CN100519816C - Ultra-fine ferrite crystal grain low-alloy steel and manufacturing method thereof - Google Patents
Ultra-fine ferrite crystal grain low-alloy steel and manufacturing method thereof Download PDFInfo
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Abstract
The present invention discloses one kind of low alloy steel with superfine ferrite crystal grain and its producing process. The low alloy steel has the components including C 0.02-0.20 wt%, Mn 0.40-1.6 wt%, C+Mn/6+(Cu+Ni)/15 +(Cr+Mo+V)/5 0.20-0.40 wt%, Nb 0.01-0.04 wt%, Ti 0.008-0.020 wt%, Ti/N 2.0-3.0 wt%, Si not more than 0.50 wt%, and Fe for the rest. Its production process includes fast heating at speed over 5 deg/s, once cyclic in-situ alpha-to-gamma-to-alpha phase change, once cyclic strain induced alpha-to-gamma phase change, cooling at speed over 10 deg/s while strain induced gamma-to-alpha phase change to obtain superfine ferrite crystal grain smaller than 3.0 micron.
Description
Technical field
The present invention relates to a kind of low alloy steel and manufacture method thereof, specially refer to a kind of thermal processing method that obtains ultra-fine ferrite crystal grain in containing the Nb low-carbon low-alloy steel, ferrite crystal grain can refine to below the 3.0 μ m.
Background technology
As everyone knows, low-carbon (LC) (high strength) low alloy steel is one of most important structural timber, is widely used among petroleum natural gas pipeline, ocean platform, shipbuilding, bridge, pressurized vessel, building structure, automotive industry, transportation by railroad and the machinofacture.Low-carbon (LC) (high strength) low alloy steel performance depends on the process system of its chemical ingredients, manufacturing processed, and wherein intensity, toughness and weldability are the most important performances of low-carbon (LC) (high strength) low alloy steel, and its final decision is in the microstructure state of finished steel.The refinement ferrite grain size is unique measure that can improve intensity and toughness simultaneously and improve the weldability of steel, is the most important method for toughening of low-carbon (LC) (high strength) low alloy steel, is the target that the metallurgical engineer pursues for many years always.
The super-steel of new generation that turns to sign with crystalline grains ultra is researched and developed in the world major industrialized country and just is surging forward.Japan has begun the national research project of " new millennium structured material (or super-steel iron material) " in April, 1997,10 years by a definite date.The same year MITI of Japan's basic industry office to have arranged by Japanese five big steel companies again be key " super metal " development project, target is by new operational path, the boundary that metal microstructure is controlled at superfine crystal particle sees yardstick, plans to form in 5 years " the control manufacturing technology of iron Jie Guan field microstructure ".Under the influence of Japanese super-steel project, Korea S started the national project of " 21 century high performance structures steel " in 1998, and 10 years by a definite date, this was to be the national project of main body by POSCO, and target class is similar to Japan.Under the influence of Japanese Korea S, China has started " the great fundamental research of ferrous materials of new generation " in 1998, and is listed in one of 10 projects of " 973 " first startup, and target is similar to Japan and Korea S equally.European Union has started " Ultrafine Grained Steel " project July calendar year 2001, participated in by the relevant research institution of states such as Italy, Germany, Britain, Sweden and Belgium, and some associated companies in Europe are also advanced from industry member simultaneously.
More than the research project of Qi Donging all has a common core objective, promptly realizes the microstructure super-refinement, all obtaining ultra-fine ferrite crystal grain as most important research direction, makes every effort to the commanding elevation of preemption techniques.
(Thermo-mechanical controlprocess is handled in the novel heat machinery control that has developed since the eighties, abbreviation TMCP) steel has very big advantage than (high strength) low alloy steel of pair rolling attitude (as-rolled), these steel have very tiny ferrite/bainite tissue (its ratio depends on chemical ingredients and fabrication process condition), thereby demonstrate good intensity and toughness, niobium suppresses austenite recrystallization and grain growth in the controlled rolling process, often be added into and be used for improving intensity and low-temperature flexibility in the TMCP steel, the ferrite grain size scope of the minimum of commercial TMCP steel is at 3～5 μ m, and there is very big difficulty in the size that further reduces ferrite crystal grain.
