CN101591756A - Low-crackle sensitive steel board with yield strength of 620 MPa grade and manufacture method thereof - Google Patents
Low-crackle sensitive steel board with yield strength of 620 MPa grade and manufacture method thereof Download PDFInfo
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Abstract
Low-crackle sensitive steel board with yield strength of 620 MPa grade and manufacture method thereof, its chemical ingredients mass percent is: C 0.01～0.05, Si 0.10～0.45, Mn 0.60～1.20, Cr 0.30～0.50, Mo 0.10～0.30, Nb 0.01～0.04, Al 0.02～0.04, Cu 0.60～1.20, Ni:0.60～1.20, B 0.0005～0.0010, Ti 0.005～0.015, surplus is Fe and inevitable impurity, Pcm≤0.20%.The present invention adopts control thermo-mechanical rolling and cooling technology, obtained matrix based on the bainite of refinement, thereby helping armor plate strength, plasticity and flexible improves, greater than 700MPa, Xia Shi ballistic work Akv (20 ℃) 〉=180J, welding property is good greater than 620MPa, tensile strength for the steel plate yield strength.
Description
Technical field
The present invention relates to low carbon high-strength degree structure iron, specifically, the present invention relates to the low-crackle sensitive steel and the manufacture method thereof of board with yield strength of 620 MPa grade.
Background technology
The low-crackle sensitive high-strength steel is mainly used in physical constructions such as colliery, exploration and the engineering construction, require this steel to have higher intensity, hardness, toughness and welding property, according to the difference of using the position, the scope of requirement of strength is also different, for the ease of welding with simplify weldprocedure, wish that the welding crack sensibility indices P cm of steel is low as far as possible, to reach the purpose that need not preheating before the weldering, this steel is called as the low-welding crack-sensitive high-strength steel, also claims CF steel.It is a class have superior weldability can and the Hi-Stren steel of low-temperature flexibility, not preheating or preheating and not cracking a little mainly were the welding procedure problems that has solved large-scale steel structure members before its advantage was to weld; For the board with yield strength of 620 MPa grade steel plate, the Pcm of general requirement steel≤0.25%.
The only resource that reduces Pcm is exactly the add-on that reduces carbon and alloying element, and for the high-strength steel that adopts quenching+tempering process to produce, reduce the add-on of carbon and alloying element and will bring the reduction of hardness of steel inevitably, if adopt hot mechanical controlled rolling and controlled cooling technology (TMCP), then can remedy this defective, in addition, with respect to modified (quenching+tempering) technology, hot mechanical controlled rolling and controlled cooling technology (TMCP) thus also have the benefit that crystal grain thinning improves the low-temperature flexibility of steel.
At present, adopting the alloying constituent of the low welding crack sensitivity steel of TMCP technology production generally is Mn-Mo-Nb-Cu-Ni-V-B system or Mn-Mo-Nb-Cu-Ni-B system.
A kind of low-welding crack-sensitive high-strength steel is disclosed as Chinese patent CN1396294, its chemical ingredients mass percent is: two or more in C 0.02～0.13, Mn 0.60～1.80, Si 0.10～0.60, Ti0.005～0.025, Al≤0.01, Ti 0.005～0.025, N 0.0020～0.0060, B 0.0005～0.0020, Nb 0.008～0.040 and Ni≤0.55, V≤0.10, Cu≤0.65, Mo≤0.50%, Zr≤0.040, RE≤0.020, Pcm=0.33%.
And for example Chinese patent CN1932063A relates to the chemical ingredients mass percent of steel grade and is: C:0.06～0.09, Si 0.15～0.55, Mn 1.00～1.60, P≤0.015, S≤0.006, Ni 0.15～0.40, Cr≤0.30, Mo≤0.30, Cu≤0.30, V 0.02～0.06, Nb 0.005～0.05, Als0.010～0.040, Pcm=0.25;
Another large-line energy welds non-modulation high-ductility steel, its chemical ingredients mass percent is: C 0.02～0.18, Si 0.10～0.60, Mn 0.60～1.80, P≤0.020, S≤0.010, Ni≤0.60, Mo≤0.50, Cu≤0.80, V 0.02～0.08, Nb≤0.040, Als 0.010～0.060, Pcm=0.32;
The alloying element design of above-mentioned disclosed three kinds of steel grades is respectively Mn-Mo-Cu-Ni-Nb-V-B system and Mn-Mo-Cr-Cu-Ni-Nb-V-B system, and these two kinds of steel require respectively steel plate is quenched+tempering or temper, and manufacturing process's complexity increases production cost.
