CN112795799B

CN112795799B - Cold cathode EB furnace smelting method of forging-free direct rolling Ti-Al-V-Fe alloy ingot

Info

Publication number: CN112795799B
Application number: CN202011323797.0A
Authority: CN
Inventors: 张玉勤; 张关梅; 张浩泽; 黄海广; 史亚鸣; 李志敏; 蒋业华
Original assignee: Kunming University of Science and Technology
Current assignee: Kunming University of Science and Technology
Priority date: 2020-11-23
Filing date: 2020-11-23
Publication date: 2021-11-26
Anticipated expiration: 2040-11-23
Also published as: CN112795799A

Abstract

The invention provides a cold cathode EB furnace smelting method of a forging-free direct rolling Ti-Al-V-Fe alloy ingot, which is characterized by comprising the following steps: 1) preparing materials, 2) mixing and briquetting, 3) charging, 4) starting No. 1-4 electron guns to carry out vacuum melting on bulk materials in a cooling bed to obtain a condensed shell, 5) pushing the pressed materials in a feeding area into a melting area, starting No. 1-7 electron guns to carry out vacuum melting and ingot pulling on the pressed materials, 6) feeding ingots by using No. 5-7 electron guns until titanium alloy liquid flows into a crystallizer completely through the cooling bed, and stopping melting to obtain the Ti-Al-V-Fe alloy ingot which is uniform in components and tissues, less in high-low density impurities, high in purity and capable of being directly rolled into a material without forging. The product performance is superior to the existing product, the process flow is short, the yield is improved to 80 percent, the cost is reduced by 15 to 30 percent, and the effect is obvious.

Description

Cold cathode EB furnace smelting method of forging-free direct rolling Ti-Al-V-Fe alloy ingot

Technical Field

The invention relates to a cold cathode EB furnace smelting method of a forging-free direct rolling Ti-Al-V-Fe alloy ingot, belonging to the technical field of nonferrous metal processing.

Background

The Ti-4Al-2.5V-1.5Fe alloy is a low-cost alpha + beta double-phase medium-high-strength titanium alloy, has mechanical properties equivalent to those of the Ti-6Al-4V alloy, but has good plasticity and toughness, can be subjected to hot processing and cold processing, and can be processed into products in various forms such as plates, strips, pipes, bars and the like; meanwhile, the alloy uses cheap Fe element to replace partial expensive V element, so that the alloy cost is reduced. Therefore, the method has wide application prospect in the fields of aerospace, ocean engineering, chemical engineering, electric power and the like. In the field of titanium material processing, sponge titanium and alloy raw materials are mixed according to a proportion and then smelted into a high-quality titanium alloy ingot with no segregation of chemical components, uniform tissue and less high-low density inclusions, which is an important basis of all subsequent titanium material processing processes, and only the high-quality titanium alloy ingot can be made into various high-quality titanium materials with stable batch performance through subsequent processing.

The existing Ti-Al-V-Fe alloy processing material generally adopts the following preparation process flow: firstly, mixing and assembling titanium sponge and alloy raw materials, then pressing and welding the materials into an electrode, smelting the electrode into a round ingot through a vacuum consumable arc furnace (VAR) for 2-3 times, then forging/cogging the round ingot, and then rolling and processing the round ingot into products such as pipes, plates, bars and the like. Although the alloy reduces the cost by using cheap Fe element, the alloy element only accounts for about 12 percent of the total cost in the cost composition of the titanium alloy raw material, so the cost reduction range is very limited; meanwhile, the problems that high-density and low-density impurities are difficult to remove, the components and the structure are not uniform, multiple remelting is needed and the like exist in the process of smelting the Ti-Al-V-Fe alloy by the VAR technology, so that an ingot must be forged, cogging and rolled into a material in subsequent processing, the process flow is long, the comprehensive yield is low, the cost of the processed material is high, and the large-scale application of the Ti-Al-V-Fe alloy is greatly limited.