Recently in the national research project of " new millennium structured material (or super-steel iron material) "; research to ferrite (α) grain ultrafining of soft steel is very active; under the laboratory scale condition, having obtained grain-size is the superfine crystal particle ferritic structure of 1 μ m.The method that superfine crystal particle obtains roughly is divided into two classes, i.e. phase transition method and recrystallize method two classes.If the method that will obtain ultra-fine ferrite crystal grain is carried out exhaustive division, phase transition method is included in the processing that surpasses under cold austenite (γ) state and phase transformation and austenite/ferrite dynamic phase trasnsition again and reaches at (γ+α) the processing and the phase transformation in two-phase zone.The phase transition method common feature all is to suppress down and adopt at low temperature austenite region deformation processing (percentage pass reduction〉50%) with a passage.
The Yada of company of for example Japanese Nippon Steel and co-workers thereof have adopted a kind of new controlled rolling technology, promptly obtain the microstructure of superfine crystal particle by deformation induced ferritic dynamic phase trasnsition and dynamic recrystallization, they adopt a kind of thermal deformation simulated experiment and actual rolling test subsequently to the low alloy steel of 0.1%C～1.0%Mn composition system, have obtained the superfine crystal particle (US Patent4466842) less than 3 μ m.The recrystallize rule is utilized the recrystallize after martensite and bainite are suppressed down, has successfully developed the superfine crystal particle ferritic structure.More than invention is all adopted in low temperature supercooled austenite district or metastable martensite, bainite district are suppressed rolling down (percentage pass reduction〉50%) with a passage.So high percentage pass reduction and low deformation temperature will cause huge deformation drag and high mill load, are difficult to realize in actual production; Its next passage is suppressed down the ununiformity of deformation, the ununiformity that will cause final phase transformation/recrystallized structure, deformed belt, the original austenite crystal prevention zone of strain high concentration, mechanical twin band that position in deformed set such as high density dislocation tangle, form ultra-fine crystalline substance by strain-induced transformation/recrystallize easily, and other position grain-size thicker (5 μ m～10 μ m), cause the ununiformity of tissue, therefore realize that the difficulty of the big test specimenization of industrial production is bigger.
Chinese patent application 03129488.X discloses " ultra-fine ferrite crystal grain contain Nb low-carbon low-alloy steel and manufacture method thereof ", this patent based on by quick induction heating or test specimen energising direct heating (〉=15 ℃/s) and quicken controlled chilling (〉=10 ℃/s) realize austenite/ferrite circulating phase-change (
), and be combined in austenite non-recrystallization district accumulative total and depress deformation (round-robin accumulative total draft 〉=40% greatly, percentage pass reduction 〉=15%) acting in conjunction of the strain-induced transformation that causes realizes the ferrite crystal grain super-refinement, obtains the ferrite crystal grain of＜3.0 μ m.Though this patent successfully realizes ultra-fine ferrite crystal grain, manufacturing process head, the technological process more complicated, the technology controlling and process level is had relatively high expectations, and technique controlling difficulty is bigger, and manufacturing cost is also higher relatively simultaneously.
Chinese patent application numbers 200410054129.7 discloses " obtaining the manufacture method of ultra-fine grain steel ", this patent is based on add an amount of nucleating agent in molten steel in casting process, and suitably cooperate with flash set technology, obtain tiny equiaxial as-cast structure, adopt the strain-induced transformation technology again (promptly at Ar
3Near the some temperature, carry out continuously non-recrystallization controlled rolling, control accumulative total draft 〉=80%, percentage pass reduction 〉=15% makes austenite generation strain inducing dynamic phase trasnsition) obtain the ferrite crystal grain of＜3.0 μ m.Though this patent is represented the developing direction of following Ultrafine Grained Steel, technical have a very strong suitability and perspective, production cost is also lower, but the process control difficulty that nucleating agent is joined in the molten steel that is solidifying effectively is bigger, the suitable nucleating agent of quantity granularity is in molten steel in the disperse distribution, it is bigger also will to keep molten steel to have the good mobility difficulty, also needs to research and develop the adding equipment and the operating device of special outer planting nucleating agent in addition.
Summary of the invention
The object of the present invention is to provide strain-induced transformation to obtain ultra-fine ferrite crystal grain low-alloy steel and manufacture method thereof, can obtain＜ultra-fine ferrite crystal grain of 3.0 μ m; And cheap for manufacturing cost, technological process is relatively simple, and than being easier to realize suitability for industrialized production.
