Effect of phosphorus on the microstructure and stress rupture properties in an Fe-Ni-Cr base superalloy

This article describes the effect of phosphorus on the microstructure and stress rupture property at 650 °C in an Fe-Ni-Cr base superalloy. The results showed that phosphorus markedly improved the intergranular precipitation in the range of 0.0005 to 0.016 wt pct, which facilitated M23C6 and M3B2 pr...

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Bibliographic Details
Published in:Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 1997-03, Vol.28 (3), p.649-654
Main Authors: SUN, W. R, GUO, S. R, LU, D. Z, HU, Z. Q
Format: Article
Language:English
Subjects:
Alloys
Applied sciences
Chromium
Cross-disciplinary physics: materials science
rheology
Elongation
Exact sciences and technology
Fatigue, corrosion fatigue, embrittlement, cracking, fracture and failure
Fatigue, embrittlement, and fracture
Grain boundaries
Intergranular precipitation
Iron
Materials science
Metals. Metallurgy
Microstructure
Nickel base alloys
Phosphorus
Physics
Rupture
Superalloys
Temperature
Treatment of materials and its effects on microstructure and properties
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Summary:This article describes the effect of phosphorus on the microstructure and stress rupture property at 650 °C in an Fe-Ni-Cr base superalloy. The results showed that phosphorus markedly improved the intergranular precipitation in the range of 0.0005 to 0.016 wt pct, which facilitated M23C6 and M3B2 precipitation but inhibited the formation of MC carbide. A too high phosphorus addition (0.051 wt pct P) resulted in an excessive precipitation at grain boundaries, while a too low phosphorus content (0.0005 wt pct P) led to many precipitate-free grain boundaries. Phosphorus also enlarged the size of the γ′ particles and lowered its stability, that η-Ni3Ti preferred to form in the alloy with 0.051 wt pct P. Due to the improvement of the microstructure, appropriate amount of P content significantly prolonged the rupture life of the alloys in the range of 0.0005 to 0.016 wt pct. The peak value was 660 hours at 0.016 wt pct, more than 4 times that of the alloy with 0.0005 wt pct phosphorus, but phosphorus reduced the fracture elongation. The mechanism by which phosphorus influenced the alloy is discussed.
ISSN:1073-5623
1543-1940
DOI:10.1007/s11661-997-0050-5