Therefore, there is a need for an improvement in the prior art to provide a cold cathode EB furnace melting method for directly rolling Ti-Al-V-Fe alloy ingots without forging.

Disclosure of Invention

Because Ti-Al-V-Fe alloy contains volatile Al element, how to control or compensate the volatilization of the Al element under the condition of high vacuum of an EB furnace, and obtaining high-quality ingot casting which has uniform components and tissues, less high-low density impurities, high purity and can be directly rolled into finished products without forging through single melting is the technical problem to be solved by the invention.

The invention provides a cold cathode EB furnace smelting method of a forging-free direct rolling Ti-Al-V-Fe alloy ingot casting, aiming at solving the technical problems.

The invention is realized by the following technical scheme: a cold cathode EB furnace smelting method of a forging-free direct rolling Ti-Al-V-Fe alloy ingot is characterized by comprising the following steps:

(1) the materials are prepared according to the following mass ratio:

the sum of the above components is 100 wt.%;

(2) mixing the prepared materials in the step (1), taking a proper amount of mixture as bulk materials, pressing the rest of the mixture into blocks, drying the blocks at 100-120 ℃ for 5-6 h, and cooling the blocks along with a furnace to obtain pressed blocks;

(3) flatly paving the bulk material in the step (2) in an EB furnace cooling bed provided with a seven-rod electron gun, and then putting a proper amount of briquetting material in the step (2) into a feeding area of the EB furnace;

(4) closing the furnace door of the EB furnace, and vacuumizing to 1.8 multiplied by 10^-3～4.4×10^-3torr, then using hydrogen and oxygen to sweep the surface of the electron gun and dust in the furnace into the furnace for cleaning, and then continuously vacuumizing until the vacuum degree is 3.9 multiplied by 10^-3～4.4×10^- ³When torr is reached, opening No. 1-4 electron guns to smelt the bulk materials in the cooling bed, controlling the power of No. 1-4 electron guns to be 100-130 kW, after smelting for 100-120 min, closing the electron guns, cooling for 20-40 min to obtain a condensation shell, and cooling for 25-35 min along with the furnace;

(5) under a vacuum of 1.8X 10^-3～3.5×10^-3During torr, pushing the briquetting materials in the feeding area into a smelting area, starting No. 1-7 electron guns to smelt the briquetting materials, controlling the power of No. 1-2 electron guns to be 90-120 kW, the power of No. 3-4 electron guns to be 200-220 kW, the power of No. 5 electron guns to be 150-180 kW, the power of No. 6-7 electron beam guns to be 70-100 kW, enabling the smelted titanium alloy liquid to flow into a crystallizer through a cooling bed, pulling ingots at the speed of 12-18 mm/min, and continuously pushing, smelting and pulling ingots until the briquetting materials are completely smelted;

(6) heat 1 &No. 4 electron gun, vacuum degree of 1.8X 10^-3～3.5×10^-3And (3) feeding the cast ingot by using a No. 5-7 electron gun during torr, controlling the power of the No. 5-7 electron gun to be 70-100 kW until the titanium alloy liquid completely flows into the crystallizer through the cooling bed, closing the No. 5-7 electron gun, stopping ingot pulling, and cooling along with the furnace for 3-4 h to obtain the Ti-Al-V-Fe alloy cast ingot.

The content of Al in the aluminum beans in the step (1) is more than or equal to 99.9 wt.%.

The aluminum content of the aluminum-vanadium intermediate alloy in the step (1) is 45-50 wt.%, the V content is 50-55 wt.%, and the sum of the aluminum and the vanadium is 100 wt.%.

The content of Fe in the high-purity iron in the step (1) is more than or equal to 99.99 wt.%.

The content of TiO2 in the titanium dioxide in the step (1) is more than or equal to 98 wt.%.

And (4) the cast ingot in the step (6) is a round ingot or a flat ingot.

The ingot casting component of the step (6) is as follows: al: 3.5wt.% to 4.5wt.%, V: 2.0wt.% to 3.0 wt.%, Fe: 1.2wt.% to 1.8wt.%, O: 0.2wt.% to 0.3wt.%, the balance being Ti.