For achieving the above object, technical scheme of the present invention is, based on the rapid heating that adopts 〉=5 ℃/s (recommend to adopt induction heating or directly energising heat) and 〉=accelerated cooling process of 10 ℃/s, and, promptly at first carry out a α → γ → α circulation original position phase transformation in conjunction with once circulate original position phase transformation and a cyclic strain induced transformation; And then carry out the cyclic strain induced transformation one time, promptly in heat-processed, work as temperature and arrive Ac
3In the time of near the some temperature, carry out continuously deformation, strain inducing α → γ phase transformation; In process of cooling, work as temperature and arrive Ar
3In the time of near the some temperature, carry out continuously deformation, strain inducing γ → α phase transformation, the ultra-fine ferrite crystal grain of acquisition＜3.0 μ m.
Ultra-fine ferrite crystal grain low-alloy steel, its composition quality per-cent is:
0.02≤C≤0.20
0.40≤Mn≤1.6
0.20≤【C+Mn/6+(Cu+Ni)/15+(Cr+Mo+V)/5】≤0.40
0.01≤Nb≤0.04
0.008≤Ti≤0.020
2.0≤Ti/N≤3.0
Si≤0.50
Surplus is Fe and inevitably is mingled with; Wherein, also comprise in Cu≤0.30, Ni≤0.30, Cr≤0.15, V≤0.10 one or more, Mo is zero.
Further, its composition quality per-cent is,
0.05≤C≤0.15
0.80≤Mn≤1.3
0.26≤【C+Mn/6+(Cu+Ni)/15+(Cr+Mo+V)/5】≤0.36
0.015≤Nb≤0.030
0.010≤Ti≤0.015
2.0≤Ti/N≤3.0
Si≤0.50
Surplus is Fe and inevitably is mingled with;
Wherein, also comprise in Cu≤0.30, Ni≤0.30, Cr≤0.15, V≤0.10 one or more, Mo is zero.
The manufacture method of ultra-fine ferrite crystal grain low-alloy steel of the present invention, it comprises the steps:
1) smelts, is cast as slab by mentioned component;
2) at first adopt cycle heat treatment one time, rate of heating 〉=5 ℃/s, soaking temperature are controlled between the T1+10 ℃～T1+20 ℃, soaking time t=thickness of slab * 30s/mm～60s/mm; Thickness of slab is in mm, and (small specimen takes off limit, big test specimen capping), purpose is to guarantee the complete solid solution of Nb element, and is rolling to realize follow-up strain-induced transformation; Be cooled to the Ar1 point below the temperature with 〉=10 ℃/s speed of cooling immediately, wherein T1=5833/{1.63-log[%Nb * (%C+12 * %N/14)] }-273.15;
3) as temperature arrival Ar
1After the some temperature, the rate of heating with 〉=5 ℃/s quickly heats up to Ac immediately
3-50 ℃ of some temperature, and at Ac
3-50 ℃～Ac
3Carry out continuously deformation in the temperature range, percentage pass reduction 〉=12%, accumulative total draft 〉=60%, the deformation end temp is Ac
3Near the some temperature; Ac wherein
3(℃)=910-203[%C]
1/2+ 44.7[%Si]-15.2[%Ni]+31.5[%Mo]+104[%V]+13.1[%W]-(30[%Mn]+11[%Cr]+20[%Cu]-700[%P]-400[%Al]-120[%As]-400[%Ti]);
4) after deformation is finished, be quickly cooled to Ar with 〉=10 ℃/s speed of cooling immediately
3+ 50 ℃ of some temperature, and at Ar
3+ 50 ℃～Ar
3Carry out continuously deformation in the temperature range, percentage pass reduction 〉=10%, accumulative total draft 〉=60%, the deformation end temp is Ar
3The point temperature;
5) after deformation is finished, be quickly cooled to room temperature with 〉=10 ℃/s speed of cooling immediately can obtain＜3 μ m ferrite crystal grains; Ar wherein
3(℃)=910-273[%C]-74[%Mn]-5[%Cu]-16[%Cr]-57[%Ni]-9[%Mo].
