A high-strength support beam and a method for preparing the same

Abstract

The present invention provides a high-strength support arm beam, which includes the following elements in weight percentage: C: 3.4-3.7%, Si: 2.5-2.7%, Mn: 0.1-0.3%, P: ≤0.04%, S: ≤0.02%, Mg: 0.04-0.06%, Cu: 0.6-1.0%, and the balance is Fe and inevitable impurities. Compared with the prior art that uses cast steel materials to prepare support arm beams, it has higher fatigue performance, lower density and good casting process performance, and further reduces the weight of 7-9 kg / piece on the basis of the existing lightweight cast steel support arm beam, achieving the purpose of reducing the weight and cost of the support arm beam while meeting the reliability of the support arm beam. In addition, the present invention also provides a preparation method for a high-strength support arm beam.

Description

Technical Field

[0001] The invention relates to the field of automobile workpieces, and in particular to a high-strength support arm beam and a preparation method thereof. Background Art

[0002] As an important component of the air suspension, the support arm beam connects the airbag elastic element on the frame and the axle. When the vehicle is driving, the axle and the frame are elastically connected through the support arm beam, so as to reduce the impact caused by road conditions during driving, thereby ensuring riding comfort.

[0003] The arm beam is subjected to large forces, has a complex structure, and has a thick wall thickness (maximum wall thickness > 35mm). Currently, ductile iron and cast steel are usually used to produce arm beams. Ductile iron can significantly reduce costs, but the lightweight effect is not good; although cast steel has high mechanical properties, the casting processability of parts is poor, the fatigue strength is low, the lightweight effect is limited, and it is difficult to significantly reduce the cost of parts. Therefore, it is very meaningful to use appropriate materials and processes to reduce the cost and weight of arm beams while meeting the reliability requirements. Summary of the invention

[0004] In view of the defects existing in the prior art, the technical problem solved by the present invention is: to provide a high-strength support arm beam and a preparation method thereof, so that the prepared support arm beam can reduce the weight and cost of the support arm beam while meeting the reliability requirements.

[0005] To achieve the above objectives, on the one hand, the present invention provides a high-strength support arm beam, characterized in that it includes the following elements in weight percentage: C: 3.4-3.7%, Si: 2.5-2.7%, Mn: 0.1-0.3%, P: ≤0.04%, S: ≤0.02%, Mg: 0.04-0.06%, Cu: 0.6-1.0%, and the balance is Fe and unavoidable impurities.

[0006] Preferably, the high-strength support arm beam further includes Mo element or Ni element.

[0007] Preferably, the weight percentage of the Mo element is 0.1-0.3%.

[0008] Preferably, the weight percentage of the Ni element is 0.6% to 1.1%.

[0009] Preferably, the high-strength support arm beam also includes trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, and Te.

[0010] Preferably, the total content of the trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As and Te is ≤0.08%.

[0011] In a second aspect, the present invention further provides a method for preparing a high-strength corbel beam, the method comprising the following steps:

[0012] S1. Casting a corbel beam casting, wherein the corbel beam casting comprises the following elements in weight percentage: C: 3.4-3.7%, Si: 2.5-2.7%, Mn: 0.1-0.3%, P: ≤0.04%, S: ≤0.02%, Mg: 0.04-0.06%, Cu: 0.6-1.0%, and the balance is Fe and unavoidable impurities;

[0013] S2, heating the cooled arm beam casting to austenitizing temperature and keeping it warm;

[0014] S3, subjecting the austenitized arm beam casting to isothermal quenching treatment to obtain an isothermal quenched arm beam casting; after the isothermal quenched arm beam casting is cooled, a high-strength arm beam can be obtained.

[0015] Preferably, the austenitizing temperature is 850°C-870°C, and the holding time is 3-5h.

[0016] Preferably, the temperature of the isothermal quenching treatment is 340°C-360°C, and the quenching time is 2-4h.

[0017] Preferably, the isothermal quenching treatment is performed in a salt bath.

[0018] Preferably, the support beam casting further includes Mo element or Ni element.

[0019] Preferably, the weight percentage of the Mo element is 0.1-0.3%.

[0020] Preferably, the weight percentage of the Ni element is 0.6% to 1.1%.

