CN110777261A - A method for controlling surface cracks of titanium and titanium alloy ingots prepared by electron beam cooling bed furnace - Google Patents

Abstract

The invention relates to a surface crack control method for preparing titanium and titanium alloy ingots by electron beam cooling bed furnace. In the middle, the hydraulic cylinder that controls the electron beam cooling bed furnace is pushed up once every 15~25s, 3~5mm each time; the power of the No. 1 gun controlling the electron beam cooling bed furnace is 400~550kw, and the power of the No. 2 gun is 400~550kw The power of the No. 3 gun is 350~450kw, the power of the No. 4 gun is 250~350kw, and the water flow is controlled between 1500~1900L/min; and the melting speed and ingot pulling speed are controlled; ingot. The invention has a simple production process and is easy to operate and realize. By controlling the reverse thrust distance, reverse thrust frequency, smelting speed and other parameters, the surface cracks of the ingot are eliminated, the yield of the ingot is improved, and it is easy to popularize and apply.

Description

A method for controlling surface cracks of titanium and titanium alloy ingots prepared by electron beam cooling bed furnace

technical field

The invention belongs to the technical field of titanium and titanium alloy ingot preparation, and particularly relates to a surface crack control method for preparing titanium and titanium alloy ingots by an electron beam cooling bed furnace.

Background technique

Titanium and titanium alloys have the characteristics of low density and good resistance to marine atmospheric corrosion. Production practice has proved that titanium and titanium alloys have high melt viscosity and poor fluidity. When using copper mold crucibles to cast ingots, due to cooling (For example, the cooling water pressure is too low, the water temperature is too high, and the scale of the mold is too thick for a long time to reduce the thermal conductivity), factors such as power and pulling speed lead to a thin condensate shell, and the ingot is in the casting process due to the presence of the mold inner wall. The friction force has a strong tendency to crack. When the crack is slight, it will cause transverse cracks in the ingot and increase the amount of milling surface; when the crack is serious, the crack will be larger, which cannot be eliminated by milling and grinding, and waste ingots will be produced. , the loss is relatively large, so how to overcome the shortcomings of the existing technology is an urgent problem to be solved in the technical field of titanium and titanium alloy ingot preparation.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the deficiencies of the prior art and provide a method for controlling the surface cracks of titanium and titanium alloy ingots prepared by an electron beam cooling bed furnace, so as to eliminate the surface cracks of titanium and titanium alloy ingots and improve the ingot yield. .

For achieving the above object, the technical scheme adopted in the present invention is as follows:

A surface crack control method for preparing titanium and titanium alloy ingots by an electron beam cooling bed furnace, comprising the following steps:

Step 1: Prepare the raw material sponge titanium or titanium alloy material, and then load it into the Archimedes rotary feeder and spread the titanium or titanium alloy material on the primary and refining cooling beds, and pump it into the electron beam cooling bed melting furnace. Vacuum, when the vacuum degree reaches below 9 × 10 ^-3 hPa, the electron beam cooling bed melting furnace is preheated. When preheated to the furnace chamber, the titanium or titanium alloy materials in the initial refining cooling bed and the refining cooling bed are fully melted. At this time, the temperature of the titanium liquid is between 1700°C and 1900°C and the vacuum is stable below 9×10 ^-3 hPa, and the blanking smelting begins;

Step 2: During the smelting process, the hydraulic cylinder controlling the electron beam cooling bed furnace is pushed up once every 15~25s, 3~5mm each time;

The power of the No. 1 gun to control the electron beam cooling bed furnace is 400~550kw, the power of the No. 2 gun is 400~550kw, the power of the No. 3 gun is 350~450kw, the power of the No. 4 gun is 250~350kw, and the water flow is controlled at 1500~1900L /min;

And control the melting rate M _{melting rate} = 4.51×W×L×V; among them, the density of titanium or titanium alloy is calculated as 4.51g/ ^cm3 , W is the width of the mold, the unit is mm; L is the length of the mold, the unit is mm ; V is the actual smelting speed of the spindle per minute, the unit is mm/min;

At the same time, control the pulling speed V _{actual pulling speed} = (V+9) mm/min;

Step 3: After the smelting is completed, the ingot is produced after cooling for 4 hours, and the ingot is obtained.

Further, preferably, in step 1, the alloy material is briquetted and then loaded into the Archimedes rotary feeder.

