A high hard tough quenched-carbon partition wear-resistant steel and a preparation method thereof

Abstract

The present application relates to wear-resistant steel, more particularly to a high-hard-tough quenched-carbon partition wear-resistant steel and a preparation method thereof. The present application is aimed at the low hardness-toughness matching and high production cost of the existing metal material under the medium stress impact abrasive wear working condition, and the low alloy steel mainly composed of martensite and supplemented with a certain amount of metastable residual austenite is obtained by optimizing the alloy composition and adopting the process of isothermal quenching at the martensite transformation temperature (Ms), and the low alloy steel is simple and easy to control, such as smelting, casting forming, normalizing, isothermal quenching and tempering, and is low in cost and beneficial to popularization. The low alloy steel has good toughness matching while maintaining high hardness, and is suitable for the preparation of wear-resistant parts under the medium stress impact abrasive wear working condition.

Description

Technical Field

[0001] This invention relates to wear-resistant steel, and more specifically to a high-hardness and high-toughness quenched-carbon-partitioned wear-resistant steel and its preparation method. Background Technology

[0002] Depending on the magnitude of the stress on the abrasive grains, abrasive wear can be classified into gouging abrasive wear, high-stress crushing abrasive wear, medium-stress impact abrasive wear, and low-stress scuffing wear. Medium-stress impact abrasive wear is prevalent in metallurgy, mining, power, agriculture, chemical, building materials, and machinery industries, such as ball mill liners and impact crusher liners. The cement industry alone consumes millions of tons of ball mill liners annually. Therefore, researching and developing wear-resistant steels suitable for medium-stress impact abrasive wear conditions has significant economic and social implications. Given that increasing the hardness of the material can weaken the micro-cutting behavior of the abrasive, thereby improving its wear resistance, early research on wear-resistant steels under medium-stress impact abrasive wear conditions mainly focused on increasing the hardness of the material, developing high-chromium cast iron and low-alloy martensitic steel. However, with the deepening research into the failure mechanism of components under medium-stress impact abrasive wear conditions, appropriately increasing the toughness of the material can not only improve its wear resistance but also enhance the overload resistance of the components and reduce premature fracture failure. Matching the hardness and toughness of materials under moderate stress impact abrasive wear conditions has become a key focus and hot topic in the field of wear-resistant materials research.

[0003] Chinese patent CN113265580A discloses a high-nitrogen, high-vanadium, and high-chromium wear-resistant alloy and its preparation method. Utilizing primary volatile organic compounds (VC) as the eutectic nucleation core, the size of M7C3 type carbides and the austenite dendrite arm spacing are reduced to prepare a high-nitrogen, high-vanadium, and high-chromium alloy with a hardness of 62.2-63.5 HRC and an impact toughness of 8.6-10.6 J / cm². Compared with traditional high-chromium cast iron (56.5 HRC, 5.25 J / cm²), the hardness is increased by approximately 10.1%-12.4%, and the impact toughness is increased by 63.8%-100.1%. Although the impact toughness is significantly improved, the absolute value of the impact toughness is still relatively low, and the addition of a large amount of vanadium further increases the production cost, which is not conducive to its widespread application in practical engineering.

[0004] Chinese patent CN105856725A discloses a bimetallic bainitic-martensitic multiphase wear-resistant liner and its preparation method. A bimetallic layered casting process is employed, followed by conventional salt bath isothermal quenching heat treatment, to obtain a composite liner with an inner layer hardness of 55-57 HRC and an impact toughness of 11-14 J / cm², and an outer layer hardness of 45-50 HRC and an impact toughness of 19-21 J / cm², achieving an excellent balance between hardness and toughness. However, the production process of this composite liner is complex and costly. Furthermore, the junction between the porous matrix and the insert is prone to cracking and premature fracture under material impact, making it difficult to guarantee the safety of the bimetallic liner in use.

[0005] Chinese patent CN105856725A discloses a high-wear-resistant martensitic / austenitic duplex wear-resistant steel plate and its manufacturing method. This steel employs two-phase annealing to introduce a certain amount of retained austenite, ensuring the material's toughness, while simultaneously controlling the precipitation of a certain amount of ultra-hard (Ti,Mo)C particles to guarantee the material's strength. The resulting martensitic / austenitic duplex wear-resistant steel exhibits a tensile strength of 1000-1200 MPa, an elongation of 13%-20%, an impact energy greater than 40 J at -20℃, and a hardness of 360-450 HB. However, the production process of this duplex steel involves smelting, continuous casting, multi-pass rolling, and high-temperature annealing in the two-phase region, resulting in a complex process path, relatively high manufacturing costs, and difficulty in forming complex wear-resistant parts.