Physical metallurgy analysis of the present invention
For α → γ → α circulation original position phase transformation of adopting rapid heating and accelerated cooling process, by induction heating or direct-fired being rapidly heated of switching on (rate of heating 〉=5 ℃/s), realize up-quenching (up-quenching) technological process, form tiny and uniform austenite crystal.As everyone knows; when ferritic structure by up-quenching to the austenite phase region; promptly be heated to the austenite phase region with rate of heating fast; because rate of heating is very fast; ferrite crystal grain can not grown up substantially, and the chemical ingredients of ferritic phase does not change substantially yet, thereby causes the huge phase driving force of α → γ; greatly improve the nucleation rate of austenite nucleus, the refine austenite grain-size.Secondly, the austenite nucleus of forming core have four crystal degrees to, i.e. (111), (1-11), (11-1), (111), and these four crystal degrees are high-angle boundaries to the crystal boundary that intergranule forms, therefore can cut apart former ferrite crystal grain effectively at the ferrite crystal boundary or at the austenite crystal that ferrite intracrystalline forming core is grown up, form tiny and uniform austenite crystal, as shown in Figure 1.Equally, crossed apace when austenite and to be as cold as the ferrite phase region, because huge γ → α phase driving force, greatly increased the nucleation rate and the nucleation site of ferrite nucleus, thus greatly refinement ferrite crystal grain; In addition, the ferrite crystal grain of forming core have (110) and (1-10) two crystal degrees to, and these 2 crystal degrees also are high-angle boundaries to the crystal boundary that intergranule forms, therefore the ferrite crystal grain that forming core is grown up at austenite grain boundary or in austenite crystal also can be cut apart original austenite grain effectively, form tiny and uniform ferrite crystal grain, as shown in Figure 2.
Tiny ferrite crystal grain is by (〉=5 ℃/s) be warming up to (Ac of rapid heating
3-50 ℃) some temperature near after, immediately at (Ac
3-50 ℃)～Ac
3Carry out successive deformation in the temperature range,, can obtain superfine little austenite crystal by strain inducing α → γ phase transformation.When at (Ac
3-50 ℃)～Ac
3When carrying out successive deformation in the temperature range, tiny ferrite crystal grain constantly is out of shape repeatedly, and serious Plastic Deformation rheology at first causes ferrite crystal grain to elongate and draw down along the deformation direction.Because ferrite crystal grain is tiny, strain mainly concentrates on former ferrite crystal boundary near zone, and the quantity that the deformed belt of ferrite intracrystalline forms is then less, and this has reduced the ununiformity of strain distribution greatly, and strain is distributed among the crystal grain equably.These strains mainly exist with the form of highdensity crystal boundary step, grain boundary dislocation, they are the most favourable nucleation sites of austenite, embodied constantly and had high nucleation rate by the strain ferrite, form tiny austenite crystal, promptly in (Ac3-50 ℃)～Ac3 temperature range, superfine little austenite crystal changes by strain inducing dynamic alpha → γ, mainly forms on the ferrite crystal boundary that is elongated, form a large amount of steps.After phase transformation finished, just the austenite crystal that comes from ferritic transformation was lower than Ac owing to being in
3In the some temperature range and unstable, will very fast disappearance with the ferritic answer of deformation, the austenite that forms by strain-induced transformation reverses by γ → α again and is deformed into ferrite.So change ground by the α → γ → α that moves in circles and take place repeatedly, conformal alternating temperature degree reaches Ac
3Point, austenite/ferrite crystal grain can finally be formed superfine little uniform austenite crystal by continuously refinement.Along with temperature arrives Ac
3The point temperature is also followed finishing of deformation, and test specimen is quickly cooled to (Ar immediately
3+ 50 ℃) the some temperature, superfine little austenite crystal is by cooling off fast (〉=10 ℃/s) be cooled to (Ar
3+ 50 ℃) near the temperature spot, and (Ar
3+ 50 ℃) carry out deformation near the temperature spot, by strain-induced transformation, can obtain ultra-fine ferrite crystal grain.Promptly ought be in (Ar
3+ 50 ℃) when temperature spot was neighbouring, when superfine little austenite crystal was deformed, serious Plastic Deformation rheology was at first brought out austenite crystal and is elongated along rolling direction.Because austenite crystal is tiny, strain mainly concentrates on original austenite crystal prevention near zone, mechanical twin circle near zone, the quantity that the deformed belt of intracrystalline forms is then less, and this has reduced the ununiformity of strain distribution greatly, and strain is distributed among the crystal grain equably.In contrast, when thick austenite crystal deformation, strain distribution is extremely inhomogeneous, and main concentrating is distributed among the part crystal grain, concentrates to be distributed among the intracrystalline deformation band; During secondly tiny austenite crystal deformation, strain stores can be higher; On the contrary, during thick austenite crystal deformation, strain stores