Further, preferably, the M _{melting rate} is between 500kg and 800kg/h.

Compared with the prior art, the present invention has the following beneficial effects:

1. The production process of the present invention is simple, easy to operate and realize, and by controlling parameters such as reverse thrust distance, reverse thrust frequency, smelting speed, etc., the surface cracks of the ingot are eliminated, the yield of the ingot is improved, and it is easy to popularize and apply.

2. Titanium and titanium alloys smelted by the existing technology are prone to cracks (crack depth> 4mm). The surface defects of the milling machine can only be milled when the depth of the milling surface reaches more than 5mm. When the cracks are deep, the surface defects cannot be eliminated, which greatly reduces the product quality and quality. The ingot obtained by the invention has no casting defects, and can be used after simple milling by a milling machine (the depth of the milling surface is less than or equal to 3 mm), and obvious economic benefits can be obtained.

Detailed ways

The present invention will be further described in detail below in conjunction with the embodiments.

Those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention. If no specific technology or condition is indicated in the examples, the technology or condition described in the literature in the field or the product specification is used. If the materials or equipment used are not marked with the manufacturer, they are all conventional products that can be obtained through purchase.

Example 1

A surface crack control method for preparing titanium and titanium alloy ingots by an electron beam cooling bed furnace, comprising the following steps:

Step 1: Prepare the raw material sponge titanium or titanium alloy material, and then load it into the Archimedes rotary feeder and spread the titanium or titanium alloy material on the primary and refining cooling beds, and pump it into the electron beam cooling bed melting furnace. Vacuum, when the vacuum degree reaches below 9 × 10 ^-3 hPa, the electron beam cooling bed melting furnace is preheated. When preheated to the furnace chamber, the titanium or titanium alloy materials in the initial refining cooling bed and the refining cooling bed are fully melted. At this time, the temperature of the titanium liquid is between 1700°C and 1900°C and the vacuum is stable below 9×10 ^-3 hPa, and the blanking smelting begins;

Step 2: During the smelting process, the hydraulic cylinder controlling the electron beam cooling bed furnace is pushed up once every 15s, 3mm each time;

The power of the No. 1 gun to control the electron beam cooling bed furnace is 400~550kw, the power of the No. 2 gun is 400~550kw, the power of the No. 3 gun is 350~450kw, the power of the No. 4 gun is 250~350kw, and the water flow is controlled at 1500~1700L /min;

And control the melting rate M _{melting rate} = 4.51×W×L×V; among them, the density of titanium or titanium alloy is calculated as 4.51g/ ^cm3 , W is the width of the mold, the unit is mm; L is the length of the mold, the unit is mm ; V is the actual smelting speed of the spindle per minute, the unit is mm/min;

At the same time, control the pulling speed V _{actual pulling speed} = (V+9) mm/min;

Step 3: After the smelting is completed, the ingot is produced after cooling for 4 hours, and the ingot is obtained.

Example 2

A surface crack control method for preparing titanium and titanium alloy ingots by an electron beam cooling bed furnace, comprising the following steps:

Step 1: Prepare the raw material sponge titanium or titanium alloy material, and then load it into the Archimedes rotary feeder and spread the titanium or titanium alloy material on the primary and refining cooling beds, and pump it into the electron beam cooling bed melting furnace. Vacuum, when the vacuum degree reaches below 9 × 10 ^-3 hPa, the electron beam cooling bed melting furnace is preheated. When preheated to the furnace chamber, the titanium or titanium alloy materials in the initial refining cooling bed and the refining cooling bed are fully melted. At this time, the temperature of the titanium liquid is between 1700°C and 1900°C and the vacuum is stable below 9×10 ^-3 hPa, and the blanking smelting begins;

Step 2: During the smelting process, the hydraulic cylinder controlling the electron beam cooling bed furnace is pushed up once every 25s, 5mm each time;

The power of the No. 1 gun to control the electron beam cooling bed furnace is 400~550kw, the power of the No. 2 gun is 400~550kw, the power of the No. 3 gun is 350~450kw, the power of the No. 4 gun is 250~350kw, and the water flow is controlled at 1700~1900L /min;

And control the melting rate M _{melting rate} = 4.51×W×L×V; among them, the density of titanium or titanium alloy is calculated as 4.51g/ ^cm3 , W is the width of the mold, the unit is mm; L is the length of the mold, the unit is mm ; V is the actual smelting speed of the spindle per minute, the unit is mm/min;

At the same time, control the pulling speed V _{actual pulling speed} = (V+9) mm/min;

Step 3: After the smelting is completed, the ingot is produced after cooling for 4 hours, and the ingot is obtained.

