CN101600812A - The high tensile steel of excellent in delayed fracture resistance and manufacture method thereof - Google Patents
The high tensile steel of excellent in delayed fracture resistance and manufacture method thereof Download PDFInfo
- Publication number
- CN101600812A CN101600812A CNA2008800037329A CN200880003732A CN101600812A CN 101600812 A CN101600812 A CN 101600812A CN A2008800037329 A CNA2008800037329 A CN A2008800037329A CN 200880003732 A CN200880003732 A CN 200880003732A CN 101600812 A CN101600812 A CN 101600812A
- Authority
- CN
- China
- Prior art keywords
- following
- steel
- high tensile
- temperature
- transformation temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Landscapes
- Heat Treatment Of Steel (AREA)
Abstract
The invention provides tensile strength 600MPa above, be suitable as high tensile steel and manufacture method thereof that building industry machinery such as uses at excellent in delayed fracture resistance.Particularly, a kind of steel, contain C, Si, Mn, Al, N, P, S, contain one or more elements among Mo, Nb, V, Ti, Cu, Ni, Cr, W, B, Ca, REM, the Mg as required, surplus is made of Fe and unavoidable impurities, the mean value of the length-to-diameter ratio of original austenite grain is more than 3 in whole thickness of slab direction, and perhaps the cementite fraction of coverage at lath interface further is below 50%, and perhaps delayed fracture resistance degree of safety index further is more than 75%.In addition, a kind of method of making the high tensile steel of excellent in delayed fracture resistance, wherein, after casting above-mentioned steel, be not cooled to below the Ar3 transformation temperature, perhaps, reheat is to more than the Ac3 transformation temperature, the rolling rate in the non-recrystallization district of carrying out then is the hot rolling more than 30%, then from being cooled to temperature below 350 ℃ with the speed of cooling more than 1 ℃/second more than the Ar3 transformation temperature, carries out tempering then below the Ac1 transformation temperature.
Description
Technical field
The present invention relates to good high tensile steel of delayed fracture resistance characteristics (delayed fracture resistance) (high tensile strength steels) and manufacture method thereof, and relate to tensile strength (tensile strength) 600MPa high tensile steel above, excellent in delayed fracture resistance when particularly tensile strength 900MPa is above.
Background technology
In recent years, building industry machinery (for example chassis (chassis) of the swing arm (move) of lifting machine (crane) or lifting machine), jar (tank), pressure water pipe (penstock), pipeline (pipeline) etc. use in the field of steel, the large-scale background that turns to structure (structure), in the high strength that points to used steel, severe cruelization of the environment for use of steel (use enviroment) constantly made progress.
But; severe cruelization of the high strength of known this steel and the environment for use of steel can improve the delayed fracture susceptibility of steel usually, for example the F 11T grade bolt (tensile strength 1100～1300N/mm that stipulates for JIS (Japanese Industrial Standards) B 1186 in high strength bolt (high tensile bolt) field
2), the obsolete record etc. of trying one's best limits and uses High Strength Steel.
Therefore, in Japanese kokai publication hei 3-243745 communique, TOHKEMY 2003-73737 communique, TOHKEMY 2003-239041 communique, TOHKEMY 2003-253376 communique and the TOHKEMY 2003-321743 communique etc., proposed to utilize the manufacture method of steel of the excellent in delayed fracture resistance of the fine various technology such as decentralized of the control of use, tissue morphology, the carbide of suitably change of composition, grain-boundary strengthening, crystal grain miniaturization, hydrogen trap (hydrogen trap site).
But, even utilize the method for record in above-mentioned Japanese kokai publication hei 3-243745 communique, TOHKEMY 2003-73737 communique, TOHKEMY 2003-239041 communique, TOHKEMY 2003-253376 communique and the TOHKEMY 2003-321743 communique etc., when intensity rank is high, also be difficult to obtain under severe cruel corrosive environment, use time to require other delayed fracture resistance characteristics of level, particularly high-level time more than tensile strength 900MPa requires better high tensile steel of delayed fracture resistance characteristics and manufacture method thereof.
The present invention In view of the foregoing finishes, and it is more than the 600MPa, when particularly 900MPa is above that its purpose is to provide tensile strength, high tensile steel and manufacture method thereof that delayed fracture resistance characteristics is better than existing steel.
Summary of the invention
The so-called diffustivity hydrogen (diffusible hydrogen) that can not spread in steel under the room temperature is accumulated in stress concentration portion (stress concentration zone), when its amount reaches the ultimate value (threshold limit value) of material, delayed fracture takes place, and this ultimate value depends on the strength of materials and tissue etc.
The delayed fracture of high-strength steel is a starting point with non-metallic inclusions such as MnS (non-metallicinclusion) etc. usually, how to rupture along original austenite crystal prevention (prior austenite grain boundaries) etc.
Therefore, as a policy that improves delayed fracture resistance characteristics, can enumerate the method for non-metallic inclusion amounts such as reducing MnS or raising original austenite crystal prevention intensity.
The inventor is in view of above-mentioned viewpoint, for the delayed fracture resistance characteristics that improves steel is furtherd investigate repeatedly, found that, content by reducing particularly impurity element (impurity elements) P and S and introduce elongation (extension) and deformation bands (deformation band) by the crystal grain that rolling processing produced in non-recrystallization district (non-recrystallization region), can reduce the growing amount of non-metallic inclusion MnS, and further segregate to impurity element P on the original austenite crystal prevention to the coverage density (covering density) of crystal boundary by reduction, perhaps reduce cementite (cementite) amount that precipitate into lath (lath) interface, the intensity that can suppress original austenite crystal prevention reduces, thereby can access the high tensile steel with delayed fracture resistance characteristics better than current material.
The present invention is based on above opinion, further study and finish, that is, the present invention is:
1. the high tensile steel of an excellent in delayed fracture resistance, it is characterized in that, in quality %, contain Elements C: 0.02～0.25%, Si:0.01～0.8%, Mn:0.5～2.0%, Al:0.005～0.1%, N:0.0005～0.008%, P:0.02% following, below the S:0.004%, surplus is made of Fe and unavoidable impurities, and the mean value of the length-to-diameter ratio of original austenite grain (aspectratio) is more than 3 in whole thickness of slab direction.
2. as 1 described high tensile steel, wherein, below the S:0.003%, and the cementite fraction of coverage at lath interface is below 50%.
3. as the high tensile steel of 1 or 2 described excellent in delayed fracture resistance, it is characterized in that, in quality %, steel form contain also that Mo:1% is following, Nb:0.1% is following, V:0.5% is following, Ti:0.1% is following, Cu:2% is following, Ni:4% is following, Cr:2% is following, W:2% one or more in following.
4. the high tensile steel of each described excellent in delayed fracture resistance as in 1～3, it is characterized in that, in quality %, steel form contain also that B:0.003% is following, Ca:0.01% is following, REM:0.02% is following, Mg:0.01% one or more in following.
5. the high tensile steel of each described excellent in delayed fracture resistance as in 1～4 is characterized in that, make contain hydrogen in the steel after, by zinc-plated (zinc galvanizing) hydrogen is enclosed in the steel, then, carry out strain rate (strain rate) 1 * 10
-3/ second following low strain rate tension test (slow strain rate teat), the delayed fracture resistance degree of safety index of being obtained by following formula (safetyindex of delayed fracture resistance) is more than 75%,
Delayed fracture resistance degree of safety index (%)=100 * (X
1/ X
0)
In the formula, X
0: do not contain the relative reduction in area of the test film of diffustivity hydrogen in fact, X
1: the relative reduction in area that contains the test film of diffustivity hydrogen.
6. as 5 described high tensile steels, wherein, described delayed fracture resistance degree of safety index is more than 80%.
7. the manufacture method of the high tensile steel of above-mentioned 5 described excellent in delayed fracture resistance is characterized in that, after casting has the steel of each described composition in 1～4, is not cooled to Ar
3Below the transformation temperature (transformation temperature), perhaps, reheat is to Ac
3More than the transformation temperature, beginning hot rolling then, is the thickness of slab that regulation is made in rolling hot rolling (hot rolling) more than 30% by the rolling rate (rolling reduction) in the non-recrystallization district of being included in, then from Ar
3Transformation temperature is above to be cooled to the temperature below 350 ℃ with the speed of cooling more than 1 ℃/second (cooling rate), then at Ac
1Carry out tempering below the transformation temperature.
8. the manufacture method of the high tensile steel of above-mentioned 6 described excellent in delayed fracture resistance is characterized in that, at above-mentioned 7 described Ac
1In the tempering method below the transformation temperature, use and roller mill and refrigerating unit are arranged on the heating unit on the same production line, set from 370 ℃ to Ac
1The average heating speed of the thickness of slab central part of the regulation tempering temperature that transformation temperature is following is more than 1 ℃/second, and carrying out tempering and making the Da Wendu that is up to of thickness of slab central part is more than 400 ℃.
