Agricultural machinery steel substrate, agricultural machinery wear-resistant part and preparation method

Abstract

The application provides a steel base plate for agricultural machinery, an agricultural machinery wear-resistant part and a preparation method, and belongs to the field of steel preparation.The chemical composition of the steel base plate for agricultural machinery comprises the following components in mass fraction: C: 0.27% to 0.40%, Si: 0.1% to 1.2%, Mn: 0.5% to 2.7%, P: ≤0.025%, S: ≤0.035%, Alt: 0.01% to 0.70%, B: 0.001% to 0.008%, Cu: 0.1% to 1.0%, Cr: 0.1% to 1.3%, Ni: 0.05% to 0.3%, Mo: 0.03% to 0.3%, Sn: 0.01% to 0.3%, Ti: 0.01% to 0.08%, and the balance of Fe and inevitable impurities, so that the technical problem that the prior art is difficult to improve corrosion resistance on the basis of meeting the high toughness and high wear resistance of the steel base plate for agricultural machinery is solved.

Description

Technical Field

[0001] This application relates to the field of steel preparation technology, and in particular to a steel base plate for agricultural machinery, wear-resistant parts for agricultural machinery, and a preparation method thereof. Background Technology

[0002] Agricultural machinery wear-resistant parts operate in harsh environments, including impacts from rocks and soil corrosion. These parts require high wear resistance, high toughness, and high corrosion resistance. Impact damage leading to breakage, fracture, and corrosion are common failure modes. Currently, most wear-resistant steels used in agricultural machinery lack corrosion resistance. Agricultural machinery operates seasonally, making it susceptible to corrosion during seasonal transitions, sometimes even rusting within days, thus impacting the service life of parts. Therefore, improving corrosion resistance while maintaining the high toughness and wear resistance of steel base plates for agricultural machinery is a pressing technical challenge. Summary of the Invention

[0003] This application provides a steel base plate for agricultural machinery, wear-resistant parts for agricultural machinery, and a method for preparing them, in order to solve the technical problem that existing technologies are unable to improve corrosion resistance while meeting the requirements of high toughness and high wear resistance for steel base plates for agricultural machinery.

[0004] In a first aspect, this application provides a steel substrate for agricultural machinery, wherein the chemical composition of the steel substrate for agricultural machinery, by mass fraction, includes: C: 0.27%~0.40%, Si: 0.1%~1.2%, Mn: 0.5%~2.7%, P≤0.025%, S≤0.035%, Alt: 0.01%~0.70%, B: 0.001%~0.008%, Cu: 0.1%~1.0%, Cr: 0.1%~1.3%, Ni: 0.05%~0.3%, Mo: 0.03%~0.3%, Sn: 0.01%~0.3%, Ti: 0.01%~0.08%, with the balance being Fe and unavoidable impurities.

[0005] Optionally, the metallographic structure of the steel substrate for agricultural machinery includes ferrite and pearlite, and the steel substrate for agricultural machinery satisfies at least one of the following properties: yield strength of 500MPa~650MPa, tensile strength of 700MPa~800MPa, and elongation after fracture A50 of 15%~25%.

[0006] Secondly, this application provides a method for preparing the steel substrate for agricultural machinery as described in the embodiments of the first aspect, the method comprising:

[0007] A cast billet having the aforementioned chemical composition is obtained;

[0008] The billet is heated, rough descaled, rough rolled, fine descaled, and fine rolled to obtain a hot-rolled coil.

[0009] The hot-rolled coil is subjected to a first cooling, winding, and a second cooling to obtain a steel substrate for agricultural machinery.

[0010] Optionally, the step of heating, rough descaling, rough rolling, fine descaling, and fine rolling of the cast billet to obtain a hot-rolled coil includes:

[0011] The billet is hot-charged into the heating furnace, and the temperature of the hot-charged billet is controlled to be ≥400℃ and the residual oxygen value in the atmosphere of the heating furnace is ≤3%. Then, the first heating is performed, and the following parameters of the first heating are controlled: the first heating endpoint temperature and the first heating holding time.

[0012] The billet after the first heating is subjected to a second heating, and the following parameters of the second heating are controlled: the second heating endpoint temperature and the second heating time;

[0013] The billet after the second heating is subjected to a third heating, and the following parameters of the third heating are controlled: the end temperature of the third heating and the heating time of the third heating;

[0014] The billet after the third heating is subjected to a fourth heating, and the following parameters of the fourth heating are controlled: the fourth heating endpoint temperature, the fourth heating rise time and the fourth heating holding time. Rough descaling, rough rolling, fine descaling and fine rolling are performed to obtain a hot-rolled coil.

[0015] Optionally, the first heating endpoint temperature is 600℃~700℃, and the first heating holding time is 40min~70min;

[0016] The second heating endpoint temperature is 700℃~1100℃, and the second heating time is 10min~40min;

[0017] The third heating endpoint temperature is 1100℃~1150℃, and the third heating time is 30min~50min;

[0018] The fourth heating endpoint temperature is 1150℃~1250℃, the fourth heating rise time is 20min~40min, and the fourth heating hold time is ≤50min.

[0019] Optionally, the pressure of rough descaling is 20MPa~24MPa; the number of descaling passes in the rough rolling is ≥4, and the descaling pressure is 18MPa~23MPa; the pressure of fine descaling is 21MPa~25MPa; the inlet temperature of the fine rolling is 980℃~1060℃, and the final rolling temperature is 860℃~900℃.

[0020] Optionally, the winding temperature is 580℃~700℃, the front winding tension is ≥43MPa, and the high winding tension section of the inner ring is ≥10% of the diameter.

