A Cr-Al alloyed high manganese austenitic steel and its preparation method

Abstract

The present invention discloses a Cr-Al alloyed high-manganese austenitic steel and a preparation method thereof, which belongs to the technical field of alloy steels and solves the problem in the prior art that the erosion resistance and toughness of erosion-resistant steel for dredging pipes cannot be taken into account at the same time. The components of the Cr-Al alloyed high-manganese austenitic steel include, by mass percentage, C: 0.8% to 1.5%, Mn: 10.0% to 18.0%, Cr: 2.0% to 5.0%, Al: 1.0% to 3.0%, and the remainder is Fe and unavoidable impurities. The microstructure of the finished steel plate of the steel of the present invention is a uniform austenitic structure. The steel of the present invention has excellent low-temperature toughness and excellent resistance to seawater mortar erosion.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy steels, and in particular to a Cr-Al alloyed high-manganese austenitic steel having excellent seawater mortar erosion resistance and a preparation method thereof. Background Art

[0002] The role of dredging equipment is to efficiently excavate seabed rock and soil and simultaneously transport them over long distances via pipelines, thereby enabling operations such as sand blowing and land reclamation, channel dredging, and seabed resource extraction. However, existing pipeline materials in my country are subject to severe abrasion failure under the demanding operating conditions of high concentrations, high pressures, high flow rates, and long-distance transport. The widely used carbon steels Q235B and Q355B have a lifespan of approximately one to two years in media such as silt and fine sand, but typically wear through within nine months in media containing high levels of medium-coarse sand and coral rock. Severe pipeline wear not only reduces the safety of dredging operations but also increases the cost of pipeline replacement and repair, resulting in the downtime of the entire vessel and significant economic losses. Therefore, overcoming the technical bottleneck of highly abrasion-resistant pipeline materials is of paramount importance. Summary of the Invention

[0003] In view of the above situation, the present invention aims to provide a Cr-Al alloyed high manganese austenitic steel with excellent resistance to seawater mortar erosion and a preparation method thereof, which is used to solve the following technical problems: the corrosion resistance and toughness of the existing corrosion-resistant steel for dredging pipes cannot be taken into account at the same time.

[0004] The purpose of the present invention is mainly achieved through the following technical solutions:

[0005] The invention provides a Cr-Al alloyed high manganese austenitic steel. The components of the Cr-Al alloyed high manganese austenitic steel include, by mass percentage, C: 0.8%-1.5%, Mn: 10.0%-18.0%, Cr: 2.0%-5.0%, Al: 1.0%-3.0%, and the balance is Fe and unavoidable impurities.

[0006] Furthermore, the components of the Cr-Al alloyed high manganese austenitic steel may further include one or more of the following elements, in percentage by mass: V: 0.05% to 0.30%; Ni: 0.1% to 3.0%; Mo: 0.05% to 0.4%; Si: 0.05% to 2.0%; B: 0.0005% to 0.005%; Nb: 0.02% to 0.3%; Ti: 0.05% to 0.25%; Cu: 0.20% to 2.0%; RE: 0.002% to 0.10%; and Ca: 0.005% to 0.03%.

[0007] Furthermore, the components of the Cr-Al alloyed high manganese austenitic steel may include, by mass percentage, C: 0.85% to 1.5%, Mn: 10.5% to 17.5%, Cr: 2.5% to 5.0%, Al: 1.1% to 3.0%, and the balance being Fe and unavoidable impurities.

[0008] Furthermore, the components of the Cr-Al alloyed high manganese austenitic steel may further include one or more of the following elements, which are added in percentage by mass: V: 0.06% to 0.29%; Ni: 0.1% to 3.0%; Mo: 0.05% to 0.4%; Si: 0.05% to 1.5%; B: 0.0005% to 0.004%; Nb: 0.02% to 0.25%; Ti: 0.05% to 0.2%; Cu: 0.20% to 1.5%; RE: 0.003% to 0.10%; and Ca: 0.005% to 0.025%.

