Casting method for 1Cr17Ni2 or 5CrNiMoV steel ingot
Technical Field
The invention belongs to the technical field of metallurgical casting, and particularly relates to a casting method for a 1Cr17Ni2 or 5CrNiMoV steel ingot.
Background
The 1Cr17Ni2 series is a steel type of martensitic stainless steel with better matching of strength and toughness. It has good corrosion resistance to aqueous solutions of oxidizing acids, most organic acids and organic salts. The alloy is generally applicable to parts such as shafts, piston rods, pumps and the like which require obdurability and corrosion resistance in the production of nitric acid and acetic acid and the industries of light industry, textile and the like. The 5CrNiMoV is high-wear-resistance hot forging die steel and has the following component design characteristics: good toughness, high strength and good wear resistance; the die steel produced by adopting an Electric Arc Furnace (EAF), refining (LT) and Vacuum (VD) has high purity and good performance.
The steel grades have excellent performances and are widely applied in specific fields, but the steel grades have higher requirements on inclusions in the actual production process, and particularly, oxygen in the air easily enters molten steel in the casting process at present, so that inclusions appear in casting blanks and the performance of steel is influenced; therefore, it is required to insulate the molten steel using an insulation apparatus during the casting of the molten steel. However, at present, the solidification of the steel similar to the steel is uneven during the solidification process of casting.
Through search, a patent "a multi-ingot-pack ingot vacuum casting apparatus" (publication No. CN204338807U) is disclosed, which discloses a multi-ingot-pack ingot vacuum casting apparatus comprising: the steel ladle is filled with molten steel, and a sliding water gap is arranged below the steel ladle; a tundish located below the ladle, the ladle communicating with the tundish through the sliding gate valve, the tundish having a plurality of casting gates; the tundish is connected with the vacuum tank cover through the vacuum seal base, a guide pipe is arranged on the vacuum tank cover and corresponds to the lower part of each casting nozzle, and the guide pipe is positioned in the vacuum seal base and extends into the vacuum tank cover; molten steel is solidified from the top in the casting process of the device, so that the integral quality of the cast ingot is deteriorated.
Disclosure of Invention
1. Problems to be solved
Aiming at the problem that cast ingots are unevenly distributed due to the fact that cast ingots are solidified from top to bottom in the casting process of existing equipment, the casting method for the 1Cr17Ni2 or 5CrNiMoV steel ingots is provided.
2. Technical scheme
In order to solve the problems, the technical scheme adopted by the invention is as follows:
the invention discloses a casting method for a 1Cr17Ni2 or 5CrNiMoV steel ingot, wherein the bottom of a middle injection pipe is communicated with the bottom of an ingot mold, molten steel is firstly cast at the top of the middle injection pipe, the molten steel is cast into the ingot mold from the bottom of the ingot mold through the middle injection pipe to reach the height of 13/20-19/20 of the ingot mold, and then the molten steel is cast into the ingot mold from the top of the ingot mold.
Preferably, during the process of casting the molten steel, the gas-tight cover is used for carrying out gas-tight protection on the molten steel opening.
Preferably, said airtight enclosure is switchable above the tundish and the ingot mould.
Preferably, a molten steel casting system is used, comprising an ingot casting unit, a gas tight enclosure and a moving unit; the ingot casting unit comprises a middle injection pipe and an ingot mold, and the airtight cover is arranged above the middle injection pipe and the ingot mold in a reciprocating manner through the moving unit; the airtight cover comprises a cover body shell and a second rotating shaft, the cover body shell consists of 2 half shells, the second rotating shaft is arranged at the joint of the half shells, and the half shells are rotatably connected through the second rotating shaft; the mobile unit comprises a first rotating shaft and a lifter, and the airtight cover is arranged on the first rotating shaft through the lifter.
Preferably, the cover body shell in the device is provided with a water gap accommodating hole, a casting accommodating hole and an injection pipe, the water gap accommodating hole is formed in the top of the cover body shell, the casting accommodating hole is formed in the bottom of the cover body shell, and the injection pipe is connected with an air source through a vent pipe.
