Naslov
A sudy of a specific casting defect in high-manganese steel castings

Autori
Unkić, Faruk ; Zoran, Kivač ; Živčić, Miroslav

Izvornik
Livarski vestnik (0024-5135) 45 (1998), 3/4; 107-113

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Casting defect; cold shut; high-manganese steel castings

Sažetak
A characteristic type of defect cold shut or cold lap, which occurs in relatively complicated castings track-blocks, was investigated. Austenitic high-manganese steel castings from industrial production were used. The specimens for microstructure examination were taken at a characteristic location of defects and prepared by the standard metallographic technique. Special attention was given to the detection of inclusion and cold laps. The quality analysis of the precipitated phases 'in situ' was carried out by a scanning electron microprobe analyser. The precipitated phases were determined by X-ray diffraction using a Philips diffractometer and CoK radiation. Metallographic analysis of the specimen shows the appearance of a curved discontinuity of a crack across the confluence weld, which is followed by a series of inclusions and porosity. Etching of microstructure at this location demonstrates decarburization of the surface, which is probably a result of oxidation during heat treatment, and is responsible for martensite presence in this area. A defect in the form of a cold shut is appeared as a result of collision of two melt streams at the place, which is most distant from the ingate of the moulding cavity. Microstructure analysis of a cross section of the sample at the place of cold shut shows the presence of complex manganese, silicon and aluminium oxides, which is caused by the sucking of the thin, fluid surface layer in the bulk melt during the collision of two streams. Inclusions, their origin and the process variables have a major influence on the defect formation.

Izvorni jezik
Engleski

Znanstvena područja
Metalurgija

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