The following thickness specification of the 40mm that has developed, yield strength 550Mpa level low-crackle sensitive steel, its composition quality per-cent is: C 0.005～0.05, Si 0.05～0.70, Mn 1.40～1.85, Cr0.30～0.50, Mo 0.60～1.20, Nb 0.04～0.08, Al 0.02～0.06, Cu≤0.30, Ni 0.60～1.20, Ti 0.005～0.015.
The mechanical property of this steel is: yield strength 580Mpa, tensile strength 650Mpa,-20 ℃ of impact of collision merit average out to 290J, its mechanical property mean value meets other requirement of 550Mpa level, but can not adapt to the higher key part of requirement of strength in the physical construction, the alloying constituent Mo of this steel, Mn content are higher in addition, cause this steel cost to increase.
In addition, the surface of steel plate and the central tissue of the above thickness of 30mm are inconsistent, be that surface of steel plate is ferrite bainite and martensitic stucture, the centre is mainly polygonal ferrite and a small amount of bainite structure, cause on the steel plate thickness performance inhomogeneous, particularly low-temperature impact toughness is relatively poor, and brittle crack takes place easily.
Summary of the invention
The object of the present invention is to provide a kind of low-crackle sensitive steel board with yield strength of 620 MPa grade and manufacture method thereof, need not thermal treatment, steel plate has good low-temperature flexibility and weldability.
For achieving the above object, technical scheme of the present invention is, adopting Mn-Nb-Cr-Mo-V-Ti-B is steel grade, consider cost factor, reduce the add-on of alloying element from the composition design as far as possible, by reducing expensive Alloy Elements Mo, increase the Cr constituent content, to reach the purpose that reduces production costs; Make full use of the purpose that the compound adding technology of various microalloy elements reaches reinforcement, adopt the compound adding of Nb, Ti, B, Mo element, guarantee the enterolithic accumulation in non-recrystallization district, and guarantee that steel grade obtains bainite structure, utilize the strain inducing of microalloy elements such as Nb, Ti, Mo, Cu to separate out and the timeliness strengthening effect, further improve intensity; By optimizing manufacture method, promptly in conjunction with the composition of steel, adopt controlled rolling of two stages and on-line Control process for cooling (TMCP technology), to obtain more than the yield strength 620Mpa, to have a Hi-Stren steel of superior weldability energy and low-temperature flexibility, TMCP technology has been saved thermal treatment process, saved production cost, do not needed preheating when the steel plate of TMCP explained hereafter welds in addition, so reduced welding cost.
Particularly, a kind of low-crackle sensitive steel board with yield strength of 620 MPa grade of the present invention, its chemical ingredients mass percent is: C 0.01～0.05, Si 0.10～0.45, Mn 0.60～1.20, Cr0.30～0.50, Mo 0.10～0.30, Nb 0.01～0.04, Al 0.02～0.04, Cu 0.30～0.80, Ni 0.60～1.20, B 0.0005～0.0010, Ti 0.005～0.015, surplus is Fe and unavoidable impurities, and satisfies welding crack sensibility indices P cm≤0.20%.
The welding crack sensibility indices P cm of low-crackle sensitive steel can determine by following formula:
Pcm＝C+Si/30+Ni/60+(Mn+Cr+Cu)/20+Mo/15+V/10+5B
Welding crack sensibility indices P cm is the judgement index of the welding cold cracking tendency of reflection steel, and Pcm is low more, and weldability is good more, otherwise then weldability is poor more.Be difficult for when weldability is meant welding well producing welding crack, and the steel of weldability difference is easy to generate crackle, for fear of the generation of crackle, must before welding, carry out preheating to steel, weldability is good more, and then required preheating temperature is low more, otherwise then needs higher preheating temperature.It is generally acknowledged that when Pcm≤0.20%, the following steel of board with yield strength of 620 MPa can be realized pre-thermo-welding.
In the present invention,
C: the effect in steel is solution strengthening, but C is unfavorable to welding property.C content is high more, and welding property is poor more, and for the bainitic steel that adopts the TMCP explained hereafter, the low more then toughness of C content is good more, and lower carbon content can be produced the ductility steel plate of bigger thickness, so C content of the present invention is controlled to be 0.03～0.05%.
Mo: improve the hardening capacity of steel, the present invention only need add and is no more than 0.25% Mo, because Mo is unfavorable to welding property, Mo is a kind of very expensive element simultaneously, its price is the several times of Cr, so the present invention replaced part Mo with Cr, to reach the purpose that reduces cost.
