Abstract: To avoid strength damage and improve the service life of LNG aluminumplate-fin heat exchangers, the tensile fracture mechanism of their aluminum plate-fin structures atroom/low temperature is studied using axial tensile testing and scanning electron microscope observation. The result shows that, compared to mechanical properties at room temperature, the yield limit of plate-fin specimens atlow temperature increases by 42.6%, the tensile strength increases by 48.9%, and the strain increases by 27.8% during failure. The fracture trend of plate-fin specimens at room/low temperature conditions primarily involved crack propagation from the fin root and vice versa. The overall fracture morphology of cleavage sections and dimples account for a large area of fracture surface. However, the morphology of cleavage sections is observed with high distribution at low temperature, and the plastic morphology accounts for a small area of fracture surface. The fracture of plate-fin specimen at room temperature is mainly located in the brazing zone, whereas the fracture at low temperature is confined to the brazing zone. Therefore, the fracture of the aluminum plate-fin structure in the brazing zone can be avoided by improving the brazing process of the aluminum plate-fin structure and increasing the solder in the brazing zone.

Key words: aluminum plate-fin heat exchanger, tensile test, fracture mode, morphological characteristics, low temperature, fracture mechanism