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It has been demonstrated that it is impossible to use copper sulphide alone as grain-growth inhibitor in GO steel owing to the difficulty of producing the necessary volume fraction of particles without precipitation of iron sulphide at the same time. For the purpose of the inhibition produced, the contribution of copper as an element participating in the composition of the mixed precipitates Mn(x)Cu(y)S(x+y), is also efficacious. Better magnetic behaviour (B(800) = 1.86T, P(1.7) = 1.13 w/kg and th = 0.28 mm) has been encountered for a product of mixed composition Cu = 1100 ppm, Mn = 630 ppm and S = 260 ppm, in the context of the cases analysed. A further indication that has emerged is the greater stability of the magnetic characteristics vis-à-vis fluctuations of the sulphur and carbon content, in the case of alloys with a copper content between 1000 and 2000 ppm. A useful process has also been developed for the extraction of sulphide particles from the ferritic matrix and for subsequent determination of the Mn, Cu and sulphur by chemical methods. Lastly, no alternative final annealing treatment has been recognised for the GO product that leads to better magnetic results than those obtained using the standard process starting from alloys with a mixed copper/manganese composition.

Additional information

Authors: CENTRO SVILUPPO MATERIALI SPA, Centro Sviluppo Materiali SpA, Roma (IT)
Bibliographic Reference: EUR 13637 IT (1991) 101 pp., FS, ECU 10
Availability: (2)
ISBN: ISBN 92-826-2828-0
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