CN100352963C - Soft magnetic structural steel resisting salt fog corrosion and its making process - Google Patents
Soft magnetic structural steel resisting salt fog corrosion and its making process Download PDFInfo
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Abstract
The present invention relates to soft magnetic structural steel, and is especially one kind of soft magnetic structural steel resisting salt fog and its making process. The present invention solves the technological problem of raising the salt fog corrosion resistance of soft magnetic structural steel. The soft magnetic structural steel consists of C 0.020-0.040 wt%, Si 1.40-1.60 wt%, Mn 0.40-0.80 wt%, P not more than 0.015 wt%, S not more than 0.005 wt%, Als 0.040-0.060 wt%, Cu 0.20-0.50 wt%, Ti 0.035-0.055 wt%, N not more than 0.0035 wt%, Ni 0.80- 1.20 wt%, and Ca or REM 10-60ppm, except Fe and inevitable impurities. Its making process includes continuous casting, re-crystallization controlling rolling, accelerated cooling or intermittent direct quenching, and subsequent slow cooling step. The present invention is especially suitable for use as side guide plate in magnetic suspension train track beam in high salt fog area.
Description
Technical field
The present invention relates to a kind of soft magnetic structural steel and manufacture method thereof, present invention is specifically related to a kind of magnetic suspension rail special use, have higher intensity, good electromagnetic performance and low-temperature flexibility, a good weldability, have high magneticflux-density, high resistivity and good diamagnetic ageing, atmospheric corrosion resistance again, especially suit to use in the coastland, to have good salt spray corrosion resistance (mainly be anti-Cl
-Ion etching) soft magnetic structural steel plate is especially suitable for use as the side guide plate on the maglev guide way girder of coastal high salt fog area.
Background technology
Be used for maglev common soft magnetic structural steel plate and appear at Germany at first, Thyssen iron and steel stock company respectively at nineteen eighty-two and 1999 at U. S. application patent US 4350525 magnetic levitation rail parts (Magnetic suspensionrailroad parts) and US 6287395 " but Magnetically Soft Steel and the application on magnetic levitation rail parts thereof of high energy welding ", disclosed soft magnetic structural steel plate invention process, US 4350525 and US 6287395 have set forth the effect of each alloying element in the soft magnetic structural steel.But by the soft magnetic structural steel plate that this patented technology is produced, quality in kind is lower, and it is lower to show as impelling strength, and especially the low-temperature impact toughness below 0 ℃ is very low, and 0 ℃ of transverse impact merit (Akv) may be brought hidden danger to train operation between 12J～57J; Magnetic strength is not high yet simultaneously, and B40 has only about 1.60T, and especially low B3 of magnetic strength has only 0.60T under the downfield, and electromagnetic conversion efficiency is on the low side, and invalid loss is big, and electric energy loss is big, can not adapt to the increasingly stringent environmental protection requirement.
Baosteel is at the Chinese patent ZL01126937.5 " high performance soft steel magnet for magnetic suspension train " of calendar year 2001 application, the German invention of soft magnetic structural steel plate performance that is used for magnetic suspension rail has raising significantly, but its magneticflux-density, still not high enough (about 1.60T～the 1.61T of B40 of resistivity and low-temperature impact toughness, about 0.9T～the 1.00T of B3, about 0.39～0.40 μ Ω m of electricalresistivity, 0 ℃ of Akv 〉=140J), when especially impelling strength is being lower than-10 ℃, can not guarantee 〉=27J, weldability is also relatively poor, weld heat input can only be controlled at≤and 12kJ/cm could guarantee the 0 ℃ of Akv 〉=27J in heat affected zone (HAZ) therefore, and this kind soft magnetic structural steel plate uses in the colder north and still has big potential safety hazard.
Baosteel is at the Chinese patent ZL02136192.4 of application in 2002, the soft magnetic structural steel plate performance that is used for magnetic suspension rail has raising significantly than Baosteel at the Chinese patent ZL01126937.5 of calendar year 2001 application, its magneticflux-density, resistivity has and increases substantially (about 1.65T～the 1.68T of B40, about 1.15T～the 1.30T of B3, about 0.42～0.45 μ Ω m of electricalresistivity), though the low-temperature impact toughness increase rate is very big, Akv (20 ℃)＞150J, weldability also is improved largely, can adopt than the large-line energy welding, (analog parameter: peak temperature is 1350 ℃ to simulation welded heat affecting zone (HAZ)-20 ℃ Akv＞27J, t
8/5Be 50 seconds, single loop); but mother metal below-20 ℃ and the impelling strength Akv of welding joint fluctuation are very big; especially there is local brittle zone (LBZ) in welded heat affecting zone; Akv below-20 ℃ can not satisfy 〉=27J; while operation more complicated; production cost is also higher, needs off-line normalizing thermal treatment.