Preferably, the bottom of the middle injection pipe is communicated with the bottom of the ingot mold through a drainage pipe, and a water cooling pipe is arranged at the lower part of the outer wall of the ingot mold.
Preferably, the paraffin is arranged on the inner side wall of the cover body shell, and the paraffin is uniformly arranged on the inner side wall of the cover body shell along the circumferential direction.
Preferably, the height of the cross section of the ingot mold from the bottom of the ingot mold is H, and the area of the cross section of the ingot mold is a continuously increasing function with respect to H.
Preferably, the injection pipe comprises an upper injection pipe and a lower injection pipe, the injection direction of the upper injection pipe is inclined upwards, the injection direction of the lower injection pipe is inclined downwards, the upper injection pipe is connected with the air source through an upper vent pipe, and the lower injection pipe is connected with the air source through a lower vent pipe.
Preferably, the water cooling pipe is provided with a water inlet and a water outlet, the height from the ground of the water inlet is D1, the height from the ground of the water outlet is D2, the distance from the ground of the highest position of the ingot mold is D3, D1 is less than D2, and D2: D3 is 1/4-1/3.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention relates to a casting method for a 1Cr17Ni2 or 5CrNiMoV steel ingot, wherein the bottom of a middle injection pipe is communicated with the bottom of an ingot mold, molten steel is firstly cast at the top of the middle injection pipe, the molten steel is cast into the ingot mold from the bottom of the ingot mold through the middle injection pipe to reach the height of 13/20-19/20 of the ingot mold, and then the molten steel is cast into the ingot mold from the top of the ingot mold; by the casting method, the heat dissipation condition of the molten steel is improved, the molten steel is solidified from bottom to top, and the components and the structure in the cast ingot are distributed more uniformly.
(2) According to the casting method for the 1Cr17Ni2 or 5CrNiMoV steel ingot, the airtight cover is used for carrying out airtight protection on a molten steel opening in the molten steel casting process; the airtight cover can be switched above the middle pouring pipe and the ingot mould, and in the used device, the airtight cover is movably arranged above the ingot casting unit through a first rotating shaft on the moving unit; the moving unit drives the airtight cover to move back and forth above the central pouring pipe and the ingot mold, so that the airtight cover can be conveniently moved above the central pouring pipe or the ingot mold at different stages of molten steel casting; the building cost is low, the use convenience is high, and the production efficiency is effectively improved.
Drawings
FIG. 1 is a top view of the open state of the half-shell of the apparatus used in the casting method of 1Cr17Ni2 or 5CrNiMoV steel ingot according to the present invention;
FIG. 2 is a top view of a state in which an airtight cover is positioned on a center nozzle in the casting method of a 1Cr17Ni2 or 5CrNiMoV steel ingot according to the present invention;
FIG. 3 is a top view showing the movement of the airtight cover in the casting method of 1Cr17Ni2 or 5CrNiMoV steel ingot according to the present invention;
FIG. 4 is a side view of an apparatus for use in a method of casting ingots of 1Cr17Ni2 or 5CrNiMoV according to the invention;
FIG. 5 is a front view of a device used in the casting method of a steel ingot 1Cr17Ni2 or 5CrNiMoV according to the invention;
FIG. 6 is a schematic view of the device of the airtight cover that can be used in the casting process of 1Cr17Ni2 or 5CrNiMoV steel ingots according to the present invention;
FIG. 7 is a schematic diagram showing the use state of the airtight cover in the casting method of the steel ingot of 1Cr17Ni2 or 5CrNiMoV of the present invention;
FIG. 8 is a schematic structural diagram of an ingot casting device in an embodiment 1 of the casting method of the invention, which can be used for casting 1Cr17Ni2 or 5CrNiMoV steel ingots;
FIG. 9 is a schematic structural diagram of an ingot casting device in an embodiment 2 of the casting method of the invention, which can be used for casting 1Cr17Ni2 or 5CrNiMoV steel ingots;
FIG. 10 is a schematic flow chart of a casting method for 1Cr17Ni2 or 5CrNiMoV steel ingots.
