AU2020455074A1 - 800 MPa construction machinery medium-manganese medium-thickness steel and manufacturing method therefor - Google Patents
800 MPa construction machinery medium-manganese medium-thickness steel and manufacturing method therefor Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 120
- 239000010959 steel Substances 0.000 title claims abstract description 120
- 239000011572 manganese Substances 0.000 title claims abstract description 50
- 229910052748 manganese Inorganic materials 0.000 title claims abstract description 40
- 238000010276 construction Methods 0.000 title claims abstract description 30
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 21
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 24
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 12
- 239000012535 impurity Substances 0.000 claims abstract description 10
- 239000000126 substance Substances 0.000 claims abstract description 10
- 238000003723 Smelting Methods 0.000 claims abstract description 7
- 229910052742 iron Inorganic materials 0.000 claims abstract description 7
- 238000005096 rolling process Methods 0.000 claims description 43
- 238000010438 heat treatment Methods 0.000 claims description 18
- 238000005496 tempering Methods 0.000 claims description 18
- 238000001816 cooling Methods 0.000 claims description 17
- 239000000203 mixture Substances 0.000 claims description 13
- 238000009847 ladle furnace Methods 0.000 claims description 9
- 238000005275 alloying Methods 0.000 claims description 7
- 238000005266 casting Methods 0.000 claims description 5
- 238000009749 continuous casting Methods 0.000 claims description 5
- 230000007547 defect Effects 0.000 claims description 5
- 238000006477 desulfuration reaction Methods 0.000 claims description 5
- 230000023556 desulfurization Effects 0.000 claims description 5
- 238000007670 refining Methods 0.000 claims description 5
- 238000002791 soaking Methods 0.000 claims description 4
- 238000004140 cleaning Methods 0.000 claims description 2
- 229910000797 Ultra-high-strength steel Inorganic materials 0.000 abstract description 3
- 239000000470 constituent Substances 0.000 abstract 1
- 229910001566 austenite Inorganic materials 0.000 description 13
- 229910000734 martensite Inorganic materials 0.000 description 12
- 238000005728 strengthening Methods 0.000 description 5
- 229910000746 Structural steel Inorganic materials 0.000 description 4
- 238000013461 design Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 239000006104 solid solution Substances 0.000 description 3
- 229910000617 Mangalloy Inorganic materials 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000002708 enhancing effect Effects 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229910001182 Mo alloy Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000000844 transformation Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000009489 vacuum treatment Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
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- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
- Metal Rolling (AREA)
Abstract
An 800 MPa construction machinery medium-manganese medium-thickness steel and a manufacturing method therefor, relating to the technical field of steel and iron smelting, wherein the chemical constituents and the mass percentages thereof are as follows: C: 0.05-0.08%, Mn: 4.8-5.8%, Si: 0.10-0.35%, P≤0.010%, S≤0.003%, Ti: 0.01-0.05%, Ni + Cr + Mo: 0.7-1.2%, with the balance being Fe and inevitable impurities. The medium-thickness steel can achieve excellent core mechanical properties that common 800 MPa-grade high-strength structure steel does not have, and meets the requirements for the ultra-high strength steel safety performance and low manufacturing cost in complex and severe environments in the construction machinery industry.
Description
800 MPA CONSTRUCTION MACHINERY MEDIUM-MANGANESE MEDIUM-THICKNESS STEEL AND MANUFACTURING METHOD THEREFOR
[00011 The present disclosure relates to the technical field of steel smelting, and specifically relates to an 800 MPa construction machinery medium-manganese medium-thickness steel and a manufacturing method therefor.
[0002] The 800 MPa construction machinery steel is mainly used in large-scale electric shovels, drilling rigs, buckets of bulldozers, crane booms and turntables, and structural parts of coal machines. In this high-strength steel grade for engineering machinery, high contents of Ni, Mo and other relatively precious metal elements are added, and the LF and RH vacuum treatment are adopted to reduce the contents of P, S and inclusions and purify the molten steel. Controlled rolling, controlled cooling, relaxation-controlled precipitation and micro-alloy precipitation strengthening are adopted to refine grain and improve the strength of the steel plate. The heavy steel plate is required to be quenched and tempered, leading to high cost in raw materials and processes. Particularly, the heavy steel plate has poor hardenability, poor microstructure uniformity in the thickness direction, poor low-temperature impact toughness at its core, and excessively high yield ratio (generally around 0.95). The excessively high yield ratio makes the deformation capacity of the steel plate reduced, and the safety of structural parts during use is unguaranteed. Therefore, while increasing the strength of the steel plate, it is necessary to reduce its yield ratio. Reasonable strength, toughness, and plasticity is prerequisite in the design of high-strength structural steels for engineering machinery.
