10Mn medium manganese steel plate with high yield strength and high product of strength and elongation and preparation method of 10Mn medium manganese steel plate

Abstract

The invention provides a machining method for improving the yield strength and the product of high strength and elongation of a 10Mn medium manganese steel plate, and relates to the technical field of medium manganese steel. The 10Mn medium manganese steel plate with high yield strength and high product of strength and elongation is obtained through ingot casting, forging, hot rolling, warm rolling, cold rolling and tempering. The austenite grain size of the 10Mn medium manganese steel plate can reach 0.39 mu m, and the austenite content can reach 30.4%. According to the machining method, the yield strength and the product of strength and elongation of the 10Mn medium manganese steel plate can be remarkably improved under the condition that the production cost is slightly increased, the comprehensive requirements of the modern industry, especially the automobile industry, for material performance are met, and industrial production and application of medium manganese steel are promoted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medium manganese steel, and particularly relates to a processing method for improving yield strength and high strength plastic product of 10Mn medium manganese steel plate. BACKGROUND

[0002] With the rapid development of the automobile industry, the global ecological environment is deteriorating, and the requirements for automobile production are becoming higher and higher. At present, the important research direction is to improve the structural stiffness, reduce the cost, increase the safety and stability of automobile driving, and reduce the carbon emission of the automobile through the lightweight design of the automobile. The traditional steel has been unable to meet the demand of high strength, plasticity and work hardening capacity, and the medium manganese steel, one of the third generation of advanced high strength steel, has a very broad prospect in this regard. Compared with traditional high strength steel, medium manganese steel can have high strength and high ductility, bear greater deformation without easy fracture, perform excellently in special environment, can reduce cost through controlled rolling, annealing and other processes, and is compatible with traditional steel and easy to recycle, meeting the requirements of circular economy.

[0003] Medium manganese steel is an alloy steel containing 3% to 12% manganese, belonging to the third generation of advanced high strength steel (AHSS) for automobile industry, and usually has a microstructure of ferrite matrix and metastable residual austenite. The microstructure of medium manganese steel can be controlled by different heat treatment processes to obtain different phase compositions and mechanical properties.

[0004] In the manufacturing process of medium manganese steel, the addition of expensive alloys (such as nickel and molybdenum) is reduced, and the performance is adjusted by controlling the carbon and manganese content, and the manufacturing cost is reduced. The general design idea is to control the austenite content and stability in steel by carbon and manganese partitioning, and the higher the carbon and manganese content, the higher the austenite obtained is more stable, but when the carbon and manganese content exceeds a certain value, the welding performance of the steel will be deteriorated, and the more stable the austenite is, the mechanical properties will be deteriorated to some extent. Therefore, there is great limitation in relying only on carbon and manganese partitioning to control the content / stability of austenite metastable phase.

[0005] The application patent with the publication number CN 118932241 A discloses a high-carbon 8Mn medium manganese steel warm-rolled plate and its preparation method and application. The preparation method comprises the following steps: (1) melting: the ingot is melted and cast to obtain a cannonball-shaped ingot under a vacuum environment; (2) forging: the ingot is forged into a slab, and then air-cooled to room temperature; (3) hot rolling: the slab is subjected to six-pass hot rolling to obtain a thin plate, and then water-quenched to room temperature; (4) warm rolling: the thin plate is heated and kept for a period of time, and then subjected to six-pass warm rolling, and then water-quenched to room temperature; (5) post-rolling heat treatment: the thin plate after warm rolling is subjected to tempering treatment, and then water-quenched to room temperature, to obtain the high-carbon 8Mn medium manganese steel warm-rolled plate. The yield strength of the high-carbon 8Mn medium manganese steel warm-rolled plate provided in the application example is 766-789 MPa, the tensile strength is 1570-1685 MPa, the elongation is 20.6-21.3%, and the strength-plasticity product is 33.4-34.7 GPa%. Although this method can improve the strength-plasticity product and the tensile strength of the medium manganese steel plate, the yield strength of the plate is low, and the comprehensive requirements of modern industry, especially the automobile industry, on material performance cannot be met.

