An ultra-high room temperature yield strength high manganese medium plate and a preparation method thereof

Abstract

The application discloses a kind of with super-high room temperature yield strength high manganese medium plate and preparation method thereof, belong to steel material rolling technical field.The application is with C 0.35%~0.56%, Si 0.13%~0.32%, Mn 22.7%~26.2%, Cr 3.7%~5.1%, Cu 0.41%~0.53%, Nb 0.03%~0.15%, P≤0.05%, S≤0.07%, the remainder is Fe and unavoidable impurities as component smelting, casting obtains billet, by forging modification, one-stage high-temperature hot rolling, heating after homogenization, two-stage asynchronous warm rolling, cooling, finally obtain with super-high room temperature yield strength high manganese medium plate.The high manganese medium plate of the application rolling state can be used, with super-high room temperature yield strength and good room temperature plasticity, good strength and ductility match, and alloy element is less, cost is far lower than high-alloy austenitic stainless steel.

Description

Technical Field

[0001] This invention belongs to the field of steel material rolling technology, specifically relating to a high-manganese medium-thick plate with ultra-high room temperature yield strength and its preparation method. Background Technology

[0002] Steel, as one of the most important structural materials, plays a vital role in national economic development. High-manganese austenitic steel, with its high strength, high elongation, and low cost, has broad application prospects in fields such as automobile manufacturing and low-temperature structures. However, due to its face-centered cubic crystal structure, high-manganese austenitic steel typically exhibits lower yield strength, significantly limiting its application range in structural materials.

[0003] These materials cannot be strengthened through solid-state phase transformation; their strength is primarily improved through solid solution strengthening and deformation strengthening. Increasing the carbon content within a certain range can improve yield strength through solid solution strengthening, but its effect is limited. Introducing high-density dislocations through cold deformation can also improve yield strength, but due to the limited work hardening capacity of cold-rolled samples, it often leads to a significant reduction in plasticity. Because of the significant work hardening capacity, its deformation resistance increases substantially with the amount of deformation, resulting in high energy consumption and extremely low pass rates during cold deformation, making it difficult to meet the needs of actual production.

[0004] Patent CA2100656C discloses an austenitic high-manganese steel with excellent formability, strength, and weldability, and its manufacturing method. The steel's composition (wt%) is less than 1.5% C, 15.0%–35.0% Mn, 0.1%–6.0% Al, with the remainder being Fe and other essential impurities. The austenite grain size is less than 40.0 μm, and it is obtained by adding one or more elements selected from the group consisting of less than 0.60% Si, less than 5.0% Cu, less than 1.0% Nb, less than 0.5% V, less than 0.5% Ti, less than 9.0% Cr, less than 4.0% Ni, and less than 0.2% N, ultimately yielding a high-alloy, multi-element austenitic high-manganese steel. However, this method results in lower strength, higher alloy content, increased smelting difficulty due to the introduction of nitrogen, high cost, and does not involve different asynchronous ratio rolling processes.

[0005] Patent CN115261737A discloses an air-cooled high-strength and high-toughness lightweight austenitic steel and its preparation method. This method improves performance by introducing more alloying elements and reduces the influence of cooling rate on carbide precipitation behavior during heat treatment of the austenitic lightweight steel through air cooling. However, this method has a high alloy content, low room temperature yield strength, and does not involve asynchronous warm rolling, thus limiting its application potential.

[0006] Overcoming the drawback of low yield strength in high-manganese austenitic steel will greatly enhance its engineering application prospects in automobile manufacturing and low-temperature structures. Its simple process and low cost will make it extremely promising for development. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a high-manganese medium-thick plate with ultra-high room temperature yield strength and its preparation method. It adopts the Fe-Mn-Cr-C chemical composition system and combines controlled rolling and controlled cooling processes with asynchronous warm rolling processes to fully utilize the plastic deformation capacity of high-manganese austenitic steel. This improves the strength while also obtaining good plasticity, thereby obtaining a high-manganese medium-thick plate with ultra-high room temperature yield strength.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A high-manganese medium-thick plate with ultra-high room temperature yield strength has the following chemical composition by weight percentage: C: 0.35%–0.56%, Si: 0.13%–0.32%, Mn: 22.7%–26.2%, Cr: 3.7%–5.1%, Cu: 0.41%–0.53%, Nb: 0.03%–0.15%, P: ≤0.05%, S: ≤0.07%, with the balance being Fe and unavoidable impurities.

