CN103966503A - High-strength H-shaped steel for mast of forklift truck and manufacturing method thereof - Google Patents
High-strength H-shaped steel for mast of forklift truck and manufacturing method thereof Download PDFInfo
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- CN103966503A CN103966503A CN201410213192.4A CN201410213192A CN103966503A CN 103966503 A CN103966503 A CN 103966503A CN 201410213192 A CN201410213192 A CN 201410213192A CN 103966503 A CN103966503 A CN 103966503A
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Abstract
The invention discloses high-strength H-shaped steel for a mast of a forklift truck and a manufacturing method thereof. The manufacturing method comprises the following steps: (a) obtaining primary molten iron; (b) adopting the converter primary molten iron; (c) adjusting the content of V in the molten iron to 0.05wt%-0.1wt% and the content of Ni in the molten iron to 0.1wt%-0.2wt%, and when the content of P in the molten iron does not exceed 0.010wt%, tapping to steel ladles; (d) adjusting the content of Si, Mn, Nb and O in the molten iron in a process of tapping to the steel ladles; (e) adjusting the content of C and O in the molten iron in a steel ladle refining furnace; (f) carrying out continuous casting on the molten iron so as to obtain a continuous casting blank; and (g) roughly rolling, precisely rolling and straightening the continuous casting blank, thus obtaining the high-strength H-shaped steel for the mast of the forklift truck.
Description
Technical field
The present invention relates to a kind of door frame steel and manufacture method thereof, specifically, the present invention relates to a kind of forklift door frame High Strength H-Beam and manufacture method thereof.
Background technology
Forklift door frame hangs on the drive axle in fork truck front, and fork truck is inserted goods in the process of getting lifting, and forklift door frame can produce very large upsetting moment taking front driving axle as the centre of moment, and this upsetting moment requires forklift door frame to have high strength and high tenacity with steel.
The forklift door frame of prior art is generally 335MPa and 400MPa with the intensity rank of shaped steel, only has small part product can reach 420MPa and 475MPa.Conventionally require intensity and the toughness of forklift door frame steel high as much as possible.
Summary of the invention
The object of the invention is to overcome above-mentioned technical problem, a kind of forklift door frame High Strength H-Beam and manufacture method thereof are provided.
Forklift door frame according to the present invention by the chemical composition of High Strength H-Beam is: Ni, the Nb of 0.025wt%～0.05wt% of V, the 0.1wt%～0.2wt% of the Mn of the C of 0.24wt%～0.30wt%, the Si of 0.20wt%～0.40wt%, 1.2wt%～1.5wt%, the P that is no more than 0.020wt%, the S that is no more than 0.010wt%, 0.05wt%～0.1wt%, surplus is iron and inevitable impurity.
The manufacture method of High Strength H-Beam for forklift door frame according to the present invention, comprises the following steps: (a) first ironmaking water; (b), in the time that the S of molten iron content is no more than 0.01wt%, adopt converter just to make steel water; (c) adjusting the V content of molten steel is that 0.05wt%～0.1wt%, Ni content are 0.1wt%～0.2wt%, and at the P of molten steel content when being no more than 0.010wt%, tap to ladle; (d), in the process to ladle tapping, the Si content of adjusting molten steel is that 0.20wt%～0.38wt%, Mn content are that 1.2wt%～1.5wt%, Nb content are that 0.025wt%～0.05wt%, O content are for being no more than 50ppm; (e) the C content of adjusting molten steel in ladle refining furnace is that 0.24wt%～0.30wt%, O content are no more than 10ppm; (f) molten steel is carried out to continuous casting, to obtain continuous-cast blank; (g) continuous-cast blank is carried out to roughing, finish rolling and aligning, thereby obtain forklift door frame High Strength H-Beam.
According to exemplary embodiment of the present invention, in step (b), can adopt top and bottom combined blown converter just to make steel water, and can be the steel scrap that is no more than 0.01wt% to adding sulphur content in molten steel.
According to exemplary embodiment of the present invention, in step (b), can adopt in molten steel and add nitrogen-vanadium alloy to control the V content of molten steel, can adopt in molten steel and add nickel plate to control the Ni content of molten steel.
