CN108467991B - High-strength and high-toughness high manganese steel for ultralow temperature and heat treatment process thereof - Google Patents
High-strength and high-toughness high manganese steel for ultralow temperature and heat treatment process thereof Download PDFInfo
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Abstract
The invention provides a high-strength and high-toughness high manganese steel for ultralow temperature, which consists of the following elements in percentage by mass: c: 0.3 to 0.6 percent; si: 0.02-0.1%; mn: 20.0 to 26.0 percent; al: 0.5-2.5%; nb: 0.05 to 0.3 percent; p: less than or equal to 0.010 percent; s: less than or equal to 0.002 percent; n: 0.004-0.010%; o: 0.0005-0.002%; the balance being Fe. The invention further provides a heat treatment process for the ultra-low temperature high-strength high-toughness high manganese steel. The high-strength and high-toughness high manganese steel for the ultra-low temperature and the heat treatment process thereof provided by the invention are prepared by the heat treatment process of cold rolling, low-temperature aging and high-temperature recrystallization, have good strength and excellent plasticity, have good weldability, are low in cost and are simple and easy in heat treatment process.
Description
Technical Field
The invention belongs to the technical field of low-temperature steel, and relates to high-strength high-toughness high-manganese steel used at ultralow temperature and a heat treatment process thereof.
Background
With the rapid development of equipment manufacturing such as global marine drilling platforms, submarine oil and gas transportation, oil and gas storage and transportation and the like, the demand of high-strength high-toughness low-temperature steel, particularly low-temperature marine steel used in marine environments, is remarkably increased. At present, the steel materials widely applied to ultralow temperature mainly comprise Ni-rich ferrite type low-temperature steel and austenite type low-temperature steel. Taking the steel for the ocean platform as an example, the high-strength tough steel in the self-elevating drilling platform accounts for 55-60%, and the semi-submersible drilling platform accounts for 90-98%, wherein the pile legs, the cantilever beams, the upgrading rack mechanism and the like for the platform are required to ensure the strength grade (460 plus 690MPa) and simultaneously give consideration to excellent low-temperature impact toughness (-80 ℃ impact energy > 100J).
Although the Ni-based ferritic low-temperature steel and the austenitic stainless steel have good properties, they are expensive, and the Ni element greatly affects the low-temperature toughness of the low-temperature steel, and the higher the content is, the greater the effect is. Therefore, high manganese austenitic low temperature steels are gradually developing into the most practical and economical low temperature structural materials, and although Mn is very effective for lowering the ductile-brittle transition temperature, by increasing the Mn/C ratio in low temperature steels, the toughness of the steels can be significantly improved. However, the yield limit of the single-phase austenite type low-temperature steel is low, the ideal strength level cannot be achieved, and the comprehensive strength and toughness are poor. Therefore, further research and investigation on the strengthening and toughening of high manganese low temperature steel are necessary.
In order to ensure that the high manganese series low temperature steel has excellent strength, a plurality of strengthening mechanisms, such as fine grain strengthening and precipitation strengthening, need to be introduced; in order to make precipitation strengthening not to destroy the plasticity of low-temperature steel, the size of precipitated phase needs to be in nanometer level, and various types of nano carbide particles such as kappa carbide and MC carbide can be formed by adding Al, Nb and the like. Meanwhile, on the basis of grain refinement, the austenite still can generate twin induced plasticity (TWIP) effect under low-temperature deformation, and the Stacking Fault Energy (SFE) and the deformation mechanism can be controlled by generally controlling the element content and the grain size in the austenite. If the Mn content is too high, the austenite fault energy is very high, the low-temperature deformation mechanism is dislocation slip, and twin crystals cannot be generated; when the content of Mn is low, martensite transformation easily occurs at austenite low temperature, and cracks are easily induced at the interface, so that the stacking fault energy needs to be strictly controlled. Meanwhile, the grain refinement can obviously inhibit the generation of twin crystals and improve the stability. Therefore, the alloy composition design of the high manganese series low-temperature steel is carried out according to the structural requirements, and a novel heat treatment process is provided to prepare the high manganese series ultralow-temperature steel with high strength and toughness.