The reference numbers in the figures illustrate:
100. a middle injection pipe; 110. a thermal insulation layer; 120. a high temperature resistant layer; 130. a molten steel outlet; 200. an ingot mold; 210. a molten steel inlet; 300. a drainage tube; 400. a water-cooled tube; 410. a water inlet; 411. a water inlet flange; 420. a water outlet; 421. a water outlet flange; 500. molten steel;
600. a cover body housing; 601. a nozzle receiving hole; 602. casting the accommodating hole; 603. a half-shell; 610. refractory cotton; 620. the bottom of the cover body;
710. an upper blowing pipe; 711. an upper vent pipe; 720. a lower blowing pipe; 721. a lower vent pipe;
801. a ladle; 802. casting a water gap; 803. a ingot casting device; 810. a fixing member; 820. paraffin wax;
901. a first rotating shaft; 902. a lifter; 903. a second rotating shaft.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
According to the casting method for the 1Cr17Ni2 or 5CrNiMoV steel ingot, as shown in figure 10, the bottom of a middle injection pipe 100 is communicated with the bottom of an ingot mold 200, molten steel is firstly cast at the top of the middle injection pipe 100, the molten steel passes through the middle injection pipe 100 and is cast into the ingot mold 200 from the bottom of the ingot mold 200, and the molten steel is cast to 13/20-19/20 of the height of the ingot mold 200, wherein the value can be 3/4 or 17/20. The molten steel is then cast into the ingot mold 200 at the top of the ingot mold 200. By the above casting method, the molten steel at the bottom of the ingot mold 200 can be solidified first, so that the molten steel is solidified from bottom to top.
In the process of casting molten steel, an airtight cover is used for carrying out airtight protection on a molten steel opening; the gas-tight enclosure can be switched over the tundish 100 and the ingot mould 200.
The apparatus used in the method is shown in fig. 1 and comprises an ingot casting unit including a tundish 100 and an ingot mold 200, an airtight enclosure movably disposed above the tundish 100 and the ingot mold 200 back and forth by a moving unit, and a moving unit.
The moving unit comprises a first rotating shaft 901, the airtight cover is arranged on the first rotating shaft 901, the first rotating shaft 901 is driven by a motor to rotate, as shown in fig. 2, the first rotating shaft 901 drives the airtight cover to move back and forth above the central pouring pipe 100 and above the ingot mold 200, when molten steel needs to be switched from the central pouring pipe 100 to the ingot mold 200 for casting, as shown in fig. 3, the motor drives the first rotating shaft 901 to rotate, and the first rotating shaft 901 drives the airtight cover to move from the upper part of the central pouring pipe 100 to the upper part of the ingot mold 200 for isolation.
As shown in fig. 3, the moving unit further includes a lifter 902, the lifter 902 is disposed on the first rotating shaft 901 in a manner of moving up and down, in this embodiment, the lifter 902 includes a gear driven by a motor, a driving gear matched with the gear is disposed on the first rotating shaft 901, and in a case that the driving gear is matched with the gear, the motor drives the gear to rotate, so that the lifter 902 can lift on the first rotating shaft 901. The airtight cover is provided on the lifter 902, and the height of the airtight cover can be adjusted by the lifter 902.
The airtight cover of the present embodiment, as shown in fig. 6 to 7, includes a cover body casing 600, the cover body casing 600 is composed of 2 half casings 603, a second rotating shaft 903 is disposed at a joint of the 2 half casings 603, the half casings 603 are connected with a moving unit through the second rotating shaft 903, and the half casings 603 rotate relatively through the second rotating shaft 903 of the moving unit. As shown in fig. 4 and 5, this arrangement allows the cover body case 600 to wrap the top of the ingot mold 200 and the tundish 100 having a large steel inlet, thereby achieving effective separation of molten steel. The top of the cover body shell 600 is provided with a nozzle accommodating hole 601, refractory wool 610 is arranged around the nozzle accommodating hole 601, and the refractory wool 610 contacts the bottom of the ladle 801 in the casting process, so that the insulating effect can be achieved to a certain extent. The cover bottom 620 of the cover housing 600 is provided with a casting accommodation hole 602; during casting, as shown in the use state diagram of fig. 2, the casting nozzle 802 of the ladle 801 is inserted into the nozzle accommodating hole 601 from the top of the cover body housing 600, so that the casting accommodating hole 602 of the cover body bottom 620 surrounds the molten steel inlet of the ingot casting device 803, and the molten steel in the ladle 801 flows into the molten steel inlet of the ingot casting device 803 from the casting nozzle 802 through the interior of the cover body housing 600.
