Background technology
Ferrous materials is as most important structured material, and improve intensity is that an urgent demand to its proposition is used in market always.The strength level (tensile strength) of general carbon steel reaches as high as about 600MPa, and low alloy steel can reach about 800MPa; Special process means such as special elementses such as Nb is added in employing, V and employing controlled rolling can be brought up to intensity about 1000MPa.Obtain more high-intensity ferrous materials, except strengthening alloying level (this can increase cost undoubtedly), mainly rely on modifier treatment.But well-known limitation such as modifier treatment has energy consumption and production cost is higher, the difficult control of quality product.Therefore, the intensity that further improves low alloy steel under without the condition of modifier treatment just has crucial meaning.
Carbon is the most important and cheap strengthening element of ferrous materials.But the increase of carbon content can influence plasticity, and by traditional idea, carbon content is increased to and can makes plasticity be reduced to the degree that structured material can't use more than 1%; Simultaneously, serious fragility also makes intensity improve.The carbon content of non-hardened and tempered steel is all below 0.5% on the present market.Superhigh carbon steel (carbon content is 1% to 2.1%) is got rid of outside practical engineering materials for a long time.But, be that some U.S. metallurgists of representative but find with Sherby, organize abundant refinement and homogenizing, superhigh carbon steel can obtain the good mechanical property that high strength and certain plasticity match if make.
Yet, under traditional technology, realize that the structure refinement of superhigh carbon steel and homogenizing are very difficult.Because carbon content is very high, is difficult to avoid the segregation of carbon and the formation of thick carbide in the process of setting of conventional casting, this can cause the fatal fragility of material.In order to overcome this difficulty, Sherby has proposed a series of quite complicated operational paths, and obtains a collection of patent.The described method of these patents on the whole, all comprises two technological processs.The first, eliminate thick carbide and avoid the appearance of grain boundary carbide network with multi-pass hot-work; The second, thermal treatment that ins all sorts of ways or temperature processing or both combinations make carbide be distributed in matrix with fine particle form even dispersion.Fu Za technological process is difficult to utilize the existing means of production to realize like this.
1999, Sherby propose again the hot extrusion technique route (publish in " MetallurgicalAnd Materials Transaction ", Vol.30A, 1999, p1559.), specific as follows:
Vacuum-casting;
Carrying out two step high temperature-middle warm forgings makes: the first step: rise and forge 1100 ℃, 900 ℃ of finish-forgings;
Second step: rise and forge 900 ℃, 700 ℃ of finish-forgings;
Under 900 ℃ or 1025 ℃ or 1150 ℃, carry out hot extrusion (need are packed blank in the mild steel jar that size matches into before the extruding).
This technology is more complicated still, and senior middle school's warm forging is brought up needed for two steps, but also needs the large-tonnage heat extruder, the energy consumption height, and industrial scale is difficult to enlarge.
The applicant once proposed a kind of new superhigh carbon steel production technique, its operational path is: obtain blank with reaction-injection moulding, then blank is implemented isothermal forging, need not modifier treatment behind the air cooling can obtain yield strength reaches~900MPa, tensile strength reaches~1200MPa, and unit elongation reaches~10% superhigh carbon steel material.(to this spray deposition processing, the applicant's patent applied for, number of patent application: 01126952.9)
This operational path is than obviously simplification in the past, but needs use isothermal forging equipment, and productivity is low, thereby still is restricted on range of application and industrial scale.Though,, should seek an operational path that can utilize the common means of production from being convenient to carry out the angle of scale production aspect the special nearly end form goods of direct preparation shape its irreplaceable advantage being arranged.
Summary of the invention
The objective of the invention is to provide a kind of method of simply producing superhigh carbon steel efficiently, be convenient to realize scale production, and will make the material that obtains have higher intensity and the necessary plasticity of maintenance.
For achieving the above object, technical solution of the present invention is,
A kind of high strength superhigh carbon steel,
(1) its alloying constituent:
C:?????1.0~2.0;
Cr:????0.5~2.0;
Mn:????0.2~0.8;
A kind of among Si and the Al;
Surplus Fe;
More than be weight percentage;
(2) obtain blank with spray deposition processing
As raw material, adopt spray deposition processing to obtain blank the alloying constituent in (1);
(3) the reaction-injection moulding blank is carried out hot rolling.