[0006] Increasing the yield strength of the medium manganese steel plate can realize material lightweighting under the premise of ensuring structural safety and use reliability, thereby reducing energy consumption and cost; and the high-strength-plasticity medium manganese steel plate can ensure excellent energy absorption capacity and forming performance of the material in the deformation process, which is crucial for automobile crash safety and cold forming process of complex parts. The synergistic improvement of such strength and plasticity not only can expand the application field of the medium manganese steel from automobiles to high-end markets such as buildings and mechanical manufacturing, but also can improve the market competitiveness and economic benefits of products, representing an important direction of development of advanced high-strength steel. Therefore, how to synergistically improve the yield strength and strength-plasticity product of the medium manganese steel plate without affecting the tensile strength has important significance to meet the needs of different industries for medium manganese steel. SUMMARY

[0007] Therefore, the present application provides a 10Mn medium manganese steel plate with high yield strength and high strength-plasticity product and a preparation method thereof. The present application synergistically improves the yield strength and strength-plasticity product of the medium manganese steel plate without affecting the tensile strength by hot rolling-warm rolling-cold rolling-tempering treatment of the slab, thereby meeting the needs of different industries for medium manganese steel.

[0008] The first aspect of the present application is to provide a 10Mn medium manganese steel plate with high yield strength and high strength-plasticity product, which is obtained after casting ingot, forging, hot rolling, warm rolling, cold rolling and tempering.

[0009] Preferably, the thickness of the 10Mn medium manganese steel plate with high yield strength and high strength-plasticity product is 1.2 mm.

[0010] The second aspect of the present application provides a preparation method of the 10Mn medium manganese steel plate with high yield strength and high strength plastic product, specifically comprising the following steps: S1, raw material smelting, casting, obtaining a steel ingot; S2, the steel ingot obtained in S1 is heated and kept for a certain time, then forged, air-cooled to room temperature, obtaining a slab; S3, the slab obtained in S2 is hot-rolled, warm-rolled, cold-rolled, and tempered, obtaining the 10Mn medium manganese steel plate with high yield strength and high strength plastic product.

[0011] Preferably, in the step S1, the chemical composition of the steel ingot is as follows: C 0.15wt.%-0.18wt.%, Mn 10.0wt.%-10.32wt.%, Al 1.9wt.%-2.1wt.%, the balance being Fe and inevitable impurities.

[0012] Preferably, in the step S2, the temperature of the heat preservation is 1150℃-1250℃, and the time of the heat preservation is 1.5-2 h; the cross-sectional size of the slab is 100 mm×50 mm, and the thickness is 50 mm.

[0013] Preferably, in the step S3, the hot-rolling method is as follows: the slab is heated to 1150℃-1250℃ and kept for 1.5-2 h, and then rolled, wherein the opening rolling temperature is 1200℃±50℃, the final rolling temperature is ≥900℃, and then air-cooled to room temperature; the total reduction of the hot-rolling is 90%, the pass is 9 passes, the single pass reduction is 10%, and the final hot-rolled plate thickness is 5 mm. More preferably, the final rolling temperature is 900℃-1200℃.

[0014] Preferably, in the step S3, the warm-rolling method is as follows: the thin plate obtained after hot-rolling is reheated to 500℃-600℃ and kept for 15-30 min, then immediately taken out for once warm-rolling, three-pass rolling to 3 mm, and then quickly put into a heat treatment furnace for 500℃-600℃ heat preservation for 15-30 min, and then the sample is taken out for twice warm-rolling, three-pass rolling to 1.5 mm, and air-cooled to room temperature; the total reduction of the warm-rolling is 70%, and the total pass of the warm-rolling is 6 passes.

[0015] Preferably, in the step S3, the cold-rolling method is as follows: the thin plate obtained after twice warm-rolling is cold-rolled at room temperature to obtain a cold-rolled thin plate; the reduction of the cold-rolling is 20%, the pass of the cold-rolling is 3 passes, and finally a cold-rolled plate with a thickness of 1.2 mm is obtained.

[0016] Preferably, in the step S3, the tempering method is as follows: the thin plate obtained by cold rolling is reheated to below the critical temperature Ac1 and kept for a certain time, and then water-cooled to room temperature to obtain the 10Mn medium manganese steel plate with high yield strength and high strength plastic product; the heating rate is 50-70 DEG C / s, the temperature of the keeping is 400-450 DEG C, and the keeping time is 10-15 min.

[0017] Compared with the prior art, the beneficial technical effects of the present application are: The processed 10Mn medium manganese steel plate has an austenite grain size of 0.39 mu m, an austenite content of 30.4%, and high yield strength and strength plastic product.

[0018] The present application significantly improves the yield strength and strength plastic product of the 10Mn medium manganese steel plate with a small increase in production cost, meets the comprehensive requirements of modern industry, especially the automobile industry, for material performance, and is conducive to promoting the industrialized production and application of medium manganese steel. BRIEF DESCRIPTION OF DRAWINGS

[0019] The present application will be further described below in conjunction with the drawings.