According to exemplary embodiment of the present invention, in step (d), can go out to 1/4 o'clock at molten steel, aiming at steel stream impact zone evenly adds the alloy of adjusting molten steel composition to control the content of the alloying element of molten steel, until going out to 3/4 o'clock, molten steel adds, wherein, can adopt in molten steel adds silicomanganese to control the Si content of molten steel, add high carbon ferromanganese alloy to control the Mn content of molten steel, add ferrocolumbium to control the Nb content of molten steel, add aluminum-manganese-iron alloy to control the O content of molten steel.
According to exemplary embodiment of the present invention, step (e) can also be included in the composition to molten steel in LF a refining unit and finely tune.
According to exemplary embodiment of the present invention, in step (e), can stir by omnidistance argon bottom-blowing, argon pressure in refining process can be controlled at 90NL/min～150NL/min, before departures, argon pressure can be controlled at 30NL/min～80NL/min, argon blowing time can be no less than 11min, can adopt at least one in carbide of calcium or silicon carbide that the slag before departures is adjusted into white slag or yellowish-white slag, the content of O that can adopt at least one in Si-Ca-Ba, silicomanganese or ferrosilicon to control departures molten steel is no more than 10ppm.
According to exemplary embodiment of the present invention, in step (f), continuous casting can adopt protection cast, and pulling rate scope can be controlled at 0.80m/min～0.90m/min
According to exemplary embodiment of the present invention, in step (g), roughing start rolling temperature is controlled at 1050 DEG C～1150 DEG C, and roughing finishing temperature is controlled at 950 DEG C～1050 DEG C, finish rolling start rolling temperature is controlled at 900 DEG C～950 DEG C, and finish rolling finishing temperature is controlled at 800 DEG C～850 DEG C.
According to forklift door frame according to the present invention High Strength H-Beam and manufacture method thereof, production technique is simple, makes door frame steel have excellent intensity and impelling strength by the microalloying of the V in molten steel, Nb, Ni element.In addition, door frame of the present invention has also reduced the manufacturing cost of door frame steel with the low levels of steel interalloy element.
Embodiment
The present invention, mainly for the forklift door frame problem of High Strength H-Beam in composition, smelting process, provides a kind of forklift door frame High Strength H-Beam and preparation method thereof.The forklift door frame that the method according to this invention is produced has excellent intensity and impelling strength with High Strength H-Beam.
Below in conjunction with exemplary embodiment, forklift door frame of the present invention is described further by High Strength H-Beam and manufacture method thereof.
Forklift door frame according to the present invention with the composition of High Strength H-Beam is: Ni, the Nb of 0.025wt%～0.05wt% of V, the 0.1wt%～0.2wt% of the Mn of the C of 0.24wt%～0.30wt%, the Si of 0.20wt%～0.40wt%, 1.2wt%～1.5wt%, the P that is no more than 0.020wt%, the S that is no more than 0.010wt%, 0.05wt%～0.1wt%, surplus is iron and inevitable impurity.
According to forklift door frame High Strength H-Beam of the present invention, its composition characteristic is that the content of P, S, O is low, and the add-on of V, Ni, Nb alloy is low, thereby is ensureing that product has under high-intensity prerequisite, realizes low cost production.The reason of doing is like this: in the prior art, for obtaining high-intensity product, conventionally adopt a large amount of noble alloys such as Nb, V that add to realize alloy strengthening, this situation can improve the production cost of product; And in the present invention, by reducing P, S content, improve Molten Steel Cleanliness, reduce the content of the inclusion in product, simultaneously, adopt at least one in cheap Si-Ca-Ba, silicomanganese and ferrosilicon to carry out final deoxygenation, make the oxygen level of forklift door frame of the present invention High Strength H-Beam be less than 10ppm, go out the Clean Steel of low oxygen content with low cost production.In addition, only need to add micro-V, Ni, Nb alloy, can ensure that product has under the prerequisite of high strength and high impact toughness, realizes low cost production simultaneously.In addition, in the present invention, add micro-V, Ni, Nb alloy, can thinning microstructure crystal grain, improve intensity and the toughness of steel, reduce superheated susceptivity and the temper brittleness of steel, and the production process control of steel-making and molding procedure is simple.
