A kind of centrifugal composite modified indefinite chilled cast iron roller and preparation method thereof
Technical field
The present invention is all kinds of rolling mill hot rolls and manufacture method thereof, and particularly a kind of centrifugal composite modified indefinite chilled cast iron roller and preparation method thereof belongs to technical field of steel rolling.
Background technology
Roll is the main consumption spare part during steel rolling is produced, and roll quality is directly connected to steel rolling productivity, stocking surface quality and stocking production cost.The roll material of widespread use at present mainly contains high-chromium iron-cast roller, high-speed steel roll and infinitely chilled ductile cast iron roll, and wherein valuable alloy content is many in the high-speed steel roll, the production cost height; High-chromium iron-cast roller need carry out quench hot to be handled, and the production cycle is long, the energy consumption height.The infinitely chilled ductile cast iron roll does not need pyroprocessing, and production technique is simple, low production cost, widespread use in steel rolling is produced.The infinitely chilled ductile cast iron roll material is between cold hard cast-iron and grey cast iron, compare with cold hard cast-iron, silicon content is higher in the molten iron (contains 0.7~1.6%Si), therefore in the infinitely chilled ductile cast iron roller body working lining matrix except that contain with white cast iron in the carbide and ledeburite of close quantity, also have equally distributed graphite.Also usually add the alloying element such as Cr, Ni, Mo of different content in the infinitely chilled ductile cast iron roll, along with the increase of Cr, Ni, Mo content, its case depth increases greatly.Contain more carbide in the infinitely chilled ductile cast iron roller body matrix, have wear resistance preferably; In addition, equally distributed a small amount of tiny graphite has played the effect of lax mechanical stress in matrix, helps alleviating the defective of peeling off on body of roll top layer; Simultaneously, itself has good heat-conducting graphite, and in rolling process, when roller surface was subjected to thermal shocking, graphite played the buffering thermal stresses, helps preventing the generation of thermal crack.In addition, body surface forms tiny hole because graphite comes off, and improves the performance of nipping of roll.
Infinitely chilled ductile cast iron is because its hardness height, hot-cracking resistance that the hardness drop is little and good, and its thermal treatment process is simple in addition, has obtained using widely in the roll manufacturing.Generally use the infinitely chilled ductile cast iron roll on the countries in the world hot continuous mill finish rolling back segment finished frame, even the finish rolling leading portion still uses the infinitely chilled ductile cast iron roll always.In order to improve the performance of infinitely chilled ductile cast iron roll, developed modified version infinitely chilled ductile cast iron roll [Pereira W A abroad, Linhares J C, Azevedo S J, Carvalho M A, Filho C SP, Xavier R R and Silva C H.CSN ' s strategy for roll performance improvement inthe hot strip mill.43rd MWSP Conference Proceedings, ISS, 2001,39:673~681 and Andersson M, Finnstrom R and Nylen T.Introduction of enhanced indefinite chilland high speed steel rolls in European hot strip mills.Ironmaking and Steelmaking, 2004,31 (5): 383~388].Foreign patent EP871784-A, WO9639544-A and WO9639544-A1 disclose a kind of infinitely chilled ductile cast iron roll that contains niobium, containing C 2.5-4.0%, Ni4.2-4.6%, Mo 0.3-0.5%, Cr 1.5-2.0% is in the infinitely chilled ductile cast iron roll of Si 0.7-1.2% and Mn 0.7-1.0%, add 0.3-6.0% Nb, can improve roller surface hardness, improve wear resistance, only add niobium breaker roll intensity and flexible and improve not obvious.Chinese invention patent CN85102602 discloses technology of infiltration casting for making cast iron chilled rolls, and this invention is selected for use the insensitive soft molten iron of spoken parts in traditional operas, contains Te coating in the cold type inner wall spraying.The Te fusing of cast back also is carried, diffuses into the roll surface