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Title: Design and optimization of stepped austempered ductile iron using characterization techniques

Conventional characterization techniques such as dilatometry, X-ray diffraction and metallography were used to select and optimize temperatures and times for conventional and stepped austempering. Austenitization and conventional austempering time was selected when the dilatometry graphs showed a constant expansion value. A special heat color-etching technique was applied to distinguish between the untransformed austenite and high carbon stabilized austenite which had formed during the treatments. Finally, it was found that carbide precipitation was absent during the stepped austempering in contrast to conventional austempering, on which carbide evidence was found. - Highlights: • Dilatometry helped to establish austenitization and austempering parameters. • Untransformed austenite was present even for longer processing times. • Ausferrite formed during stepped austempering caused important reinforcement effect. • Carbide precipitation was absent during stepped treatment.
Authors:
 [1] ; ; ;  [2]
  1. Centro de Investigación en Materiales Avanzados-Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, Z.C. 31109, Chihuahua (Mexico)
  2. Facultad de Ingeniería, Universidad Autónoma de San Luis Potosí, Sierra Leona 550, Lomas 2a. sección, Z.C. 78210, San Luis Potosí (Mexico)
Publication Date:
OSTI Identifier:
22285081
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 83; 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; AUSTENITE; CARBON; COLOR; DILATOMETRY; ETCHING; HEAT TREATMENTS; IRON; METALLOGRAPHY; OPTIMIZATION; PHASE TRANSFORMATIONS; X-RAY DIFFRACTION