Method for making intermediate blank of (α+β) titanium alloys

FIELD: plastic metal working, possibly manufacture of intermediate blanks of titanium alloys by hot deforming.

SUBSTANCE: method comprises steps of deforming ingot at temperature in β -range and combination type operations of deforming blank temperature of (α + β) and β-ranges; at final deforming stage at temperature in (α + β) range realizing at least one forging operation after heating blank till temperature that is lower by 50 - 80°C than polymorphous conversion temperature of alloy; at least one time cooling blank in water; before deforming blank for final size, heating blank till temperature that is lower by 20 - 40°C than polymorphous conversion temperature for time period providing globule formation of α - phase; fixing formed structure by cooling in water; again heating blank till temperature that is lower by 20 - 40°C than polymorphous conversion temperature and finally deforming blank.

EFFECT: possibility for producing blank with globular-plate microstructure, lowered level of structural defects at ultrasonic flaw detection of turned blank.

1 ex

 

The invention relates to the field of metal forming, in particular, to methods for producing intermediate billets of titanium alloys by hot deformation.

A method of producing an intermediate blanks (α+β)-titanium alloys by the method of forging presses on the scheme, including hot deformation of bars after heating in the temperature range β-area 1050-1300°C, the deformation after heating at lower temperatures β-region (1000-1130° (C) and combined operations (α+β) - β-deformation, and heat before (α+β)-deformation is performed at temperatures of 20-40°below the temperature of polymorphic transformation (CCI) alloy (Titanium alloys. Alexandrov VK, Anoshkin NF and other Semi-finished products from titanium alloys. - M.: VILS, 1996, p.184-185, 189).

The use of such special ladder diagrams contributes to the development of recrystallization and the grinding plate structure that provides the Mat macrostructure 4-6 points and microstructure 3-5 type. However, for a number of products for critical application must meet higher requirements to the microstructure of the billet. The solution to this problem and directed the claimed invention.

The technical result achieved by this invention is a receipt for what otoki with homogeneous globular-lamellar microstructure and reducing structural noise during ultrasonic testing of machined billet.

This technical result is achieved by the fact that in the known method of manufacturing intermediate pieces (α+β)-titanium alloys, including the operation of deforming the ingot at temperatures of β-field and combined operations deformation of the workpiece in (α+β) - β-areas, according to the invention at the final stage of deformation in (α+β)-region of at least one of the forging operation is performed after heating the workpiece to a temperature at 50-80°below the temperature of polymorphic transformation of the alloy, with the workpiece, at least once, cooled in water, and before deformation on the final size of the workpiece is heated to a temperature of 20-40°below the temperature of polymorphic transformation of the alloy for a time, ensuring the passage of globularization α-phase, and record the resulting structure is cooled in water, after which the workpiece is again heated to a temperature of 20-40°lower Chamber of Commerce and permanently deform.

The essence of the invention is as follows.

Sequential deformation in β-, (α+β)-, β-areas provides significant crushing of initial coarse microstructure of the ingot. When deformation of the ingot in β-areas with ukonom not less than 2.5 coarse-grained structure of the ingot saves the I, when this frame is formed only with advanced technology of plasticity, gives the material the ability to perceive the subsequent deformation in (α+β)-the area that is not being destroyed.

In the deformation process in (α+β)-region (strain hardening) with ukonom at least 1.25 occurs simultaneously change β-grains and α-plates. They plushevaya, stretch along the direction of metal flow, are crushed. The density of structural defects as α-phase and β-phase growing. After deformation in (α+β)-region during subsequent heating to temperatures β-region is formed much more recrystallized β-grains than β-deformation. By the time of reaching temperatures of βarea β-grains have small dimensions and equiaxial. To improve the ductility of the metal in the further processing in (α+β)-field deformation in β-the area should be conducted with ukonom not less than 1.1. At temperatures of β-region in the case of long time of heating and slow cooling causes grain growth (collectively, recrystallization). For fixing structure after primary recrystallization use rapid cooling (water or air-steam mixture).

