Influence of Severe Thermomechanical Treatment on Formation of Nanocrystalline Structure in Ni 718 and Ni 718Plus Alloys and their Mechanical Properties

Abstract:

Article Preview

The influence of severe thermomechanical treatment via multiple forging on the formation of a nanocrystalline (NC) structure in bulk samples of Alloy 718 and ATI 718Plus has been investigated. It was observed that a step-wise decrease of processing temperature from 950 down to 575°C allowed the refinement of the initial coarse grain structure to a NC state. Investigations of structural changes in the deformed samples have shown that extending the temperature interval of dynamic recrystallization to low homologous temperatures resulted in the formation of a fine-grained recrystallized structure. The temperature of NC structure formation in ATI Alloy 718Plus was 50-100°С higher than that required for alloy 718. This was due to the presence of the additional γ′-phase, which increased the recrystallization temperature. This decreased the total strain required to produce NC structure, as compared with Alloy 718. It was observed that increasing the total strain and decreasing temperatures step-wise during deformation via multiple forging resulted in a uniform structure across the cross-section of the samples. The room temperature mechanical properties of the investigated alloys with various grain sizes are also compared.

Info:

Periodical:

Materials Science Forum (Volumes 584-586)

Edited by:

Yuri Estrin and Hans Jürgen Maier

Pages:

458-463

DOI:

10.4028/www.scientific.net/MSF.584-586.458

Citation:

S. K. Mukhtarov et al., "Influence of Severe Thermomechanical Treatment on Formation of Nanocrystalline Structure in Ni 718 and Ni 718Plus Alloys and their Mechanical Properties", Materials Science Forum, Vols. 584-586, pp. 458-463, 2008

Online since:

June 2008

Export:

Price:

$35.00

In order to see related information, you need to Login.

In order to see related information, you need to Login.