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Structural superplasticity of a fine‐grained and rapidly solidified ultra‐high carbon‐alloy tool steel X 245 VCr 10 5
Author(s) -
Frommeyer Georg,
Speis HansJosef
Publication year - 1991
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.199101288
Subject(s) - superplasticity , materials science , metallurgy , carbide , grain boundary sliding , alloy , ultimate tensile strength , strain rate , grain boundary , microstructure
The fine‐grained ultra‐high carbon‐alloy tool steel X 245 VCr 10 5, containing large volume fractions of special vanadium and chromium carbides within a ferritic solid solution matrix has been produced by rapid solidification – meltatomization – and powder metallurgical techniques. This steel exhibits structural superplasticity in the temperature regime from 900 to 1150°C at initial strain rates of about ∊̇ = 10 −3 s −1 . High strain‐rate sensitivity parameters of m > 0.4 and uniform tensile elongations up to 950% were recorded. The dominant deformation mechanism in the superplastic region is grain‐boundary sliding accommodated by lattice diffusion. The failure of superplastically strained samples is caused by interlinkages of cavities at matrix/carbide interfaces.