certain depth.Adjustment contains the Te amount then can adjust chill depth and fiber crops mouthful size, and the Te that the while roll surface contains 100~600ppm can promote the abundant whitening of roll surface, and roll surface hardness is brought up to HS72-78.This method is applicable to rubber machine roll, can significantly improve supporting capacity, the wear resistance of roll, and this invention spoken parts in traditional operas wearing layer is more shallow, is difficult to promote the use of in technical field of steel rolling.Chinese invention patent CN1068149 discloses vanadium titanium unlimited chilled ductile iron roll and castmethod, it is characterized in that not containing alloying elements such as Ni, Cr, Mo, Cu in the chemical ingredients, is spheroidal graphite cast iron from body of roll working lining to core.During casting, the mixed nodulizer that has used rare earth magnesium and iron magnesium nodulizer to form has adopted annealing process in low dose of nucleating agent method and the type.Roll cost that this invention is produced is low, and the intensity height is difficult for roll breakage during rolling stock, and the roller trough rim is difficult for falling piece, be used on first and second frame of middle-size and small-size rolling mill to replace cast steel roll, and its life-span improves more than 20% than cast steel roll.Do not contain Ni, the Cr, the alloying elements such as Mo, Cu that improve hardening capacity and wear resistance in this invention, quench-hardened case is more shallow, and wear resistance is good not as the unlimited chilled ductile iron roll that contains alloying elements such as Ni, Cr, Mo, Cu.Chinese invention patent CN1598030 discloses improved roll nickel chromium triangle molybdenum infinitely chilled ductile cast iron and composite roll, it is characterized in that containing 2.90~3.70%C, 0.60~1.20%Si, 0.4~1.2%Mn, 3.01~5.00%Ni, 1.00~2.00%Cr, 0.20~0.60%Mo, in the nickel chromium triangle molybdenum infinitely chilled ductile cast iron roll that surplus Fe forms, add 0.03~0.1%B and 0.2~1.5%Nb, the wear resistance of material and heat resistanceheat resistant crack performance are significantly improved.But after partly boron dissolves in matrix, increase matrix fragility, the aggravation roll lost efficacy.
Summary of the invention
The purpose of this invention is to provide a kind of centrifugal composite modified indefinite chilled cast iron roller and preparation method thereof.The present invention adopts a kind of modified version infinitely chilled ductile cast iron to make the outer body of roll of composite roll, makes the internal layer roller core with spheroidal graphite cast iron or meehanite cast iron, and adopts centrifugal composite casting method castable.Its principal feature is in nickel chromium triangle aluminium infinitely chilled ductile cast iron, adds amount of copper, is used to improve roll hardening capacity, improves roll strength and toughness, in addition, also adds a small amount of niobium, vanadium and titanium in the skin of the roll, and purpose is for refinement roll solidified structure.Skin of the roll adopts copper-magnesium alloy and Yttrium base rare earth magnesium alloy compound spheroidizing to handle, and also adds an amount of star antimony to eliminate lopsided graphite, has obviously improved the nodularization effect of roll, and roll mechanical property and wear resistance are obviously improved.
Purpose of the present invention can realize by following measure:
The outer field chemical composition of centrifugal composite modified indefinite chilled cast iron roller of the present invention is (weight %): 3.2-3.8C, 3.8-4.5Ni, 1.2-1.8Cr, 0.2-0.4Mo, 0.2-0.5Cu, 1.0-1.8Si,<0.8Mn, 0.10-0.30Nb, 0.05-0.20V, 0.05-0.20Ti, 0.04-0.07Mg, 0.02-0.05Y, 0.01-0.03Sb, all the other are Fe and inevitable trace impurity.
But roll electric furnace of the present invention production, its manufacturing technology steps is:
1. with ordinary scrap steel, the pig iron, ferrochrome, ferrosilicon, molybdenum-iron, nickel plate and the fusing of copper coin Hybrid Heating.
2. the stokehold is adjusted to branch and temperature is risen to 1450-1500 ℃ after qualified, adds reductor aluminium, after skimming ferro-niobium, ferrotianium and vanadium iron is added in the stove.