In this embodiment, the two half shells 603 of the cover body shell 600 are separately arranged, and during casting, the two separate half shells 603 are combined to surround the casting nozzle 802 of the ladle 801 and the molten steel inlet of the tundish 100 or the ingot mold 200, and then the lifting component drives the cover body shell 600 to move upwards, so that the refractory wool 610 at the top of the cover body shell 600 contacts the bottom of the ladle 801, and then the molten steel can be released.
In order to ensure the air seal effect, an upper blowing pipe 710 and a lower blowing pipe 720 are arranged in the cover body casing 600, the blowing direction of the upper blowing pipe 710 is inclined upwards, the blowing direction of the lower blowing pipe 720 is inclined downwards, the upper blowing pipe 710 is connected with an air source through an upper vent pipe 711, and the lower blowing pipe 720 is connected with the air source through a lower vent pipe 721. In the casting process, the obliquely arranged upper injection pipe 710 obliquely and upwardly injects argon gas, and the obliquely and upwardly injects argon gas to seal the gap between the top of the cover body shell 600 and the casting nozzle 802; the lower blowing pipe 720 which is arranged obliquely blows argon gas obliquely downwards, and the argon gas obliquely downwards blows the argon gas to seal the gap between the bottom 620 of the cover body and the ingot casting device 803. In this embodiment, the inclination angle of the upper blowing pipe 710 to the horizontal plane is 30 to 60 °, and the inclination angle of the lower blowing pipe 720 to the horizontal plane is 30 to 60 °.
In addition, a plurality of upper blowing pipes 710 and a plurality of lower blowing pipes 720 are provided, and the upper blowing pipes 710 are uniformly arranged along the circumferential direction inside the cover body case 600; so as to ensure the uniformity of argon blowing of the blowing pipe and the uniformity of the air seal effect. And the upper blowing pipe 710 and the lower blowing pipe 720 are at least provided with two layers in the height direction, and the arrangement of the multiple layers of blowing pipes can improve the air seal area, thereby further improving the air seal effect of the blowing pipes for blowing argon.
It should be noted that the paraffin 820 is disposed on the inner sidewall of the cover housing 600, and the paraffin 820 is uniformly disposed on the inner sidewall of the cover housing 600 along the circumferential direction. At the beginning of the casting process, the molten steel radiation heat enables the paraffin 820 to be burned, and then the residual oxygen in the cover body shell 600 is consumed by the paraffin 820, so that oxygen is prevented from entering the molten steel, and the molten steel is protected; and the uniform arrangement of the paraffin 820 makes the consumption of the oxygen remaining in the cover casing 600 more uniform and sufficient. The inner sidewall of the cover body case 600 is provided with a fixing member 810 protruding from the sidewall, and the paraffin 820 is fixed to the fixing member 810. The fixing member 810 may be a supporting plate/pin for fixing the wax 820 on the inner sidewall of the cover housing 600 more firmly.
As shown in FIG. 8, the height of the middle injection pipe 100 of the ingot unit is the same as that of the ingot mold 200, and the bottom of the middle injection pipe 100 and the bottom of the ingot mold 200 are communicated with each other through a draft tube 300. The middle injection pipe 100 is sequentially provided with the high-temperature-resistant layer 120 and the heat insulation layer 110 from inside to outside, and the thickness of the high-temperature-resistant layer 120 is smaller than that of the heat insulation layer 110, so that the heat dissipation of the molten steel 500 in the middle injection pipe 100 can be reduced; furthermore, the inlet of the middle pouring pipe 100 is provided with a liquid inlet funnel, which can prevent the molten steel 500 from splashing outside when the molten steel 500 is poured. It should be noted that the bottom of the central pouring tube 100 is provided with a molten steel outlet 130, the bottom of the ingot mold 200 is provided with a molten steel inlet 210, and the area of the molten steel outlet 130 is larger than that of the molten steel inlet 210, so that the molten steel 500 injection speed can be ensured, and the cooled finished product can be conveniently demoulded.