9. the manufacture method of the high tensile steel of above-mentioned 6 described excellent in delayed fracture resistance is characterized in that, at above-mentioned 8 described Ac
1In the following tempering method of transformation temperature, further setting the average heating speed that begins the thickness of slab central part of temperature to 370 ℃ from tempering is more than 2 ℃/second.
According to the present invention, can make the extremely good high tensile steel of delayed fracture resistance characteristics more than the tensile strength 600MPa, when particularly 900MPa is above, industrial very useful.
Description of drawings
Fig. 1 is the synoptic diagram of expression martensitic stucture of the present invention.
Fig. 2 precipitate into synoptic diagram and transmission electron microscope (transmission electronmicroscope, TEM) (extraction replica (extracted replica)) photo of the cementite at lath interface when representing low speed heating tempering of the present invention and rapid heating tempering.
Embodiment
(one-tenth is grouped into)
Qualification reason to composition among the present invention describes." % " that the expression chemical ingredients is formed is quality %.
C：0.02～0.25％
C contains in order to ensure intensity, and is insufficient less than 0.02% o'clock this effect, on the other hand, surpasses the toughness variation of 0.25% o'clock mother metal and welding heat affected zone, simultaneously the remarkable variation of weldability.Therefore, C content is defined as 0.02～0.25%.Further preferred 0.05～0.20%.
Si：0.01～0.8％
Si is as the deoxidation material in system steel stage and improve the element of intensity and contain, and is insufficient less than 0.01% o'clock this effect, on the other hand, surpasses 0.8% o'clock embrittlement of grain boundaries, promotes the generation of delayed fracture.Therefore, Si content is defined as 0.01～0.8%.Further preferred 0.1～0.5%.
Mn：0.5～2.0％
Containing Mn is in order to ensure intensity, and enrichment in cementite during owing to tempering, diffusion as the Mn of substitutional atom can limit the speed that cementite is grown up, thereby thickization that suppresses cementite, but it is insufficient less than 0.5% o'clock this effect, on the other hand, surpass the toughness variation of 2.0% o'clock welding heat affected zone, simultaneously the remarkable variation of weldability.Therefore, Mn content is defined as 0.5～2.0%.Further preferred 0.7～1.8%.
Al：0.005～0.1％
Al adds as deoxidation material, also has the effect that makes the miniaturization of crystallization particle diameter simultaneously, and is insufficient less than 0.005% o'clock this effect, on the other hand, surpasses 0.1% o'clock steel plate and is easy to generate surface imperfection.Therefore, Al content is defined as 0.005～0.1%.Further preferred 0.01～0.05%.
N：0.0005～0.008％
N organizes miniaturization by making with formation nitride such as Ti, adds in order to have the flexible effect that improves mother metal and welding heat affected zone.Micronized effect less than 0.0005% o'clock tissue is insufficient, and on the other hand, adding above 0.008% o'clock solid solution N amount increases, thereby the toughness of mother metal and welding heat affected zone is impaired.Therefore, N content is defined as 0.0005%～0.008%.Further preferred 0.001%～0.005%.
Below the P:0.02%
Segregate to crystal boundaries such as original austenite crystal prevention when the temper easily as the P of impurity element, surpassing the bonding strength that made adjacent crystal grain at 0.02% o'clock reduces, low-temperature flexibility and delayed fracture resistance characteristics variation.Therefore, P content is defined as below 0.02%.Further preferred below 0.015%.
Below the S:0.004%
S as impurity element generates non-metallic inclusion MnS easily, and the amount that surpasses 0.004% o'clock inclusion is too much, and delayed fracture strength reduces, low-temperature flexibility and delayed fracture resistance characteristics variation.Therefore, S content is defined as below 0.004%.Further preferred below 0.003%.
Among the present invention, can further contain following composition according to needed characteristic.
Below the Mo:1%
Mo has the effect that improves hardening capacity and intensity, simultaneously, catches diffustivity hydrogen by forming carbide, and delayed fracture resistance characteristics is improved.In order to obtain this effect, preferably add more than 0.05%.But, then less economical above 1% interpolation.Therefore, when adding Mo, its content is defined as below 1%.Further preferred below 0.8%.But, Mo has the effect that increases the temper softening opposing,, preferably adds more than 0.2% more than 900MPa in order to ensure intensity.
Below the Nb:0.1%
Nb improves intensity as microalloy element, simultaneously, catches diffustivity hydrogen by forming carbide, nitride or carbonitride, and delayed fracture resistance characteristics is improved.In order to obtain this effect, preferably add more than 0.01%.But the interpolation above 0.1% can make the toughness variation of welding heat affected zone.Therefore, when adding Nb, its content is defined as below 0.1%.Further preferred below 0.05%.
Below the V:0.5%
V improves intensity as microalloy element, simultaneously, catches diffustivity hydrogen by forming carbide, nitride or carbonitride, and delayed fracture resistance characteristics is improved.In order to obtain this effect, preferably add more than 0.02%.But the interpolation above 0.5% can make the toughness variation of welding heat affected zone.Therefore, when adding V, its content is defined as below 0.5%.Further preferred below 0.1%.
Below the Ti:0.1%
Ti generates TiN when rolling heating or welding, suppress the growth of austenite crystal, improves the toughness of mother metal and welding heat affected zone, simultaneously, catches diffustivity hydrogen by forming carbide, nitride or carbonitride, and delayed fracture resistance characteristics is improved.In order to obtain this effect, preferably add more than 0.005%.But the interpolation above 0.1% can make the toughness variation of welding heat affected zone.Therefore, when adding Ti, its content is defined as below 0.1%.Further preferred below 0.05%.
Below the Cu:2%
Cu has the effect that improves intensity by solution strengthening and precipitation strength.In order to obtain this effect, preferably add more than 0.05%.But Cu content surpasses at 2% o'clock, is easy to generate thermal crack during the steel disc heating or during welding.Therefore, when adding Cu, its content is defined as below 2%.Further preferred below 1.5%.
Below the Ni:4%
Ni has the effect that improves toughness and hardening capacity.In order to obtain this effect, preferably add more than 0.3%.But Ni content is less economical above 4% o'clock.Therefore, when adding Ni, its content is defined as below 4%.Further preferred below 3.8%.
Below the Cr:2%
Cr has the intensity of raising and flexible effect, and the hot strength characteristic good.And, because enrichment in cementite during tempering, can limit the speed that cementite is grown up as the diffusion of the Cr of substitutional atom, also have the effect that suppresses thickization of cementite.Therefore, preferably when high strength and thickization of inhibition cementite, initiatively add, particularly, preferably add more than 0.3% in order to obtain the characteristic more than the tensile strength 900MPa.But Cr content surpasses 2% o'clock weldability variation.Its content is defined as below 2% when therefore, adding Cr.Further preferred below 1.5%.
W：2％
W has the effect that improves intensity.In order to obtain this effect, preferably add more than 0.05%.But, surpass 2% o'clock weldability variation.Therefore, when adding W, its content is defined as below 2%.
Below the B:0.003%
B has the effect that improves hardening capacity.In order to obtain this effect, preferably add more than 0.0003%.But, surpass 0.003% o'clock toughness variation.Therefore, when adding B, its content is defined as below 0.003%.
Below the Ca:0.01%
Ca is for the indispensable element of the morphology Control of sulfide-based inclusion.In order to obtain this effect, preferably add more than 0.0004%.But, add above 0.01% o'clock, cause cleanliness factor and delayed fracture resistance characteristics to reduce.Therefore, when adding Ca, its content is defined as below 0.01%.
Below the REM:0.02%
(annotate: REM is the abbreviation of Rare Earth Metal to REM, be rare earth metal) generate the solid solution S amount that REM oxysulfide (oxysulside) reduces crystal boundary by form in steel with REM (rare-earth metal) (O, S), (proof stress is eliminated crackle to improve the crackle of anti-SR characteristic, stressrelief cracking resistance) (perhaps also claims the crackle of anti-PWHT characteristic (anti-postweld heat treatment, post welded heat treatment cracking resistance)).In order to obtain this effect, preferably add more than 0.001%.But, adding above 0.02% o'clock, the REM oxysulfide is significantly accumulated in the precipitation crystalline region, causes the deterioration of material.Therefore, when adding REM, its addition is defined as below 0.02%.
Below the Mg:0.01%
Mg uses as the desulfurizing iron material sometimes.In order to obtain this effect, preferably add more than 0.001%.But interpolation surpasses at 0.01% o'clock and causes cleanliness factor to reduce.Therefore, when adding Mg, its addition is defined as below 0.01%.
[microstructure]
Qualification reason to microstructure among the present invention describes.
The representativeness that constitutes high-strength steel of the present invention is organized as martensite or bainite.Martensitic stucture particularly of the present invention has and organizes a plurality of distinctive 4 kinds of organization unit shown in the synoptic diagram (original austenite grain (prior austenite), lath bundle (packet), lath block (block), lath (lath)) the fine and complicated form of layering eclipsed as Fig. 1.At this, the lath bundle is defined as the zone that is formed by the lath colony with the identical habit plane (habit plane) that is arranged in parallel, and lath block is by parallel and be orientated identical lath colony and constitute.