[0010] The high-manganese medium-thick plate has a thickness of 5mm to 6mm, a room temperature yield strength of 1030MPa to 1282MPa, a room temperature tensile strength of 1139MPa to 1397MPa, and a room temperature total elongation of 20.2% to 30.1%.

[0011] The specific steps of the preparation method of the high-manganese medium-thick plate with ultra-high room temperature yield strength are as follows:

[0012] (1) According to the composition design of high manganese medium-thick plate, molten steel is smelted and cast into steel billets. The steel billets are homogenized, heated to 1200℃ and held for 5h to 6h to obtain high manganese steel ingots.

[0013] (2) The high manganese steel ingot is forged and shaped. The initial forging temperature is 1100℃~1200℃, the final forging temperature is 950℃~1100℃, the total reduction rate is 23%~25%, and the thickness of the billet after forging is 80mm~85mm.

[0014] (3) The forged and shaped steel billet is subjected to one-stage high-temperature hot rolling. The initial rolling temperature is 1050℃~1100℃, the final rolling temperature is 900℃~950℃, and the total reduction rate is 72%~88%, to obtain hot-rolled steel.

[0015] (4) Cool the hot-rolled steel to room temperature with water, then reheat it to 300℃~700℃ and keep it at that temperature for 0.5h~1.0h;

[0016] (5) After the steel billet reaches uniform temperature, it is subjected to two-stage asynchronous warm rolling with an asynchronous ratio of 1.0 to 1.3, an initial rolling temperature of 250℃ to 700℃, a final rolling temperature of 200℃ to 550℃, and a total reduction rate of 45% to 61% to obtain two-stage asynchronous warm rolled steel.

[0017] (6) The two-stage asynchronous warm-rolled steel is water-cooled to room temperature to obtain a high-manganese medium-thick plate with ultra-high room temperature yield strength.

[0018] The above-mentioned method for preparing a high-manganese medium-thick plate with ultra-high room temperature yield strength, wherein:

[0019] In step 1, the thickness of the steel billet is 100mm to 120mm.

[0020] In step 1, the steel billet is heated in an electric resistance furnace.

[0021] In step 3, the rolling process involves 5 to 7 passes, with a single pass reduction rate of 19% to 22%.

[0022] In step 3, the thickness of the hot-rolled steel is 11mm to 14mm.

[0023] In step 5, the rolling process involves 3 to 5 passes, with a single pass reduction rate of 15% to 18%.

[0024] The main idea of ​​the preparation method of the high-manganese medium-thick plate with ultra-high room temperature yield strength is as follows:

[0025] Mn has the function of stabilizing austenite, and the Mn content in this invention is controlled between 22.7% and 26.2%.

[0026] C is an austenite stabilizing element. As a major strengthening element, it can increase stacking fault energy and improve strength. The C content in this invention is controlled between 0.35% and 0.56%.

[0027] Cu is an element that expands the austenite phase region, which can stabilize austenite and improve strength. The Cu content in this invention is controlled between 0.41% and 0.53%.

[0028] Cr is an important element for obtaining corrosion resistance and can also improve strength. Therefore, the Cr content in this invention is controlled between 3.7% and 5.1%.

[0029] Nitrogen (Nb) is a strong carbide-binding element, and trace amounts of Nb can increase the strength of steel without affecting its plasticity or toughness. Furthermore, Nb has a grain-refining effect, which can improve the impact toughness of steel and lower its brittle transition temperature. Therefore, the Nb content in this invention is controlled between 0.03% and 0.15%.

[0030] Si can reduce stacking fault energy and increase strength. The Si content in this invention is controlled between 0.13% and 0.32%.

[0031] P and S tend to segregate at grain boundaries or twin boundaries, causing brittle fracture and greatly deteriorating the ultra-low temperature toughness. Therefore, they need to be controlled within a low range of P≤0.05% and S≤0.07%.