[0009] The present invention also provides a method for preparing Cr-Al alloyed high manganese austenitic steel, comprising:

[0010] Step 1: smelting and pouring to obtain a casting blank or ingot;

[0011] Step 2: Forging the billet or ingot to obtain a forged billet, subjecting the forged billet to high-temperature homogenization treatment, rolling, and rapidly cooling to below 400° C. and then air-cooling to room temperature to finally obtain a finished steel plate.

[0012] Furthermore, the high-temperature homogenization treatment in step 2 includes: heating the forging blank to 1100-1200° C. in a heating furnace, and keeping the temperature at 1100-1200° C. for more than 1 hour.

[0013] Furthermore, in step 2, the rolling includes multiple rolling passes, and the reduction after rolling is controlled to be above 75%.

[0014] Furthermore, in step 2, the final rolling temperature is controlled to be 850-1000°C.

[0015] Furthermore, in step 2, during the rolling process, the thickness deformation of the latter pass is smaller than that of the previous pass.

[0016] Furthermore, in step 2, the structure of the finished steel plate is a uniform austenite structure.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] a) The steel of the present invention is designed with high carbon and high manganese and the addition of appropriate amounts of chromium and aluminum elements, and is combined with a suitable hot rolling process, so that the structure of the steel of the present invention is a single austenite structure. The steel of the present invention has excellent low-temperature toughness and excellent resistance to seawater mortar erosion.

[0019] b) The mechanical properties of the steel of the present invention are as follows: elongation ≥ 39% (e.g., 39% to 58%), -20°C Charpy impact energy KV2 ≥ 110 J (e.g., 110 to 170 J).

[0020] c) The steel of the present invention has excellent resistance to seawater mortar erosion under simulated 3.5wt% NaCl seawater acidity and 3mm quartz sand mixed slurry erosion, and the eroded surface is smoother, which is beneficial to reducing pipeline fluid resistance.

[0021] d) The preparation method of the steel of the present invention is simple and has the prospect of large-scale promotion and application.

[0022] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description or be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0024] Figure 1 This is a microstructure diagram of the steel plate of Example 1 of the present invention;

[0025] Figure 2 This is a microstructure diagram of the steel plate of Example 2 of the present invention;

[0026] Figure 3 This is a microstructure diagram of the steel plate of Example 3 of the present invention;

[0027] Figure 4 This is a microstructure diagram of the steel plate of Comparative Example 1 of the present invention;

[0028] Figure 5 The surface morphologies of the steel plates after corrosion in Example 1 and Comparative Example 2 of the present invention are shown. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used to explain the principles of the present invention together with the embodiments of the present invention.

[0030] The invention provides a Cr-Al alloyed high manganese austenitic steel. The components of the Cr-Al alloyed high manganese austenitic steel include, by mass percentage, C: 0.8%-1.5%, Mn: 10.0%-18.0%, Cr: 2.0%-5.0%, Al: 1.0%-3.0%, and the balance is Fe and unavoidable impurities.

[0031] Specifically, in order to keep the stacking fault energy of the alloy within the range of high work hardening ability of the TWIP effect, the Cr content needs to be greater than or equal to the Al content.

[0032] The following is a detailed description of the effects and dosage of the components in the present invention:

[0033] C: C increases austenite stability, making it easier to achieve a fully austenitic structure. C has a strong solid solution strengthening effect, improving the strength and hardness of steel. However, excessive C content can easily lead to the formation of large amounts of carbides, affecting plasticity and toughness. The present invention considers that a C content below 0.8% may prevent a fully austenitic structure, while a C content above 1.5% can lead to the precipitation of large amounts of carbides. Therefore, the present invention controls the C content in the steel to a range of 0.8% to 1.5%.

[0034] Mn: Mn expands the austenite phase, promoting the formation of a single austenite structure. An appropriate Mn content maintains the stacking fault energy of the austenite within a reasonable range, resulting in a higher work-hardening capacity and ductility of the steel. The present invention considers that a Mn content below 10% may not result in a fully austenitic structure and lower ductility, while a Mn content above 18% results in excessively high stacking fault energy, reducing the steel's work-hardening capacity. Therefore, the present invention controls the Mn content to a range of 10.0% to 18.0%.