[00031 In recent years, the medium-manganese steel has been a research hotspot in the field of iron and steel materials. Increasing the content of Mn in the steel and reducing the content of precious alloying elements such as Ni, Cr, and Mo in the steel are capable of greatly reducing the overall cost of the steel. The properties of the medium-manganese steel solve the problems of poor low-temperature impact toughness and excessively high yield ratio of the high-strength structural steel for engineering machinery, and meets the safety performance and manufacturing cost requirements of the high-strength steel for the engineering machinery in complex and harsh environment.
[00041 To solve the above-mentioned technical problems and overcome the shortcomings in the prior art, the present disclosure provides an 800 MPa construction machinery medium-manganese medium-thickness steel and a manufacturing method therefor. A steel plate manufactured has excellent comprehensive mechanical properties, and meets the safety performance and manufacturing cost requirements of the ultra-high-strength steel for engineering machinery in complex and harsh environment.
[0005] To solve the above-mentioned technical problems, the present disclosure provides the 800 MPa construction machinery medium-manganese medium-thickness steel, which is composed of the following chemical composition in mass percentage: C: 0.05%-0.08%, Mn: 4.8%-5.8%, Si: 0.10%-0.35%, P < 0.010%, S < 0.003%, Ti: 0.01%-0.05%, Ni + Cr + Mo: 0.7%-1.2%, and a balance of Fe and unavoidable impurities.
[00061 The technical effects are as follows: The present disclosure replaces the Ni-Cr-Mo alloy with Mn to be added in the steel plate to improve the hardenability. In this way, a martensite is obtained in a wide range of cooling rates, and then a small amount of reversed austenite is formed during tempering in the two-phase region. The tempered martensite improves the strength of the steel plate, and the reversed austenite improves the toughness and plasticity of the steel plate, so that the steel plate has high strength, low yield ratio, good microstructure uniformity along the thickness direction, and excellent mechanical properties at its core compared with the common 800 MPa high-strength structural steel, and meets the safety performance and manufacturing cost requirements of the ultra-high-strength steel for engineering machinery in complex and harsh environment.
[00071 The technical solutions further defined by the present disclosure are as follows:
[00081 A thickness of the steel plate manufactured by the 800 MPa medium-manganese medium-thick steel is 12-50 mm.
[00091 A yield ratio of the steel plate manufactured by the 800 MPa construction machinery medium-manganese medium-thickness steel is < 0.88.
[00101 The 800 MPa construction machinery medium-manganese medium-thickness steel described above is composed of the following chemical composition in mass percentage: C: 0.055%-0.080%, Mn: 4.85%-5.80%, Si: 0.11%-0.35%, P 0.009%, S < 0.002%, Ti: 0.015%-0.045%, Ni + Cr + Mo: 0.75%-1.20%, and the balance of Fe and inevitable impurities.
[0011] The 800 MPa construction machinery medium-manganese medium-thickness steel described above is composed of the following chemical composition in mass percentage: C: 0.055%-0.080%, Mn: 4.85%-5.80%, Si: 0.11%-0.35%, P < 0.009%, S < 0.002%, Ti:
0.015%-0.045%, Ni + Cr + Mo: 0.75%-1.20%, and the balance of Fe and inevitable impurities.
[00121 Another object of the present disclosure is providing the manufacturing method of the 800 MPa construction machinery medium-manganese medium-thickness steel. The manufacturing method comprises:
[00131 molten iron desulfurization treatment and converter smelting: contents of P and S in molten steel being 0.010% and 0.003%, respectively;
[00141 ladle furnace (LF) refining: meeting alloying requirements of a composition system;
[0015] continuous casting: a casting speed being < 1.5 m/min, and cleaning up surface defects of a slab obtained;
[0016] slab heating: heating the slab at 1080-1200 °C;
[00171 slab rolling: carrying out a two-stage rolling process, wherein, an initial rolling temperature and a final rolling temperature in a first stage are < 1030 °C and > 930 °C, respectively, and the initial rolling temperature and the final rolling temperature in a second stage are < 890 °C and > 800 °C, respectively;
[00181 post-rolling accelerated cooling control (ACC): a cooling rate being > 1 C/s, and a self-tempering temperature of a surface of the steel plate after cooling being < 200 °C; and
[00191 post-rolling heat treatment: tempering the steel plate at 600-650 °C, and then air-cooling the steel plate to room temperature after tempering.
