The Effect of Forging Conditions on Final Macrostructure of Slab Ingot from the 55NiCrMoV7 Tool Steel

The paper presents numerical modelling and an operational experiment to forge a slab ingot P40N from 55NiCrMoV7 tool steel and the procedure for the optimization of its production. The aim of the numerical simulation of forging was to verify the existing procedure of forging a plate from a conventional polygonal 8K forging ingot and a slab ingot with a polygonal shape of P40N surfaces. The effect of the shape of the ingot on the achievement of the required forging reduction and strain after the cross section of the forging of the plate, with final dimensions of approximately 1010 mm width × 310 mm thickness × 5350 mm length, was studied. The results obtained in the operational experiment showed satisfactory qualitative parameters of the steel forging from the slab P40N ingot which were in accordance with the predicted results of numerical simulations. The results indicated that in selected cases the use of a slab P40N ingot instead of the conventional polygonal 8K forging ingot can be considered in the production of certain plate-type forgings.

The origin of the word mazija ‘steel’

The word mazija ?steel; forging ingot; a kind of ordeal which required plucking red-hot iron from a cauldron of boiling water? is common in the western part of the Shtokavian dialect continuum. Its area includes the Zeta-Raska, the Eastern Herzegovinian and the Younger Ikavian dialect, the first of the Old Shtokavian and the other two of the Neo-Shtokavian type. There are no attestations of this word earlier than the first half of the 18th century. So far, it has been mainly believed to share a common origin with the homonymous mazija ?oak gall? from Turkish maz? id. This stance is hardly acceptable in view of the fact that not only the meanings of the two words but also their geographical distributions strongly diverge, mazija in the oak gall sense being limited to the Kosovo-Resava and Timok-Prizren dialect areas of southern Serbia. The comparison with French maz?e ?refined iron?, is even more doubtful, because this term has been attested only since 1824 and with no known etymology, The true origin of m?zija < maz?ja (gvozdja) should be sought in the late Greek (5th century AD) ????(?)? ??? ??????? ?iron mass shaped by a blacksmith?; the plural form ????? ??????? occurs in a Greek charter issued in 1347 by the Serbian tsar Dusan to the Great Lavra on Mt Athos. Curiously enough, in two Serbian founding charters of the same epoch there is a parallel passage where among other yearly incomes granted to the monastery iron ingots are mentioned, designated here by the gen. pl. nad'('), with complements gvozd(i)ja ?of iron? and m?r?nyh' ?of a standard weight?. The term is Slavic nada or nado, derivative from

Evaluation of the Chemical Composition and Microcleanliness of the Steel Samples from the Heavy Forging Ingot

The paper presents new results obtained from the evaluation of the chemical composition, microcleanliness and structure of the 90-ton heavy ingot cast in two successive heats, in which the content of Cu and Ni was intentionally modified in order to assess the degree of mutual mixing of the two heats in the ingot volume during the steel casting and solidification. For determination of chemical composition, spectral analysis and LECO were used. Microcleanliness evaluation was carried out on a Hitachi microanalytical complex equipped with the energy-dispersive spectrometer Vantage. To assess the composition of oxide non-metallic inclusions ternary diagrams were used. Structure of the basic steel matrix was induced by etching. The evaluation showed that in the casting of two successive heats, a certain degree of inhomogeneity of chemical composition, especially in the lower part of the ingot can be assumed in case of different composition. A greater segregation of sulphur in the central top part of the ingot was also detected. However, microcleanliness of the entire ingot is in general very good with low proportions of non-metallic inclusions.