To the manufacture method of forklift door frame of the present invention High Strength H-Beam be described below.
Comprise just ironmaking water, just make steel water, LF stove (ladle refining furnace) refining, continuous casting and rolling according to the manufacture method of steel of the present invention.
First, first ironmaking water in blast furnace, in the time that the S of molten iron content is no more than 0.010wt%, is blended into converter by molten iron and carries out just steel-making water.
Secondly, the water of just making steel carries out in top and bottom combined blown converter, and the argon flow amount of argon bottom-blowing is 300NL/min～400NL/min, and the oxygen flow of top blast oxygen is 3Nm
3/ min～4.5Nm
3/ min, finishing slag basicity is controlled at below 3.0.Can in the process of bessemerizing, in molten steel, add sulphur content to be no more than the steel scrap of 0.01wt%, to reduce smelting cost, meanwhile, the steel scrap of selecting sulphur content to be no more than 0.01wt% can also be avoided the rising of the sulphur content of molten steel.In addition, steel scrap can also reduce liquid steel temperature as refrigerant, and the add-on of described steel scrap can be 20kg/t
steel～40kg/t
steel.VN alloy and nickel plate can be joined in molten steel with furnace charge, the V content of controlling molten steel is that 0.05wt%～0.10wt%, Ni content are 0.1wt%～0.2wt%, in the time that the P of molten steel content is no more than 0.010wt%, taps to ladle.
Then, in the process to ladle tapping, can go out to aim to 1/4 o'clock steel stream impact zone at molten steel adds the alloy of adjusting molten steel composition to control the alloying element content of molten steel, comprise being 0.20wt%～0.38wt% to the Si content that adds silicomanganese to control molten steel in molten steel, can be 1.2wt%～1.5wt% to the Mn content that adds high carbon ferromanganese alloy alloy to control molten steel in molten steel, and can be 0.025wt%～0.05wt% to the Nb content that adds ferrocolumbium to control molten steel in molten steel, oxygen level from molten steel to the deoxidation treatment that adds aluminum-manganese-iron alloy to carry out molten steel in molten steel that can control is no more than 50ppm, and go out to 3/4 o'clock alloying element to add at molten steel.
According to one exemplary embodiment of the present invention, in the aluminum-manganese-iron alloy of the silicomanganese of the Si content that is used for adjusting molten steel and the O content that is used for controlling molten steel, contain Mn, in the process of component controlling, molten steel can pass through said process absorption portion Mn, therefore, can in molten steel, add high carbon ferromanganese alloy to adjust the Mn content of the rest part in molten steel, the Mn content that makes molten steel be 1.2wt%～1.5wt%.In addition, molten steel being carried out in the process of ladle refining processing, carry out deep deoxidation by least one that adds Si-Ca-Ba, silicomanganese and ferro-silicon in molten steel, due in this deoxidation process, have part Si and enter into molten steel, therefore, in tapping process, the content of controlling the Si in molten steel is no more than 0.38wt%, to prevent in deoxidation process making it higher than 0.40wt% because the Si in reductor is absorbed by molten steel the Si content that has increased molten steel.In the time that the reductor using in the process of molten steel in refining treatment comprises silicomanganese, for ensureing the Mn content in molten steel, the Mn content that should control molten steel in the process of molten steel tapping is not higher than 1.4wt%, and the Mn content that increases molten steel to avoid molten steel to use silicomanganese deoxidation in refining treatment process makes it exceed 1.5wt%.
Next, the molten steel in ladle is carried out to LF refining treatment.Specifically, LF refining process adopts omnidistance argon bottom-blowing to stir, and the argon pressure in refining process can be controlled at 90NL/min～150NL/min, and before departures, argon pressure can be controlled at 30NL/min～80NL/min, and argon blowing time is no less than 11min.Can in molten steel, add lime to carry out slag making according to practical situation, and can adopt at least one in carbide of calcium or silicon carbide that the slag before departures is adjusted into white slag or yellowish-white slag, and the hold-time of yellowish-white slag or white slag be no less than 10min.The O content that can adopt at least one in Si-Ca-Ba, silicomanganese or ferrosilicon to control molten steel is no more than 10ppm, and can be 0.24wt%～0.30wt% by the C content that adds carbon to adjust molten steel in molten steel.