[0021] Preferably, the support beam casting also includes trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, and Te.

[0022] Preferably, the total content of the trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As and Te is ≤0.08%.

[0023] Compared with the prior art, the advantages of the present invention are:

[0024] (1) The present invention adopts the following elements and composition by mass percentage: C: 3.4-3.7%, Si: 2.5-2.7%, Mn: 0.1-0.3%, P≤0.04%, S≤0.02%, Mg: 0.04-0.06%, Cu: 0.6-1.0%, and the balance is Fe and inevitable impurities to prepare the support arm beam, which has high mechanical properties and wear resistance. Compared with the prior art that uses cast steel materials to prepare the support arm beam, it has high fatigue resistance, low density and good casting process performance. On the basis of the existing lightweight cast steel support arm beam, the weight is further reduced by 7-9 kg / piece, thereby achieving the purpose of reducing the weight and cost of the support arm beam while meeting the reliability of the support arm beam.

[0025] (2) The high-strength support arm beam prepared by the present invention through controlling the chemical composition and heat treatment process measures has good hardenability, the tensile strength of the parts is ≥1100Mpa, and the elongation is ≥10%. The fatigue performance is better than that of cast steel materials, and the density is lower than that of cast steel, which can significantly reduce the weight and cost of the support arm beam parts. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In order to solve the technical problem that the conventional production of support arm beams using ductile iron and cast steel materials cannot reduce the weight and cost of the support arm beams while meeting the reliability requirements, the present invention proposes a high-strength support arm beam and a preparation method thereof, which can not only ensure that the thick parts of the support arm beam (maximum wall thickness > 35mm) can be hardened through, so that it has good mechanical properties and wear resistance, and ensure the reliability of the support arm beam, but also has a lower density and good casting process performance, thereby achieving the purpose of reducing the weight and cost of the support arm beam.

[0028] The present invention is further described in detail below by way of examples.

[0029] In a first aspect, the present invention provides a high-strength support arm beam, comprising the following elements in weight percentage: C: 3.4-3.7%, Si: 2.5-2.7%, Mn: 0.1-0.3%, P: ≤0.04%, S≤0.02%, Mg: 0.04-0.06%, Cu: 0.6-1.0%, and the balance is Fe and unavoidable impurities.

[0030] C and Si are both graphitizing elements, and the carbon equivalent (CE=C+Si / 3) is often used to represent the total effect of carbon and silicon. When the CE amount is high, graphite floating is easy to occur in the casting. When the CE amount is low, the casting is prone to shrinkage and white cast tendencies, so the CE amount should be appropriate. Increasing the C content will hinder the transformation of austenite, increase the amount of residual austenite and the carbon content, and improve the tensile strength of the casting. Increasing the Si content inhibits the precipitation of carbides during the nucleation and growth of austenite, forms fine needle-shaped ferrite, and improves the mechanical properties of the casting. Therefore, the present invention adopts high-carbon, high-silicon, and high-carbon equivalent components, controls the C content range to 3.4%-3.7%, the Si content range to 2.5%-2.7%, and the CE amount range to 4.3-4.7%, which can greatly improve the mechanical properties of the support arm beam.

[0031] The Mn element plays a role in solid solution strengthening, which is beneficial to improving the strength of the casting. However, Mn is prone to segregation and easily forms carbides at the boundaries of the eutectic groups of the casting, which deteriorates the mechanical properties. Therefore, the present invention adopts a low Mn content and controls the Mn element range to 0.1%-0.3%.

[0032] Cu is a graphitizing element, which can improve the hardenability of castings, hinder the formation of carbides, and appropriately improve the plasticity of castings.

[0033] Mg is a spheroidizing element, which promotes the formation of graphite nodules and makes the graphite nodules smaller and rounder, thereby improving the mechanical properties of the support beam. Therefore, the present invention adopts a high Mg component and controls the Mg content range to 0.04%-0.06%.

[0034] The present invention adopts the above-mentioned element composition to prepare the support arm beam. Compared with the prior art that adopts cast steel materials to prepare the support arm beam, the present invention has higher mechanical properties and wear resistance, as well as good hardenability, lower density and good casting process performance. On the basis of the existing lightweight cast steel support arm beam, the weight is further reduced by 7 to 9 kg / piece, thereby achieving the purpose of reducing the weight and cost of the support arm beam while meeting the reliability of the support arm beam.