[0020] Figure 1 The electron backscattering diffraction pattern of Example 1 of the present application. DETAILED DESCRIPTION

[0021] The technical solutions of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. The raw materials used in the following embodiments of the present application are all commercially available.

[0022] Unless otherwise specified, all tests are repeated 3 times, and the results are expressed as mean ± standard deviation.

[0023] Example 1 A processing method of a 10Mn medium manganese steel plate with high yield strength and high strength plastic product, the steps are as follows: S1, melting and casting the raw materials to obtain a steel ingot; The chemical composition of the steel ingot is as follows: C 0.15wt.%, Mn 10.32wt.%, Al 2.1wt.%, and the balance of Fe and inevitable impurities; S2, heating the steel ingot to 1200 DEG C and keeping for 2 h, and then forging into a slab with a cross-sectional specification of 100 mm x 50 mm and a thickness of 50 mm, and then air cooling to room temperature; S3, hot rolling: the slab is heated to 1200 °C, and held for 2 h, and then rolled, wherein the starting rolling temperature is 1200 °C, the finishing rolling temperature is 900 °C, the reduction is 90%, and the number of rolling passes is 9, to obtain a hot-rolled plate with a thickness of 5 mm, which is then air-cooled to room temperature; warm rolling: the hot-rolled sheet is reheated to 600 °C and held for 15 min, and then immediately taken out for one warm rolling to 3 mm, wherein the reduction of the one warm rolling is 2 mm, and the number of rolling passes is three, and after the one warm rolling, the sheet is quickly placed in a heat treatment furnace for holding at 600 °C for 15 min, and then the sample is immediately taken out for two warm rolling, wherein the reduction of the two warm rolling is 1.5 mm, and the number of rolling passes is three, to obtain a warm-rolled plate with a thickness of 1.5 mm, which is air-cooled to room temperature; cold rolling: the warm-rolled sheet is cold-rolled at room temperature for 3 passes with a total reduction of 20% to obtain a cold-rolled sheet with a thickness of 1.2 mm; tempering: the cold-rolled sheet is heated to 400 °C at a heating rate of 50 °C / s, held for 10 min, and then water-cooled to room temperature to obtain a 10Mn medium-manganese steel plate with high yield strength and high strength-plastic product.

[0024] Comparative Example 1 The difference from Example 1 is that no tempering treatment is performed.

[0025] Comparative Example 2 The difference from Example 1 is that no cold rolling and tempering treatment is performed.

[0026] Comparative Example 3 The difference from Example 1 is that no cold rolling is performed, and only subsequent tempering treatment is performed.

[0027] Comparative Example 4 The difference from Example 1 is that no cold rolling is performed, and annealing treatment is used instead of tempering process, wherein the heating rate is 50 °C / s, the holding temperature is 600 °C, and the holding time is 10 min.

[0028] Comparative Example 5 The difference from Example 1 is that the total reduction of cold rolling treatment is 50%.

[0029] Comparative Example 6 The difference from Example 1 is that no warm rolling and subsequent treatment is performed.

[0030] Comparative Example 7 The steel ingot obtained in Example 1 was smelted and cast in a vacuum environment to obtain a cannonball-shaped ingot; the ingot was heated to 1200℃, and after holding for 2 h, was forged into a slab with a cross section of 100 mm x 30 mm and a thickness of 50 mm, and then air-cooled to room temperature; the slab was heated to 1200℃, and after holding for 2 h, was hot-rolled in six passes, with the starting rolling temperature being 1200℃ and the final rolling temperature being 900℃, and the reduction per pass being 14%, to obtain a thin plate with a thickness of 4 mm ± 0.4 mm, which was then water-quenched to room temperature; the hot-rolled plate was heated to 650℃, and after holding for 15 min, was warm-rolled in six passes, with the first three passes being to roll the thin plate to a thickness of 3 mm ± 0.3 mm, and then the thin plate was held at 650℃ for another 15 min, and after the holding, the last three passes were performed to finally roll the thin plate to a thickness of 2 mm ± 0.2 mm, which was then water-quenched to room temperature; the warm-rolled plate was placed in a furnace for tempering at 500℃ for 1 h, and then water-quenched to room temperature, to obtain a medium-manganese steel plate.

