CN1107521A - High strength hot rolled steel plates and sheets excellent in uniform elongation after cold working and process for producing the same - Google Patents
High strength hot rolled steel plates and sheets excellent in uniform elongation after cold working and process for producing the same Download PDFInfo
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- CN1107521A CN1107521A CN 94102515 CN94102515A CN1107521A CN 1107521 A CN1107521 A CN 1107521A CN 94102515 CN94102515 CN 94102515 CN 94102515 A CN94102515 A CN 94102515A CN 1107521 A CN1107521 A CN 1107521A
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Abstract
The hot-rolled steel plate with 34-62 kgf/sq.mm tension strength after cold processing contains C (0.04-0.25%), N (0.0050-0.0150%), Ti (0.003-0.050%), uniformly diffused TiN particles of 1-3 micrometers (0.0008-0.015%), and carbon equivalent weight (0.1-0.45%) and is made up through heating blank of the steel plate to 1000-1300 deg.C, rolling, fine rolling at inversion point Ar3, and air cooling from at least 500 deg.C or winding at 500 deg.C and air cooling. The steel structure contains 5-20% pearlite phase.
Description
The ordinary construction that the present invention relates to after cold machining process, to have fabulous uniform elongation and high tensile strength with and welded construction with hot-rolled steel sheet and thin plate, and relate to the technology of this kind of production product.
In recent years along with the quality improvement of structural hot rolled steel plate and thin plate and the major progress of production technology, demand to product made from steel with fabulous plastic deformation ability increases day by day, particularly all the more so from the viewpoint of seismic design in construction industry and field of civil engineering, and require steel plate to have high strength, low yielding ratio and high uniform elongation.
For adapting to this requirement, for example in the open No.57-16118 of Kokai(Japanese unexamined patent, disclose the technology that a kind of production is used for the low yielding ratio electric-welded pipe of oil well, wherein the carbon content of pipe is increased to 0.26% to 0.48%, and the Kokai(Japanese unexamined patent is open) to disclose a kind of production carbon content that is used for be 0.10% to 0.20% high tensile, the electric-welded pipe technology of low yielding ratio to No.57-16119.In these two kinds of technologies, do not need the manufacturing of heat treated electric-welded pipe to finish by hot-rolled steel sheet or the thin plate of producing a kind of low yielding ratio, and when dependent variable is restricted the above-mentioned steel product of cold working, it is big that work hardening amount thus can not become.In addition, the Kokai(Japanese unexamined patent is open) a kind of technology that is used for good round steel pipe of production anti-seismic performance or square steel pipe has been proposed among the No.4-176818, this method is by no strain ferrite-pearlite double structure is carried out hot-work, its rate of cooling of control and heat-treat and realize after hot-work.But all above-mentioned technologies all greatly reduce productivity, and last technology has also reduced weldability significantly.Therefore, these technologies can not satisfy the requirement of industrial circle at present.
Except above-mentioned open file, the Kokai(Japanese unexamined patent is open) No.4-48048 discloses with the KoKai(Japanese unexamined patent) No.4-99248 discloses in order to be mingled with the technology of improving welding heat influence area toughness by disperse oxide in steel matrix.The particle size of the oxide inclusion in last patent disclosure text is 0.5 μ m or littler and (Ti, Nb) (Q, N) composite junction crystalline phase arranged.The particle size of oxide inclusion is 1 μ m or littler and have Ti(O, N) a composite junction crystalline phase in the one patent disclosure text of back.The technology of these patent disclosures all has in essence different with the present invention the dispersion phase aspect purpose.
In general, the higher steel capital of intensity demonstrates higher yield ratio and lower ductility, and its uniform elongation is reduced.Especially when steel being cold worked into round steel pipe, square steel pipe, shaped steel, sheet pile etc., because the influence of the work hardening that the processing strain causes, its uniform elongation will significantly reduce.
