CN103938076A - Method for producing 500MPa-level door frame steel for forklift - Google Patents
Method for producing 500MPa-level door frame steel for forklift Download PDFInfo
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- CN103938076A CN103938076A CN201410169482.3A CN201410169482A CN103938076A CN 103938076 A CN103938076 A CN 103938076A CN 201410169482 A CN201410169482 A CN 201410169482A CN 103938076 A CN103938076 A CN 103938076A
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Abstract
The invention discloses a method for producing 500MPa-level door frame steel for a forklift. The method sequentially comprises the following steps: molten iron pre-desulfurization, converter smelting, LF refining, full-protection continuous casting, and rolling. The 500MPa-level door frame steel for the forklift comprises the following chemical components by weight percent: 0.24-0.30% of C, 0.15-0.30% of Si, 1.05-1.30% of Mn, no more than 0.025% of P, no more than 0.015% of S, 0.05-0.08% of V, and the balance being iron and inevitable impurities. The method mainly aims at improving the carbon content and reducing sulfur and phosphorus content, microalloying is performed by just vanadium, other elements are not added, controlled cooling after rolling is not needed, and heat treatment is avoided; the obtained steel is good in mechanical property, the average yield strength is 531MPa, the average tensile strength is 685MPa, the average ductility is 23.5%, the Brinell hardness is greater than 210, and the average impact power at 20 DEG C is 59J.
Description
Technical field
The invention belongs to metallurgical technology field, be specifically related to the production method of a kind of 500MPa level fork truck gantry-shaped steel.
Background technology
Fork truck is as the important equipment of logistics system, and its demand constantly increases.And as fork truck to the fork of goods get, the door frame that hoists of the operation such as lifting, stacking, piling, it is most important primary structure member, and door frame is to be all suspended on the drive axle in fork truck front, balance weight type front, get, promote and convey goods in operation pitching, centered by front driving axle, producing very large moment.Therefore improve the intensity of portal frame system, not only can make the security and stability of door frame greatly improve, can reduce portal frame system deadweight simultaneously, production material cost is reduced, significantly improve its its usage economy.
In recent years, in industry, conventional gantry-shaped steel of forklift has 335MPa, 400MPa, 420MPa and 440MPa equal strength rank, is to a certain degree meeting the manufacture demand of domestic fork truck.But for 3 tons and the following fork truck for exporting, the high 3 grades of door frames that hoist of many employings, for the consideration of fork truck security and stability, in industry, can select 420MPa and some deficiency of 440MPa intensity rank of gantry-shaped steel of forklift, therefore Forklift Industry is urgently developed the 500MPa level shaped steel product that is applicable to such fork truck.
Summary of the invention
For the deficiencies in the prior art, the object of the present invention is to provide the production method of a kind of 500MPa level fork truck gantry-shaped steel, the steel that the method obtains has high strength and good mechanical properties.
For achieving the above object, the present invention has adopted following technical scheme:
A production method for gantry-shaped steel for 500MPa level fork truck, comprises molten iron pre-desulfurization, converter smelting, LF refining, full guard continuous casting, rolling step successively, wherein:
In described molten iron pre-desulfurization step, after desulfurization, ensure that Sulfur Content in Hot Iron content is≤0.010wt%;
In described converter smelting step, adopt top and bottom combined blown converter smelting;
In described LF refinement step, in refining process, abundant stirringization slag, makes yellowish-white slag;
In described full guard continuous casting step, adopt the casting of submerged nozzle full guard;
In described rolling step, the soaking temperature of process furnace is 1200～1215 DEG C, finishing temperature is 880 DEG C in web central authorities, stocking naturally cools to 300-450 DEG C at cold bed, then carry out water-cooled, after below rolled piece temperature is down to 100 DEG C, sends into straightener and align, finally rolled piece is cut to dimensioning;
The 500MPa level fork truck that this production method obtains consists of the following composition by weight percentage with gantry-shaped steel: C0.24～0.30%, Si0.15～0.30%, Mn1.05～1.30%, P≤0.025%, S≤0.015%, V0.05～0.08%, all the other are iron and inevitable impurity.