In step 1, the alloy material is briquetted and then loaded into the Archimedes rotary feeder.

The M _{melting rate} is between 500kg and 800kg/h.

Example 2

A surface crack control method for preparing titanium and titanium alloy ingots by an electron beam cooling bed furnace, comprising the following steps:

Step 1: Prepare the raw material sponge titanium or titanium alloy material, and then load it into the Archimedes rotary feeder and spread the titanium or titanium alloy material on the primary and refining cooling beds, and pump it into the electron beam cooling bed melting furnace. Vacuum, when the vacuum degree reaches below 9 × 10 ^-3 hPa, the electron beam cooling bed melting furnace is preheated. When preheated to the furnace chamber, the titanium or titanium alloy materials in the initial refining cooling bed and the refining cooling bed are fully melted. At this time, the temperature of the titanium liquid is between 1700°C and 1900°C and the vacuum is stable below 9×10 ^-3 hPa, and the blanking smelting begins;

Step 2: During the smelting process, the hydraulic cylinder controlling the electron beam cooling bed furnace is pushed up once every 20s, 4mm each time;

The power of the No. 1 gun to control the electron beam cooling bed furnace is 400~550kw, the power of the No. 2 gun is 400~550kw, the power of the No. 3 gun is 350~450kw, the power of the No. 4 gun is 250~350kw, and the water flow is controlled at 1500~1900L /min;

And control the melting rate M _{melting rate} = 4.51×W×L×V; among them, the density of titanium or titanium alloy is calculated as 4.51g/ ^cm3 , W is the width of the mold, the unit is mm; L is the length of the mold, the unit is mm ; V is the actual smelting speed of the spindle per minute, the unit is mm/min;

At the same time, control the pulling speed V _{actual pulling speed} = (V+9) mm/min;

Step 3: After the smelting is completed, the ingot is produced after cooling for 4 hours, and the ingot is obtained.

In step 1, the alloy material is briquetted and then loaded into the Archimedes rotary feeder.

The M _{melting rate} is between 500kg and 800kg/h.

Applications

Take 200*1250mm mold for smelting 8000mm titanium alloy as an example

Step 1: Preparatory work before smelting, replace 200mm*1250mm mold, prepare titanium or titanium alloy material (alloy material for briquetting), charge, evacuate and preheat, and reach the smelting conditions;

Specifically: prepare raw material - sponge titanium or titanium alloy material (briquetting is required to ensure element segregation small alloy material), then load it into the Archimedes rotary feeder and spread titanium into the primary refining cooling bed and the refining cooling bed Or titanium alloy material, vacuumize the electron beam cooling bed melting furnace, and preheat the electron beam cooling bed melting furnace when the vacuum degree reaches below 9×10 ^-3 hPa (with 1#, 2#, 3# guns) Low-power sweeping of the raw materials in the refining cooling bed and the primary refining cooling bed to eliminate the moisture in the furnace chamber), when preheated to the furnace chamber, the titanium or titanium alloy material in the primary refining cooling bed and the refining cooling bed is fully melted, and the temperature of the titanium liquid is at When the temperature is between 1700℃ and 1900℃ and the vacuum is stable below 9×10 ^-3 hPa, start the blanking smelting;

Step 2: Control the flow direction of the servo valve oil circuit and the amount of oil by changing the PLC program, realize the reverse thrust of the hydraulic cylinder, eliminate friction and secondary cooling, increase the thickness of the condensate shell, and realize the upward push 3 times per minute, each time 3mm (push every 20s);

Step 2: Control the power of the No. 1 gun of the electron beam cooling bed furnace to be 400~550kw, the power of the No. 2 gun to be 400~550kw, the power of the No. 3 gun to be 350~450kw, the power of the No. 4 gun to be 250~350kw, and the water flow to be controlled at Between 1500~1900L/min, the guaranteed melting rate: M _{melting rate} =1.1275×V; (W is the mold width 200mm, L is the mold length 1250mm)

Based on 600kg/h, it is obtained: V=8.87mm/min, V _{actual pulling speed} =17.87mm/min,

Step 3: According to the above smelting requirements, the smelting is completed in about 15 hours, and then the ingot is produced after post-cooling for 4 hours to obtain an ingot with excellent surface quality.

