CN103170588B - A kind of warm type casting method - Google Patents

Abstract

The invention provides a warm mold casting method, which is characterized in that: the mold is heated by a heater, or the mold is heated by the heat conducted by the metal melt before entering the mold, so that the temperature of the mold is kept lower than that of the metal The solidus temperature is within the range higher than the cooling mold temperature; the metal is forcibly cooled by a cooler arranged near the mold outlet; the metal billet is drawn by a traction mechanism. The method of the invention has a wide range of applications, great promotion value, low energy consumption, excellent high-efficiency production performance, good surface finish, high dimensional accuracy, high density, relatively uniform composition, and the metal interior is parallel or approximately parallel to the casting direction The columnar grains and the equiaxed grains on the metal surface coexist with high-quality metal casting slabs with microstructures, and subsequent high-reduction plastic processing can be performed as required.

Description

A warm mold casting method

technical field

The invention belongs to the technical field of metal casting, and in particular provides a warm mold casting method.

Background technique

Casting plays a pivotal role in the production of metals. With the continuous increase of metal materials and product varieties, the rapid expansion of application fields, the rapid development of high-tech and the improvement of people's living standards, the world is facing the current situation of environmental degradation, resource and energy shortages, and the energy saving of metal casting process The requirements for consumption reduction, short process, high efficiency, low cost and slab quality are getting higher and higher.

The casting mold is a container for turning liquid metal into solid metal in casting and obtaining the required shape of the slab. It is the key component and "heart" in casting and plays an important role in the quality and output of the slab. At present, the molds used in metal casting mainly include cooling molds (referred to as "cold molds"), heating molds (referred to as "hot molds") and two-phase zone molds.

The traditional continuous casting method and semi-continuous casting method implemented in large-scale industrialization now use the cooling mold, that is, by applying circulating water around the mold for forced cooling, so that the temperature of the mold is much lower than the solidus temperature of the metal , the metal melt first solidifies under the rapid cooling of the mold, and gradually grows toward the center, and finally obtains the microstructure from the surface of the slab to the core, which are fine equiaxed crystals, columnar crystals perpendicular to the surface, and coarse equiaxed crystals. of cast blanks. The traditional continuous casting method and semi-continuous casting method using cooling molds have the advantages of high production efficiency, but there are defects such as easy formation of dendrites, segregation, shrinkage cavities and porosity, and the surface quality of the slab is poor. Face milling is required, material utilization rate is low, process flow is long, production cost is high, and billet deformation performance is generally poor, and product quality is difficult to meet higher requirements for use [Zhang Xiaoping, Liang Aisheng. Near net shape continuous casting technology. Beijing: Metallurgical Industry Press, 2001]; and for metals with a wide solid-liquid two-phase region, it is more difficult to prepare high-quality slabs by cold-type continuous casting.

The emerging semi-solid continuous casting method also uses cooling molds. By flowing the prepared semi-solid slurry into the cooling mold, the semi-solid slurry can be rapidly solidified under the chilling action around the mold, and the microstructure is obtained. A slab composed of a rosette-shaped or spherical non-dendritic primary phase and a fine eutectic crystal formed by quenching the remaining liquid phase [Flemings M C. Behavior of metal alloys in the semisolid state. Metallurgical and Materials Transactions A, 1991 , 22A (5): 957-981; Zhang Kui, et al. Electromagnetic Stirring Continuous Casting of Semi-Solid Aluminum Alloy and Analysis of Solidification Structure. Chinese Journal of Nonferrous Metals, 2000, 10 (1): 47-50]. The semi-solid continuous casting method is suitable for the preparation of metal billets with a solid-liquid two-phase region (especially a wide solid-liquid two-phase region). The obtained billets have fine grains, no macro segregation, uniform properties, and easy near-net forming. However, it cannot be used for casting of pure metals and eutectic alloys. The surface quality of the slab is poor, and defects such as shrinkage cavities and porosity are prone to occur inside the slab. The production efficiency is low, and the process parameters of the continuous casting process are not easy to control. The overall performance is difficult to meet the higher requirements of use and other deficiencies.

The continuous casting method using heated mold is called hot continuous casting method (also known as continuous directional solidification method). The mold temperature is higher than the liquidus temperature of the metal), and the solidified metal is forced to cool near the mold outlet, and a high temperature gradient along the casting direction is established between the solidified metal and the unsolidified melt, so that it has a directional Solidification conditions, so as to continuously obtain infinitely long cast slabs with unidirectional solidified continuous columnar crystals or single crystal structures. The casting slab with good surface finish, continuous columnar crystal or single crystal structure and excellent subsequent processing performance can be obtained by using the hot-type continuous casting method, but there are problems such as high mold heating temperature, high energy consumption, easy leakage, low production efficiency, The cross-sectional area of the product is small, and it is difficult to be used in the casting of metals with a wide solid-liquid two-phase region [Xie Jianxin, et al. New technologies and processes for material processing. Beijing: Metallurgical Industry Press, 2004].