Wherein, to the restriction of the foreign matter content among the Fe, only require the standard that reaches general carbon steel; The interpolation of Mn is in order to suppress the harmful effect of trace elements such as S, P; The interpolation of Cr is for fear of greying, suppresses growing up of carbide particle in the technological process simultaneously.
Interpolation can improve the element of superhigh carbon steel high temperature deformation ability: Si and Al;
In C content is 1.0~1.5wt% scope, should add Si, Si content is: 0.5~3.5wt%;
In C content is 1.5~2.0wt% scope, should add Al, Al content is: 0.5~2.0wt%;
This be because: Si has and suppresses the good action that the grain boundary carbide network forms, but Si is easier to cause greying than Al, and is especially serious under C content condition with higher; Simultaneously, along with the raising of Si content, the maximum solid solution degree of C in austenite descends, and the superfluous carbide network that causes thus is difficult to be eliminated by simple thermal treatment.
The existence of Al does not reduce the solid solubility of C in austenite in the mentioned component scope, and the carbon concentration of raising eutectoid transformation point, therefore under high C content, can avoid the appearance of primary carbide, in addition, even the proeutectoid carbide network occurs, also eliminate with simple thermal treatment easily.Experiment is proof also, and Al can obviously improve the high temperature deformation ability of superhigh carbon steel, increases deflection, reduces deformation stress.
Optimal components proportioning (weight percent):
Fe-Si-Cr system:
C:??????1.1~1.4
Si:?????2.0~3.0
Cr:?????1.4~1.7
Mn:?????0.4~0.7
Surplus Fe.
Fe-Al-Cr system:
C:??????1.5~1.8
Al:?????1.0~1.8
Cr:?????1.4~1.7
Mn:?????0.4~0.7
Surplus Fe.
The wherein hot rolling described in (3):
Heating temperature: 760 ℃~1100 ℃;
Rolling deformation speed: 1/s~10/s;
Rolling draught: 50%~70%.
Be material good mechanical properties after the acquisition hot rolling, should heat by following temperature range:
Fe-Si-Cr system: 820 ℃~920 ℃, draught is more than 50%, can obtain material good mechanical properties after the hot rolling;
Fe-Al-Cr system: 900 ℃~1000 ℃, draught reaches 70%, can obtain material good mechanical properties after the hot rolling.
A kind of production technique of high strength superhigh carbon steel comprises following steps,
(1) alloying constituent:
C:????1.0~2.0;
Cr:???0.5~2.0;
Mn:???0.2~0.8;
A kind of among Si and the Al;
Surplus Fe;
More than be weight percentage;
(2) obtain blank with spray deposition processing
As raw material, adopt spray deposition processing to obtain the alloying constituent in the step (1)
Blank;
(3) the reaction-injection moulding blank is carried out hot rolling.
The wherein hot rolling described in the step (3):
Heating temperature: 760 ℃~1100 ℃;
Rolling deformation speed: 1/s~10/s;
Rolling draught: 50%~70%.
Described hot rolling Heating temperature: 900 ℃~1000 ℃, draught reaches 70%.
Wherein to be that a time is rolling finish above-mentioned draught to the hot rolling described in (3).
Wherein blank is put into the process furnace that reaches preset temperature before the hot rolling described in the step (3), be incubated under institute's fixed temperature, soaking time determines according to sotck thinkness, promptly every millimeter 2 minutes.
The process of spray deposition processing: the mother alloy material is put into the induction furnace internal heating, make it fusing, keep for some time being higher than under 150~250 ℃ of temperature of fusing point; Make the temperature and the composition of melt reach even.To by the effusive melt jet of catheter, make it to be atomized into fine drop with high pressure nitrogen, fly and be deposited on and collect on the substrate, finish and solidify and form block.Experiment shows that thus obtained reaction-injection moulding base material has the high temperature deformation ability of the unexistent excellence of general alloy material.To this, the applicant's patent applied for, number of patent application: 01126952.9;
Its singularity is two aspects: once being can directly obtain the stretch percentage elongation more than 100% through special super plastics processing (thermal treatment or mechanical treatment or both combinations); The 2nd, under quite high rate of deformation (10
-2/ s or higher) (and general superplastic alloy material is usually 10 stretch percentage elongation more than 100% still can
-4Has high-elongation under the low rate of deformation about/s).Experimental result sees Table 1.This result also shows, contains the Al superhigh carbon steel, although carbon content is higher, still has good plastic deformation ability, its deformation stress be lower than carbon content lower contain the Si superhigh carbon steel.