[0021] Thirdly, this application provides a method for preparing wear-resistant parts for agricultural machinery, the method comprising:

[0022] The steel base plate for agricultural machinery described in the first aspect embodiment is cut into blanks to obtain a sheet material;

[0023] The material sheet is heated and then subjected to hot pressing quenching, with the cooling water temperature controlled at 35℃~45℃ to obtain wear-resistant parts for agricultural machinery.

[0024] Optionally, the final heating temperature is 850℃~950℃, and the holding time during heating satisfies the following relationship: t=d+1,

[0025] In the formula, t represents the heat preservation time, and d represents the thickness of the steel base plate for agricultural machinery.

[0026] Fourthly, this application provides an agricultural machinery wear-resistant part prepared by the method described in the second aspect embodiment, wherein the metallographic structure of the agricultural machinery wear-resistant part includes martensite, and the agricultural machinery wear-resistant part satisfies at least one of the following properties: hardness of 51HRC~53HRC, yield strength of 1350MPa~1450MPa, tensile strength of 1750MPa~1850MPa, and elongation after fracture A50 of 7%~9%.

[0027] The technical solutions provided in this application have the following advantages compared with the prior art:

[0028] This application provides a steel base plate for agricultural machinery, which increases the Cr content and simultaneously adds alloying elements such as Cu, Ni, Mo, and Sn to the existing C-Si-Mn-Cr-B boron steel composition system. Increasing the Cr content improves hardenability, thus enhancing toughness and corrosion resistance while maintaining the hardness and wear resistance of the parts. Adding Cu improves corrosion resistance; adding Mo improves hardenability, maintains hardness, and enhances corrosion resistance; adding Sn improves corrosion resistance; and adding Ni improves toughness. This solves the technical problem of existing technologies that struggle to improve corrosion resistance while meeting the high toughness and high wear resistance requirements of agricultural machinery steel base plates. The resulting agricultural machinery steel base plate has a yield strength of 500MPa~650MPa, a tensile strength of 700MPa~800MPa, and an elongation at break (A50) of 15%~25%, meeting the requirements for wear-resistant parts in agricultural machinery. Attached Figure Description

[0029] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0030] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A schematic flowchart illustrating a method for preparing a steel substrate for agricultural machinery, provided in an embodiment of this application;

[0032] Figure 2 A process route diagram for hot pressing quenching of wear-resistant parts for agricultural machinery is provided for Embodiment 1 of this application;

[0033] Figure 3 A schematic diagram showing the location for measuring hardness in the embodiments and comparative examples of this application;

[0034] Figure 4 A metallographic image of the core of the steel substrate for agricultural machinery provided in Embodiment 1 of this application;

[0035] Figure 5 This is a metallographic image of the edge of a steel substrate for agricultural machinery provided in Embodiment 1 of this application;

[0036] Figure 6 A metallographic image of the core of the wear-resistant agricultural machinery part provided in Embodiment 1 of this application;

[0037] Figure 7 A metallographic image of the edge of the wear-resistant agricultural machinery part provided in Embodiment 1 of this application. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0040] Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0041] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0042] This application provides a steel substrate for agricultural machinery. The chemical composition of the steel substrate for agricultural machinery, by mass fraction, includes: C: 0.27%~0.40%, Si: 0.1%~1.2%, Mn: 0.5%~2.7%, P≤0.025%, S≤0.035%, Alt: 0.01%~0.70%, B: 0.001%~0.008%, Cu: 0.1%~1.0%, Cr: 0.1%~1.3%, Ni: 0.05%~0.3%, Mo: 0.03%~0.3%, Sn: 0.01%~0.3%, Ti: 0.01%~0.08%, with the balance being Fe and unavoidable impurities.

[0043] The positive effects of controlling the carbon content to 0.27%~0.40% are: sufficient carbon ensures the hardness and strength of the martensitic structure in the final part, guaranteeing its service life in agricultural work; however, the carbon content should not be too high, as excessive carbon content will significantly reduce the plasticity and toughness of the part, making it prone to brittle fracture during agricultural service. Furthermore, excessive carbon content can easily cause cracks during continuous casting and hot rolling, increasing manufacturing risks. For example, the carbon content can be 0.27%, 0.30%, 0.32%, 0.34%, 0.36%, 0.38%, 0.40%, etc.

[0044] The positive effects of controlling the Si content to 0.1%~1.2%: Si is a common element in steel. Si can increase strength, hardness, and wear resistance. However, excessive Si content will affect the surface quality of hot-rolled plates. For example, the Si content is 0.1%, 0.3%, 0.4%, 0.5%, 0.6%, 0.8%, 0.9%, 1.1%, and 1.2%.

[0045] The positive effects of controlling the Mn content to 0.5%~2.7% include: Mn can improve strength, hardness, and wear resistance, and enhance the hardenability of steel. However, excessive Mn content should not be too high, as it can affect the control of hot-rolled strip formation, the uniformity of hardness after heat treatment, and ultimately, the wear resistance. Examples of Mn contents include 0.5%, 1.0%, 1.5%, 1.8%, 2.0%, 2.2%, 2.5%, and 2.7%.

[0046] The positive effects of controlling the content of phosphorus (P) to ≤0.025% and sulfur (S) to ≤0.035% are that, as harmful elements, the content of P and S is controlled to be as low as possible. For example, the content of P can be 0.005%, 0.010%, 0.015%, 0.020%, 0.025%, etc., and the content of S can be 0.005%, 0.008%, 0.010%, 0.015%, 0.020%, 0.025%, 0.035%, etc.

[0047] The positive effects of controlling the Alt content to 0.01%~0.70%: Alt is typically added to steel as a deoxidizer. Examples of Alt content include 0.01%, 0.03%, 0.06%, 0.08%, 0.10%, 0.15%, 0.18%, 0.20%, 0.25%, 0.28%, 0.3%, 0.4%, 0.5%, 0.6%, and 0.70%.

