W publikacji przedstawiono charakterystykę staliwa stopowego wysokomanganowego, potocznie określanego mianem staliwa Hadfielda. Staliwa z tej grupy w warunkach wzrostu ciśnienia lub obciążenia, np. w wyniku uderzenia, wykazują dużą skłonność do tzw. umocnienia zgniotem, objawiającego się zwiększeniem powierzchniowej twardości i odporności na zużycie przy zachowaniu ciągliwości rdzenia.
EN
The paper presents the characteristics of a high-manganese alloy cast steel, commonly referred to as Hadfield cast steel. Cast steels of this group demonstrate a high tendency to the so-called strain hardening under the conditions of pressure or load increase, e.g. as a result of an impact, which is manifested by an increase in surface hardness and wear resistance while maintaining the ductility of the core. This is decisive for the applicability of a high-manganese cast steel for the castings of hammers and liners for coal mills and other mills, crusher cones, working elements of construction machines as well as cast elements of turnouts. In particular, the paper presents the chemical composition and usable properties of a high- -manganese cast steel intended for use in railway infrastructure as well as the characteristics of its microstructure finally shaped by heat treatment.
The paper presents the results of research conducted in the field of crystallization and microstructure of duplex alloy cast steel GX2CrNiMoCuN 25-6-3-3 grade. The material for research was the above-mentioned cast steel with a chemical composition compliant with the relevant PN-EN 10283 standard, but melted at the lowest standard allowable concentration of alloying additives (some in short supply and expensive), i.e. Cr, Ni, Mn, Mo, Cu and N. The analysis of the crystallization process was performed based on the DTA (Derivative Thermal Analysis) method for a stepped casting with a thickness of individual steps of 10, 20, 40 and 60 mm. The influence of wall thickness was also taken into account in the cast steel microstructure testing, both in the as-cast state and after solution heat treatment. The phase composition of the cast steel microstructure was determined by using an optical microscope and X-ray phase analysis. The analysis of test results shows that the crystallization of tested cast steel uses the ferritic mechanism, while austenite is formed as a result of solid state transformation. The cast steel under analysis in the as-cast state tends to precipitate the undesirable σ-type Fe-Cr intermetallic phase in the microstructure, regardless of its wall thickness. However, the casting wall thickness in the as-cast state affects the austenite grain size, i.e. the thicker the casting wall, the wider the γ phase grains. The above-mentioned defects of the tested duplex alloy cast steel microstructure can be effectively eliminated by subjecting it to heat treatment of type hyperquenching.
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