The soaking temperature of controlling process furnace in rolling step of the present invention is 1200-1215 DEG C, can well make VN alloy fully dissolve, play the effect of crystal grain thinning, avoid occurring may causing coarse grains because Heating temperature is too high simultaneously, cause intensity not reach the situation of requirement, the soaking before this rolling has been played vital effect for the high strength that realizes carbon shaped steel in the present invention.
In aforesaid method, as a kind of preferred implementation, described 500MPa level fork truck consists of the following composition by weight percentage with gantry-shaped steel: C0.25～0.29%, Si0.20～0.30%, Mn1.15～1.25%, P≤0.025%, S≤0.015%, V0.065～0.075%, all the other are iron and inevitable impurity.
In aforesaid method, as a kind of preferred implementation, in converter smelting step, adopt the low rifle bit manipulation of the large quantity of slag, converting process slag charge adds in two batches, adds in the first batch 2/3 slag charge; Adopt silicomanganese, middle manganese, vanadium nitrogen to carry out alloying, the target value of molten steel interalloy element is by the intermediate value control of respective element scope; Adopt aluminium manganese-ferro deoxidation, add-on 1.5～2.0kg/t steel; In tapping process, add synthetic slag 8～10kg/t steel, evenly add successively silicomanganese, middle manganese, aluminium ferromanganese, VN alloy, molten steel to go out to 3/4 o'clock to add when molten steel goes out to 1/4 time, alloy is aimed at steel stream and is impacted and go to add.In converter steelmaking process, adopt aluminium manganese-ferro deoxidation, in molten steel, acid-soluble aluminium reaches 0.03%～0.05wt%, and deoxidizing capacity is much larger than reductors such as silicon, carbon, manganese, and steel water oxygen is almost all transformed into Al
2o
3, add and can effectively reduce on a small quantity the oxygen level in molten steel, reduce oxide inclusion in steel, improve Cleanliness of Molten Steel, improve the over-all properties of product.
In aforesaid method, as a kind of preferred implementation, in described LF refinement step, also comprise that the omnidistance argon bottom-blowing of refining process stirs, the refining later stage feeds the pure calcium core-spun yarn of real core more than keeping the little argon gas stirring of top of the slag fine motion 10min before departures, feed quantity is 120～150m/ stove; Wherein, the little argon gas of described top of the slag fine motion refers to that argon flow amount is 50～150NL/min.In the present invention, adopt and feed the pure calcium core-spun yarn of real core, the recovery rate of calcium is high, line feeding length is short, the line feeding time is short, molten steel temperature drop is few, such as compared to iron calcium line, the recovery rate of calcium improves 30%, line feeding length reduces 50%, line feeding time shorten 2～3min, molten steel temperature drop reduces 3～5 DEG C, can reach deoxidation, desulfurization, makes nonmetal inclusion sex change and remove the good metallurgical effects such as hazardous trace elements.
In aforesaid method; as a kind of preferred implementation; in described full guard continuous casting step; use stopper tundish; use the cast of submerged nozzle full guard; wherein; two cold employings are weak cold, and crystallizer adopts non-sinusoidal oscillation, and liquidus temperature is 1509 DEG C; tundish superheating temperature is by 20～30 DEG C of controls; middle bag the first furnace temperature is controlled at 1530～1535 DEG C, and even watering heat is controlled at 1525～1533 DEG C, and continuous caster is that 6 machines 6 flow; casting blank specification is 165mm × 200mm, and pulling rate is 1.0～1.3m/min.The stopper control mechanism that tundish of the present invention adopts, can effectively control casting stream, improves continuous casting steel liquid level stabilizing, reduces casting blank defect, and then enhances product performance.
The NM operation of the present invention, is this area routine techniques.