3. imbedding in the casting ladle with the above-mentioned raw materials mass ratio is the copper-magnesium alloy of 0.8%-1.2% Yttrium base rare earth magnesium nodulizer and 0.3%-0.5%, the compacting of loam cake iron filings.Adopt dam-type to pour the method spheroidizing, pour 0.5%-1.0% ferrosilicon inoculation with stream simultaneously, add an amount of star antimony, tap a blast furnace and close and cover plant ash when wrapping.
4. pour into a mould outer infinitely chilled ductile cast iron on whizzer, outer molten iron pouring temperature is 1350-1400 ℃;
5. after outer cast finishes, when the internal surface temperature of skin of the roll is 1250-1280 ℃, continue casting internal layer roller core molten iron, the roller core material is spheroidal graphite cast iron or meehanite cast iron.
6. composite roll carries out stress relief annealing processing 10-15 hour at 450-530 ℃.
The performance of centrifugal composite casting modified version infinitely chilled ductile cast iron roll and its composition and melting technology have direct relation, and roll chemical ingredients of the present invention is to determine like this:
C:C influences centrifugal composite modified indefinite chilled cast iron roller hardness and flexible principal element, when its content is high, carbide quantity is many in the tissue, the matrix hardness height, and wear resistance is good, but too high levels, carbide quantity is too many and thick, and toughness is descended, and is prone to be full of cracks during roll uses even produces to peel off, reduce roll work-ing life on the contrary, so C content is advisable with 3.2-3.8%.
Ni: add nickel in the infinitely chilled ductile cast iron roll, can obviously improve roll hardening capacity, add-on is too much, and retained austenite is too many in the roll tissue, is unfavorable for improving roll hardness and improves the roll wear resistance, and suitable Ni add-on is 3.8-4.5%.
Cr: the chromium that in the infinitely chilled ductile cast iron roll, adds, part enters carbide, improves carbide hardness, part enters matrix, improves hardening capacity, and chromium adds too much in the infinitely chilled ductile cast iron roll, roll fragility is big, is prone to crackle in the use and peels off, and appropriate C r add-on is 1.2-1.8%.
Mo: in the infinitely chilled ductile cast iron roll, add a small amount of molybdenum, can thinning solidification structure, improve roll strength and toughness, add molybdenum element in the roll, can also improve hardening capacity, molybdenum can also improve the anti-temper resistance of roll material, improve the roll high-temperature behavior, but molybdenum is expensive element, add-on is too much, to increase the roll production cost, suitable Mo add-on is 0.2-0.4%.
Cu: add amount of copper in the infinitely chilled ductile cast iron roll, can improve roll hardening capacity, appropriate C u add-on is 0.2-0.5%.
Si: silicon is to promote graphite element, adds proper amount of silicon in the infinitely chilled ductile cast iron roll, easily promotes separating out of graphite, help improving the thermal fatigue resistance of roll, add-on is too much, and graphite is too many and thick, damage the intensity and the toughness of roll on the contrary, suitable Si add-on is 1.0-1.8%.
Mn: add too many manganese in the infinitely chilled ductile cast iron roll, it is thick easily to impel roll to organize, and therefore the intensity and the toughness of infringement roll are controlled at Mn content below 0.8%.
Nb, V and Ti: niobium, vanadium and titanium are the strong carbide forming elements, the carbide fusing point height, the good stability that form, in the infinitely chilled ductile cast iron roll, add a small amount of niobium, vanadium and titanium, easily impel the solidified structure refinement, also help the form and the distribution that improve carbide, can obviously improve the intensity and the toughness of roll, improve the roll wear resistance.Add-on is too much, and carbide increases and alligatoring, damages the intensity and the toughness of roll on the contrary.Suitable Nb add-on is 0.10-0.30%, and suitable V add-on is 0.05-0.20%, and suitable Ti add-on is 0.05-0.20%.
Mg and Y: add magnesium and yttrium at the infinitely chilled ductile cast iron roll, mainly be in order to obtain the globular graphite tissue, help improving the intensity and the toughness of roll, improve the roll thermal fatigue resistance, add Yttrium base rare earth, also have the effect of thinning solidification structure and purification roll, can prolong roll work-ing life, add-on is too much, and the roll chilling tendency is obvious, is unfavorable for improving the roll use properties.Suitable Mg add-on is 0.04-0.07%, and suitable Y add-on is 0.02-0.05%.