[0035] Cr: Cr is a key alloying element in the steel of this invention. Solid solution Cr significantly improves the steel's corrosion resistance and reduces the stacking fault energy of austenite. The addition of an appropriate amount of Cr can adjust the stacking fault energy and enhance the work-hardening ability of austenite. Considering that a Cr content below 2% does not significantly enhance corrosion resistance, while a Cr content above 5% causes the precipitation of large amounts of Cr-containing carbides along austenite grain boundaries, degrading toughness and reducing corrosion resistance, the Cr content of this steel of this invention ranges from 2.0% to 5.0%.

[0036] Al: Al is a key alloying element in the steel of this invention. It improves the steel's resistance to seawater corrosion and, to a certain extent, inhibits carbide precipitation during hot rolling, preventing intergranular carbides from damaging the steel's toughness, ductility, and corrosion resistance. Considering that an Al content below 1.0% has little effect on improving corrosion resistance and inhibiting carbide precipitation, while an Al content above 3.0% significantly increases the austenite stacking fault energy, weakening the work hardening ability and hindering wear resistance, the Al content in this steel is preferably between 1.0% and 3.0%.

[0037] In order to further improve the comprehensive performance of the above-mentioned Cr-Al alloyed high manganese austenitic steel, the components of the above-mentioned Cr-Al alloyed high manganese austenitic steel may further be added with one or more elements selected from the following elements, which are calculated in percentage by mass: V: 0.05% to 0.30%; Ni: 0.1% to 3.0%; Mo: 0.05% to 0.4%; Si: 0.05% to 2.0%; B: 0.0005% to 0.005%; Nb: 0.02% to 0.3%; Ti: 0.05% to 0.25%; Cu: 0.20% to 2.0%; RE: 0.002% to 0.10%; Ca: 0.005% to 0.03%.

[0038] Specifically, V: 0.06% ~ 0.29%; Ni: 0.1% ~ 3.0%; Mo: 0.05% ~ 0.4%; Si: 0.05% ~ 1.5%; B: 0.0005% ~ 0.004%; Nb: 0.02% to 0.25%; Ti: 0.05% to 0.2%; Cu: 0.20% to 1.5%; RE: 0.003% to 0.10%; Ca: 0.005% to 0.025%.

[0039] The functions and proportions of the above elements are as follows:

[0040] Ni: An austenite stabilizing element and can improve atmospheric corrosion resistance, but the cost is relatively high. Taking all factors into consideration, the content should be controlled within 3.0%.

[0041] Mo: Segregates at the austenite grain boundaries, increases grain boundary bonding strength, and reduces intergranular fracture tendency. In the present invention, the Mo content is controlled at 0.05% to 0.4%.

[0042] Si: Inhibits carbide precipitation, improves corrosion resistance, and reduces stacking fault energy. However, excessive addition of silicon increases the probability of ferrite precipitation in the alloy, deteriorating the alloy's mechanical and corrosion resistance. Taking all of the above into consideration, the silicon content of the steel of this invention is within the range of 0.05% to 2.0%.

[0043] Boron (B) strongly segregates at austenite grain boundaries and other crystal defects, significantly purifying the grain boundaries and reducing intergranular fracture. Its effect is not significant below 0.0005%, and its effect increases only slightly above 0.005%. Therefore, the B content should be controlled within the 0.0005% to 0.005% range.

[0044] Nb: Through solid solution and deformation-induced precipitation, Nb (C, N) strongly influences austenite recrystallization and has a strong grain refinement effect. Above 0.3%, further grain refinement becomes less pronounced and costs increase. Therefore, the Nb content in the steel of this invention should be controlled within the range of 0.02% to 0.30%.

[0045] Ti: A strong carbonitride-forming element, it forms finely dispersed titanium carbonitrides, which refine austenite grains. The Ti content should be controlled between 0.05% and 0.25%.

[0046] Ca: Deoxidizes and desulfurizes steel, and deforms inclusions, thereby improving the toughness and ductility of steel. The content should be controlled between 0.005% and 0.03%.

[0047] RE: It purifies molten steel, denatures inclusions, and improves toughness and ductility. It also enhances corrosion resistance. The RE content should be controlled within the range of 0.002% to 0.10%. Below 0.002%, these effects are insignificant. Above 0.10%, these effects reach saturation and intermetallic compounds form, impairing toughness and ductility.