The ingot mold 200 is used for cooling the molten steel 500, and the outer wall of the ingot mold 200 is provided with the heat insulation layer, so that the molten steel 500 can be prevented from being cooled too fast, and the product quality is improved. The area of the upper cross section of the ingot mold 200 is larger than that of the lower cross section, the height from the cross section of the ingot mold 200 to the bottom of the ingot mold 200 is H, and the area of the cross section of the ingot mold 200 is a continuously increasing function related to H, so that the device has a structure with a large upper part and a small lower part; the design is beneficial to cooling the central part of the lower layer molten steel 500, so that the overall temperature is uniform, the defects of central segregation, central porosity and the like of the steel ingot are further reduced, and the quality of a finished product is improved.
The water cooling pipe 400 is arranged at the lower part of the outer wall of the ingot mould 200 in a surrounding mode, the water cooling pipe 400 is provided with a water inlet 410 and a water outlet 420, the ground clearance of the water inlet 410 is D1, the ground clearance of the water outlet 420 is D2, the ground clearance of the highest position of the ingot mould 200 is D3, D1 is less than D2, and D2: D3 is 1/4-1/3. Cooling the lower part of the ingot mold 200 by using flowing water to accelerate the cooling speed of the molten steel 500 at the lower layer; furthermore, the bottom-up water feeding mode can minimize the temperature of the flowing water contacted by the molten steel 500 at the lowest layer, and can discharge the hot water which has been used for cooling from the upper opening immediately, so as to achieve the best cooling effect. A gap is formed between the pipelines of the water-cooling pipes 400, so that heat exchange between the water-cooling pipes can be prevented, and the cooling effect of the water-cooling pipes is reduced. The water inlet 410 is provided with a water inlet flange 411, and the water outlet 420 is provided with a water outlet flange 421, so that the water cooling pipe 400 can be conveniently detached when the ingot mold 200 needs to be lifted.
In the present embodiment, the paraffin 820 is provided on the side wall of the inner upper portion of the cover body case 600, and the paraffin 820 is provided in the height direction at 1/3 to 1/2, which is the entire height of the cover body case 600, because the molten steel is mainly exposed at the upper portion in the cover body case 600, the paraffin 820 is mainly burned at the upper portion in the cover body case 600, and the molten steel is specifically protected. The water cooling pipe 400 is disposed in the heat insulating layer of the ingot mold 200, and the molten steel outlet 130 at the bottom of the tundish pipe 100 and the molten steel inlet 210 at the bottom of the ingot mold 200 are on the same horizontal line.
Example 2
As shown in fig. 9, the basic contents of this embodiment are different from those of embodiment 1 in that: the water cooling pipe 400 is disposed around the outside of the heat insulating layer of the ingot mold 200, and the molten steel outlet 130 at the bottom of the tundish pipe 100 and the molten steel inlet 210 at the bottom of the ingot mold 200 are on the same horizontal line.
The invention has been described in detail hereinabove with reference to specific exemplary embodiments thereof. It will, however, be understood that various modifications and changes may be made without departing from the scope of the invention as defined in the appended claims. The detailed description and drawings are to be regarded as illustrative rather than restrictive, and any such modifications and variations are intended to be included within the scope of the present invention as described herein. Furthermore, the background is intended to be illustrative of the state of the art as developed and the meaning of the present technology and is not intended to limit the scope of the invention or the application and field of application of the invention.
More specifically, although exemplary embodiments of the invention have been described herein, the invention is not limited to these embodiments, but includes any and all embodiments modified, omitted, combined, e.g., between various embodiments, adapted and/or substituted, as would be recognized by those skilled in the art from the foregoing detailed description. The limitations in the claims are to be interpreted broadly based the language employed in the claims and not limited to examples described in the foregoing detailed description or during the prosecution of the application, which examples are to be construed as non-exclusive. Any steps recited in any method or process claims may be executed in any order and are not limited to the order presented in the claims. The scope of the invention should, therefore, be determined only by the appended claims and their legal equivalents, rather than by the descriptions and examples given above.