Through research, the present invention finds that the ratio of the ingot pulling rate to the cooling rate should be above 0.1, which indicates the stability of energy conservation and ultimately ensures the stability of the smelting process. Severity, cracks cannot be completely eliminated due to some other factors in smelting (volatiles in the furnace chamber, the focusing stability of the gun, the inevitable friction between the mold and the ingot shell, etc.).

After that, adjust the casting speed through experiments and maintain a stable speed, constant power, and constant water flow, and change the PLC program to control the oil inlet and oil return and oil volume of the servo valve, so as to control the hydraulic cylinder to achieve reverse rotation every 15~25s fixed time interval. Push 1 time, push up 3~5mm each time, mainly to eliminate friction and secondary cooling of the ingot to increase the thickness of the condensed shell, and it is not easy to produce cracks. The surface quality of the ingot produced by this method is good, and there is no casting defect. It can be used simply by milling the surface, which greatly improves the yield of the ingot and obtains obvious economic benefits.

At present, when the ingot is smelted and pulled normally, due to the friction between the ingot shell and the mold, the mold release of the ingot is a tensile stress mold release, which is prone to cracks, especially when the equipment works for a long time, the cooling performance of the mold decreases and the surface smoothness deteriorates. This leads to the thinning of the solidified shell and the increase of friction, and the smelted titanium and titanium alloys are more prone to cracks (crack depth> 4mm). The surface defects of the milling machine can only be milled when the depth of the milling surface reaches more than 5mm. When the cracks are deep, the surface defects cannot be eliminated. The product quality and the yield of finished products are greatly reduced. Under the stable pulling speed of the present invention, by pushing upwards, the demoulding of the ingot is compressive stress demoulding, and the secondary ingot shell cooling will not produce cracks. The ingots that can also be produced under the above-mentioned external conditions have no casting defects, and products with high yield and good quality can be obtained after simple milling by a milling machine (the depth of the milling surface is less than or equal to 3 mm).

The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments, and the descriptions in the above-mentioned embodiments and the description are only to illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have Various changes and modifications fall within the scope of the claimed invention. The claimed scope of the present invention is defined by the appended claims and their equivalents.

Claims (3)

1. an electron beam cooling bed furnace prepares the surface crack control method of titanium and titanium alloy ingot, is characterized in that, comprises the steps: Step 1: Prepare the raw material sponge titanium or titanium alloy material, and then load it into the Archimedes rotary feeder and spread the titanium or titanium alloy material on the primary and refining cooling beds, and pump it into the electron beam cooling bed melting furnace. Vacuum, when the vacuum degree reaches below 9 × 10 ^-3 hPa, the electron beam cooling bed melting furnace is preheated. When preheated to the furnace chamber, the titanium or titanium alloy materials in the initial refining cooling bed and the refining cooling bed are fully melted. At this time, the temperature of the titanium liquid is between 1700°C and 1900°C and the vacuum is stable below 9×10 ^-3 hPa, and the blanking smelting begins; Step 2: During the smelting process, the hydraulic cylinder controlling the electron beam cooling bed furnace is pushed up once every 15~25s, 3~5mm each time; The power of the No. 1 gun to control the electron beam cooling bed furnace is 400~550kw, the power of the No. 2 gun is 400~550kw, the power of the No. 3 gun is 350~450kw, the power of the No. 4 gun is 250~350kw, and the water flow is controlled at 1500~1900L /min; And control the melting rate M _{melting rate} =4.51×W×L×V; among them, the density of titanium or titanium alloy is calculated as 4.51g/ ^cm3 , W is the width of the mold, the unit is mm; L is the length of the mold, the unit is mm ; V is the actual smelting speed of the spindle per minute, the unit is mm/min; At the same time, control the pulling speed V _{actual pulling speed} = (V+9) mm/min; Step 3: After the smelting is completed, the ingot is produced after cooling for 4 hours, and the ingot is obtained. 2. electron beam cooling bed furnace according to claim 1 prepares the surface crack control method of titanium and titanium alloy ingot, it is characterized in that, in step 1, after the alloy material briquette is loaded into Archimedes and rotates again. feeder. 3. The surface crack control method for preparing titanium and titanium alloy ingots by electron beam cooling bed furnace according to claim 1, is characterized in that, described M _{melting rate} is between 500kg～800kg/h.