[0031] Comparative Example 8 The difference from Example 1 is that the chemical composition of the steel ingot is as follows: C 1.17 wt.%, Mn 8.10 wt.%, Al 5.59 wt.%, Cu 2.05 wt.%, and the balance being Fe and unavoidable impurities.

[0032] Comparative Example 9 The difference from Example 1 is that in the tempering process, the heating rate is 40℃ / s.

[0033] Comparative Example 10 The difference from Example 1 is that in the tempering process, the heating rate is 80℃ / s.

[0034] The mechanical properties of the medium-manganese steel plates obtained in Example 1 and Comparative Examples 1-10 were detected, and the results are shown in Table 1.

[0035] Table 1: Results of mechanical property detection of medium-manganese steel plates

[0036] Example 2 The difference from Example 1 is that the chemical composition of the steel ingot is as follows: C 0.15 wt.%, Mn 10.0 wt.%, Al 1.9 wt.%, and the balance being Fe and unavoidable impurities.

[0037] Example 3 The difference from Example 1 is that the chemical composition of the steel ingot is as follows: C 0.18 wt.%, Mn 10.32 wt.%, Al 2.1 wt.%, and the balance being Fe and unavoidable impurities.

[0038] Example 4 The difference from example 1 is that in the step S2, the temperature of the heat preservation is 1250℃, and the time of the heat preservation is 1.75h; the cross section size of the slab is 100mm×50mm, and the thickness is 50mm.

[0039] Example 5 The difference from example 1 is that in the step S3, the hot rolling method is as follows: the slab is heated to 1250℃, and the heat preservation time is 1.75h.

[0040] Example 6 The difference from example 1 is that in the step S3, the tempering is as follows: the cold-rolled sheet is heated to 400℃ at a heating rate of 70℃ / s, and the heat preservation time is 10min.

[0041] It is detected that the performance of the 10Mn medium manganese steel plate with high yield strength and high strength plastic product obtained in examples 2-6 has no significant difference (p>0.05) with that in example 1.

[0042] The above examples only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as the limitation of the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A 10Mn medium manganese steel plate material with high yield strength and high strength-ductility product, characterized in that, The plate material is obtained after ingot casting, forging, hot rolling, warm rolling, cold rolling and tempering.

2. The 10Mn medium manganese steel plate with high yield strength and high strength plastic product according to claim 1, characterized in that, The 10Mn medium manganese steel plate with high yield strength and high strength plastic product has a thickness of 1.2 mm.

3. The method of producing high yield strength and high strength-ductility product 10Mn medium manganese steel plate material according to claim 1 or 2, characterized in that, The method comprises the following steps: S1, raw material smelting and casting to obtain a steel ingot; S2, heating and holding the steel ingot obtained in S1 and then forging, and air cooling to room temperature to obtain a plate blank; S3, hot rolling, warm rolling, cold rolling and tempering treatment are performed on the plate blank obtained in S2 to obtain the 10Mn medium manganese steel plate with high yield strength and high strength plastic product.

4. The production method according to claim 3, characterized by, In the step S1, the chemical composition of the steel ingot is as follows: C 0.15wt.%-0.18wt.%, Mn 10.0wt.%-10.32wt.%, Al 1.9wt.%-2.1wt.%, and the balance of Fe and inevitable impurities.

5. The preparation method according to claim 3, characterized in that, In the step S2, the holding temperature is 1200℃, and the holding time is 2 h.

6. The preparation method according to claim 3, characterized in that, In the step S2, the cross-sectional size of the plate blank is 100 mm×50 mm, and the thickness is 50 mm.

7. The preparation method according to claim 3, characterized in that, In the step S3, the hot rolling method is as follows: the plate blank is heated to 1200℃ and held for 2 h, and then rolled.

8. The preparation method according to claim 3, characterized in that, In the step S3, the warm rolling method is as follows: the hot-rolled and heat-treated plate is immediately taken out for primary warm rolling, and then quickly placed in a heat treatment furnace for heating and holding, and then taken out for secondary warm rolling, and air cooled to room temperature.

9. The preparation method according to claim 3, characterized in that, In the step S3, the cold rolling method is as follows: the thin plate obtained after secondary warm rolling is cold rolled at room temperature to obtain a cold-rolled thin plate.

10. The method of claim 3, wherein, In the step S3, the tempering method is as follows: the cold-rolled thin plate is reheated to below the critical temperature Ac1 and then held, and then water cooled to room temperature to obtain the 10Mn medium manganese steel plate with high yield strength and high strength plastic product.

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