Baosteel is at the Chinese patent ZL03116097.2 of application in 2003; not only manufacturing process is simple; production cost is also lower; need not off-line normalizing thermal treatment; and plate property also has raising significantly than Baosteel at the Chinese patent ZL02136192.4 of application in 2002; especially the low-temperature impact toughness increase rate is very big; Akv (30 ℃) 〉=100J; weldability also is improved largely; can adopt than the large-line energy welding, (analog parameter: peak temperature is 1350 ℃, t to simulation welded heat affecting zone (HAZ)-30 ℃ Akv 〉=21J
8/5Be 50 seconds, single loop), but mother metal below-30 ℃ and the impelling strength Akv of welding joint fluctuation are very big, especially there is local brittle zone (LBZ) in welded heat affecting zone, Akv below-30 ℃ can not total energy satisfy 〉=27J, and the alloy system of especially discovering high Si content has determined the low-temperature flexibility of soft magnetic structural steel plate can't stably satisfy safe in utilization at cold district below-30 ℃.
Baosteel is at the Chinese patent ZL200410017999.7 of application in 2003, adopt extremely low C, medium Si content, high Als, high Mn, medium Cr content, ferromagnetic element Ni alloying, add Ca or rare earth elements RE M handles, and adopt control Ti/N technique means such as between 2.5～3.2, optimize recrystallize controlled rolling and accelerated cooling process " RCR+ACC or RCR+IDQ (Interrupted Direct Quenching) " and follow-up retarded cooling process, the grain-size that makes the finished product soft magnetic structural steel plate obtains excellent mechanical property, electromagnetic performance and weldability at 10～30 μ m.Akv 〉=150J of-40 ℃ can adopt than the large-line energy welding, and (analog parameter: peak temperature is 1350 ℃, t to simulation welded heat affecting zone (HAZ)-40 ℃ Akv 〉=50J
8/5Be 50 seconds, single loop), satisfied safe in utilization at cold district below-30 ℃.
Though but the anti-normal atmospheric corrodibility of foregoing soft magnetic structural steel is better, salt fog resistance (mainly is anti-Cl
-Ion etching) relatively poor, can not form the anti-oxidation film of one deck densification on the surface, promptly common soft magnetic structural steel is the same with in the past weather resisting steel, the rust corrosion under many salt time-sharing environment be since under corrosion layer Cl
-(chlorion) brought out the active site of galvanic corrosion, easily forms one deck poor stability, loose unsound β-Fe (OH) at surface of steel plate
3The iron rust layer has promptly formed Cl
-Nest (nest) is at this Cl
-Under the nest effect, airborne O
2, Cl
2Constantly invade Deng corrosive medium, cause erosion rate to increase.Result's corrosion layer fine and close continuously inadequately, the protectiveness difference is continuous to be generated and advances to steel plate inside, can not be applicable to coastal high salt fog area use.Therefore in order to form the high rusty scale of protectiveness under the many environment of salinity in air, must suppress Cl
-The penetrativity of (chlorion).
Domestic and international coastal low temp area is economically developed mostly, populous, and magnetic suspension train has the area of development potentiality most.Therefore, it is very urgent to develop the special-purpose soft magnetic structural steel plate of coastal high salt fog area magnetic suspension train.
Summary of the invention
The object of the present invention is to provide a kind of suiting in the soft magnetic structural steel and the manufacture method thereof of the regional resisting salt fog corrosion that uses of coastal high salt fog, the technical issues that need to address are that the existing soft magnetic structural steel plate salt fog resistance of solution (mainly is anti-Cl
-Ion etching) problem of wretched insufficiency when soft magnetic structural steel plate has high strength, high/low-temperature impact toughness, good weldability and good electromagnetic property, also will have high salt fog resistance, is specially adapted to the coastland of high salt fog.Guarantee the security that soft magnetic structural steel plate uses at severe cold area (below 30 ℃).Simultaneously, simplify production technique, reduce production costs.Thinking of the present invention is to adopt ultralow C, 1.40%～1.60%Si content, low Mn, Cu and high Ni alloying, the Ti of adding 0.035%～0.055%, control N content is lower than 0.0035%, and technique means such as employing Ca or rare earth elements RE M processing, optimize recrystallize controlled rolling and accelerated cooling process " RCR (recrystallize controlled rolling)+ACC (quickening cooling) or RCR+IDQ (being interrupted direct quenching Interrupted Direct Quenching) " and follow-up retarded cooling process, the grain-size that makes the finished product soft magnetic structural steel plate is at 10～25 μ m, obtain excellent mechanical property, electromagnetic performance and weldability, especially has high salt fog resistance, aforementioned to satisfy to the requirement of soft magnetic structural steel all properties, be specially adapted to the high salt mist environment of riviera
◆ carbon: well-known carbon is very big to electromagnetic performance, low-temperature impact toughness and the weldability influence of soft magnetic structural steel, from electromagnetic performance, low-temperature impact toughness and the weldability angle of improving steel, wishes that C content is relatively lower in the steel to be advisable; But from the intensity of soft magnetic structural steel, prior microstructures Control angle from course of hot rolling and normalizing process, C content should not be low excessively, because Si content is than higher in the soft magnetic structural steel, crosses low C content (＜0.02%) and cause Ac
1, Ac
3, Ar
1, Ar
3Higher, this brings big problem for the even thinning microstructure of hot rolling and normalizing, easily forms mixed grain structure, causes the low and welded heat affecting zone low-temperature impact toughness deterioration of soft magnetic structural steel low-temperature impact toughness; Secondly, C crosses to hang down and will cause grain growth speed to accelerate, and causes microstructure coarsening, the deterioration low-temperature impact toughness; C content is crossed and is hanged down anti-atmospheric corrosion simultaneously, and especially salt air corrosion is also unfavorable.Comprehensive above factor, and consider C maximum solid solution degree about 0.02% in ferrite, so the content of C is controlled at
0.020%～0.040%Between.