Among the present invention, the mean value of the length-to-diameter ratio of original austenite grain (the ratio a/b of the major axis a of original austenite grain and minor axis b among Fig. 1) is more than 3, to be preferably more than 4 in whole thickness of slab direction.
Be set at more than 3 by length-to-diameter ratio original austenite grain, segregate to the crystal boundary fraction of coverage of the P on original austenite crystal prevention, lath bundle border etc. when reducing temper, improve low-temperature flexibility (low-temperature toughness) and delayed fracture resistance characteristics, make this microstructure (microstructure) be present in whole thickness of slab direction, obtain possessing the homogeneous steel of above-mentioned characteristic thus.
The mensuration of the length-to-diameter ratio of original austenite grain, after for example using picric acid (picric acid) that original austenite grain is showed, (image analysis) estimates by image analysis, with the simple average value of the length-to-diameter ratio of for example 500 the above original austenite grains length-to-diameter ratio as original austenite grain.
Among the present invention, the mean value of length-to-diameter ratio is to be meant more than 3 in whole thickness of slab direction, at least under the surface of surface of steel plate under the surface at 1mm, 1/4,1/2,3/4 one of thickness of slab, the steel plate back side mean value of the length-to-diameter ratio at each position of 1mm be more than 3, further preferred situation more than 4.
The inventor has further carried out detailed research on the basis of the above, found that, be below 50% particularly by the carburizing scale of construction of separating out on a large amount of fine lath interface that generates in the lath block that makes Fig. 1 (hereinafter referred to as the cementite fraction of coverage at lath interface), the intensity that can suppress original austenite crystal prevention reduces, and improves delayed fracture resistance characteristics.The cementite fraction of coverage at lath interface is more preferably below 30%.Fig. 2 represents the synoptic diagram and the TEM photo of the cementite of separating out on the lath interface.
As shown in Figure 2, the cementite fraction of coverage at lath interface is to utilize scanning electron microscope to the tissue that shows is taken pictures with nital (nital), uses this photo, for example measures 50 with the cementite of separating out on the top bars interface length (L along the interface
Cementite) and the length (L at lath interface
Lath), will with cementite along the summation of the length at lath interface divided by the summation of the length at lath interface multiply by again 100 and the numerical value that obtains as the cementite fraction of coverage at lath interface.
[delayed fracture resistance degree of safety index]
Among the present invention, can further stipulate: make contain hydrogen in the steel after, by zinc-plated hydrogen is enclosed in the steel, then, carry out strain rate 1 * 10
-3/ second following low strain rate tension test, the delayed fracture resistance degree of safety index of being obtained by following formula is more than 75%, more preferably more than 80%.
Delayed fracture resistance degree of safety index (%)=100 * (X
1/ X
0)
In the formula, X
0: do not contain the relative reduction in area of the test film of diffustivity hydrogen in fact, X
1: the relative reduction in area that contains the test film of diffustivity hydrogen
According to delayed fracture resistance degree of safety index, can estimate the quality of the delayed fracture resistance characteristics of steel quantitatively, this index is high more, we can say that delayed fracture resistance characteristics is good more, but when under common atmospheric environment, using steel, by delayed fracture resistance degree of safety index is set at more than 75%, further preferred more than 80%, can access the practical fully good delayed fracture resistance characteristics of going up.But, for the steel grade of tensile strength less than 1200MPa, owing to use under severe cruel environment such as corrosive environment or low temperature environment sometimes, perhaps degree of finish is violent sometimes, therefore preferably has 80% or more, further preferred delayed fracture resistance degree of safety index more than 85%.
[creating conditions]
The present invention can be applied to the steel of steel plate (steel plate), shaped steel (steel shapes) and bar steel different shapes such as (steelbar), temperature in creating conditions is defined as the temperature regulation of steel central part, steel plate is the thickness of slab center, shaped steel is the thickness of slab center of giving the position of characteristic of the present invention, and rod iron is diametric center.But, also have temperature history much at one near the central part, therefore be not limited to center itself.
Casting condition (cast condition)
The steel that the present invention makes down for any casting condition are all effective, therefore need not to limit especially casting condition.The method of making steel billet by the method and the rolling cast slab of molten steel manufacturing cast slab is not particularly limited.Can utilize by steel after the meltings such as converter process, electric furnace process or the steel billet made by continuous casting, ingot casting method etc.
Hot-rolled condition
Rolling cast slab and when making steel billet, can not be cooled to Ar
3Directly begin hot rolling below the transformation temperature, also can be with temporary transient refrigerative cast slab reheat to Ac
3Begin hot rolling after transformation temperature is above.This is because as long as beginning is rolling in this temperature range, just can not lose validity of the present invention.
In addition, the rolling rate in the non-recrystallization district is set at more than 30%, is preferably set to more than 40%, and at Ac
3The above end of transformation temperature is rolling.This is because the non-recrystallization district of rolling rate 30% or more is rolling, and austenite crystal is elongated, and introduces deformation bands simultaneously, thereby segregates to the crystal boundary fraction of coverage reduction of the P of crystal boundary when making temper.
The length-to-diameter ratio of original austenite grain is high more, then effectively the crystallization particle diameter (forms the particle diameter (effective grain size) of the unitary crystal grain of section, particularly be the lath bundle) miniaturization more, and the crystal boundary fraction of coverage on the original austenite crystal prevention of P, lath bundle border etc. is more little, so delayed fracture resistance characteristics improves.
Among the present invention, ask Ar
3Transformation temperature (℃) and Ac
3Transformation temperature (℃) formula be not particularly limited, can adopt for example Ar
3=910-310C-80Mn-20Cu-15Cr-55Ni-80Mo, Ac
3=854-180C+44Si-14Mn-17.8Ni-1.7Cr.Each element adopts content (quality %) in the steel in these formulas).
Cooling conditions after the hot rolling
After hot rolling finishes, in order to ensure strength of parent and base metal tenacity, from Ar
3Temperature below the above temperature to 350 of transformation temperature ℃ is forced cooling with the speed of cooling more than 1 ℃/second.Force cooling beginning temperature to be set at Ar
3The above reason of transformation temperature is for steel plate is begun to cool down from the state of austenite one phase.When from being lower than Ar
3When the temperature range of transformation temperature began to cool down, it is inhomogeneous that quenching structure becomes, and causes toughness and delayed fracture resistance characteristics variation.It is in order to finish from the austenite to martensite or the phase transformation of bainite that steel billet temperature is cooled to reason below 350 ℃, thereby makes the mother metal highly malleablized and improve delayed fracture resistance characteristics.The speed of cooling of this moment is set at more than 1 ℃/second, preferred more than 2 ℃/second.In addition, speed of cooling is to finish the back from Ar with hot rolling
3The above temperature of transformation temperature is cooled to the average cooling rate that the needed temperature head of temperature below 350 ℃ obtains divided by this cooling required time.
Tempered condition
The Da Wendu that is up at the thickness of slab central part is Ac
1Carry out temper under the specified temperature below the transformation temperature.Be defined as Ac
1The following reason of transformation temperature is because surpass Ac
1Produce austenite phase transformation during transformation temperature, intensity significantly reduces.In addition, preferably use and roller mill and refrigerating unit are arranged on the same production line and are arranged at the online heating unit in refrigerating unit downstream side in tempering.Its reason is, can shorten from rolling, quench treatment to the required time of temper, thereby boost productivity.
In addition, the heat-up rate during tempering is preferably more than 0.05 ℃/second.During less than 0.05 ℃/second, the amount that P segregates on original austenite crystal prevention, the lath bundle border etc. during temper increases low-temperature flexibility and delayed fracture resistance characteristics variation.In addition, if the heat-up rate during tempering is the low speed heating below 2 ℃/second, then consider that from the growth that suppresses precipitates such as cementite and the viewpoint of productivity the hold-time of tempering temperature was preferably set to below 30 minutes.
In addition, with from 370 ℃ to Ac
1The average heating speed of the thickness of slab central part of the regulation tempering temperature that transformation temperature is following is that the rapid heating more than 1 ℃/second is preferred tempered condition, and preferably carrying out tempering and make the Da Wendu that is up to of thickness of slab central part is more than 400 ℃.
The reason that average heating speed is set at more than 1 ℃/second is the crystal boundary fraction of coverage that segregates to the impurity element P on original austenite crystal prevention, the lath bundle border etc. in order to reduce, and shown in the comparison of the synoptic diagram of the cementite of separating out on the lath interface when low speed of the present invention heating tempering and rapid heating tempering among Fig. 2 and TEM photo, realize the reduction of the carburizing scale of construction separated out on the lath interface.
More effectively preventing the P grain boundary segregation under the situation on original austenite crystal prevention, lath bundle border etc., above-mentioned from 370 ℃ to Ac
1The average heating speed of the thickness of slab central part of the regulation tempering temperature that transformation temperature is following is on the basis of the rapid heating more than 1 ℃/second, and further the average heating speed that preferably begins the thickness of slab central part of temperature to 370 ℃ from tempering is the rapid heating more than 2 ℃/second.