Cr: as weak carbide forming element, add hardening capacity, promotion martensite/bainite formation that Cr not only improves steel plate, and the position increases to difference between martensite/lath of bainite, increase the resistance that crackle passes martensite/bainite colony, when improving armor plate strength, the have some improvement effect of steel plate toughness of tool;
Nb: the present invention is by adding more Nb, to reach the purpose of crystal grain thinning and increase steel plate thickness, be the non-recrystallization temperature that improves steel on the other hand on the one hand, be convenient in the operation of rolling, adopt higher relatively finishing temperature, thereby the quickening roll speed is enhanced productivity.In addition, owing to strengthened the grain refining effect, make the thickness that can produce steel plate increase, adopt the chemical ingredients of the present invention's design, the maximum ga(u)ge that can produce steel plate is 80mm.
Si: the effect in steel mainly is solution strengthening, also can improve the hardening capacity of steel, adds in the steel of the present invention to be no more than intensity and the toughness that 0.45% Si helps improving steel.
Ti: in steel, can produce the effect of intensive precipitation strength, the intensity of steel is improved, can also stop austenite recrystallization.It can produce the grain refining effect, improve the steel yield strength, as a kind of important microalloy element, titanium can form carbon, the nitride particles of tiny titanium, thereby can obtain comparatively tiny austenitic microstructure by the alligatoring that stops austenite crystal in slab reheat process.In addition, the existence of the nitride particles of titanium can suppress the grain coarsening of welded heat affecting zone.Thereby titanium can improve the low-temperature flexibility of matrix metal and welded heat affecting zone simultaneously.Because titanium can be with the fixing nomadic nitrogen atom of the nitride form of titanium, formed so it can stop nomadic nitrogen boron nitride and to the disadvantageous effect of the hardening capacity generation of steel.
Cu: be austenite stabilizer element, add Cu and also can reduce Ar3 point temperature, improve the hardening capacity of steel plate and the resistance to atmospheric corrosion of steel plate; The compound interpolation of Cu, Ni except that the copper brittleness phenomenon that reduces Copper Bearing Steel, alleviate the effect of intergranular cracking of the operation of rolling, the more important thing is that Cu, Ni are austenite stabilizer element, the compound interpolation of Cu, Ni can reduce Ar3 significantly, improve the motivating force of austenite to ferrite transformation, cause martensite/lath of bainite can to each the position to growing up, cause between martensite/lath of bainite the position to become big, increase the resistance that crackle passes martensite/lath of bainite to difference.
B: can significantly increase the hardening capacity of steel, the present invention adds 0.0005～0.0010 B, combines with Mo, can make steel under certain cooling conditions, obtains the high strength bainite structure with comparalive ease.
The chemical ingredients C content of steel of the present invention has reduced with respect to original, the reduction of C content mainly is toughness and a welding property of considering to improve steel, the intensity that influences for the reduction that remedies because of C content, by adding the best fit of Mn, Nb, Mo, Cr, alloying elements such as B, Cu, make the good comprehensive mechanical performance of steel plate tool.Mn is in the controlled rolling steel, and content is generally below 1.5%, because manganese content surpasses at 1.5% o'clock, hardening of steel and ductility degenerates then is so the content of Mn is controlled at 0.8%～1.20% among the present invention; Nb can produce significant grain refining and medium precipitation strength effect, but niobium has the tendency that increases the welded heat affecting zone reheat crack(ing), when adding niobium separately in the weld seam, toughness is significantly degenerated, but when coexisting, Ti-Nb-Mo can present good toughness, the permission content of niobium in boron-containing steel can not surpass 0.04%, so the content of Nb is controlled at below 0.04% among the present invention;
Mo and B have significant retardation function to perlitic transformation, and less to the influence of bainite transformation, thereby can obtain the tissue of whole bainites in sizable speed of cooling scope.In containing the B steel, Mo is particularly remarkable to the influence of hardening capacity, and when Mo and Nb add fashionablely simultaneously, Mo can increase the restraining effect to austenite recrystallization in the controlled rolling process, and then promotes the refinement of austenitic microstructure.Simultaneously Mo is a kind of very expensive element, and its price is the several times of Cr, so the present invention replaced part Mo with Cr, reaching the purpose that reduces cost, but when the Cr addition above 0.80% the time, the weldability of grievous injury steel plate; Therefore steel Cr content of the present invention is controlled at about 0.45%.Cr matches with Ni, B and Mo, has increased the stability of supercooled austenite, has suppressed the transformation of proeutectoid ferrite, obtains uniform bainite structure.
