Evaluations of the Elevated Temperature Tensilde and Creep-Rupture Properties of 12 to 27 Percent Chromium Steels

1980 ◽  
1988 ◽  
Vol 133 ◽  
Author(s):  
Akitsugu Fujita ◽  
Tatsuki Matsumoto ◽  
Makoto Nakamura ◽  
Yorimasa Takeda

ABSTRACTIntermetallic compound Ni3Al(γ′) is one of the major constituents in Ni-base superalloys. But it is not used by itself for structural use because of its low ductility and low strength.In the present study, the improvement of elevated temperature mechanical properties of Ni3Al intermetallic compound is pursued by addition of such elements as Fe, Ti, Cr, V, Nb, Ta, Mo, W, Zr and Hf. These results show that Ni 3AI which contains some elements substituting for Al has better mechanical properties and creep rupture properties than commercial Inconel 713C.


The effect of residuals and other deliberate minor additions on the elevated temperature properties of austenitic, CrMo and CrMoV steels is reviewed and those that affect these properties are identified. The elements boron, molybdenum, nitrogen and phosphorus in austenitic steels all increased creep rupture life although only boron and molybdenum were beneficial to rupture ductility. In the ferritic steels the embrittling elements antimony, arsenic, phosphorus and tin were considered together with aluminium, copper, silicon, titanium and boron. It is apparent that the effect of an individual element on creep rupture properties is dependent on the other elements present. However, in a 1 %CrMoVTiB steel additions of copper plus nickel and arsenic plus tin decrease rupture life although only the latter two reduce ductility. Similarly, in a 2 1/4% Cr1% Mo steel arsenic has a detrimental effect on ductility and tin and phosphorus have been identified as segregating to prior austenite grain boundaries. In contrast, silicon in a 2 1/4%Cr1 %Mo steel can improve ductility. Aluminium can improve both the creep life and ductility of 1 %CrMoVTiB steels, as can boron in the presence of titanium.


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