can be relatively low.Continuation along with deformation, the increase of accumulative total dependent variable, at austenite grain boundary, twin boundary near zone, because coordination does not retrain and different slip system starts simultaneously mutually to intergranule, dislocation with as " source " of dislocation and the crystal boundary generation complex interactions of " well ", form a large amount of steps on original austenite crystal prevention, annealing twin circle, this step is the best nucleation site of ferrite crystal grain, because the energy barrier of forming core is minimum on step.Along with austenite plastic deformation degree strengthens (accumulative total draft 〉=60%) unceasingly, it (is that deformation makes Ar that the strain inducing dynamic phase trasnsition will take place effectively
3Move on the some temperature, γ → α phase transformation is taken place at the austenite phase region).At Ar
3On the transition temperature, superfine little ferrite crystal grain changes by the dynamic γ of strain inducing → α, mainly forms on the austenite grain boundary that is elongated, form a large amount of steps, mechanical twin circle.After phase transformation finishes, just the ferrite crystal grain that comes from austenitic transformation is in and is higher than in the Ar3 point temperature range, promptly be in the austenite phase region, this ferrite is unsettled, will very fast disappearance with the austenitic answer of deformation, promptly the ferrite that forms by strain-induced transformation reverses by α → γ again and is deformed into austenite.So change ground generation repeatedly by γ → α and the α → γ that moves in circles, conformal alternating temperature degree is near Ar
3Point, austenite/ferrite crystal grain can be by continuously refinement, and final ultra-fine ferrite crystal grain forms, and is quickly cooled to room temperature immediately, grows up to prevent ultra-fine ferrite crystal grain, and technology is by shown in Figure 3.
Beneficial effect of the present invention
At first, the present invention has avoided at high rolling pass draft and rolling under extremely low deformation temperature, and the deformation drag of milling train and load are reduced common controlled rolling scope, and making the ordinary hot milling train produce ultra-fine crystalline substance becomes possibility; Avoid a passage to suppress down the ununiformity of deformation simultaneously, eliminated the ununiformity of final phase transformation/recrystallized structure.
Secondly, the present invention avoided 3 austenite/ferrite cyclic strain induced transformations rolling (
) manufacturing process that technology caused big, the higher shortcoming of manufacturing cost of length, complex technical process, technique controlling difficulty.
Once more, avoided nucleating agent is joined the process control difficulty of solidifying in the molten steel, avoid making the suitable nucleating agent of quantity granularity in molten steel, to be in the disperse distribution, also will keep molten steel to have the difficulty of good mobility and equipment and the operating device that the special nucleating agent of needs research and development adds.Last manufacturing process of the present invention is fairly simple, technical process is short, manufacturing cost is also lower, realize large-scale production easily.
Description of drawings
Fig. 1 for former ferrite crystal grain by the different crystal degree to austenite crystal cut apart synoptic diagram;
Fig. 2 for original austenite grain by the different crystal degree to ferrite crystal grain cut apart synoptic diagram;
The process schematic representation that Fig. 3 forms for ultra-fine ferrite crystal grain of the present invention;
Fig. 4 is the electromicroscopic photograph of the embodiment of the invention 6 ultra-fine ferrite crystal grains.
Embodiment
Embodiment carries out alloy smelting referring to table 1 in 50 kilograms of vacuum induction furnaces, adopting more purified coinage steel is raw material.Smelt the strand that is cast into φ 150mm * 300mm after finishing, strand is at 1150 ℃ of bases that forge into 70 * 270 * length (mm), forge the back blank and advance the sandpit slow cooling, and sawing becomes the steel billet heat supply of thick 70 * wide by 135 * long 200 (mm) to roll the usefulness of simulation test to room temperature.
Strain inducing rolling technology of the present invention+ACC test and general T MCP technological test are all carried out on Gleeble 1500 thermal analogy machines, from forging base thickness 1/4, the cylinder sample of line cutting processing φ 20mm * 40mm, simulate the hot rolling test then on Gleeble 1500 type hot modeling test machines, concrete processing parameter and test-results are as shown in table 2.
According to the technology of the present invention, can be by a spot of scrap build, promptly increase an induction heating equipment or the heating installation of directly switching on, can in common hot continuous rolling system and 5000mm wide and heavy plate mill system, use, and can have induction heating, the hot continuous rolling steel mill that quickens cooling equipment and the popularization of Heavy Plate Production producer to all, because the production technique of the technology of the present invention is relatively simple, the process control ratio is easier to, and is a kind of production method of practicable superfine grain steel sheet.