[0048] Cu: An austenite stabilizing element that also improves the corrosion resistance of steel and inhibits the precipitation of carbides along grain boundaries, thereby increasing the toughness and ductility of steel. The Cu addition range is 0.20% to 2.0%.

[0049] Nitrogen combines with microalloying elements and Al in steel to form various fine carbonitrides, which refine the grains. Solid-solution nitrogen can expand the austenite phase and has a strong solid-solution strengthening effect. The nitrogen content should be controlled within the range of 0.002% to 0.50%.

[0050] P: As an impurity element, it seriously damages the toughness and plasticity of steel. The content is controlled at P≤0.015%.

[0051] S: A harmful element in steel that adversely affects the material's plasticity and toughness. High S content easily forms long inclusions such as MnS, leading to anisotropy in the steel plate and prone to delamination and cracking. The present invention requires S: ≤ 0.010%.

[0052] In order to further improve the comprehensive properties of the above-mentioned Cr-Al alloyed high manganese austenitic steel, the components of the above-mentioned Cr-Al alloyed high manganese austenitic steel may include, by mass percentage: C: 0.85% to 1.5%, Mn: 10.5% to 17.5%, Cr: 2.5% to 5.0%, Al: 1.1% to 3.0%, and the balance is Fe and unavoidable impurities.

[0053] Specifically, the components of the above-mentioned Cr-Al alloyed high manganese austenitic steel may further be added with one or more of the following elements, which are included in percentage by mass: V: 0.06% to 0.29%; Ni: 0.1% to 3.0%; Mo: 0.05% to 0.4%; Si: 0.05% to 1.5%; B: 0.0005% to 0.004%; Nb: 0.02% to 0.25%; Ti: 0.05% to 0.2%; Cu: 0.20% to 1.5%; RE: 0.003% to 0.10%; and Ca: 0.005% to 0.025%.

[0054] The present invention also provides a method for preparing the above-mentioned Cr-Al alloyed high manganese austenitic steel, comprising:

[0055] Step 1: smelting and pouring to obtain a casting blank or ingot;

[0056] Step 2: Forging the billet or ingot to obtain a forging billet, and after high-temperature homogenization treatment, rolling the forging billet to a reduction of more than 75%, and rapidly cooling to below 400°C and then air cooling to room temperature to finally obtain a finished steel plate.

[0057] Specifically, in the above step 1, a converter, an electric furnace or an induction furnace may be used for smelting, and continuous casting may be used to produce billets or die casting may be used to produce ingots.

[0058] Specifically, during the high-temperature homogenization treatment in step 2, it is important to consider that a holding temperature that is too high may lead to overburning and affect performance, while a holding temperature that is too low may cause carbide precipitation and affect mechanical properties. A holding time that is too long may affect processing efficiency and increase energy consumption, while a holding time that is too short may make it difficult to achieve homogenization requirements. Therefore, the specific steps for controlling the high-temperature homogenization treatment in step 2 include: heating the forging blank to 1100-1200°C in a heating furnace and holding it at 1100-1200°C for at least 1 hour.

[0059] Specifically, in step 2, considering that Cr-rich carbides are more likely to precipitate between grains when the finishing rolling temperature is low, the finishing rolling temperature is controlled to be 850-1000°C.

[0060] Specifically, in the above step 2, rolling includes multiple rolling passes. Considering that too small a reduction in each pass will result in too many passes and the temperature will be difficult to control, and too large a reduction will lead to increased width and excessive rolling stress, which will increase the difficulty of forming, therefore, the reduction in each pass is controlled to be 10% to 50%.

[0061] Specifically, in the above step 2, during the rolling process, the thickness deformation of the latter pass is smaller than that of the former pass.

[0062] Specifically, in step 2 above, if the cooling rate after rolling is too slow, a large amount of carbides may be easily precipitated, affecting the plasticity and toughness. Therefore, the cooling rate of the rapid cooling is controlled to be greater than 10°C / s.

[0063] Specifically, in the above step 2, the structure of the finished steel plate is a uniform austenite structure.

