Marvelės kapinyno geležies dirbinių metalografiniai, mechaninių savybių ir elementinės sudėties tyrimai

LTStraipsnyje pateikiami Marvelės kapinyno geležies dirbinių metalografinių, mechaninių savybių ir elementinės sudėties tyrimų rezultatai. Tyrimams naudoti 2006 metais ištirtų III-V a. griautinių kapų radiniai: kirviai (3), ietigaliai (4), peiliai (2) ir sagtis bei metalurginiai šlakai, gargažės ir geležies konkrecijos iš kapų aplinkos. Tyrimams taikyta įprasta metodika, tad jų rezultatai gali būti lyginami su kitų vietų duomenimis. Metalografinių tyrimų metu nustatyta, kad gaminant buvo gaunamos skirtingo kietumo dirbinio dalys. Kirviai gaminti iš dviejų atskirų geležies ruošinių, ietigaliai ir peiliai - iš vientisų. Elementinė dirbinių sudėtis yra panaši į kitų Lietuvos archeologinių vietų, tačiau egzistavo ir kai kurie skirtumai, kurie perša mintį apie nevietinę tokių dirbinių kilmę. [Iš leidinio]Reikšminiai žodžiai: Marvelės dirbiniai; Kalviškoji geležis; Mikrostruktūra; Elementinė sudėtis; Marvelė artefacts; Bloomery iron; Microstructure; Elemental composition.

ENThe region of Central Lithuania is known for a group of archaeological sites concentrated close to the river Nemunas. One of these, Marvele (in Kaunas), is the largest archaeologically investigated Lithuanian prehistoric burial ground. This cemetery has been investigated since 1991 and contains burials dating to the 2nd-12th centuries. It has provided an abundance of different types of burials and grave goods and also suggests some plausible interpretations for social events. The paper analyses material from the archaeological investigations in 2006 and presents the results of a metallographic, mechanical properties and chemical analysis of iron artefacts, metallurgical slag, iron droplets and clinker excavated in the Marvele cemetery. The elemental composition of iron droplets from Marvele (found in smelting slag) shows theirs similarity to that of droplets from other Lithuanian archaeological sites. However some small differences may be indicated, e.g., droplets from Marvele contain more cobalt (c. 0.164%, others contain av. 0.092% Co), but less phosphorus (c. 0.078%, when others - av. 0.432% P). The composition of the examined slag is similar to other Lithuanian archaeological slag, although the manganese oxide level is rather high (up to 10%) in the Marvele slag. The manufacturing technologies were studied using a number of socket axes (3 examples of one type), spearheads (4 examples of various types), knifes (2 examples of different types) and buckle, all from 3rd-5th-century inhumations. Metallographic analysis samples were taken from different parts of the iron artefacts: the cutting edges and longitudinal sections of the axes (3 examples) and spearheads (4 examples). This technique only allows one to presume what the forging sequence and the peculiarities of the metal were in the different parts of the artefacts.The material's hardness (Rockwell and microhardness) was determined for all the axes, spearheads, and knifes. The axes were forged from two separate pieces of iron. The core and cutting edge were made of a higher carburised material (up to 0.8% C), which was covered by a layer of a less carburized material, from which the socket was also forged. The material is steel with a ferrite and pearlite structure and a heterogeneous carbon content (HB 183-318, 187-363, 192-341, the highest HB being found on the cutting edge). The cutting edges were tempered. Meanwhile the spearheads and knifes were forged from a single piece of iron. The hardnesses that were determined are associated with different metal structures and different production technologies. Through the metallographic and elemental analysis, it was determined that the metal was produced in Marvelėj. The iron ore mining process and the production of iron tools were ascertained to have existed in the immediate vicinity during the 3rd-5th centuries. The iron weapons and tools suggest that the majority of all of the examined artefacts are of local production with the exception of two spearheads that were possibly imported (burials 1414,1468). The highly trained craftsmen who worked at this location were very proficient smiths and managed to produce the tools and weapons of high quality. [From the publication]