Claims (4)
1. ultra-fine ferrite crystal grain low-alloy steel, its composition quality per-cent is:
0.02≤C≤0.20
0.40≤Mn≤1.6
0.20≤【C+Mn/6+(Cu+Ni)/15+(Cr+Mo+V)/5】≤0.40
0.01≤Nb≤0.04
0.008≤Ti≤0.020
2.0≤Ti/N≤3.0
Si≤0.50
Surplus is Fe and inevitably is mingled with;
Wherein, also comprise in Cu≤0.30, Ni≤0.30, Cr≤0.15, V≤0.10 one or more, Mo is zero.
2. ultra-fine ferrite crystal grain low-alloy steel as claimed in claim 1 is characterized in that,
0.05≤C≤0.15
0.80≤Mn≤1.3
0.26≤【C+Mn/6+(Cu+Ni)/15+(Cr+Mo+V)/5】≤0.36
0.015≤Nb≤0.030
0.010≤Ti≤0.015
2.0≤Ti/N≤3.0
Si≤0.50
Surplus is Fe and inevitably is mingled with;
Wherein, also comprise in Cu≤0.30, Ni≤0.30, Cr≤0.15, V≤0.10 one or more, Mo is zero.
3. the manufacture method of ultra-fine ferrite crystal grain low-alloy steel as claimed in claim 1 or 2, it comprises the steps:
1) smelts, is cast as slab by claim 1 or 2 described compositions;
2) at first adopt cycle heat treatment one time, rate of heating 〉=5 ℃/s, soaking temperature are controlled between the T1+10 ℃～T1+20 ℃, soaking time t=thickness of slab * 30s/mm～60s/mm, and thickness of slab is in mm; Be cooled to the Ar1 point below the temperature with 〉=10 ℃/s speed of cooling immediately, wherein T1=5833/{1.63-log[%Nb * (%C+12 * %N/14)] }-273.15;
3) as temperature arrival Ar
1After the some temperature, the rate of heating with 〉=5 ℃/s quickly heats up to Ac immediately
3-50 ℃ of some temperature, and at Ac
3-50 ℃～Ac
3Carry out continuously deformation in the temperature range, percentage pass reduction 〉=12%, accumulative total draft 〉=60%, the deformation end temp is Ac
3Near the some temperature; Ac wherein
3(℃)=910-203[%C]
1/2+ 44.7[%Si]-15.2[%Ni]+31.5[%Mo]+104[%V]+13.1[%W]-(30[%Mn]+11[%Cr]+20[%Cu]-700[%P]-400[%Al]-120[%As]-400[%Ti]);
4) after deformation is finished, be quickly cooled to Ar with 〉=10 ℃/s speed of cooling immediately
3+ 50 ℃ of some temperature, and at Ar
3+ 50 ℃～Ar
3Carry out continuously deformation in the temperature range, percentage pass reduction 〉=10%, accumulative total draft 〉=60%, the deformation end temp is Ar
3The point temperature;
5) after deformation is finished, be quickly cooled to room temperature with 〉=10 ℃/s speed of cooling immediately can obtain＜3 μ m ferrite crystal grains; Ar wherein
3(℃)=910-273[%C]-74[%Mn]-5[%Cu]-16[%Cr]-57[%Ni]-9[%Mo].
4. the manufacture method of ultra-fine ferrite crystal grain low-alloy steel as claimed in claim 3 is characterized in that, rapid heating adopts induction heating or directly energising heating.
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| CN103447737B (en) * | 2013-09-05 | 2015-07-08 | 阿尔特汽车技术股份有限公司 | Support structure for welding |
| CN104611531A (en) * | 2015-02-06 | 2015-05-13 | 桂林理工大学 | Heating method for refining austenite grains of 45 steel |
| CN104611529A (en) * | 2015-02-06 | 2015-05-13 | 桂林理工大学 | Heating method for refined 75# steel austenite grain |
| CN104611533A (en) * | 2015-02-06 | 2015-05-13 | 桂林理工大学 | Heating method for refined No.35 steel austenite grains |
| CN104611527A (en) * | 2015-02-06 | 2015-05-13 | 桂林理工大学 | Heating method for refined 65# steel austenite grain |
| CN107177783B (en) * | 2017-07-21 | 2018-09-14 | 东北大学 | A kind of Ultra-fine Grained martensite ferrite dual phase steel and its production technology with the distribution of bimodal ferrite crystal grain |
| CN111421049B (en) * | 2018-12-23 | 2022-03-08 | 南京理工大学 | Preparation method of dual-phase heterogeneous reinforced weldless box body |
| CN114807549A (en) * | 2022-04-27 | 2022-07-29 | 昆明理工大学 | Thermal deformation method for refining hot work die steel grains |
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