[0032] The advantages and beneficial effects of the above-mentioned high-manganese medium-thick plate with ultra-high room temperature yield strength and its preparation method compared with the prior art are as follows:

[0033] 1. The high-manganese medium-thick plate of the present invention has a simple preparation process and a wide process window. It also has ultra-high room temperature yield strength and good plasticity, which makes up for the weakness of low room temperature yield strength of austenitic steel.

[0034] 2. The high-manganese medium-thick plate of the present invention achieves a significant improvement in room temperature yield strength at a relatively low cost, is inexpensive and of high quality, and has great application and promotion value. Attached Figure Description

[0035] Figure 1 The typical asynchronous warm-rolled SEM microstructure of No. 2 steel prepared in Example 1 of this invention.

[0036] Figure 2 The typical asynchronous warm-rolled SEM microstructure of No. 4 steel prepared in Example 2 of this invention.

[0037] Figure 3 The typical asynchronous warm-rolled SEM microstructure of 6# steel prepared in Example 3 of this invention.

[0038] Figure 4 The typical asynchronous warm-rolled SEM microstructure of 8# steel prepared in Example 4 of this invention.

[0039] Figure 5 Typical asynchronous warm-rolled SEM microstructure of 10# steel prepared in Example 5 of this invention.

[0040] Figure 6 Typical asynchronous warm-rolled SEM microstructure of 12# steel prepared in Example 6 of this invention. Detailed Implementation

[0041] The rolling forming process of this invention is carried out on a 450mm two-roll reversible hot rolling experimental mill and an asynchronous hot rolling experimental mill.

[0042] Example 1

[0043] A high-manganese medium-thick plate with ultra-high room temperature yield strength has the following chemical composition by weight percentage: C: 0.41%, Si: 0.22%, Mn: 23.4%, Cr: 4.3%, Cu: 0.46%, Nb: 0.08%, P: 0.0056%, S: 0.0019%, with the balance being Fe and unavoidable impurities.

[0044] A method for preparing a high-manganese medium-thick plate with ultra-high room temperature yield strength, the specific steps of which are as follows:

[0045] (1) According to the composition design, the steel was vacuum melted and cast into No. 1 and No. 2 steel billets with a thickness of 110mm. The steel billets were heated to 1200℃ and held for 5h.

[0046] (2) The homogenized high manganese steel ingot is forged and shaped to obtain shaped steel. The initial forging temperature, final forging temperature, and total reduction rate are shown in Table 1, and the thickness of the hot-rolled steel is shown in Table 2.

[0047] (3) The forged and shaped No. 1 and No. 2 steel billets were subjected to one-stage high-temperature hot rolling to obtain hot-rolled steel. The rolling passes, initial rolling temperature, final rolling temperature, single-pass reduction rate, and total reduction rate are shown in Table 3, and the thickness of the hot-rolled steel is shown in Table 4.

[0048] (4) Cool the hot-rolled steel to room temperature with water, reheat it to 300°C, and hold it at that temperature for 0.5 hours;

[0049] (5) After the steel billet reaches uniform temperature, it is subjected to two-stage asynchronous warm rolling to obtain two-stage asynchronous warm rolled steel. The rolling passes, initial rolling temperature, final rolling temperature, asynchronous ratio, single-pass reduction rate, and total reduction rate are shown in Table 5. The thickness of asynchronous warm rolled steel is shown in Table 6.

[0050] (6) Asynchronous warm-rolled steel is water-cooled to room temperature to obtain high-manganese medium-thick plate with ultra-high room temperature yield strength.

[0051] Table 1 Forging and Shaping Process Parameters

[0052] #1 steel 1177 1083 23 #2 steel 1175 1076 24

[0053] Table 2 Thickness of Shaped Steel

[0054] Thickness of shaped steel / mm 84 82

[0055] Table 3. Process parameters for one-stage hot rolling

[0056]

[0057] Table 4 Thickness of Hot-Rolled Steel

[0058] Hot-rolled steel thickness / mm 12.5 13.5

[0059] Table 5 Asynchronous Warm Rolling Process Parameters

[0060]

[0061] Table 6 Thickness of Asynchronous Warm Rolled Steel

[0062]

[0063] Tensile specimens were taken along the rolling direction from the high-manganese medium-thick plate with ultra-high room temperature yield strength prepared in this embodiment. The room temperature tensile strengths are shown in Table 7.