Sb: add an amount of star antimony to eliminate lopsided graphite at the infinitely chilled ductile cast iron roll, improve roll mechanical property and wear resistance, suitable Sb add-on is 0.01-0.03%.
Inevitably trace impurity is to bring in the raw material, and P and S are wherein arranged, and all is harmful elements, and intensity, toughness and wear resistance in order to guarantee roll are controlled at P content below 0.06%, and S content is controlled at below 0.03%.
The present invention compared with prior art has following characteristics:
(1) body of roll of modified version infinitely chilled ductile cast iron roll of the present invention is organized tinyly, and distribution of carbides is even;
(2) carbide of modified version infinitely chilled ductile cast iron roll of the present invention is the distribution of suspension shape, and carbide size is less than 40 μ m;
(3) intensity of modified version infinitely chilled ductile cast iron roll of the present invention and hardness height, the roll surface uniformity of hardness is good, and roll radial stiffness drop is little, and toughness and wear resistance are good, and wherein bending strength is greater than 800MPa, and impelling strength is greater than 13J/cm
2, roll surface hardness is greater than 83Hs, and the roll surface difference of hardness is less than 1.5HS, from the hardness drop at roll surface 40mm place less than 3.0HS, hardness value from roll surface 40mm place surpasses 80HS, in the work-ing life on hot finisher, improves 32-37% than high nickel chromium triangle infinitely chilled ductile cast iron roll.
Description of drawings
Fig. 1 centrifugal composite modified indefinite chilled cast iron roller synoptic diagram.
Label among the figure is represented respectively: 1, skin of the roll, 2, the roll internal layer.
Embodiment
The present invention adopts centrifugal composite casting modified version infinitely chilled ductile cast iron roll, and the chemical ingredients of the body of roll (weight %) sees Table 1.
Table 1 modified version infinitely chilled ductile cast iron roll chemical composition (weight %)
Element |
C |
Ni |
Cr |
Mo |
Nb |
Si |
Cu |
Mn |
Composition |
3.2-3.8 |
3.8-4.5 |
1.2-1.8 |
0.2-0.4 |
0.10-0.30 |
1.0-1.8 |
0.2-0.5 |
<0.8 |
Element |
V |
Ti |
Mg |
Y |
Sb |
S |
P |
Fe |
Composition |
0.05-0.2 |
0.05-0.2 |
0.04-0.07 |
0.02-0.05 |
0.01-0.03 |
<0.03 |
<0.06 |
Surplus |
But roll electric furnace of the present invention production, its manufacturing technology steps is:
1. with ordinary scrap steel, the pig iron, ferrochrome, ferrosilicon, molybdenum-iron, nickel plate and the fusing of copper coin Hybrid Heating.
2. the stokehold is adjusted to branch and temperature is risen to 1450-1500 ℃ after qualified, adds reductor aluminium, after skimming ferro-niobium, ferrotianium and vanadium iron is added in the stove.
3. imbedding in the casting ladle with the above-mentioned raw materials mass ratio is the copper-magnesium alloy of 0.8%-1.2% Yttrium base rare earth magnesium nodulizer and 0.3%-0.5%, the compacting of loam cake iron filings.Adopt dam-type to pour the method spheroidizing, pour 0.5%-1.0% ferrosilicon inoculation with stream simultaneously, add an amount of star antimony, tap a blast furnace and close and cover plant ash when wrapping.
4. pour into a mould outer 1 infinitely chilled ductile cast iron on whizzer, outer 1 molten iron pouring temperature is 1350-1400 ℃;
5. after outer 1 cast finishes, when the internal surface temperature of skin of the roll 1 is 1250-1280 ℃, continue casting internal layer 2 roller core molten iron, roller core 2 materials are spheroidal graphite cast iron or meehanite cast iron.
6. composite roll carries out the stress relief annealing processing at 450-530 ℃.
