Investigation of transformation strengthening in precipitation-hardened Fe--Ni austenite

Journal Article · Wed Nov 01 04:00:00 EST 1978 · Metall. Trans., A; (United States)

DOI:https://doi.org/10.1007/BF02661945· OSTI ID:6344801

Jin, S ^[1]; Morris, Jr, J W; Chen, Y L; Thomas, G; Jaffee, R I

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1. Bell Labs., Murray Hill, NJ

Ausaged Fe--33Ni--3Ti and Fe--34Ni--3Ti--0.5Al austenitic alloys were transformation strengthened through sequential martensite (..cap alpha..' ..-->.. ..gamma..) and reverse martensitic transformations. An increase in yield strength of 20 to 30 ksi (130 to 210 MPa) was obtained, leading to alloy yield strengths near 180 ksi (1250 MPa) in the ausaged and transformation strengthened condition. The presence of the ..gamma..' precipitates formed on ausaging did not radically change the nature of the shear transformation nor the morphology and substructure of the transformation product. The presence of the ..gamma..' precipitates did, however, have the beneficial consequence that the ..cap alpha..' ..-->.. ..gamma.. reversion could be accomplished with slow heating rates without loss of transformation strengthening. The yield strength actually increased when a slow heating rate was used, a result attributed to the successful pinning of transformation induced defects by the ..gamma..' precipitates and to the occurrence of additional precipitation during heating. The efficient pinning of transformation induced defects had the further consequence that the alloys could be annealed for long periods after reversion to austenite without significant loss of strength.

• OSTI ID: 6344801
• Journal Information: Metall. Trans., A; (United States), Journal Name: Metall. Trans., A; (United States) Vol. 9:11; ISSN MTTAB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
ALUMINIUM ALLOYS
AUSTENITE
CARBON ADDITIONS
CRYSTAL STRUCTURE
HARDENING
IRON ALLOYS
IRON BASE ALLOYS
MARTENSITE
MECHANICAL PROPERTIES
MICROSTRUCTURE
NICKEL ALLOYS
PHASE TRANSFORMATIONS
PRECIPITATION HARDENING
TENSILE PROPERTIES
TITANIUM ALLOYS
YIELD STRENGTH