The average heating speed that setting begins the thickness of slab central part of temperature to 370 ℃ from tempering is that the reason more than 2 ℃/second is because P segregates in this temperature range on original austenite crystal prevention, the lath bundle border etc. especially easily.
In addition, setting from 370 ℃ to Ac
1The average heating speed of the thickness of slab central part of the regulation tempering temperature that transformation temperature is following is more than 1 ℃/second, and further to set the average heating speed that begins the thickness of slab central part of temperature to 370 ℃ from tempering be more than 2 ℃/second the time, in order to boost productivity and to prevent the delayed fracture resistance characteristics variation that thickization of precipitates such as cementite causes, the hold-time of tempering temperature was preferably set to below 60 seconds.In addition, heat-up rate is to be up to the Da Wendu reheat to Ac with cooling back thickness of slab central part
1The average heating speed that the following needed temperature head of specified temperature of transformation temperature obtains divided by the reheat required time.
For thickization of precipitate in preventing to cool off, the speed of cooling after the tempering preferably is set at the average cooling rate of tempering temperature～200 ℃ more than 0.05 ℃/second.
In addition, be used for the tempered heating and can be induction heating (induction heating), energising heating (energization heating), infrared radiation heating (infra-red radiant heating), gas heating any modes such as (furnace heating).
Tempering unit can use be arranged on heating unit on the different production lines with roller mill and direct quenching device, also can use directly is connected with roller mill and direct quenching device and is arranged on heating unit on the same production line.The heating unit of any configuration does not all influence effect of the present invention.
Embodiment 1
Table 1 and 2 shows the chemical ingredients of the steel that uses among the embodiment, and table 3 and 4 shows that steel plate is created conditions, the length-to-diameter ratio of original austenite grain.
Steel A～Z, the AA～II of chemical ingredients shown in the his-and-hers watches 1 and 2 carry out melting, be cast as steel billet (billet bloom size: high 100mm * wide 150mm * long 150mm), after in process furnace, being heated to the Heating temperature shown in table 3 and 4, rolling rate with the non-recrystallization district shown in table 3 and 4 is carried out hot rolling, makes steel plate.After the hot rolling, then beginning temperature, direct quenching final temperature and speed of cooling with the direct quenching shown in table 3 and 4 carries out direct quenching, then, use electromagnetic type induction heating device (solenoid type induction heating apparatus) to begin temperature, tempering temperature and hold-time and carry out temper with the tempering shown in table 3 and 4.Direct quenching (directquenching) is by forcing cooling (water-cooled) to be carried out to the temperature below 350 ℃ with the speed of cooling more than 1 ℃/second.
In addition, the average heating speed of thickness of slab central part is controlled by the plate speed of steel plate.In addition, remain under the situation of tempering temperature, heat, remain in the scope with respect to target Heating temperature ± 5 ℃ by steel plate is come and gone in the electromagnetic type induction heating device.
In addition, air cooling (air cooling) is adopted in the cooling after the tempering heating as shown in Tables 3 and 4.The temperature of thickness of slab such as tempering temperature, quenching temperature central part is by the temperature measuring result who uses radiation pyrometer (emissionpyrometer) in surperficial sequential test, and (heat transfercalculation) obtains by Calculation of Heat Transfer.
The yield strength (yield strength), tensile strength, ductile-brittle transition temperature (fracture appearance transition temperature) that table 5 and 6 shows the gained steel plates (vTrs), delayed fracture resistance degree of safety index.
Speed of cooling is for to begin the average cooling rate of temperature to the thickness of slab central part the direct quenching final temperature from direct quenching.
The test film that uses in the following test is respectively to gather 3 test films in 1/4 position of the central part of steel plate length direction and steel plate width direction.
The length-to-diameter ratio of original austenite grain is to use opticmicroscope (optical microscopy) at each position of 1mm under the surface at 1mm, 1/4,1/2,3/4 one of thickness of slab, the steel plate back side under the surface of surface of steel plate the tissue after corroding (etching) with picric acid to be taken pictures, each measures the length-to-diameter ratio of about 500 original austenite grains, obtains its mean value.
In addition, yield strength and tensile strength utilize total thickness tension test sheet to measure according to JIS Z2241, and toughness is used from the test film of thickness of slab central part collection according to JIS Z2242 and carried out pendulum impact test, estimates by the vTrs that obtains thus.
In addition, delayed fracture resistance degree of safety index uses bar-shaped test film, (cathodic hydrogen charging) fills hydrogen by the cathodic hydrogen charging method, make the diffustivity hydrogen amount (amount ofdiffusible hydrogen) in the test film reach about 0.5 quality ppm, carry out zinc-plated to the test film surface then, enclose hydrogen thus, then with 1 * 10
-6The strain rate of/second is carried out tension test, obtains the relative reduction in area (reduction of area) of the test film of fracture, with same strain rate the test film that does not fill hydrogen is carried out tension test again, estimates according to following formula.
Delayed fracture resistance degree of safety index (%)=100 * (X
1/ X
0)
In the formula, X
0: do not contain the relative reduction in area of the test film of diffustivity hydrogen in fact, X
1: the relative reduction in area that contains the test film of diffustivity hydrogen.
The target of vTrs is below-40 ℃ for tensile strength less than the steel grade of 1200MPa, is below-30 ℃ for the steel grade more than the tensile strength 1200MPa.On the other hand, delayed fracture resistance degree of safety exponential target is more than 80% for tensile strength less than the steel grade of 1200MPa, is more than 75% for the steel grade more than the tensile strength 1200MPa.
Table 3 and 4 shows, steel plate No.18～20 of the rolling rate in non-recrystallization district outside the scope of the invention, and the length-to-diameter ratio of its original austenite grain is also outside the scope of the invention.
In addition, table 5 and 6 shows, by steel plate No.1～17 and steel plate No.33～39 (example of the present invention) that the inventive method is made, the length-to-diameter ratio of its chemical ingredients, manufacture method, original austenite grain can access good vTrs and delayed fracture resistance degree of safety index within the scope of the present invention.
Relative therewith, compare steel plate No.18～32 and steel plate No.40～44 (comparative example), at least one in its vTrs and the delayed fracture resistance degree of safety index is outside above-mentioned target zone.Below, these comparative examples are described respectively.
Steel plate No.29～32 and steel plate No.40～44 of composition outside the scope of the invention, at least one the miss the mark value in its vTrs and the delayed fracture resistance degree of safety index.
Steel plate No.18～20 of the rolling rate in non-recrystallization district outside the scope of the invention, its delayed fracture resistance degree of safety index miss the mark value.
Direct quenching begins steel plate No.21～23 of temperature outside the scope of the invention, the equal miss the mark value of its vTrs and delayed fracture resistance degree of safety index.
The steel plate No.24 of direct quenching final temperature outside the scope of the invention, the equal miss the mark value of its vTrs and delayed fracture resistance degree of safety index.
Speed of cooling and the direct quenching final temperature steel plate No.25 outside the scope of the invention, the equal miss the mark value of its vTrs and delayed fracture resistance degree of safety index.
Steel plate No.26～28 of tempering temperature outside the scope of the invention, the equal miss the mark value of its vTrs and delayed fracture resistance degree of safety index.
Embodiment 2
Steel A～Z, the AA～II of chemical ingredients shown in the his-and-hers watches 7 and 8 carry out melting, are cast as steel billet under creating conditions similarly to Example 1, after the heating, carry out hot rolling in process furnace, make steel plate.After the hot rolling, then carry out direct quenching, then, use the electromagnetic type induction heating device to carry out tempering.Direct quenching is by forcing cooling (water-cooled) to be carried out to the temperature below 350 ℃ with the speed of cooling more than 1 ℃/second.
The length-to-diameter ratio of original austenite grain is obtained similarly to Example 1, adopts the mean value of the length-to-diameter ratio of about 550 original austenite grains.
The cementite fraction of coverage at lath interface is to use cementite that scanning electron microscope separates out on about 60 lath interfaces taking pictures with the tissue after the nital corrosion, measuring in the thickness of slab 1/4 position length (L along the interface
Cementite) and the length (L at lath interface
Lath), will with cementite along the summation of the length at lath interface divided by the summation of the length at lath interface multiply by again 100 and the numerical value that obtains as the cementite fraction of coverage at lath interface.
In addition, yield strength, tensile strength and delayed fracture resistance degree of safety index are obtained similarly to Example 1.
The target of vTrs is below-40 ℃ for tensile strength less than the steel grade of 1200MPa, is below-30 ℃ for the steel grade more than the tensile strength 1200MPa.On the other hand, delayed fracture resistance degree of safety exponential target is more than 85% for tensile strength less than the steel grade of 1200MPa, is more than 80% for the steel grade more than the tensile strength 1200MPa.
Table 9 and 10 shows that steel plates are created conditions, the length-to-diameter ratio of original austenite grain, the cementite fraction of coverage of lath, and table 11 and 12 shows yield strength, tensile strength, ductile-brittle transition temperature (vTrs), the delayed fracture resistance degree of safety index of gained steel plates.