The directional solidification method also uses the heating mold, which uses forced means during the solidification process to establish a temperature gradient in a specific direction between the solidified metal and the unsolidified melt, so that the melt is solidified in the direction opposite to the heat flow. A slab with unidirectional solidified columnar crystal or single crystal structure and excellent performance can be obtained, but there are high mold heating temperature, high energy consumption, limited slab length, equiaxed crystals are prone to appear on the top of the slab, and crystal Coarse particles, difficult to be used in casting of metals with a wide solid-liquid two-phase region, and low production efficiency [Zhou Yaohe, Hu Zhuangqi, Jie Wanqi. Solidification Technology. Beijing: Machinery Industry Press, 1998].

The casting method in the two-phase region is a new type of casting technology proposed by the inventors, and has been authorized as a national invention patent [Liu Xuefeng. A casting equipment and method whose mold temperature is the temperature of the solid-liquid two-phase region. Chinese invention patent, authorized No. ZL201010148612.7, authorization date 2012-10-03]. The two-phase zone casting method uses a two-phase zone mold, which controls the temperature of the mold within the temperature range of the solid-liquid two-phase zone of the metal (that is, by heating the mold, the temperature of the mold is kept at the solid phase of the metal. line temperature and liquidus temperature), and the solidified metal is forced to cool near the outlet of the mold in the two-phase region. Plastic processing performance, mechanical properties, physical properties and chemical properties are excellent, but they cannot be used for casting of pure metals and eutectic alloys, and there are disadvantages such as high mold heating temperature, high energy consumption, and too fast casting speed.

In summary, it is difficult to meet the requirements of relatively low energy consumption, high production efficiency, good surface and internal quality of the formed slab, and subsequent plasticity by adopting the existing cooling mold, heating mold and two-phase zone casting methods. Excellent processing performance and mechanical properties and other requirements. Therefore, in view of the problems existing in the current casting method, a new casting method with energy saving, high production efficiency and high yield rate is developed, so that the produced metal billet has good surface finish, compact structure, relatively uniform distribution of components, plastic processing performance and The mechanical properties and other comprehensive properties are excellent, which is of great significance.

Contents of the invention

The purpose of the present invention is to provide a warm mold casting method, which is to control the temperature of the mold in the low thermal temperature region of the metal (that is, by heating the mold, the temperature of the mold is kept below the solidus temperature of the metal and higher than the solidus temperature of the metal. Within the range of cooling mold temperature, this kind of mold is hereinafter referred to as "low heat mold") casting method (hereinafter referred to as "warm mold casting"). Since the temperature of the low-heat mold of warm mold casting is lower than the temperature of the heated mold and the two-phase zone mold, but higher than the temperature of the cooled mold, it can solve the problems produced by traditional continuous casting, semi-continuous casting and semi-solid casting methods. The surface finish, quality and performance of the slab are poor, the hot continuous casting method has low production efficiency and high energy consumption, it is difficult to produce a large cross-section slab, and it is easy to leak. The directional solidification method has low production efficiency and high energy consumption. The length is limited, the output is low, the energy consumption of the two-phase zone casting method is high, the casting speed cannot be too fast, and the semi-solid casting and two-phase zone casting methods cannot be used for the preparation of pure metals and eutectic alloys.

A warm mold casting method of the present invention is a warm mold casting method, which is a method of casting by controlling the temperature of the mold in the low heat temperature region of the metal by heating the mold, and the low heat temperature region refers to keeping the mold temperature In the range below the solidus temperature of the metal and above the temperature of the cooling mold; the mold whose temperature is controlled in the low heat temperature region of the metal is a low heat mold.

The warm mold casting method includes the steps of: flowing metal melt from a crucible into a low-heat mold; the low-heat mold is heated to the low-heat temperature region of the metal under the heat conduction action of a heater or the metal melt; The cooler directly forcibly cools the completely solidified metal surface, and under the action of the traction mechanism, the metal billet is continuously drawn; the cooling speed required for the metal is determined by the casting speed V of the traction mechanism, the cooling intensity of the cooler and heater to control.

Further, the heater adopts an external heat source or an induction heating coil.

Further, secondary cooling is implemented on the basis of the cooler provided near the outlet of the low-heat mold.