The stretch percentage elongation of table 1. reaction-injection moulding ultrahigh carbon steel base material under 850 ℃ and deformation speed
Rate of deformation | 1.22C-2.98Si-1.47Cr-0.66Mn-surplus Fe | 1.71C-1.46Al-1.44Cr-0.44Mn-surplus Fe |
?5×10
-3/s
| Unit elongation: 232% (deformation stress: 100MPa) | Unit elongation: 183% (deformation stress: 76MPa) |
?1×10
-2/s
| Unit elongation: 175% (deformation stress: 119MPa) | Unit elongation: 107% (deformation stress: 103MPa) |
?1×10
-1/s
| | Unit elongation: 120% (deformation stress: 142MPa) |
By The above results as can be known, reaction-injection moulding superhigh carbon steel blank has excellent high temperature deformation ability, therefore can implement aximal deformation value hot-work.
In addition, experiment shows that also above-mentioned reaction-injection moulding superhigh carbon steel can implement that the hot worked temperature range of aximal deformation value is wide to reach 790 ℃~1000 ℃; The lowest temperature of the Fe-Si-Cr system that wherein, carbon content is lower also can expand to 760 ℃.
The reaction-injection moulding blank is carried out hot rolling
(1) before rolling blank is put into the process furnace that reaches preset temperature, be incubated under institute's fixed temperature, soaking time determines according to sotck thinkness, promptly every millimeter 2 minutes.
Heating temperature: 820 ℃~1100 ℃, can realize that a time hot rolling up to 70% draught crackle does not take place.Be material good mechanical properties after the acquisition hot rolling, should heat by following temperature range:
Fe-Si-Cr system: 820 ℃~920 ℃
Fe-Al-Cr system: 900 ℃~1000 ℃
(2) above-mentioned blank is carried out hot rolling:
It is rolling to be fetched into beginning from process furnace, should make the blank temperature fall within≤100 ℃ scope; When Heating temperature is low (Fe-Si-Cr system), should make rolling temperature be not less than 760 ℃.
Rolling deformation speed: 1/s~10/s
Rolling draught: 50%~70%
To Fe-Si-Cr be: draught reaches more than 50%, can obtain material good mechanical properties after the hot rolling;
To Fe-Al-Cr be: draught need reach 70%, can obtain material good mechanical properties after the hot rolling;
Rolling the finishing of above-mentioned draught a time;
Rolling back air cooling is to room temperature.
Beneficial effect of the present invention
Adopt reaction-injection moulding+hot rolled method on the operational path of the present invention, the rolling back material that obtains
(1) do not find crackle after a time 50%~70% draught hot rolling;
(2) rolling back density obviously improves, and shows that the rolling material compactness extent that makes improves; The rolling defectives such as small spaces that may exist in the reaction-injection moulding blank of having eliminated of aximal deformation value.Density measurement the results are shown in Table 2;
(3) after the hot rolling material organize very evenly fine and closely woven;
(4) material that obtains after the hot rolling without any thermal treatment or mechanical treatment, can reach following room-temperature mechanical property:
Yield strength: more than the 1000MPa;
Tensile strength: more than the 1200MPa; Under certain processing condition, can reach 1300MPa~1400MPa;
Unit elongation: 8~11%.The density measurement result of table 2 superhigh carbon steel (the surplus Fe of 1.78C-1.46Al-1.61Cr-0.52Mn-)
The reaction-injection moulding blank | ????7.6463g/cm
3 |
970 ℃ of heating and hot rolled blank not | ????7.6526g/cm
3 |
970 ℃ are heated and hot rolling 70% back base | ????7.7851g/cm
3 |
Embodiment
Embodiment 1
1. alloying constituent (chemical analysis results): the surplus Fe of 1.24C-2.55Si-1.55Cr-0.62Mn-(wt%)
2. reaction-injection moulding
Concrete parameter is: the mother alloy material is put into crucible melt, the superheating temperature of liquation is about 150 ℃; The internal diameter of catheter is 4mm; The pressure of atomizing gas (nitrogen) is 2.2MPa, and spraying gun is 360mm to distance between substrate, and the substrate speed of rotation is 10rpm; Gas/liquid inventory is about 0.30M than (G/M)
3/ kg.