The invention will be further described below in conjunction with embodiment:
Embodiment 1:
The centrifugal composite modified indefinite chilled cast iron roller of present embodiment preparation, with the medium-frequency induction furnace production of 750 kg capacity, its manufacturing technology steps is:
1. with ordinary scrap steel, the pig iron, ferrochrome, ferrosilicon, molybdenum-iron, nickel plate and the fusing of copper coin Hybrid Heating.
2. the stokehold is adjusted to branch and temperature is risen to 1482 ℃ after qualified, adds reductor aluminium, after skimming ferro-niobium, ferrotianium and vanadium iron is added in the stove.
3. imbedding in the casting ladle with the above-mentioned raw materials mass ratio is the copper-magnesium alloy of 1.03% Yttrium base rare earth magnesium nodulizer and 0.38%, the compacting of loam cake iron filings.Adopt dam-type to pour the method spheroidizing, pour 0.85% ferrosilicon inoculation with stream simultaneously, add an amount of star antimony, tap a blast furnace and close and cover plant ash when wrapping.
4. pour into a mould outer 1 infinitely chilled ductile cast iron on whizzer, outer 1 molten iron pouring temperature is 1374 ℃;
5. after outer 1 cast finishes, when the internal surface temperature of skin of the roll 1 is 1272 ℃, continue casting internal layer 2 roller core molten iron, roller core 2 materials are spheroidal graphite cast iron.
6. composite roll carries out the stress relief annealing processing at 480 ℃, annealing soaking time 10 hours.
The skin of the roll composition sees Table 2, and the roll mechanical property sees Table 3.
Table 2 modified version infinitely chilled ductile cast iron roll chemical composition (weight %)
Element |
C |
Ni |
Cr |
Mo |
Cu |
Si |
Mn |
Nb |
Composition |
3.47 |
4.14 |
1.56 |
0.31 |
0.40 |
1.47 |
0.68 |
0.18 |
Element |
V |
Ti |
Mg |
Y |
Sb |
S |
P |
Fe |
Composition |
0.09 |
0.13 |
0.051 |
0.038 |
0.019 |
0.016 |
0.045 |
Surplus |
Table 3 roll mechanical property
Roll hardness HS |
Roll surface difference of hardness HS |
Apart from the hardness value at roll surface 40mm place, HS |
Bending strength MPa |
Impelling strength J/cm
2 |
83.6 |
1.2 |
80.9 |
824.5 |
14.2 |
Embodiment 2:
The centrifugal composite modified indefinite chilled cast iron roller of present embodiment preparation, with the medium-frequency induction furnace production of 1000 kg capacity, its manufacturing technology steps is:
1. with ordinary scrap steel, the pig iron, ferrochrome, ferrosilicon, molybdenum-iron, nickel plate and the fusing of copper coin Hybrid Heating.
2. the stokehold is adjusted to branch and temperature is risen to 1465 ℃ after qualified, adds reductor aluminium, after skimming ferro-niobium, ferrotianium and vanadium iron is added in the stove.
3. imbedding in the casting ladle with the above-mentioned raw materials mass ratio is the copper-magnesium alloy of 0.90% Yttrium base rare earth magnesium nodulizer and 0.45%, the compacting of loam cake iron filings.Adopt dam-type to pour the method spheroidizing, pour 0.66% ferrosilicon inoculation with stream simultaneously, add an amount of star antimony, tap a blast furnace and close and cover plant ash when wrapping.
4. pour into a mould outer 1 infinitely chilled ductile cast iron on whizzer, outer 1 molten iron pouring temperature is 1358 ℃;
5. after outer 1 cast finishes, when the internal surface temperature of skin of the roll 1 is 1261 ℃, continue casting internal layer 2 roller core molten iron, roller core 2 materials are meehanite cast irons.
6. composite roll carries out the stress relief annealing processing at 460 ℃, annealing soaking time 15 hours.
The skin of the roll composition sees Table 4, and the roll mechanical property sees Table 5.
