Hot ductility and structure of the cast alloy KhN60KVMYuB during high speed deformation

Abstract

1. The high-temperature ductility of the dispersion-hardening nickel alloy KhN60KVMYuB at a deformation rate corresponding to that occurring during extrusion is adequate in the temperature range 1040–1190°C. Below 1040°C the ductility is low due to the presence of a large volume fraction of γ′-phase in the structure. 2. Deformation of the cast alloys at 1100–1190° is accompanied by dynamic recrystallization, as a result of which, in the absence of a second phase, a fine grained structure is formed (including a "necklace" type of structure) which posesses high ductility. 3. The temperature range of high ductility coincides with the range of dynamic recrystallization in the alloy resulting in the formation of grains with an average size of less than 100 μm. 4. Dynamic collective recrystallization leads to the formation of a coarse-grained structure with grain boundaries of low mobility. This structure has low resistance to the initiation of interfacial cracks, and their growth under applied load.