[0064] Specifically, in step 2 above, the mechanical properties of the finished steel plate are as follows: elongation ≥ 39%, -20°C Charpy impact energy KV2 ≥ 110 J. The steel of the present invention has excellent low-temperature toughness.

[0065] Specifically, in the above step 2, the finished steel plate has excellent resistance to seawater mortar erosion under simulated 3.5wt% NaCl seawater acidity and 3mm quartz sand mixed slurry erosion, and the eroded surface is smoother, which is beneficial to reducing pipeline fluid resistance.

[0066] Compared with the prior art, the steel of the present invention is designed with high carbon and high manganese and the addition of appropriate amounts of chromium and aluminum elements, and is combined with a suitable hot rolling process, so that the structure of the steel of the present invention is a single austenite structure. The steel of the present invention has excellent low-temperature toughness and excellent resistance to seawater mortar erosion.

[0067] The mechanical properties of the steel of the present invention are as follows: elongation ≥ 39% (for example, 39% to 58%), and Charpy impact energy KV2 at -20°C ≥ 110J (for example, 110 to 170J).

[0068] The steel exhibits excellent resistance to seawater slurry erosion under simulated erosion conditions using a slurry mixture of 3.5wt% NaCl seawater acidity and 3mm quartz sand. The eroded surface is smoother, significantly reducing pipeline fluid resistance. For example, a test specimen was stirred in the slurry at a linear velocity of 3.28m / s (angular velocity of 150r / min) for a total travel of 5,934m (45,000 revolutions), resulting in an actual weight loss of less than 0.2g.

[0069] The preparation method of the steel of the present invention is simple and has the prospect of large-scale promotion and application.

[0070] Examples 1-6

[0071] Examples 1-6 of the present invention provide a high-manganese medium-aluminum austenitic steel and a preparation method thereof. The steels of Examples 1-6 comprise, by mass percentage, the following: C: 0.8% to 1.5%, Mn: 10.0% to 18.0%, Cr: 2.0% to 5.0%, Al: 1.0% to 3.0%, with the remainder being Fe and unavoidable impurities. The steels may further comprise: V: 0.05% to 0.30%, Ni: 0.1% to 3.0%, Mo: 0.05% to 0.4%, Si: 0.05% to 2.0%, B: 0.0005% to 0.005%, Nb: 0.02% to 0.3%, Ti: 0.05% to 0.25%, Cu: 0.20% to 2.0%, RE: 0.002% to 0.10%, and Ca: 0.005% to 0.03%.

[0072] The method for preparing the steel of Example 1 comprises:

[0073] Ingots are smelted and poured in a 100kg vacuum induction furnace, forged into 120mm (width) x 60mm (thickness) x L billets, and then cut into 150mm lengths for rolling. The rolling process includes a 3-hour hold at 1100°C, followed by rolling after removal from the furnace. After rolling, the steel is water quenched to 400°C and then air-cooled to room temperature. The rolling reduction / temperature range is 60mm-48mm, 38mm-30mm at 1000°C, 24mm-19mm at 950°C, and 15mm at 900°C. The resulting steel plate has a thickness of 15mm.

[0074] The method for preparing the steel of Example 2 comprises:

[0075] Ingots are smelted and poured in a 100kg vacuum induction furnace. These ingots are then forged into billets measuring 120mm (width) by 60mm (thickness) by L, cut into 150mm lengths, and rolled. The rolling process includes a 3-hour hold at 1200°C, followed by rolling out of the furnace, and then water quenching to room temperature. The rolling reduction / temperature profile is as follows: 60mm-48mm-(1000°C) 38mm-30mm-(950°C) 24mm-19mm-(900°C) 15mm. The resulting steel plate has a thickness of 15mm.

[0076] The method for preparing the steel of Example 3 comprises:

[0077] Ingots are smelted and poured in a 100kg vacuum induction furnace. These ingots are then forged into billets measuring 120mm (width) by 60mm (thickness) by L, cut into 150mm lengths, and rolled. The rolling process includes a 3-hour hold at 1150°C, followed by rolling and quenching to room temperature. The rolling reduction / temperature profile is as follows: 60mm-48mm-(1000°C)-38mm-30mm-(950°C)-24mm-19mm-(900°C)-15mm. The resulting steel plate has a thickness of 15mm.