Compared with prior art, the present invention has following beneficial effect: the present invention is mainly for the fork truck problem of gantry-shaped steel in composition, smelting and the operation of rolling, the production method of a kind of 500MPa level fork truck gantry-shaped steel is provided, the method is by improving carbon content, reduce sulphur, phosphorus content, microalloying mainly adopts vanadium, does not add other element, does not control cold and do not need to heat-treat after rolling.P of the present invention, S content are low, microalloy only adopts V, are ensureing that product has under the prerequisite of excellent mechanical performances, has realized low cost production.Steel mechanical property of the present invention is good, yield strength average out to 531MPa, and tensile strength average out to 685MPa, unit elongation average out to 23.5%, Brinell hardness is greater than 210,20 DEG C of average 59J of ballistic work.
Embodiment
Below by specific embodiment, the present invention is described in detail, but the present invention is not limited to this.
The production method of embodiment of the present invention 1-3 comprises molten iron pre-desulfurization, converter smelting (following examples adopt 80 tons of top and bottom combined blown converter smeltings), LF refining, full guard continuous casting, rolling (following examples adopt the rolling of 1-3 milling train layout pattern production line) successively, may be summarized to be:
1) molten iron, to desulfurization station, ensures after desulfurization that the sulphur content in molten iron is≤0.010wt%.
2) converter smelting: by the low rifle bit manipulation of the large quantity of slag, converting process, slag charge (adds in the first batch 2/3 slag charge) in two batches and adds, omnidistance bitsization are good, change is saturating.Adopt silicomanganese, middle manganese, vanadium nitrogen carries out alloying, requirement alloy is clean, dry, the target value of molten steel interalloy element is by the intermediate value control of respective element scope, adopt aluminium manganese-ferro deoxidation, add-on 1.5～2.0kg/t steel, in tapping process, add synthetic slag 8～10kg/t steel, when molten steel goes out to 1/4 time successively, evenly add silicomanganese, middle manganese, aluminium ferromanganese, VN alloy, molten steel goes out to 3/4 o'clock to add, alloy is aimed at steel stream impact zone and is added, those skilled in the art can select suitable compound or composition as synthetic slag according to actual needs, as long as component content meets the requirements.
3) LF refining: abundant stirringization slag in refining process, make yellowish-white slag, omnidistance argon bottom-blowing stirs, can according to circumstances suitably heighten argon pressure early stage, more than the little argon gas of refining later stage maintenance top of the slag fine motion stirs 10min, the pure calcium core-spun yarn of the feeding real core of feeding before departures, the pure calcium core-spun yarn feed quantity of real core is 120～150m/ stove.Wherein, the little argon gas amount of described top of the slag fine motion refers to that argon flow amount is 50～150NL/min.
4) continuous casting: use stopper tundish; use the cast of submerged nozzle full guard, wherein, two cold employings are weak cold; crystallizer adopts non-sinusoidal oscillation; liquidus temperature is 1509 DEG C, and tundish superheating temperature is by 20～30 DEG C of controls, and middle bag the first furnace temperature is controlled at 1530～1535 DEG C; even watering heat is controlled at 1525～1533 DEG C; continuous caster is that 6 machines 6 flow, and casting blank specification is 165mm × 200mm, and pulling rate is 1.0～1.3m/min.
5) soaking temperature of process furnace is 1200～1210 DEG C, and finishing temperature is 880 DEG C in web central authorities, and stocking naturally cools to below 450 DEG C at cold bed, carry out water-cooled, after below rolled piece temperature is down to 100 DEG C, sends into straightener and align, finally rolled piece is cut to dimensioning.The 500MPa level fork truck gantry-shaped steel obtaining by aforesaid method consists of the following composition by weight percentage: C0.25～0.29%, Si0.20～0.30%, Mn1.20～1.25%, P≤0.025%, S≤0.015%, V0.065～0.075%, all the other are iron and inevitable impurity.