The invention has the following advantages and beneficial technical effects: by adopting the technology, the alloy proportion is scientific and reasonable, and corresponding process parameters are controlled in the smelting process of the EB furnace, so that the high-quality Ti-Al-V-Fe alloy ingot with uniform components and tissues, less high-low density impurities, high purity and capability of directly rolling the alloy without forging can be obtained by single smelting, the product performance is superior to the prior art, the process flow is shortened, the comprehensive yield of the product is improved to more than 80%, the production cost is reduced by 15-30%, and the method has obvious market application prospect.

Drawings

FIG. 1 is a schematic diagram of the electron gun distribution and the interior area of an EB furnace for melting round ingots.

FIG. 2 is another schematic view of the EB furnace interior zone and electron gun distribution for ingot melting.

FIG. 3 is an X-ray diffraction pattern of the ingot obtained in examples 1 to 3 of the present invention.

FIG. 4 is an optical microstructure of a round ingot melted in example 1 of the present invention.

FIG. 5 is an optical microstructure of a slab ingot melted in example 2 of the present invention.

FIG. 6 is an optical microstructure of a round ingot melted in example 3 of the present invention.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments, but the scope of the present invention is not limited to the description.

Example 1

The cold cathode EB furnace smelting method of the forging-free direct rolling Ti-Al-V-Fe alloy cast ingot is characterized by comprising the following steps:

(1) the materials are prepared according to the following mass ratio:

wherein: the content of Al in the aluminum beans in the step (1) is more than or equal to 99.9 wt.%;

the aluminum content of the aluminum-vanadium intermediate alloy in the step (1) is 45-50 wt%, and the V content is 50-55 wt%;

the content of Fe in the high-purity iron in the step (1) is more than or equal to 99.99 wt.%;

the content of TiO2 in the titanium dioxide in the step (1) is more than or equal to 98 wt.%;

(2) mixing the prepared materials in the step (1), taking a proper amount of the mixture as bulk materials, pressing the rest of the mixture into blocks, drying the blocks at 100 ℃ for 5 hours, and cooling the blocks along with a furnace to obtain pressed blocks;

(3) flatly paving the bulk material in the step (2) in an EB furnace cooling bed provided with a seven-rod electron gun, and then putting a proper amount of briquetting material in the step (2) into a feeding area of the EB furnace, wherein a circular crystallizer is adopted as a crystallizer of the EB furnace;

(4) closing the furnace door of the EB furnace, and vacuumizing to 4.4 multiplied by 10^-3torr, then using hydrogen and oxygen to sweep the surface of the electron gun and the dust in the furnace into the furnace for cleaning, sweeping the surface of the electron gun and the dust in the furnace into the furnace for cleaning, and then continuing to vacuumize until the vacuum degree is 4.4 multiplied by 10^-3When torr, turn on No. 1-4 electron gun to cool the bulk in the bedCharging materials and smelting, controlling the power of No. 1-4 electron guns to be 130kW, after smelting for 100min, closing the electron guns, cooling for 40min to obtain a condensation shell, and cooling for 25min along with the furnace;

(5) under vacuum degree of 3.5X 10^-3During torr, pushing the briquetting materials in the feeding area into a smelting area, starting No. 1-7 electron guns to smelt the briquetting materials, controlling the power of No. 1-2 electron guns to be 120kW, the power of No. 3-4 electron guns to be 220kW, the power of No. 5 electron guns to be 180kW, the power of No. 6-7 electron beam guns to be 100kW, enabling the smelted titanium alloy liquid to flow into a crystallizer through a cooling bed, pulling ingots at the speed of 18mm/min, and continuously pushing, smelting and pulling the ingots until the briquetting materials are completely smelted;

(6) turning off No. 1-4 electron gun at vacuum degree of 3.5 × 10^-3And (3) feeding the cast ingot by using No. 5-7 electron guns during torr, controlling the power of the No. 5-7 electron guns to be 100kW until the titanium alloy liquid completely flows into the crystallizer through the cooling bed, closing the No. 5-7 electron guns, stopping ingot pulling, and cooling along with the furnace for 3 hours to obtain the Ti-Al-V-Fe alloy round ingot.