[0078] The method for preparing the steel of Example 4 comprises:

[0079] Ingots are smelted and poured in a 100kg vacuum induction furnace. These ingots are then forged into billets measuring 120mm (width) by 60mm (thickness) by L, cut into 150mm lengths, and rolled. The rolling process includes a 3-hour hold at 1200°C, followed by rolling out of the furnace, and then water quenching to room temperature. The rolling reduction / temperature profile is as follows: 60mm-48mm-(1000°C) 38mm-30mm-(950°C) 24mm-19mm-(900°C) 15mm. The resulting steel plate has a thickness of 15mm.

[0080] The method for preparing the steel of Example 5 comprises:

[0081] Ingots are smelted and poured in a 100kg vacuum induction furnace. These ingots are then forged into billets measuring 120mm (width) by 60mm (thickness) by L, cut into 150mm lengths, and rolled. The rolling process includes a 3-hour hold at 1200°C, followed by rolling out of the furnace, and then water quenching to room temperature. The rolling reduction / temperature profile is as follows: 60mm-48mm-(1000°C)-38mm-30mm-(950°C)-24mm-19mm-(850°C)-15mm. The resulting steel plate has a thickness of 15mm.

[0082] The method for preparing the steel of Example 6 comprises:

[0083] Ingots are smelted and poured in a 100kg vacuum induction furnace. These ingots are then forged into billets measuring 120mm (width) by 60mm (thickness) by L, cut into 150mm lengths, and rolled. The rolling process includes a 3-hour hold at 1200°C, followed by rolling out of the furnace, and then water quenching to room temperature. The rolling reduction / temperature profile is as follows: 60mm-48mm-(1000°C)-38mm-30mm-(950°C)-24mm-19mm-(850°C)-15mm. The resulting steel plate has a thickness of 15mm.

[0084] The preparation method of the steel of Comparative Example 1 comprises:

[0085] Ingots are smelted and poured in a 100kg vacuum induction furnace. These ingots are then forged into billets measuring 120mm (width) by 60mm (thickness) by L, cut into 150mm lengths, and rolled. The rolling process includes a 3-hour hold at 1150°C, followed by rolling and subsequent water quenching to room temperature. The rolling reduction / temperature profile is as follows: 60mm-48mm, 38mm-30mm at 950°C, 24mm-19mm at 850°C, and 15mm at 800°C. The resulting steel plate has a thickness of 15mm.

[0086] The specific composition of the steel plates of Examples 1-6 is shown in Table 1 below. The microstructure of the steel plates of Examples 1-3 is shown in Table 1 below. Figure 1-Figure 3 As shown, the microstructure of the steel plate of Comparative Example 1 is as follows Figure 4 As shown. It can be seen that the microstructure of the finished steel plate is uniform austenite, and the average grain size is less than 20μm. However, the comparative example 1 with a low finishing temperature has a significantly increased amount of grain boundary carbides compared to the example 1, which greatly affects the low-temperature toughness. The mechanical properties of the steel plates of Examples 1-4 are shown in Table 2 below. The relative seawater mortar erosion resistance of the steel plates of Examples 1-6 is shown in Table 3 below. It can be seen that the steel of the present invention has a significantly improved seawater mortar erosion resistance compared to the steel of Comparative Examples 1-2.

[0087] Specifically, the relative resistance to seawater erosion of mortar is tested using a rotational motion test. This method measures the relative abrasiveness of a material by measuring the amount of metal lost as the specimen moves in a circular motion within the slurry in a mixing tank. Because this test is prone to varying operating conditions when different groups are tested, a comparative experiment is used, and the measured results are relative abrasiveness.

[0088] The composition of the erosion test medium used in the testing method is shown in Table 4: A 3.5 wt% seawater solution is used, so the water and NaCl content are fixed. The sand particle size is determined by submerging 2-4 mm sand particles, resulting in a sand weight of approximately 35 kg. This slurry composition is intended to simulate the harsh working conditions of seawater. The test specimens were agitated in the slurry at a linear velocity of 3.28 m / s (150 rpm angular velocity), with a total stroke of 5934 m (45,000 revolutions), and a total test duration of approximately 5 hours. Table 3 shows the actual weight loss and relative seawater erosion resistance of the Examples and Comparative Examples.

