SYMPOSIA PAPER Published: 01 January 1990

Precipitation Sensitivity to Alloy Composition in Fe-Cr-Mn Austenitic Steels Developed for Reduced Activation for Fusion Application


Special austenitic steels are being designed in which alloying elements like molybdenum, niobium, and nickel are replaced with manganese, tungsten, vanadium, titanium, and/or tantalum to reduce the long-term radioactivity induced by fusion reactor irradiation. However, the new steels still need to have properties otherwise similar to commercial steels like Type 316. Precipitation strongly affects strength and radiation-resistance in austenitic steels during irradiation at 400 to 600°C, and precipitation is also usually quite sensitive to alloy composition. The initial stage of development was to define a base Fe-Cr-Mn-C composition that formed stable austenite after annealing and cold-working, and resisted recovery or excessive formation of coarse carbide and intermetallic phases during elevated temperature annealing. These studies produced a Fe-12Cr-20Mn-0.25C base alloy. The next stage was to add the minor alloying elements titanium, vanadium, phosphorous, and boron for more strength and radiation-resistance. One of the goals was to produce fine MC precipitation behavior similar to the Ti-modified Fe-Cr-Ni prime candidate alloy (PCA). Additions of Ti + V + P + B produced fine MC precipitation along network dislocations and recovery/re-crystallization resistance in 20% cold-worked material aged at 800° for 168 h, whereas tungsten, titanium, W + Ti, or Ti + P + B additions did not. Addition of W +Ti + V + P + B also produced fine MC, but caused some σ phase formation and more recrystallization as well. These new alloys, therefore, achieved several of the initial design goals. Their fine MC precipitation and recovery/recrystallization behavior during aging is similar to that of the PCA. Calculations show that the new steels have over 103 times less long-term radioactivity than Type 316.

Author Information

Maziasz, PJ
Oak Ridge National Laboratory, Oak Ridge, TN
Klueh, RL
Oak Ridge National Laboratory, Oak Ridge, TN
Price: $25.00
Contact Sales
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Developed by Committee: E10
Pages: 56–79
DOI: 10.1520/STP24949S
ISBN-EB: 978-0-8031-5113-0
ISBN-13: 978-0-8031-1267-4