Produce thick 16 millimeters band sample from the reaction-injection moulding blank, front end is made wedgewise, so that nip when rolling.
3. hot rolling
Said sample put into respectively be heated to 820 ℃ in advance, insulation is 35 minutes in 850 ℃ the stove.
Taking out and to send into a maximum rolling force immediately behind the sample hot rolls that is 3000KN is rolled.It is rolling to be fetched into beginning from sample, 40 ℃~50 ℃ of specimen temperature declines (being measured by the infrared temperature tester).
The Kun diameter that rolls of milling train is: 370 millimeters; Rotating speed is: 24 rev/mins.
820 ℃, each one of 850 ℃ of heating sample is rolled to 8 millimeters by 16 millimeters a time respectively, draught 50%, and rolling speed is~6/s.
Again, 820C, each one of 850 ℃ of heating sample is rolled to 4.8 millimeters by 16 millimeters a time respectively, draught 70%, rolling speed is~7/s.
More than the rolling back of each sample air cooling to room temperature.
4. obtain material room temperature tensile property (table 3):
Table 3 reaction-injection moulding superhigh carbon steel (the surplus Fe of 1.24C-2.55Si-1.55Cr-0.62Mn-) hot rolling
After the room temperature tensile performance
Heating temperature | Rolling reduction | Yield strength | Tensile strength | Unit elongation |
????820℃ | ????50% | ??1016MPa | ??1230MPa | ????10.8% |
????70% | ??1108MPa | ??1289MPa | ????10% |
????850℃ | ????50% | ??1081MPa | ??1295MPa | ????10.3% |
????70% | ??1114MPa | ??1298MPa | ????10.5% |
Embodiment 2
1. alloying constituent (chemical analysis results): the surplus Fe of 1.78C-1.46Al-1.61Cr-0.52Mn-(wt%)
2. reaction-injection moulding, concrete parameter is with embodiment 1.
Produce thick 16 millimeters band sample from the reaction-injection moulding blank, front end is made wedgewise, so that nip when rolling.
3. hot rolling
Said sample put into respectively be heated to 910 ℃ in advance, insulation is 35 minutes in 970 ℃ the stove.
Taking out and to send into a maximum rolling force immediately behind the sample hot rolls that is 3000KN is rolled.It is rolling to be fetched into beginning from sample, 70 ℃~90 ℃ of specimen temperature declines (being measured by the infrared temperature tester).
The milling train condition is with embodiment 1.
910 ℃, each one of 970 ℃ of heating sample is rolled to 4.8 millimeters by 16 millimeters a time respectively, draught 70%, and rolling speed is~7/s.
More than the rolling back of each sample air cooling to room temperature.
4. obtain material room temperature tensile property (seeing Table 4):
Table 4 reaction-injection moulding superhigh carbon steel (the surplus Fe of 1.78C-1.46Al-1.61Cr-0.52Mn-) hot rolling
After the room temperature tensile performance
Heating temperature | Rolling reduction | Yield strength | Tensile strength | Unit elongation |
????910℃ | ????70% | ??1075MPa | ??1324MPa | ????8.3% |
????970℃ | ????70% | ??1068MPa | ??1419MPa | ????8.8% |
Other embodiment test-results 1. alloying constituents (being shown in Table 5) 2. the concrete parameter of spray deposition processing with embodiment 13. complete processings (being shown in Table 5)
Other embodiment test-results of table 5
Embodiment | Alloying constituent (%) | Heating temperature | Rolling reduction | Yield strength | Tensile strength | Unit elongation |
????3 | 1.17C-2.99Si-1.57Cr-0.57Mn-surplus Fe | ?820℃ | ?70(%) | 1074MPa | ?1294MPa | ?9(%) |
????4 | 1.10C-2.85Si-1.42Cr-0.55Mn-surplus Fe | ?850℃ | ?70(%) | 1119MPa | ?1290MPa | ?8.7(%) |
????5 | 1.61C-1.59Al-1.47Cr-0.57Mn-surplus Fe | ?910℃ | ?70(%) | 1109MPa | ?1311MPa | ?7.8(%) |