The components of the round ingot are detected after being peeled, the periphery of each section is detected, one section is taken every 100mm, the detection result is shown in table 1, and the average deviation of the element content is very small from table 1, which shows that the ingot is uniform in components.

TABLE 1

Element(s)	Al	V	Fe	O
					Mean value of	4.05	2.38	1.47	0.25
Mean absolute deviation	0.074841	0.0266	0.014093	0.000516

Example 2

(1) the materials are prepared according to the following mass ratio:

(2) mixing the prepared materials in the step (1), taking a proper amount of the mixture as bulk materials, pressing the rest of the mixture into blocks, drying the blocks at 110 ℃ for 5.5 hours, and cooling the blocks along with a furnace to obtain pressed blocks;

(3) flatly paving the bulk material in the step (2) in an EB furnace cooling bed provided with a seven-rod electron gun, and then putting a proper amount of briquetting material in the step (2) into a feeding area of the EB furnace, wherein a flat crystallizer is adopted as a crystallizer of the EB furnace;

(4) shutting down EB furnaceOven door, vacuumizing to 2.5 × 10^-3torr, then using hydrogen and oxygen to sweep the surface of the electron gun and dust in the furnace into the furnace for cleaning, and then continuously vacuumizing until the vacuum degree is 4.2 multiplied by 10^-3When torr is carried out, opening No. 1-4 electron guns to smelt the bulk materials in the cooling bed, controlling the power of No. 1-4 electron guns to be 120kW, after smelting for 110min, closing the electron guns, cooling for 30min to obtain a condensation shell, and cooling for 30min along with the furnace;

(5) under vacuum degree of 2.8X 10^-3During torr, pushing the briquetting materials in the feeding area into a smelting area, starting No. 1-7 electron guns to smelt the briquetting materials, controlling the power of No. 1-2 electron guns to be 100kW, the power of No. 3-4 electron guns to be 210kW, the power of No. 5 electron guns to be 165kW, the power of No. 6-7 electron beam guns to be 80kW, enabling the smelted titanium alloy liquid to flow into a crystallizer through a cooling bed, pulling ingots at the speed of 13mm/min, and continuously pushing, smelting and pulling the ingots until the briquetting materials are completely smelted;

(6) turning off No. 1-4 electron gun at vacuum degree of 2.5 × 10^-3And (3) feeding the cast ingot by using a No. 5-7 electron gun during torr, controlling the power of the No. 5-7 electron gun to be 90kW until the titanium alloy liquid completely flows into the crystallizer through the cooling bed, closing the No. 5-7 electron gun, stopping ingot pulling, and cooling along with the furnace for 4 hours to obtain the Ti-Al-V-Fe alloy slab ingot.

And (3) removing the peel of the smelted slab ingot, then carrying out component detection, wherein 6 parts are taken on each section, 2 parts are taken on each wide surface, 1 part is taken on each narrow surface, one section is taken at an interval of 100mm, and the detection result is shown in table 2. As can be seen from Table 2, the average deviation of the element contents was small, indicating that the ingot composition was uniform.

