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Title: Chemical banding revealed by chemical etching in a cold-rolled metastable stainless steel

The current work describes the metallographic characterization of the initial microstructure of a cold rolled precipitation hardening semi-austenitic stainless steel (12Cr–9Ni–4Mo–2Cu–1Ti, in wt.%). The use of the Lichtenegger and Blöch (L–B) color etching solution has been shown to reveal not only the phases present in the microstructure, but also the existence of chemical banding along the rolling direction. The L–B reagent has been found to color the microstructure in bands depending on what alloying elements have segregated to each band. Two-dimensional electron probe microanalysis (EPMA) maps have shown that Ni, Cu and Ti segregate together in the bands, while Cr has an opposite behavior. Mo has a mixed segregation behavior although much weaker than the other elements and more prompt to segregate like Ni does. A direct comparison of light optical micrographs with the EPMA maps of the same area of the microstructure has enable to establish a direct relationship between the alloying element band concentration and the resulting etching color contrast obtained with the L–B reagent. Thermodynamic calculations predict that solidification in this steel takes place with ferrite as the primary phase. Equilibrium partitioning coefficient calculations seem to support the observed segregation patterns. - Highlights: • A cold rolledmore » metastable stainless steel has been characterized thoroughly. • EPMA shows that Ni, Cu and Ti segregate together; Cr in an opposite way. • L–B color etching is sensitive to the segregation of these chemical elements. • This chemical banding has been reduced by applying a homogenization heat treatment. • Partitioning coefficient calculations agree with the observed segregation patterns.« less
Authors:
 [1] ;  [2] ;  [2] ;  [1]
  1. MATERALIA Research Group, Department of Physical Metallurgy, Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Av. Gregorio del Amo 8, 28040 Madrid (Spain)
  2. Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)
Publication Date:
OSTI Identifier:
22288670
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 84; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AUSTENITIC STEELS; COLOR; ELECTRON MICROPROBE ANALYSIS; ETCHING; FERRITE; MICROSTRUCTURE; PRECIPITATION HARDENING; SEGREGATION; STAINLESS STEELS