Comparison of Discontinuous Yielding Phenomenon and Adiabatic Temperature Rising of Ti-5553 Alloy Prepared by Powder and Ingot Metallurgy Approaches during Hot Compression

Abstract:

Discontinuous yielding phenomenon (DYP) and adiabatic temperature rising (ATR) effect have been investigated in this paper for Ti-5553 (Ti-5Al-5Mo-5V-3Cr) alloys manufactured by powder metallurgy (PM) and ingot metallurgy (IM) approaches based on hot compression testing conducted at the temperature range of 700 °C to 1100 °C and the strain rate range of 0.001 s_^-1 to 10 s_^-1. The results show that the magnitude of yield drop exhibits a positive correlation to strain rate but nearly a negative correlation to deformation temperature for both PM and IM alloys, and the occurrences of DYP in the alloys are elucidated by the dynamic theory. IM alloy shows a higher degree of yield drop than PM alloy at the same condition because of low initial dislocation density at as-cast state and the subsequently promoted newly-generated mobile dislocation from grain boundary. Strong positive correlation between ATR effect and strain rate but intensive negative correlation when it subjected to deformation temperature are uncovered for the two alloys. PM alloy shows a lower degree of ATR effect at the same processing condition than IM alloy as a result of its lower deformation resistance and higher deformation compatibility.

Key words:Ti-5553 alloy; powder metallurgy; hot deformation; discontinuous yielding phenomenon; adiabatic temperature rising