The present invention has successfully solved the problems referred to above, even and purpose of the present invention just provide it being cold worked into pipe, square tube, shaped steel, sheet pile and wait until that productivity still has superior uniform elongation after not reducing a kind of like this O-level and has high tensile (34kgf/mm at least
2) hot-rolled steel sheet and thin plate.
In order to achieve the above object, the present inventor carefully studied the Chemical Composition of steel and crystalline structure and the mechanical property that obtains thus between relation, relation between the mechanical property of the mechanical property of the cold worked steel of process and the steel of rolling state, or the like.Thus, the present inventor has obtained following understanding: with regard to ordinary construction with and steel for welded structures, the particularly maximum tensile strength that has that is used for construction industry and field of civil engineering be 34 to 62kgf/mm
2Hot-rolled steel sheet or thin plate, the tensile strength of hot-rolled state product (its uniform elongation reduces with the raising of tensile strength) is roughly consistent with relation and their relations after cold working between the uniform elongation, and the relation under two kinds of situations can be come approximate representation with same curve; Though hot-rolled state steel and cold work steel both demonstrate the increase along with N in the steel, intensity improves and the characteristic of uniform elongation reduction, but by further increasing Ti, even when steel has high intensity, also can recover uniform elongation, and can obtain high uniform elongation, above-mentioned relation no longer keeps at this moment.
This understanding can further specify as follows with reference to figure 2.
Fig. 2 is a graphic representation, and it is represented by hot-rolled state product made from steel and the resulting TS(tensile strength of cold work steel product (square steel pipe), kgf/mm
2) and the Elu(uniform elongation, relation %), used steel is a S-1(comparative example listed in the table 1), the S-2(comparative example), T-1(for example) and T-2(give an example), S-1, T-1 and T-2 press the production technique B shown in the table 2 production, S-2 presses production technique C production.Ti among the S-1 and the content of N all are lower than lower limit of the present invention.Though the N content among the S-2 within the scope of the present invention, the content of Ti is lower and be lower than lower limit of the present invention.In production technique C, final rolling temperature is lower and be lower than transition point Ar
3
In Fig. 2, with regard to the relation between TS and the Elu, hot-rolled state steel plate or the thin plate of S-1 demonstrate high TS and Elu.But along with the increase of TS, the square steel pipe of S-1 demonstrates the rapid reduction of Elu.
Under the situation of S-2, above-mentioned relation is more obvious.When TS was higher, hot-rolled state steel plate or thin plate demonstrated 10% or littler Elu, though they can demonstrate higher Elu when TS is low.The square tube made from cold working demonstrates 10% or littler Elu as a rule, and increases with TS Elu is further reduced.
In other words, under the situation of S-1 and S-2, the cold work steel product demonstrates the trend that Elu sharply reduces with the increase of TS.
In contrast, under the situation of T-1 and T-2, even hot-rolled state steel plate or thin plate demonstrate the characteristic that Elu also reduces hardly when TS increases.The cold production that obtains thus demonstrates its Elu the seldom reduction of degree, and the influence that increased by TS.
In other words, even contain the N of an amount of interpolation and the steel of the present invention of Ti demonstrates after cold working, along with the raising of tensile strength, the characteristic that uniform elongation also reduces hardly.A kind of TS of having particularly of the present invention is at least 47kgf/mm
2Steel can demonstrate effect of the present invention.As mentioned above, use and steel for welded structures as ordinary construction, steel of the present invention has remarkable performance.
Based on the above-mentioned fact, the present invention has reached purpose of the present invention, and theme of the present invention is to have 34 to 62kgf/mm after cold shaping
2Tensile strength and the high tensile hot rolled steel sheet and the thin plate of superior uniform elongation, above-mentioned steel plate and thin plate contain 0.040% to 0.25% C, 0.0050% to 0.0150% N and 0.003% to 0.050% Ti, contain 0.0008% to 0.015% simultaneously, mean sizes is by 1 μ m to 30 μ m and the TiN of disperse in steel matrix, and contain 0.10% to 0.45% carbon equivalent (WES), when preparation steel plate and thin plate, the slab that will contain mentioned component is heated to 1000 to 1300 ℃ hot-rolled temperature, rolled slab is being at least transition point Ar
3Temperature finish rolling, then the rolled products air cooling is formed its total amount to be converted to the area percentage be 5% to 20% perlite phase to being at least 500 ℃ temperature or thereby rolled products being batched and will batch in the tissue of product air cooling at steel in the temperature that is at least 500 ℃, theme of the present invention also is to produce the production technique of the said products.
