TY - THES

T1 - Thermal stability and structural evolution of a modified 2XXX alloy for an engine component application

AU - Donau, Moritz

N1 - embargoed until 31-05-2027

PY - 2022

Y1 - 2022

N2 - Components for automotive application are typically characterized by sophisticated design and the use of dedicated materials, which is mainly based on the omnipresent demand to increase energy efficiency. Thus, not only resistance against environmental conditions is strongly required, but also a reduction in weight. The crank drive of combustion engines can be considered one of the most critical sections in this aspect, as high temperatures and pressures occur in combination with high dynamic loads. Pistons for serial application are typically made of casting Al-alloys featuring rather simple designs. Yet, racing application requires significantly more enhanced concepts in respect of design, manufacturing strategies, and selected materials. One novel example is the additive manufacturing (AM) route. The focus of the present work is set on the microstructural modifications of a modified 2xxx Al-alloy, specifically designed for the use in highly loaded AM-produced pistons, after thermal exposure. Thereby, the base powder and the printed piston using two different process (layer height) and heat treatment conditions [T4 and HIP-T6 (hot isostatic pressing)] is compared with a conventionally manufactured piston made of a 2xxx Al-alloy with different chemical composition. It can be shown that the precipitation behavior of the as-received powder differs from the printed and heat-treated piston by the occurrence of predominately Ti-Zr-enriched precipitates rather than the stable Al2Cu phase. The inherent anisotropy of the AM process becomes evident by the formation of areas with different precipitation sizes and distribution, independent on the printing or heart treatment conditions. Hardness measurements indicate a slight variation of mechanical properties of these areas. The modified 2xxx Al-alloy demonstrates enhanced mechanical properties after annealing treatments, with the most significant differences after 72 h and 350 °C, with remaining hardness values twice as high as the reference material. The final investigation was focused on a 3D printed piston that was subject to an engine test run, highlighting the potential for racing applications not only of the process but also the selected modified 2xxx alloy.

AB - Components for automotive application are typically characterized by sophisticated design and the use of dedicated materials, which is mainly based on the omnipresent demand to increase energy efficiency. Thus, not only resistance against environmental conditions is strongly required, but also a reduction in weight. The crank drive of combustion engines can be considered one of the most critical sections in this aspect, as high temperatures and pressures occur in combination with high dynamic loads. Pistons for serial application are typically made of casting Al-alloys featuring rather simple designs. Yet, racing application requires significantly more enhanced concepts in respect of design, manufacturing strategies, and selected materials. One novel example is the additive manufacturing (AM) route. The focus of the present work is set on the microstructural modifications of a modified 2xxx Al-alloy, specifically designed for the use in highly loaded AM-produced pistons, after thermal exposure. Thereby, the base powder and the printed piston using two different process (layer height) and heat treatment conditions [T4 and HIP-T6 (hot isostatic pressing)] is compared with a conventionally manufactured piston made of a 2xxx Al-alloy with different chemical composition. It can be shown that the precipitation behavior of the as-received powder differs from the printed and heat-treated piston by the occurrence of predominately Ti-Zr-enriched precipitates rather than the stable Al2Cu phase. The inherent anisotropy of the AM process becomes evident by the formation of areas with different precipitation sizes and distribution, independent on the printing or heart treatment conditions. Hardness measurements indicate a slight variation of mechanical properties of these areas. The modified 2xxx Al-alloy demonstrates enhanced mechanical properties after annealing treatments, with the most significant differences after 72 h and 350 °C, with remaining hardness values twice as high as the reference material. The final investigation was focused on a 3D printed piston that was subject to an engine test run, highlighting the potential for racing applications not only of the process but also the selected modified 2xxx alloy.

KW - Additive Fertigung

KW - Aluminium

KW - modifizierte 2xxx Al-Legierung

KW - Aluminiumlegierung

KW - Thermische Stabilität

KW - Additive Manufacturing

KW - Thermal Stability

KW - Aluminum

KW - modified 2xxx Al-Alloy

M3 - Master's Thesis

ER -