The effect of manganese on the onset of the stage 2 reaction in an austempered ductile iron matrix

Technical Report · Thu Feb 01 04:00:00 EST 1990

DOI:https://doi.org/10.2172/6788389· OSTI ID:6788389

Hagen, K. N.

Austempered ductile irons (ADIs) possess a unique combination of toughness and ductility plus high strength which make them attractive alternatives to other metal castings. ADIs can have tensile strengths up to 230 ksi with a 1% elongation and high hardness for wear resistant applications, or tensile strengths of approximately 150 ksi and elongations of 14% where a large amount of ductility is required. Austempering is a two step process: complete transformation to the austenite ({gamma}) phase; and a quench and hold in the temperature range of 270--420{degree}C for some time followed by cooling to room temperature. This quench must be sufficiently rapid to avoid formation of pearlite or ferrite if the best mechanical properties are to be obtained. This thesis presents the results of a number of experiments aimed at determining the effect of Mn on the length of the Stage 1 reaction. (austenite decomposes into bainitie ferrite and high carbon austenite). A basic knowledge of the effects of Mn will yield a more complete understanding of the austempering process for the normal case and also when microsegregation is present. The onset time for Stage 2 (high carbon austenite decomposes into bainitic ferrite plus carbides) in ductile irons is a critical parameter because of the associated degradation of the mechanical properties which result from carbide formation.

• Research Organization: Ames Lab., IA (USA)
• Sponsoring Organization: DOE/ER
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6788389
• Report Number(s): IS-T-1476; ON: DE90011804
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101 -- Metals & Alloys-- Preparation & Fabrication
360102 -- Metals & Alloys-- Structure & Phase Studies
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
AUSTENITE
CARBON ADDITIONS
CHEMICAL ANALYSIS
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIFFRACTION
DUCTILITY
ELEMENTS
HARDNESS
IRON ALLOYS
IRON BASE ALLOYS
MANGANESE
MANGANESE ALLOYS
MECHANICAL PROPERTIES
METALLURGICAL EFFECTS
METALS
MICROSTRUCTURE
PHASE TRANSFORMATIONS
SCATTERING
TENSILE PROPERTIES
TRANSITION ELEMENTS
X-RAY DIFFRACTION