Accession Number : ADA462032


Title :   Alpha/Beta Heat Treatment of a Titanium Alloy with a Non-Uniform Microstructure (Preprint)


Descriptive Note : Journal article


Corporate Author : AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE


Personal Author(s) : Semiatin, S. L. ; Lehner, T. M. ; Miller, J. D. ; Doherty, R. D. ; Furrer, D. U.


Full Text : http://www.dtic.mil/get-tr-doc/pdf?AD=ADA462032


Report Date : AUG 2006


Pagination or Media Count : 42


Abstract : The effect of alpha/beta solution temperature and cooling rate on the evolution of microstructure during the heat treatment of Ti-6Al-2Sn-4Zr-2Mo-0.1Si (Ti6242Si) with a partially-spheroidized starting microstructure of equiaxed + remnant lamellar alpha was established. Experiments comprising induction heating to a peak temperature of 971 or 982 degrees C followed by cooling at a rate of 11 or 42 degrees C/min revealed that the volume fraction of the equiaxed alpha grew much more rapidly than the lamellar constituent. These results were explained semi-quantitatively using simple diffusion analyses of the growth of either spherical or elliptical particles, taking into account the soft-impingement of the concentration fields. Despite the much lower diffusivity of molybdenum, which appears to control the growth of primary alpha in Ti6242Si, the similarity of the overall kinetics compared to those measured previously for Ti-6Al-4V was explained on the basis of the higher supersaturations developed during cooldown in the present alloy.


Descriptors :   *MICROSTRUCTURE , *TITANIUM ALLOYS , *SOLUTION HEAT TREATMENT , COOLING , NONUNIFORM , IMPINGEMENT , DIFFUSIVITY , SUPERSATURATION


Subject Categories : METALLURGY AND METALLOGRAPHY
      PROPERTIES OF METALS AND ALLOYS
      FABRICATION METALLURGY


Distribution Statement : APPROVED FOR PUBLIC RELEASE