The method of combination of intensive plastic deformation of workpieces
The invention relates to a pressure treatment of metals to improve the physico-mechanical properties, in particular in the manufacture of semi-finished titanium or other metals. In the method of combination of intensive plastic deformation of the workpieces is carried out in the following sequence: deformation by torsion in the screw channel, then equal channel angular extrusion, the billet is additionally subjected to low-temperature annealing stress relief. Provides improved uniformity of physical and mechanical properties of machined metal with a significant simplification of processing. 1 C.p. f-crystals, 1 Il., 1 PL.
The invention relates to a pressure treatment of materials to improve the physical-mechanical properties, in particular in the manufacture of semi-finished titanium or other metals.
Known methods of treatment of metals to improve their properties, in particular due to the formation of ultrafine-grained structure (UMP). These methods require extensive plastic deformation of the workpieces. For example, severe plastic deformation perform vs the th two intersecting channels (RF patent No. 2128055, MKI In 21 25/00, publ. 27.03.99 year).
Know the use of hydro-mechanical pressing with torsion by repeated transmission prismatic billet through a die with a screw channel with the aim of obtaining large plastic shear deformation of materials (I. E. Beygelzimer and other New schemes accumulation of large plastic deformations using hydroextrusion. Physics and technology of high pressure, 1999 T. 9, No. 3, S. 109).
Known methods of intensive plastic deformation, allowing to improve the strength characteristics of the processed material, lead to a decrease of plasticity. This is unacceptable for use in a number of critical structures, where the characteristics of plasticity is particularly important.
Closest to the proposed method is a combination of intensive plastic deformation, combining CGS-pressing and deformation of the torsion provided by the rotation of the workpiece in a horizontal channel through gears (Uteshev Gulf, Enikeev F. U., Latvian centuries, Petrov E. N., Valitov Century A. Thermomechanical processing for the formation of ultrafine-grained structure by severe plastic deformation. Abstracts of the international con the achievement of a homogeneous plastic deformation and, accordingly, the homogeneous properties of the workpieces due to the fact that in the process of continuous deformation of the angle of intersection of the channels during the rotation of the movable part of the matrix with a horizontal channel varies from 90 to 180°. Accordingly, the accumulated strain along the length of the workpiece while continuously pressing will be heterogeneous. More homogeneous deformation in this way can be obtained by reducing the speed of deformation and increasing the number of revolutions of the movable part of the matrix. However, reducing the pressing speed significantly reduces performance. The speed increases, the matrix also has its physical limits, primarily associated with deformational heating of the workpiece, resulting in recrystallization of the structure and loss of strength of the workpieces, or to the destruction of the pieces (slice) in the plane of rotation due to the high intensity of deformation. In addition, the technical implementation of the method causes serious technical difficulties in ensuring precision in the plane of the pair of the movable part of the matrix and fixed in the conditions of high pressure and temperature.
The objective of the invention is to improve the uniformity of physical and mechanical properties handling the MD combined intensive plastic deformation of workpieces, includes screw extrusion and equal channel angular pressing, in which unlike the prototype deformation of the workpieces is carried out in the following sequence: deformation by torsion in the screw channel, then equal-channel angular pressing.
Intense deformation leads to high internal stresses, which reduce technological plasticity during pressing. With the aim of relieving internal stresses in the workpiece material, arise in the multi-cycle treatment, and improving the technological plasticity carry out inter-cycle low-temperature anneals.
During the extrusion of the billet through the spiral channel matrix, she experiences intense shear deformation mainly in cross-section, which is subsequent CMR-pressing homogeneous intensive bulk shear deformation. Processing the workpiece material in the sequence leads to the next effect. During a full cycle of pressing the material of the workpieces reduces the size of the structure, and the proposed sequence leads to a more isotropic structural condition. This is due to the fact that less dnorm when RKU-pressing, which smoothes the resulting heterogeneity after torsion, both in structural terms and in obtaining a more uniform properties. Return sequence result in the imposition of more inhomogeneous state of a homogeneous, which is recorded in the billet after extrusion. While all known ways of handling pressure show that the values of the specified characteristics of the material in different areas of the workpiece are significantly different.
The method is as follows.
To clarify the essence of the invention in the drawing schematically shows a matrix with two intersecting angle f channels. The vertical channel 1 is screw with a constant along the axis of the section and with the changing height of the channel, the angle of the helix to the axis of extrusion, having a value of zero at the initial and end sections.
Prismatic titanium billet alloy VT1-0 in a well-annealed coarse-grained with grain size of 15-20 microns is placed in a lead-in portion of the matrix with a spiral channel through which the workpiece displacement, followed by passing it through a horizontal channel 2. Due to the fact that the cross section of the spiral channel, perpendicular to the axis of extrusion, risovanie to accumulate intense deformation and work hardening of the workpiece, and uniform structure processing.
After the plastic deformation of the workpiece is cooled to room temperature. Then it is subjected to the edit processing for removal of the defective layer.
To remove the internal stress of the workpiece optionally can be subjected to low-temperature annealing. This is needed in case of multiple passes through the above-described method.
Took the original gorjachekatanuju harvesting of commercially pure titanium grade VT1-0 in the form of a rod section 25×25 mm and a length of 100 mm Rod was subjected to the treatment according to the procedure described in 3 passes, resulting in the achieved degree of deformation e=8.
After editing and processing for removal of the defective layer have implemented the control parameters and mechanical properties.
The averaged results of the mechanical tests on 3 samples are summarized in table. For comparison, the data after processing screw pressing.
As seen from the obtained results, the proposed method of processing metals can significantly improve the strength and ductility of the workpiece material, achieving uniformity of structure and isotropy t the ula inventions
1. The method of combination of intensive plastic deformation of workpieces, comprising a screw extrusion and equal channel angular pressing, characterized in that the deformation of the workpieces is carried out in the following sequence: deformation by torsion in the screw channel, then equal-channel angular pressing.
2. The method according to p. 1, characterized in that the workpiece is additionally subjected to low-temperature annealing for stress relief.