6) specific chemical composition of the steel that three embodiment obtain is referring to table 1, and converter steelmaking process recorder is in table 2, and refining process recorder is in table 3, and casting process recorder is in table 4, and operation of rolling recorder is in table 5, and stocking mechanical property recorder is in table 6.
Table 1: main chemical compositions weight percent (wt%) in steel
| Embodiment | C | Si | Mn | P | S | V |
| 1 | 0.26 | 0.28 | 1.24 | 0.016 | 0.006 | 0.07 |
| 2 | 0.29 | 0.29 | 1.25 | 0.019 | 0.003 | 0.072 |
| 3 | 0.27 | 0.29 | 1.24 | 0.019 | 0.008 | 0.074 |
Table 2: converter steelmaking process recorder
Table 3: refining process recorder
| Embodiment | Ca line feed quantity (m/ stove) | Little argon gas churning time (min) | Argon flow amount (NL/min) |
| 1 | 127 | 11 | 80 |
| 2 | 136 | 13 | 80 |
| 3 | 130 | 10 | 80 |
Table 4: casting process recorder
Table 5: operation of rolling recorder
Table 6: stocking mechanical property recorder
The thinking of carbon+vanadium micro-alloying+low S, P+ aluminium deoxidation+stopper tundish during embodiment of the present invention process design adopts, middle carbon is applied seldom in shaped steel field, can effectively improve product strength, hardness and the mechanical property such as wear-resisting; Vanadium micro-alloying is by grain refining and separate out intensity and the toughness of the effect enhanced products such as precipitation; Low S, P control and can avoid steel to occur that normal temperature and low temperature brittleness rise, and improve steel toughness and security and stability thereof; Aluminium deoxidation can effectively reduce oxygen content in steel, reduces steel inclusion, improves Cleanliness of Molten Steel, improves product over-all properties.Stopper tundish can improve continuous casting steel liquid level stabilizing, reduces casting blank defect, and then enhances product performance.In addition, the soaking temperature of controlling process furnace in rolling step is 1200-1215 DEG C, can well make VN alloy fully dissolve, and plays the effect of crystal grain thinning, avoid occurring may causing coarse grains because Heating temperature is too high simultaneously, cause intensity not reach the situation of requirement.
Compare with gantry-shaped steel of forklift production at present, technical solution of the present invention also has following features:
1) product does not add Nb alloy, can reduce strand crack sensitivity, significantly improves cc billet surface quality, can realize the continuous and stable production of 500MPa level fork truck gantry-shaped steel;
2) only add V alloy, after rolling, do not control cold and do not need to heat-treat, complete Composition Design and the production of 500MPa level fork truck gantry-shaped steel, reduce the cost of alloy of production process.
3) the product good mechanical properties that production method of the present invention is manufactured, yield strength average out to 531MPa, is the highest fork truck gantry-shaped steel of current domestic intensity.
Finally it should be noted that: above embodiment is the unrestricted technical scheme of the present invention in order to explanation only, although the present invention is had been described in detail with reference to above-described embodiment, will be understood by those skilled in the art that, still can modify or be equal to replacement the present invention, and not departing from any modification or partial replacement of the spirit and scope of the present invention, it all should be encompassed in the middle of claim scope of the present invention.
Claims (5)
1. a production method for gantry-shaped steel for 500MPa level fork truck, is characterized in that, comprises successively molten iron pre-desulfurization, converter smelting, LF refining, full guard continuous casting, rolling step, wherein:
In described molten iron pre-desulfurization step, after desulfurization, ensure that Sulfur Content in Hot Iron content is≤0.010wt%;
In described converter smelting step, adopt top and bottom combined blown converter smelting;
In described LF refinement step, in refining process, abundant stirringization slag, makes yellowish-white slag;
In described full guard continuous casting step, adopt the casting of submerged nozzle full guard;
In described rolling step, the soaking temperature of process furnace is 1200～1215 DEG C, finishing temperature is 880 DEG C in web central authorities, stocking naturally cools to 300-450 DEG C at cold bed, then carry out water-cooled, after below rolled piece temperature is down to 100 DEG C, sends into straightener and align, finally rolled piece is cut to dimensioning;
The 500MPa level fork truck that this production method obtains consists of the following composition by weight percentage with gantry-shaped steel: C0.24～0.30%, Si0.15～0.30%, Mn1.05～1.30%, P≤0.025%, S≤0.015%, V0.05～0.08%, all the other are iron and inevitable impurity.