◆ silicon: the Si in the steel can improve the resistivity and the magnetic permeability of steel, reduce magnetostriction, eddy-current loss and magnetic hysteresis loss, add electromagnetic performance and the resistivity that a certain amount of Si can greatly improve steel in the soft magnetic structural steel, and low excessively silicon (＜1.40%) is unfavorable to reducing magnetostriction, eddy-current loss and magnetic hysteresis loss; But because Si is strong ferrite stabilizer, adds Si (＞1.60%) too much and not only can cause magneticflux-density to reduce, cause Ac
1, Ac
3, Ar
1, Ar
3Higher, this brings big problem for the even thinning microstructure of hot rolling and normalizing, easily forms mixed grain structure, causes the low and welded heat affecting zone low-temperature impact toughness deterioration of soft magnetic structural steel low-temperature impact toughness; Secondly, Si is the EMBRITTLEMENT ELEMENTS in the steel, and too much alloying causes very big fragility not only for steel itself, and the weldability of grievous injury steel, and Si has the C of inhibition to separate out from austenite and ferrite in addition, improves the hardenability of steel, promotes the A/M island to form.Amid all these factors, Si content is controlled in the steel
1.40%～1.60%Between.
◆ manganese: Mn as alloying element in soft magnetic structural steel except that improving its resistivity, intensity and improving the toughness, also have the austenite of expansion phase region, reduce Ac
1, Ac
3, Ar
1, Ar
3The point temperature, the effect of refinement ferrite crystal grain; But under high Ni content condition (～1.00%Ni), the magneticflux-density that adds too much Mn (＞0.80%) meeting reduction soft magnetic structural steel, improve the hardenability of soft magnetic structural steel, influence the weldability of soft magnetic structural steel, when especially little heat input welds, easily form crisp sclerous tissues such as martensite, balance is considered above-mentioned factor, and Mn content is controlled at
0.40%～0.80%Between.
◆ phosphorus: P is as harmful electromagnetic performance, mechanical property that is mingled with soft magnetic structural steel in the steel, especially low-temperature impact toughness and weldability have huge detrimental effect, it is low more good more to require in theory, but considers that the logistics of steel-making condition, steel-making cost and steelworks is smooth and easy, requires P content to be controlled at
≤ 0.015%
◆ sulphur: S has very big detrimental effect as harmful electromagnetic performance that is mingled with soft magnetic structural steel in the steel, the more important thing is that S combines with Mn in steel, form the MnS inclusion, in course of hot rolling, the plasticity-of MnS makes MnS along rolling to extension, form along rolling to MnS inclusion band, the transverse impact toughness of grievous injury steel plate, Z are to performance and weldability, and S produces hot short principal element in the course of hot rolling simultaneously.It is low more good more to require in theory, but considers the smooth and easy principle of logistics of steel-making condition, steel-making cost and steelworks, requires S content to be controlled at
≤ 0.005%
◆ copper: therefore soft magnetic structural steel requires it to have extremely good atmospheric corrosion resistance as magnetic-levitation beam sides guide plate, and Cu is very effective weather-proof element, adds certain Cu and can greatly improve its resistance to atmospheric corrosion in soft magnetic structural steel; But add too much Cu (〉=0.50%), electromagnetic performance with the infringement soft magnetic structural steel, as reduce magneticflux-density and improve coercive force, because Cu is not a ferromagnetic element, add Cu in the steel, the magneticflux-density of steel will be reduced, surpass 0.50% if add Cu content, in hot rolling and normalizing treatment process, ε-Cu that small and dispersed takes place is precipitated (Cu is solid solubility～0.50% in ferrite), and the pinning magnetic domain wall movement further reduces the magneticflux-density of steel, improve coercive force, also may cause copper brittleness simultaneously.If but add Cu content very few (＜0.20%), soft magnetic structural steel resistance to atmospheric corrosion deficiency, so Cu content is controlled at
Between 0.20%～0.50%.