[0035] Preferably, the high-strength support arm beam further comprises Mo element or Ni element, wherein the weight percentage of the Mo element is 0.1-0.3%; the weight percentage of the Ni element is 0.6%-1.1%.

[0036] The Mo element has a weak ability to form carbides and a weak ability to inhibit graphitization. It can significantly improve the hardenability of parts during isothermal quenching and ensure the mechanical properties of parts. Experiments show that adding the Mo element can improve the tensile strength of parts. In order to further ensure the hardenability and strength of thick and large parts while ensuring the elongation, the present invention preferably controls the Mo element within the range of 0.1%-0.3%, which can further increase the tensile strength of the support arm beam to more than 1200Mpa.

[0037] The Ni element does not form carbides with carbon, but is dissolved in the matrix, which can reduce the cross-sectional sensitivity of castings with uneven wall thickness and improve hardenability. Experiments show that the addition of the Ni element makes the performance of different parts of the arm beam more uniform and improves the elongation. Under the condition of ensuring strength, in order to further ensure the uniformity of the organizational performance and elongation of parts with large differences in wall thickness, the present invention preferably controls the Ni element content within the range of 0.6% to 1.1%, which can further increase the elongation of the arm beam to more than 12%.

[0038] Preferably, the above-mentioned high-strength support arm beam also includes trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, and Te.

[0039] Preferably, the total content of the trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As and Te is ≤0.08%.

[0040] Trace elements are inevitably introduced during the smelting process of the arm beam. Experiments show that trace impurity elements will affect the fatigue strength, elongation and hardenability of the isothermal quenched arm beam. The wall thickness of the arm beam parts is relatively thick (maximum wall thickness>35mm). In order to ensure good hardenability of the arm beam, the present invention controls the total content of trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, and Te to less than 0.08wt%.

[0041] In a second aspect, the present invention further provides a method for preparing a high-strength corbel beam, the method comprising the following steps:

[0042] S1. Casting a corbel beam casting, wherein the corbel beam casting comprises the following elements in weight percentage: C: 3.4-3.7%, Si: 2.5-2.7%, Mn: 0.1-0.3%, P: ≤0.04%, S≤0.02%, Mg: 0.04-0.06%, Cu: 0.6-1.0%, and the balance is Fe and unavoidable impurities;

[0043] S2, heating the cooled arm beam casting to austenitizing temperature and keeping it warm;

[0044] S3, subjecting the austenitized arm beam casting to isothermal quenching treatment to obtain an isothermal quenched arm beam casting; after the isothermal quenched arm beam casting is cooled, a high-strength arm beam can be obtained.

[0045] The high-strength support arm beam prepared by the present invention through controlling chemical composition and heat treatment process measures has good hardenability and fatigue performance better than cast steel materials. The tensile strength of the parts is ≥1100Mpa, the elongation is ≥10%, and the density is lower than that of cast steel, which can significantly reduce the weight and cost of the support arm beam.

[0046] Preferably, the austenitizing temperature is 850°C-870°C, and the holding time is 3-5h.

[0047] A large number of tests have shown that the ductile iron as-cast structure can be transformed into a uniform carbon-rich austenite structure by keeping it warm at austenitizing temperature for a certain period of time. The selection of the temperature depends on the Si content, carbides and their content of the casting. The austenitizing time is related to the austenitizing temperature, the wall thickness of the casting, etc. The austenitizing temperature and time have a certain influence on the hardenability and mechanical properties of the casting. The support arm beam part of the present invention is a thick and large casting, and a certain amount of alloy is added. In order to ensure its austenitizing and isothermal quenching transformation, the austenitizing temperature of the present invention is controlled within the range of 850°C-870°C, and the holding time is 3-5h.

[0048] Preferably, the temperature of the isothermal quenching treatment is 340°C-360°C, and the quenching time is 2-4h.

