Method and process for eliminating shrinkage and porosity of vacuum smelting master alloy bars：CNC Carbide Inserts：

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Method and process for eliminating shrinkage and porosity of vacuum smelting master alloy bars　[CNC Carbide Inserts] [編集]

The invention belongs to the technical field of smelting, and specifically relates to a method for eliminating shrinkage and porosity of a vacuum smelting master alloy bar.

Background technique:
During the casting and solidification of the master alloy, when the molten metal is poured into the ingot mold, since the temperature of the ingot mold where the master alloy is poured is significantly lower than the temperature of the molten metal, the temperature of the molten metal is quickly transferred to the ingot mold, which is close to the inner surface of the master alloy steel ingot mold. The molten metal solidifies rapidly, and the way the ingot solidifies is from the outside to the inside.The volume of the alloy shrinks during the solidification process, and shrinkage and porosity often appear at the last solidified part (center) of the master alloy.

When the master alloy is solidified, there is no continuous replenishment of molten metal above, and an open shrinkage cavity is formed in the head of the master alloy, which is a primary shrinkage cavity.The primary shrinkage cavity is usually through the use of an insulation riser to heat the solidified molten steel on the head to reduce the depth of the shrinkage cavity. After the ingot is cooled, the cap mouth is removed, which does not affect the internal quality of the alloy, but reduces the alloy yield rate. In the middle, the holes formed by the shrinkage of the final solidified part cannot be supplemented by the surrounding molten metal. A closed shrinkage cavity is formed inside the master alloy ingot, which is a secondary shrinkage cavity..Conventional casting method cannot eliminate secondary shrinkage.After the vacuum smelting master alloy is poured, there are often two problems in the ingot: one is that the primary shrinkage cavity is located at the uppermost end of the master alloy ingot and the shrinkage cavity is deep, and sometimes the depth of the shrinkage cavity even reaches 1/3 of the height of the master alloy. 1/2.The second is that the secondary shrinkage cavity exists inside the alloy ingot, which is continuous or discontinuous and cannot be removed.

Technical realization elements:
In view of the above-mentioned problems and deficiencies in the prior art, the present invention provides a method for eliminating shrinkage and porosity in vacuum smelting master alloy bars.

In order to achieve the above objectives, the present invention provides the following technical solutions:

A method for eliminating shrinkage and porosity in vacuum smelting master alloy bars. The method is carried out according to the following steps:

Step 1: Prepare the alloy raw materials according to the calculated batching list and load them into the melting crucible;

Step 2: Melt Tungsten Carbide Rods Crucible smelting for baking process and furnace washing process, the furnace washing process uses pure nickel or the same steel return material to wash the furnace;

Step 3: Baking and degassing the alloy raw materials;

Step 4: Bake the funnel brick and the shunt brick for 2 hours at 400C respectively;

Step 5: Use an annular heating furnace to heat the mold in the ingot chamber of the vacuum induction furnace;

Step 6: Smelt the alloy raw materials in the melting crucible under the condition of vacuum degree <4Pa to obtain alloy liquid;

Step 7: Pour the alloy liquid in step 6 into the mold;

Step 8: The mold is cooled and released. After the alloy liquid in the mold is fully solidified, the mold is demolded.

Further, in step 1, the melting crucible used is a magnesia or aluminum molding crucible.

Further, in step 5, the heating temperature of the casting mold is 600-650C.

Furthermore, in step 6, the process of smelting the alloy is divided into a melting period, a refining period and an alloying period. The melting period is to start with low power transmission, then gradually increase the power, increase the temperature in stages, and finally send the high power to the point The alloy raw materials are melted; the refining period is when the molten pool liquid level should remain calm, not bubbling, and the liquid level shall not turn over after the alloy raw materials are melted; the alloying period is when other required alloy elements are added to the alloy raw materials to be melted. Stir the molten pool to homogenize the alloy composition in the molten pool.

Further, in step 7, the superheating temperature of the alloy liquid is 100C-120C.

Further, in step 8, the cooling time of the mold is 10-15 minutes.