◆ chromium: Cr is the same substantially with the Cu role, adds certain content Cr element in soft magnetic structural steel, also can improve the soft magnetic structural steel atmospheric corrosion resistance.But Cr in salt mist environment in role and the non-salt mist environment role just in time opposite, promptly in salt mist environment, Cr reduces the pH value of corrosion leading surface significantly, accelerates Cl
-The formation of nest (nest), the fltting speed of accelerated corrosion leading surface reduces the resistance to corrosion of soft magnetic structural steel in salt fog atmosphere.Therefore in the steel of the present invention
Do not add the Cr element
◆ nickel: Ni is unique element that can improve intensity, the low-temperature flexibility of steel simultaneously and improve the weldability of steel; While Ni or ferromagnetic element, the Fe-Ni alloy is a kind of soft magnetic materials of excellent property, in ferrous alloy, add the electromagnetic performance that Ni not only can not reduce material, and can further improve electromagnetic performance, add Ni in the steel and can also reduce the copper brittleness generation, alleviate the cracking of course of hot rolling, improve the resistivity of Magnetically Soft Steel and improve resistance to atmospheric corrosion, especially in salt mist environment, Ni makes the corrosion layer densification and has suppressed water, oxygen and Cl
-The penetrativity of corrosive mediums such as (ions).When Ni content greater than 0.80% the time, soft magnetic structural steel plate salt fog resistance corrodibility increases considerably.Therefore theoretically, in the steel Ni content within the specific limits (＜1.50%) high more good more, but Ni is a kind of very noble element, considers from the ratio of performance to price, suitable add-on is
0.80%～1.20%
◆ titanium: in the salt air corrosion environment, add a certain amount of Ti (0.035%～0.055%) and can prevent poor stability, loose unsound β-Fe (OH)
3The iron rust layer forms, and promotes the corrosion layer that stability is high, compactness is good to form, and suppresses Cl
-Ion is invaded, and improves the soft magnetic structural steel plate salt fog resistance greatly.In addition, when adding the Ti of trace in the steel, Ti combines with N in the steel, generates the very high TiN particle of stability, and inhibition welded heat affecting zone (HAZ) austenite crystal is grown up and changed the second-order phase transition product, improves the weldability of soft magnetic structural steel.Add Ti content very few (＜0.005%), form TiN number of particles deficiency, the austenite crystal that is not enough to suppress HAZ is grown up and is changed the second-order phase transition product and improve the low-temperature flexibility of HAZ; When adding Ti content too much (＞0.055%), in the solidification of molten steel process, liquation goes out large size TiN particle, and this large size TiN particle not only can not suppress the austenite crystal of HAZ grows up, and becomes the starting point of crack initiation on the contrary; In addition, it is too much to generate TiN quantity, will cause the electromagnetic performance of soft magnetic structural steel to descend and the coercive force rising.So salt fog resistance and weldability angle from improving soft magnetic structural steel, the while is not damaged the electromagnetic performance of soft magnetic structural steel again, and Ti content span of control is
0.0350%～0.055%
◆ the span of control of nitrogen: N is corresponding with the span of control of Ti, its basic starting point is to suppress the TiN particle in molten steel or molten steel solidification process, separate out from liquid molten steel that (the TiN particle of separating out is the quantity rareness not only from molten steel, main is that size is very thick, the austenite crystal that this thick TiN particle not only can not suppress HAZ is grown up, and becomes the starting point of crack initiation on the contrary); But will be controlled at after molten steel solidifies fully, from solid phase, separate out.So, the not only tiny but also disperse of the TiN particle of separating out, crystal grain thinning and the weldability of improving soft magnetic structural steel effectively.According to above-mentioned analysis, the TiN particle is separated out the beginning temperature should be lower than 1450 ℃, according to log[%Ti] [%N]=4.72-16192/T, N content should be controlled at below 0.004%.But when N content was high, free [N] increased in the steel, soft magnetic structural steel may produce serious magnetic aging in the use afterwards, and N content increases in the steel simultaneously, and free [N] content in welded H AZ district sharply increases, grievous injury HAZ low-temperature impact toughness, the weldability of deterioration soft magnetic structural steel.The above analysis, the N content in the steel is controlled at
≤ 0.0035%