[0049] A large number of tests have shown that the austempering temperature and time are closely related to the part structure and chemical composition. When the austempering temperature is high, the matrix is ​​coarse acicular ferrite and high-carbon austenite, and the material toughness is good; when the austempering temperature is low, it is mainly fine acicular ferrite and a small amount of residual austenite, and the material strength is high. If the isothermal time is too short, only a small amount of austenite will precipitate, resulting in deterioration of the mechanical properties; if the isothermal time is too long, the high-carbon austenite will decompose into ordinary ferrite and carbide, causing the mechanical properties to deteriorate. The austempering time window depends on many factors such as the maximum wall thickness of the part, the austenitizing temperature and the chemical composition. The present invention controls the austempering temperature range to 340°C-360°C and the quenching time to 2-4h, which can ensure its mechanical properties.

[0050] Preferably, the isothermal quenching treatment is performed in a salt bath.

[0051] Preferably, the specific steps of casting the arm beam casting in step S1 include: mixing the raw materials according to the weight percentage of the above-mentioned chemical components, smelting them in a medium frequency furnace, pouring the molten iron into a treatment bag by a flushing method for spheroidizing and inoculating treatment, and after the treatment, introducing the material into the arm beam casting mold for pouring, and performing inoculation while pouring to obtain the arm beam casting.

[0052] Preferably, in step S1, the arm beam casting further comprises Mo element or Ni element, wherein the weight percentage of the Mo element is 0.1-0.3%; and the weight percentage of the Ni element is 0.6%-1.1%.

[0053] The Mo element has a weak ability to form carbides and a weak ability to inhibit graphitization. It can significantly improve the hardenability of parts during isothermal quenching and ensure the mechanical properties of parts. Experiments show that adding the Mo element can improve the tensile strength of parts and reduce the elongation. In order to further ensure the hardenability and strength of thick and large parts while ensuring the elongation, the present invention preferably controls the Mo element within the range of 0.1%-0.3%, which can further increase the tensile strength of the arm beam to more than 1200Mpa.

[0054] The Ni element does not form carbides with carbon, but is dissolved in the matrix, which can reduce the cross-sectional sensitivity of castings with uneven wall thickness and improve hardenability. Experiments show that the addition of the Ni element makes the performance of different parts of the arm beam more uniform and improves the elongation. Under the condition of ensuring strength, in order to further ensure the uniformity of the organizational performance and elongation of parts with large differences in wall thickness, the present invention preferably controls the Ni element content within the range of 0.6% to 1.1%, which can further increase the elongation of the arm beam to more than 12%.

[0055] Preferably, in step S1, the support beam casting also includes trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, and Te, and the total content of the trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, and Te is ≤0.08% by weight.

[0056] Trace elements are inevitably introduced during the smelting process of the arm beam. Experiments show that trace impurity elements will affect the fatigue strength, elongation and hardenability of the isothermal quenched arm beam. The wall thickness of the arm beam parts is relatively thick (maximum wall thickness>35mm). In order to ensure good hardenability of the arm beam, the present invention controls the total content of trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, and Te to less than 0.08wt%.

[0057] Preferably, the cooling method in step S3 is air cooling.

[0058] In this embodiment, the method for preparing the high-strength corbel beam specifically includes the following steps:

[0059] (1) The raw materials are mixed according to the following chemical ratio: in terms of weight percentage, the high-strength support arm beam contains the following chemical components: C: 3.4-3.7%, Si: 2.5-2.7%, Mn: 0.1-0.3%, P: ≤0.04%, S: ≤0.02%, Mg: 0.04-0.06%, Cu: 0.6-1.0%, and the balance is Fe and unavoidable impurities.

[0060] (2) Casting: The raw materials are melted into molten iron in a medium frequency furnace, and the temperature of the furnace is controlled. When the furnace is taken out, the molten iron is poured into a processing bag by a flushing method for spheroidizing and inoculating. After the spheroidizing treatment, the molten ductile iron is poured into a sand mold for casting the arm beam, and the pouring temperature is controlled to be, and inoculation is carried out while pouring. After cooling, the arm beam casting is taken out from the sand mold;

[0061] (3) Austenitization: The cooled ductile iron arm beam casting is sent to a heating furnace for austenitization treatment, and the arm beam casting is heated to a temperature in the range of 850°C-870°C for 3-5 hours;

[0062] (3) Isothermal quenching: The austenitized arm beam casting is quickly placed in a salt bath for isothermal quenching at 340°C-360°C for 2-4 hours;

[0063] (4) Machining: After isothermal quenching, the arm beam casting is taken out from the salt bath and air-cooled. The air-cooled arm beam casting is shot peened and machined.