In the time tapping to ladle, inevitably can bring a certain amount of converter slag in ladle.Converter slag phosphorus content is high, and under the effect of LF stove reducing atmosphere, a part of phosphorus in slag is got back in molten steel again, and P element is slightly increased.But, because P content is controlled at below 0.010wt% in the time of converter smelting molten steel, so although the reducing atmosphere of LF stove can make the content of the P in molten steel slightly increase, can not exceed 0.020wt%.
Finally, to carrying out continuous casting and rolling through the molten steel of ladle refining processing.In casting process, large water-coating port adds sealing-ring, to prevent N and the O in molten steel inspiration atmosphere, thus the cleanliness factor of raising molten steel.In addition, can adopt casing protection pouring type to pour into a mould molten steel, pulling rate scope can be controlled at 0.80m/min～0.90m/min.Cooling system adopts weak cold pattern (specific water is less than 0.28L/kg), can more be conducive to like this adsorption of covering slag to the inclusion in molten steel, also can avoid the secondary oxidation of molten steel.Molten steel (for example forms after continuous-cast blank through cast, molten steel can pour into through casting process the square billet that cross dimensions is 165mm × 200mm), continuous-cast blank can be through dephosphorize by high pressure water processing, the iron scale (phosphorus skin) forming in casting process to remove continuous-cast blank surface, is then rolled continuous-cast blank.Continuous-cast blank enters the roughing start rolling temperature of roughing can control 1050 DEG C～1150 DEG C, if continuous-cast blank tapping temperature cannot meet the described roughing start rolling temperature of continuous-cast blank, continuous-cast blank can be carried out to heat treated by process furnace, can be 2h～4h heat-up time, so that the temperature of continuous-cast blank reaches 1180 DEG C～1200 DEG C.Then the continuous-cast blank that meets breaking down temperature is rolled to processing.The operation of rolling can be divided into roughing and finish rolling.Roughing can adopt K1～K7 pass, rolling 7 passages altogether, and wherein K1, K2 can adopt conjugate pass, and coefficient of extension is not less than 8.5.Open water device for cooling after roughing mill, to reduce the roughing finishing temperature of continuous-cast blank, makes roughing finishing temperature can be controlled at 950 DEG C～1050 DEG C.Finish rolling start rolling temperature can be controlled at 900 DEG C～950 DEG C, and open water device for cooling after finishing mill, to reduce the finish rolling finishing temperature of continuous-cast blank, also can prevent excessively the growing up of crystal grain of continuous-cast blank and affect intensity and the impact property of material.Finishing temperature can be controlled at 800 DEG C～850 DEG C.Roughing and final rolling temperature by controlled rolling can make the interior microscopic tissue of the rolled piece after rolling form super-refinement ferrite crystal grain, by the combination of refined crystalline strengthening and precipitation strength, can significantly improve intensity, wear resistance and the impelling strength of the rolled piece of roll forming.On the complete rolled piece of rolling cold bed spray water cooling, until product temperature be down to 100 DEG C following after, rolled piece can be sent into straightener and align, finally rolled piece is cut to dimensioning.
According to steel of the present invention, strand can be rolled into H type, but the present invention is not limited to this, that is to say, can continuous-cast blank be rolled into according to the size of continuous-cast blank and the operation of rolling to the steel of other shapes, for example, pouring molten steel can be become to sectional dimension is that then the square billet of 165mm × 200mm becomes grooved through mill milling.
In addition, for fear of theme of the present invention is thickened, can omit the detailed description of the known technology/operation to comprising at this.Therefore, with in the manufacture method of steel, all can adopt prior art in this NM operation at high-strength H-shape forklift door frame of the present invention.
Below in conjunction with example, forklift door frame of the present invention is described further by High Strength H-Beam and manufacture method thereof, but the present invention is not limited to this.