[0006] This invention addresses the shortcomings of existing metallic materials in terms of low hardness-toughness matching and high production costs under moderate stress impact abrasive wear conditions. By optimizing the alloy composition and employing an isothermal quenching process at the martensitic transformation temperature (Ms), a low-alloy steel with martensite as the main component and a certain amount of metastable retained austenite is obtained. This low-alloy steel maintains high hardness while exhibiting good toughness matching, making it suitable for the preparation of wear-resistant parts under moderate stress impact abrasive wear conditions. Summary of the Invention

[0007] This invention provides a high-hardness and high-toughness quenched-carbon-partitioned wear-resistant steel and its preparation method, with the aim of achieving...

[0008] The above objectives are achieved through the following technical solutions:

[0009] A high-hardness, high-toughness, quenched-carbon-partition wear-resistant steel, wherein the chemical composition and mass content of the high-hardness, high-toughness, quenched-carbon-partition wear-resistant steel are: C: 0.42-0.55%, Si: 2.0-2.8%, Mn: 0.4-0.9%, Cr:

[0010] 1.0-1.6%, Ni: 0.3-0.6%, Mo: 0.4-0.7%, Cu: 0.2-0.6%, Al: 0.5-1.0%, RE: 0.03-0.08%, P≤0.032%, S≤0.040%, balance Fe; and (Mn+Ni+Cu)≤1.7%.

[0011] Preferably, the chemical composition and mass content of the high-hardness and toughness quenched-carbon-partitioned wear-resistant steel are as follows: C: 0.48%, Si: 2.5%, Mn: 0.7%, Ni: 0.5%, Al: 0.7%, Cr: 1.2%, Mo: 0.4%, Cu: 0.3%, RE: 0.03%, P: 0.022%, S: 0.030%, and the balance is Fe.

[0012] The above-mentioned method for preparing high-hardness, high-toughness, quenched-carbon-partition wear-resistant steel includes the following steps:

[0013] S1. Smelting: Metal is added to an electric furnace for smelting, and the molten steel is placed in a steel container to obtain molten steel to be poured.

[0014] S2. Casting: The molten steel to be poured is formed by casting process, and solidified and cooled to obtain castings;

[0015] S3. Normalizing: The obtained castings are cleaned by the casting cleaning system, then sent to the heat treatment furnace, heated, held at the temperature, and then air-cooled to room temperature to obtain the normalized castings.

[0016] S4. Isothermal quenching: The normalized casting is reheated, held at the temperature, and then sent to a salt bath furnace for isothermal quenching and holding. After that, it is taken out of the furnace and air-cooled to room temperature to obtain the isothermal quenched casting.

[0017] S5. Tempering: The isothermal quenched casting is sent back into the heat treatment furnace and heated to 250°C and held for a period of time. Then it is air-cooled to room temperature to obtain high-hardness and toughness quenched-carbon-partitioned wear-resistant steel.

[0018] Preferably, in step S3, the temperature is heated to 950-1020°C and the holding time is 4-8 hours.

[0019] Preferably, the reheating temperature in S4 is 940-980℃, and the holding time is 4-8h.

[0020] Preferably, the isothermal quenching temperature in the salt bath furnace during step S4 is 235-265℃, and the holding time is 3-6 hours.

[0021] Preferably, in step S5, the heating temperature is 250°C and the holding time is 12 hours.

[0022] Preferably, the salt bath medium of S4 comprises 45% NaNO2 and 55% KNO3 by mass percentage.

[0023] Preferably, the molten steel in the steel ladle in S1 is subjected to inoculation and modification treatment using rare earth alloys.

[0024] The high-hardness, high-toughness quenched-carbon-partitioned wear-resistant steel prepared by the aforementioned method is used in the manufacture of wear-resistant parts for use under medium-stress impact abrasive wear conditions in ball mill liners or impact crusher guard plates.

[0025] The beneficial effects of this invention, a high-hardness and high-toughness quenched-carbon-partitioned wear-resistant steel and its preparation method, are as follows:

[0026] The preparation method of this invention is simple and easy to control. It adopts an isothermal quenching heat treatment technique below the Ms point. By rapidly cooling to below the martensitic transformation temperature and holding at that temperature for a period of time, supersaturated carbon atoms in the martensite diffuse into the retained austenite, resulting in a low-alloy steel dominated by martensite with a certain amount of metastable retained austenite. Through the optimized alloy composition and heat treatment process described in this invention, a low-alloy cast steel with a hardness of 582 HV and a V-notch impact absorption energy of 26.5 J is prepared. While the hardness is slightly lower than that of traditional martensitic wear-resistant steel (hardness -598 HV, V-notch impact absorption energy -10.8 J), the impact toughness is significantly improved.

