Processing effects on the structure and properties of Fe based superelastic alloysThursday (17.05.2018) 14:35 - 15:00 Part of:
A comparative study concerning the evolution of the microstructure and mechanical properties following processing of two Fe based superelastic alloys, Fe41Ni28Co17Al11.5Ta2.5 and Fe43.5Mn34Al15Ni7.5 has been performed. In the latter, which is an eligible candidate for high temperature superelastic applications , the effects of substituting plus-minus 1.5 at. % Al with Ni were analysed. The ingots were axially sectioned and subjected to four thermomechanical processing steps: (i) hot rolling, with reduction degrees between 43 and 60 %; (ii) annealing; (iii) cold rolling with reduction degrees between 60 and 92 % and (iv) complex heat treatment, under protective Ar atmosphere, by means of five temperings, one solution treatment and one ageing . The microscopic evolution of grain size and grain shape following the four processing steps was monitored by optical and scanning electron microscopy and energy dispersive spectroscopy. Micro-hardness evolution, along specimen thickness, were measured and monitored during consecutive processing steps. Tensile specimens were cut by spark erosion and loading-unloading tests were performed by means of a tensile testing machine. The evolution of mechanical properties following consecutive processing steps is discussed.