◆ Ca or RFM: steel is carried out Ca or REM processing, on the one hand can further pure molten steel, on the other hand sulfide in the steel is carried out denaturing treatment, make it to become non deformable, stablize tiny spherical sulfide, improve Magnetically Soft Steel electromagnetic performance, suppress S red brittleness, improve Magnetically Soft Steel impelling strength and Z to performance, improve the anisotropy of soft magnetic structural steel impelling strength.What of Ca or REM add-on are depended on the height of S content in the steel, and Ca or REM add-on are low excessively, and treatment effect is little; Ca or REM add-on are too high, and (O, S) oversize, fragility also increases, and can become the fracture crack starting point, reduces the low-temperature flexibility of steel, also reduces purity of steel simultaneously, pollutes molten steel to form Ca or REM.General control Ca or REM content are pressed ESSP=(wt%Ca), and [1-124 (wt%O)/1.25 (wt%S), wherein ESSP is a sulfide inclusion shape control index, be advisable between the span 0.5～5, so the span of control of Ca or REM content is
0.001%≤Ca≤0.006% (0.001%≤REM≤0.06%)
◆ sour molten aluminium Als: the Als in the soft magnetic structural steel is the freedom [N] in the steel fixedly, prevent to form the nitride infringement magnetic of iron and prevent that freedom [N] from producing magnetic aging under temperature and stress, and has the resistivity that improves the soft magnetism steel plate, reduce welded heat affecting zone (HAZ) free [N] simultaneously, improve the low-temperature impact toughness effect of HAZ; Not only can reduce the magneticflux-density of steel but add excessive Als in the steel, and can in steel, form the needle-like Al of a large amount of disperses
2O
3Inclusion, electromagnetic performance, low-temperature impact toughness and the weldability of infringement steel the more important thing is that Al is strong reductor, are guaranteeing Als fixedly in the steel under the situation of free N, i.e. Al 〉=2 (Ntotal-0.292Ti) should reduce Als content as much as possible.According to soft magnetic structural steel composition system, optimum Al s content is controlled at
0.040%～0.60%Between.
◆ Pcm≤0.20%, preferably Pcm≤0.18%, wherein Pcm=wt%C+wt%Si/30+ (wt%Mn+wt%Cu+wt%Cr)/20+wt%Ni/60+wt%Mo/15+wt%V/10+5wt%B.
◆ the microstructure type of soft magnetic structural steel (mother metal steel plate): even tiny equiaxed ferritic grain.Soft magnetic structural steel plate as on the high-speed maglev train track girder had both required to have excellent mechanical property, and especially low-temperature impact toughness requires to have good electromagnetic performance again.Therefore, the microstructure of soft magnetic structural steel plate is different from common welded construction steel plate, also is different from common non-oriented electromagnetic steel sheet.For common welded construction steel plate, in order to improve the low-temperature impact toughness of its mother metal and welded heat affecting zone, it is favourable forming superfine little ferrite crystal grain (＜10 μ m) or tiny low-carbon bainite tissue; And for common non-oriented electromagnetic steel sheet, in order to improve its electromagnetic performance, it is favourable forming axle ferrite (＞100 μ m) such as evenly thick.For soft magnetic structural steel plate, if its microstructure is superfine little ferrite crystal grain (＜10 μ m) or tiny low-carbon bainite tissue, though can improve its mechanical property, especially low-temperature impact toughness, but electromagnetic performance severe exacerbation, especially the magneticflux-density under the downfield reduces greatly, because ferrite grain size too small (＜10 μ m), grain boundary area increases, the effect of crystal boundary pinning magnetic domain wall movement is strengthened, for tiny low-carbon bainite tissue, except irregular crystal boundary pinning magnetic domain wall movement, the more important thing is lattice defects a large amount of in the ferrite lath, as dislocation, subgrain boundaries etc. also seriously hinder magnetic domain wall movement, the electromagnetic performance of grievous injury soft magnetic structural steel; If soft magnetism
◆ structural steel and iron grain-size too thick (＞25 μ m), though can improve the electromagnetic performance of soft magnetic structural steel plate, the magneticflux-density under the downfield especially, its low-temperature impact toughness, the low-temperature impact toughness rapid deterioration of welded heat affecting zone especially.Therefore, the microstructure of soft magnetic structural steel plate should be
Even tiny equiaxed ferritic grain, the ferrite crystal grain chi Very little between 10 μ m～25 μ m.
Technical scheme of the present invention is: a kind of soft magnetic structural steel of resisting salt fog corrosion, and the weight percent of component is:
C：0.020％～0.040％
Si：1.40％～1.60％
Mn：0.40％～0.80％
P：≤0.015％
S：≤0.005％
Als：0.040％～0.060％
Cu：0.20％～0.50％
Ti：0.035％～0.055％
N：≤0.0035％
Ni：0.80％～1.20％
Ca or REM:0.001%～0.006%
All the other are iron and inevitably are mingled with.