Compared with the prior art, the beneficial effects of the present invention are:

The invention is in vacuum inductionTungsten WeightThe ring heating furnace is used in the furnace to heat the mold. Because the mold is heated, when the alloy liquid is poured into the mold, the cooling and solidification rate of the alloy liquid in the mold is reduced, the fluidity of the molten metal is increased, and the surface of the ingot is smooth. The interior solidifies uniformly. During the solidification process, the casting speed is controlled according to the working conditions, so that the alloy liquid inside the mold solidifies from bottom to top, and the upper unsolidified alloy liquid supplements the lower solidification shrinkage, so that the solidified part of the master alloy is fully supplemented by the surrounding alloy liquid , The internal structure of the produced master alloy is dense, without holes, shrinkage and looseness.

Description of the drawings

Figure 1 is a schematic diagram of a longitudinal section of a master alloy with secondary shrinkage cavity without mold heating;

Figure 2 is a schematic diagram of the longitudinal section structure of the master alloy without secondary shrinkage after the mold is heated;

Figure 3 is a schematic diagram of the transverse macrostructure of the master alloy with secondary shrinkage cavity without mold heating;

Figure 4 is a schematic diagram of the transverse macrostructure of the master alloy without secondary shrinkage after the mold is heated.

Detailed ways

The present invention will be described in detail below through specific embodiments.

A method for eliminating shrinkage and porosity in vacuum smelting master alloy bars. The method is carried out according to the following steps:

Step 1: Prepare the alloy raw materials according to the calculated ingredient list and put them into the melting crucible, the melting crucible is magnesium or aluminum forming crucible;

Step 2: Smelt the crucible for the baking process and the furnace washing process. The furnace washing process uses pure nickel or the same steel return material to wash the furnace;

Step 3: Baking and degassing the alloy raw materials;

Step 4: Bake the funnel brick and the shunt brick for 2 hours at 400C respectively;

Step 5: Use an annular heating furnace to heat the mold in the ingot chamber of the vacuum induction furnace, and the heating temperature of the mold is 600-650C;

Step 6: Melt the alloy raw materials in the melting crucible under the condition of vacuum degree <4Pa to obtain the alloy liquid. The process of melting the alloy is divided into the melting period, the refining period and the alloying period. The melting period starts with low power transmission, and then Gradually increase the power, increase the temperature and melt in stages, and finally send the high power to the alloy raw materials to melt; the refining period is when the alloy raw materials are melted, the molten pool should remain calm, not bubbling, and the liquid surface should not turn over; alloying The expectation is that after adding other required alloying elements to the alloy raw materials, stirring the molten pool makes the alloy composition in the molten pool uniform;

Step 7: Pour the alloy liquid in step 6 into the mold, and the superheat temperature of the alloy liquid is 100��C-120��C;

Step 8: After the mold is cooled for 10-15 minutes, it is released. After the alloy liquid in the mold is fully solidified, the mold is demolded to obtain the master alloy.

Example 1

(1) Name of smelted alloy: K418.

(2) Ingredients: do ingredients and charge according to the calculated ingredients list.

(3) Preparation for smelting: 1) The smelting crucible adopts magnesia or aluminum molding crucible;

2) The crucible is baked and the furnace is washed, and the furnace washing process uses pure nickel or the same steel return material to wash the furnace;

3) Baking of raw materials: Baking and degassing the above raw materials of Ni, Co, Cr, W and Mo respectively;

4) Baking of refractory materials: hopper bricks and shunt bricks are respectively baked at 400C for 2 hours;

5) The ring heating furnace is used to heat the mold in the ingot chamber of the vacuum induction furnace, and the heating temperature of the mold is 600

(4) Vacuum smelting: smelt the alloy raw materials in the smelting crucible under the condition of vacuum degree<4Pa to obtain the alloy liquid. The process of smelting the alloy is divided into the melting period, the refining period and the alloying period. The melting period starts with low power delivery Then, the power is gradually increased, the temperature is increased in stages, and finally the high power is sent to the alloy raw materials to melt; the refining period is when the alloy raw materials are melted, the molten pool should be kept calm, not bubbling, and the liquid surface should not turn over. ; The alloying period is after adding other required alloying elements to the alloy raw materials, stirring the molten pool to homogenize the alloy composition in the molten pool.