[0064] Table 7. Tensile strength, yield strength, and elongation at room temperature

[0065]

[0066] The results of the examples show that the high-manganese medium-thick plate of the present invention, using controlled rolling and controlled cooling processes and asynchronous warm rolling processes, can achieve ultra-high room temperature yield strength and good plasticity in the warm-rolled high-manganese medium-thick plate while taking into account the simplicity and low cost of the process. Typical SEM microstructure of #2 steel in the asynchronous warm-rolled state is shown in the figure. Figure 1 As shown.

[0067] Example 2

[0068] A high-manganese medium-thick plate with ultra-high room temperature yield strength has the following chemical composition by weight percentage: C: 0.43%, Si: 0.19%, Mn: 23.9%, Cr: 4.1%, Cu: 0.51%, Nb: 0.1%, P: 0.0048%, S: 0.0015%, with the balance being Fe and unavoidable impurities.

[0069] A method for preparing a high-manganese medium-thick plate with ultra-high room temperature yield strength, the specific steps of which are as follows:

[0070] (1) According to the composition design, the steel was vacuum melted and cast into No. 3 and No. 4 steel billets with a thickness of 115mm. The steel billets were heated to 1200℃ and held for 6h.

[0071] (2) The homogenized high manganese steel ingot is forged and shaped to obtain shaped steel. The initial forging temperature, final forging temperature, and total reduction rate are shown in Table 8, and the thickness of the hot-rolled steel is shown in Table 9.

[0072] (3) The forged and shaped No. 3 and No. 4 steel billets were subjected to one-stage high-temperature hot rolling to obtain hot-rolled steel. The rolling passes, initial rolling temperature, final rolling temperature, single-pass reduction rate, and total reduction rate are shown in Table 10, and the thickness of the hot-rolled steel is shown in Table 11.

[0073] (4) Cool the hot-rolled steel to room temperature with water, reheat it to 400°C, and hold it at that temperature for 0.5 hours;

[0074] (5) After the steel billet reaches uniform temperature, it is subjected to two-stage asynchronous warm rolling to obtain two-stage asynchronous warm rolled steel. The rolling passes, initial rolling temperature, final rolling temperature, asynchronous ratio, single-pass reduction rate, and total reduction rate are shown in Table 12, and the thickness of asynchronous warm rolled steel is shown in Table 13.

[0075] (6) Asynchronous warm-rolled steel is water-cooled to room temperature to obtain high-manganese medium-thick plate with ultra-high room temperature yield strength.

[0076] Table 8 Forging and Shaping Process Parameters

[0077] #3 steel 1180 1068 23 #4 steel 1183 1061 24

[0078] Table 9 Thickness of Shaped Steel

[0079] Thickness of shaped steel / mm 85 84

[0080] Table 10. First-stage hot rolling process parameters

[0081]

[0082]

[0083] Table 11 Thickness of Hot-Rolled Steel

[0084] Hot-rolled steel thickness / mm 12 13

[0085] Table 12 Asynchronous Warm Rolling Process Parameters

[0086]

[0087] Table 13 Thickness of Asynchronous Warm Rolled Steel

[0088]

[0089] Tensile specimens were taken along the rolling direction from the high-manganese medium-thick plate with ultra-high room temperature yield strength prepared in this embodiment. The room temperature tensile strengths are shown in Table 14.

[0090] Table 14 Tensile strength, yield strength and elongation at room temperature

[0091]

[0092] The results of the examples show that the high-manganese medium-thick plate of the present invention, using controlled rolling and controlled cooling processes and asynchronous warm rolling processes, can achieve ultra-high room temperature yield strength and good plasticity in the warm-rolled high-manganese medium-thick plate while taking into account the simplicity and low cost of the process. Typical asynchronous warm-rolled SEM microstructure of No. 4 steel is shown in the following figure. Figure 2 As shown.