Example 1
First, first ironmaking water in blast furnace, is 0.010wt% and molten iron temperature while being not less than 1280 DEG C at the S of molten iron content, molten iron is blended into converter and carries out just steel-making water.Just steel-making water carries out in top and bottom combined blown converter, and the argon flow amount of argon bottom-blowing is 340NL/min, and the oxygen flow of top blast oxygen is 3.8Nm
3/ min, finishing slag basicity is controlled at below 3.0.In molten steel, add 30kg/t in blowing simultaneously
steelthe sulphur content steel scrap that is 0.01wt%, add VN alloy and nickel plate simultaneously, the V content of controlling molten steel is that 0.06wt%, Ni content are 0.1wt%.And in the time that the P of molten steel content is 0.010wt%, tap to ladle.
In ladle tapping process, going out to aim to 1/4 o'clock at molten steel the Si content that steel stream impact zone adds silicomanganese, high carbon ferromanganese alloy, ferrocolumbium and ferro-aluminum manganese alloy to control molten steel is that 0.20wt%, Mn content are that 1.5wt%, Nb content are 0.025wt%, and goes out to 3/4 o'clock alloying element to add at molten steel.
Then, the molten steel in ladle is carried out to LF refining treatment.LF refining process adopts omnidistance argon bottom-blowing to stir, and the argon pressure in refining process is controlled at 95NL/min, and before departures, argon pressure is controlled at 40NL/min, and argon blowing time is 12min.Add lime to carry out slag making according to practical situation, and adopt carbide of calcium that the slag before departures is adjusted into white slag or yellowish-white slag, and the hold-time of yellowish-white slag or white slag is 10min.Adopt to the O content that adds Si-Ca-Ba to control molten steel in molten steel be 9ppm, the C content that adds carbon to adjust molten steel is 0.30wt%.
Afterwards, molten steel after treatment LF stove is poured into the square billet that sectional dimension is 165 × 200mm by continuous casting process.In casting process, large water-coating port adds sealing-ring and adopts the mode of casing protection cast to pour into a mould molten steel, and cooling system adopts weak cold pattern (specific water is less than 0.28L/kg), and pulling rate is 0.80m/min.The chemical composition of getting tundish steel sample analysis steel before continuous casting is: the V of Ni, the 0.06wt% of P, the 0.1wt% of S, the 0.015wt% of Mn, the 0.010wt% of the C of 0.30wt%, the Si of 0.22wt%, 1.50wt%, the Nb of 0.025wt%, all the other are Fe and inevitable impurity.
Molten steel, after continuous casting process pours into the continuous casting square billet that sectional dimension is 165mm × 200mm, carries out dephosphorize by high pressure water processing to continuous casting square billet surface.Then continuous casting square billet is sent into process furnace and carried out heat treated 2h, the temperature after process furnace heating reaches the continuous casting square billet of 1200 DEG C and carries out roughing and finish rolling.Roughing adopts K1～K7 pass, rolling 7 passages altogether, and wherein K1, K2 adopt conjugate pass, coefficient of extension is not less than 8.5, and the roughing start rolling temperature that continuous casting square billet enters roughing is 1150 DEG C, and roughing finishing temperature is 1050 DEG C, finish rolling start rolling temperature is 950 DEG C, and finish rolling finishing temperature is 850 DEG C.On the complete rolled piece of rolling, cold bed is sprayed water coolingly, until rolled piece temperature is down to after 90 DEG C, rolled piece is sent into straightener and align, and finally rolled piece is cut to dimensioning, obtains H shaped steel.
Example 2
First, first ironmaking water in blast furnace, is 0.008wt% and molten iron temperature while being not less than 1280 DEG C at the S of molten iron content, molten iron is blended into converter and carries out just steel-making water.Just steel-making water carries out in top and bottom combined blown converter, and the argon flow amount of argon bottom-blowing is 390NL/min, and the oxygen flow of top blast oxygen is 3Nm
3/ min, finishing slag basicity is controlled at below 3.0.In molten steel, add 20kg/t in blowing simultaneously
steelthe sulphur content steel scrap that is 0.008wt%, add VN alloy and nickel plate simultaneously, the V content of controlling molten steel is that 0.1wt%, Ni content are 0.16wt%.And in the time that the P of molten steel content is 0.008wt%, tap to ladle.
