Yoichi Takizawa 1, Kyohei Watanabe 2, Takahiro Kajita 2, Kosei Sumikawa 2, Takahiro Masuda 2, 3, Manabu Yumoto 1, Yoshiharu Otagiri 1 and Zenji Horita 2, 3
1 Technology Department, Nagano Forging Co., Ltd
In this study, high-pressure sliding is combined with incremental feeding so that a severely deformed area is enlarged without increasing the machine capacity. With this combined process (called the incremental feeding high-pressure sliding: IF-HPS), a sheet sample is lateraly fed every after sliding under high pressure. The IF-HPS process was applied to a Ni-based superalloy (Inconel 718) and a Ti-6Al-7Nb alloy (F1295) for grain refinement. The applicability of the IF-HPS process is examined with the advent of superplasticity through the grain refinement. Vickers microhardness measurement shows that the hardness is higher in the area of the second pass than the first pass for both Inconel 718 and F1295 but the hardness increase is more prominent in the area where the second passes is superimposed on the first passparticularly for the Inconel 718. After tensile testing, superplastic elongation more than 400% appears in the superimposed areas of both Inconel 718 and F1295. For the F1295 alloy, the area of the second pass also exhibits a suplerplastic elongation of 400%. Analysis by finte element method (FEM) reveals that strain introduced by outwardflow from the severely deformed area is sensitive to friction coefficient between the sample and anvil outside of the flat contact area. The strain due to this outwardflow conributes to the grain refinement in the second pass for the F1295 alloy but insufficient for the Inconel 718.
severe plastic deformation, high-pressure sliding, incremental feeding, Vickers microhardness, superplasticity, finite element method(FEM)
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