Thesis

Incremental equal channel angular pressing at elevated temperatures of Al 5083 and follow-up backward micro-extrusion of components

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Awarding institution
  • University of Strathclyde
Date of award
  • 2026
Thesis identifier
  • T17653
Person Identifier (Local)
  • 201160254
Qualification Level
Qualification Name
Department, School or Faculty
Abstract
  • The demand for micro products has been continuously increasing over the years. Many industries, including telecommunications, automotive, and medical fields, need small and precise micro parts. However, the main challenge lies in manufacturing these microparts using the most suitable process. One promising option is backward micro-extrusion, which is characterised by low material consumption, low force requirements, and high production rates compared to forward micro-extrusion. Nevertheless, the formability and surface finish of the micro parts depend greatly on the condition of the material and the process parameters. This study focuses on producing miniature conical pins, and two important research questions arise. The first concerns which types of materials produce better final conditions of microparts, while the second examines the effects of processing backward micro-extrusion at elevated temperatures on product quality. The answers to these questions involve addressing the key challenges, determining the suitable material condition, which is ultrafine-grained (UFG) materials, and identifying the optimal process temperature in microforming. The Incremental Equal Channel Angular Pressing (I-ECAP) method was used to produce UFG Al 5083 material. It was processed at 200 °C using route BC and a die with a 90° channel angle, using the as-received Al 5083. For backward microextrusion, the process parameters included temperatures (RT, 200 °C, and 250 °C), a punch displacement of 1.0 mm, and a process time of 200 s. UFG structures were successfully produced with average grain sizes of 0.49 µm and 0.45 µm after four and eight passes of I-ECAP, respectively. The compression yield strength of UFG Al 5083 was reduced by about three times as the testing temperature increased from 200 °C to 250 °C. Consequently, the height of the conical pins achieved ranged from 80% to 100% of the cavity height for all specimens at 250 °C. The average height of conical pins at 250 °C was around 1.5 times higher compared to those at 200 °C. The results confirmed that backward micro-extrusion at elevated temperatures using UFG materials produced better filling, improved surface finish, and a lower extrusion load compared to coarse-grained materials. This study contributes new knowledge on the relationship between grain size and temperature in relation to the microforming behaviour of Al 5083. The combination of I-ECAP and backward micro-extrusion presents a novel approach to producing high-quality microparts.
Advisor / supervisor
  • Rosochowski, Andrzej
  • Qin, Y. (Yi)
  • Xie, Wenkun
Resource Type
DOI
Date Created
  • 2025

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