In ladle tapping process, going out to aim to 1/4 o'clock at molten steel the Si content that steel stream impact zone adds silicomanganese, high carbon ferromanganese, ferrocolumbium and aluminum-manganese-iron alloy to control molten steel is that 0.40wt%, Mn content are that 1.30wt%, Nb content are that 0.005wt%, O content are 46ppm, and goes out to 3/4 o'clock alloying element to add at molten steel.
Then, the molten steel in ladle is carried out to LF refining treatment.LF refining process adopts omnidistance argon bottom-blowing to stir, and the argon pressure in refining process is controlled at 120NL/min, and before departures, argon pressure is controlled at 50NL/min, and argon blowing time is 11min.Add lime to carry out slag making according to practical situation, and adopt silicon carbide that the slag before departures is adjusted into white slag or yellowish-white slag, and the hold-time of yellowish-white slag or white slag is 10min.The C content that to adopt silicomanganese and ferrosilicon to control O content in steel be 10ppm, add carbon to adjust in molten steel is 0.24wt%.
Afterwards, molten steel after treatment LF stove is poured into the square billet that sectional dimension is 165 × 200mm by continuous casting process.In casting process, large water-coating port adds sealing-ring and adopts the mode of casing protection cast to pour into a mould molten steel, and cooling system adopts weak cold pattern (specific water is less than 0.28L/kg), and pulling rate is 0.90m/min.The chemical composition of getting tundish steel sample analysis steel before continuous casting is: the V of Ni, the 0.10wt% of P, the 0.16wt% of S, the 0.013wt% of Mn, the 0.008wt% of the C of 0.24wt%, the Si of 0.40wt%, 1.30wt%, the Nb of 0.005wt%, all the other are Fe and inevitable impurity.
Molten steel, after continuous casting process pours into the continuous casting square billet that sectional dimension is 165mm × 200mm, carries out dephosphorize by high pressure water processing to continuous casting square billet surface.Then continuous casting square billet is sent into process furnace and carried out heat treated 3h, the temperature after process furnace heating reaches the continuous casting square billet of 1180 DEG C and carries out roughing and finish rolling.Roughing adopts K1～K7 pass, rolling 7 passages altogether, and wherein K1, K2 adopt conjugate pass, coefficient of extension is not less than 8.5, and the roughing start rolling temperature that continuous casting square billet enters roughing is 1100 DEG C, and roughing finishing temperature is 1000 DEG C, finish rolling start rolling temperature is 900 DEG C, and finish rolling finishing temperature is 800 DEG C.On the complete rolled piece of rolling, cold bed is sprayed water coolingly, until rolled piece temperature is down to after 100 DEG C, rolled piece is sent into straightener and align, and finally rolled piece is cut to dimensioning, obtains H shaped steel.
Example 3
First, first ironmaking water in blast furnace, is 0.009wt% and molten iron temperature while being not less than 1280 DEG C at the S of molten iron content, molten iron is blended into converter and carries out just steel-making water.Just steel-making water carries out in top and bottom combined blown converter, and the argon flow amount of argon bottom-blowing is 310NL/min, and the oxygen flow of top blast oxygen is 4.5Nm
3/ min, finishing slag basicity is controlled at below 3.0.In molten steel, add 40kg/t in blowing simultaneously
steelthe sulphur content steel scrap that is 0.08wt%, add VN alloy and nickel plate simultaneously, the V content of controlling molten steel is that 0.08wt%, Ni content are 0.2wt%.And be 0.008wt% at the P of molten steel content, tap to ladle.
In ladle tapping process, going out to aim to 1/4 o'clock at molten steel the Si content that steel stream impact zone adds silicomanganese, high carbon ferromanganese, ferrocolumbium and aluminum-manganese-iron alloy to control molten steel is that 0.30wt%, Mn content are that 1.40wt%, Nb content are that 0.040wt%, O content are 49ppm, and goes out to 3/4 o'clock alloying element to add at molten steel.
