Effect of Annealing Heat Treatment on Fatigue and Corrosion Performance of Nickel Aluminum Bronze Alloy

Nickel aluminum bronze alloys are widely used in production of propellers and other components in marine applications. In this study, effect of heat treatment on mechanical properties, corrosion behavior and fatigue performance of nickel aluminum bronze was investigated. To study the mechanical properties, hardness and tensile tests were carried out on standard specimens. The corrosion resistance of these samples was evaluated in ۳.۵% NaCl solution by potentiodynamic tests. Samples were fatigue tested using four-point rotating bending fatigue machine. The surface of the specimens were also examined by scanning electron microscopy after the corrosion, tensile and fatigue tests. Experimental results show that heat treatment has significant effect on microstructure. The hardness of  alloys slightly decreased (less than ۲%) after annealing process. The hot-roll sample showed better tensile strength and yield strength than the annealed specimen, although the elongation in hot-roll sample was about ۷% less than the annealed sample. Corrosion behavior of the annealed sample was generally somewhat better than hot-rolled.  Fatigue test results showed that the as-received alloy with a higher percentage of spherical κ phase had better fatigue performance than the annealed condition; the fatigue strength of the as-received specimen was about ۱۰۰ MPa higher than that of annealed sample. Microscopic examinations confirmed results of the fatigue tests.

Keywords:

Nickel aluminum bronze , Fatigue strength , Corrosion behavior , Mechanical properties , Anneal heat treatment , برنز آلومینیوم نیکل دار , استحکام خستگی , رفتار خوردگی , خواص مکانیکی , عملیات حرارتی آنیل.