Steel initiative: Development of superplastic steel processing

Technical Report · Fri Sep 01 00:00:00 EDT 1989

DOI:https://doi.org/10.2172/5377591· OSTI ID:5377591

Sherman, D. H.; Leach, J. M.; Hayes, A. F.; Lemsky, J. A.; Thomas, J. D.; Geiger, G. H.; Goldberg, A.; Strum, M. J.; Sherby, O. D. ^[1]

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1. Caterpillar, Inc., Peoria, IL (USA)

The influence of aluminum content and thermomechanical processing steps on developing fine microstructures in ultrahigh carbon steels (UHCS) was examined. The presence of aluminum results in ultrafine pearlitic structures without proeutectoid carbide networks, and greatly retards the eutectoid transformation kinetics. This retardation facilitates processing, which involves various combinations of DET and DETWAD steps. By applying the transformation kinetics as a guide, uniform through-thickness microstructures and superplastic properties are readily obtainable in thick sections. Superplasticity studies revealed that superplastic behavior is enhanced by aluminum additions and by increasing the amount of warm deformation during DETWAD processing. This trend is attributed to a decrease in ferrite grain size and an increase in the ferrite-grain-boundary angle, and hence, to an increase in the ease of grain-boundary sliding. Studies on the cold-rolling characteristics of a UHCS-Al alloy reveal that it can be cold-rolled to 50% in the fully pearlitic condition without annealing, and to over 60% in the fully spheroidized condition. Room-temperature tensile properties were obtained on DETWAD-processed material. Identical properties were obtained in the rolling and transverse directions, which is attributed to the ultrafine, isotropic microstructure. Two trial strand-casting runs were initiated. Modified Fe-C diagrams incorporating aluminum and/or silicon additions were constructed. Materials have been processed both at LLNL and at Ladish for evaluation of their die-filling capability.

• Research Organization: USDOE Assistant Secretary for Conservation and Renewable Energy, Washington, DC (USA). Office of Industrial Programs
• Sponsoring Organization: DOE/CE
• OSTI ID: 5377591
• Report Number(s): DOE/CE-0256-1; ON: DE90003277
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM
METALLURGICAL EFFECTS
CARBON STEELS
PLASTICITY
AUSTENITE
DECARBONIZATION
GRAIN BOUNDARIES
GRAIN SIZE
MECHANICAL PROPERTIES
MICROSTRUCTURE
PHASE DIAGRAMS
PROGRESS REPORT
THERMOMECHANICAL TREATMENTS
ALLOYS
CARBON ADDITIONS
CRYSTAL STRUCTURE
DIAGRAMS
DOCUMENT TYPES
ELEMENTS
FABRICATION
HEAT TREATMENTS
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS WORKING
METALS
SIZE
STEELS
360101* - Metals & Alloys- Preparation & Fabrication
360103 - Metals & Alloys- Mechanical Properties
360102 - Metals & Alloys- Structure & Phase Studies