In containing the B steel, can utilize the ageing strengthening effect of ε-Cu, make the intensity of this class steel reach higher level, the copper content that the steel of different stage adopts is about 0.3%～0.8%, and the copper in the steel can be significantly and the B shaft raising cooperation usefulness that adds, and the ferrite that can further suppress before the bainite transformation forms, in order to prevent the red brittleness of Copper Bearing Steel, added an amount of Ni in the steel, prevented the red brittleness that copper content height causes, in order to guarantee the intensity of steel; B content is controlled between 0.0005%～0.0013%, when guaranteeing steel plate hardening capacity, thereby obtains uniform bainite structure easilier in process of cooling, to guarantee the intensity and the toughness of steel plate.B content of the present invention is 0.0005%～0.0010%.
Comprehensive above each element and mutual effect have in higher intensity and hardness steel plate of the present invention, have good toughness and welding property simultaneously.
The manufacture method of low-crackle sensitive steel board with yield strength of 620 MPa grade of the present invention comprises smelting, casting, heating, rolling, refrigerating work procedure, it is characterized in that, promptly enters refrigerating work procedure without thermal treatment behind described rolling process; Wherein, rolling finishing temperature is 790～830 ℃; In the process of cooling, steel plate is quickened cooling, be cooled to 450～550 ℃, air cooling after the water outlet with the speed of 8～20 ℃/S.
Further, the thickness of continuously cast bloom after the casting or steel ingot is not less than 4 times of Finished Steel plate thickness.
Again, the present invention is in described heat-processed, and Heating temperature is 1180～1200 ℃, and soaking time is 120～150 minutes.
The present invention is rolling to be divided into the fs and subordinate phase is rolling; In the fs operation of rolling, start rolling temperature is 1050～1150 ℃, when rolled piece thickness arrives 2～3 times of Finished Steel plate thickness, treats that on roller-way temperature is to 800～850 ℃; In the subordinate phase operation of rolling, pass deformation rate is 15～25%, and finishing temperature is 790～830 ℃.
In addition, air cooling adopts stacking or cold bed cooling.
In the manufacture method of low-crackle sensitive steel board with yield strength of 620 MPa grade of the present invention,
Finishing temperature is controlled at the low-temperature zone in non-recrystallization district, this humidity province is near transformation temperature Ar3 simultaneously, be that finishing temperature is 790～830 ℃, finish to gauge in this temperature range, both provided higher energy accumulation for phase transformation, also be unlikely to bring too high load, relatively be suitable for slab production to milling train.
Process for cooling
After the rolling end, steel plate enters accelerated cooling device, is cooled to 450～550 ℃ by 8～20 ℃/second speed.Speed of cooling can be avoided ferrite and pearlitic formation faster, directly enters the bainite transformation district of CCT curve.The bainitic transformation motivating force can be expressed as
ΔG＝ΔG
chem+ΔG
d
Δ G in the formula
ChemBe chemical driving force, Δ G
dBe that the strain that defective causes stores energy.
Big speed of cooling makes austenite cold excessively, has increased chemical phase driving force, and the strain that causes in conjunction with the operation of rolling stores energy Δ G
dConsider, the motivating force of bainite forming core is increased.The combination of Mo and B element has improved the hardening capacity of steel, more helps the transformation of bainite in process of cooling, thus make in the steel plate thickness range organize more even.
Because steel plate has accumulated very high dislocation of density and high strain energy in the operation of rolling, highdensity dislocation will with precipitate Nb (CN) particle interaction of Nb, finish to quickening in refrigerative air cooling (relaxation) process rolling, this interaction impels at the inner tiny Polygons dislocation cell structures in a large number that form of austenite crystal, the Nb atom has been stablized this Polygons cell structure with certain misorientation poly-partially and a large amount of fine Nb (CN) the separating out on the dislocation cell wall on the dislocation wall.Simultaneously, the moderate finite deformation of a passage has the effect of inducing ferrite transformation, under this inducing action, the Ar3 point increases, so-called " strain-induced transformation " phenomenon promptly appears, at the bigger deflection in non-recrystallization humidity province, will help the intracrystalline forming core of acicular ferrite, can make martensite island on the bainite matrix even dispersion more that distributes simultaneously.