[0048] The positive effects of controlling the boron content to 0.001%~0.008% are as follows: Boron's core function is to lower the critical cooling rate, improve hardenability, ensure that every part of the component has a martensitic structure, and ultimately guarantee wear resistance. For example, the boron content can be 0.001%, 0.002%, 0.003%, 0.005%, 0.006%, 0.007%, 0.008%, etc.

[0049] The positive effects of controlling the Cu content to 0.1%~1.0% include improved corrosion resistance. For example, the Cu content can be 0.1%, 0.2%, 0.4%, 0.5%, 0.6%, 0.8%, 0.9%, 1.0%, etc.

[0050] The positive effects of controlling the Cr content to 0.1%~1.3% include: Cr improves wear resistance and corrosion resistance; however, the Cr content should not be too high, as excessive Cr content can easily lead to brittleness during manufacturing and service. For example, the Cr content can be 0.1%, 0.2%, 0.3%, 0.5%, 0.7%, 0.8%, 1.0%, 1.2%, 1.3%, etc.

[0051] The positive effects of controlling the Ni content to 0.05%~0.3% are that Ni mainly helps to suppress copper embrittlement in steel during the heating furnace. Examples of Ni content include 0.05%, 0.08%, 0.10%, 0.15%, 0.18%, 0.20%, 0.25%, 0.28%, and 0.3%.

[0052] The positive effects of controlling the Mo content to 0.03%~0.3% include: Mo is beneficial for improving hardenability, strength, and corrosion resistance; however, Mo is a relatively expensive alloy and should not be added too high. For example, the Mo content can be 0.03%, 0.06%, 0.08%, 0.10%, 0.15%, 0.18%, 0.20%, 0.25%, 0.28%, 0.3%, etc.

[0053] The positive effects of controlling the Sn content to 0.01%~0.3% include: Sn can inhibit oxidation of the steel surface and improve its clay properties during service; however, the content should not be too high, as this will lead to increased brittleness during production. Examples of Sn content include 0.01%, 0.05%, 0.08%, 0.10%, 0.15%, 0.18%, 0.20%, 0.25%, 0.28%, and 0.3%.

[0054] The positive effects of controlling the Ti content to 0.01%~0.08% are as follows: Ti combines with N, preventing N and B from combining to form boron nitride. The formation of boron nitride reduces the effect of B, which is an element that improves hardenability. For example, the Ti content can be 0.01%, 0.02%, 0.03%, 0.05%, 0.06%, 0.07%, 0.08%, etc.

[0055] In some embodiments, the metallographic structure of the agricultural machinery steel substrate includes ferrite and pearlite, and the agricultural machinery steel substrate satisfies at least one of the following properties: yield strength of 500MPa~650MPa, tensile strength of 700MPa~800MPa, and elongation after fracture A50 of 15%~25%.

[0056] The C-Si-Mn-B-Mo-Cu-Cr-Ni-Sn composition system improves the corrosion resistance of the steel substrate for agricultural machinery while meeting the requirements of high toughness and high wear resistance. For example, the yield strength can be 500MPa, 520MPa, 550MPa, 580MPa, 600MPa, 620MPa, 650MPa, etc., the tensile strength can be 700MPa, 720MPa, 730MPa, 740MPa, 760MPa, 780MPa, 790MPa, 800MPa, etc., and the elongation after fracture (A50) can be 15%, 16%, 17%, 18%, 20%, 22%, 24%, 25%, etc.

[0057] Figure 1 This is a schematic flowchart illustrating a method for preparing a steel substrate for agricultural machinery, as provided in an embodiment of this application.

[0058] Please see Figure 1 This application provides a method for preparing a steel substrate for agricultural machinery, the method comprising:

[0059] S11. Obtain a cast billet having the aforementioned chemical composition;

[0060] In some implementations, step S1 may be preceded by smelting, refining, or continuous casting.

[0061] S21. The billet is heated, rough descaled, rough rolled, fine descaled and fine rolled to obtain a hot-rolled coil;

[0062] In some embodiments, the step of heating the billet, rough descaling, rough rolling, fine descaling, and fine rolling to obtain a hot-rolled coil includes:

[0063] The billet is hot-charged into the heating furnace, and the temperature of the hot-charged billet is controlled to be ≥400℃ and the residual oxygen value in the atmosphere of the heating furnace is ≤3%. Then, the first heating is performed, and the following parameters of the first heating are controlled: the first heating endpoint temperature and the first heating holding time.

[0064] The billet after the first heating is subjected to a second heating, and the following parameters of the second heating are controlled: the second heating endpoint temperature and the second heating time;

[0065] The billet after the second heating is subjected to a third heating, and the following parameters of the third heating are controlled: the end temperature of the third heating and the heating time of the third heating;

[0066] The billet after the third heating is subjected to a fourth heating, and the following parameters of the fourth heating are controlled: the fourth heating endpoint temperature, the fourth heating rise time and the fourth heating holding time. Rough descaling, rough rolling, fine descaling and fine rolling are performed to obtain a hot-rolled coil.

[0067] In the embodiments of this application, by controlling the temperature of the hot-charged billet to ≥400℃, cracks in the billet are avoided. For example, the billet temperature during hot charging can be 400℃, 410℃, 430℃, 440℃, 460℃, 480℃, 500℃, etc. By employing a weakly reducing atmosphere and controlling the residual oxygen value in the heating furnace to ≤3%, decarburization and intergranular oxidation are suppressed. For example, the residual oxygen value in the heating furnace can be 1%, 1.5%, 2.0%, 2.5%, 3%, etc.