[0064] The high-strength support arm beam and the preparation method thereof of the present invention are described below through specific embodiments.

[0065] Example 1

[0066] The present embodiment provides a method for manufacturing a high-strength support arm beam, comprising the following steps:

[0067] (1) The raw materials are mixed according to the following chemical ratio: in terms of weight percentage, the high-strength support arm beam contains the following chemical components: C: 3.61%, Si: 2.55%, Mn: 0.28%, P: 0.017%, S: 0.005%, Cu: 0.91%, Mg: 0.047%, the total content of trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, and Te is 0.058%, and the balance is Fe and unavoidable impurities.

[0068] (2) Casting: The raw materials are melted into molten iron in a medium frequency furnace, and the temperature of the furnace is controlled. When the furnace is taken out, the molten iron is poured into a processing bag by a flushing method for spheroidizing and inoculating. After the spheroidizing treatment, the molten ductile iron is poured into a sand mold for casting the arm beam, and the pouring temperature is controlled to be, and inoculation is carried out while pouring. After cooling, the arm beam casting is taken out from the sand mold;

[0069] (3) Austenitization: The cooled ductile iron arm beam casting is sent to a heating furnace for austenitization treatment, and the arm beam casting is heated to 850°C and kept at this temperature for 4 hours;

[0070] (3) Isothermal quenching: The austenitized arm beam casting is quickly placed in a salt bath for isothermal quenching at 350°C for 2 h.

[0071] (4) Machining: After isothermal quenching, the arm beam casting is taken out from the salt bath and air-cooled. The air-cooled arm beam casting is shot peened and machined.

[0072] Example 2

[0073] The present embodiment provides a method for manufacturing a high-strength support arm beam, comprising the following steps:

[0074] (1) The raw materials are mixed according to the following chemical ratio: in terms of weight percentage, the high-strength corbel beam contains the following chemical components: C: 3.42%, Si: 2.67%, Mn: 0.24%, P: 0.011%, S: 0.009%, Cu: 0.62%, Mo: 0.23%, Mg: 0.052%, the total content of trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, Te is 0.078%, and the balance is Fe and unavoidable impurities;

[0075] (2) Casting: The raw materials are melted into molten iron in a medium frequency furnace, and the temperature of the furnace is controlled. When the furnace is taken out, the molten iron is poured into a processing bag by a flushing method for spheroidizing and inoculating. After the spheroidizing treatment, the molten ductile iron is poured into a sand mold for casting the arm beam, and the pouring temperature is controlled to be, and inoculation is carried out while pouring. After cooling, the arm beam casting is taken out from the sand mold;

[0076] (3) Austenitization: The cooled ductile iron arm beam casting is sent to a heating furnace for austenitization treatment, and the arm beam casting is heated to 850°C and kept at this temperature for 4 hours;

[0077] (3) Isothermal quenching: The austenitized arm beam casting is quickly placed in a salt bath for isothermal quenching at 350°C for 2.5 h.

[0078] (4) Machining: After isothermal quenching, the arm beam casting is taken out from the salt bath and air-cooled. The air-cooled arm beam casting is shot peened and machined.

[0079] Example 3

[0080] The present embodiment provides a method for manufacturing a high-strength support arm beam, comprising the following steps:

[0081] (1) The raw materials are prepared according to the following chemical ratio: in terms of weight percentage, the high-strength corbel beam contains the following chemical components: C: 3.65%, Si: 2.53%, Mn: 0.21%, P: 0.010%, S: 0.008%, Cu: 0.62%, Ni: 0.94%, Mg: 0.055%, the total content of trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, Te is 0.072%, and the balance is Fe and unavoidable impurities;