[0093] Example 3

[0094] A high-manganese medium-thick plate with ultra-high room temperature yield strength has the following chemical composition by weight percentage: C: 0.45%, Si: 0.17%, Mn: 24.1%, Cr: 4.3%, Cu: 0.46%, Nb: 0.07%, P: 0.0051%, S: 0.0021%, with the balance being Fe and unavoidable impurities.

[0095] A method for preparing a high-manganese medium-thick plate with ultra-high room temperature yield strength, the specific steps of which are as follows:

[0096] (1) According to the composition design, the steel was vacuum melted and cast into No. 5 and No. 6 steel billets with a thickness of 115mm. The steel billets were heated to 1200℃ and held for 6h.

[0097] (2) The homogenized high manganese steel ingot is forged and shaped to obtain shaped steel. The initial forging temperature, final forging temperature, and total reduction rate are shown in Table 15, and the thickness of the hot-rolled steel is shown in Table 16.

[0098] (3) The forged and shaped No. 5 and No. 6 steel billets were subjected to one-stage high-temperature hot rolling to obtain hot-rolled steel. The rolling passes, initial rolling temperature, final rolling temperature, single-pass reduction rate, and total reduction rate are shown in Table 17, and the thickness of the hot-rolled steel is shown in Table 18.

[0099] (4) Cool the hot-rolled steel to room temperature with water, reheat it to 400°C, and hold it at that temperature for 0.5 hours;

[0100] (5) After the steel billet reaches uniform temperature, it is subjected to two-stage asynchronous warm rolling to obtain two-stage asynchronous warm rolled steel. The rolling passes, initial rolling temperature, final rolling temperature, asynchronous ratio, single-pass reduction rate, and total reduction rate are shown in Table 19, and the thickness of asynchronous warm rolled steel is shown in Table 20.

[0101] (6) Asynchronous warm-rolled steel is water-cooled to room temperature to obtain high-manganese medium-thick plate with ultra-high room temperature yield strength.

[0102] Table 15 Forging and Shaping Process Parameters

[0103] 5# steel 1181 1064 24 6# steel 1178 1059 25

[0104] Table 16 Thickness of Shaped Steel

[0105] Thickness of shaped steel / mm 84 83

[0106] Table 17. Process parameters for one-stage hot rolling

[0107]

[0108] Table 18 Thickness of Hot-Rolled Steel

[0109] Hot-rolled steel thickness / mm 13 12.5

[0110] Table 19 Asynchronous Warm Rolling Process Parameters

[0111]

[0112] Table 20 Thickness of Asynchronous Warm Rolled Steel

[0113]

[0114] Tensile specimens were taken along the rolling direction from the high-manganese medium-thick plate with ultra-high room temperature yield strength prepared in this embodiment. The room temperature tensile strengths are shown in Table 21.

[0115] Table 21 Tensile strength, yield strength and elongation at room temperature

[0116]

[0117]

[0118] The results of the examples show that the high-manganese medium-thick plate of the present invention, using controlled rolling and controlled cooling processes and asynchronous warm rolling processes, can achieve ultra-high room temperature yield strength and good plasticity in the warm-rolled high-manganese medium-thick plate while taking into account the simplicity and low cost of the process. Typical asynchronous warm-rolled SEM microstructure of No. 6 steel is shown in the following figure. Figure 3 As shown.

[0119] Example 4

[0120] A high-manganese medium-thick plate with ultra-high room temperature yield strength has the following chemical composition by weight percentage: C: 0.43%, Si: 0.18%, Mn: 24.2%, Cr: 4.4%, Cu: 0.48%, Nb: 0.06%, P: 0.0044%, S: 0.0022%, with the balance being Fe and unavoidable impurities.

[0121] A method for preparing a high-manganese medium-thick plate with ultra-high room temperature yield strength, the specific steps of which are as follows:

[0122] (1) According to the composition design, the steel was vacuum melted and cast into No. 7 and No. 8 steel billets with a thickness of 105mm. The steel billets were heated to 1200℃ and held for 6h.

[0123] (2) The homogenized high manganese steel ingot is forged and shaped to obtain shaped steel. The initial forging temperature, final forging temperature, and total reduction rate are shown in Table 22, and the thickness of the hot-rolled steel is shown in Table 23.