And require Pcm≤0.20%
Pcm=wt%C+wt%Si/30+ (wt%Mn+wt%Cu+wt%Cr)/20+wt%Ni/60+wt%Mo/15+wt%V/10+5wt%B wherein
Weight proportion to the component of soft magnetic structural steel plate is further optimized, and the ratio range that obtains after preferred is:
C：0.025％～0.035％
Si：1.45％～1.55％
Mn：0.55％～0.65％
P：≤0.013％
S：≤0.003％
Als：0.040％～0.060％
Cu：0.30％～0.40％
Ti：0.040％～0.050％
N：≤0.0030％
Ni：0.90％～1.10％
Ca or REM:0.002%～0.005%
All the other are iron and inevitably are mingled with.
And require Pcm≤0.18%
Pcm=wt%C+wt%Si/30+ (wt%Mn+wt%Cu+wt%Cr)/20+wt%Ni/60+wt%Mo/15+wt%V/10+5wt%B wherein
Having extremely according to the present invention, the soft magnetic structural steel plate tissue of excellent low temperature impact toughness (below 30 ℃) is even tiny (10 μ m～25 μ m) equiaxed ferritic grain.
Casting technique of the present invention recommends to adopt continuous casting process, continuous casting process emphasis control pouring temperature and solidification of molten steel speed, and pouring temperature≤1560 ℃ are preferably between 1525 ℃～1550 ℃, and the low temperature teeming practice is relatively good.Molten steel does not take place under the condition of crackle from liquidus line to the solidus curve setting rate at strand, and setting rate is fast as far as possible.
Adopt the heating of very low temperature slab, slab heating temperature is controlled between 1000 ℃～1150 ℃, is preferably between 1050 ℃～1100 ℃, guarantees that original slab autstenitic grain size is even and tiny.In the perfect recrystallization temperature range, big rolling pass draft carries out quick continuous rolling, guarantees deformable metal generation perfect recrystallization, rolling pass draft 〉=15% for this reason, best 〉=20%, the total draft of hot rolling 〉=70%, best 〉=80%; The control finishing temperature is at Ar
3More than+30 ℃ of points, Ar wherein
3(℃)=910-310[%C]-80[%Mn]-20[%Cu]-15[%Cr]-55[%Ni]-80[%Mo]-0.35 (t-8), t is thickness of slab (mm).Should control shortly as far as possible from rolling the end to the biography time of putting beginning to quicken to cool off, strive being controlled in 30 seconds, preferably be controlled in 15 seconds, and when particularly importantly quickening the cooling beginning, steel billet temperature must be at Ar
3More than the point, with 〉=10 ℃/s, best 〉=20 ℃/s speed of cooling is cooled to below 500 ℃, is preferably between 300 ℃～500 ℃, and stacking slow cooling or burial pit slow cooling are to room temperature then; Perhaps roll back direct quenching (DQ-DirectQuenching) and stop temperature (QST-Quenching Stop Temperature) to quenching, QST also is controlled at below 500 ℃, be preferably between 300 ℃～500 ℃, after then about stacking slow cooling or burial pit slow cooling to 200 ℃, natural air cooling is to room temperature.The purpose that adopts stacking slow cooling or burial pit slow cooling is to eliminate should quicken to cool off in the inner internal stress that forms of steel plate, improves electromagnetic performance, and slowly speed of cooling is controlled at≤60 ℃/h.
The invention has the beneficial effects as follows: composition of the present invention is reasonable in design, realized the organic unity of the high strength, high tenacity of soft magnetic structural steel plate, good weldability and good electromagnetic property, the more important thing is to have high resisting salt fog corrosion characteristic, be specially adapted to the coastland of high salt fog.Promptly adopt ultralow C, 1.40%～1.60%Si content, low Mn, the high Ni alloying of Cu+, the Ti of adding 0.035%～0.055%, control N content is lower than 0.0035%, and technique means such as employing Ca or rare earth elements RE M processing, optimize recrystallize controlled rolling and accelerated cooling process " RCR+ACC or RCR+IDQ (InterruptedDirect Quenching) " and follow-up retarded cooling process, the grain-size that makes the finished product soft magnetic structural steel plate is at 10～25 μ m, obtain excellent mechanical property, electromagnetic performance and weldability the more important thing is that having solved existing soft magnetic structural steel plate salt fog resistance (mainly is anti-Cl
-Ion etching) problem of wretched insufficiency is developed the soft magnetic structural steel plate that suits in coastal high salt fog area use; Simultaneously, this soft magnetic structural steel plate also has good low-temperature impact toughness, guarantee the security of soft magnetic structural steel plate, simplified production technique, reduced production cost, further expanded the composition design system of soft magnetic structural steel in severe cold area (below 30 ℃) use.