Adopting faster, cooling rate is for higher condensate depression is provided for bainite transformation, increase phase driving force, obtain more highdensity nucleation rate, thereby obtain matrix, make steel plate of the present invention have higher intensity and good toughness based on the bainite of refinement.But, roll when the back is quick cools off, make that the cooling of surface of steel plate and intermediary is widely different, cause thickness direction tissue odds even easily.The present invention, in microalloy C-Mn steel, add the B element, match with Mo, Ni, Cr, increased the stability of supercooled austenite, suppressed the transformation of proeutectoid ferrite, can be in very wide cooling rate scope (1 ℃/s～25 ℃/generate bainite structure in s) help steel plate thickness direction homogeneous microstructure unanimity, thereby guarantee the homogeneity of performance on the steel plate thickness direction.In order to guarantee the cooled intensity of steel plate, require the tissue of steel plate should be, so the speed of cooling optimum range of steel of the present invention is defined as 8 ℃/s～20 ℃/s based on tiny ferrite bainite.
Rolling technology
The present invention adopts two stage rolling, i.e. recrystallize type controlled rolling, the controlled rolling of non-recrystallization type.
The deformation characteristics of recrystallize type controlled rolling is, dynamic recovery and incomplete dynamic recrystallization take place in distortion steel, between rolling back or twice time static recovery and static recrystallize takes place.Along with the carrying out of distortion and recrystallize, the temperature of steel constantly descends, and austenite crystal is refinement progressively, and the austenite crystal interfacial area increases, for austenite provides more multi-position to the ferritic phase deformed nucleus.The controlled rolling of non-recrystallization type is to be rolled in the lowest temperature scope of austenitic area, and the temperature range that recrystallize does not take place is generally in 950 ℃-Ar3 interval, and its variation of temperature depends on the size of the Chemical Composition and the deflection of steel.The deformation characteristics of non-recrystallization type controlled rolling is, recrystallize does not take place the deformed austenite after rolling, and austenite crystal is crushed and elongates.Be out of shape when big, intragranular produces a large amount of slip band and dislocation, has increased effective grain boundary area, and ferrite is at forming core on the crystal boundary and on the deformation bands during phase transformation.
Subordinate phase of the present invention is rolling when 2～3 times of rolled piece thickness arrival Finished Steel plate thickness, treats that on roller-way temperature is to 800～850 ℃.For containing the Nb steel, its non-recrystallization temperature is about 950～1050 ℃, rolling steel billet temperature is reduced to 800～850 ℃, purpose is in order to guarantee that it has enough deflections in the non-recrystallization district, more highdensity dislocation accumulative total is arranged, for ferrite transformation provides more favourable forming core condition in the austenite of distortion.Bigger distortion also helps the separating out of carboritride of Nb, because the effect that deformation inductdion is separated out, bigger pass deformation rate will help forming more tiny and disperse precipitate, have the carbonitride of Nb, V and Ti to separate out separately with compound in the relaxation process simultaneously and separate out.The carbonitride pinning of separating out the motion of dislocation and subgrain boundary, kept a large amount of dislocations at the austenite crystal intragranular, and provide a large amount of nucleation sites for the formation of bainite in the process of cooling.Simultaneously, precipitate tiny and disperse provides highdensity forming core place and stops ferrite crystal grain ground to be grown up and alligatoring by it to ground, the interface pinning effect of growing up for ferrite, and this strength and toughness for steel all plays favourable effect.
Beneficial effect of the present invention
1, passes through rational designing chemical composition, reduce C content significantly, and substitute part Mo with cheap alloying elements such as Mn and Cr, C, the fine precipitation particles of N chemical combination with Ti are made precipitation strength, B, Nb and Mo have improved the hardening capacity of steel, add the precipitation strength effect of Cu, make this steel reach higher intensity and good plasticity, and welding crack sensibility is less, need not preheating before the weldering.
2, steel plate of the present invention need not carry out any extra thermal treatment, thereby has simplified manufacturing process, has reduced the manufacturing cost of steel.
3, because composition and technological design are reasonable, and from implementation result, process system is looser, can in, Plate Steel produces stably manufactured on the line.
4, low-crackle sensitive steel yield strength of the present invention can reach the 80mm plate greater than 620MPa, tensile strength greater than 720MPa, Xia Shi ballistic work Akv (20 ℃) 〉=180J, thickness of slab, and steel plate cross section hardness is even.
Description of drawings
Fig. 1 is the hard observed value in cross section of the low-crackle sensitive steel of the embodiment of the invention 6.
Embodiment
Embodiment 1
Press chemical ingredients electric furnace or the converter smelting shown in the table 1, and be cast into continuously cast bloom or steel ingot, and continuously cast bloom or steel ingot are heated to 1180 ℃, be incubated 120 minutes, in, to carry out the fs on the thick milling train rolling, start rolling temperature is 1150 ℃, when rolled piece thickness is 60mm, treats that on roller-way temperature is to 850 ℃, it is rolling to carry out subordinate phase subsequently, subordinate phase rolling pass deformation rate is 15～20%, and finishing temperature is 830 ℃, and the Finished Steel plate thickness is 20mm.After the rolling end, steel plate enters and quickens cooling (ACC) device, is cooled to 500 ℃, stacking or cold bed cooling after the water outlet with the speed of 20 ℃/S.