Fig. 1 (A) represents a photomicrography picture (amplifying 400 times), illustrates with steel of the present invention (the T-2(middle portion in the table 4) steel, contains 15.2% perlite phase) metallographic structure of the planar section of the square tube produced.
Fig. 1 (B) represents a photomicrography picture (amplifying 400 times), illustrates with relatively using the steel (metallographic structure of the planar section of the square tube that the S-2 steel in the table 4 (thickness (t)=3.2mm) contains 4% perlite phase) is produced.
Fig. 2 represents various hot-rolled steel sheets and the tensile strength of square tube and the relation between the uniform elongation in the table 4.
Describe the present invention below in detail.
In the present invention, at first making a kind of C, 0.0050% to 0.0150% N, Ti of 0.003% to 0.050% by 0.040% to-0.25% with traditional production stage forms, the scope of its carbon equivalent (Ceq) is 0.10% to 0.45%, all the other are the alloy steel sheet billet of Fe and unavoidable impurities, it be by make through continuous casting such as the molten steel of the smelting furnace production of converter or electric furnace or molten steel made steel ingot and with steel ingot through just being rolled into.
In the present invention, the composition in the steel is stipulated as mentioned above that its reason is described as follows.
C is the important composition of the perlite total amount mutually in intensity and the structure of steel of decision steel.Be at least 34kgf/mm when having tensile strength
2Hot-rolled steel sheet or thin plate in the tissue of steel, contain the area occupied rate and be less than 5% perlite phase time, the uniform elongation after its cold shaping will significantly reduce.This is because perlite can guarantee the intensity of steel, prevents that dislocation desity from increasing, and can keep the plastic deformation ability.
In addition, be 20% or more perlite phase time when hot-rolled steel sheet contains the area occupied rate, the hardness of steel is increased, the plastic deformation ability reduces.In order to obtain thisly having its total amount and account for the structure of steel that the area percentage is 5% to 20% perlite phase, just need steel to contain at least 0.04% C.But, when the content of C surpasses 0.25%, can weaken the welding property of steel, so the upper limit of C content is defined as 0.25%.
The N that is added in the steel is dissolved in the ferritic matrix, and it can improve the intensity of steel and reduce the plastic deformation ability.But,, just form TiV when N adds fashionablely with Ti.This formation not only makes the N that is dissolved in the steel reduce, and the plastic deformation ability is improved, and its dispersion is strengthened steel.Therefore N is a kind of important element, and it gives steel with high intensity and big uniform elongation.
In order to give steel with this performance, the TiN disperse that just must make the average particle size particle size with 1 μ m to 30 μ m is in matrix, and it is 0.0008% to 0.015% that its total amount is converted by weight.In other words, when the average particle size particle size of TiN during less than 1 μ m, the disperse enhancement is just very ineffective.
Certainly, when the average particle size particle size of TiN surpasses 30 μ m, in the cold working process, between thick TiN particle and matrix, can produce buffer action.Consistent with the increase of plastic deformation, tiny crack can occur, and make the plastic deformation ability drop of steel thus.
In order to obtain above-mentioned TiN, the content of Ti is preferably in 0.003% to 0.050% the scope.
In addition, though the necessary amounts of N is at least 0.0050%, preferably be at least 0.0080%, when the content of N surpassed 0.0150%, enhancement was excessive, and uniform elongation is reduced.Therefore the upper limit of N content is defined as 0.0150%.In addition,, be preferably in adding Ti and in steel, add Al before, make it deoxidation in order in steel, to form above-mentioned TiN effectively.
The reason of in steel of the present invention, adding Ti as mentioned above, and its content is preferably 0.01% to 0.03%.
