Effects of the Number of ECAP Passes and ECAP Route on the Heterogeneity in Mechanical Properties across the Sample from Titanium VT1-0

Abstract

Titanium VT1-0 was processed by four passes of equal-channel angular pressing (ECAP) using two routes, BC and C. Pressed samples had a square section with a side length of 8 mm. Mechanical properties at tension (tensile strength, conventional yield strength and elongation) were determined at 9 points across the sample using small-size specimens, 1.5 mm in diameter, cut out along the pressing direction. Heterogeneity in the mechanical properties across the sample was determined based on the value of the variation coefficient. One can observe that heterogeneity in the mechanical properties generally tends to decrease with the number of ECAP passes.

Features of Twist Extrusion: Method, Structures & Material Properties

“…Recently a few reports on the properties and structural distribution in ECAE processed billets were published [15][16][17][18]. The uniformity of TE processing is an even more important question to be addressed as the process seems to give a non-uniform strain distribution.…”

“…Comparison of twist extrusion and equal channel angular extrusion processing. The comparison is based on data reported in [16], where authors used the same material and tests conditions. As stated earlier the estimated true strain after one TE pass is e≈1.2.…”

“…High Pressure Technology of Nanomaterials upwards while after ECAE processing they are convex downwards (especially when route B C is used) [16]. (This refers to the "surface" 3D representation of the properties distribution in a billet cross-section; so "convex upwards" means that a property in the centre is superior to the property on the periphery and "convex downwards" means that a property in the centre is lower than the same property on the periphery).…”

Distribution of Mechanical Properties by Volume in Titanium Billets Processed by Twist Extrusion

“…These undoubtedly important data make it possible to estimate the efficiency of the SPD processing, but do not show the distribution of mechanical properties across the billets. Recently a few reports on the properties and structural distribution in Equal Channel Angular Extrusion (ECAE) processed billets were published [9][10][11][12]. The uniformity of TE processing is an even more important question to be addressed as the process seems to give a non-uniform strain distribution [8,13,14].…”