[0027] This wear-resistant cast steel uses Si, Al, and Cr as the main alloying elements, with small amounts of Mn, Ni, Cu, Mo, and appropriate amounts of RE and other alloying elements. After normalizing, isothermal quenching, and tempering heat treatment, a multiphase structure with martensite as the main component and a small amount of metastable austenite is obtained. This multiphase structure maintains high hardness while exhibiting good toughness, showing a good balance between hardness and toughness. While its hardness is slightly lower than that of water-quenched martensite, its toughness is significantly higher than that of water-quenched martensite and high-chromium cast iron. It is suitable for manufacturing wear-resistant parts for medium-stress impact abrasive wear conditions, such as liners for small and medium-sized ball mills and wear plates for impact crushers. At the same time, the production cost is low, and it has a wider range of application prospects. Attached Figure Description

[0028] Figure 1 Heat treatment process diagram of the high-hardness and high-toughness martensitic wear-resistant cast steel produced in Example 3 of this invention.

[0029] Figure 2 Phase composition diagram of the high-hardness, high-toughness, martensitic wear-resistant cast steel EBSD produced in Example 3 of this invention.

[0030] Figure 3 The high-hardness, high-toughness, martensitic wear-resistant cast steel produced in Example 3 of this invention ( Figure 3 a) and Comparative Example 1: Conventional water-quenched martensitic wear-resistant steel ( Figure 3 b) Fracture morphology of V-notch impact specimen.

[0031] Figure 4 The high-hardness, high-toughness, martensitic wear-resistant cast steel produced in Example 3 of this invention ( Figure 4 a) and Comparative Example 1: Conventional water-quenched martensitic wear-resistant steel ( Figure 4 b) Subsurface morphology of wear tracks after impact abrasive wear test.

[0032] Figures 5 to 10 This is a schematic diagram of the casting cleaning system. Detailed Implementation

[0033] A high-hardness, high-toughness quenched carbon-based wear-resistant steel has the following chemical composition and mass percentages: C: 0.42-0.55%, Si: 2.0-2.8%, Mn: 0.4-0.9%, Cr: 1.0-1.6%, Ni: 0.3-0.6%, Mo: 0.4-0.7%, Cu: 0.2-0.5%, Al: 0.5-1.0%, RE: 0.03-0.08%, P≤0.032%, S≤0.040%, with the balance being Fe and unavoidable impurities; and (Mn+Ni+Cu)≤1.7%.

[0034] A method for preparing high-hardness and high-toughness quenched-carbon-partition wear-resistant steel:

[0035] S1) Smelting: Pig iron, scrap steel, pure iron metal and ferroalloys are added to an electric furnace for smelting. The molten steel is placed in a steel ladle and inoculated with rare earth alloys to obtain molten steel to be poured.

[0036] S2) Casting: Molten steel to be poured is formed by casting process, and solidified and cooled to obtain castings;

[0037] S3) Normalizing: The obtained castings are cleaned by the casting cleaning system, then sent to the heat treatment furnace, heated, held at the temperature, and then air-cooled to room temperature to obtain the normalized castings.

[0038] S4) Isothermal quenching: The normalized casting is reheated, held at the temperature, and then sent to a salt bath furnace for isothermal quenching. The quenching temperature is below the martensitic transformation temperature. The casting is held at the temperature and then taken out of the furnace and air-cooled to room temperature to obtain the isothermal quenched casting.

[0039] S5) Tempering: The obtained isothermal quenched casting is sent back to the heat treatment furnace and heated to 250℃ and held for 12 hours. It is then air-cooled to room temperature to obtain high hardness and toughness quenched-carbon-partitioned wear-resistant steel.

[0040] Example 1 of a high-hardness and high-toughness quenched-carbon-partition wear-resistant steel:

[0041] The chemical composition and mass content of the high-hardness and high-toughness martensitic wear-resistant cast steel are as follows: C: 0.42%, Si: 2.1%, Mn: 0.7%, Cr: 1.1%, Ni: 0.6%, Al: 0.6%, Mo: 0.4%, Cu: 0.2%, RE: 0.03%, P: 0.023%, S: 0.038%, with the balance being iron and unavoidable impurities.

[0042] The high-hardness and toughness quenched-carbon-partitioned wear-resistant steel includes the following steps:

[0043] S1) Smelting: Pig iron, scrap steel, pure iron metal and ferroalloys are added to an electric furnace for smelting. The molten steel is placed in a steel container and inoculated with rare earth ferrosilicon alloy to obtain molten steel to be cast.