Embodiment 2
Embodiment is with embodiment 1, and wherein Heating temperature is 1150 ℃, is incubated 150 minutes; Fs, rolling start rolling temperature was 1080 ℃, and rolled piece thickness is 90mm; The rolling start rolling temperature of subordinate phase is 840 ℃, and pass deformation rate is 10～12%, and finishing temperature is 810 ℃, and the Finished Steel plate thickness is 30mm; The steel plate speed of cooling is 15 ℃/S, and final temperature is 490 ℃.
Embodiment 3
Embodiment is with embodiment 1, and wherein Heating temperature is 1150 ℃, is incubated 120 minutes; Fs, rolling start rolling temperature was 1100 ℃, and rolled piece thickness is 120mm; The rolling start rolling temperature of subordinate phase is 830 ℃, and pass deformation rate is 10～15%, and finishing temperature is 820 ℃, and the Finished Steel plate thickness is 40mm; The steel plate speed of cooling is 15 ℃/S, and final temperature is 530 ℃.
Embodiment 4
Embodiment is with embodiment 1, and wherein Heating temperature is 1120 ℃, is incubated 150 minutes; Fs, rolling start rolling temperature was 1070 ℃, and rolled piece thickness is 150mm; The rolling start rolling temperature of subordinate phase is 830 ℃, and pass deformation rate is 10～15%, and finishing temperature is 800 ℃, and the Finished Steel plate thickness is 50mm; The steel plate speed of cooling is 18 ℃/S, and final temperature is 515 ℃.
Embodiment is with embodiment 1, and wherein Heating temperature is 1150 ℃, is incubated 140 minutes; The start rolling temperature of stage rolling is 1100 ℃, and rolled piece thickness is 150mm; The rolling start rolling temperature of subordinate phase is 800 ℃, and pass deformation rate is 10～15%, and finishing temperature is 800 ℃, and the Finished Steel plate thickness is 60mm; The steel plate speed of cooling is 20 ℃/S, and final temperature is 490 ℃.
Embodiment 6
Embodiment is with embodiment 1, and wherein Heating temperature is 1180 ℃, is incubated 150 minutes; Fs, rolling start rolling temperature was 1080 ℃, and rolled piece thickness is 180mm; The rolling start rolling temperature of subordinate phase is 790 ℃, and pass deformation rate is 10～15%, and finishing temperature is 790 ℃, and the Finished Steel plate thickness is 80mm; The steel plate speed of cooling is 20 ℃/S, and final temperature is 480 ℃.
Chemical ingredients of the low-crackle sensitive steel of table 1 embodiment of the invention 1-6 and Comparative Examples 7-9 (wt%) and Pcm thereof
| Embodiment | C | Si | Mn | Nb | Ni | Cu | Al | Ti | Cr | Mo | B | Fe | Pcm |
| 1 | 0.04 | 0.30 | 1.20 | 0.030 | 0.65 | 0.65 | 0.03 | 0.08 | 0.35 | 0.25 | 0.0005 | Surplus | 0.19 |
| 2 | 0.03 | 0.40 | 1.15 | 0.02 | 0.70 | 0.75 | 0.03 | 0.09 | 0.034 | 0.22 | 0.0008 | Surplus | 0.17 |
| 3 | 0.04 5 | 0.20 | 1.20 | 0.040 | 0.68 | 0.60 | 0.023 | 0.10 | 0.45 | 0.20 | 0.0006 | Surplus | 0.19 |
| 4 | 0.03 | 0.40 | 1.10 | 0.035 | 0.65 | 0.60 | 0.03 | 0.06 | 0.39 | 0.25 | 0.0009 | Surplus | 0.16 |
| 5 | 0.05 | 0.40 | 1.00 | 0.030 | 0.66 | 0.60 | 0.025 | 0.08 | 0.35 | 0.25 | 0.0005 | Surplus | 0.19 |
| 6 | 0.04 | 0.32 | 1.15 | 0.02 | 0.80 | 0.75 | 0.03 | 0.09 | 0.34 | 0.22 | 0.0008 | Surplus | 0.17 |
| 7 | 0.07 | 0.32 | 1.52 | 0.04 | 0.04 | 0.30 | 0.03 | 0.08 | - | 0.45 | - | Surplus | 0.28 |
| 8 | 0.065 | 0.40 | 1.50 | 0.03 | 0.05 | 0.20 | 0.025 | 0.06 | 0.20 | 0.40 | - | Surplus | 0.26 |
| 9 | 0.055 | 0.35 | 1.48 | 0.03 | 0.04 | 0.20 | 0.03 | 0.07 | 0.02 | 0.50 | - | Surplus | 0.31 |
Low-crackle sensitive steel to embodiment of the invention 1-6 and Comparative Examples 7-9 carries out Mechanics Performance Testing, and test result sees Table 2.