In addition, the division of table 9～12 illustrated embodiments is to satisfy the embodiment of condition of technical scheme 8 described inventions as example of the present invention, with as a comparative example ungratified.No.1～17 and 41～47th, the rate of heating that begins temperature to 370 ℃ from tempering is set at the embodiment more than 2 ℃/second, is technical scheme 9 described examples.
No.35,36 does not satisfy in the condition of technical scheme 9 described inventions the rate of heating that begins temperature to 370 ℃ from tempering and is set at condition more than 2 ℃/second, but satisfies the condition of technical scheme 8 described inventions, therefore is divided into example of the present invention.
Table 9 and 10 shows, steel plate No.18～20 of the rolling rate in non-recrystallization district outside the scope of the invention, and the cementite fraction of coverage of the length-to-diameter ratio of its original austenite grain and lath is all outside the scope of the invention.
In addition, steel plate No.26～28 of tempering temperature outside the scope of the invention, the cementite fraction of coverage of its lath is all outside the scope of the invention.
In addition, begin at least one steel plate No.30,32～34 outside the scope of the invention the average heating speed of the average heating speed of thickness of slab central part of temperature to 370 ℃ and the thickness of slab central part from 370 ℃ to tempering temperature from tempering, the cementite fraction of coverage of its lath is outside the scope of the invention.
In addition, table 11 and 12 shows, steel plate No.1～17 and steel plate No.35,36 (example of the present invention) by the inventive method manufacturing, the cementite fraction of coverage of the length-to-diameter ratio of its chemical ingredients, manufacture method, original austenite grain, lath can access good vTrs and delayed fracture resistance degree of safety index within the scope of the present invention.
In addition, with within the scope of the present invention, only tempering begin the different steel plate No.4 of the average heating speed of thickness of slab central part of temperature～370 ℃ and steel plate No.35 and steel plate No.12 and steel plate No.36 when comparing as can be known, the average heating speed that tempering begins the thickness of slab central part of temperature～370 ℃ is that the steel plate No.4,12 more than 2 ℃/second has respectively than steel plate No.35,36 good vTrs and delayed fracture resistance degree of safety indexes.
Relative therewith, compare steel plate No.18～34 and 37～40,48～52 (comparative examples), at least one in its vTrs and the delayed fracture resistance degree of safety index is outside above-mentioned target zone.Below, these comparative examples are described respectively.
Steel plate No.37～40 and 48～52 of composition outside the scope of the invention, the equal miss the mark value of its vTrs and delayed fracture resistance degree of safety index.
Steel plate No.18～20 of the rolling rate in non-recrystallization district outside the scope of the invention, its delayed fracture resistance degree of safety index miss the mark value.
Direct quenching begins steel plate No.21～23 of temperature outside the scope of the invention, at least one the miss the mark value in its vTrs and the delayed fracture resistance degree of safety index.
The steel plate No.24,25 of direct quenching final temperature outside the scope of the invention, its vTrs miss the mark value.
Steel plate No.26～28 of tempering temperature outside the scope of the invention, at least one the miss the mark value in its vTrs and the anti-hydrogen embrittlement degree of safety index.
Steel plate No.29～34 of the average heating speed of the thickness of slab central part of 370 ℃～tempering temperature outside the scope of the invention, at least one the miss the mark value in its vTrs and the anti-hydrogen embrittlement degree of safety index.
Utilize possibility on the industry
According to the present invention, can make tensile strength extremely good high tensile steel of delayed fracture resistance characteristics more than 600MPa, when particularly 900MPa is above, very useful on industry.
Table 5
| No. | Steel grade | Thickness of slab (mm) | Yield strength (MPa) | Tensile strength (MPa) | Thickness of slab central part vTrs (℃) | Delayed fracture resistance degree of safety index (%) | Remarks |
| 1 | A | 25 | 573 | 648 | -105 | 93 | Example of the present invention |
| 2 | B | 12 | 601 | 678 | -116 | 89 | Example of the present invention |
| 3 | C | 25 | 801 | 868 | -78 | 91 | Example of the present invention |
| 4 | D | 12 | 1023 | 1048 | -68 | 89 | Example of the present invention |
| 5 | E | 25 | 1006 | 1027 | -69 | 85 | Example of the present invention |
| 6 | F | 12 | 1056 | 1061 | -59 | 83 | Example of the present invention |
| 7 | G | 25 | 1013 | 1052 | -59 | 85 | Example of the present invention |
| 8 | H | 50 | 1014 | 1019 | -52 | 84 | Example of the present invention |
| 9 | I | 12 | 1083 | 1197 | -42 | 81 | Example of the present invention |
| 10 | J | 25 | 1197 | 1247 | -42 | 85 | Example of the present invention |
| 11 | K | 50 | 1232 | 1267 | -41 | 79 | Example of the present invention |
| 12 | L | 60 | 1017 | 1057 | -48 | 86 | Example of the present invention |
| 13 | M | 6 | 1257 | 1263 | -49 | 80 | Example of the present invention |
| 14 | N | 12 | 1357 | 1376 | -41 | 79 | Example of the present invention |
| 15 | O | 25 | 1327 | 1387 | -39 | 78 | Example of the present invention |
| 16 | P | 60 | 1287 | 1298 | -36 | 79 | Example of the present invention |
| 17 | Q | 6 | 1356 | 1387 | -35 | 78 | Example of the present invention |
| 18 | A | 25 | 476 | 553 | -42 | 46 * | Comparative example |
| 19 | B | 12 | 529 | 607 | -58 | 42 * | Comparative example |
| 20 | C | 25 | 815 | 823 | -59 | 38 * | Comparative example |
| 21 | D | 12 | 831 | 867 | -29 * | 66 * | Comparative example |
| 22 | E | 25 | 923 | 941 | -31 * | 59 * | Comparative example |
Annotate 1:
*Label table is shown in outside the scope of the invention
Annotate 2: the scope of the invention 1. thickness of slab central part vTrs (℃) tensile strength is less than below 1200MPa-40 ℃
Tensile strength 1200MPa is above below-30 ℃
2. delayed fracture resistance degree of safety index tensile strength is less than 1200MPa more than 80%
Tensile strength 1200MPa is above more than 75%
Table 6
| No. | Steel grade | Thickness of slab (mm) | Yield strength (MPa) | Tensile strength (MPa) | Thickness of slab central part vTrs (℃) | Delayed fracture resistance degree of safety index (%) | Remarks |
| 23 | F | 12 | 982 | 991 | -38 * | 52 * | Comparative example |
| 24 | G | 25 | 923 | 956 | -31 * | 78 * | Comparative example |
| 25 | H | 50 | 937 | 952 | -27 * | 76 * | Comparative example |
| 26 | I | 12 | 983 | 1063 | -27 * | 68 * | Comparative example |
| 27 | J | 25 | 1101 | 1157 | -29 * | 62 * | Comparative example |
| 28 | K | 50 | 1127 | 1151 | -27 * | 53 * | Comparative example |
| 29 | R * | 35 | 1017 | 1041 | -31 * | 43 * | Comparative example |
| 30 | S * | 50 | 1007 | 1047 | -27 * | 42 * | Comparative example |
| 31 | T * | 50 | 1009 | 1012 | -23 * | 36 * | Comparative example |
| 32 | U * | 60 | 1021 | 1061 | -15 * | 39 * | Comparative example |
| 33 | X | 25 | 562 | 627 | -102 | 96 | Example of the present invention |
| 34 | Y | 6 | 1380 | 1457 | -42 | 78 | Example of the present invention |
| 35 | Z | 25 | 1421 | 1512 | -46 | 77 | Example of the present invention |
| 36 | AA | 12 | 1358 | 1583 | -48 | 80 | Example of the present invention |
| 37 | BB | 32 | 1391 | 1623 | -42 | 79 | Example of the present invention |
| 38 | CC | 20 | 1413 | 1678 | -43 | 81 | Example of the present invention |
| 39 | DD | 32 | 1071 | 1112 | -63 | 88 | Example of the present invention |
| 40 | EE * | 16 | 1378 | 1563 | -26 * | 56 * | Comparative example |
| 41 | FF * | 8 | 1341 | 1532 | -25 * | 63 * | Comparative example |
| 42 | GG * | 12 | 1328 | 1419 | -23 * | 65 * | Comparative example |
| 43 | HH * | 12 | 1151 | 1238 | -41 | 68 * | Comparative example |
| 44 | II * | 12 | 1168 | 1241 | -28 * | 53 * | Comparative example |
Annotate 1:
*Label table is shown in outside the scope of the invention
Annotate 2: the scope of the invention 1. thickness of slab central part vTrs (℃) tensile strength is less than below 1200MPa-40 ℃
Tensile strength 1200MPa is above below-30 ℃
2. delayed fracture resistance degree of safety index tensile strength is less than 1200MPa more than 80%
Tensile strength 1200MPa is above more than 75%