[0044] S2) Casting: Molten steel to be poured is formed by casting process, and solidified and cooled to obtain castings;

[0045] S3) Normalizing: The obtained castings are cleaned by the casting cleaning system, and then sent to the heat treatment furnace, heated to 1020℃, held for 8 hours and then air-cooled to room temperature to obtain the normalized castings.

[0046] S4) Isothermal quenching: The normalized casting is reheated to 980℃ and held for 8 hours. Then it is sent to a 265℃ salt bath furnace for isothermal quenching and held for 5 hours. The salt bath medium consists of 45% NaNO2 and 55% KNO3. Then it is taken out of the furnace and air-cooled to room temperature to obtain the isothermal quenched casting.

[0047] S5) Tempering: The obtained isothermal quenched casting is sent back to the heat treatment furnace and heated to 250℃ and held for 12 hours. It is then air-cooled to room temperature to obtain high hardness and toughness quenched-carbon-partitioned wear-resistant steel.

[0048] Example 2 of the high-hardness and toughness quenched-carbon-partitioned wear-resistant steel:

[0049] The chemical composition and mass content of the high-hardness and toughness quenched-carbon-partitioned wear-resistant steel are as follows: C: 0.45%, Si: 2.3%, Mn: 0.6%, Cr: 1.3%, Ni: 0.6%, Al: 0.8%, Mo: 0.4%, Cu: 0.3%, RE: 0.03%, P: 0.023%, S: 0.038%, with the balance being iron and unavoidable impurities.

[0050] The preparation method of this high-hardness and high-toughness quenched-carbon-partition wear-resistant steel includes the following steps:

[0051] S1) Smelting: Pig iron, scrap steel, pure iron metal and ferroalloys are added to an electric furnace for smelting. The molten steel is placed in a steel container and inoculated with rare earth ferrosilicon alloy to obtain molten steel to be cast.

[0052] S2) Casting: Molten steel to be poured is formed by casting process, and solidified and cooled to obtain castings;

[0053] S3) Normalizing: The casting is cleaned by the casting cleaning system, then sent to the heat treatment furnace, heated to 1020℃, held for 8 hours and then air-cooled to room temperature to obtain the normalized casting.

[0054] S4) Isothermal quenching: The normalized casting is reheated to 960℃ and held for 8 hours. Then it is sent to a 260℃ salt bath furnace for isothermal quenching and held for 4 hours. The salt bath medium consists of 45% NaNO2 and 55% KNO3. Then it is taken out of the furnace and air-cooled to room temperature to obtain the isothermal quenched casting.

[0055] S5) Tempering: The isothermal quenched casting is sent back into the heat treatment furnace and heated to 250℃ and held for 12 hours. It is then air-cooled to room temperature to obtain high-hardness and toughness quenched-carbon-partitioned wear-resistant steel.

[0056] Example 3 of a high-hardness and toughness quenched-carbon-partition wear-resistant steel:

[0057] The chemical composition and mass content of the high-hardness and toughness quenched-carbon-partitioned wear-resistant steel are as follows: C: 0.48%, Si: 2.5%, Mn: 0.6%, Ni: 0.5%, Cr: 1.2%, Al: 0.8%, Mo: 0.4%, Cu: 0.3%, RE: 0.03%, P: 0.022%, S: 0.030%, with the balance being iron and unavoidable impurities.

[0058] Using the empirical formula Ms=520-320C-50Mn-30Cr-20(Ni+Mo)-5(Cu+Si)+20Al, the martensitic phase transformation temperature of the wear-resistant cast steel of this invention is calculated to be approximately 284.4℃.

[0059] The preparation method of this high-hardness and high-toughness quenched-carbon-partition wear-resistant steel includes the following steps:

[0060] S1) Smelting: Pig iron, scrap steel, pure iron metal and ferroalloys are added to an electric furnace for smelting. The molten steel is placed in a steel container and inoculated with rare earth ferrosilicon alloy to obtain molten steel to be cast.

[0061] S2) Casting: Molten steel to be poured is formed by casting process, and solidified and cooled to obtain castings;

[0062] S3) Normalizing: The casting is cleaned by the casting cleaning system, then sent to the heat treatment furnace, heated to 980℃, held for 8 hours and then air-cooled to room temperature to obtain the normalized casting.

[0063] S4) Isothermal quenching: The normalized casting is reheated to 960℃ and held for 8 hours. Then it is sent to a 260℃ salt bath furnace for isothermal quenching and held for 3.5 hours. The salt bath medium consists of 45% NaNO2 and 55% KNO3. Then it is taken out of the furnace and air-cooled to room temperature to obtain the isothermal quenched casting.

