Paper Title:
Effect of Cooling Rate on Morphology and Crystallography of Lath Martensite in Fe-Ni Alloys
  Abstract

The development of blocks and subblocks in the lath martensite was observed with SEM/EBSD and TEM/Kikuchi diffraction patterns analyses. Morphology of lath martensite formed below Ms temperature was observed using step quenching method in 18 mass% Ni maraging steel. The development of lath martensite structure can be described as follow; lath groups with single K-S variant start to form at the austenite grain boundary. Next, other sub-blocks appear adjacent to the lath groups formed first and these lath groups form macroscopic blocks observed in optical microscopy. The morphologies of the lath martensite in Fe -23 mass% Ni alloy cooled at different cooling rates after austenitization were also observed. The packet size and block thickness decreases with increasing cooling rate, although the sub-block thickness do not change. A packet locally contains small packets with different relationship of close packed planes, and the amount of small packets increases with increasing the cooling rate.

  Info
Periodical
Materials Science Forum (Volumes 638-642)
Main Theme
Edited by
T. Chandra, N. Wanderka, W. Reimers , M. Ionescu
Pages
1459-1463
DOI
10.4028/www.scientific.net/MSF.638-642.1459
Citation
S. Morito, R. Igarashi, K. Kamiya, T. Ohba, T. Maki, "Effect of Cooling Rate on Morphology and Crystallography of Lath Martensite in Fe-Ni Alloys", Materials Science Forum, Vols. 638-642, pp. 1459-1463, 2010
Online since
January 2010
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