Effects of toolhead size on the heat generation and material flow behaviors in solid state friction rolling additive manufacturing

Abstract

As a key part of solid-state friction rolling additive Manufacturing (FRAM), the toolhead is used to generate heat and deformation through friction with the feed material to form a deposit, and its geometric size directly affects the formation of the FRAM plastic zone; however, to date, no in-depth studies have been conducted. In this study, the effects of toolhead diameters (25, 50, and 100 mm) on the temperature history, material flow, and mechanical properties of the deposited samples are investigated via thermocouple measurements, optical microscopy, and mechanical property tests. The results indicate that, with the increase in toolhead diameter from 25 mm to 100 mm, the area of the interaction zone between toolhead and strip increases from 138 mm2 to 274 mm2, peak temperature increases from 522.3 °C to 559.8 °C, the material flow distance in the plastic zone increases from 7.03 mm to 16.6 mm, and the deposition height decreases from 2.4 mm to 1.2 mm. Regardless of the chosen toolhead size, defect-free and high-performance deposited materials can be obtained by optimizing the process parameters. The mechanical properties of deposited 6061 via a 100-mm toolhead are optimal, and the microhardness, tensile strength, and elongation of the deposited material are 66 HV, 234.7 MP, and 28.3 %, respectively. This study provides a basis for the selection and optimization of toolhead size in the FRAM process.

Keywords

• Aluminum alloy
• Additive manufacturing
• Solid-state
• Friction stir welding
• Toolhead size