Description of drawings
Accompanying drawing is the embodiment of the invention 3 soft magnetic structural steel microstructure metallographs
Embodiment
Embodiment: soft magnetic structural steel board manufacturing process of the present invention is as follows: the laboratory vacuum induction furnace smelting, after molten steel component reaches target component, begin casting immediately, and the pouring temperature of molten steel is 1525 ℃～1550 ℃.Slab is soaking time=thickness of slab (mm) * (0.5～1.0) min/mm in process furnace, soaking temperature is 1050 ℃～1100 ℃, 9 passage rolling technologys are adopted in hot rolling, accumulative total draft 70%～90%, finishing temperature is 800 ℃～850 ℃, finish to gauge finish and begin to quicken to cool off between the biography time of putting be 15s～30s, the surface temperature of steel ingot is more than 800 ℃ when beginning to quicken to cool off, quicken speed of cooling and be 10 ℃/s～30 ℃/s, stopping cold temperature is 500 ℃～600 ℃, (slow speed of cooling≤1 ℃/min), nature is to room temperature then to slowly cool to 300 ℃ subsequently.
5 comparative examples of the present invention and 4 embodiment A, B, C, D compositions see Table 1, and the mechanical property contrast sees Table 2, is containing salts contg 6.0mg/m
2D (milligram/rice
2* sky) the corrosion weight loss speed in the atmosphere sees Table 3.
Table 1 chemical ingredients
Embodiment 3 is that accompanying drawing is seen in the metallographic structure of C of the present invention
The contrast of table 2 mechanical property
| The steel sample | The steel sample | σ a (MPa) | σ b (MPa) | δ (％) | ρ (μΩm) | Mother metal transverse impact merit (J) | Mother metal impact of collision merit (J) | Grain-size (μ m) | B3 (T) | B40 (T) | Welding heat simulated HAZ ballistic work (J) |
| Germany | Comparative example | 363 | 529 | 31 | 0.382 | 32(0℃) | 58(0℃) | 45 | 0.62 | 1.57 | / |
| Baosteel 2001 | Baosteel 2001 | 370 | 508 | 33 | 0.380 | 144(0℃) | 208(0℃) | 18 | 0.95 | 1.61 | 16.7(0℃) |
| Baosteel 2002 | Baosteel 2002 | 380 | 485 | 35 | 0.420 | 174(-20℃) | 278(-20℃) | 28 | 1.20 | 1.66 | 61(-20℃) |
| Baosteel 2003 | Baosteel 2003 | 388 | 505 | 33.7 | 0.413 | 270(-30℃) | 222(-30℃) | 15 | 1.19 | 1.63 | 24(-30℃) 11.7(-40℃) |
| Baosteel 2004 | Baosteel 2004 | 402 | 514 | 35 | 0.396 | 158(-40℃) | 150(-40℃) | 19 | 1.15 | 1.65 | 49(-40℃) |
| A of the present invention | A of the present invention | 387 | 523 | 34.2 | 0.411 | 166(-40℃) | 178(-40℃) | 21 | 1.13 | 1.64 | 76(-40℃) |
| B of the present invention | B of the present invention | 396 | 526 | 35.3 | 0.399 | 172(-40℃) | 186(-40℃) | 20 | 1.10 | 1.63 | 92(-40℃) |
| C of the present invention | C of the present invention | 393 | 537 | 36.1 | 0.403 | 152(-40℃) | 205(-40℃) | 23 | 1.10 | 1.66 | 85(-40℃) |
| D of the present invention | D of the present invention | 381 | 518 | 35.3 | 0.399 | 168(-40℃) | 167(-40℃) | 20 | 1.10 | 1.63 | 81(-40℃) |
◆ welding heat analog parameter: single loop, 1350 ℃ of simulated peak temperature, t
8/5=50 seconds.
Table 3 is containing salts contg 6.0mg/m
2D (milligram/rice
2* sky) the corrosion weight loss speed in the atmosphere
| The steel sample | Corrosion weight loss speed g/ (m 2hr) | Relative erosion rate (%) |
| Q235 | 1.76 | 100 |
| Germany | 1.28 | 73 |
| Baosteel 2001 | 1.10 | 62 |
| Baosteel 2002 | 1.11 | 62 |
| Baosteel 2003 | 1.06 | 60 |
| Baosteel 2004 | 1.08 | 61 |
| A of the present invention | 0.66 | 0.375 |
| B of the present invention | 0.63 | 0.358 |
| C of the present invention | 0.69 | 0.392 |
| D of the present invention | 0.65 | 0.369 |
Claims (7)
1, a kind of soft magnetic structural steel of resisting salt fog corrosion, the weight percent of component is:
C：0.020％～0.040％
Si：1.40％～1.60％
Mn：0.40％～0.80％
P：≤0.015％
S：≤0.005％
Als：0.040％～0.060％
Cu：0.20％～0.50％
Ti：0.035％～0.055％
N：≤0.0035％
Ni：0.80％～1.20％
Ca or REM:0.001%～0.006%
All the other are iron and inevitably are mingled with.