[0124] (3) The forged and shaped No. 7 and No. 8 steel billets were subjected to one-stage high-temperature hot rolling to obtain hot-rolled steel. The rolling passes, initial rolling temperature, final rolling temperature, single-pass reduction rate, and total reduction rate are shown in Table 24, and the thickness of the hot-rolled steel is shown in Table 25.

[0125] (4) Cool the hot-rolled steel to room temperature with water, reheat it to 500°C, and hold it at that temperature for 0.5 hours;

[0126] (5) After the steel billet reaches uniform temperature, it is subjected to two-stage asynchronous warm rolling to obtain two-stage asynchronous warm rolled steel. The rolling passes, initial rolling temperature, final rolling temperature, asynchronous ratio, single-pass reduction rate, and total reduction rate are shown in Table 26, and the thickness of asynchronous warm rolled steel is shown in Table 27.

[0127] (6) Asynchronous warm-rolled steel is water-cooled to room temperature to obtain high-manganese medium-thick plate with ultra-high room temperature yield strength.

[0128] Table 22 Forging and Shaping Process Parameters

[0129] 7# steel 1175 1069 24 8# steel 1186 1072 25

[0130] Table 23 Thickness of Shaped Steel

[0131] Thickness of shaped steel / mm 83.5 82.5

[0132] Table 24. First-stage hot rolling process parameters

[0133]

[0134]

[0135] Table 25 Thickness of Hot-Rolled Steel

[0136] Hot-rolled steel thickness / mm 13 12.5

[0137] Table 26 Asynchronous Warm Rolling Process Parameters

[0138]

[0139] Table 27 Thickness of Asynchronous Warm Rolled Steel

[0140]

[0141] Tensile specimens were taken along the rolling direction from the high-manganese medium-thick plate with ultra-high room temperature yield strength prepared in this embodiment. The room temperature tensile strength is shown in Table 28.

[0142] Table 28 Tensile strength, yield strength, and elongation at room temperature

[0143]

[0144] The results of the examples show that the high-manganese medium-thick plate of the present invention, using controlled rolling and controlled cooling processes and asynchronous warm rolling processes, can achieve ultra-high room temperature yield strength and good plasticity in the warm-rolled high-manganese medium-thick plate while taking into account the simplicity and low cost of the process. Typical asynchronous warm-rolled SEM microstructure of No. 8 steel is shown in the following figure. Figure 4 As shown.

[0145] Example 5

[0146] A high-manganese medium-thick plate with excellent ultra-low temperature strength and toughness has the following chemical composition by weight percentage: C: 0.44%, Si: 0.22%, Mn: 24.2%, Cr: 4.4%, Cu: 0.48%, Nb: 0.12%, P: 0.0057%, S: 0.0020%, with the balance being Fe and unavoidable impurities.

[0147] A method for preparing a high-manganese medium-thick plate with ultra-high room temperature yield strength, the specific steps of which are as follows:

[0148] (1) According to the composition design, the steel was vacuum melted and cast into No. 9 and No. 10 steel billets with a thickness of 105mm. The steel billets were heated to 1200℃ and held for 5h.

[0149] (2) The homogenized high manganese steel ingot is forged and shaped to obtain shaped steel. The initial forging temperature, final forging temperature, and total reduction rate are shown in Table 29, and the thickness of the hot-rolled steel is shown in Table 30.

[0150] (3) The forged and shaped 9# and 10# steel billets were subjected to one-stage high-temperature hot rolling to obtain hot-rolled steel. The rolling passes, initial rolling temperature, final rolling temperature, single-pass reduction rate, and total reduction rate are shown in Table 31, and the thickness of the hot-rolled steel is shown in Table 32.

[0151] (4) Cool the hot-rolled steel to room temperature with water, reheat it to 600°C, and hold it at that temperature for 0.5 hours;

[0152] (5) After the steel billet reaches uniform temperature, it is subjected to two-stage asynchronous warm rolling to obtain two-stage asynchronous warm rolled steel. The rolling passes, initial rolling temperature, final rolling temperature, asynchronous ratio, single-pass reduction rate, and total reduction rate are shown in Table 33. The thickness of asynchronous warm rolled steel is shown in Table 34.