Carbon equivalent (Ceq) obtains (according to WES) by following formula:
Ceq＝C+Si/24+Mn/6+Ni/40+Cr/5+Mo/4+V/14。
Determining of the total amount of Ceq is relevant with intensity and weldability.When total amount is less than 0.10%, can not guarantee enough intensity.When total amount surpassed 0.45%, though can obtain high intensity, weldability was weakened.Therefore Ceq. is limited in 0.10% in 0.45% scope.
Steel can contain to be useful on and improves intensity and flexible effective ingredient, chooses a kind of element the component that can form from the V by 0.01% to 0.7% Si, 0.1% to 2.0% Mn, 0.05% to 1.0% Ni, 0.05% to 1.0% Cr, 0.02% to 0.5% Mo and 0.005% to 0.2% at least.
In addition, P that is contained in the plate slab of the present invention and S are the detrimental impurity that reduces the toughness of steel and weldability etc.Therefore, the content of the content of P and S is limited in 0.025% or still less respectively, and the content of P+S is limited in 0.04% or still less.
In addition, steel of the present invention can contain a kind of be used to improve intensity and flexible effective ingredient, can comprise the rare earth metal the lanthanon of Y at least from the REM(by 0.05% to 1.0% Cu, 0.005% to 0.05% Nb, 0.001% to 0.1% Al, 0.0005% to 0.0020% B, 0.0005% to 0.0070% Ca and 0.001% to 0.050%) choose in the component formed a kind of.
Its composition is adjusted at alloy steel sheet billet in the above-mentioned scope is heated to and is used for 1000 to 1300 ℃ of hot rolled and is rolled, the temperature at steel is at least transition point Ar then
3Shi Jinhang finish rolling.Resulting steel air cooling to the temperature that is at least 500 ℃, obtaining steel plate, or is batched resulting steel air cooling and air cooling to being at least under 500 ℃ the coiling temperature, to obtain hot rolled band.
The lower limit of the Heating temperature that hot rolling is used is defined as 1000 ℃, and improve and the reduction of plastic deformation ability with the intensity that prevents to be caused by following situation: according to the thickness of steel, the final rolling temperature of steel can be lower than transition point Ar
3; Its result will force ferrite wherein to be subject to processing, so the dislocation desity in the matrix increases.When the board briquette of steel surpasses 1300 ℃, the productivity of product will significantly descend owing to the oxidation of product.Therefore, its upper temperature limit is defined as 1300 ℃.Final rolling temperature is limited to is at least transition point Ar
3, its reason as mentioned above.In addition, for fear of the unnecessary raising of steel plate of the present invention and thin plate intensity, the air cooling starting temperature after rolling and coiling temperature be limited to be at least 500 ℃.
In steel plate produced according to the invention, will to have average particle size particle size be the good disperse of TiN of 1 μ m to 30 μ m and be deposited in the matrix, and its ratio is 0.0008% to 0.015%.Consequently, steel demonstrates a kind of close grain ferrite one pearlitic structure (part contains bainite structure), wherein contain just like shown in Fig. 1 (A), the conversion of its content is 5% to 20% perlite phase for the area percentage.Because steel plate of the present invention and thin plate have the tissue of this steel, they have superior uniform elongation after cold working, and have 34 to 62kgf/mm
2High intensity.
The following describes embodiments of the invention.
Having the plate slab that contains TiN of Chemical Composition shown in the table 1 and relatively all being rolled into thickness with steel is 3.0 to 22.2mm steel plate and thin plate, and the mechanical property of finished product steel plate is studied.Its production technique is illustrated in the table 2.Hot-rolled state or the performance that is machined to 10% strained product made from steel all are illustrated in the table 3.