[0020] The manufacturing method of the 800 MPa construction machinery medium-manganese medium-thickness steel is described above, in the slab heating, a soaking time is calculated by the thickness of the steel plate x (1.2-2.5 min/cm).
[00211 The manufacturing method of the 800 MPa construction machinery medium-manganese medium-thickness steel is described above, in the post-rolling heat treatment, the soaking times is calculated by the thickness of the steel plate x (1.5-3 min/cm).
[00221 The manufacturing method of the 800 MPa construction machinery medium-manganese medium-thickness steel is described above, in the post-rolling heat treatment, the steel plate with the thickness of less than 40 mm is fed into a heat treatment furnace for tempering within 72 hours after rolling, and the steel plate with the thickness of greater than 40 mm is fed into the heat treatment furnace for tempering within 48 hours after rolling.
[0023] The beneficial effects of the present disclosure are as follows:
[00241 (1) In the present disclosure, C is an important strengthening element capable of significantly improving the microstructure strength through interstitial solid solution strengthening and enhancing the stability of austenite. However, the addition amount of C is required to be controlled at a rational level to ensure low-temperature impact toughness and weldability of the steel plate.
[00251 Mn is capable of improving the microstructure strength through solid solution strengthening. An appropriate content of Mn is capable of significantly enhancing the stability of austenite. Increasing the content of Mn is capable of improving the hardenability of the steel plate, so that the steel plate forms martensite and even full martensite in a wide range of cooling rates, and then forms a small amount of reversed austenite during tempering in the two-phase region. The tempered martensite improves the strength of the steel plate, and the reversed austenite improves the toughness and plasticity of the steel plate, so that the steel plate has excellent comprehensive mechanical properties.
[0026] Si is a deoxidizing element in the steelmaking process. An appropriate content of Si added is capable of inhibiting the segregation of Mn and P and the formation of cementite, and improving the toughness of the steel plate. However, the excessively high content of Si would significantly reduce the toughness of the steel plate. Therefore, the content of Si in the present disclosure is controlled to be 0.10%-0.35%.
[00271 A certain content of Mn added in the present disclosure makes S easy to form MnS with Mn to reduce the plasticity of the steel plate. P is prone to segregate at the grain boundary to reduce the crack growth resistance of the grain boundary. Thus, the toughness of the steel plate is reduced. Therefore, the contents of P and S in the present disclosure are strictly controlled to be < 0.010% and 0.003%, respectively.
[00281 Ti is capable of hindering the grain boundary migration at high temperature through the precipitation of the fine and dispersed second phase, to refine the grains and improve the mechanical properties of the steel plate. The content of Ti in the present disclosure is controlled to be 0.01%- 0.05%.
[00291 An appropriate content of Cr added is capable of generating significant solid solution strengthening effect to improve the strength of the steel plate. An appropriate content of Ni added is capable of stabilizing the austenite phase, improving the hardenability, and reducing the ductile-brittle transition temperature to improve the weldability of the steel plate. Mo is capable of improving the strength of tempered martensite, and reducing the grain boundary segregation of Mn within a certain content range to improve the toughness of the steel plate. The content of Ni + Cr + Mo in the present disclosure is controlled to be within the range of 0.7%-1.2%, so that their effects are exerted without significantly increasing the cost.
[0030] (2) In the composition design of the present disclosure, Mn is the main alloying element, and no or less precious alloying elements are added. Thus, the cost per ton of steel is reduced compared to the traditional high-strength structural steel of the same level.
[0031] (3) The present disclosure adopts tempered martensite + a small amount of reversed austenite to form the microstructure of the steel plate. The tempered martensite ensures the strength of the steel plate, and a small amount of reversed austenite improves the plasticity and toughness of the steel plate under the condition of ensuring the strength. Due to the good hardenability, the tempered martensite + a small amount of reversed austenite are formed in the whole thickness direction.