[0153] (6) Asynchronous warm-rolled steel is water-cooled to room temperature to obtain high-manganese medium-thick plate with ultra-high room temperature yield strength.

[0154] Table 29 Forging and Shaping Process Parameters

[0155] 9# steel 1180 1068 23 10# steel 1183 1061 24

[0156] Table 30 Thickness of Shaped Steel

[0157] Thickness of shaped steel / mm 85 84

[0158] Table 31. Process parameters for one-stage hot rolling

[0159]

[0160] Table 32 Thickness of Hot-Rolled Steel

[0161] Hot-rolled steel thickness / mm 12 12.5

[0162] Table 33 Asynchronous Warm Rolling Process Parameters

[0163]

[0164] Table 34 Thickness of Asynchronous Warm Rolled Steel

[0165]

[0166] Tensile specimens were taken along the rolling direction from the high-manganese medium-thick plate with ultra-high room temperature yield strength prepared in this embodiment. The room temperature tensile strengths are shown in Table 35.

[0167] Table 35 Tensile strength, yield strength, and elongation at room temperature

[0168]

[0169] The results of the examples show that the high-manganese medium-thick plate of the present invention, using controlled rolling and controlled cooling processes and asynchronous warm rolling processes, can achieve ultra-high room temperature yield strength and good plasticity in the warm-rolled high-manganese medium-thick plate while taking into account the simplicity and low cost of the process. Typical SEM microstructure of 10# steel in the asynchronous warm-rolled state is shown in the figure. Figure 5 As shown.

[0170] Example 6

[0171] A high-manganese medium-thick plate with excellent low-temperature strength and toughness has the following chemical composition by weight percentage: C: 0.42%, Si: 0.19%, Mn: 24.1%, Cr: 4.2%, Cu: 0.46%, Nb: 0.09%, P: 0.0047%, S: 0.0026%, with the balance being Fe and unavoidable impurities.

[0172] A method for preparing a high-manganese medium-thick plate with ultra-high room temperature yield strength, the specific steps of which are as follows:

[0173] (1) According to the composition design, the steel was vacuum melted and cast into No. 11 and No. 12 steel billets with a thickness of 105mm. The steel billets were heated to 1200℃ and held for 5h.

[0174] (2) The homogenized high manganese steel ingot is forged and shaped to obtain shaped steel. The initial forging temperature, final forging temperature, and total reduction rate are shown in Table 36, and the thickness of the hot-rolled steel is shown in Table 37.

[0175] (3) The forged and shaped 11# and 12# steel billets were subjected to one-stage high-temperature hot rolling to obtain hot-rolled steel. The rolling passes, initial rolling temperature, final rolling temperature, single-pass reduction rate, and total reduction rate are shown in Table 38, and the thickness of the hot-rolled steel is shown in Table 39.

[0176] (4) Cool the hot-rolled steel to room temperature with water, reheat it to 700°C, and hold it at that temperature for 0.5 hours;

[0177] (5) After the steel billet reaches uniform temperature, it is subjected to two-stage asynchronous warm rolling to obtain two-stage asynchronous warm rolled steel. The rolling passes, initial rolling temperature, final rolling temperature, asynchronous ratio, single-pass reduction rate, and total reduction rate are shown in Table 40, and the thickness of asynchronous warm rolled steel is shown in Table 41.

[0178] (6) Asynchronous warm-rolled steel is water-cooled to room temperature to obtain high-manganese medium-thick plate with ultra-high room temperature yield strength.

[0179] Table 36 Forging and Shaping Process Parameters

[0180] 11# steel 1189 1082 23 12# steel 1178 1076 24

[0181] Table 37 Thickness of Shaped Steel

[0182] Thickness of shaped steel / mm 83 82.5

[0183] Table 38. Process parameters for one-stage hot rolling

[0184]

[0185] Table 39 Thickness of Hot-Rolled Steel

[0186]

[0187]

[0188] Table 40 Asynchronous Warm Rolling Process Parameters

[0189]

[0190] Table 41 Thickness of Asynchronous Warm Rolled Steel

[0191]

[0192] Tensile specimens were taken along the rolling direction from the high-manganese medium-thick plate with ultra-high room temperature yield strength prepared in this embodiment. The room temperature tensile strength is shown in Table 42.