[0068] In some embodiments, the first heating endpoint temperature is 600℃~700℃, and the first heating holding time is 40min~70min;

[0069] The second heating endpoint temperature is 700℃~1100℃, and the second heating time is 10min~40min;

[0070] The third heating endpoint temperature is 1100℃~1150℃, and the third heating time is 30min~50min;

[0071] The fourth heating endpoint temperature is 1150℃~1250℃, the fourth heating rise time is 20min~40min, and the fourth heating hold time is ≤50min.

[0072] In the embodiments of this application, the first heating stage is a heat recovery section, which recovers and utilizes the residual heat from the heating of the previous batch of cast billets, saving resources. The second heating stage is a preheating stage. The fourth heating stage ensures rolling stability and avoids overheating of the slab. After heating, the cast billet has good plasticity, low deformation resistance, and is easily subjected to plastic deformation. In addition, the heating process can also improve certain structural defects (such as uneven composition) introduced during casting and eliminate internal stress in the steel. Therefore, heating plays an important role in ensuring the quality of rolled products, improving various indicators of the rolling mill, and achieving normal rolling. For example, the first heating endpoint temperature can be 600℃, 620℃, 630℃, 650℃, 660℃, 680℃, 700℃, etc., and the first heating holding time can be 40min, 50min, 55min, 60min, 65min, 70min, etc.; the second heating endpoint temperature can be 700℃, 800℃, 900℃, 1000℃, 1100℃, etc., and the second heating rise time can be 10min, 20min, 30min, 35min, 40min, etc.; the third heating endpoint temperature can be 1100℃, 1110℃, 1120℃, etc. The third heating temperature can be 1150℃, 1130℃, 1140℃, 1150℃, etc., and the third heating time can be 30min, 35min, 40min, 45min, 50min, etc.; the fourth heating endpoint temperature can be 1150℃, 1160℃, 1180℃, 1200℃, 1210℃, 1230℃, 1240℃, 1250℃, etc., and the fourth heating time can be 20min, 25min, 30min, 34min, 40min, etc.; the fourth heating holding time can be 20min, 30min, 40min, 45min, 50min, etc.

[0073] In some embodiments, the pressure of rough descaling is 20MPa~24MPa; the number of descaling passes in the rough rolling is ≥4, and the descaling pressure is 18MPa~23MPa; the pressure of fine descaling is 21MPa~25MPa; the inlet temperature of the fine rolling is 980℃~1060℃, and the final rolling temperature is 860℃~900℃.

[0074] In the embodiments of this application, by controlling the descaling process parameters, clean descaling is ensured, avoiding defects such as the formation of iron oxide scale on the hot-rolled surface. For example, the pressure of the rough descaling can be 20 MPa, 21 MPa, 22 MPa, 23 MPa, 24 MPa, etc.; the number of descaling passes in the rough rolling can be 4, 5, 6, 7, etc., and the descaling pressure can be 18 MPa, 19 MPa, 20 MPa, 21 MPa, 22 MPa, 23 MPa, etc.; the pressure of the fine descaling can be 21 MPa, 22 MPa, 23 MPa, 24 MPa, 25 MPa, etc. By controlling the rolling temperature, smooth rolling and obtaining a good sheet shape are ensured. For example, the inlet temperature of the finishing mill can be 980℃, 990℃, 1000℃, 1020℃, 1030℃, 1040℃, 1060℃, etc., and the finishing temperature can be 860℃, 870℃, 880℃, 890℃, 900℃, etc.

[0075] S31. The hot-rolled coil is subjected to first cooling, winding and second cooling to obtain a steel base plate for agricultural machinery.

[0076] In some implementations, the first cooling is laminar flow cooling.

[0077] In some embodiments, the winding temperature is 580°C to 700°C, the front winding tension is ≥43MPa, and the high winding tension section of the inner ring is ≥10% of the diameter.

[0078] In the embodiments of this application, by employing a relatively low winding temperature, the strip thickness is guaranteed to be ≤2.0 grade, ensuring the uniformity of the microstructure and hardness of the agricultural machinery parts after heat treatment, and guaranteeing high wear resistance. By employing high winding tension at the front end (≥43MPa) and a high winding tension section at the inner ring (≥10% of the diameter), flattening of thin-gauge products is prevented, ensuring good roll shape. This ensures stable production and prevents defects such as scratches. For example, the winding temperature can be 580℃, 600℃, 620℃, 640℃, 660℃, 680℃, 700℃, etc., the front winding tension can be 43MPa, 43.2MPa, 43.5MPa, 43.8MPa, 44.0MPa, 44.2MPa, etc., and the high winding tension section of the inner ring is 10%, 10.2%, 10.5%, 10.8%, 11.0%, 11.2%, 11.5% of the diameter, etc.

[0079] In some embodiments, the second cooling specifically involves: after the hot-rolled coil reaches its lower limit, it enters a slow cooling pit, and the time from leaving the production line to entering the slow cooling pit is 15 to 30 minutes.

[0080] In the embodiments of this application, by employing a slow cooling pit, white spots in the steel are eliminated and cracks caused by thermal stress and structural stress during recooling are avoided. For example, the time from when the hot-rolled coil comes off the production line to when it enters the slow cooling pit can be 15 min, 17 min, 20 min, 22 min, 25 min, 28 min, 30 min, etc.

[0081] The product prepared by the method for preparing the steel substrate for agricultural machinery is the aforementioned steel substrate for agricultural machinery. The chemical composition and microstructure of the steel substrate for agricultural machinery prepared by the method can be referred to the above embodiments. Since the method for preparing the steel substrate for agricultural machinery adopts some or all of the technical solutions of the embodiments of the steel substrate for agricultural machinery, it has at least all the beneficial effects brought about by the technical solutions of the embodiments of the steel substrate for agricultural machinery, which will not be elaborated here.