The steel of table 4 and table 5 expression rolling state and with the performance study result at each position on its square tube of making.Fig. 1 (A) has represented the photomicrography (amplifying 400 times) with the metallographic structure of the planar section (middle part) of the square tube of steel T-2 manufacturing of the present invention, and Fig. 1 (B) represents the photomicrography with the metallographic structure of the same area of the square tube of relatively using steel S-2 to make.In the steel of the present invention in Fig. 1 (A), the content by area percentage conversion of perlite phase is approximately 15.2%, and relatively using in the steel in Fig. 1 (B), only contains the perlite phase that is about 4% minute quantity.Fig. 2 represents steel of the present invention and is used for the tensile strength of steel of comparison and the relation between the uniform elongation that they have mainly utilized the result in the table 4.
According to these results, though its intensity is higher when relatively comparing with steel with each, steel of the present invention (C-4, C-6, T-1, T-2, T-3 T-4) has kept high uniform elongation, particularly after cold working.These results can well be understood from Fig. 2, the figure shows steel of the present invention and relatively use hot-rolled steel sheet and the uniform elongation of thin plate and the relation between the intensity of steel, and in the actual production line by the uniform elongation of the resulting square tube of the above-mentioned steel plate of cold shaping and the relation between the intensity.
As mentioned above, in the present invention, even can not reduce a kind of like this degree of ordinary student productive rate and still have 34 catching a cold to be formed into to 62kgf/mm
2Tensile strength and the high tensile hot rolled steel sheet and the thin plate of extremely superior uniform elongation can have the bigger TiN particle that disperse strengthens ability to make it to form by the composition that limits in the steel, and produce mutually by forming effective perlite therein.As ordinary construction with and steel for welded structures system product and as the material of pipe and square tube, shaped steel, sheet pile etc., high tensile hot rolled steel sheet and thin plate are exceedingly useful.
Table 2
(temperature ℃)
The production technique plate slab adds final rolling temperature steel sheet volume air cooling to be risen
Hot temperature is got temperature beginning temperature
IS?A 1200 950 680 -
IS?B 1230 880 630 -
CS C 1230 790
490 -
IS D 11
0 900 - 700
Annotate: (1) TS=steel of the present invention; CS=relatively uses steel
(2) temperature is lower than transition point Ar3
Claims (8)
- High tensile hot rolled steel sheet and thin plate that 1, superior uniform elongation is arranged after cold working, contain by weight conversion and be 0.04% to 0.25% C, 0.0050% to 0.0150% N and 0.003% to 0.050% folding Ti, described steel plate and thin plate have 0.10% to 0.45% the carbon equivalent of determining by following formula (Ceq) and press the area percentage and convert, total amount is 5% to 20% perlite phase, it also contain have average particle size particle size be 1 μ m and 30 μ m and disperse therein, convert by 0.0008% to 0.015% TiN by weight:Ceq=C+Si/24+Mn/6+Ni/40+Cr/5+Mo/4+V/14。
- 2, high tensile hot rolled steel sheet according to claim 1 and thin plate is characterized by, and tensile strength is 34 to 62kgf/mm 2
- 3, high tensile hot rolled steel sheet according to claim 1 and thin plate, it is characterized by, steel plate and thin plate also contain at least a composition of choosing from following combination, this combination by conversion by weight be 0.01% to 0.7% Si, by weight conversion be 0.1% to 2.0% Mn, by weight conversion be 0.05% to 1.0% Ni, by weight conversion be 0.05% to 1.0% Cr, by weight conversion be 0.02% to 0.5% Mo and by weight conversion be that 0.005% to 0.2% V forms.
- 4, according to claim 1 or 3 described high tensile hot rolled steel sheet and thin plates, it is characterized by, also further contain at least a composition of from following combination, choosing in steel plate and the thin plate, this combination by conversion by weight be 0.05% to 1.0% Cu, by weight conversion be 0.005% to 0.05% Nb, by weight conversion be 0.001% to 0.1% Al, by weight conversion be 0.0005% to 0.0020% B, be calculated by weight to 0.0005% to 0.0070% Ca and by weight conversion be that 0.001% to 0.050% REM forms.
- 5, high tensile hot rolled steel sheet according to claim 1 and thin plate is characterized by, and will control to satisfy following condition the content of P and S:P≤0.025%, conversion by weight,S≤0.025%, conversion by weight, andP+S≤0.04%, conversion by weight.