Then, the molten steel in ladle is carried out to LF refining treatment.LF refining process adopts omnidistance argon bottom-blowing to stir, and the argon pressure in refining process is controlled at 150NL/min, and before departures, argon pressure is controlled at 80NL/min, and argon blowing time is 11min.Add lime to carry out slag making according to practical situation, and adopt carbide of calcium that the slag before departures is adjusted into white slag or yellowish-white slag, and the hold-time of yellowish-white slag or white slag is 10min.The C content that to adopt ferrosilicon to control O content in steel be 9ppm, add carbon to adjust in molten steel is 0.27wt%.
Afterwards, molten steel after treatment LF stove is poured into the square billet that sectional dimension is 165mm × 200mm by continuous casting process.In casting process, large water-coating port adds sealing-ring and adopts the mode of casing protection cast to pour into a mould molten steel, and cooling system adopts weak cold pattern (specific water is less than 0.28L/kg), and pulling rate is 0.80m/min.The chemical composition of getting tundish steel sample analysis steel before continuous casting is: the V of Ni, the 0.08wt% of P, the 0.2wt% of S, the 0.015wt% of Mn, the 0.009wt% of the C of 0.27wt%, the Si of 0.30wt%, 1.40wt%, the Nb of 0.040wt%, all the other are Fe and inevitable impurity.
Molten steel, after continuous casting process pours into the continuous casting square billet that sectional dimension is 165mm × 200mm, carries out dephosphorize by high pressure water processing to continuous casting square billet surface.Then continuous casting square billet is sent into process furnace and carried out heat treated 3h, the temperature after process furnace heating reaches the continuous casting square billet of 1190 DEG C and carries out roughing and finish rolling.Roughing adopts K1～K7 pass, rolling 7 passages altogether, and wherein K1, K2 adopt conjugate pass, coefficient of extension is not less than 8.5, and the roughing start rolling temperature that continuous casting square billet enters roughing is 1080 DEG C, and roughing finishing temperature is 980 DEG C, finish rolling start rolling temperature is 920 DEG C, and finish rolling finishing temperature is 830 DEG C.On the complete rolled piece of rolling, cold bed is sprayed water coolingly, until rolled piece temperature is down to after 100 DEG C, rolled piece is sent into straightener and align, and finally rolled piece is cut to dimensioning, obtains H shaped steel.
Above example 1 is listed in table 1 to the performance of the H shaped steel of example 3, and wherein performance test methods adopts international method.
Table 1: H type door frame steel performance measurement in example 1～3
From table 1, the H shaped steel of manufacturing according to example 1 to example 3 has excellent intensity, hardness and impelling strength, therefore can be used for making forklift door frame.
In sum, compare with the production of H shaped steel with the forklift door frame of prior art, the feature of technical scheme of the present invention is as follows.
The first, converter is just made steel in water, adopts aluminum-manganese-iron alloy deoxidation, and in molten steel tapping process, at least one in employing Si-Ca-Ba, silicomanganese and ferrosilicon carried out final deoxygenation, makes forklift door frame of the present invention H type oxygen content in steel be less than 10ppm, produces the Clean Steel of low oxygen content.
The second, while producing square billet, use large water-coating port to add sealing-ring and adopt the mode of casing protection cast to carry out the cast of molten steel, improve the cleanliness factor of molten steel, realize permanent pulling rate, improve the quality of strand, produce high-strength mechanical manufacture steel.
The 3rd, add trace V, Ni, Nb alloy, use refined crystalline strengthening and the precipitation strength mechanism of alloying element, do not increasing under the prerequisite of production cost, improve intensity and the impelling strength of forklift door frame H shaped steel.
The 4th, the yield strength excellent property of H shaped steel for forklift door frame of the present invention, average out to 568MPa.