Disclosure of Invention
In view of the above-mentioned disadvantages of the prior art, the present invention aims to provide a high-strength and high-toughness high-manganese steel for ultra-low temperature and a heat treatment process thereof, which can obtain a composite structure of austenite and nano precipitated phase with effective grain refinement and twinning distribution by using low-temperature aging and high-temperature recrystallization treatments, solve the problems of low strength and poor overall strength and toughness of the existing manganese-based low-temperature steel, and can manufacture structural steel for use in ultra-low temperature environments.
In order to achieve the above objects and other related objects, a first aspect of the present invention provides a high-strength high-manganese steel for ultra-low temperature, which comprises the following elements by mass:
c (carbon): 0.3 to 0.6 percent; si (silicon): 0.02-0.1%; mn (manganese): 20.0 to 26.0 percent; al (aluminum): 0.5-2.5%; nb (niobium): 0.05 to 0.3 percent; p (phosphorus): less than or equal to 0.010 percent; s (sulfur): less than or equal to 0.002 percent; n (nitrogen): 0.004-0.010%; o (oxygen): 0.0005-0.002%; the balance being Fe (iron).
Preferably, the high-strength high-manganese steel for ultralow temperature has optional element composition selected from one of the following:
1) the high-strength high-toughness high-manganese steel for the ultra-low temperature comprises the following elements in percentage by mass:
c: 0.3-0.4%; si: 0.02-0.05%; mn: 25.0 to 26.0 percent; al: 1.5 to 2.5 percent; nb: 0.06-0.3%; p: less than or equal to 0.010 percent; s: less than or equal to 0.002 percent; n: 0.004-0.010%; o: 0.0005-0.002%; the balance being Fe.
2) The high-strength high-toughness high-manganese steel for the ultra-low temperature comprises the following elements in percentage by mass:
c: 0.4-0.5%; si: 0.02-0.1%; mn: 23.0 to 25.0 percent; al: 0.5-2.5%; nb: 0.06-0.25%; p: less than or equal to 0.010 percent; s: less than or equal to 0.002 percent; n: 0.004-0.010%; o: 0.0005-0.002%; the balance being Fe.
3) The high-strength high-toughness high-manganese steel for the ultra-low temperature comprises the following elements in percentage by mass:
c: 0.4-0.6%; si: 0.05 to 0.1 percent; mn: 22.5 to 24.0 percent; al: 0.5-1.5%; nb: 0.06-0.25%; p: less than or equal to 0.010 percent; s: less than or equal to 0.002 percent; n: 0.004-0.010%; o: 0.0005-0.002%; the balance being Fe.
More preferably, the high-strength high-manganese steel for ultralow temperature use consists of the following elements in percentage by mass:
c: 0.4-0.5%; si: 0.02-0.05%; mn: 23.5 to 24.5 percent; al: 1.5 to 2.5 percent; nb: 0.06-0.15%; p: less than or equal to 0.010 percent; s: less than or equal to 0.002 percent; n: 0.004-0.010%; o: 0.0005-0.002%; the balance being Fe.
The high-strength and high-toughness high-manganese steel disclosed by the invention is composed of elements, wherein carbon can be used for obviously improving the strength of low-temperature steel and improving the stability of austenite and is an effective carbide forming element. The manganese element can effectively reduce the toughness-brittleness transition temperature, and the toughness of the steel can be obviously improved by improving the Mn/C ratio in the low-temperature steel. In addition, a proper amount of elements such as aluminum and the like are added into the low-temperature steel, so that the stacking fault energy of austenite can be effectively improved, nano particles similar to kappa carbide can be formed, and meanwhile, niobium-rich MC carbide can be formed by adding trace Nb, so that the strength can be greatly improved, and the low-temperature toughness of the low-temperature steel can be ensured. Meanwhile, for manganese series low-temperature steel, the most important thing in the smelting process is to control the content of S, P, N, O and other impurity elements and inhibit the formation of inclusions such as MnS, which is an important means for improving the low-temperature toughness of the low-temperature steel.