[0082] (2) Casting: The raw materials are melted into molten iron in a medium frequency furnace, and the temperature of the furnace is controlled. When the furnace is taken out, the molten iron is poured into a processing bag by a flushing method for spheroidizing and inoculating. After the spheroidizing treatment, the molten ductile iron is poured into a sand mold for casting the arm beam, and the pouring temperature is controlled to be, and inoculation is carried out while pouring. After cooling, the arm beam casting is taken out from the sand mold;

[0083] (3) Austenitization: The cooled ductile iron arm beam casting is sent to a heating furnace for austenitization treatment, and the arm beam casting is heated to 850°C and kept at this temperature for 4 hours;

[0084] (3) Isothermal quenching: The austenitized arm beam casting is quickly placed in a salt bath for isothermal quenching at 350°C for 2.5 h.

[0085] (4) Machining: After isothermal quenching, the arm beam casting is taken out from the salt bath and air-cooled. The air-cooled arm beam casting is shot peened and machined.

[0086] Comparative Example 1

[0087] Comparative Example 1 provides a method for manufacturing a high-strength corbel beam, comprising the following steps:

[0088] (1) The raw materials are mixed according to the following chemical ratio: in terms of weight percentage, the high-strength corbel beam contains the following chemical components: C: 3.66%, Si: 2.68%, Mn: 0.23%, P: 0.019%, S: 0.010%, Cu: 0.91%, Mo: 0.50%, Mg: 0.043%, the total content of trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, Te is 0.063%, and the balance is Fe and unavoidable impurities;

[0089] (2) Casting: The raw materials are melted into molten iron in a medium frequency furnace, and the temperature of the furnace is controlled. When the furnace is taken out, the molten iron is poured into a processing bag by a flushing method for spheroidizing and inoculating. After the spheroidizing treatment, the molten ductile iron is poured into a sand mold for casting the arm beam, and the pouring temperature is controlled to be, and inoculation is carried out while pouring. After cooling, the arm beam casting is taken out from the sand mold;

[0090] (3) Austenitization: The cooled ductile iron arm beam casting is sent to a heating furnace for austenitization treatment, and the arm beam casting is heated to 850°C and kept at this temperature for 4 hours;

[0091] (3) Isothermal quenching: The austenitized arm beam casting is quickly placed in a salt bath for isothermal quenching at 350°C for 2.5 h.

[0092] (4) Machining: After isothermal quenching, the arm beam casting is taken out from the salt bath and air-cooled. The air-cooled arm beam casting is shot peened and machined.

[0093] Comparative Example 2

[0094] Comparative Example 2 provides a method for manufacturing a high-strength corbel beam, comprising the following steps:

[0095] (1) The raw materials are prepared according to the following chemical ratio: in terms of weight percentage, the high-strength corbel beam contains the following chemical components: C: 3.48%, Si: 2.60%, Mn: 0.22%, P: 0.011%, S: 0.009%, Cu: 0.51%, Mg: 0.059%, the total content of trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, and Te is 0.068%, and the balance is Fe and unavoidable impurities;

[0096] (2) Casting: The raw materials are melted into molten iron in a medium frequency furnace, and the temperature of the furnace is controlled. When the furnace is taken out, the molten iron is poured into a processing bag by a flushing method for spheroidizing and inoculating. After the spheroidizing treatment, the molten ductile iron is poured into a sand mold for casting the arm beam, and the pouring temperature is controlled to be, and inoculation is carried out while pouring. After cooling, the arm beam casting is taken out from the sand mold;

[0097] (3) Austenitization: The cooled ductile iron arm beam casting is sent to a heating furnace for austenitization treatment, and the arm beam casting is heated to 850°C and kept at this temperature for 4 hours;

[0098] (3) Isothermal quenching: The austenitized arm beam casting is quickly placed in a salt bath for isothermal quenching at 350°C for 2 h.

[0099] (4) Machining: After isothermal quenching, the arm beam casting is taken out from the salt bath and air-cooled. The air-cooled arm beam casting is shot peened and machined.

