Precision Cast vs. Wrought Superalloys

Tien, J. K.; Borofka, J. C.; Casey, M. E.

doi:10.1007/bf03257587

Cited by 4 publications

(2 citation statements)

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“…It follows that grain refinement necessitates both ease of nucleation and inhibition of the continued growth of crystallites in the melts. The existing knowledge of grain size control can be divided in three basic ways [3,4]: mechanically, chemically or thermally. That is agitation of the melt during the freezing, nucleation promoting and growth hindering additions, or rapid cooling.…”

Section: Grain Refinement Methods and Their Application To Superalloysmentioning

confidence: 99%

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Cast Structure and Mechanical Properties of Fine Grained Superalloy K4169 by Addition of Refiners

Liu¹,

Huang²,

Xiong³

et al. 2004

Superalloys 2004 (Tenth International Symposium)

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Grain size and microstructural features of cast superalloy K4169 were investigated under various melting and casting conditions together with the addition of grain refiners. It is found that lowering the pouring temperature and adding refiners to the melt before pouring can lead to grain refinement of matrix and improve the proportion of equiaxed grains. At a conventional pouring temperature of 1400 , the average size of equiaxed grains could be refined to the order of ASTM 3.2 (0.17 mm), the proportion of equiaxed grains at the transverse cross-section could be improved from 56% to 99% with addition of a trace intermetallic compound into the melt. The results also indicate that the length of primary dendrite is shortened with the addition of refiners, but the secondary dendrite arm spacing keeps almost unchanged. Meanwhile, the microsegregation of main elements such as Fe, Cr, Nb, Mo and Ti is alleviated with the decrease in grain size, and the grains have transformed from dendrite to granulation in fine-grained castings. The amount of microporosity in samples with the addition of refiners can be greatly reduced. The mechanisms of grain refinement and increase in equiaxed grain proportion were proposed.Tensile properties at room temperature and at 700 were tested. The rupture strength, yield strength, elongation and reduction of area for refined grains are all more superior to those of coarse ones. Whereas the elongation and reduction of area of fine grained samples decrease at 700 . Low cycle fatigue (LCF) properties of refined grain samples at room temperature are improved significantly. In addition, the degree of dispersion of LCF data of fined grain samples is diminished.

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Section: Grain Refinement Methods and Their Application To Superalloysmentioning

confidence: 99%

“…Since 1970's, developments were made for replacing to forged turbine wheels which have been plagued with large grains in the central hub areas, a location that is seldom adequately worked [3]. Alternatively, the optimum grain configuration can be obtained with investment casting.…”

Section: Introductionmentioning

confidence: 99%