- 6, a kind of technology of after cold working, producing high tensile hot rolled steel sheet and thin plate with superior uniform elongation, it comprise with contain by weight conversion be 0.04% to 0.25% C, by weight conversion be 0.0050% to 0.0150% N and by weight conversion be that 0.003% to 0.050% Ti and the plate slab with carbon equivalent (Ceq.) 0.10% to 0.45% are heated to 1000 to 1300 ℃, begin rolling through heating hot plate slab and be at least transition point Ar 3Temperature under carry out finish rolling, begin air cooling from the temperature that is at least 500 ℃ then.
- 7, technology according to claim 6 is characterized by, and a block plate is to produce by product is begun air cooling from the temperature that is at least 500 ℃.
- 8, technology according to claim 6 is characterized by, and band is by batching product under 500 ℃ the temperature and it is carried out air cooling produce being at least.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94102515A CN1037700C (en) | 1994-02-25 | 1994-02-25 | High strength hot rolled steel plates and sheets excellent in uniform elongation after cold working and process for producing the same |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94102515A CN1037700C (en) | 1994-02-25 | 1994-02-25 | High strength hot rolled steel plates and sheets excellent in uniform elongation after cold working and process for producing the same |
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| Publication Number | Publication Date |
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| CN1107521A true CN1107521A (en) | 1995-08-30 |
| CN1037700C CN1037700C (en) | 1998-03-11 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN94102515A Expired - Fee Related CN1037700C (en) | 1994-02-25 | 1994-02-25 | High strength hot rolled steel plates and sheets excellent in uniform elongation after cold working and process for producing the same |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100434560C (en) * | 2006-12-26 | 2008-11-19 | 宋立华 | Following steering axle for air suspension of automobile |
| CN102021493A (en) * | 2009-09-21 | 2011-04-20 | 宝山钢铁股份有限公司 | Hot rolled steel plate for precision stamping and manufacturing method thereof |
| CN105734422A (en) * | 2016-03-24 | 2016-07-06 | 攀钢集团攀枝花钢铁研究院有限公司 | Production method of hot-rolled steel strip for cold-rolled thin-walled tube |
| CN107304458A (en) * | 2016-04-21 | 2017-10-31 | 北大方正集团有限公司 | A kind of hot-rolled steel and its manufacture method, mooring cable and its manufacture method |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI290586B (en) * | 2003-09-24 | 2007-12-01 | Nippon Steel Corp | Hot rolled steel sheet and method of producing the same |
| JP4259347B2 (en) * | 2004-02-19 | 2009-04-30 | 住友金属工業株式会社 | Manufacturing method of high strength non-tempered seamless steel pipe |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02267222A (en) * | 1989-04-10 | 1990-11-01 | Nippon Steel Corp | Production of thick hot-rolled dual phase-type high tensile steel plate having low yield ratio |
-
1994
- 1994-02-25 CN CN94102515A patent/CN1037700C/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100434560C (en) * | 2006-12-26 | 2008-11-19 | 宋立华 | Following steering axle for air suspension of automobile |
| CN102021493A (en) * | 2009-09-21 | 2011-04-20 | 宝山钢铁股份有限公司 | Hot rolled steel plate for precision stamping and manufacturing method thereof |
| CN105734422A (en) * | 2016-03-24 | 2016-07-06 | 攀钢集团攀枝花钢铁研究院有限公司 | Production method of hot-rolled steel strip for cold-rolled thin-walled tube |
| CN105734422B (en) * | 2016-03-24 | 2018-06-05 | 攀钢集团攀枝花钢铁研究院有限公司 | The production method of the effective hot rolled strip of cold rolling thin-walled |
| CN107304458A (en) * | 2016-04-21 | 2017-10-31 | 北大方正集团有限公司 | A kind of hot-rolled steel and its manufacture method, mooring cable and its manufacture method |
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| CN1037700C (en) | 1998-03-11 |
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