[0082] Figure 2 A process route diagram for hot pressing quenching of wear-resistant parts for agricultural machinery is provided for Embodiment 1 of this application.

[0083] Please see Figure 2 This application provides a method for preparing wear-resistant parts for agricultural machinery, the method comprising:

[0084] S12. Cut the steel base plate for agricultural machinery into sheet material;

[0085] In some implementations, step S12 is preceded by uncoiling. By uncoiling, the steel coil is first flattened into a flat sheet.

[0086] In some embodiments, the method further includes: finishing. Through finishing, the edges of the blanked sheet are finished to obtain good edge quality, and the edges of some rough-cut discs have a toothed shape.

[0087] S22. The material sheet is heated and then hot-pressed and quenched, and the cooling water temperature of the hot-pressing and quenching is controlled at 35℃~45℃ to obtain wear-resistant parts for agricultural machinery.

[0088] The finely processed sheet material is heated in a tunnel furnace, which is protected by inert gases such as nitrogen to prevent the oxide scale on the surface of the disc from becoming too thick or even causing defects such as pitting.

[0089] After the material sheet exits the tunnel furnace, it is transported to the hot pressing quenching mold by a robot or conveyor belt. There are evenly distributed water channels between the upper and lower molds of the hot pressing quenching mold. On the one hand, this ensures the dimensional accuracy after pressing and quenching, and on the other hand, it ensures that a martensitic matrix structure is obtained, thus guaranteeing hardness and wear resistance.

[0090] By controlling the uniformity of water distribution and temperature during hot pressing, the water temperature is maintained at 35℃~40℃. Circulating cooling water is required to ensure this temperature and uniform hardness. Furthermore, hot pressing guarantees dimensional accuracy, with fluctuations within 1mm. For example, the cooling water temperature for this hot pressing can be 35℃, 37℃, 39℃, 40℃, 42℃, 44℃, 45℃, etc.

[0091] In some embodiments, the method further includes shot peening and baking paint. The hot-pressed and quenched disc is shot peened to remove the surface oxide scale, and then baked paint is applied.

[0092] In some embodiments, the final heating temperature is 850℃~950℃, and the holding time of the heating satisfies the following relationship: t=d+1,

[0093] In the formula, t represents the heat preservation time, and d represents the thickness of the steel base plate for agricultural machinery.

[0094] By controlling the heating process parameters, it is possible to ensure complete austenitization of the material sheet while avoiding excessively high temperatures or prolonged heating times, which could lead to abnormal growth of the original austenite grains. For example, the final heating temperature can be 850℃, 870℃, 880℃, 890℃, 900℃, 920℃, 940℃, 950℃, etc.

[0095] This application provides a wear-resistant part for agricultural machinery. The metallographic structure of the wear-resistant part includes martensite. The wear-resistant part satisfies at least one of the following properties: hardness of 51HRC~53HRC, yield strength of 1350MPa~1450MPa, tensile strength of 1750MPa~1850MPa, and elongation after fracture A50 of 7%~9%.

[0096] A high-hardness microstructure with martensite as the matrix is ​​obtained through hot pressing and quenching, ensuring uniformity of microstructure and hardness. This guarantees high wear resistance while also ensuring toughness, corrosion resistance, and non-coating properties. For example, the hardness can be 51HRC, 51.5HRC, 52HRC, 52.5HRC, 52.8HRC, 53HRC, etc.; the yield strength can be 1350MPa, 1370MPa, 1390MPa, 1410MPa, 1430MPa, 1450MPa, etc.; the tensile strength can be 1750MPa, 1770MPa, 1790MPa, 1800MPa, 1820MPa, 1840MPa, 1850MPa, etc.; and the elongation after fracture (A50) can be 7%, 7.5%, 8%, 8.5%, 8.8%, 9%, etc.

[0097] This agricultural machinery wear-resistant part is realized based on the above-mentioned preparation method of agricultural machinery wear-resistant parts. The specific steps of the preparation method of agricultural machinery wear-resistant parts can be referred to the above embodiments. Since this agricultural machinery wear-resistant part adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0098] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0099] Example 1

[0100] The preparation process of the agricultural machinery steel substrate in this embodiment is as follows: KR desulfurization, converter smelting, LF refining, RH refining, and continuous casting; the continuously cast billet needs to be hot-charged, with a charging temperature of 560°C. The heating furnace is divided into a heat recovery section, a preheating section, a first-stage heating section, a second-stage heating section, and a soaking section. The heating time in the furnace is 200 min, using a weakly reducing atmosphere, with a soaking temperature of 1200°C and a soaking time of 40 min; the rough descaling pressure is 22 MPa, and the rough rolling adopts a 1+5 mode; the rough rolling stage has 4 descaling passes with a pressure of 20 MPa; the fine descaling pressure is 23 MPa, the fine rolling inlet temperature is 1040°C, and the final rolling temperature is 870°C; laminar flow cooling is achieved through front-stage cooling; the coiling adopts a front-stage high coiling tension of 45 MPa, with the high coiling tension section of the inner ring being ≥10% of the diameter, and the coiling temperature being 660°C; after the hot coiling reaches the lower limit, it enters the slow cooling pit, and the time from the line to entering the slow cooling pit is 25 min, thus obtaining the agricultural machinery steel substrate.

