Abstract
In this paper, the effects of friction and temperature on Nimonic 115 superalloy are presented during hot forging. Various contact conditions were applied including dry contact and lubricated conditions using graphite, glass and mica sheets in hot ring compression and hot compression processes. The FEM simulations were carried out to derive friction factors during hot ring compression test. An upper bound method was employed to calculate friction factor during hot compression. The microstructures of samples were also examined after hot compression tests from optical microscopic observations. The partial and full dynamic recrystallization was observed at 1100 °C and 1175 °C, respectively. It was found that a mica sheet was useful for hot forging of Nimonic 115. Its friction coefficient was found by two different methods to be approximately 0.3.

Key words
nickel base superalloy, Nimonic 115, hot compression, hot ring compression, friction coefficient, lubricant, upper bound method, dynamic recrystallization, necklace structure

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