Intragranular nucleation of austenite

Atamert, Serdar and King, Julia E. (1991). Intragranular nucleation of austenite. Zeitschrift für Metallkunde, 82 (3), pp. 230-239.

Abstract

The mechanism of intragranular nucleation of austenite in a duplex stainless steel (Fe-23.1 Cr-6.1 Ni-3.1 Mo-O.165 N-0.017 C, wt.%) weld metal and heat-affected zone (HAZ) has been examined. In the weld metal the acicular austenite is found to nucleate intragranularly on inclusions and subsequent plates form sympathetically resulting in a fine interlocked microstructure. Austenite plates adopt the Kurdjumov-Sachs orientation relationship with the ferrite matrix and grow with diffusion-controlled mechanism as evident from partitioning of substitutional alloying elements. At least one set of fine intrinsic dislocations on the austenite/ferrite interphase interfaces is observed suggesting that the boundaries are semi-coherent. The high cooling rates involved in the HAZ result in a supersaturated ferrite matrix where precipitation of intragranular austenite occurs as a result of reheating associated with subsequent passes. Austenite particles in the HAZ nucleate preferentially away from gain boundary austenite allotriomorphs indicating that intragranular precipitation is favoured by the supersaturated matrix.

Divisions: Aston University (General)
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Uncontrolled Keywords: precipitation metallography,stainless steel,welds,aurami equation,austenite ferrite interphase interfaces,austenite nucleation,duplex stainless steels,intragranular nucleation,Kurdjumov Sachs orientation,iron and steel metallography,heat affected zone,Metals and Alloys
Published Date: 1991-03

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