Table 4 modified version infinitely chilled ductile cast iron roll chemical composition (weight %)
Element |
C |
Ni |
Cr |
Mo |
Cu |
Si |
Mn |
Nb |
Composition |
3.55 |
3.89 |
1.71 |
0.36 |
0.43 |
1.35 |
0.70 |
0.24 |
Element |
V |
Ti |
Mg |
Y |
Sb |
S |
P |
Fe |
Composition |
0.11 |
0.07 |
0.058 |
0.033 |
0.022 |
0.019 |
0.046 |
All the other |
Table 5 roll mechanical property
Roll hardness HS |
Roll surface difference of hardness HS |
Apart from the hardness value at roll surface 40mm place, HS |
Bending strength MPa |
Impelling strength J/cm2 |
83.3 |
1.3 |
80.5 |
818.6 |
13.7 |
Embodiment 3:
The centrifugal composite modified indefinite chilled cast iron roller of present embodiment preparation, with the medium-frequency induction furnace production of 1500 kg capacity, its manufacturing technology steps is:
1. with ordinary scrap steel, the pig iron, ferrochrome, ferrosilicon, molybdenum-iron, nickel plate and the fusing of copper coin Hybrid Heating.
2. the stokehold is adjusted to branch and temperature is risen to 1498 ℃ after qualified, adds reductor aluminium, after skimming ferro-niobium, ferrotianium and vanadium iron is added in the stove.
3. imbedding in the casting ladle with the above-mentioned raw materials mass ratio is the copper-magnesium alloy of 0.80% Yttrium base rare earth magnesium nodulizer and 0.50%, the compacting of loam cake iron filings.Adopt dam-type to pour the method spheroidizing, pour 1.00% ferrosilicon inoculation with stream simultaneously, add an amount of star antimony, tap a blast furnace and close and cover plant ash when wrapping.
4. pour into a mould outer 1 infinitely chilled ductile cast iron on whizzer, outer 1 molten iron pouring temperature is 1391 ℃;
5. after outer 1 cast finishes, when the internal surface temperature of skin of the roll 1 is 1277 ℃, continue casting internal layer 2 roller core molten iron, roller core 2 materials are spheroidal graphite cast iron.
6. composite roll carries out the stress relief annealing processing at 525 ℃, annealing soaking time 12 hours.
The skin of the roll composition sees Table 6, and the roll mechanical property sees Table 7.
Table 6 modified version infinitely chilled ductile cast iron roll chemical composition (weight %)
Element |
C |
Ni |
Cr |
Mo |
Cu |
Si |
Mn |
Nb |
Composition |
3.20 |
4.43 |
1.29 |
0.25 |
0.48 |
1.71 |
0.54 |
0.15 |
Element |
V |
Ti |
Mg |
Y |
Sb |
S |
P |
Fe |
Composition |
0.18 |
0.05 |
0.069 |
0.024 |
0.012 |
0.017 |
0.039 |
All the other |
Table 7 roll mechanical property
Roll hardness HS |
Roll surface difference of hardness HS |
Apart from the hardness value at roll surface 40mm place, HS |
Bending strength MPa |
Impelling strength J/cm
2 |
83.1 |
1.2 |
80.3 |
833.9 |
14.9 |
Get the roll of the present invention use of installing, the result is as follows:
Working conditions is the hot rolled strip finishing train of width 400mm, and the steel rolling amount of centrifugal composite modified indefinite chilled cast iron roller of the present invention improves 32-37% than high nickel chromium triangle infinitely chilled ductile cast iron roll
Roll of the present invention compared with prior art has the following advantages:
Roll strength of the present invention and hardness are high, toughness, uniformity of hardness and quenching degree are good, wearability and non-oxidizability are good, anti-chilling and shock heating performance is also fine, do not rupture in the use procedure, non-scale, do not chap, non-stick steel, serviceability obviously is better than high Ni-Cr infinite cold hardness cast iron roll, production technology is simple, do not need to carry out high-temperature heat treatment, production cost is low. Use roll of the present invention can significantly improve the rolling mill operating rate, reduce the stocking production cost, improve the stocking surface quality, have good economic and social benefit.