[0064] S5) Tempering: The isothermal quenched casting is sent back into the heat treatment furnace and heated to 250℃ and held for 12 hours. It is then air-cooled to room temperature to obtain high-hardness and toughness quenched-carbon-partitioned wear-resistant steel. Figure 2 In the image, the white portion represents the martensitic matrix, and the black portion represents the retained austenitic phase. Figure 2 and Figure 3 This displays the morphology and content of martensite and retained austenite in the steel. For example... Figure 3 As shown, a large number of dimples can be observed in the impact fracture surface of Example 3, while the number of dimples is significantly reduced in the impact fracture surface of Example 1. Figure 4 As shown, the number and length of wear-marked subsurface fatigue cracks in Example 3 are both less than those in Comparative Example 1.

[0065] Example 4 of a high-hardness and toughness quenched-carbon-partition wear-resistant steel:

[0066] The chemical composition and mass content of the high-hardness and toughness quenched-carbon-partitioned wear-resistant steel are as follows: C: 0.51%, Si: 2.6%, Mn: 0.5%, Cr: 1.1%, Ni: 0.4%, Al: 0.9%, Mo: 0.4%, Cu: 0.3%, RE: 0.03%, P: 0.023%, S: 0.038%, with the balance being iron and unavoidable impurities.

[0067] The preparation method of this high-hardness and high-toughness quenched-carbon-partition wear-resistant steel includes the following steps:

[0068] S1) Smelting: Pig iron, scrap steel, pure iron metal and ferroalloys are added to an electric furnace for smelting. The molten steel is placed in a steel container and inoculated with rare earth ferrosilicon alloy to obtain molten steel to be cast.

[0069] S2) Casting: Molten steel to be poured is formed by casting process, and solidified and cooled to obtain castings;

[0070] S3) Normalizing: The casting is cleaned by the casting cleaning system, then sent to the heat treatment furnace, heated to 950℃, held for 8 hours and then air-cooled to room temperature to obtain the normalized casting.

[0071] S4) Isothermal quenching: The normalized casting is reheated to 950℃ and held for 6 hours. Then it is sent to a 250℃ salt bath furnace for isothermal quenching and held for 3 hours. The salt bath medium consists of 45% NaNO2 and 55% KNO3. Then it is taken out of the furnace and air-cooled to room temperature to obtain the isothermal quenched casting.

[0072] S5) Tempering: The isothermal quenched casting is sent back into the heat treatment furnace and heated to 250℃ and held for 12 hours. It is then air-cooled to room temperature to obtain high-hardness and toughness quenched-carbon-partitioned wear-resistant steel.

[0073] Example 5 of a high-hardness and toughness quenched-carbon-partition wear-resistant steel:

[0074] The chemical composition and mass content of the high-hardness and toughness quenched-carbon-partitioned wear-resistant steel are as follows: C: 0.55%, Si: 2.8%, Mn: 0.5%, Cr: 1.0%, Ni: 0.4%, Al: 1.0%, Mo: 0.4%, Cu: 0.2%, RE: 0.03%, P: 0.023%, S: 0.038%, with the balance being iron and unavoidable impurities.

[0075] The preparation method of this high-hardness and high-toughness quenched-carbon-partition wear-resistant steel includes the following steps:

[0076] S1) Smelting: Pig iron, scrap steel, pure iron metal and ferroalloys are added to an electric furnace for smelting. The molten steel is placed in a steel container and inoculated with rare earth ferrosilicon alloy to obtain molten steel to be cast.

[0077] S2) Casting: Molten steel to be poured is formed by casting process, and solidified and cooled to obtain castings;

[0078] S3) Normalizing: The casting is cleaned by the casting cleaning system, then sent to the heat treatment furnace, heated to 950℃, held for 6 hours and then air-cooled to room temperature to obtain the normalized casting.

[0079] S4) Isothermal quenching: The normalized casting is reheated to 950℃ and held for 6 hours. Then it is sent to a 240℃ salt bath furnace for isothermal quenching and held for 3 hours. The salt bath medium consists of 45% NaNO2 and 55% KNO3. Then it is taken out of the furnace and air-cooled to room temperature to obtain the isothermal quenched casting.

[0080] S5) Tempering: The obtained isothermal quenched casting is sent back to the heat treatment furnace and heated to 250℃ and held for 12 hours. It is then air-cooled to room temperature to obtain high hardness and toughness quenched-carbon-partitioned wear-resistant steel.

[0081] Comparative Example 1: Conventional water-quenched martensitic wear-resistant steel:

[0082] The chemical composition and mass content of the conventional water-quenched martensitic wear-resistant cast steel are as follows: C: 0.48%, Si:

[0083] 2.5%, Mn: 0.6%, Ni: 0.5%, Cr: 1.2%, Al: 0.8%, Mo: 0.4%, Cu: 0.3%, RE: 0.03%, P: 0.022%, S: 0.030%, balance is iron and unavoidable impurities.

