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New method of calculating the equal channel angular extrusion pressure

Spuskanyuk V., Davidenko A., Gangalo A.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

2008

z. 73 [253]

257-260

New method of calculating the equal channel angular extrusion (ECAE) pressure is introduced. Calculation of the pressure is produced by using friction factor of Siebel. This method of pressure calculation is proposed for ECAE of shaft billets and for the equal-channel angular hydroextrusion.

Finite element investigations of friction condition in equal channel angular extrusion

Son I. H., Jin Y. G., Im Y. T.

Journal of Achievements in Materials and Manufacturing Engineering

2006

Vol. 17, nr 1-2

285--288

Purpose: This study concentrates on the investigation of contact phenomenon at the interface between dies and the workpiece in terms of material flow and forming load requirement. Design/methodology/approach: The numerical simulations of an equal channel angular extrusion (ECAE) with a CP-Ti Gr-1 cylindrical specimen were carried out by applying the mixed finite element formulation with tetrahedral elements under the non-isothermal condition. Compression test was used for determination of the material data. The change of contact conditions during remeshing was also investigated in terms of variation of load requirements and volume losses after remeshing. In order to validate the numerical algorithm proposed, simulation results were compared with the experimental data. Findings: It was found that the forming load simulated was very sensitive to the contact condition of the workpiece with the channel. The current investigation clearly showed the importance of proper handling of boundary conditions to improve the solution accuracy. Research limitations/implications: Further applications of the proposed scheme are required. Practical implications: The new numerical scheme will be beneficial in better understanding the deformation mechanics of the ECAE. Originality/value: New contact algorithm to solve ECAE was developed to reduce the volume loss and load requirement after remeshing.

Właściwości mechaniczne nanokrystalicznego żelaza otrzymanego w wyniku dużego odkształcenia plastycznego

Suś-Ryszkowska M., Pakieła Z., Valiev R.Z., Wyrzykowski J.W., Kurzydłowski K.J.

Inżynieria Materiałowa

2003

R. XXIV, nr 2

59--63

Do uzyskania nanokryształów Fe wykorzystano duże odkształcenie plastyczne. Żelazo armco silnie odkształcono (epsilon dsim 12) dwiema metodami; skręcania pod wysokim ciśnieniem (HPT) oraz przeciskania przez kanał kątowy (ECA). Zbadano strukturę i właściwości mechaniczne odkształconych próbek. Uzyskano mikrostruktury o średniej wielkości ziarna mniejszej o trzy rzędy wielkości (ok. 100 nm) od stanu wyjściowego (ok. 100 mikrometrów). Wartości parametrów wytrzymałościowych, określonych w próbie rozciągania, wzrosły kilkakrotnie w stosunku do stanu wyjściowego zarówno po procesie HPT, jak i po procesie ECA. Uzyskane struktury różniły się względną liczbą granic szerokokątowych.

Over the past few years materials subjected to severe plastic deformations became the subject of scientific work as construction materials with ultrafine-grained, nano-crystalline microstructure. The interest in this type of materials is stimulated by their specific properties especially increased yield stress. The present work focuses on structure and properties of Armco iron after severe plastic deformation. The investigations were conducted on samples subjected to equal channel angular extrusion (ECA) and high pressure torsion (HPT) processes. Employed deformation methods led to obtaining of nano-grained iron microstructure. The deformation method has some effect on both size and shape of grains. Also certain evidence has been collected that the deformation path also influences the character of boundaries between neighbouringcrystals. The iron investigations performed prove that due to severe plastic deformation (epsilon log=12) the yield stress, ultimate tensile strenght (UTS), nano- and microhardness increase by several times in comparison to the initial state. The properties of severely deformed material depend on deformation path. We obtained different values of mechanical properties for ECA and HPT method instead of the same value of real strain. It can be connected with relatively different number of low-angle grain boundary.