Table 11
| No. | Steel grade | Thickness of slab (mm) | Yield strength (MPa) | Tensile strength (MPa) | Thickness of slab central part vTrs (℃) | Delayed fracture resistance degree of safety index (%) | Divide |
| 1 | A | 25 | 596 | 667 | -121 | 100 | Example of the present invention |
| 2 | B | 12 | 611 | 695 | -131 | 99 | Example of the present invention |
| 3 | C | 25 | 812 | 888 | -93 | 100 | Example of the present invention |
| 4 | D | 12 | 1037 | 1061 | -81 | 98 | Example of the present invention |
| 5 | E | 25 | 1015 | 1041 | -83 | 99 | Example of the present invention |
| 6 | F | 12 | 1112 | 1115 | -73 | 97 | Example of the present invention |
| 7 | G | 25 | 1069 | 1100 | -76 | 97 | Example of the present invention |
| 8 | H | 50 | 1025 | 1034 | -63 | 96 | Example of the present invention |
| 9 | I | 12 | 1151 | 1253 | -53 | 95 | Example of the present invention |
| 10 | J | 25 | 1251 | 1314 | -51 | 90 | Example of the present invention |
| 11 | K | 50 | 1296 | 1312 | -49 | 91 | Example of the present invention |
| 12 | L | 60 | 1051 | 1097 | -56 | 98 | Example of the present invention |
| 13 | M | 6 | 1315 | 1317 | -66 | 89 | Example of the present invention |
| 14 | N | 12 | 1410 | 1426 | -56 | 88 | Example of the present invention |
| 15 | O | 25 | 1399 | 1415 | -49 | 89 | Example of the present invention |
| 16 | P | 60 | 1333 | 1348 | -41 | 85 | Example of the present invention |
| 17 | Q | 6 | 1410 | 1451 | -66 | 82 | Example of the present invention |
| 18 | A | 25 | 523 | 601 | -59 | 53* | Comparative example |
| 19 | B | 12 | 538 | 623 | -63 | 49* | Comparative example |
| 20 | C | 25 | 783 | 852 | -67 | 41* | Comparative example |
| 21 | D | 12 | 927 | 953 | -39* | 73* | Comparative example |
| 22 | E | 25 | 936 | 951 | -36* | 75* | Comparative example |
| 23 | F | 12 | 1037 | 1039 | -41 | 67* | Comparative example |
| 24 | G | 25 | 986 | 1012 | -36* | 97 | Comparative example |
| 25 | H | 50 | 953 | 967 | -34* | 96 | Comparative example |
| 26 | I | 12 | 1053 | 1149 | -32* | 95 | Comparative example |
Annotate 1:
*Label table is shown in outside the scope of the invention
Annotate 2: the scope of the invention 1. thickness of slab central part vTrs (℃) tensile strength is less than below 1200MPa-40 ℃
Tensile strength 1200MPa is above below-30 ℃
2. delayed fracture resistance degree of safety index tensile strength is less than 1200MPa more than 80%
Tensile strength 1200MPa is above more than 75%
Table 12
| No. | Steel grade | Thickness of slab (mm) | Yield strength (MPa) | Tensile strength (MPa) | Thickness of slab central part vTrs (℃) | Delayed fracture resistance degree of safety index (%) | Divide |
| 27 | J | 25 | 1153 | 1213 | -33 | 67* | Comparative example |
| 28 | K | 50 | 1183 | 1203 | -35 | 69* | Comparative example |
| 29 | L | 60 | 1012 | 1053 | -23* | 83* | Comparative example |
| 30 | M | 6 | 1213 | 1216 | -28* | 81 | Comparative example |
| 31 | N | 12 | 1308 | 1327 | -25* | 78* | Comparative example |
| 32 | O | 25 | 1297 | 1323 | -24* | 72* | Comparative example |
| 33 | P | 60 | 1216 | 1218 | -26* | 68* | Comparative example |
| 34 | Q | 6 | 1309 | 1311 | -35 | 73* | Comparative example |
| 35 | D | 12 | 1039 | 1058 | -75 | 95 | Example of the present invention |
| 36 | L | 60 | 1048 | 1093 | -47 | 93 | Example of the present invention |
| 37 | R | 35 | 1031 | 1063 | -38* | 64* | Comparative example |
| 38 | S | 50 | 1061 | 1105 | -34* | 61* | Comparative example |
| 39 | T | 50 | 1015 | 1023 | -29* | 53* | Comparative example |
| 40 | U | 60 | 1049 | 1099 | -23* | 55* | Comparative example |
| 41 | X | 25 | 589 | 661 | -112 | 98 | Example of the present invention |
| 42 | Y | 6 | 1411 | 1473 | -51 | 88 | Example of the present invention |
| 43 | Z | 25 | 1459 | 1539 | -53 | 82 | Example of the present invention |
| 44 | AA | 12 | 1371 | 1606 | -55 | 86 | Example of the present invention |
| 45 | BB | 32 | 1403 | 1641 | -47 | 86 | Example of the present invention |
| 46 | CC | 20 | 1451 | 1712 | -51 | 90 | Example of the present invention |
| 47 | DD | 32 | 1115 | 1143 | -70 | 92 | Example of the present invention |
| 48 | EE | 16 | 1405 | 1589 | -32 | 62* | Comparative example |
| 49 | FF | 8 | 1369 | 1551 | -34 | 72* | Comparative example |
| 50 | GG | 12 | 1351 | 1441 | -32 | 71* | Comparative example |
| 51 | HH | 12 | 1179 | 1251 | -52 | 72* | Comparative example |
| 52 | II | 12 | 1181 | 1269 | -39 | 62* | Comparative example |
Annotate 1:
*Label table is shown in outside the scope of the invention
Annotate 2: the scope of the invention 1. thickness of slab central part vTrs (℃) tensile strength is less than below 1200MPa-40 ℃
Tensile strength 1200MPa is above below-30 ℃
2. delayed fracture resistance degree of safety index tensile strength is less than 1200MPa more than 80%
Tensile strength 1200MPa is above more than 75%
Claims (20)
1. high tensile steel, it is in quality %, contain Elements C: 0.02～0.25%, Si:0.01～0.8%, Mn:0.5～2.0%, Al:0.005～0.1%, N:0.0005～0.008%, P:0.02% following, below the S:0.004%, surplus is made of Fe and unavoidable impurities, and the mean value of the length-to-diameter ratio of original austenite grain is more than 3 in whole thickness of slab direction.
2. high tensile steel as claimed in claim 1, wherein, below the S:0.003%, and the cementite fraction of coverage at lath interface is below 50%.
3. high tensile steel as claimed in claim 1 or 2, its steel is formed in quality %, contains also that Mo:1% is following, Nb:0.1% is following, V:0.5% is following, Ti:0.1% is following, Cu:2% is following, Ni:4% is following, Cr:2% is following, W:2% one or more in following.
4. as each described high tensile steel in the claim 1～3, its steel is formed in quality %, contains also that B:0.003% is following, Ca:0.01% is following, REM:0.02% is following, Mg:0.01% one or more in following.
5. as each described high tensile steel in the claim 1～4, wherein, make contain hydrogen in the steel after, by zinc-plated hydrogen is enclosed in the steel, then, carry out 1 * 10
-3/ second following low strain rate tension test, the delayed fracture resistance degree of safety index of being obtained by following formula is more than 75%,
Delayed fracture resistance degree of safety index (%)=100 * (X
1/ X
0)
In the formula, X
0: do not contain the relative reduction in area of the test film of diffustivity hydrogen in fact, X
1: the relative reduction in area that contains the test film of diffustivity hydrogen.
6. high tensile steel as claimed in claim 5, wherein, described delayed fracture resistance degree of safety index is more than 80%.
7. the manufacture method of the described high tensile steel of claim 5 wherein, after casting has the steel of each described composition in the claim 1～4, is not cooled to Ar
3Below the transformation temperature, perhaps, reheat is to Ac
3More than the transformation temperature, beginning hot rolling then, is the thickness of slab that regulation is made in rolling hot rolling more than 30% by the rolling rate in the non-recrystallization district of being included in, then from Ar
3Transformation temperature is above to be cooled to temperature below 350 ℃ with the speed of cooling more than 1 ℃/second, then at Ac
1Carry out tempering below the transformation temperature.
8. the manufacture method of the described high tensile steel of claim 6, wherein, at the described Ac of claim 7
1In the tempering method below the transformation temperature, use and roller mill and refrigerating unit are arranged on the heating unit on the same production line, set from 370 ℃ to Ac
1The average heating speed of the thickness of slab central part of the regulation tempering temperature that transformation temperature is following is more than 1 ℃/second, and carrying out tempering and making the Da Wendu that is up to of thickness of slab central part is more than 400 ℃.
9. the manufacture method of the described high tensile steel of claim 6, wherein, at the described Ac of claim 8
1In the following tempering method of transformation temperature, further setting the average heating speed that begins the thickness of slab central part of temperature to 370 ℃ from tempering is more than 2 ℃/second.
10. high tensile steel, it is in quality %, contain Elements C: 0.02～0.25%, Si:0.01～0.8%, Mn:0.5～2.0%, Al:0.005～0.1%, N:0.0005～0.008%, P:0.02% following, below the S:0.004%, surplus is made of Fe and unavoidable impurities, and the mean value of the length-to-diameter ratio of original austenite grain is more than 3 in whole thickness of slab direction.