The mechanical property of the low-crackle sensitive steel of table 2 embodiment of the invention 1-6 and Comparative Examples 7-9
| Embodiment | Yield strength (MPa) | Tensile strength (MPa) | Unit elongation (%) | -20 ℃ of impact of collision merit/tough break ratios (J/%) |
| 1 | 685， 675 | 760， 745 | 18.0， 19.5 | 353/100， 333/100， 352/100 300/100 |
| 2 | 675， 670 | 740， 735 | 17.0， 18.5 | 364/100， 346/100， 342/100 |
| 3 | 670， 680 | 725， 740 | 17.0， 17.0 | 309/100， 300/100， 302/100 |
| 4 | 660， 670 | 735， 740 | 18.5， 19.0 | 319/100， 320/100， 308/100 |
| 5 | 640， 645 | 760， 770 | 18.5， 19.5 | 330/100， 354/100， 340/100 |
| 6 | 640， 640 | 740， 745 | 21.0， 20.0 | 309/100， 317/100， 304/100 |
| 7 | 580 575 | 690 655 | 22.0 21.0 | 250/100， 220/100， 198/100 |
| 8 | 615 620 | 680 675 | 20.0 21.0 | 280/100， 300/100， 307/100 |
| 9 | 620 630 | 710 695 | 20.0 21.0 | 220/100， 235/100， 200/100 |
From table 1, table 2 as can be seen, the Pcm of embodiment of the invention low-crackle sensitive steel≤0.20%, yield strength is all greater than 620MPa, tensile strength is greater than 720MPa, Xia Shi ballistic work Akv (20 ℃) 〉=180J, thickness of slab can reach 80mm, has good low-temperature flexibility and weldability.And Pcm 〉=0.25% of former embodiment 7-9 low-crackle sensitive steel, yield strength all is lower than 630MPa, tensile strength is lower than 710MPa, impact property has reached requirement, but welding property is in lower limit, thickness of slab at most also is to roll to 40mm, and the steel over-all properties of original design composition can not reach other requirement of 620MPa level thus.
Test example 2
By standard GB/T 4340-1999 the cross section hardness of the low-crackle sensitive steel of the embodiment of the invention 6 is measured, observed value is seen Fig. 1.
As can be seen from Figure 1, the cross section hardness of steel plate of the present invention is even.
Test example 3
Low-crackle sensitive steel to the embodiment of the invention 1 carries out welding performance test (little iron grinds test), under 0 ℃, room temperature and 50 ℃ of conditions, does not all find crackle (seeing Table 3), illustrates that the welding property of steel grade of the present invention is good, does not generally need preheating during welding.
Table 3 embodiment of the invention 1 low-crackle sensitive steel welding performance test (little iron grinds test) result
In sum, the present invention increases the Cr constituent content by reducing expensive Alloy Elements Mo, reduces production costs; Make full use of the purpose that the compound adding technology of various microalloy elements reaches reinforcement, adopt the compound adding of Nb, Ti, B, Mo element, guarantee the enterolithic accumulation in non-recrystallization district, and guarantee that steel grade obtains bainite structure, utilize the strain inducing of microalloy elements such as Nb, Ti, Mo, Cu to separate out and the timeliness strengthening effect, further improve intensity; By optimizing manufacture method, promptly in conjunction with the composition of steel, adopt controlled rolling of two stages and on-line Control process for cooling (TMCP technology), to obtain more than the yield strength 620Mpa, to have a Hi-Stren steel of superior weldability energy and low-temperature flexibility; TMCP technology has been saved thermal treatment process, has saved production cost, does not need preheating when the steel plate of TMCP explained hereafter welds in addition, so reduced welding cost.