[0101] Based on the aforementioned steel substrate for agricultural machinery, this application also provides a method for preparing wear-resistant parts for agricultural machinery, comprising the following steps: first, the steel coil is flattened into a flat plate; the flat plate is cut into the required circle; the edges of the cut sheet are precision machined to obtain good edge quality; the precision machined sheet is heated in a tunnel furnace, which is equipped with nitrogen gas protection; the austenitization temperature in the tunnel furnace is 900℃, the plate thickness is 3.5mm, and the austenitization homogenization time is 4.5min; hot pressing quenching: after the sheet exits the tunnel furnace, it is sent to the hot pressing quenching mold by a robot arm for hot pressing quenching; shot peening and baking paint, etc.: the hot-quenched disc is shot peened to remove the surface oxide scale, and then undergoes baking paint and other processes to obtain the wear-resistant parts for agricultural machinery.

[0102] Example 2

[0103] The preparation process of the agricultural machinery steel substrate in this embodiment is as follows: KR desulfurization, converter smelting, LF refining, RH refining, and continuous casting; the continuously cast billet needs to be hot-charged, with a charging temperature of 530°C. The heating furnace is divided into a heat recovery section, a preheating section, a first-stage heating section, a second-stage heating section, and a soaking section. The heating time in the furnace is 190 minutes, a weakly reducing atmosphere is used, the soaking temperature is 1210°C, and the soaking time is 45 minutes; the rough descaling pressure is 22 MPa, and the rough rolling adopts a 1+5 mode; the rough rolling stage has 4 descaling passes with a pressure of 20 MPa; the fine descaling pressure is 23 MPa, the fine rolling inlet temperature is 1050°C, and the final rolling temperature is 880°C; laminar flow cooling is achieved through front-stage cooling; the coiling adopts a front-stage high coiling tension of 44 MPa, with the high coiling tension section of the inner ring being ≥10% of the diameter, and the coiling temperature is 650°C; after the hot coiling reaches the lower limit, it enters the slow cooling pit, and the time from the line to entering the slow cooling pit is 20 minutes, thus obtaining the agricultural machinery steel substrate.

[0104] Based on the aforementioned steel substrate for agricultural machinery, this application also provides a method for preparing wear-resistant parts for agricultural machinery, comprising the following steps: first, the steel coil is flattened into a flat plate; the flat plate is cut into the required circle; the edges of the cut sheet are precision machined to obtain good edge quality; the precision machined sheet is heated in a tunnel furnace, which is equipped with nitrogen gas protection; the austenitization temperature in the tunnel furnace is 910℃, the plate thickness is 5.5mm, and the austenitization homogenization time is 6.5min; hot pressing quenching: after the sheet exits the tunnel furnace, it is sent to the hot pressing quenching mold by a robot arm for hot pressing quenching; shot peening and baking paint, etc.: the hot-quenched disc is shot peened to remove the surface oxide scale, and then undergoes baking paint and other processes to obtain the wear-resistant parts for agricultural machinery.

[0105] Example 3

[0106] The preparation process of the agricultural machinery steel substrate in this embodiment is as follows: KR desulfurization, converter smelting, LF refining, RH refining, and continuous casting; the continuously cast billet needs to be hot-charged, with a charging temperature of 610°C. The heating furnace is divided into heat recovery section, preheating section, first heating section, second heating section, and soaking section. The heating time in the furnace is 220 min, using a weak reducing atmosphere, with a soaking temperature of 1220°C and a soaking time of 40 min; the rough descaling pressure is 22 MPa, and the rough rolling adopts a 1+5 mode; the rough rolling stage has 5 descaling passes with a pressure of 20 MPa; the fine descaling pressure is 23 MPa, the fine rolling inlet temperature is 1055°C, and the final rolling temperature is 865°C; laminar flow cooling is achieved through front-stage cooling; the coiling adopts a front-stage high coiling tension of 44 MPa, with the high coiling tension section of the inner ring being ≥10% of the diameter, and the coiling temperature is 640°C; after the hot coiling reaches the lower limit, it enters the slow cooling pit, and the time from the line to entering the slow cooling pit is 23 min, thus obtaining the agricultural machinery steel substrate.

[0107] Based on the aforementioned steel substrate for agricultural machinery, this application also provides a method for preparing wear-resistant parts for agricultural machinery, comprising the following steps: first, the steel coil is flattened into a flat plate; the flat plate is cut into the required circle; the edges of the cut sheet are precision machined to obtain good edge quality; the precision machined sheet is heated in a tunnel furnace, which is equipped with nitrogen gas protection; the austenitization temperature in the tunnel furnace is 890℃, the plate thickness is 4.5mm, and the austenitization homogenization time is 5.5min; hot pressing quenching: after the sheet exits the tunnel furnace, it is sent to the hot pressing quenching mold by a robot arm for hot pressing quenching; shot peening and baking paint, etc.: the hot-quenched disc is shot peened to remove the surface oxide scale, and then baked paint and other processes are performed to obtain the wear-resistant parts for agricultural machinery.

[0108] Comparative Example 1

[0109] The comparative example of the agricultural machinery steel substrate preparation process in this application is as follows: KR desulfurization, converter smelting, LF refining, RH refining, and continuous casting; the continuously cast billet needs to be hot-charged, with a charging temperature of 565℃. The heating furnace is divided into heat recovery section, preheating section, first heating section, second heating section, and soaking section. The heating time in the furnace is 200 min, using a weakly reducing atmosphere, with a soaking temperature of 1200℃ and a soaking time of 40 min; the rough descaling pressure is 22 MPa, and the rough rolling adopts a 1+5 mode; the rough rolling stage has 4 descaling passes with a pressure of 20 MPa; the fine descaling pressure is 23 MPa, the fine rolling inlet temperature is 1050℃, and the final rolling temperature is 875℃; laminar flow cooling is achieved through front-stage cooling; the coiling adopts a front-stage high coiling tension of 44 MPa, with the high coiling tension section of the inner ring being ≥10% of the diameter, and the coiling temperature is 665℃; after the hot coiling reaches the lower limit, it enters the slow cooling pit, and the time from the line to entering the slow cooling pit is 25 min, thus obtaining the agricultural machinery steel substrate.