11. high tensile steel as claimed in claim 10, its steel is formed in quality %, contains also that Mo:1% is following, Nb:0.1% is following, V:0.5% is following, Ti:0.1% is following, Cu:2% is following, Ni:4% is following, Cr:2% is following, W:2% one or more in following.
12. as claim 10 or 11 described high tensile steels, its steel is formed in quality %, contains also that B:0.003% is following, Ca:0.01% is following, REM:0.02% is following, Mg:0.01% one or more in following.
13. as each described high tensile steel in the claim 10～12, wherein, make contain hydrogen in the steel after, by zinc-plated hydrogen is enclosed in the steel, then, carry out 1 * 10
-3/ second following low strain rate tension test, the delayed fracture resistance degree of safety index of being obtained by following formula is more than 75%,
Delayed fracture resistance degree of safety index (%)=100 * (X
1/ X
0)
In the formula, X
0: do not contain the relative reduction in area of the test film of diffustivity hydrogen in fact, X
1: the relative reduction in area that contains the test film of diffustivity hydrogen.
14. the manufacture method of the described high tensile steel of claim 13 wherein, after casting has the steel of each described composition in the claim 10～12, is not cooled to Ar
3Below the transformation temperature, perhaps, reheat is to Ac
3More than the transformation temperature, beginning hot rolling then, is the thickness of slab that regulation is made in rolling hot rolling more than 30% by the rolling rate in the non-recrystallization district of being included in, then from Ar
3Transformation temperature is above to be cooled to temperature below 350 ℃ with the speed of cooling more than 1 ℃/second, then at Ac
1Carry out tempering below the transformation temperature.
15. high tensile steel, it is in quality %, contain Elements C: 0.02～0.25%, Si:0.01～0.8%, Mn:0.5～2.0%, Al:0.005～0.1%, N:0.0005～0.008%, P:0.02% following, below the S:0.003%, surplus is made of Fe and unavoidable impurities, the mean value of the length-to-diameter ratio of original austenite grain is more than 3 in whole thickness of slab direction, and the cementite fraction of coverage at lath interface is below 50%.
16. high tensile steel as claimed in claim 15, its steel is formed in quality %, contains also that Mo:1% is following, Nb:0.1% is following, V:0.5% is following, Ti:0.1% is following, Cu:2% is following, Ni:4% is following, Cr:2% is following, W:2% one or more in following.
17. as claim 15 or 16 described high tensile steels, its steel is formed in quality %, contains also that B:0.003% is following, Ca:0.01% is following, REM:0.02% is following, Mg:0.01% one or more in following.
18. as each described high tensile steel in the claim 15～17, wherein, make contain hydrogen in the steel after, by zinc-plated hydrogen is enclosed in the steel, then, carry out 1 * 10
-3/ second following low strain rate tension test, the delayed fracture resistance degree of safety index of being obtained by following formula is more than 80%,
Delayed fracture resistance degree of safety index (%)=100 * (X
1/ X
0)
In the formula, X
0: do not contain the relative reduction in area of the test film of diffustivity hydrogen in fact, X
1: the relative reduction in area that contains the test film of diffustivity hydrogen.
19. the manufacture method of the described high tensile steel of claim 18 wherein, after casting has the steel of each described composition in the claim 15～17, is not cooled to Ar
3Below the transformation temperature, perhaps, reheat is to Ac
3More than the transformation temperature, beginning hot rolling then, is the thickness of slab that regulation is made in rolling hot rolling more than 30% by the rolling rate in the non-recrystallization district of being included in, then from Ar
3Transformation temperature is above to be cooled to temperature below 350 ℃ with the speed of cooling more than 1 ℃/second, and use and roller mill and refrigerating unit are arranged on the heating unit on the same production line then, setting from 370 ℃ to Ac
1The average heating speed of the thickness of slab central part of the regulation tempering temperature that transformation temperature is following is more than 1 ℃/second, and carrying out tempering and making the Da Wendu that is up to of thickness of slab central part is more than 400 ℃.
20. the manufacture method of the described high tensile steel of claim 18 wherein, after casting has the steel of each described composition in the claim 15～17, is not cooled to Ar
3Below the transformation temperature, perhaps, reheat is to Ac
3More than the transformation temperature, beginning hot rolling then, is the thickness of slab that regulation is made in rolling hot rolling more than 30% by the rolling rate in the non-recrystallization district of being included in, then from Ar
3Transformation temperature is above to be cooled to temperature below 350 ℃ with the speed of cooling more than 1 ℃/second, use and roller mill and refrigerating unit are arranged on the heating unit on the same production line then, set the average heating speed that begins the thickness of slab central part of temperature to 370 ℃ from tempering and be more than 2 ℃/second and from 370 ℃ to Ac
1The average heating speed of the thickness of slab central part of the regulation tempering temperature that transformation temperature is following is more than 1 ℃/second, and carrying out tempering and making the Da Wendu that is up to of thickness of slab central part is more than 400 ℃.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2007021573 | 2007-01-31 | ||
| JP021573/2007 | 2007-01-31 | ||
| JP086296/2007 | 2007-03-29 | ||
| JP2007086296 | 2007-03-29 | ||
| PCT/JP2008/052002 WO2008093897A1 (en) | 2007-01-31 | 2008-01-31 | High tensile steel products excellent in the resistance to delayed fracture and process for production of the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101600812A true CN101600812A (en) | 2009-12-09 |
| CN101600812B CN101600812B (en) | 2012-09-05 |
Family
ID=39785004
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2008800037329A Active CN101600812B (en) | 2007-01-31 | 2008-01-31 | High tensile steel products excellent in the resistance to delayed fracture and process for production of the same |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP5277648B2 (en) |
| CN (1) | CN101600812B (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105861938A (en) * | 2016-03-31 | 2016-08-17 | 苏州睿昕汽车配件有限公司 | Corrosion-resistant alloy steel material for automobile parts and preparation method thereof |
| CN106676415A (en) * | 2015-11-06 | 2017-05-17 | 攀钢集团攀枝花钢铁研究院有限公司 | Atmosphere corrosion resisting chromium-nitrogen-containing molten profile steel, atmosphere corrosion resisting profile steel and production method of atmosphere corrosion resisting profile steel |
| CN107699795A (en) * | 2017-10-26 | 2018-02-16 | 江西省中蔚建设集团有限公司 | A kind of processing method of high strength cast iron for building |
| CN110121568A (en) * | 2016-12-27 | 2019-08-13 | 杰富意钢铁株式会社 | High strength galvanized steel plate and its manufacturing method |
| CN110139942A (en) * | 2016-12-22 | 2019-08-16 | 株式会社Posco | High hardness wear-resisting steel and its manufacturing method |
| CN110684924A (en) * | 2019-09-25 | 2020-01-14 | 中国石油天然气集团有限公司 | X100 steel grade tee pipe fitting material manufactured by electric melting additive and using method |
| CN112725686A (en) * | 2020-11-17 | 2021-04-30 | 邯郸钢铁集团有限责任公司 | Crane jib steel with yield strength of 960MPa and production method thereof |
| CN114585760A (en) * | 2019-10-22 | 2022-06-03 | 株式会社Posco | Steel sheet for pressure vessel having excellent resistance to high-temperature postweld heat treatment and method for producing same |
| CN115449705A (en) * | 2015-09-17 | 2022-12-09 | 杰富意钢铁株式会社 | Steel structure for hydrogen having excellent hydrogen embrittlement resistance in high-pressure hydrogen gas, and method for producing same |
Families Citing this family (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8141618B2 (en) * | 2008-06-24 | 2012-03-27 | Nucor Corporation | Strip casting method for controlling edge quality and apparatus therefor |
| JP5081175B2 (en) * | 2008-07-28 | 2012-11-21 | 株式会社神戸製鋼所 | Method for evaluating hydrogen cracking resistance of steel |
| WO2010032428A1 (en) * | 2008-09-17 | 2010-03-25 | 新日本製鐵株式会社 | High-strength steel plate and process for producing same |
| WO2010055609A1 (en) | 2008-11-11 | 2010-05-20 | 新日本製鐵株式会社 | Thick steel sheet having high strength and method for producing same |
| JP5609383B2 (en) * | 2009-08-06 | 2014-10-22 | Ｊｆｅスチール株式会社 | High strength hot rolled steel sheet with excellent low temperature toughness and method for producing the same |
| JP5604849B2 (en) * | 2009-10-22 | 2014-10-15 | Ｊｆｅスチール株式会社 | High-tensile thick steel plate with excellent hydrogen penetration inhibition characteristics and method for producing the same |