For a homogeneous globular-lamellar microstructure with no signs of borders &x003B2; -grain conduct the deformation of the workpiece in (α+β)-region with total ukonom exceeding 2,5.

Cooling at least one workpiece in the water at the final stage (α+β)-deformation prevents excessive enlargement of the individual elements of the structure.

At least one of the forging operation after heating the workpiece at temperatures of 50-80°With the lower Chamber by increasing the number of deformable α-phase promotes the formation of the microstructure, are more likely to undergo processes of globularization αphase during subsequent processing of the workpiece at temperatures of 20-40°below the temperature of polymorphic transformation of the alloy for a time, ensuring the passage of globularization α-phase. Subsequent cooling in water fixation of the resulting structures.

The use of the technological scheme described in the present invention, provides the blanks with homogeneous globular-lamellar microstructure 2-4 type.

An example implementation of the method.

The ingot with a diameter of 740 mm of titanium alloy Ti6A14V with the temperature of polymorphic transformation 990°heated to a temperature of 1200°S, had a comprehensive forging ingot by double precipitation-pulling with deformation rate of 15-30% per transaction. Then carried and heating the billet to a temperature of 1100° C. had a comprehensive forging (single sediment-drawn) with deformation rate of 30% per transaction. Cooled in air to a temperature of the shop.

Next was carried out by heating to a temperature of 950° (40°lower Chamber of Commerce). The deformation thus led to the degree of deformation of 15-30% for one transition (met one comprehensive forging and drawing). Then made the drawing of the workpiece after heating to a temperature of 1060°C. When heated undergoes recrystallization, resulting in an additional reduction and the alignment of the grains.

Next, heating is performed to a temperature of 950° (40°lower Chamber of Commerce). The deformation was carried out with the degree of deformation of 15-30% for one transition (met one comprehensive forging and two broaches). After the second drawing of the workpiece was cooled in water. Then fired heating to a temperature of 940° (50°below CCI), two pulling with the degree of deformation of 20-35% for one transition and cooling of the workpiece in the water.

Next performed heating the billet to a temperature of 955° (35°below CCI) within 6,0 hours, after which the workpiece is necessarily cooled in water. Then the billet was heated to a temperature of 950°has been drawn to the final diameter of 275 mm, after which he spent editing and cooling of the workpiece in the water.

Forged billet was trimmed to a diameter of 254 mm and was subjected to ultrasonic rear is Liu (diameter flat-bottomed reflector 1.2 mm).

The claimed method in comparison with the known ensures more homogeneous globular-lamellar microstructure (microstructure 2-4 type according to the claimed method, while by a known method - microstructure of 3-5 type) and reducing structural noise during ultrasonic testing of machined billet.

The achievement of the technical result is illustrated by the drawing, which shows the microstructure of 2-4 type (X100) billet with a diameter of 254 mm titanium alloy Ti6A14V made the claimed method.

A method of manufacturing intermediate pieces (α+β)-titanium alloys, including the operation of deforming the ingot at temperatures of β-field and combined operations deformation of the workpiece at temperatures (α+β) - β-areas, characterized in that at the final stage of deformation at a temperature in (α+β)-region of at least one of the forging operation is performed after heating the billet to a temperature of 50-80°Below the temperature of polymorphic transformation of the alloy (CCI), with the workpiece at least once cooled in water, and before deformation on the final size of the workpiece is heated to a temperature of 20-40° below CCI over time, ensuring the passage of globularization α-phase, and fixed who have obtained the structure of the cooling water, then the workpiece is again heated to a temperature of 20-40°lower Chamber of Commerce and permanently deform.



 

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8 cl, 5 tbl, 6 dwg, 4 ex

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2 dwg

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4 cl, 10 dwg

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3 cl, 1 dwg

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