THERMAL AND MECHANICAL RESPONSE OF METAL PIPES DURING HOT EXPANSION: AN EXPERMANTAL AND NUMERICAL STUDY

Аннотация

The present work examines how tube-wall thickness and conical die semi-angle govern the thermally assisted expansion response of AA6061 aluminum and BR6040 brass tubing, evaluating two wall gauges (1.5 mm and 2.0 mm) in combination with three die semi-angles (15°, 20°, and 30°). Expansion loads were quantified under both ambient and elevated-temperature conditions to isolate the role of thermal input in governing material response. Across every geometric and material combination examined, forming at elevated temperature was found to substantially lower the peak expansion load relative to the cold condition, with reductions spanning 24–54% depending on alloy, gauge, and die geometry. As a general trend, greater wall thickness raised resistance to plastic flow and consequently demanded higher forming loads, whereas heating to 450 °C for the aluminum alloy and 700 °C for the brass alloy markedly enhanced material formability and lowered flow resistance. Among the two alloys, AA6061 displayed a comparatively steeper load reduction under thermal loading than BR6040, an effect that became more pronounced at larger die angles. These outcomes underscore the capacity of hot expansion to both diminish forming loads and promote greater ductility. In parallel, finite element predictions generated in ABAQUS closely tracked the experimentally measured trends, lending confidence to the numerical model's ability to capture expansion response across the full range of thicknesses and die angles investigated.