[0084] The preparation method of the conventional quenched martensitic wear-resistant cast steel includes the following steps:

[0085] S1) Smelting: Pig iron, scrap steel, pure iron metal and ferroalloys are added to an electric furnace for smelting. The molten steel is placed in a steel container and inoculated with rare earth ferrosilicon alloy to obtain molten steel to be cast.

[0086] S2) Casting: Molten steel to be poured is formed by casting process, and solidified and cooled to obtain castings;

[0087] S3) Normalizing: The casting obtained in step S2 is cleaned of sand and then sent to a heat treatment furnace, heated to 980°C, held for 8 hours and then air-cooled to room temperature to obtain the normalized casting.

[0088] S4) Isothermal quenching: The casting after normalizing in step S3 is reheated to 960℃, held for 8 hours, and then water quenched to room temperature to obtain the casting after conventional water quenching.

[0089] S5) Tempering: The casting after conventional water quenching in step S4 is sent back into the heat treatment furnace and heated to 250℃ and held for 12 hours. It is then air-cooled to room temperature to obtain high-hardness and toughness quenched-carbon-partitioned wear-resistant steel.

[0090] The casting cleaning system described above includes a base 11. The upper end of the base 11 has two openings 12, one in front and one behind. The lower end of the base 11 is fixedly connected to two telescopic cylinders 21, which are arranged one in front and one behind, with the inner side between the two telescopic cylinders 21. The movable ends of the two telescopic cylinders 21 are arranged facing inward. A first connecting plate 22 is fixedly connected to the movable end of the telescopic cylinder 21. The first connecting plate 22 passes through the opening 12 from bottom to top. A bonding component is detachably fixed to the first connecting plate 22. The bonding component is used to contact the surface of the casting. The shape of the inner end face of the bonding component is determined according to the contour of the casting. Different bonding components are gradually replaced according to different castings. The part of the bonding component that contacts the casting is made of a flexible material, such as rubber.

[0091] Furthermore, a ring frame 13 is fixedly connected to the upper end of the base 11, and the cross-section of the ring frame 13 is I-shaped; it also includes a dredging mechanism, which includes a base 51, on which four guide wheels 52 are rotatably connected. The center line of the four guide wheels 52 forms a virtual rectangle. A limiting member 53 is slidably connected to the base 51, and a fastener is threadedly connected to the base 51. The fastener abuts against the limiting member 53 to secure the limiting member 53. A fixing pipe 54 is fixedly connected to the limiting member 53. One end of the fixing pipe 54 is fixedly connected to and connected to one end of a connecting pipe 55. The connecting pipe 55 is preferably a flexible hose. The other end of the connecting pipe 55 is fixedly connected to and connected to a contact head 56. The contact head 56 is preferably a suction cup. The other end of the fixing pipe 54 is used to fix and connect to an air source, such as using an air pump and pipeline to deliver gas to the fixing pipe 54, so that... The contact head 56 generates a blowing force to clean the channels on the casting; four guide wheels 52 roll and rub against the ring frame 13, which is located between two rows of guide wheels 52; further, an annular wall 31 is fixed to the upper end of the base 11, the inner diameter of the annular wall 31 is larger than the diameter of the ring frame 13, the annular wall 31 and the ring frame 13 are concentrically arranged, and the outer ends of the outer row of guide wheels 52 roll and rub against the inner end face of the annular wall 31; preferably, a thickened wall 32 is fixed to the outer wall of the annular wall 31, the height of the thickened wall 32 is the same as the upper end face of the guide wheel 52, a flange is fixed to the upper end of the annular wall 31, the base 51 is higher than the flange, the flange is circumferentially provided with mounting holes, and the base 51 is also provided with mounting holes. The base 51 and the flange are fixed by bolt and nut assemblies passing through the mounting holes, and the orientation of the unblocking mechanism can be changed by the bolt and nut assemblies in different mounting holes;

[0092] Preferably, the limiting member 53 includes a screw, a straight plate, and a base. The screw is rotatably connected to the base, the straight plate is fixed to the base, and the fixing tube 54 is fixed to the upper end of the base. The screw is threadedly connected to the base 51, and the straight plate is slidably connected to the base 51. The contact head 56 is pressed against the casting through the screw thread transmission. The contact head 56 is kept in close contact with the casting through the thread self-locking and friction pre-tightening, so that high-pressure gas can be injected into the channel.