[0110] Based on the aforementioned steel substrate for agricultural machinery, this application also provides a comparative example of a method for preparing wear-resistant parts for agricultural machinery, comprising the following steps: first, the steel coil is flattened into a flat plate; the flat plate is cut into the required circle; the edges of the cut sheet are precision machined to obtain good edge quality; the precision machined sheet is heated in a tunnel furnace, which is equipped with nitrogen gas protection; the austenitization temperature in the tunnel furnace is 900℃, the plate thickness is 3.5mm, and the austenitization homogenization time is 4.5min; hot pressing quenching: after the sheet exits the tunnel furnace, it is sent to the hot pressing quenching mold by a robot arm for hot pressing quenching; shot peening and baking paint, etc.: the hot-quenched disc is shot peened to remove the surface oxide scale, and then undergoes processes such as baking paint to obtain the wear-resistant parts for agricultural machinery.

[0111] Comparative Example 2

[0112] The comparative example of the agricultural machinery steel substrate preparation process in this application is as follows: KR desulfurization, converter smelting, LF refining, RH refining, and continuous casting; the continuously cast billet needs to be hot-charged, with a charging temperature of 570℃. The heating furnace is divided into heat recovery section, preheating section, first heating section, second heating section, and soaking section. The heating time in the furnace is 190 min, a weakly reducing atmosphere is used, the soaking temperature is 1210℃, and the soaking time is 40 min; the rough descaling pressure is 22 MPa, and the rough rolling adopts a 1+5 mode; the rough rolling stage has 4 descaling passes with a pressure of 20 MPa; the fine descaling pressure is 23 MPa, the fine rolling inlet temperature is 1050℃, and the final rolling temperature is 880℃; laminar flow cooling is front-stage cooling; the coiling adopts a front-stage high coiling tension of 44 MPa, with the high coiling tension section of the inner ring being ≥10% of the diameter, and the coiling temperature is 670℃; after the hot coiling reaches the lower limit, it enters the slow cooling pit, and the time from the line to entering the slow cooling pit is 27 min, thus obtaining the agricultural machinery steel substrate.

[0113] Based on the aforementioned steel substrate for agricultural machinery, this application also provides a comparative example of a method for preparing wear-resistant parts for agricultural machinery, comprising the following steps: first, the steel coil is flattened into a flat plate; the flat plate is cut into the required circle; the edges of the cut sheet are precision machined to obtain good edge quality; the precision machined sheet is heated in a tunnel furnace, which is equipped with nitrogen gas protection; the austenitization temperature in the tunnel furnace is 900℃, the plate thickness is 3.5mm, and the austenitization homogenization time is 4.5min; hot pressing quenching: after the sheet exits the tunnel furnace, it is sent to the hot pressing quenching mold by a robot arm for hot pressing quenching; shot peening and baking paint, etc.: the hot-quenched disc is shot peened to remove the surface oxide scale, and then undergoes processes such as baking paint to obtain the wear-resistant parts for agricultural machinery.

[0114] The mass fractions of the chemical composition of the agricultural machinery steel substrates of Examples 1-3 and Comparative Examples 1-2 are shown in Table 1. The mechanical properties of the agricultural machinery steel substrates and agricultural machinery wear-resistant parts of Examples 1-3 and Comparative Examples 1-2 are shown in Table 2. The hardness distribution of the agricultural machinery wear-resistant parts of Examples 1-3 and Comparative Examples 1-2 is shown in Table 3.

[0115] Table 1. Mass fraction (wt / %) of chemical composition of agricultural machinery steel substrates in Examples 1-3 and Comparative Examples 1-2

[0116]

[0117] Table 2 Mechanical properties of agricultural machinery steel base plates and wear-resistant parts of Examples 1-3 and Comparative Examples 1-2

[0118]

[0119] Table 3. Hardness distribution (HRC) of agricultural machinery wear-resistant parts in Examples 1-3 and Comparative Examples 1-2

[0120]

[0121] Figure 3 This is a schematic diagram of the location for measuring hardness provided in the embodiments and comparative examples of this application. In Table 3, hardness point 1 is... Figure 3 Position 1 in the middle, and so on, follow this pattern.

[0122] As can be seen from Tables 1, 2, and 3:

[0123] (1) The hardness distribution of the embodiments of the present invention is all within 51HRC~53HRC, and the hardness distribution is uniform;

[0124] (2) A comparison between the examples and Comparative Example 1 shows that the addition of Cu-Cr-Ni elements significantly improves the corrosion resistance of wear-resistant steel for agricultural machinery.

[0125] (3) From the comparison between the examples and Comparative Example 2, it was observed that the non-stick properties of the wear-resistant steel were improved after the Sn element was added.

[0126] Figures 4-7 Detailed explanation:

[0127] Figure 4 A metallographic image of the core of the steel substrate for agricultural machinery provided in Embodiment 1 of this application;

[0128] Figure 5 This is a metallographic image of the edge of a steel substrate for agricultural machinery provided in Embodiment 1 of this application;

[0129] Depend on Figure 4 , Figure 5 The comparison shows that the metallographic structure of the steel substrate for agricultural machinery is uniformly distributed, and the metallographic structure includes ferrite and pearlite.

[0130] Figure 6 A metallographic image of the core of the wear-resistant agricultural machinery part provided in Embodiment 1 of this application;

[0131] Figure 7 A metallographic image of the edge of the wear-resistant agricultural machinery part provided in Embodiment 1 of this application;

[0132] Depend on Figure 6 , Figure 7 The comparison shows that the metallographic structure of the wear-resistant parts of agricultural machinery is uniformly distributed and includes martensite.