[0100] Comparative Example 3

[0101] Comparative Example 3 provides a method for manufacturing a high-strength corbel beam, comprising the following steps:

[0102] (1) The raw materials are prepared according to the following chemical ratio: in terms of weight percentage, the high-strength corbel beam contains the following chemical components: C: 3.61%, Si: 2.55%, Mn: 0.28%, P: 0.017%, S: 0.005%, Cu: 0.91%, Mg: 0.047%, the total content of trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, Te is 0.058%, and the balance is Fe and unavoidable impurities;

[0103] (2) Casting: The raw materials are melted into molten iron in a medium frequency furnace, and the temperature of the furnace is controlled. When the furnace is taken out, the molten iron is poured into a processing bag by a flushing method for spheroidizing and inoculating. After the spheroidizing treatment, the molten ductile iron is poured into a sand mold for casting the arm beam, and the pouring temperature is controlled to be, and inoculation is carried out while pouring. After cooling, the arm beam casting is taken out from the sand mold;

[0104] (3) Austenitization: The cooled ductile iron arm beam casting is sent to a heating furnace for austenitization treatment, and the arm beam casting is heated to 850°C and kept at this temperature for 4 hours;

[0105] (3) Isothermal quenching: The austenitized arm beam casting is quickly placed in a salt bath for isothermal quenching at 350°C for 1.5 h.

[0106] (4) Machining: After isothermal quenching, the arm beam casting is taken out from the salt bath and air-cooled. The air-cooled arm beam casting is shot peened and machined.

[0107] Comparative Example 4

[0108] Comparative Example 4 provides a method for manufacturing a high-strength corbel beam, comprising the following steps:

[0109] (1) The raw materials are prepared according to the following chemical ratio: in terms of weight percentage, the high-strength corbel beam contains the following chemical components: C: 3.58%, Si: 2.59%, Mn: 0.24%, P: 0.016%, S: 0.007%, Cu: 0.93%, Mg: 0.051%, the total content of trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, and Te is 0.131%, and the balance is Fe and unavoidable impurities;

[0110] (2) Casting: The raw materials are melted into molten iron in a medium frequency furnace, and the temperature of the furnace is controlled. When the furnace is taken out, the molten iron is poured into a processing bag by a flushing method for spheroidizing and inoculating. After the spheroidizing treatment, the molten ductile iron is poured into a sand mold for casting the arm beam, and the pouring temperature is controlled to be, and inoculation is carried out while pouring. After cooling, the arm beam casting is taken out from the sand mold;

[0111] (3) Austenitization: The cooled ductile iron arm beam casting is sent to a heating furnace for austenitization treatment, and the arm beam casting is heated to 850°C and kept at this temperature for 4 hours;

[0112] (3) Isothermal quenching: The austenitized arm beam casting is quickly placed in a salt bath for isothermal quenching at 350°C for 2 h.

[0113] (4) Machining: After isothermal quenching, the arm beam casting is taken out from the salt bath and air-cooled. The air-cooled arm beam casting is shot peened and machined.

[0114] Comparative Example 5

[0115] Comparative Example 5 provides a method for manufacturing a high-strength corbel beam, comprising the following steps:

[0116] (1) The raw materials are prepared according to the following chemical ratio: in terms of weight percentage, the high-strength corbel beam contains the following chemical components: C: 3.60%, Si: 2.55%, Mn: 0.19%, P: 0.015%, S: 0.008%, Cu: 0.66%, Ni: 1.28%, Mg: 0.050%, the total content of trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, Te is 0.063%, and the balance is Fe and unavoidable impurities;

[0117] (2) Casting: The raw materials are melted into molten iron in a medium frequency furnace, and the temperature of the furnace is controlled. When the furnace is taken out, the molten iron is poured into a processing bag by a flushing method for spheroidizing and inoculating. After the spheroidizing treatment, the molten ductile iron is poured into a sand mold for casting the arm beam, and the pouring temperature is controlled to be, and inoculation is carried out while pouring. After cooling, the arm beam casting is taken out from the sand mold;

[0118] (3) Austenitization: The cooled ductile iron arm beam casting is sent to a heating furnace for austenitization treatment, and the arm beam casting is heated to 850°C and kept at this temperature for 4 hours;

[0119] (3) Isothermal quenching: The austenitized arm beam casting is quickly placed in a salt bath for isothermal quenching at 350°C for 2.5 h.

[0120] (4) Machining: After isothermal quenching, the arm beam casting is taken out from the salt bath and air-cooled. The air-cooled arm beam casting is shot peened and machined.