(5) Pouring: When the temperature of the molten pool is appropriate, the molten pool can be charged after stirring. When the alloy liquid temperature is overheated by 100, turn the crucible to pour the alloy liquid into the funnel and pour into the mold according to the shunt plate.

(6) After the mold is cooled for 10 minutes, it is released. After the alloy liquid in the mold is fully solidified, the mold is demolded to obtain the master alloy.

Example 2

(1) Name of smelted alloy: K418.

(2) Ingredients: do ingredients and charge according to the calculated ingredients list.

(3) Preparation for smelting: 1) The smelting crucible adopts magnesia or aluminum molding crucible;

2) The crucible is baked and the furnace is washed, and the furnace washing process uses pure nickel or the same steel return material to wash the furnace;

3) Raw material baking: the above raw materials Ni, Co, Cr, W and Mo are baked and degassed;

4) Baking of refractory materials: hopper bricks and shunt bricks are respectively baked at 400C for 2 hours;

5) The ring heating furnace is used to heat the mold in the ingot chamber of the vacuum induction furnace, and the heating temperature of the mold is 620.

(4) Vacuum smelting: smelt the alloy raw materials in the smelting crucible under the condition of vacuum degree<4Pa to obtain the alloy liquid. The process of smelting the alloy is divided into the melting period, the refining period and the alloying period. The melting period starts with low power delivery Then, the power is gradually increased, the temperature is raised and melted in stages, and finally the high power is sent to the alloy raw materials to melt; the refining period is when the alloy raw materials are melted, the molten pool should remain calm, not bubbling, and the liquid surface should not turn over. ; The alloying period is after adding other required alloying elements to the alloy raw materials, stirring the molten pool to homogenize the alloy composition in the molten pool.

(5) Pouring: When the temperature of the molten pool is appropriate, the molten pool can be charged after stirring. When the alloy liquid temperature is over 110 turn the crucible to pour the alloy liquid into the funnel, and then pour into the mold according to the shunt plate..

(6) After the mold is cooled for 13 minutes, it is released. After the alloy liquid in the mold is fully solidified, the mold is demolded to obtain the master alloy.

Example 3

(1) Name of smelted alloy: K418.

(2) Ingredients: do ingredients and charge according to the calculated ingredients list.

(3) Preparation for smelting: 1) The smelting crucible adopts magnesia or aluminum molding crucible;

2) The crucible is baked and the furnace is washed, and the furnace washing process uses pure nickel or the same steel return material to wash the furnace;

3) Baking of raw materials: Baking and degassing the above raw materials of Ni, Co, Cr, W and Mo respectively;

4) Baking of refractory materials: hopper bricks and shunt bricks are respectively baked at 400C for 2 hours;

5) The ring heating furnace is used to heat the mold in the ingot chamber of the vacuum induction furnace, and the heating temperature of the mold is 650.

(4) Vacuum smelting: smelt the alloy raw materials in the smelting crucible under the condition of vacuum degree<4Pa to obtain the alloy liquid. The process of smelting the alloy is divided into the melting period, the refining period and the alloying period. The melting period starts with low power delivery Then, the power is gradually increased, the temperature is increased in stages, and finally the high power is sent to the alloy raw materials to melt; the refining period is when the alloy raw materials are melted, the molten pool should be kept calm, not bubbling, and the liquid surface should not turn over. ; The alloying period is after adding other required alloying elements to the alloy raw materials, stirring the molten pool to homogenize the alloy composition in the molten pool.

(5) Pouring: When the temperature of the molten pool is appropriate, the molten pool can be charged after stirring. When the alloy liquid temperature is overheated by 120, turn the crucible, pour the alloy liquid into the funnel, and pour into the mold according to the splitter plate..

(6) The mold is released after cooling for 15 minutes. After the alloy liquid in the mold is fully solidified, the mold is demolded to obtain the master alloy.

The improvement effect comparison diagram of the improved master alloy shrinkage cavity is shown in Figure 1 to Figure 4, and the production effect comparison of the improved master alloy is shown in Table 1..

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2021-02-06 14:59 nice!(0) コメント(1)