Further: the crucible is replaced by a tundish for continuous production.

Preferably, the warm mold casting method is to cast the crucible in an environment protected by air or vacuum or filled with nitrogen or filled with inert gas; the entire casting process can be controlled manually or by computer; warm mold casting The method can be any one of the pull-down type, arc type, horizontal type or upward type; according to the needs, the subsequent plastic processing can be directly carried out with a large reduction rate of 10% to 40%, so as to omit the intermediate annealing process.

Further, the warm mold casting method is to continuously add the prefabricated metal-solid-liquid mixture or semi-solid slurry into the tundish whose temperature is in the metal-solid-liquid two-phase region; place the tundish in air or vacuum or fill it with Nitrogen or an environment filled with inert gas protection; the entire casting and forming process is controlled manually or computerized; the warm mold casting method adopts any one of the pull-down, arc, horizontal or upward drawing; 10 can be used as required % to 40% of the large reduction rate of the pass can be directly followed by subsequent plastic processing, and the intermediate annealing process can be omitted.

Further, in the warm mold casting method, the heterogeneous phase materials required for the preparation of composite materials containing heterogeneous phases are first added to the metal melt; the crucible (2) is placed in air or vacuum or filled with nitrogen or It is filled in an environment protected by inert gas; the entire casting process is controlled manually or by computer; the warm mold casting method adopts any one of pull-down, arc, horizontal or upward drawing; 10%~ The subsequent plastic processing can be directly carried out with a large reduction rate of 40%, and the intermediate annealing process can be omitted.

The metal material prepared by the warm mold casting method has a microstructure in which columnar crystals inside the metal parallel or approximately parallel to the casting direction coexist with equiaxed crystals on the surface of the metal.

The main advantages of the present invention are:

1. The surface finish of the metal billet formed by the warm mold casting method is good, and it has a special microstructure (that is, the microstructure in which the columnar crystals inside the metal parallel or approximately parallel to the casting direction and the equiaxed crystals on the metal surface coexist), The structure is dense, the composition distribution is relatively uniform, and the plastic processing performance, mechanical properties, physical properties and chemical properties are better than ordinary casting billets of the same composition metal.

2. The warm mold casting method has a wide range of applications. Almost all metals can be formed by warm mold casting, such as pure metals, steel, aluminum alloys, copper alloys, titanium alloys, magnesium alloys, etc., and can also be used for layered casting of such metals. Composite materials, gradient composite materials and homogeneous composite materials can be formed, and metal wires, pipes, plates, strips, bars and profiles can be produced by near-net forming.

3. The warm mold casting method has great promotion value. As long as the cooling mold, heating mold and two-phase zone mold in the existing casting method are changed to low heat mold, the corresponding warm mold casting method can be developed .

4. The warm mold casting method saves energy, reduces consumption, and has high production efficiency.

5. The metal billet formed by the warm mold casting method can be subjected to subsequent plastic processing at a large reduction rate as required, and the intermediate annealing process can be omitted, which greatly simplifies the process, reduces the production cost, and improves the product quality.

Description of drawings

Fig. 1 is a schematic diagram of the principle of a warm mold casting method of the present invention. Among them (1) is the metal melt; (2) is the crucible; (3) is the low heat mold; (4) is the heater; (5) is the metal billet; (6) is the cooler; (7) is the lead Spindle rod; (8) is the traction mechanism.

Figure 2 is the longitudinal section microstructure of pure copper formed by warm mold casting.

Detailed ways

The present invention is specifically described below in conjunction with the examples, it is necessary to point out that the present examples are only used to further illustrate the present invention, and can not be interpreted as limiting the protection scope of the present invention, those skilled in the art can according to the above-mentioned present invention Make some non-essential improvements and adjustments to the content.

Example 1

A pure aluminum rod with a diameter of 20mm is formed by warm continuous casting. The pure aluminum melt 1 flows into the low-heat mold 3 from the crucible 2 filled with argon protection; the power of the induction heater 4 is adjusted to control the temperature of the low-heat mold 3 to 550°C; the temperature of the cooler 6 is 15°C, and the flow rate is 1000L/h of cooling water is used to forcibly cool the pure aluminum; the traction mechanism 8 performs continuous drawing at a casting speed of 50mm/min to obtain the pure aluminum rod 5 . The prepared pure aluminum rod has a good surface finish, dense internal structure, and the microstructure mainly consists of columnar crystals inside the pure aluminum rod parallel or approximately parallel to the casting direction and equiaxed crystals on the surface of the pure aluminum rod. Composition, and excellent quality and performance.

