Effect of deformation heating on microstructure evolution during hot forging of Ti-6Al-4V

Kulakov, Mykola and Rahimi, Salah and Semiatin, S. Lee (2022) Effect of deformation heating on microstructure evolution during hot forging of Ti-6Al-4V. Metallurgical and Materials Transactions A, 53 (2). pp. 407-419. ISSN 1073-5623 (https://doi.org/10.1007/s11661-021-06493-1)

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Abstract

The effect of deformation heating on microstructure evolution during hot forging of Ti-6Al-4V was established. For this purpose, right-circular cylinders of Ti-6Al-4V with an equiaxed-α preform microstructure were preheated to a temperature between 1148 K (875 °C) and 1223 K (950 °C), and compressed to a 60-pct. height reduction in a screw press, yielding average true strain rates of ~ 5 to 20 s−1. Thermocouple measurements and corroborating finite-element-method (FEM) simulations quantified substantial deformation-heating-induced temperature increases. For all preheat temperatures, the heating transient led to an exposure above the equilibrium β transus temperature. Despite such temperature excursions, the volume fraction of equiaxed primary α in each forged billet was only slightly lower than that in the corresponding preheated condition. The source of such observations was rationalized on the basis of the (hypothesized) solute-concentration fields that develop during the heating and cooling transients experienced in high-rate deformation processing.

ORCID iDs

Kulakov, Mykola, Rahimi, Salah ORCID logoORCID: https://orcid.org/0000-0001-6461-988X and Semiatin, S. Lee;
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