[0093] The unblocking mechanism is provided in two parts, such that one contact head 56 faces one end of the channel of the casting and the other contact head 56 faces the other end of the channel of the casting.

[0094] Furthermore, a vibrator is fixed to the bottom of the base 11, and the casting cleaning system also includes a reset assembly, see details below. Figure 9The reset assembly includes a second connecting plate 41, with two first round steel bars 42 fixedly connected to the right end of the second connecting plate 41. A first base frame 43 is slidably connected to the two first round steel bars 42. A third connecting plate 44 is fixedly connected to the right end of the two first round steel bars 42. The first base frame 43 can slide left and right on the first round steel bars 42. First compression springs are sleeved on both sides of the first round steel bars 42. The inner end of the first compression spring contacts the first base frame 43, the outer end of the first compression spring on the left side contacts the second connecting plate 41, and the outer end of the first compression spring on the right side contacts the third connecting plate 44. Second round steel bars 45 are fixedly connected to both the front and rear ends of the first base frame 43. A limiting part is fixedly connected to the end of the second round steel bar 45 away from the first base frame 43. A second compression spring is sleeved on both the front and rear sides of each second round steel bar 45. The two ends of the second compression spring contact the first base frame 43 and the limiting part, respectively. The assembly also includes a U-shaped second base frame 46. The front and rear sides of the frame 46 are slidably connected to two second round steel bars 45 respectively. The inner end of the second compression spring abuts against the second base frame 46. The outer end of the second compression spring on the outer side contacts the limiting part, and the outer end of the second compression spring on the inner side contacts the first base frame 43. The right end of the second base frame 46 is fixedly connected to a shaft 61, and a shaft seat 62 is rotatably connected to the shaft 61. The reset assembly is provided in two mirror images. The two reset assemblies are located on the left and right sides of the base 11 respectively. The two second connecting plates 41 are fixedly connected to the left and right ends of the base 11 respectively. A reduction motor 63 is fixedly connected to the shaft 61 on the right side. The reduction motor 63 is used to rotate the shaft 61 around the output shaft of the reduction motor 63. The shaft 61 drives the second base frame 46 to rotate around the output shaft of the reduction motor 63, so that the reset assembly drives the base 11 to rotate around the output shaft of the reduction motor 63. As the vibrator is started, the base 11 can shake left and right and up and down to shake off the sand in the channel or on the surface of the casting.

[0095] Example and comparative material performance tests:

[0096] Experimental Methods: Performance tests were conducted on the cast steels prepared in Examples 1-5 and Comparative Example 1. The impact test used V-notch impact specimens of 10×10×55mm³. Before the Vickers hardness test, the test surfaces of the specimens were ground and polished. The test load was 50g, and the loading time was 15s. The impact abrasive wear test was conducted on an MLD-10 dynamic load abrasive wear testing machine. The wear impact energy was 1.0J, the impact frequency was 100 times per minute, the lower specimen was 45# steel, the rotation speed was 100 revolutions per minute, and the abrasive was quartz sand with a particle size between 60 and 80 mesh. The abrasive flow rate was controlled at approximately 50 kg per hour. Each group of specimens needed to be pre-ground for 30 minutes before the test. During the impact wear process, the weight loss was measured once every 30 minutes as one wear cycle. A total of five cycles were conducted, for a total of 2.5 hours. The test results are listed in Table 1.

[0097] Table 1 Performance Test Results:

[0098]

[0099] The hardness in Table 1 is the average of 10 values, and the V-notch impact energy absorption and wear weight loss are the average of 3 values.

[0100] Table 1 shows that the metastable retained austenite transforms into martensite under certain stress and strain conditions, accompanied by volume expansion. This leads to local stress relaxation, increases the ability to deform uniformly before shrinkage, and enhances both strength and plasticity, exhibiting a transformation-induced plasticity (TRIP) effect. This results in a good balance between hardness and toughness in the multiphase structure. While the hardness of this low-alloy steel is 535-582 HV, its V-notch impact absorption energy can still reach 17.6-26.5 J, demonstrating a high hardness-toughness balance superior to currently used martensitic cast steels and high-chromium cast irons.

