RU2563083C1 - Method of manufacture of long-length work piece from titanium alloy - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: forging or rolling of an ingot is performed at the temperature of β-area with fabrication of a bar. The bar is cut into work pieces which are subjected to intermediate forging at the temperature of (α+β) area, mechanically processed, heated to the temperature (α+β) area and deformed. Deformation is performed by extruding in a die from heat resisting nickel alloy on the press with obtaining of bar or profile. Machining is performed by grinding of work pieces with cutting on side surface of longitudinal grooves or thread for greasing. The greasing is applied on a surface of machined work pieces and they are placed into the die from heat resisting nickel alloy. The work pieces are heated together with the die.

EFFECT: producing of long-length work pieces with the uniform regulated fine-grained structure and decrease of labour input of manufacture.

6 cl, 1 dwg, 1 tbl, 1 ex

Description

FIELD OF THE INVENTION

The invention relates to the processing of metals by pressure and can be used in the production of long billets such as rods and profiles from structural titanium alloys by isothermal extrusion.

State of the art

Rods and profiles are one of the most popular for the manufacture of parts of the power set and glider fasteners. Therefore, in their production, special attention is paid to the formation of a regulated fine-grained structure that provides a high level of mechanical properties, as well as reducing labor intensity and increasing yield on the final product.

Currently, the following methods are used in industry for producing semi-finished products (rods and profiles) from structural titanium alloys: multi-junction hot rolling or forging of ingots with subsequent cold drawing to the required size; forging an ingot onto a bar in the β- and (α + β) -regions followed by pressing in the (α + β) -regions. However, rolling and pressing usually produce large-diameter workpieces, and the cold drawing process, including multiple intermediate annealing, has a high manufacturing complexity.

From the prior art (patent US 7152448 B2, publ. 12/26/2006) there is a known method for the production of bar stocks with an ultrafine-grained structure by equal channel angular pressing (ECAP) according to the "Conform" scheme. This method allows to obtain blanks with ultrafine-grained structure, which provides a high level of mechanical properties. However, the disadvantages of this method are the need to create special equipment, low process productivity and the aim of ECAP is to grind the structure without changing the cross section of the workpiece.

A known method for producing semi-finished products from titanium alloys, including operations of smelting ingots, heating billets in recuperative heating wells, rolling ingots on blooming, rolling blooms in a crimping stand of a large mill, rolling blanks into a final profile in mill stands, cutting blanks to lengths and cooling workpieces (see. Titanium alloys. Semi-finished products from titanium alloys. Alexandrov V.K., Anoshkin N.F., Belozerov A.P. - M .: VILS, 1996, pp. 177-179). This method allows to obtain semi-finished products from titanium alloys on a rolling mill without the use of special equipment. Despite this, the disadvantages of this method are: the impossibility of obtaining the desired structure in the intermediate workpiece due to the fact that deformation at all transitions takes place in the β-region, as well as large metal losses during subsequent cutting and turning due to poor surface quality and geometry rolled rods.

Closest to the proposed invention, and taken as a prototype, is a method of manufacturing intermediate blanks from α and (α + β) titanium alloys, presented by JSC "VSMPO-Avisma" (RF patent No. 22117260, MKP B21J 1/04, publ. 27.11. 2003). The essence of the known invention is as follows: forging an ingot onto a bar in several transitions at a temperature of the β-region, intermediate forging at a temperature of the (α + β) region with a hood of 1.25-1.75, and at the final transitions, forging is carried out with a hood 1.25-1.35, which leads to the destruction of the large-angle boundaries of β-grains and a uniform structure over the entire cross section, and the final pressing at the temperature of the (α + β) region. The disadvantage of this method is the inability to obtain blanks of small diameter (the invention is directed to an intermediate blank with a diameter of 100-150 mm).

Disclosure of invention

The technical problem, the solution of which the invention is directed, is to obtain rods and profiles with a high hood (the amount of hood 50-100).

The technical result is expressed in obtaining long billets with uniformly regulated fine-grained structure (less than 10 microns), in reducing the complexity of manufacturing due to the use of isothermal extrusion, as well as in reducing the number of operations.

The specified technical result is achieved by the fact that the method of manufacturing long billets from titanium alloys includes forging or rolling an ingot into a bar in the β-region to obtain a path, cutting the bar into billets, intermediate forging at a temperature of the (α + β) region, machining the billets, heating them to a temperature of the (α + β) region and deforming, while deforming the workpieces by extruding them in a matrix of heat-resistant nickel alloy on a press to obtain a bar or profile, mechanical processing the preforms are rolled by grinding them by cutting on the lateral surface of the longitudinal grooves or threads for lubrication, grease is applied to the surface of the machined preforms and placed in a matrix of heat-resistant nickel alloy, and the preforms are heated to a temperature of the (α + β) region together with specified matrix.

It is preferable for extrusion to use a one-piece cast matrix made of heat-resistant nickel alloy.