Example 2

The outer square side length is 20mm, and the inner circular hole diameter is 10mm. The pure copper profile is formed by warm casting. The pure copper melt 1 flows into the low-heat mold 3 from the crucible 2 filled with argon protection; the power of the induction heater 4 is adjusted to control the temperature of the low-heat mold 3 to 900°C; the temperature of the cooler 6 is 18°C, and the flow rate is The pure copper is forcibly cooled by 600L/h of cooling water; the drawing mechanism 8 is continuously drawn at a casting speed of 100mm/min to obtain the pure copper profile 5 . The prepared pure copper outer square inner circle profile has good inner and outer surface smoothness, dense internal structure, and the microscopic morphology mainly consists of columnar crystals inside the pure copper profile that are parallel or approximately parallel to the drawing direction and equiaxed crystals on the surface of the pure copper profile. Microstructural composition, and excellent quality and performance.

Example 3

Cu-12wt%Al aluminum-bronze alloy sheet with a width of 25mm and a thickness of 5mm was formed by warm-molding continuous casting. The Cu-12wt%Al aluminum bronze alloy melt 1 flows into the low-heat mold 3 from the crucible 2; the power of the induction heater 4 is adjusted to control the temperature of the low-heat mold 3 to be 850°C; the temperature of the cooler 6 is 20°C, and the flow rate is The Cu-12wt%Al aluminum bronze alloy was forcibly cooled by 800L/h cooling water; the traction mechanism 8 was continuously drawn at a drawing speed of 80mm/min to obtain the Cu-12wt%Al aluminum bronze alloy sheet 5. The prepared Cu-12wt%Al aluminum bronze alloy sheet has good surface finish, relatively uniform chemical composition distribution, dense internal structure, and microscopic morphology mainly composed of columnar crystals and aluminum bronze alloy sheets parallel or approximately parallel to the drawing direction inside the aluminum bronze alloy sheet. The surface layer of the alloy plate is composed of equiaxed crystals coexisting in the microstructure, and has excellent quality and performance.

Example 4

Al-4.5wt%Mg aluminum-magnesium alloy wire with a diameter of 10mm was formed by warm-mode continuous casting. Al-4.5wt%Mg aluminum-magnesium alloy melt 1 flows into the low-heat mold 3 from the crucible 2; the power of the induction heater 4 is adjusted to control the temperature of the low-heat mold 3 to be 500°C; the temperature of the cooler 6 is 17°C and the flow rate The Al-4.5wt%Mg aluminum-magnesium alloy was forcibly cooled with 1300L/h of cooling water; the drawing mechanism 8 was continuously drawn at a casting speed of 40mm/min to obtain the Al-4.5wt%Mg aluminum-magnesium alloy wire 5. The prepared Al-4.5wt%Mg aluminum-magnesium alloy wire has good surface finish, relatively uniform distribution of chemical components, and dense internal structure. The microstructure of equiaxed crystals coexists on the surface of the magnesium alloy wire rod, and its quality and performance are excellent.

Example 5

The BFe10-1-1 cupronickel alloy pipe with an outer diameter of 12mm and a wall thickness of 2mm is formed by warm-type continuous casting. BFe10-1-1 cupronickel alloy melt 1 flows from the crucible 2 into the low-heat mold 3; adjust the power of the induction heater 4 to control the temperature of the low-heat mold 3 to 920°C; the temperature of the cooler 6 is 15°C and the flow rate is 900L /h of cooling water to forcibly cool the BFe10-1-1 cupronickel alloy; the traction mechanism 8 performs continuous drawing at a drawing speed of 120 mm/min to obtain the BFe10-1-1 cupronickel alloy pipe 5 . The prepared BFe10-1-1 cupronickel alloy pipe has good internal and external surface finish, relatively uniform distribution of chemical components, and dense internal structure. The surface layer is composed of equiaxed crystals coexisting in microstructure, and has excellent quality and performance.

Example 6

Cu-4.7wt%Sn tin-bronze alloy wire with a diameter of 10mm was formed by warm-molding continuous casting. The Cu-4.7wt%Sn tin bronze alloy semi-solid slurry 1 with a solid phase volume fraction of 10% flows into the low-heat mold 3 from the crucible 2 filled with argon protection; adjust the power of the induction heater 4 to control the low-heat mold 3 The temperature is 830°C; the cooler 6 uses cooling water at a temperature of 20°C and a flow rate of 1000L/h to forcibly cool the Cu-4.7wt%Sn tin bronze alloy; the traction mechanism 8 performs continuous casting at a speed of 60mm/min drawing to obtain Cu-4.7wt%Sn tin bronze alloy wire 5. The prepared Cu-4.7wt%Sn tin-bronze alloy wire has good surface finish, relatively uniform distribution of chemical components, and dense internal structure. The surface layer of tin-bronze alloy wire is composed of equiaxed crystals and spherical crystals coexisting in the microstructure, and has excellent quality and performance.