TABLE 2

Element(s)	Al	V	Fe	O
					Mean value of	4.13	2.48	1.62	0.27
Mean absolute deviation	0.06752	0.0312	0.01026	0.000463

Example 3

(1) the materials are prepared according to the following mass ratio:

(2) mixing the prepared materials in the step (1), taking a proper amount of the mixture as bulk materials, pressing the rest of the mixture into blocks, drying the blocks at 120 ℃ for 5 hours, and cooling the blocks along with a furnace to obtain pressed blocks;

(3) flatly paving the bulk material in the step (2) in a cooling bed of an EB furnace provided with a seven-rod electron gun, and then putting a proper amount of briquetting material in the step (2) into a feeding area of the EB furnace, wherein a circular crystallizer is adopted as the crystallizer;

(4) closing the furnace door of the EB furnace, and vacuumizing to 1.8 multiplied by 10^-3torr, then using hydrogen and oxygen to sweep the surface of the electron gun and the dust in the furnace into the furnace for cleaning, sweeping the surface of the electron gun and the dust in the furnace into the furnace for cleaning, and then continuing to vacuumize until the vacuum degree is 3.9 multiplied by 10^-3When torr is carried out, opening No. 1-4 electron guns to smelt the bulk materials in the cooling bed, controlling the power of No. 1-4 electron guns to be 100kW, after smelting for 120min, closing the electron guns, cooling for 20min to obtain a condensation shell, and cooling for 35min along with the furnace;

(5) under a vacuum of 1.8X 10^-3During torr, pushing the briquetting materials in the feeding area into a smelting area, starting No. 1-7 electron guns to smelt the briquetting materials, controlling the power of No. 1-2 electron guns to be 90kW, the power of No. 3-4 electron guns to be 200kW, the power of No. 5 electron guns to be 150kW, the power of No. 6-7 electron beam guns to be 70kW, enabling the smelted titanium alloy liquid to flow into a crystallizer through a cooling bed, pulling ingots at the speed of 15mm/min, and continuously pushing, smelting and pulling the ingots until the briquetting materials are completely smelted;

(6) turning off No. 1-4 electron gun at vacuum degree of 1.8 × 10^-3And (3) feeding the cast ingot by using a No. 5-7 electron gun during torr, controlling the power of the No. 5-7 electron gun to be 70kW until the titanium alloy liquid completely flows into the crystallizer through the cooling bed, closing the No. 5-7 electron gun, stopping ingot pulling, and cooling along with the furnace for 3 hours to obtain the Ti-Al-V-Fe alloy round ingot.

And (3) peeling the round ingot, then carrying out component detection, taking the periphery of each section for detection, taking one section every 100mm, and obtaining the detection result shown in table 3. As can be seen from Table 3, the average deviation of the element contents was small, indicating that the ingot composition was uniform.

TABLE 3

Element(s)	Al	V	Fe	O
					Mean value of	4.29	2.61	1.58	0.25
Mean absolute deviation	0.07265	0.03951	0.02103	0.000384

As can be seen from the X-ray diffraction patterns of the corresponding examples 1, 2 and 3 in the attached figure 3, the circular ingots smelted by the invention mainly consist of alpha-Ti and beta-Ti phases.

As can be seen from the optical microscopic structure images of examples 1, 2 and 3 corresponding to FIGS. 4, 5 and 6, the cast ingot structure is a coarse sheet-like widmannstatten structure.

The round ingots smelted in the examples 1 and 3 are directly subjected to a cross rolling perforation process without forging to obtain the finished product

The large-diameter seamless pipe of (1) is obtained by taking a pipe sample 300mm long at the front end of the seamless pipe, annealing at about 870 ℃ in an Ar gas atmosphere, and then detecting the mechanical properties of the sample to obtain R_m＝920MPa，R_p0.2830MPa, 11.6% of A. The mechanical properties of the seamless tube obtained by forging and then cross-piercing the cast ingot obtained by VAR melting for a plurality of times by the conventional seamless tube rolling technique are shown in Table 4 after annealing. Therefore, the mechanical property of the Ti-Al-V-Fe alloy round ingot obtained by the technology of the invention is higher than that of the prior art by direct cross rolling and piercing without forging process, but the manufacturing process flow is shortened and the comprehensive yield and production cost are reduced compared with the prior art.