Preferably, the extrusion is carried out by angle pressing.

Preferably, the extrusion is carried out in a hydraulic press with a heating unit.

Preferably, the extrusion is carried out with a drawing ratio of more than 50.

Preferably, the extrusion is carried out with a strain rate of 10^-3 - 10^-four from^-one.

Brief Description of the Drawings

The figure 1 presents a diagram of the process of obtaining profiles and rods.

The implementation of the invention

For the manufacture of billets, a matrix is used (Fig. 1), for example, an integral cast matrix made of heat-resistant nickel alloy with a side hole made in the form of a profile or a rod of appropriate dimensions for extruding metal. The composite matrix (figure 1) consists of a holder (1) and a backwater (3). Heated to the extrusion temperature of the original billet (4) is placed in a composite matrix, then a blank washer (2) is installed on the billet. To obtain an extrudable preform (5), deformation is carried out in the (α + β) region, preferably, provided that the metal temperature is equal to the matrix temperature with low deformation rates to prevent deformation heating. The extrusion process is characterized by a high degree of drawing and the absence of intermediate annealing, which reduces the number of necessary operations in the manufacture of blanks.

The essence of the invention is as follows:

The titanium alloy ingot is forged or rolled at a temperature in the β-region, which leads to the destruction of the cast structure of the ingot and the formation of a coarse-grained structure in the deformed semi-finished product. Cutting to measured blanks is carried out, taking into account the geometry of the matrix and the required length of the final semi-finished product.

Measured billets are subjected to comprehensive forging on a press, for example, on a hydraulic press with a heating system, with the possibility of adjusting the deformation rate according to the “draft-broach” scheme at a temperature of the (α + β) region. Forged measured billets are machined to the required diameter and longitudinal grooves or threads are applied to the cylindrical surface. Glass-lubricant is applied to the turned workpieces over the entire surface, placed in a cast matrix of heat-resistant nickel alloy and heated to the temperature of the (α + β) region. The extrusion process takes place on the press, which allows you to get a fine-grained structure with a β-grain size of less than 10 microns and a globular α-phase. The use of a hydraulic press equipped with isothermal plants allows extrusion at low deformation rates (0.05-0.1 mm / s). A feature of the extrusion process according to this scheme is a change in the direction of deformation (angular pressing). This extrusion process is preferred, but optional.

Implementation example

An ingot of VT6 alloy was rolled in the β-region onto a bar with a diameter of 100 mm. Then the bars were turned to a diameter of 90 mm. The rods were cut into measured blanks and grooves were applied to their lateral surface in the form of a thread with a pitch of 1-2 mm in order to preserve the lubricant during pressing. Further, a comprehensive forging of workpieces was carried out on a hydraulic press under isothermal conditions in the (α + β) -region by a diameter of 65 mm in order to study the structure and increase the plasticity of the workpiece.

The resulting cylindrical workpieces were turned into a diameter of 60 mm and a height of 50 mm, placed in a cast matrix of heat-resistant nickel alloy and heated to certain temperatures. Experiments were conducted at three different temperatures: T _pp - 20 ° C, T _pp - 40 ° C and T _pp - 60 ° C.

Further, the billet was extruded on a hydraulic press equipped with an isothermal installation onto a bar with a diameter of 6 mm in one operation. The strain rate was 0.1 mm / s.

As a result of the work, semi-finished products of VT6 alloy were obtained with a length of 3-5 m and a diameter of 6 mm with a regulated fine-grained structure.

The results are presented in table 1.

The table shows that, compared with the prototype, the proposed method for the manufacture of long workpieces provides a regulated structure with a grain size of less than 10 microns.

Claims (6)

1. A method of manufacturing long billets from titanium alloys, including forging or rolling an ingot at a temperature of the β-region to obtain a bar, cutting the bar into billets, intermediate forging of billets at a temperature of the (α + β) region, their machining, heating to a temperature ( α + β) -regions and deformation, characterized in that the deformation of the workpieces is carried out by extrusion in a matrix of heat-resistant nickel alloy on a press to obtain a bar or profile, the machining of the workpieces is carried out by wrapping them Chivanov slicing with the side surfaces of the longitudinal grooves or of the thread for lubrication to the surface of the machined workpieces is applied lubricant and put them in a matrix of heat-resistant nickel alloy, and heating the workpieces to a temperature of (α + β) -region produces together with said matrix. 2. The method according to p. 1, characterized in that the extrusion is carried out in an integral cast matrix of heat-resistant nickel alloy. 3. The method according to p. 1, characterized in that the extrusion is carried out by angular pressing. 4. The method according to p. 1, characterized in that the extrusion is carried out on a hydraulic press with a heating installation. 5. The method according to p. 1, characterized in that the extrusion is carried out with a drawing ratio of more than 50. 6. The method according to p. 1, characterized in that the extrusion is carried out with a strain rate of 10 ^-3 - 10 ^-4 s ^-1 .