2. production method according to claim 1, it is characterized in that, described 500MPa level fork truck consists of the following composition by weight percentage with gantry-shaped steel: C0.25～0.29%, Si0.20～0.30%, Mn1.15～1.25%, P≤0.025%, S≤0.015%, V0.065～0.075%, all the other are iron and inevitable impurity.
3. production method according to claim 1, is characterized in that, in converter smelting step, adopts the low rifle bit manipulation of the large quantity of slag, and converting process slag charge adds in two batches, adds in the first batch 2/3 slag charge; Adopt silicomanganese, middle manganese, vanadium nitrogen to carry out alloying, the target value of molten steel interalloy element is by the intermediate value control of respective element scope; Adopt aluminium manganese-ferro deoxidation, add-on 1.5～2.0kg/t steel; In tapping process, add synthetic slag 8～10kg/t steel, evenly add successively silicomanganese, middle manganese, aluminium ferromanganese, VN alloy, molten steel to go out to 3/4 o'clock to add when molten steel goes out to 1/4 time, alloy is aimed at steel stream and is impacted and go to add.
4. production method according to claim 1, it is characterized in that, in described LF refinement step, in described LF refinement step, also comprise that the omnidistance argon bottom-blowing of refining process stirs, the refining later stage feeds the pure calcium core-spun yarn of real core more than keeping the little argon gas stirring of top of the slag fine motion 10min before departures, feed quantity is 120～150m/ stove; Wherein, the little argon gas of described top of the slag fine motion refers to that argon flow amount is 50～150NL/min.
5. production method according to claim 1; it is characterized in that; in described full guard continuous casting step; use stopper tundish; use the cast of submerged nozzle full guard; wherein; two cold employings are weak cold, and crystallizer adopts non-sinusoidal oscillation, and liquidus temperature is 1509 DEG C; tundish superheating temperature is by 20～30 DEG C of controls; middle bag the first furnace temperature is controlled at 1530～1535 DEG C, and even watering heat is controlled at 1525～1533 DEG C, and continuous caster is that 6 machines 6 flow; casting blank specification is 165mm × 200mm, and pulling rate is 1.0～1.3m/min.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104711476A (en) * | 2015-03-12 | 2015-06-17 | 山东钢铁股份有限公司 | Channel steel for hot rolling of forklift portal and preparation method of channel steel |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103074545A (en) * | 2013-02-05 | 2013-05-01 | 莱芜钢铁集团有限公司 | High-strength low temperature hot rolling resistant channel steel for forklift gantry and preparation method for channel steel |
| CN103266273A (en) * | 2013-06-09 | 2013-08-28 | 安徽霍山科皖特种铸造有限责任公司 | Alloy material and method for manufacturing forklift beam by use of same |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103074545A (en) * | 2013-02-05 | 2013-05-01 | 莱芜钢铁集团有限公司 | High-strength low temperature hot rolling resistant channel steel for forklift gantry and preparation method for channel steel |
| CN103266273A (en) * | 2013-06-09 | 2013-08-28 | 安徽霍山科皖特种铸造有限责任公司 | Alloy material and method for manufacturing forklift beam by use of same |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104711476A (en) * | 2015-03-12 | 2015-06-17 | 山东钢铁股份有限公司 | Channel steel for hot rolling of forklift portal and preparation method of channel steel |
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