[00321 (4) The thickness of the steel plate manufactured by the present disclosure is 12-50 mm, and the comprehensive mechanical properties of the steel plate meet the technical requirements of Q800F steel in GB/T16270-2009 high-strength structural steels. At the same time, the yield ratio of the steel plate is < 0.88.
[00331 FIG.1 is a schematic diagram of a metallographic structure of a steel plate at a 1/2
thickness in Example 1; and
[00341 FIG.2 is a schematic diagram of the metallographic structure of the steel plate at a 1/4
thickness in Example 1.
[00351 Example 1
[00361 This example provides the 800 MPa construction machinery medium-manganese medium-thickness steel with the thickness of 16 mm, composed of the following chemical composition in mass percentage: C: 0.06%, Mn: 5.1%, Si: 0.26%, P: 0.007%, S: 0.001%, Ti: 0.035%, Ni + Cr + Mo: 0.92%, and the balance of Fe and unavoidable impurities.
[0037] The manufacturing method is as follows: Converter smelting is carried out after the molten iron desulfurization treatment is performed, so that the contents of P and S in the molten steel are reduced to be 0.007% and 0.001%, respectively. The elements in the required mass fraction are alloyed after the ladle furnace (LF) refining is completed. The continuous casting is carried out with the casting speed of 1.2 m/min, to obtain the slab with the thickness of 320 mm. The surface defects of the slab are cleaned up. The obtained slab is heated to 1160 °C for 48 min. The heated slab is performed with the controlled rolling. The initial rolling temperature and the final rolling temperature in the first stage are 1030 °C and 945 °C, respectively. The initial rolling temperature and the final rolling temperature in the second stage are 882 °C and 811 °C, respectively. The rolled steel plate is water-cooled with the cooling rate of 5.1 °C/s, and the self-tempering temperature of the surface of the steel plate after cooling is lower than 200 °C.
The steel plate is fed into the heat treatment furnace within 48 h after rolling for tempering immediately at 630 °C for 35 min. The tempered steel plate is air-cooled to room temperature.
[0038] Example 2
[00391 This example provides the 800 MPa construction machinery medium-manganese medium-thickness steel with the thickness of 35 mm, composed of the following chemical composition in mass percentage: C: 0.065%, Mn: 5.3%, Si: 0.26%, P: 0.007%, S: 0.001%, Ti: 0.021%, Ni + Cr + Mo: 1.13%, and the balance of Fe and unavoidable impurities.
[0040] The manufacturing method is as follows: Converter smelting is carried out after the molten iron desulfurization treatment is performed, so that the contents of P and S in the molten steel are reduced to be 0.007% and 0.001%, respectively. The elements in the required mass fraction are alloyed after the LF refining is completed. The continuous casting is carried out with the casting speed of 1.2 m/min, to obtain the slab with the thickness of 320 mm. The surface defects of the slab are cleaned up. The obtained slab is heated to 1150 °C for 48 min. The heated slab is performed with the controlled rolling. The initial rolling temperature and the final rolling temperature in the first stage are 1030 °C and 940 °C, respectively. The initial rolling temperature and the final rolling temperature in the second stage are 865 °C and 825 °C, respectively. The rolled steel plate is water-cooled with the cooling rate of 6.3 °C/s, and the self-tempering temperature of the surface of the steel plate after cooling is lower than 200 °C. Tempering is carried out immediately after rolling at 630 °C for 77 min. The tempered steel plate is air-cooled to room temperature.
[0041] Example 3
[00421 This example provides the 800 MPa construction machinery medium-manganese medium-thickness steel with the thickness of 50 mm, composed of the following chemical composition in mass percentage: C: 0.075%, Mn: 5.5%, Si: 0.23%, P: 0.007%, S: 0.001%, Ti: 0.021%, Ni + Cr + Mo: 1.15%, and the balance of Fe and unavoidable impurities.