The second aspect of the invention provides a heat treatment process for ultralow-temperature high-strength high-toughness high-manganese steel, which comprises the following steps:
A) mixing the element components according to the proportion, casting the mixture into a steel ingot, heating the steel ingot at 1150-minus 1250 ℃ and preserving the heat for more than or equal to 2 hours, then carrying out multi-step hot rolling from the initial rolling temperature of 1045-minus 1055 ℃ to the final rolling temperature of 745-minus 755 ℃, and then carrying out air cooling;
B) and (3) carrying out heat treatment on the steel ingot after air cooling, firstly carrying out cold rolling treatment to obtain a cold-rolled sheet, carrying out low-temperature aging precipitation on the cold-rolled sheet at the temperature range of 450-550 ℃, then carrying out water quenching to room temperature, finally carrying out high-temperature recrystallization, and then carrying out water quenching again to room temperature to obtain the high-strength and high-toughness high-manganese steel at the ultralow temperature.
Preferably, in step a), the temperature of the heating is 1200 ℃.
Preferably, in the step A), the initial rolling temperature is 1050 ℃, and the final rolling temperature is 750 ℃.
Preferably, in step a), the multi-step hot rolling comprises the steps of:
the first step is as follows: hot rolling temperature: 1045 and 1055 ℃, and the heat preservation time: 165-175 minutes;
the second step is that: hot rolling temperature: 975-: 115 ℃ for 125 minutes;
the third step: hot rolling temperature: 845 ℃, 855 ℃ and the heat preservation time: 85-95 minutes;
the fourth step: hot rolling temperature: 825 and 835 ℃, and the heat preservation time: 65-75 minutes;
the fifth step: hot rolling temperature: 805-815 ℃, and the heat preservation time: 45-55 minutes;
and a sixth step: hot rolling temperature: 775 + 785 ℃, heat preservation time: 35-45 minutes;
the seventh step: hot rolling temperature: 765 775 ℃, heat preservation time: 27-37 minutes;
eighth step: the finishing temperature is as follows: 745 ℃ and 755 ℃, and the heat preservation time: 20-30 minutes.
More preferably, the multi-step hot rolling comprises the steps of:
the first step is as follows: hot rolling temperature: 1050 ℃, heat preservation time: 170 minutes;
the second step is that: hot rolling temperature: 980 ℃, heat preservation time: 120 minutes;
the third step: hot rolling temperature: and (3) keeping the temperature at 850 ℃ for a period of time: 90 minutes;
the fourth step: hot rolling temperature: 830 ℃, heat preservation time: 70 minutes;
the fifth step: hot rolling temperature: 810 ℃, heat preservation time: 50 minutes;
and a sixth step: hot rolling temperature: 780 ℃, heat preservation time: 40 minutes;
the seventh step: hot rolling temperature: 770 ℃, holding time: 32 minutes;
eighth step: the finishing temperature is as follows: 750 ℃, heat preservation time: for 25 minutes.
Preferably, in the step a), each reduction of the multi-step hot rolling is maintained at 20 to 30%.
The reduction rate is a reduction rate at which rolling and forging often indicate a degree of deformation with respect to a relative deformation. When the rolling reduction rate of the multiple steps is kept in a stable range as much as possible, the rolling effect is better.
Preferably, in the step B), the heat treatment process comprises cold rolling treatment, low-temperature aging and high-temperature recrystallization.
Preferably, in step B), the cold rolling process is a single rolling at room temperature.
More preferably, the reduction ratio of the cold rolling treatment is 60 to 75%.
Preferably, in the step B), the temperature range of the low-temperature aging is 480-530 ℃, and the precipitation time of the low-temperature aging is 3-4 h. More preferably, the temperature of the low-temperature aging is 500 ℃, and the precipitation time of the low-temperature aging is 3 h.
Preferably, in the step B), the temperature range of the high-temperature recrystallization is 750-850 ℃, and the holding time of the high-temperature recrystallization is 60-90 s.