It will be understood by those skilled in the art that above embodiment is only illustrative, and infinite.Although the present invention is had been described in detail with reference to above-described embodiment, those of ordinary skill in the art is to be understood 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 (9)
1. a manufacture method for High Strength H-Beam for forklift door frame, described manufacture method comprises the following steps:
(a) first ironmaking water;
(b), in the time that the S of molten iron content is no more than 0.01wt%, adopt converter just to make steel water;
(c) adjusting the V content of molten steel is that 0.05wt%～0.1wt%, Ni content are 0.1wt%～0.2wt%, and P content in molten steel is when being no more than 0.010wt%, taps to ladle;
(d), in the process to ladle tapping, the Si content of adjusting molten steel is that 0.20wt%～0.38wt%, Mn content are that 1.2wt%～1.5wt%, Nb content are that 0.025wt%～0.05wt%, O content are for being no more than 50ppm;
(e) the C content of adjusting in ladle refining furnace in molten steel is that 0.24wt%～0.30wt%, O content are for being no more than 10ppm;
(f) molten steel is carried out to continuous casting, to obtain continuous-cast blank;
(g) continuous-cast blank is carried out to roughing, finish rolling and aligning, thereby obtain forklift door frame High Strength H-Beam;
Described forklift door frame by the chemical composition of High Strength H-Beam is: Ni, the Nb of 0.025wt%～0.05wt% of V, the 0.1wt%～0.2wt% of the Mn of the C of 0.24wt%～0.30wt%, the Si of 0.20wt%～0.40wt%, 1.2wt%～1.5wt%, the P that is no more than 0.020wt%, the S that is no more than 0.010wt%, 0.05wt%～0.1wt%, surplus is iron and inevitable impurity.
2. manufacture method as claimed in claim 1, wherein, in step (b), adopts top and bottom combined blown converter just to make steel water, and adds sulphur content to be no more than the steel scrap of 0.01wt% in molten steel.
3. manufacture method as claimed in claim 1, wherein, in step (b), adopts and adds nitrogen-vanadium alloy to control the V content in molten steel in molten steel, adopts and adds nickel plate to control the Ni content in molten steel in molten steel.
4. manufacture method as claimed in claim 1, wherein, in step (d), molten steel went out to 1/4 o'clock, aiming at steel stream impact zone evenly adds the alloy of adjusting molten steel composition to control the content of the alloying element of molten steel, until going out to 3/4 o'clock, molten steel adds, wherein, adopt adds silicomanganese to control the Si content of molten steel in molten steel, add high carbon ferromanganese alloy to control the Mn content of molten steel, add ferrocolumbium to control the Nb content of molten steel, add aluminum-manganese-iron alloy to control the O content of molten steel.
5. manufacture method as claimed in claim 1, wherein, step (e) also comprises, the composition to molten steel in LF a refining unit is finely tuned.
6. manufacture method as claimed in claim 1, wherein, in step (e), omnidistance argon bottom-blowing stirs, argon pressure in refining process is controlled at 90NL/min～150NL/min, before departures, argon pressure is controlled at 30NL/min～80NL/min, argon blowing time is no less than 11min, the slag before departures is adjusted into white slag or yellowish-white slag by least one in employing carbide of calcium or silicon carbide, adopts the content of the O of at least one the control departures molten steel in Si-Ca-Ba, silicomanganese or ferrosilicon to be no more than 10ppm.
7. manufacture method as claimed in claim 1, wherein, in step (f), continuous casting adopts protection cast, and pulling rate scope control is at 0.80m/min～0.90m/min.
8. manufacture method as claimed in claim 1, wherein, in step (g), roughing start rolling temperature is controlled at 1050 DEG C～1150 DEG C, roughing finishing temperature is controlled at 950 DEG C～1050 DEG C, finish rolling start rolling temperature is controlled at 900 DEG C～950 DEG C, and finish rolling finishing temperature is controlled at 800 DEG C～850 DEG C.
9. a forklift door frame High Strength H-Beam, described forklift door frame by the chemical composition of High Strength H-Beam is: Ni, the Nb of 0.025wt%～0.05wt% of V, the 0.1wt%～0.2wt% of the Mn of the C of 0.24wt%～0.30wt%, the Si of 0.20wt%～0.40wt%, 1.2wt%～1.5wt%, the P that is no more than 0.020wt%, the S that is no more than 0.010wt%, 0.05wt%～0.1wt%, surplus is iron and inevitable impurity.
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