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Continuous extrusion of commercially pure titanium GRADE 4

Palan J., Taboada J. V., Kubina T., Malecek L., Hodek J.

Journal of Achievements in Materials and Manufacturing Engineering

2015

Vol. 69, nr 1

33--37

Purpose: Continuous extrusion of metals using Conform™ machine is used to introduce severe plastic deformation and to improve mechanical properties of metals by reducing their grain size. This paper describes a development of a continuous extrusion sequence for Ti grade 4 in the CONFORM 315i machine. Design/methodology/approach: The influence of material flow conditions on the surface quality of final extruded rods was analyzed with the FEM-based DEFORMTM software. Findings: During the development, several process parameters were varied, such as the die chamber temperature and the extrusion velocity. Research limitations/implications: The goal was to conduct the experiment at the lowest possible temperature in order to achieve a maximum strain hardening effect. The material’s mechanical properties and its flow through the die chamber were studied. The homogeneity of the material flow and the surface quality of final rods were then optimized. Originality/value: The effort led to improvements in the analytical model used in the FEM simulation so that the surface quality can now be optimized more efficiently.

FEM simulation of open die forging of a plate from material NIMONIC 80A in DEFORM 3D

Polakova I., Duchek M., Malecek L.

Archives of Materials Science and Engineering

2014

Vol. 66, nr 1

31--36

Purpose: This article presents results of a three-dimensional FEM-simulation of open die forging of a plate from material NIMONIC 80A. The FEM-simulation was carried out in DEFORM 3D Multiple Operation. Design/methodology/approach: The open die forging simulation contains many sequence operations, each single stroke and displacement of dies had to be modelled. The FEM-simulation of the open die forging process was set in accordance with real process conditions. Findings: The main effect on the crack initiation was the decrease in temperature on a edge of the plate. The real forgings show transverse cracks on the surface which starts on edges of the plate during forging. A good agreement between the simulation and experiment results was observed. Research limitations/implications: The plastic behaviour of material NIMONIC 80A was defined by means of strain hardening data which was obtained on the basis of measured data from Rastegaev compression test. The desired final thickness of the plate was reached by two procedures to study the effect of an amount of a reduction. The first procedure comprised 8 reduction passes with three reheatings, and second procedure comprised 10 reduction passes with four reheatings. The data evaluation of crack initiation in the FEM-simulation was carried out by tensile tests on the specimens. Originality/value: This article describes the FEM-simulation of open die forging process that was set in accordance with real process conditions. The aim of this simulation was to analyze the effect of an amount of a reduction on crack initiationon a real plate and to suggest the optimization of the process.