2, the soft magnetic structural steel of resisting salt fog corrosion according to claim 1 is characterized in that: Pcm≤0.20%, wherein Pcm=wt%C+wt%Si/30+ (wt%Mn+wt%Cu+wt%Cr)/20+wt%Ni/60+wt%Mo/15+wt%V/10+5wt%B.
3, the soft magnetic structural steel of resisting salt fog corrosion according to claim 1 is characterized in that: the weight percent of component is: C:0.025%～0.035%
Si：1.45％～1.55％
Mn：0.55％～0.65％
P：≤0.013％
S：≤0.003％
Als：0.040％～0.060％
Cu：0.30％～0.40％
Ti：0.040％～0.050％
N：≤0.0030％
Ni：0.90％～1.10％
Ca or REM:0.002%～0.005%
All the other are iron and inevitably are mingled with.
4, the soft magnetic structural steel of resisting salt fog corrosion according to claim 3 is characterized in that: Pcm≤0.18%,
Pcm=wt%C+wt%Si/30+ (wt%Mn+wt%Cu+wt%Cr)/20+wt%Ni/60+wt%Mo/15+wt%V/10+5wt%B wherein.
5, the soft magnetic structural steel of resisting salt fog corrosion according to claim 1 is characterized in that: the microstructure of soft magnetic structural steel should be evenly tiny equiaxed ferritic grain, and ferrite grain size is between 10 μ m～25 μ m.
6, the manufacture method of the soft magnetic structural steel of the described resisting salt fog corrosion of claim 1, adopt continuous casting process, carry out the recrystallize controlled rolling then and quicken cooling or recrystallize controlled rolling and interruption direct quenching and follow-up retarded cooling process, it is characterized in that: pouring temperature is 1525 ℃～1550 ℃, slab heating temperature is controlled between 1000 ℃～1150 ℃, rolling pass draft 〉=15%, the total draft of hot rolling 〉=70%, the control finishing temperature is at Ar
3More than+30 ℃ of points, Ar wherein
3(℃)=910-310[%C]-80[%Mn]-20[%Cu]-15[%Cr]-55[%Ni]-80[%Mo]-0.35 (t-8), t is thickness of slab mm; Be controlled in 30 seconds to the biography time of putting beginning to quicken to cool off from rolling the end, when quickening the cooling beginning, steel billet temperature must be at Ar
3More than the point, be cooled to below 500 ℃ with 〉=10 ℃/s speed of cooling, stacking slow cooling or burial pit slow cooling are to room temperature then; Perhaps roll back direct quenching and stop temperature to quenching, QST is controlled at below 500 ℃, and after stacking slow cooling or the burial pit slow cooling to 200 ℃, natural air cooling is to room temperature then, and slowly speed of cooling is controlled at≤60 ℃/h.
7, the manufacture method of the soft magnetic structural steel of resisting salt fog corrosion according to claim 6, it is characterized in that: slab heating temperature is 1050 ℃～1100 ℃, rolling pass draft 〉=20%, the total draft of hot rolling 〉=80%, be controlled in 15 seconds to the biography time of putting beginning to quicken to cool off from rolling the end, speed of cooling 〉=20 ℃/s are cooled to 300 ℃～500 ℃, and QST is controlled between 300 ℃～500 ℃.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1099900A (en) * | 1993-09-01 | 1995-03-08 | 日本钢管株式会社 | Soft magnetic steel and method therefor |
| US5601664A (en) * | 1994-10-11 | 1997-02-11 | Crs Holdings, Inc. | Corrosion-resistant magnetic material |
| CN1072274C (en) * | 1996-08-10 | 2001-10-03 | 蒂森钢铁股份公司 | High duty soft magnetic steel suitable for welding and its use in parts of magnetic levitational railways |
| CN1169993C (en) * | 2001-09-29 | 2004-10-06 | 宝山钢铁股份有限公司 | High performance soft steel magnet for magnetic suspension train |
-
2005
- 2005-06-30 CN CNB2005100273122A patent/CN100352963C/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1099900A (en) * | 1993-09-01 | 1995-03-08 | 日本钢管株式会社 | Soft magnetic steel and method therefor |
| US5601664A (en) * | 1994-10-11 | 1997-02-11 | Crs Holdings, Inc. | Corrosion-resistant magnetic material |
| CN1072274C (en) * | 1996-08-10 | 2001-10-03 | 蒂森钢铁股份公司 | High duty soft magnetic steel suitable for welding and its use in parts of magnetic levitational railways |
| CN1169993C (en) * | 2001-09-29 | 2004-10-06 | 宝山钢铁股份有限公司 | High performance soft steel magnet for magnetic suspension train |
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