Continuous Extrusion Forming Research Articles

Effect of continuous extrusion on the microstructure and mechanical properties of a CuCrZr alloy

A Cu–0.16Cr–0.12Zr alloy with an initial grain size of about 400μm was extruded by continuous extrusion forming (CEF), where severe plastic deformation and precipitation process occurred. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to examine the microstructure and morphology of the precipitates. Experimental results show that a notable grain size reduction to sub-micron scale is obtained through continuous dynamic recrystallization and precipitates maintain a fine and disperse morphology after the CEF process. These two features are considered as the effective ways to improve the strength and ductility of the CuCrZr alloy after cold deformation and subsequent aging process without a significant decrease of electrical conductivity.

Continuous extrusion and rolling forming velocity of copper strip

A new copper strip production technology combined with continuous extrusion and rolling technology was proposed. The roll velocity must first be matched with the continuous extrusion velocity to achieve continuous extrusion and roll forming. The bite condition of continuous extrusion was determined, and the compatibility equation between the roll velocity and parameters such as the extrusion wheel velocity, reduction, and strip size was established through mechanical by plastic theoretical calculations. The finite element model of continuous extrusion and rolling was then established by using the TLJ400 continuous extrusion machine with a roll diameter of 200~mm. The relationship between the continuous extrusion and rolling velocities was determined through numerical simulations by software DEFORM-3D, and the accuracy of compatibility equation of velocity was verified.

Grain Refinement of Magnesium Alloys by CONFORM: A Continuous Severe Plastic Deformation Route?

Effective grain refinement through equal channel angular pressing (ECAP) for magnesium (Mg) alloys has been demonstrated by many researchers. Although with the capability to achieve superplasticity, the batch mode nature of this method and the required repetitive processing to attain ultrafine grained structure have prohibited it from being widely used in large-scale industrial production. In this study, a well-established metal forming method – the continuous extrusion forming (CONFORM) process – was employed as a severe plastic deformation route to refine the microstructure of Mg alloys. Cast Mg-3%Al-1%Zn (AZ31) rods were used as the feedstock and the cast structure (grain size of ~150 microns) was refined to ~1 micron after one pass CONFORM extrusion. Uniaxial tensile tests of the as-extruded samples were conducted at a temperature of 473K and an elongation of ~200% was achieved under a strain rate of 1×10-4 s-1. The significant grain refinement effect was attributed to the severe shear deformation occurred during the CONFORM process, which is very similar to ECAP but with even higher effective strains. The most important advantage of CONFORM over ECAP is that the former is a continuous route, so it is able to produce long products. It was also shown that CONFORM could be an additional forming method for Mg alloys to conventional rolling, forging and extrusion.

FVM Simulation of the Effect of Preventing Ring Structure on Continuous Extrusion Process

Continuous extrusion is an advanced process for manufacturing copper bus-bar while preventing ring is an important factor affecting forming. Due to the severe plastic deformation, FE simulation of continuous extrusion extending deforming is inaccurate and inefficient because of frequent remesh. Based on finite volume method (FVM) which can avoid re-mesh effectively, this paper simulates continuous extrusion forming, and analyzes the effect of different preventing ring structure on metal flowing velocity. The results show that: preventing ring with the curve transitional surface is beneficial to metal uniform flowing than that with the plane transitional surface; As radius of preventing ring increases, the metal flow rate of the sides is faster than the middle part; As opening width of preventing ring increases, the dead metal zones become smaller in the middle area.

Microstructure of AZ31 Magnesium Alloy Produced by the CONFORM Process under Different Extrusion Wheel Velocities

It is widely known that the continuous extrusion forming (CONFORM) process can produce ultra-long seamless products of various cross-sections for aluminum, copper and their alloys. In this paper, the continuous extrusion of AZ31 magnesium alloy is achieved. The effect of extrusion wheel velocity on microstructure of extrusions is investigated. The results indicate that grain refinement is realized during CONFORM process. As the extrusion wheel velocity increases, the grain size at the center of a cross section perpendicular to the extrusion direction of an extrusion increases, and the grain structure tends to become uniform in the surface region.

Production of Very Fine Grained Mg–3%Al–1%Zn Alloy by Continuous Extrusion Forming (CONFORM)

AbstractVery fine grained (∼2 µm) Mg–3%Al–1%Zn alloy rods are produced using an industrial continuous extrusion forming (CONFORM) machine. Cast rods (grain size ∼150 µm) are utilized as the feedstock and significant grain refinement is achieved in a single extrusion process. Tensile elongation of about 200% is achieved at 473 K using the extruded sample. This demonstrates the potential application of CONFORM as a continuous severe plastic deformation process to produce very fine grained metals to attain superplastic properties.

Numerical Simulation on Conform Process of Aluminum Alloy Rectangular Hollow Conductor

In the investigation, the continuous extrusion forming (CONFORM) process of aluminum alloy rectangular hollow conductor has been studied by three-dimensional finite-element method based on Software DEFORM-3D. The rigid-viscoplastic constitutive equation was employed in the model. Distributions of velocity field, strain field, stress field and temperature field were obtained in the forming process. The results will give effective guidelines to optimize the processing parameters and to select, the die structure and die materials.

The experimental simulation of deformation behavior of metals in the conform process

In this paper, the deformation behavior of the conform continuous extrusion forming) process has been studied by experimental simulation. In the experimental arrangement, the frictional force can be taken as the driving force that effects the plastic deformation of the metal through the die. A Moiré method is utilized for investigating the plastic flow of the metal in the experimental simulation. It is found that an intense internal shear band (IISB) exists in the plastic deformation zone. The existence of the IISB can not only mitigate the inhomogeneity of plastic deformation, but can also improve the attainable level of plastic deformation of the metal.

Conform—A New Concept for the Continuous Extrusion Forming of Metals

The paper describes a new continuous extrusion forming process, for metals, which is particularly applicable in the wire, section, and tube manufacturing fields. The principle of the process is based on the mechanical friction which exists between a billet and its container in conventional extrusion. If the container is rectangular in cross section and three sides are formed as a groove in a rotating wheel, with the fourth side forming a stationary shoe fitting against the outside of the wheel, then rotation of the wheel will carry the billet along with it. If a stop with die orifice is sized to fit the groove and is fixed to the shoe, then as the billet is forced against the die, extrusion can occur. The development of the process from a laboratory bench top model for lead wire, to a powered experimental machine capable of continuously extruding aluminium wire through ratios of 40:1 is described in the paper. The possibilities for future development are discussed and some guide is given to the possible size and capacities of projected machines.