furnace, heated to 630-650°C at a heating rate of 60-70°C / h, and kept warm for 50-70 min, and then continuously heated to 1030-1050°C at a heating rate of 10-20°C / min, and kept warm for 3-4 h; S4.2: Then, the composite hammer casting is taken out from the heating furnace, air-cooled to 600-620°C, and then air-cooled to room temperature to complete the quenching treatment; S4.3: Place the quenched composite hammer casting into a heating furnace heated to 430-450°C and keep it at this temperature for 4-5 hours for tempering treatment; S4.4: After tempering, air cool to room temperature, take out the tempered composite hammer casting from the heating furnace, and obtain a high-strength composite hammer.

2. A high-strength composite hammer head according to claim 1, characterized in that: Hammer head materials include ordinary scrap steel, carburizer, ferrochrome, ferrosilicon, ferromanganese and nickel plate.

3. A high-strength composite hammer head according to claim 2, characterized in that: The hammer handle materials include ordinary scrap steel, ferrochrome, ferrosilicon, ferromanganese, nickel plate and ferromolybdenum.

4. A high-strength composite hammer head according to claim 1, characterized in that: Step S1: Melting of hammer material, specifically including the following steps: S1.1: According to the requirements of the chemical composition of the hammer material, except Al, Ti, and B, the required hammer material is weighed, and the required hammer material is added to the medium frequency induction furnace smelting A, and the medium frequency induction furnace smelting A is evacuated to below 150Pa, and argon is introduced into the medium frequency induction furnace smelting A, and smelting is carried out at 1480-1620°C for 30-60min to obtain a high chromium cast iron melt; S1.2: adding a slag remover to the high chromium cast iron melt, wherein the weight ratio of the high chromium cast iron melt to the slag remover is 1:(0.001-0.005), and refining the high chromium cast iron melt for 5-10 minutes; S1.3: Add inoculant to ladle A, and quickly inject the refined high chromium cast iron melt into ladle A by injection method. The weight ratio of high chromium cast iron melt to inoculant in ladle A is 1: (0.004-0.01). Keep it at 1420-1520℃ for 20-40min, remove the slag, and obtain the melt for hammer.

5. A high-strength composite hammer head according to claim 4, characterized in that: The slag remover is at least one of sodium chloride, potassium chloride, calcium fluoride, aluminum chloride or aluminum oxide.

6. A high-strength composite hammer head according to claim 1, characterized in that: Step S2: Melting of hammer handle material, specifically including the following steps: S2.1: According to the requirements of the chemical composition of the hammer handle part, the required hammer handle material is weighed and added to the medium frequency induction furnace smelting B. The medium frequency induction furnace smelting B is evacuated to below 150Pa, and argon is introduced into the medium frequency induction furnace smelting B. The smelting is carried out at 1560-1620°C for 30-60min to obtain a medium carbon steel melt; S2.2: add a slag remover to the medium carbon steel melt, the weight ratio of the medium carbon steel melt to the slag remover is 1: (0.001-0.005), and refine the medium carbon steel melt for 5-10 minutes; S2.3: Pour the refined medium carbon steel melt into ladle B, keep it at 1570-1620℃ for 20-60min, remove the slag, and obtain the melt for hammer handle.

7. A high-strength composite hammer head according to claim 1, characterized in that: Step S3: composite casting, specifically comprising the following steps: S3.1: Place the hammer head model upside down in the sand box, pour the hammer handle melt into the bottom of the hammer head model within 8 to 15 seconds, and the pouring temperature is 1570 to 1600°C. Then, add an interface bonding additive to the surface of the hammer handle melt in the hammer head model, and the amount of the interface bonding additive added is 0.1 to 0.8% of the mass of the hammer handle melt in the hammer head model; S3.2 After the molten hammer handle in the hammer head model is naturally cooled and solidified for 120 to 180 seconds, the molten hammer head is poured into the hammer head model from the riser of the sand box within 10 to 15 seconds until the riser is filled with the molten hammer head. The pouring temperature is 1440 to 1460°C. Since the interface bonding additive has a small specific gravity and a small density, the molten hammer head at the riser contains the floating interface bonding additive. The mixture of the molten hammer head and the interface bonding additive at the riser is removed to complete the pouring; S3.3 After the pouring is completed, the casting is kept warm for 6 to 8 hours under a negative pressure of 0.03 to 0.05 MPa, and the obtained casting is taken out of the box and placed in the air to cool to obtain a composite hammer head casting.

8. A high-strength composite hammer head according to claim 7, characterized in that: The interface bonding aid is prepared by mixing graphite powder and sodium borate in a weight ratio of 1: (0.5-1.5).

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