[0101] Under the same composition but different process treatment, the hardness of Example 3 was reduced by about 3% (16HV) compared with that of Comparative Example 1, but the V-notch impact absorption energy of the former was 2.45 times that of the latter. The obvious difference between the present invention and existing cast steel is: (1) It has higher Si and Al elements and a certain content of Mn, Ni and Cu, (Mn+Ni+Cu)≤1.7%. The precipitation of carbides will significantly reduce the impact toughness of the material, and Si and Al elements help to suppress the precipitation of carbides. C, Mn, Ni and Cu are all austenite stabilizing elements, which can ensure the formation of a certain amount of metastable residual austenite structure during isothermal quenching below Ms point, but C, Mn, Ni and Cu need to be controlled, otherwise the increase of austenite content will not only reduce the hardness of the material but also weaken the stability of the residual austenite and reduce the toughness of the material. (2) Quench to a temperature below Ms point and hold for a period of time. During isothermal treatment below the Ms point, supersaturated carbon atoms diffuse from martensite into the retained austenite, meaning carbon atoms are enriched in the metastable retained austenite, enhancing its stability. Furthermore, both isothermal temperature and isothermal time affect the martensitic phase transformation behavior and the thermodynamic behavior of carbon atom diffusion. Excessively high temperatures or short times weaken the enrichment of carbon atoms in the retained austenite, thereby reducing its stability and impact toughness. Martensitic matrix structures have high hardness. The elimination of carbides and the formation of metastable retained austenite (TRIP effect) can significantly improve the material's toughness. This invention, through optimized composition design and appropriate isothermal quenching (below the Ms point) heat treatment, enables low-alloy steel to maintain high hardness while retaining excellent toughness, overcoming the shortcomings of existing metallic materials with poor hardness-toughness matching and high production costs under moderate stress impact abrasive wear conditions. Quenched-carbon steel, which combines high hardness and excellent impact toughness, exhibits better wear resistance than traditional water-quenched martensitic steel in medium impact abrasive wear tests. It is especially suitable for manufacturing wear-resistant parts used under medium stress impact abrasive wear conditions, such as ball mill liners and impact crusher guard plates.

Claims

1. A method of manufacturing a high hard tough quenched-carbide partition wear resistant steel, characterized in that, The preparation method comprises the following steps: S1, smelting: adding pig iron, scrap steel, pure iron metal and iron alloy into an electric furnace for smelting, placing the tapped molten steel in a steel ladle, and performing inoculation modification treatment with a rare earth alloy to obtain a molten steel to be poured; S2, casting forming: the molten steel to be poured is formed by a casting process to obtain a casting after solidification and cooling; S3, normalizing: the obtained casting is subjected to sand cleaning treatment by a casting cleaning system, and then is sent into a heat treatment furnace, heated to 950-1020 DEG C, and kept for 4-8 h, and then air-cooled to room temperature to obtain a normalized casting; S4, isothermal quenching: the normalized casting is re-heated to 940-980 DEG C and kept for 4-8 h, and then is sent into a salt bath furnace for isothermal quenching at 235-265 DEG C for 3-6 h, and then is air-cooled to room temperature to obtain an isothermally quenched casting; S5, tempering: the isothermally quenched casting is again sent into a heat treatment furnace and heated to 250 DEG C and kept, and then air-cooled to room temperature to obtain a high-hardness-and-toughness quenched-carbon-partitioning wear-resistant steel. The high-hardness-and-toughness quenched-carbon-partitioning wear-resistant steel has the following chemical components and mass contents: C: 0.42-0.55%, Si: 2.0-2.8%, Mn: 0.4-0.9%, Cr: 1.0-1.6%, Ni: 0.3-0.6%, Mo: 0.4-0.7%, Cu: 0.2-0.6%, Al: 0.5-1.0%, RE: 0.03-0.08%, P ≤ 0.032%, S ≤ 0.040%, and the balance of Fe; and (Mn+Ni+Cu) ≤ 1.7%.

2. The preparation method of the high-hardness-and-toughness quenched-carbon-partitioning wear-resistant steel according to claim 1, wherein the holding time in S5 is 12 h.

3. The preparation method of the high-hardness-and-toughness quenched-carbon-partitioning wear-resistant steel according to claim 1, wherein the salt bath medium in S4 comprises 45% of NaNO2 and 55% of KNO3 by mass percentage.

4. The preparation method of the high-hardness-and-toughness quenched-carbon-partitioning wear-resistant steel according to claim 1, wherein the high-hardness-and-toughness quenched-carbon-partitioning wear-resistant steel has the following chemical components and mass contents: C: 0.48%, Si: 2.5%, Mn: 0.7%, Ni: 0.5%, Al: 0.7%, Cr: 1.2%, Mo: 0.4%, Cu: 0.3%, RE: 0.03%, P: 0.022%, S: 0.030%, and the balance of Fe.

5. The high-hardness-and-toughness quenched-carbon-partitioning wear-resistant steel prepared by the preparation method of the high-hardness-and-toughness quenched-carbon-partitioning wear-resistant steel according to any one of claims 1 to 4, which is applied to a wear-resistant part used in a medium-stress impact abrasive wear working condition in the manufacture of a ball mill liner or an impact crusher guard.

Images