More preferably, the temperature range of the high-temperature recrystallization is 780-830 ℃, and the holding time of the high-temperature recrystallization is 70-90 s.
Further preferably, the temperature range of the high-temperature recrystallization is 800 ℃, and the holding time of the high-temperature recrystallization is 90 s.
Preferably, in the step B), the water quenching is to cool the product after low-temperature aging or high-temperature recrystallization to room temperature by water.
The room temperature is 20-25 ℃.
As described above, the high-strength and high-toughness high-manganese steel for ultra-low temperature and the heat treatment process thereof provided by the invention have the advantages that through the cold rolling, low-temperature aging and high-temperature recrystallization processes, proper aging temperature and time are selected, effective nanophase dispersion precipitation is realized in the matrix in the first step, the precipitation of carbide can be promoted due to the very high dislocation density of the matrix, the composite structure of austenite and precipitated phase with size gradient distribution is obtained through the pinning effect of the nanophase dispersed phase in the second step of recrystallization, and through the comprehensive influence of the nanophase dispersed phase and the bicrystallized austenite, the TWIP effect of the austenite is utilized in the low-temperature stretching process, fine grain strengthening and precipitation strengthening of the nanophase dispersed phase are realized, so that the high-strength high-manganese steel has good strength and excellent plasticity, and has good weldability, low cost and simple heat treatment process.
The invention provides a high-strength and high-toughness high manganese steel for ultralow temperature and a heat treatment process thereof, which solve the problems of lower strength and poorer overall strength and toughness of the existing manganese low-temperature steel, namely, a composite structure of austenite and a nano precipitated phase with effective grain refinement and twinned distribution is obtained by utilizing low-temperature aging and high-temperature recrystallization treatment, the strength and toughness of the manganese low-temperature steel are effectively improved, the high-strength and high-toughness high manganese steel can be used for manufacturing structural steel used in an ultralow temperature environment, and the structural steel can obtain a structural steel with the yield strength of 900-plus-1100 MPa, the tensile strength of 1400-plus-1600 MPa, the elongation of 50-60 percent and the impact toughness of 100-plus-130J/cm at the temperature of-196 DEG2The high-strength and high-toughness high manganese steel.
Drawings
FIG. 1 shows the SEM microstructures of high-strength low-temperature resistant steel of example 1 of the present invention, FIGS. 1a and 1b, wherein 1a is the SEM microstructure before heat treatment; and 1b is a scanning electron microscopic microstructure picture after heat treatment.
FIG. 2 shows the SEM micrographs of high-strength low-temperature resistant steel of example 2 of the present invention, namely, 2a and 2b, wherein 2a is the SEM micrographs before heat treatment; and 2b is a scanning electron microscopic microstructure picture after heat treatment.
FIG. 3 is a graph showing the impact properties of the high-strength low-temperature-resistant steel of examples 1 to 2 of the present invention at-196 ℃ before and after heat treatment.
Detailed Description
The present invention is further illustrated below with reference to specific examples, which are intended to be illustrative only and not to limit the scope of the invention.
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
It should be understood that the processing equipment or devices not specifically mentioned in the following examples are conventional in the art; all pressure values and ranges refer to relative pressures.
Furthermore, it is to be understood that one or more method steps mentioned in the present invention does not exclude that other method steps may also be present before or after the combined steps or that other method steps may also be inserted between these explicitly mentioned steps, unless otherwise indicated; it is also to be understood that a combined connection between one or more devices/apparatus as referred to in the present application does not exclude that further devices/apparatus may be present before or after the combined device/apparatus or that further devices/apparatus may be interposed between two devices/apparatus explicitly referred to, unless otherwise indicated. Moreover, unless otherwise indicated, the numbering of the various method steps is merely a convenient tool for identifying the various method steps, and is not intended to limit the order in which the method steps are arranged or the scope of the invention in which the invention may be practiced, and changes or modifications in the relative relationship may be made without substantially changing the technical content.