Example 7

Aluminum matrix composite wire rod with a diameter of 15mm was formed by warm-type continuous casting. The aluminum matrix composite material melt 1 with Al ₂ O ₃ particle solid phase volume fraction of 15% flows into the low-heat mold 3 from the crucible 2 filled with argon protection; adjust the power of the induction heater 4 to control the temperature of the low-heat mold 3 The temperature is 570°C; the cooler 6 uses cooling water with a temperature of 18°C and a flow rate of 1200L/h to forcibly cool the aluminum matrix composite; the traction mechanism 8 performs continuous drawing at a drawing speed of 40mm/min to obtain an aluminum matrix composite Material Wire 5. The prepared aluminum-matrix composite material wire has good surface finish, relatively uniform distribution of Al ₂ O ₃ particles, and dense internal structure. Equiaxed crystals and Al ₂ O ₃ particles coexist in the surface layer of the matrix composite material, and the quality and performance are excellent.

Claims (8)

1. a warm type casting method, it is characterized in that: described warm type casting method is by heating the method being controlled by mold temperature to cast in the low heating temperature region of metal to casting mold, described low heating temperature region instigates mold temperature to remain on solidus temperature lower than metal and in scope higher than cooling mold temperature; It is low-heat casting mold that temperature controls at the casting mold in the low heating temperature region of metal; The metal material that described warm type casting method is prepared is that to have metal inside parallel or be approximately parallel to the column crystal in throwing direction and the equiax crystal of metal surface and the heterogeneous microstructure deposited.

2. a kind of warm type casting method according to claim 1, is characterized in that: described warm type casting method comprises step: metal bath (1) is flowed into low-heat casting mold (3) from crucible (2); Low-heat casting mold (3) is heated to the low heating temperature region of metal under heater (4) or metal bath (1) conductive force; Directly pressure cooling is carried out to the metal surface of solidifying completely by the cooler (6) arranged near low-heat casting mold (3) outlet, under the effect of haulage gear (8), continuous drawing metal strand (5); Cooling velocity needed for metal is controlled by the casting speed V of haulage gear (8), the intensity of cooling of cooler (6) and heater (4).

3. a kind of warm type casting method as claimed in claim 2, is characterized in that, described heater (4) adopts external heat source or load coil.

4. a kind of warm type casting method as claimed in claim 2, is characterized in that, cooling twice is implemented on the basis of the cooler (6) arranged near described low-heat casting mold (3) outlet.

5. a kind of warm type casting method according to claim 2, is characterized in that: described crucible (2) tundish replaces, for carrying out continuous seepage.

6. a kind of warm type casting method according to claim 2, is characterized in that: described warm type casting method, is crucible (2) be positioned over air or vacuum or cast in the environment that is filled with nitrogen or is filled with inert gas shielding; Whole cast form process adopts Artificial Control or computer to control; Warm type casting method is any one in pull-down, arc form, horizontal or top-guiding type; The passage heavy reduction rate of 10% ~ 40% is adopted directly to carry out follow-up plastic working as required, to omit intermediate annealing operation.

7. a kind of warm type casting method according to claim 1 or 5, is characterized in that: described warm type casting method prefabricated metal solid-liquid mixture or semi solid slurry is added temperature be continuously in the tundish of metal solid-liquid two-phase region; Tundish be positioned over air or vacuum or be filled with nitrogen or be filled with in the environment of inert gas shielding; Whole cast form process adopts Artificial Control or computer to control; Warm type casting method adopts any one in pull-down, arc form, horizontal or top-guiding type; The passage heavy reduction rate of 10% ~ 40% is adopted directly to carry out follow-up plastic working as required, to omit intermediate annealing operation.

8. a kind of warm type casting method according to claim 1 and 2, is characterized in that: described warm type casting method is in metal bath, be first added into heterogeneous phase material composite needed for of preparation containing heterogeneous phase; Crucible (2) is positioned over air or vacuum or is filled with nitrogen or is filled with in the environment of inert gas shielding; Whole cast form process adopts Artificial Control or computer to control; Warm type casting method adopts any one in pull-down, arc form, horizontal or top-guiding type; The passage heavy reduction rate of 10% ~ 40% is adopted directly to carry out follow-up plastic working as required, to omit intermediate annealing operation.