[0133] Furthermore, one or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0134] In this embodiment of the invention, the obtained agricultural machinery wear-resistant parts have uniform hardness. The hardness of the parts after hot pressing and quenching is 51HRC~53HRC. The narrow range of hardness control ensures uniform wear resistance and high wear resistance.

[0135] In this embodiment of the invention, the corrosion resistance of the obtained agricultural machinery wear-resistant parts is improved by adding alloying elements and coordinating the process.

[0136] In this embodiment of the invention, the obtained agricultural machinery wear-resistant parts achieve non-stick properties through composition optimization.

[0137] In the embodiments of the invention, the obtained agricultural machinery wear-resistant parts have higher toughness. The toughness is improved through the optimization of alloying elements and process.

[0138] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An agricultural machine steel substrate characterized by, The chemical composition of the steel base plate for agricultural machinery includes, in mass fraction, C: 0.27%-0.40%, Si: 0.1%-1.2%, Mn: 0.5%-2.7%, P≤0.025%, S≤0.035%, Alt: 0.01%-0.70%, B: 0.001%-0.008%, Cu: 0.1%-1.0%, Cr: 0.1%-1.3%, Ni: 0.05%-0.3%, Mo: 0.03%-0.3%, Sn: 0.01%-0.3%, Ti: 0.01%-0.08%, and the balance of Fe and inevitable impurities. The preparation method of the steel base plate for agricultural machinery includes: obtaining a casting blank with the chemical composition; heating, rough descaling, rough rolling, fine descaling and finish rolling the casting blank to obtain a hot-rolled coil; and first cooling, coiling and second cooling the hot-rolled coil to obtain the steel base plate for agricultural machinery; wherein the inlet temperature of the finish rolling is 980-1060 DEG C, the finish rolling temperature is 860-900 DEG C, the coiling temperature is 580-700 DEG C, and the first cooling is laminar cooling; and the second cooling specifically includes: after the hot-rolled coil is discharged, the hot-rolled coil is put into a slow cooling pit, and the time from the discharge to the entry into the slow cooling pit is 15-30 minutes.

2. The steel substrate for agricultural machinery according to claim 1, characterized by, The metallographic structure of the steel substrate for agricultural machinery includes ferrite and pearlite, and the steel substrate for agricultural machinery satisfies at least one of the following properties: yield strength of 500 MPa to 650 MPa, tensile strength of 700 MPa to 800 MPa, and elongation A 50 is 15% to 25%.

3. A method of producing an agricultural machine steel substrate as claimed in claim 1 or 2, characterized by, The method includes: obtaining a casting blank with the chemical composition; heating, rough descaling, rough rolling, fine descaling and finish rolling the casting blank to obtain a hot-rolled coil; first cooling, coiling and second cooling the hot-rolled coil to obtain the steel base plate for agricultural machinery.

4. The method of claim 3, wherein, The heating, rough descaling, rough rolling, fine descaling and finish rolling of the casting blank to obtain a hot-rolled coil include: hot charging the casting blank into a heating furnace, controlling the temperature of the hot-charged casting blank to be greater than or equal to 400 DEG C and the atmosphere residual oxygen value in the heating furnace to be less than or equal to 3%, and then first heating, and controlling the first heating end temperature and the first heating holding time; second heating the casting blank after the first heating, and controlling the second heating end temperature and the second heating temperature rising time; third heating the casting blank after the second heating, and controlling the third heating end temperature and the third heating temperature rising time; fourth heating the casting blank after the third heating, and controlling the fourth heating end temperature, the fourth heating temperature rising time and the fourth heating holding time, rough descaling, rough rolling, fine descaling and finish rolling to obtain a hot-rolled coil.

5. The method of claim 4, wherein, The first heating end temperature is 600-700 DEG C, and the first heating holding time is 40-70 minutes; The second heating end temperature is 700-1100 DEG C, and the second heating temperature rising time is 10-40 minutes; The third heating end temperature is 1100-1150 DEG C, and the third heating temperature rising time is 30-50 minutes; The fourth heating end temperature is 1150-1250 DEG C, the fourth heating temperature rising time is 20-40 minutes, and the fourth heating holding time is less than or equal to 50 minutes.

6. The method of claim 4, wherein, The rough descaling pressure is 20-24 MPa; the descaling pass of rough rolling is greater than or equal to 4 passes, and the descaling pressure is 18-23 MPa; and the fine descaling pressure is 21-25 MPa.

7. The method of claim 4, wherein, The front section coiling tension is greater than or equal to 43 MPa, and the high coiling tension section of the inner ring is greater than or equal to 10% of the diameter.

8. A method of producing an agricultural machine wear part, characterized by, The method comprises: The agricultural steel substrate of claim 1 or 2 is blanked to obtain a blank; The blank is heated, then hot-pressed and quenched, and the cooling water temperature of the hot-pressing and quenching is controlled to be 35-45 DEG C to obtain an agricultural wear-resistant part.

9. The method of claim 8, wherein, The end temperature of the heating is 850-950 DEG C, and the holding time of the heating satisfies the following relationship: t = d + 1, In the formula, t represents the holding time, and d represents the thickness of the agricultural steel substrate.

10. The agricultural machine wear part produced by the method of claim 8 or 9, wherein, The metallographic structure of the agricultural wear-resistant part comprises martensite, and the agricultural wear-resistant part satisfies at least one of the following properties: the hardness is 51-53 HRC, the yield strength is 1350-1450 MPa, the tensile strength is 1750-1850 MPa, and the elongation A50 after fracture is 7-9%.

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