| JP5564022B2 (en) * | 2010-12-10 | 2014-07-30 | 株式会社神戸製鋼所 | Method for evaluating hydrogen cracking resistance of forged steel |
| WO2012153009A1 (en) | 2011-05-12 | 2012-11-15 | Arcelormittal Investigación Y Desarrollo Sl | Method for the production of very-high-strength martensitic steel and sheet thus obtained |
| JP5692002B2 (en) * | 2011-10-28 | 2015-04-01 | 新日鐵住金株式会社 | High-tensile steel plate with excellent weldability and manufacturing method thereof |
| JP5874664B2 (en) * | 2013-03-15 | 2016-03-02 | Ｊｆｅスチール株式会社 | High strength steel plate with excellent drop weight characteristics and method for producing the same |
| JP5928405B2 (en) * | 2013-05-09 | 2016-06-01 | Ｊｆｅスチール株式会社 | Tempered steel sheet excellent in resistance to hydrogen-induced cracking and method for producing the same |
| MX2016009700A (en) | 2014-01-28 | 2016-09-22 | Jfe Steel Corp | Wear-resistant steel plate and process for producing same. |
| JP6582590B2 (en) * | 2015-06-17 | 2019-10-02 | 日本製鉄株式会社 | Steel sheet for LPG storage tank and method for producing the same |
| CN105385956A (en) * | 2015-12-12 | 2016-03-09 | 郭策 | Diversion pressure pipeline of hydropower station |
| CA3001529C (en) | 2015-12-21 | 2020-06-02 | Nippon Steel & Sumitomo Metal Corporation | As-rolled type k55 electric resistance welded oil well pipe and hot-rolled steel sheet |
| HUE052103T2 (en) * | 2018-01-23 | 2021-04-28 | Ssab Technology Ab | Hot-rolled steel & method for manufacturing hot-rolled steel |
| CN112639430A (en) * | 2018-11-30 | 2021-04-09 | 日本精工株式会社 | Hydrogen environment degree determination method and white tissue damage possibility prediction method |
| CN117265432A (en) * | 2022-06-15 | 2023-12-22 | 宝山钢铁股份有限公司 | Delayed cracking resistant and abrasion resistant steel for dredging high-hardness slurry and manufacturing method thereof |
| CN115094346B (en) * | 2022-07-04 | 2023-06-20 | 宁波祥路中天新材料科技股份有限公司 | Hot rolled strip steel with tensile strength more than or equal to 1200MPa and produced by adopting TSR production line and method |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02236223A (en) * | 1989-03-07 | 1990-09-19 | Nippon Steel Corp | Production of high strength steel excellent in delayed fracture characteristic |
| JP3233828B2 (en) * | 1995-09-13 | 2001-12-04 | 新日本製鐵株式会社 | High-strength PC steel rod excellent in delayed fracture characteristics of spot welds and method of manufacturing the same |
| JP3233826B2 (en) * | 1995-09-13 | 2001-12-04 | 新日本製鐵株式会社 | High-strength PC steel rod excellent in delayed fracture characteristics of spot welds and method of manufacturing the same |
| JP3719037B2 (en) * | 1999-03-10 | 2005-11-24 | Ｊｆｅスチール株式会社 | Continuous cast slab having no surface crack and method for producing non-tempered high strength steel using this slab |
| JP4696570B2 (en) * | 2005-01-26 | 2011-06-08 | Ｊｆｅスチール株式会社 | Manufacturing method of high-tensile steel material with excellent hydrogen embrittlement resistance |
-
2008
- 2008-01-30 JP JP2008018426A patent/JP5277648B2/en active Active
- 2008-01-31 CN CN2008800037329A patent/CN101600812B/en active Active
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115449705A (en) * | 2015-09-17 | 2022-12-09 | 杰富意钢铁株式会社 | Steel structure for hydrogen having excellent hydrogen embrittlement resistance in high-pressure hydrogen gas, and method for producing same |
| CN106676415A (en) * | 2015-11-06 | 2017-05-17 | 攀钢集团攀枝花钢铁研究院有限公司 | Atmosphere corrosion resisting chromium-nitrogen-containing molten profile steel, atmosphere corrosion resisting profile steel and production method of atmosphere corrosion resisting profile steel |
| CN106676415B (en) * | 2015-11-06 | 2019-03-15 | 攀钢集团攀枝花钢铁研究院有限公司 | Containing chrome and nitrogen atmosphere corrosion resistance structural steel molten steel and atmosphere corrosion resistance structural steel and its production method |
| CN105861938A (en) * | 2016-03-31 | 2016-08-17 | 苏州睿昕汽车配件有限公司 | Corrosion-resistant alloy steel material for automobile parts and preparation method thereof |
| US11332802B2 (en) | 2016-12-22 | 2022-05-17 | Posco | High-hardness wear-resistant steel and method for manufacturing same |
| CN110139942A (en) * | 2016-12-22 | 2019-08-16 | 株式会社Posco | High hardness wear-resisting steel and its manufacturing method |
| CN110121568A (en) * | 2016-12-27 | 2019-08-13 | 杰富意钢铁株式会社 | High strength galvanized steel plate and its manufacturing method |
| US11377708B2 (en) | 2016-12-27 | 2022-07-05 | Jfe Steel Corporation | High-strength galvanized steel sheet and method for producing the same |
| CN107699795A (en) * | 2017-10-26 | 2018-02-16 | 江西省中蔚建设集团有限公司 | A kind of processing method of high strength cast iron for building |
| CN110684924A (en) * | 2019-09-25 | 2020-01-14 | 中国石油天然气集团有限公司 | X100 steel grade tee pipe fitting material manufactured by electric melting additive and using method |
| CN110684924B (en) * | 2019-09-25 | 2021-07-02 | 中国石油天然气集团有限公司 | X100 steel grade tee pipe fitting material manufactured by electric melting additive and using method |
| CN114585760A (en) * | 2019-10-22 | 2022-06-03 | 株式会社Posco | Steel sheet for pressure vessel having excellent resistance to high-temperature postweld heat treatment and method for producing same |
| CN112725686A (en) * | 2020-11-17 | 2021-04-30 | 邯郸钢铁集团有限责任公司 | Crane jib steel with yield strength of 960MPa and production method thereof |
| CN112725686B (en) * | 2020-11-17 | 2022-06-14 | 邯郸钢铁集团有限责任公司 | Steel with yield strength of 960MPa for crane boom and production method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101600812B (en) | 2012-09-05 |
| JP2008208454A (en) | 2008-09-11 |
| JP5277648B2 (en) | 2013-08-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101600812B (en) | High tensile steel products excellent in the resistance to delayed fracture and process for production of the same | |
| JP6048580B2 (en) | Hot rolled steel sheet and manufacturing method thereof | |
| CN103703156B (en) | The high tensile steel plate had excellent moldability, high strength galvanized steel plate and their manufacture method | |
| KR101388334B1 (en) | High tensile steel products excellent in the resistance to delayed fracture and process for production of the same | |
| JP6008039B2 (en) | High-strength hot-rolled steel sheet with a maximum tensile strength of 980 MPa or more with excellent bake hardenability and low-temperature toughness | |
| CN100523256C (en) | Oil well seamless steel pipe excellent in resistance to sulfide stress cracking and method for production thereof | |
| JP5124988B2 (en) | High-tensile steel plate with excellent delayed fracture resistance and tensile strength of 900 MPa or more and method for producing the same | |
| JP6107437B2 (en) | Manufacturing method of low-alloy high-strength seamless steel pipe for oil wells with excellent resistance to sulfide stress corrosion cracking | |
| CN104583424A (en) | Steel, sheet steel product and process for producing a sheet steel product | |
| CN101928875A (en) | High-strength cold-rolled steel sheet with good forming performance and preparation method thereof | |
| CN103276291A (en) | Heavy gauge, high tensile strength, hot rolled steel sheet with excellent HIC resistance and manufacturing method therefor | |
| JP5277672B2 (en) | High strength steel plate with excellent delayed fracture resistance and method for producing the same | |
| JPWO2013125399A1 (en) | Cold-rolled steel sheet and manufacturing method thereof | |
| JP5181775B2 (en) | High strength steel material excellent in bending workability and low temperature toughness and method for producing the same | |
| US10400298B2 (en) | High-carbon hot-rolled steel sheet and method for producing the same | |
| JP2009242841A (en) | High-tensile steel excellent in bending workability and low-temperature toughness, and method for manufacturing the same | |
| CN114402089B (en) | Thick steel plate and method for producing thick steel plate | |
| WO2022070608A1 (en) | Steel sheet and steel sheet manufacturing method | |
| JP6468302B2 (en) | Material for steel pipe for high strength oil well and method for producing steel pipe for high strength oil well using the material | |
| US20210054473A1 (en) | Steel composition in accordance with api 5l psl-2 specification for x-65 grade having enhanced hydrogen induced cracking (hic) resistance, and method of manufacturing the steel thereof | |
| WO2020209149A1 (en) | Cold rolled steel sheet and method for producing same | |
| JP5076480B2 (en) | High-strength steel sheet excellent in strength-ductility balance and deep drawability and method for producing the same | |
| CN100523259C (en) | High tensile steel product excellent in delayed fracture resistance and method for production thereof | |
| KR100448623B1 (en) | Method for manufacturing high Si added medium carbon wire rod to reduce decarburization depth of its surface | |
| JPH04358026A (en) | Production of seamless low alloy steel tube having fine-grained structure |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |