EXTRUSION TECHNOLOGY
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ANALYSIS OF SOME PROCESSES OF INTENSIVE PLASTIC DEFORMATION (IN CONFORMITY WITH INDUSTRIAL CONDITIONS)
The present paper covers both well-known and new techniques of intensive plastic deformation applied for an increase in the number of microslips and refining of grain size in a structure of aluminium alloys, to obtain...
Vadim L. Berezhnoy , All-Russia Institute of Light Alloys (VILS Stock Co.), RussiaAbstract
The present paper covers both well-known and new techniques of intensive plastic deformation (IPD) applied for an increase in the number of microslips and refining of grain size in a structure of aluminium alloys to obtain a dramatic improvement in ductility and strength. The results of studies and the possibility of integration of IPD processes in commercial technologies have been evaluated at VILS Stock Co. and background information with respect to the processes has been discussed. Among these processes are equal-channel angular and screw extrusion of billets, extrusion with alternate shear stresses transferred to a billet from the die and container. Main directions of the use of IPD in extrusion technology are determined and discussed.
Introduction
Processes of direct and indirect extrusion are still basic in extrusion technology, although researchers offered quite a number of new extrusion techniques in the 50 – 80th of the 20th century (1 –4).
Variants of new friction-assisted indirect extrusion (FAIE) (5), Conform (3, 6), hydrostatic extrusion (2, 7) and isothermal extrusion (for example, (8)) were brought to commercial usage.
Conform technology is a non-alternative effective addition to the basic technologies, therefore the field of its world application for production of small-size extruded components in soft metals and alloys is broadening rather quickly.
The other mentioned technologies, by the way, alternative to the basic technologies and more intensive in production, develop slower. It is possible that a part of them is a kind of “reserve for the future”, though it is hushed up in (9).
However, metal flow and deformation, in the case of the basic extrusion processes, especially in the case of direct extrusion without the use of lubricants (Fig. 1, B, C), have a non uniform character. This obstacle, in particular, limits extrudability and a hardening level of hard aluminium alloys (5).
Meanwhile, various techniques and conditions for intensive plastic deformation (IPD), which are mainly in the stage of metallophysical simulation, are put forward in Byelarus, Russia, the USA, Germany and in most other economically developed countries in last 10 – 15 years.
IPD process is, as a rule, multiple. It results in drastic development of microslips and refining of a grain structure within a range up to nanosizes (≤ 0.1 μm). If such strain effect (energy of friction, torsion, shifting are used) is obtained (4) and certain types of thermomechanical treatment are used, general basis for attainment of high levels of ductility and service strength of components will be created (see, for example, a number of papers in the journal of Russian Academy of Sciences “Metally”, 2004, Nbrs 1 and 2). It is urgent for extruded semiproduct production.
The present analytical work carried out at VILS Stock Co. evaluates processes shown below in terms of suitability and readiness to industrial realization, including the basic extrusion technology. The processes are as follows:
a) equal-channel angular pressing of billets via simple shear;
b) screw pressing of billets with saving of initial shape and size;
c) direct extrusion of billets via alternate shear stresses transferred to a billet from the die;
d) pre-pressing operation - extrusion via alternate shear stresses transferred to a billet from the container.
These processes are discussed taking into account two possible uses in the industry:
- production of “intermediate” billets with improved ductility for effective deformation at subsequent extrusion and forging operations, etc. (a, b, d);
- production of semiproducts and components with a high level of strength properties (a, d).
PROPERTIES OF 2XXX ALUMINUM EXTRUDED RODS BOTH IN T3 AND T8 TEMPERS
Extruded products made from 2XXX aluminum alloys nowadays are used for various applications...One of the most common semi product made from these alloys are rounded extruded rods...
Igor Duplančić, Jere Prgin, Zoran Bračić, Siniša JunakovićFaculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, University of Split, Croatia, TLM Inc., Croatia
Abstract
Extruded products made from 2XXX aluminum alloys nowadays are used for various applications. That is because of fact that this series of aluminum alloys have many specific features related to their excellent mechanical properties. One of the most common semi product made from these alloys are rounded extruded rods. They are widely use as a row material in automated machining processes. The roundness of these rods, among the other factors, is required within narrow tolerances. Production of rods from this aluminum alloys is connected with several mutually connected metal forming and thermal treatment processes. In order to increase production of these semi product many extruders prefer to use multi holes extrusion dies. The number of holes depends on rods diameter and available container of the extrusion press. This paper describe the procedure for manufacturing rods from alloys 2007 T3 and 2011 both in T3 and T8 tempers. For this production, a solid die with 2 holes was designed and manufactured. Extrusion was performed on horizontal 25 MN extrusion press. Rods from 2007 were cold drowned to final dimension of 28 mm and those from alloy 2011 to diameter of 27 mm. All extruded rods were thermally treated to appropriate temper. Both dimensional and mechanical properties after each stage were analyzed. Result of these investigations could be useful for industrial practice.
EXPERIMENTAL STUDY OF LONGITUDINAL WELD-SEAM PROPERTIES IN HOLLOW EN-AW 6060 AND EN-AW 6082 ALUMINIUM ALLOY EXTRUSIONS
...For the successful application of structural extruded products, the mechanical integrity of the longitudinal weld seams is thus of paramount importance.
This paper presents the results of laboratory extrusion trials with the EN-AW 6060 and EN-AW 6082 aluminium alloys...
A.J. den Bakker, W.H. Sillekens, E. MeijerscNedal Aluminium B.V. - TNO Science and Industry - Netherlands Institute for Metals Research - The Netherlands
Abstract
Longitudinal weld seams in hollow aluminium extrusions are formed when the metal streams flowing around the mandrel in the die are rejoined through a process of solid-state bonding. Contrary to transverse weld seams – resulting from the billetto- billet transition – longitudinal weld seams occur along the entire length of the extrusion and thus cannot be eliminated from the product. For the successful
application of structural extruded products, the mechanical integrity of the longitudinal weld seams is thus of paramount importance.
This paper presents the results of laboratory extrusion trials with the EN-AW 6060 and EN-AW 6082 aluminium alloys in which tubular extrusions were produced using a porthole die with a mandrel supported by three legs. The extrusions were evaluated by means of a tube expansion test in order to relate weld-seam quality (ductility) to material and processing conditions. In addition, metallographic analysis
was performed to link microstructural features to the performance of the weld seams.
The extrusion trials were supported by finite element simulations for modelling material flow and estimating the local quantities that govern the solid-state bonding
process.
In line with industrial experience, results show that the weld-seam quality in alloy EN-AW 6082 is much more critical than in alloy EN-AW 6060. Further, differences in ductility appear for the former alloy along the length of the section, with the weld seams being the predominant locations of failure. Between the alloys, pronounced differences in microstructures of the extrusions exist; yet, metallurgical
bonding appears to be present for both under the investigated processing conditions.