[00431 The manufacturing method is as follows: Converter smelting is carried out after the molten iron desulfurization treatment is performed, so that the contents of P and S in the molten steel are reduced to be 0.007% and 0.001%, respectively. The elements in the required mass fraction are alloyed after the LF refining is completed. The continuous casting is carried out with the casting speed of 1.2 m/min, to obtain the slab with the thickness of 320 mm. The surface defects of the slab are cleaned up. The obtained slab is heated to 1125 °C for 55 min. The heated slab is performed with the controlled rolling. The initial rolling temperature and the final rolling temperature in the first stage are 1025 °C and 945 °C, respectively. The initial rolling temperature and the final rolling temperature in the second stage are 870 °C and 845 °C, respectively. The rolled steel plate is water-cooled with the cooling rate of 10.3 °C/s, and the self-tempering temperature of the surface of the steel plate after cooling is lower than 200 °C. The steel plate is fed into the heat treatment furnace within 72 h after rolling for tempering immediately at 620 °C for 110 min. The tempered steel plate is air-cooled to room temperature.
[00441 The comprehensive mechanical properties test of the steel plates manufactured in Examples 1-3 is carried out, and the results are shown in the following table.
[00451 Examples Thickn Samplin Proerties result ess/m g site Yield Tensile Yield Elonga Bend Charpy impact m strength/ strength/ ratio tion/% test energy/J MPa MPa d =2a -60 °C Example 1 intact 242 1/4t 855 986 0.867 24 269 253 16 intact 231 1/2t 845 977 0.865 23 252 246 Example 2 intact 221 1/4t 841 968 0.869 24 248 232 35 intact 215 1/2t 832 954 0.872 23 231 243 Example 3 intact 198 1/4t 815 943 0.864 26 205 174 50 intact 185 1/2t 807 936 0.862 25 143 152
[0046] It can be seen from FIGs. 1 and 2 that the microstructure of the steel plate in Example 1 is formed by the tempered martensite + a small amount of reversed austenite. The tempered martensite + a small amount of reversed austenite are formed in the whole thickness direction. The tempered martensite ensures the strength of the steel plate, and a small amount of reversed austenite improves the plasticity and toughness of the steel plate under the condition of ensuring the strength. It can be seen from the above-mentioned table that the comprehensive mechanical properties of the steel plate manufactured by the present disclosure meet the technical requirements of Q800F steel in GB/T16270-2009 high-strength structural steels, and the yield ratio of the steel plate is < 0.88. In the composition design of the present disclosure, Mn is the main alloying element, and no or less precious alloying elements are added. Thus, the cost per ton of steel is reduced compared to the traditional high-strength structural steel of the same level.
The steel plate of the present disclosure has a broad application prospect due to its excellent comprehensive mechanical properties and reduced cost.
[0047] In addition to the above-mentioned examples, the present disclosure may also have other examples. All technical solutions formed by equivalent replacements or transformations shall fall within the protection scope of the present disclosure.
Claims (9)
1. An 800 MPa construction machinery medium-manganese medium-thickness steel, wherein, the 800 MPa construction machinery medium-manganese medium-thickness steel is composed of the following chemical composition in mass percentage: C: 0.05%-0.08%, Mn: 4.8%-5.8%, Si: 0.10%-0.35%, P 0.010%, S < 0.003%, Ti: 0.01%-0.05%, Ni + Cr + Mo: 0.7%-1.2%, and a balance of Fe and unavoidable impurities.
2. The 800 MPa construction machinery medium-manganese medium-thickness steel according to claim 1, wherein, a thickness of a steel plate obtained is 12-50 mm.
3. The 800 MPa construction machinery medium-manganese medium-thickness steel according to claim 1, wherein, a yield ratio of the steel plate is < 0.88.
4. The 800 MPa construction machinery medium-manganese medium-thickness steel according to claim 1, wherein, the 800 MPa construction machinery medium-manganese medium-thickness steel is composed of the following chemical composition in mass percentage: C: 0.055%-0.080%, Mn: 4.85%-5.80%, Si: 0.11%-0.35%, P 0.009%, S 0.002%, Ti: 0.015%-0.045%, Ni + Cr + Mo: 0.75%-1.20%, and the balance of Fe and inevitable impurities.
5. The 800 MPa construction machinery medium-manganese medium-thickness steel according to claim 1, wherein, the 800 MPa construction machinery medium-manganese medium-thickness steel is composed of the following chemical composition in mass percentage: C: 0.055%-0.080%, Mn: 4.85%-5.80%, Si: 0.11%-0.35%, P 0.009%, S 0.002%, Ti: 0.015%-0.045%, Ni + Cr + Mo: 0.75%-1.20%, and the balance of Fe and inevitable impurities.