[0193] Table 42 Tensile strength, yield strength and elongation at room temperature

[0194]

[0195] The results of the examples show that the high-manganese medium-thick plate of the present invention, using controlled rolling and controlled cooling processes and asynchronous warm rolling processes, can achieve ultra-high room temperature yield strength and good plasticity in the warm-rolled high-manganese medium-thick plate while taking into account the simplicity and low cost of the process. Typical SEM microstructure of 12# steel in the asynchronous warm-rolled state is shown in the figure. Figure 6As shown.

Claims

1. A method for preparing a high-manganese medium-thick plate with ultra-high room temperature yield strength, characterized in that, Includes the following steps: Step 1. According to the composition design of high manganese medium-thick plate, molten steel is smelted and cast into steel billets. After homogenizing, heating and holding the steel billets, high manganese steel ingots are obtained. Step 2. Forge and shape the high-manganese steel ingot; Step 3. Perform a one-stage high-temperature hot rolling on the forged and shaped steel billet to obtain hot-rolled steel; Step 4. Cool the hot-rolled steel to room temperature with water, reheat it, and hold it at that temperature to obtain a uniformly heated steel billet; Step 5. The uniformly heated steel billet is subjected to two-stage asynchronous warm rolling to obtain two-stage asynchronous warm rolled steel. Step 6. Cool the two-stage asynchronous warm-rolled steel to room temperature to obtain a high-manganese medium-thick plate with ultra-high room temperature yield strength; The chemical composition of the high-manganese medium-thick plate, by weight percentage, is as follows: C: 0.35%–0.56%, Si: 0.13%–0.32%, Mn: 22.7%–26.2%, Cr: 3.7%–5.1%, Cu: 0.41%–0.53%, Nb: 0.03%–0.15%, P: ≤0.05%, S: ≤0.07%, with the balance being Fe and unavoidable impurities; The high-manganese medium-thick plate has a thickness of 5mm to 6mm, a room temperature yield strength of 1030MPa to 1282MPa, a room temperature tensile strength of 1139MPa to 1397MPa, and a room temperature total elongation of 20.2% to 30.1%.

2. The method for preparing a high-manganese medium-thick plate with ultra-high room temperature yield strength according to claim 1, characterized in that, In step 1, the thickness of the steel billet is 100mm to 120mm, and the steel billet is heated in an electric resistance furnace; the heating is homogenized to 1200℃, and the holding time is 5h to 6h.

3. The method for preparing a high-manganese medium-thick plate with ultra-high room temperature yield strength according to claim 1, characterized in that, In step 2, during the forging and shaping process, the initial forging temperature is 1100℃~1200℃, the final forging temperature is 950℃~1100℃, the total reduction rate is 23%~25%, and the thickness of the forged billet is 80mm~85mm.

4. The method for preparing a high-manganese medium-thick plate with ultra-high room temperature yield strength according to claim 1, characterized in that, In step 3, during the first-stage high-temperature hot rolling process, the initial rolling temperature is 1050℃~1100℃, and the final rolling temperature is 900℃~950℃; after 5~7 rolling passes, the single-pass reduction rate is 19%~22%, and the total reduction rate is 72%~88%; The thickness of hot-rolled steel is 11 mm to 14 mm.

5. The method for preparing a high-manganese medium-thick plate with ultra-high room temperature yield strength according to claim 1, characterized in that, In step 4, the temperature is reheated to 300℃~700℃ and held for 0.5h~1.0h.

6. The method for preparing a high-manganese medium-thick plate with ultra-high room temperature yield strength according to claim 1, characterized in that, In step 5, during the two-stage asynchronous warm rolling process, the asynchronous ratio is 1.0~1.3, the initial rolling temperature is 250℃~700℃, and the final rolling temperature is 200℃~550℃; after 3~5 passes of rolling, the single pass reduction rate is 15~18%, and the total reduction rate is 45~61%.

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