Authors' reply
- PDF / 114,883 Bytes
- 1 Pages / 613 x 788.28 pts Page_size
- 61 Downloads / 211 Views
In summary, we see no real disagreement between our two studies. McCartney has proven quite clearly in his experiments that the ability of an AI-Ti master alloy to grain refine is sensitive to the processing used in its manufacture and, consequently, to the structure of the aluminide in the master alloy. Unfortunately, we chose an awkward location in our paper to reflect on the commercial use of grain refiners (which contain boron), and McCartney quite naturally assumed that we were referring to AI-Ti alloys. We are sorry for the confusion. In fact, commercial AI-Ti grain refiners (which do not contain boron) are usually produced by casting from high temperature to give the flake-type structure. A blocky A1-Ti product is rarely used commercially.
REFERENCES REFERENCES 1. M. M. Guzowski, G. K. Sigworth, and D. A. Sentner: Metall. Trans. A, 1987, vol. 18A, pp. 603-19. 2. D. Hadlet, D.G. McCartney, and S.R. Thistlethwaite: in Aluminum Technology '86, Institute of Metals Book No. 391, London, 1986, pp. 125-32. 3. L. Arnberg, L. B~ickerud, and H. Klang: Metals Tech., 1982, vol. 9, pp. 1-6. 4. G. R Jones and J. Person: Metall. Trans. B, 1976, vol. 7B, pp. 223-34.
Authors' Reply M.M. GUZOWSKI, G. K. SIGWORTH, and D. A. SENTNER We welcome the experiments of McCartney. We published the results of our experiments on AI-Ti-B grain refiners hoping to stimulate further research by others. In other words, our views were offered as hypotheses and general observations which required further experimental verification. McCartney has taken issue with our claim that a blocky refiner is fast acting, whereas a flake-type structure (cast from high temperature) is slow acting. (The problem arises from the first paragraph on page 604 of our paper.) We were referring here to the c o m m e r c i a l use of grain refiners, nearly all of which contain boron. When boron is present, the high temperature product is definitely slow acting, whereas the low temperature (blocky) material is fast acting. This is an observation based on tests of thousands of commercial heats. It is not an inviolable law, merely an observation which is true about 95 pct of the time. As far as A1-Ti alloys are concerned (which do not contain boron), McCartney's results are in disagreement with the earlier laboratory results of Biickerud and Klang 1'2 and Maxwell and Hellawell. 3'4 We will not try to explain this discrepancy, since no detail is given about the processing procedures used to produce McCartney's alloys. The addition level used by McCartney to test their A1-Ti master alloys was quite high: 0.05 pct Ti. A lower addition level would accentuate differences among the refiners, especially with respect to fade time and ability to act quickly.
METALLURGICAL TRANSACTIONS A
1. L. Arnberg, L. B~ickerud, and H. Klang: vol. 9, pp. 1-6. 2. L. Arnberg, L. B~ickerud, and H. Klang: vol. 9, pp. 7-13. 3. I. Maxwell and A. Hellawell: Acta Metall., 4.1. Maxwell and A. Hellawell: Acta Metall.,
Metals Technology, 1982, Metals Technology, 1982, 1975, vol. 23, pp. 895-99. 1975,
Data Loading...
