Use of a boron addition to prevent intergranular embrittlement in Fe-12Mn

Journal Article · Tue Jul 01 04:00:00 EDT 1980 · Metall. Trans., A; (United States)

DOI:https://doi.org/10.1007/BF02668143· OSTI ID:5893719

Hwang, S K ^[1]; Morris, Jr, J W

---

1. Brookhaven National Lab., Upton, NY

Fe-12Mn alloys undergo failure by catastrophic intergranular fracture when tested at low temperature in the as-austenitized condition, a consideration which prevents their use for structural applications at cryogenic temperatures. The present research was undertaken to identify modifications in alloy composition or heat treatment which would suppress this embrittlement. Chemical and microstructural analyses were made on the prior austenite grain boundaries within the alloy in its embrittled state. These studies failed to reveal a chemical or microstructural source for the brittleness, suggesting that intergranular brittleness is inherent to the alloy in the as-austenitized condition. The addition of 0.002 to 0.01 wt % boron successfully prevented intergranular fracture, leading to a spectacular improvement in the low temperature impact toughness of the alloy. Autoradiographic studies suggest that boron segregates to the austenite grain boundaries during annealing at temperatures near 1000/sup 0/C. The cryogenic toughness of a Fe-12Mn-0.002B alloy could be further improved by suitable tempering treatments. However, the alloy embrittled if inappropriate tempering temperatures were used. This temper embrittlement was concomitant with the dissolution of boron from the prior austenite grain boundaries, which reestablishes the intergranular fracture mode. 14 figures.

• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5893719
• Journal Information: Metall. Trans., A; (United States), Journal Name: Metall. Trans., A; (United States) Vol. 11; ISSN MTTAB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
ANNEALING
AUTORADIOGRAPHY
BORON ADDITIONS
BORON ALLOYS
CRYSTAL STRUCTURE
DUCTILITY
EMBRITTLEMENT
FRACTURE PROPERTIES
GRAIN BOUNDARIES
HEAT TREATMENTS
IMPACT STRENGTH
IRON ALLOYS
IRON BASE ALLOYS
MANGANESE ALLOYS
MECHANICAL PROPERTIES
MICROSTRUCTURE
SEGREGATION
TEMPERING
TENSILE PROPERTIES