6. A manufacturing method of the 800 MPa construction machinery medium-manganese medium-thickness steel as described in any one of claims 1-5, wherein, comprising
molten iron desulfurization treatment and converter smelting: contents of P and S in molten steel being < 0.010% and < 0.003%, respectively; ladle furnace (LF) refining: meeting alloying requirements of a composition system; continuous casting: a casting speed being < 1.5 m/min, and cleaning up surface defects of a slab obtained; slab heating: heating the slab at 1080-1200 °C; slab rolling: carrying out a two-stage rolling process, wherein, an initial rolling temperature and a final rolling temperature in a first stage are < 1030 °C and > 930 °C, respectively, and the initial rolling temperature and the final rolling temperature in a second stage are < 890 °C and >
800 °C, respectively; post-rolling accelerated cooling control (ACC): a cooling rate being > 1 °C/s, and a self-tempering temperature of a surface of the steel plate after cooling being < 200 °C; and post-rolling heat treatment: tempering the steel plate at 600-650 °C, and then air-cooling the steel plate to room temperature after tempering.
7. The manufacturing method of the 800 MPa construction machinery medium-manganese medium-thickness steel according to claim 6, wherein, in the slab heating, a soaking time is calculated by the thickness of the steel plate x (1.2-2.5 min/cm).
8. The manufacturing method of the 800 MPa construction machinery medium-manganese medium-thickness steel according to claim 6, wherein, in the post-rolling heat treatment, the soaking times is calculated by the thickness of the steel plate x (1.5-3 min/cm).
9. The manufacturing method of the 800 MPa construction machinery medium-manganese medium-thickness steel according to claim 6, wherein, in the post-rolling heat treatment, the steel plate with the thickness of less than 40 mm is fed into a heat treatment furnace for tempering within 72 hours after rolling, and the steel plate with the thickness of greater than 40 mm is fed into the heat treatment furnace for tempering within 48 hours after rolling.
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| CN202010584497.1 | 2020-06-24 | ||
| CN202010584497.1A CN111778450A (en) | 2020-06-24 | 2020-06-24 | Medium-manganese medium-thickness steel for 800MPa engineering machinery and manufacturing method thereof |
| PCT/CN2020/122967 WO2021258584A1 (en) | 2020-06-24 | 2020-10-22 | 800 mpa construction machinery medium-manganese medium-thickness steel and manufacturing method therefor |
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| AU2020455074A1 true AU2020455074A1 (en) | 2023-02-02 |
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| CN104630641B (en) * | 2014-12-11 | 2017-02-22 | 武汉钢铁(集团)公司 | 800MPa-grade high-strength high-plasticity low-carbon medium-manganese steel and manufacturing method thereof |
| US11519050B2 (en) * | 2016-09-16 | 2022-12-06 | Salzgitter Flachstahl Gmbh | Method for producing a re-shaped component from a manganese-containing flat steel product and such a component |
| KR102030815B1 (en) * | 2016-12-28 | 2019-10-11 | 연세대학교 산학협력단 | High intensity medium manganese steel forming parts for warm stamping and manufacturing method for the same |
| CN108660395B (en) * | 2018-05-30 | 2019-12-06 | 东北大学 | 690 MPa-grade low-carbon medium-manganese high-strength medium plate |
| EP3594368A1 (en) * | 2018-07-13 | 2020-01-15 | voestalpine Stahl GmbH | Medium manganese steel intermediate product with reduced carbon content and method for providing such a steel intermediate product |
| CN109652733B (en) * | 2019-01-07 | 2021-01-26 | 南京钢铁股份有限公司 | 690 MPa-grade super-thick steel plate and manufacturing method thereof |
| CN110714173A (en) * | 2019-07-25 | 2020-01-21 | 东莞材料基因高等理工研究院 | Low-carbon medium manganese steel medium plate containing epsilon martensite and preparation method thereof |
| CN110846577A (en) * | 2019-11-20 | 2020-02-28 | 南京钢铁股份有限公司 | 690 MPa-grade high-strength low-yield-ratio medium-thickness manganese steel and manufacturing method thereof |
| CN110983158B (en) * | 2019-12-16 | 2021-04-20 | 南京钢铁股份有限公司 | 550 MPa-grade medium manganese steel plate and manufacturing method thereof |
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