[0089] Figure 5 The surface morphology of the steel plates of Example 1 and Comparative Example 2 after wear (at different magnifications) is shown. At the same magnification, the area with the greatest weight loss in the Example exhibits significantly fewer pitting defects, a shallower depth, and a smoother appearance. This demonstrates that the steel of the present invention exhibits superior resistance to seawater mortar erosion.

[0090] Table 1 Main chemical components of steels of Examples and Comparative Examples (%)

[0091]

[0092]

[0093] Table 2 Mechanical properties of steels of Examples and Comparative Examples

[0094]

[0095] Table 3 Seawater mortar erosion resistance of steel in Examples and Comparative Examples

[0096]

[0097]

[0098] Table 4 Erosion test medium composition

[0099] Element Weight / g Mass fraction / % water 14000 NaCl 508 3.5 quartz sand 35000 70.7 total 49508

[0100] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A Cr-Al alloyed high manganese austenitic steel, characterized in that: The components of the Cr-Al alloyed high manganese austenitic steel include, by mass percentage, C: 1.21% to 1.5%, Mn: 10.5% to 14.17%, Cr: 3.01% to 5.0%, Al: 1.1% to 2.91%, and the balance being Fe and unavoidable impurities; In order to keep the stacking fault energy of the alloy within the range of high work hardening ability of the TWIP effect, the Cr content is greater than or equal to the Al content; The preparation method of the Cr-Al alloyed high manganese austenitic steel comprises: Step 1: smelting and pouring to obtain a casting blank or ingot; Step 2: Forging the billet or ingot to obtain a forged billet, subjecting the forged billet to a high-temperature homogenization treatment, rolling, and rapidly cooling to below 400° C. and then air-cooling to room temperature to finally obtain a finished steel plate; The high-temperature homogenization treatment in step 2 includes: heating the forging blank to 1100-1200° C. in a heating furnace and keeping the temperature at 1100-1200° C. for more than 1 hour; In step 2, during the rolling process, the thickness deformation of the subsequent pass is smaller than that of the previous pass; The structure of the finished steel plate is uniform austenite; the average grain size is less than 20μm; The mechanical properties of the steel are as follows: elongation ≥ 39%, -20℃ Charpy impact energy KV2 ≥ 110J; When steel was eroded by a simulated 3.5wt% NaCl seawater acidity and 3mm quartz sand mixed slurry, the test sample was stirred in the slurry at a linear speed of 3.28m / s, with a total stroke of 5934m and an actual weight loss of less than 0.2g.

2. The Cr-Al alloyed high manganese austenitic steel according to claim 1, characterized in that: The components of the Cr-Al alloyed high manganese austenitic steel include, by mass percentage, C: 1.21%-1.32%, Mn: 10.5%-14.17%, Cr: 3.01%-4.5%, Al: 1.42%-2.91%, and the balance is Fe and unavoidable impurities.

3. A method for preparing Cr-Al alloyed high manganese austenitic steel, characterized in that: For preparing the Cr-Al alloyed high manganese austenitic steel according to claim 1 or 2, comprising: Step 1: smelting and pouring to obtain a casting blank or ingot; Step 2: Forging the billet or ingot to obtain a forged billet, subjecting the forged billet to a high-temperature homogenization treatment, rolling, and rapidly cooling to below 400° C. and then air-cooling to room temperature to finally obtain a finished steel plate; The high-temperature homogenization treatment in step 2 includes: heating the forging blank to 1100-1200° C. in a heating furnace and keeping the temperature at 1100-1200° C. for more than 1 hour; In step 2, during the rolling process, the thickness deformation of the latter pass is smaller than that of the previous pass.

4. The preparation method according to claim 3, characterized in that In the step 2, the rolling includes multiple rolling passes, and the reduction after rolling is controlled to be more than 75%.

5. The preparation method according to claim 3, characterized in that In step 2, the final rolling temperature is controlled to be 850-1000°C.

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