Claims (6)
1. low-crackle sensitive steel board with yield strength of 620 MPa grade, its chemical ingredients mass percent is: C0.01～0.05, Si 0.10～0.45, Mn 0.60～1.20, Cr 0.30～0.50, Mo 0.10～0.30, Nb 0.01～0.04, Al 0.02～0.04, Cu 0.30～0.80, Ni 0.60～1.20, B 0.0005～0.0010, Ti 0.005～0.015, surplus is Fe and inevitable impurity, and satisfies welding crack sensibility indices P cm≤0.20%.
2. the manufacture method of low-crackle sensitive steel board with yield strength of 620 MPa grade as claimed in claim 1 comprises smelting, casting, heating, rolling, refrigerating work procedure, it is characterized in that, promptly enters refrigerating work procedure without thermal treatment behind described rolling process; Wherein, rolling finishing temperature is 790～830 ℃; In the process of cooling, steel plate is quickened cooling, be cooled to 450～550 ℃, air cooling after the water outlet with the speed of 8～20 ℃/S.
3. the manufacture method of low-crackle sensitive steel board with yield strength of 620 MPa grade as claimed in claim 2 is characterized in that, the continuously cast bloom after the casting or the thickness of steel ingot are not less than 4 times of Finished Steel plate thickness.
4. the manufacture method of low-crackle sensitive steel board with yield strength of 620 MPa grade as claimed in claim 2 is characterized in that, in described heat-processed, Heating temperature is 1180～1200 ℃, and soaking time is 120～150 minutes.
5. the manufacture method of low-crackle sensitive steel board with yield strength of 620 MPa grade as claimed in claim 2 is characterized in that, rollingly is divided into the fs and subordinate phase is rolling; In the fs operation of rolling, start rolling temperature is 1050～1150 ℃, when rolled piece thickness arrives 2～3 times of Finished Steel plate thickness, treats that on roller-way temperature is to 800～850 ℃; In the subordinate phase operation of rolling, pass deformation rate is 15～25%, and finishing temperature is 790～830 ℃.
6. the manufacture method of low-crackle sensitive steel board with yield strength of 620 MPa grade as claimed in claim 2 is characterized in that, air cooling adopts stacking or cold bed cooling.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102766807A (en) * | 2012-07-31 | 2012-11-07 | 内蒙古包钢钢联股份有限公司 | Boron contained bainite steel plate and manufacturing method thereof |
| CN106086325A (en) * | 2016-07-22 | 2016-11-09 | 柳州科尔特锻造机械有限公司 | A kind of Nb Ti micro alloyed steel Technology for Heating Processing |
| CN110724878A (en) * | 2019-10-30 | 2020-01-24 | 鞍钢股份有限公司 | 0.5Ni low-temperature steel and manufacturing method thereof |
| CN113737103A (en) * | 2017-09-08 | 2021-12-03 | 杰富意钢铁株式会社 | Steel sheet and method for producing same |
| CN115181888A (en) * | 2021-04-02 | 2022-10-14 | 宝山钢铁股份有限公司 | Low-carbon low-alloy hot-dip aluminum-zinc or zinc-aluminum-magnesium complex phase steel with yield strength of 450MPa and manufacturing method thereof |
| CN115608780A (en) * | 2022-12-19 | 2023-01-17 | 太原科技大学 | Method for controlling copper-containing stainless steel cracks and stainless steel |
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2008
- 2008-05-26 CN CNA2008100380471A patent/CN101591756A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102766807A (en) * | 2012-07-31 | 2012-11-07 | 内蒙古包钢钢联股份有限公司 | Boron contained bainite steel plate and manufacturing method thereof |
| CN106086325A (en) * | 2016-07-22 | 2016-11-09 | 柳州科尔特锻造机械有限公司 | A kind of Nb Ti micro alloyed steel Technology for Heating Processing |
| CN113737103A (en) * | 2017-09-08 | 2021-12-03 | 杰富意钢铁株式会社 | Steel sheet and method for producing same |
| CN110724878A (en) * | 2019-10-30 | 2020-01-24 | 鞍钢股份有限公司 | 0.5Ni low-temperature steel and manufacturing method thereof |
| CN115181888A (en) * | 2021-04-02 | 2022-10-14 | 宝山钢铁股份有限公司 | Low-carbon low-alloy hot-dip aluminum-zinc or zinc-aluminum-magnesium complex phase steel with yield strength of 450MPa and manufacturing method thereof |
| CN115608780A (en) * | 2022-12-19 | 2023-01-17 | 太原科技大学 | Method for controlling copper-containing stainless steel cracks and stainless steel |
| CN115608780B (en) * | 2022-12-19 | 2023-03-21 | 太原科技大学 | Method for controlling copper-containing stainless steel cracks and stainless steel |
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Open date: 20091202 |