The raw materials containing elements such as carbon, silicon, manganese, aluminum, niobium, phosphorus, sulfur, nitrogen, oxygen, and iron used in the following examples are commercially available, and equipment for carrying out processes such as hot rolling, cold rolling, low-temperature aging, high-temperature recrystallization, and water quenching is also commercially available.
Example 1
Taking raw materials containing various element components according to the proportion, mixing the raw materials, and casting the mixture into a steel ingot, wherein the components comprise the following elements in percentage by mass: c: 0.4-0.5%; si: 0.02-0.1%; mn: 23.0 to 25.0 percent; al: 0.5-2.5%; nb: 0.06-0.25%; p: less than or equal to 0.010 percent; s: less than or equal to 0.002 percent; n: 0.004-0.010%; o: 0.0005-0.002%; the balance being Fe. Heating the steel ingot at 1200 ℃, preserving heat for 2 hours, then carrying out multi-step hot rolling from the initial rolling temperature of 1050 ℃ to the final rolling temperature of 750 ℃, and then air-cooling, wherein the thickness of the steel ingot is 240 mm. Wherein, the multi-step hot rolling conditions are as follows: the reduction ratios are respectively 29.17%, 29.41%, 25%, 22.22%, 21.43%, 20% and 21.88% under 1050, 980, 850, 830, 810, 780, 770 and 750 ℃ and the holding time is respectively 170, 120, 90, 70, 50, 40, 32 and 25 minutes. The high manganese steel hot-rolled steel plate is derusted and deoiled and cleaned, so that the phenomenon of uneven stress in the heat treatment process is avoided. The hot rolled ingot is examined under a scanning electron microscope, and a specific microstructure picture is shown in figure 1 a.
Then, cold rolling and heating the hot-rolled low-temperature steel, namely, the cold rolling reduction is 70%, then, low-temperature aging is carried out, namely, isothermal aging precipitation is carried out for 3 hours within the temperature range of 500 ℃, and then, water quenching is carried out to room temperature; and (3) recrystallizing the high manganese steel subjected to low-temperature aging treatment at 800 ℃ for 90s, and finally performing water quenching to room temperature. The obtained sample 1# of the low-temperature-resistant high-strength high-toughness high-manganese steel is detected under a scanning electron microscope, and a specific microstructure picture is shown in figure 1 b.
Example 2
Taking raw materials containing various element components according to the proportion, mixing the raw materials, and casting the mixture into a steel ingot, wherein the components comprise the following elements in percentage by mass: c: 0.4-0.6%; si: 0.05 to 0.1 percent; mn: 22.5 to 24.0 percent; al: 0.5-1.5%; nb: 0.06-0.25%; p: less than or equal to 0.010 percent; s: less than or equal to 0.002 percent; n: 0.004-0.010%; o: 0.0005-0.002%; the balance being Fe. Heating the steel ingot at 1200 ℃, preserving heat for 2 hours, carrying out multi-step hot rolling from the initial rolling temperature of 1050 ℃ to the final rolling temperature of 750 ℃, and then air-cooling, wherein the thickness of the steel ingot is 240 mm. Wherein, the multi-step hot rolling conditions are as follows: the reduction ratios are respectively 29.17%, 29.41%, 25%, 22.22%, 21.43%, 20% and 21.88% under 1050, 980, 850, 830, 810, 780, 770 and 750 ℃ and the holding time is respectively 170, 120, 90, 70, 50, 40, 32 and 25 minutes. The high manganese steel hot-rolled steel plate is derusted and deoiled and cleaned, so that the phenomenon of uneven stress in the heat treatment process is avoided. The hot rolled ingot is examined under a scanning electron microscope, and a specific microstructure picture is shown in figure 2 a.
Then, cold rolling and heating the hot-rolled low-temperature steel, namely, the cold rolling reduction is 70%, then, low-temperature aging is carried out, namely, isothermal aging precipitation is carried out for 3 hours within the temperature range of 500 ℃, and then, water quenching is carried out to room temperature; and (3) recrystallizing the high manganese steel subjected to low-temperature aging treatment at 800 ℃ for 90s, and finally performing water quenching to room temperature. The obtained sample 2# of the low-temperature-resistant high-strength high-toughness high-manganese steel is detected under a scanning electron microscope, and a specific microstructure picture is shown in figure 2 b.
Example 3
The results of observing austenite and precipitated phase of the low temperature resistant high-strength high-toughness high-manganese steel samples 1-2# in examples 1-2 by using a scanning electron microscope are shown in figures 1a, 1b, 2a and 2 b.
As is clear from FIGS. 1a, 1b, 2a and 2b, the hot rolled sample structure had coarse crystal grains of substantially about 12 μm, and a large number of annealed twin boundaries were present. After the subsequent treatment, the crystal grains are obviously thinned and distributed in a double crystal mode, namely, the crystal grains with different sizes are all distributed in a size range of 0.4-5 mu m. Meanwhile, a large amount of non-uniform nano precipitated phases are distributed in the matrix, the size is about 5-20nm, and basically, the structural deformation caused by cold rolling is eliminated by recrystallization after heat treatment. The size of the austenite with the twinned distribution benefits from the fact that the precipitated phase generated in the low-temperature aging process can pin the austenite grain boundary in the recrystallization process and inhibit the growth process of the austenite, and the uneven precipitated phase distribution also causes recrystallization in different degrees.
Example 4
The low-temperature tensile tests were carried out on the samples 1 to 2# of the low-temperature-resistant high-toughness high-manganese steel obtained in examples 1 to 2, and the specific results are shown in Table 1. As can be seen from Table 1, after heat treatment, the yield strength and tensile strength of the high manganese steel are significantly improved to the levels of 900-.
TABLE 1 comparison table of tensile mechanical properties at-196 ℃ before and after heat treatment of low temperature resistant high strength and toughness high manganese steel
Example 5
The low-temperature-resistant high-strength high-toughness high-manganese steel sample products 1-2# in the examples 1-2 are subjected to a low-temperature-196 ℃ impact test respectively, and the specific results are shown in the figure 3 and the table 1. As shown in FIG. 3 and Table 1, the impact toughness of the high-strength high-manganese steel is reduced to a certain extent at the liquid nitrogen temperature after the heat treatment, but the impact toughness is still higher than 100J/cm2. While maintaining high strength, good low temperature toughness is still achieved, which exceeds the standard value of impact toughness of high manganese steel in ASTM standard of 42.5J/cm2Thus obtaining the high-strength high-toughness high-manganese steel used at ultra-low temperature.
In conclusion, the high-strength and high-toughness high manganese steel for the ultra-low temperature and the heat treatment process thereof provided by the invention are prepared through the processes of cold rolling, low-temperature aging and high-temperature recrystallization, and have the advantages of good strength, excellent plasticity, good weldability, low cost and simple heat treatment process. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (10)
1. The high-strength high-toughness high-manganese steel for the ultra-low temperature comprises the following elements in percentage by mass:
c: 0.3 to 0.6 percent; si: 0.02-0.1%; mn: 20.0 to 26.0 percent; al: 0.5-2.5%; nb: 0.05 to 0.3 percent; p: less than or equal to 0.010 percent; s: less than or equal to 0.002 percent; n: 0.004-0.010%; o: 0.0005-0.002%; the balance being Fe;
the steel structure takes austenite with twinned distribution as a matrix and nano-scale carbide as a precipitated phase.
2. The high strength high manganese steel for ultra low temperature use according to claim 1, characterized by the elemental composition optionally selected from one of the following:
1) the high-strength high-toughness high-manganese steel for the ultra-low temperature comprises the following elements in percentage by mass:
c: 0.3-0.4%; si: 0.02-0.05%; mn: 25.0 to 26.0 percent; al: 1.5 to 2.5 percent; nb: 0.06-0.3%; p: less than or equal to 0.010 percent; s: less than or equal to 0.002 percent; n: 0.004-0.010%; o: 0.0005-0.002%; the balance being Fe;
2) the high-strength high-toughness high-manganese steel for the ultra-low temperature comprises the following elements in percentage by mass:
c: 0.4-0.5%; si: 0.02-0.1%; mn: 23.0 to 25.0 percent; al: 0.5-2.5%; nb: 0.06-0.25%; p: less than or equal to 0.010 percent; s: less than or equal to 0.002 percent; n: 0.004-0.010%; o: 0.0005-0.002%; the balance being Fe;
3) the high-strength high-toughness high-manganese steel for the ultra-low temperature comprises the following elements in percentage by mass:
c: 0.4-0.6%; si: 0.05 to 0.1 percent; mn: 22.5 to 24.0 percent; al: 0.5-1.5%; nb: 0.06-0.25%; p: less than or equal to 0.010 percent; s: less than or equal to 0.002 percent; n: 0.004-0.010%; o: 0.0005-0.002%; the balance being Fe.
3. The heat treatment process for ultra-low temperature high-toughness high-manganese steel according to any one of claims 1-2, comprising the steps of:
A) mixing the element components according to the proportion, casting the mixture into a steel ingot, heating the steel ingot at 1150-minus 1250 ℃ and preserving the heat for more than or equal to 2 hours, then carrying out multi-step hot rolling from the initial rolling temperature of 1045-minus 1055 ℃ to the final rolling temperature of 745-minus 755 ℃, and then carrying out air cooling;
B) and (3) carrying out heat treatment on the steel ingot after air cooling, firstly carrying out cold rolling treatment to obtain a cold-rolled sheet, carrying out low-temperature aging precipitation on the cold-rolled sheet at the temperature range of 450-550 ℃, then carrying out water quenching to room temperature, finally carrying out high-temperature recrystallization, and then carrying out water quenching again to room temperature to obtain the ultralow-temperature high-strength high-toughness high-manganese steel.
4. The heat treatment process for the ultra-low temperature high-toughness high-manganese steel according to claim 3, characterized in that the heating temperature in step A) is 1200 ℃.
5. The heat treatment process for the ultra-low temperature high-strength high-manganese steel according to claim 3, characterized in that in step A), the initial rolling temperature is 1050 ℃ and the final rolling temperature is 750 ℃.
6. The heat treatment process for ultra-low temperature high-toughness high-manganese steel according to claim 3, wherein in step A), the multi-step hot rolling comprises the following steps:
the first step is as follows: hot rolling temperature: 1045 and 1055 ℃, and the heat preservation time: 165-175 minutes;
the second step is that: hot rolling temperature: 975-: 115 ℃ for 125 minutes;
the third step: hot rolling temperature: 845 ℃, 855 ℃ and the heat preservation time: 85-95 minutes;
the fourth step: hot rolling temperature: 825 and 835 ℃, and the heat preservation time: 65-75 minutes;
the fifth step: hot rolling temperature: 805-815 ℃, and the heat preservation time: 45-55 minutes;
and a sixth step: hot rolling temperature: 775 + 785 ℃, heat preservation time: 35-45 minutes;
the seventh step: hot rolling temperature: 765 775 ℃, heat preservation time: 27-37 minutes;
eighth step: the finishing temperature is as follows: 745 ℃ and 755 ℃, and the heat preservation time: 20-30 minutes.
7. The heat treatment process for the ultra-low temperature high-strength high-manganese steel according to claim 3, characterized in that in step B), the cold rolling treatment is performed in a single step at room temperature; the reduction rate of the cold rolling treatment is 60-75%.
8. The heat treatment process for the ultra-low temperature high-strength high-toughness high-manganese steel as claimed in claim 3, wherein in the step B), the temperature range of the low-temperature aging is 480-530 ℃, and the precipitation time of the low-temperature aging is 3-4 h.
9. The heat treatment process for the ultra-low temperature high-strength high-manganese steel as claimed in claim 3, wherein in the step B), the temperature range of the high temperature recrystallization is 750-850 ℃, and the holding time of the high temperature recrystallization is 60-90 s.
10. The heat treatment process for the ultra-low temperature high-strength high-toughness high-manganese steel according to claim 3, wherein in the step B), the water quenching is to cool the product after low-temperature aging or high-temperature recrystallization to room temperature by water.
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