TABLE 4

Alloy (I)	R_m/MPa	R_p0.2/MPa	A/％
				Ti-Al-V-Fe	845	786	8

Directly carrying out a hot rolling process on the slab smelted in the example 2 without forging to obtain a 5mm plate, carrying out annealing treatment on the plate at about 900 ℃, and carrying out mechanical property detection on the plate to obtain R_m＝960MPa，R_p0.2850MPa, a 11.4%. The mechanical properties of the sheet obtained by forging and hot rolling an ingot obtained by VAR melting for a plurality of times by using the conventional sheet rolling technique are shown in Table 5 after annealing. Therefore, the Ti-Al-V-Fe alloy flat ingot obtained by the technology of the invention can be directly hot-rolled to obtain a plate without a forging processThe mechanical property of the material exceeds the level of the prior art.

TABLE 5

Alloy (I)	R_m/MPa	R_p0.2/MPa	A/％
				Ti-Al-V-Fe	827	758	6

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all the simple modifications, changes and equivalent structural changes of the above embodiments according to the technical spirit of the present invention still belong to the present invention.

Claims

1. A cold cathode EB furnace smelting method of a forging-free direct rolling Ti-Al-V-Fe alloy ingot is characterized by comprising the following steps:

(1) the materials are prepared according to the following mass ratio:

Al-V master alloy 4.5wt.% to 5.0 wt. -%)

Aluminum bean 3.5wt.% to 3.98 wt. -%)

High purity iron 1.2wt.% to 1.8wt. -%)

0.1-0.15 wt.% of titanium dioxide

Titanium sponge balance

The sum of the above components is 100 wt.%;

in the aluminum-vanadium intermediate alloy, the aluminum content is 45-50 wt.%, the V content is 50-55 wt.%, and the sum of the aluminum and the vanadium is 100 wt.%;

(4) closing the furnace door of the EB furnace, and vacuumizing to 1.8 multiplied by 10^-3～4.4×10^-3torr, then using hydrogen and oxygen to sweep the surface of the electron gun and dust in the furnace into the furnace for cleaning, and then continuously vacuumizing until the vacuum degree is 3.9 multiplied by 10^-3～4.4×10^-3When torr is reached, opening No. 1-4 electron guns to smelt the bulk materials in the cooling bed, controlling the power of No. 1-4 electron guns to be 100-130 kW, after smelting for 100-120 min, closing the electron guns, cooling for 20-40 min to obtain a condensation shell, and cooling for 25-35 min along with the furnace;

(6) turning off No. 1-4 electron gun at vacuum degree of 1.8 × 10^-3～3.5×10^-3During torr, feeding the cast ingot by using No. 5-7 electron guns, controlling the power of the No. 5-7 electron guns to be 70-100 kW, closing the No. 5-7 electron guns until titanium alloy liquid completely flows into the crystallizer through the cooling bed, stopping ingot pulling, and cooling along with the furnace for 3-4 h to obtain the Ti-Al-V-Fe alloy cast ingot, wherein the components of the cast ingot are as follows: al: 3.5wt.% to 4.5wt.%, V: 2.0wt.% to 30wt.%, Fe: 1.2wt.% to 1.8wt.%, O: 0.2wt.% to 0.3wt.%, the balance being Ti.

2. The cold cathode EB furnace smelting method of the forging-free direct rolling Ti-Al-V-Fe alloy ingot casting according to claim 1, wherein the Al content in the aluminum beans in the step (1) is more than or equal to 99.9 wt.%.

3. The cold cathode EB furnace smelting method of the forging-free direct rolling Ti-Al-V-Fe alloy ingot casting according to claim 1, wherein the content of Fe in the high-purity iron in the step (1) is more than or equal to 99.99 wt.%.

4. The cold cathode EB furnace smelting method of the forging-free direct rolling Ti-Al-V-Fe alloy ingot casting according to claim 1, wherein the step (1) is that TiO in titanium dioxide is adopted₂The content of (A) is more than or equal to 98 wt.%.

5. The cold cathode EB furnace smelting method of the forging-free direct rolling Ti-Al-V-Fe alloy ingot casting according to the claim 1, characterized in that the ingot casting of the step (6) is a round ingot or a flat ingot.