[0121] The elemental compositions and heat treatment process parameters of Examples 1 to 3 and Comparative Examples 1 to 5 are specifically shown in Table 1:

[0122] Table 1 Elemental composition and heat treatment process parameters of Examples 1 to 3 and Comparative Examples 1 to 5

[0123]

[0124] The mechanical properties of the support beams prepared in Examples 1 to 3 and Comparative Examples 1 to 5 were tested, and the specific results are shown in Table 2:

[0125] Table 2 Mechanical properties test results of different embodiments and comparative examples

[0126]

[0127] Note: The size of the thick part is: 38mm*45mm*60mm

[0128] It can be seen from the data of Examples 1 to 3 that the Mo element of the present application can greatly improve the tensile strength of the support arm beam; and the Ni element can greatly improve the elongation of the support arm beam while ensuring the tensile strength.

[0129] From the comparison between Example 2 and Comparative Example 1, it can be seen that controlling the Mo element to 0.1-0.3% can improve the tensile strength and elongation of the support beam.

[0130] From the comparison between Example 1 and Comparative Example 2, it can be seen that controlling the Cu element to 0.6-1.0% can improve the tensile strength and elongation of the support arm beam, and at the same time improve the hardenability of the support arm beam.

[0131] From Example 1 and Comparative Example 3, materials cast from the same furnace of molten iron are subjected to heat treatment with different processes. Through comparison, it can be seen that the tensile strength and elongation of the support arm beam can be improved by controlling the heat treatment process measures, and the hardenability of the support arm beam can be improved.

[0132] From the comparison between Example 1 and Comparative Example 4, it can be seen that the present invention controls the total content of trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, and Te to less than 0.08wt% to ensure good hardenability of the support arm beam.

[0133] From the comparison between Example 3 and Comparative Example 5, it can be seen that controlling the Ni content to 0.6-1.1% can improve the elongation of the support beam, and further increasing the Ni content will not further improve the elongation and will increase the material cost.

[0134] Comparative Example 6

[0135] The support arm beam is made of lightweight cast steel ZGD840-1030, which is a common cast steel material in the art.

[0136] The high-strength support arm beam prepared in Example 1 and the support arm beam of Comparative Example 6 were subjected to bench tests, and the test results obtained are shown in Table 3.

[0137] Table 3 Test results of the support beam bench of Example 1 and Comparative Example 6

[0138]

[0139] It can be seen from the comparison between Example 1 and Comparative Example 6 that, compared with the support arm beam made of cast steel material, the high-strength support arm beam prepared by the present invention not only has higher reliability, but also can greatly reduce quality and cost.

[0140] It should be noted that, in the present invention, relational terms such as "first" and "second" are only used 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. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0141] Furthermore, the present invention is not limited to the above-mentioned embodiments. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention. Contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A method for preparing a high-strength corbel beam, characterized in that: The preparation method comprises the following steps: S1. Casting a corbel beam casting, wherein the corbel beam casting is composed of the following elements in weight percentage: C: 3.4-3.7%, Si: 2.5-2.7%, Mn: 0.1-0.3%, P: ≤0.04%, S: ≤0.02%, Mg: 0.04-0.06%, Cu: 0.6-1.0%, Ni: 0.6-1.1%, and the balance is Fe and unavoidable impurities; the high-strength corbel beam also includes trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, Te; the total content of the trace elements Sn, Cr, V, Ti, Pb, B, Bi, Sb, Al, As, Te is ≤0.08%; S2, heating the cooled arm beam casting to austenitizing temperature and keeping it warm; S3, subjecting the austenitized arm beam casting to isothermal quenching treatment to obtain an isothermal quenched arm beam casting; after the isothermal quenched arm beam casting is cooled, a high-strength arm beam can be obtained; The austenitizing temperature is 850°C-870°C, and the holding time is 3-5h; The temperature of the isothermal quenching treatment is 340°C-360°C, and the quenching time is 2-4h; The isothermal quenching treatment is carried out in a salt bath; The maximum wall thickness of the corbel beam is greater than 35 mm; The tensile strength of the support beam is ≥1100MPa and the elongation is ≥12%.

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