Izudin Dugić, Linnaeus University, Faculty of Technology, Department of Mechanical Engineering, Växjö, Sweden

EFFECT OF COOLING RATE ON THE CASTING DEFECTS OF HIGH CHROMIUM WHITE CAST IRON FOR THE IMPELLERS

Črtomir Mikyška¹, Gordana Gojsević Marić², ¹Livar d.d., Ivančna Gorica, Slovenia, ²Elkem AS , Sisak, Hrvatska

EFFECT OF DIFFERENT COVER MATERIALS FOR »SANDWICH« METHOD

Klančnik¹, J. Habjan¹, M. Drobne¹, P. Mrvar², J. Medved², [1]Valji, d.o.o., Slovenia; 2University of Ljubljana, Faculty of Natural Sciences and Engineering, Slovenia

CHARACTERIZATION OF A MODIFIED INDEFINITE CHILL CAST IRON WORKING LAYER IN ROLLS

Yunus Turen¹,M. Mursel Yildirim, Hayrettin Ahlatci¹, Huseyin Zengin¹, Mehmet Unal¹, Yavuz Sun¹and Mustafa Acarer², ¹Karabuk University, Engineering Faculty, Metallurgy and Materials Engineering, Karabuk TURKEY, ²Selçuk University, Engineering of Technology, Konya, TURKEY

THE EFFECT OF SILICON CONTENT ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF LEAD-FREE BRASS CASTING ALLOYS

Izudin Dugić, Linnaeus University, Faculty of Technology, Department of Mechanical Engineering, Växjö, Sweden

EFFECT OF COOLING RATE ON THE CASTING DEFECTS OF HIGH CHROMIUM WHITE CAST IRON FOR THE IMPELLERS

Abstract

One of the oldest high alloys white cast irons is produced commercially when the chromium

content is between 23 and 28 %. The high-chromium white irons have excellent abrasion resistance and are used effectively in slurry pumps, brick moulds, coal-grinding mills, rolling mill rolls, shot blasting equipment, and components for quarrying, hard-rock mining and milling.

The specifications and requirements applied for the white cast iron components are among the most stringent used within the iron foundry branch. One of the biggest problems for the production of these components is hot tearing or hot cracking, or hot shortness. Irrespective of the name, this phenomenon represents the formation of an irreversible failure (crack) in the still semisolid casting.

This paper will show a study of the effect of cooling rate on the cracks. The procedure to achieve this was to study one casting component, impeller, in a production scale using different cooling rate after pouring.

In this work it has been shown that the solidification rate has a strong effect on the hot cracking.

Črtomir Mikyška¹, Gordana Gojsević Marić², ¹Livar d.d., Ivančna Gorica, Slovenia, ²Elkem AS , Sisak, Hrvatska

EFFECT OF DIFFERENT COVER MATERIALS FOR »SANDWICH« METHOD

Abstract

Based on the current economic situation, there is a need for more cost effective production of ductile iron. In this paper, the main objective was to research the influence of different cover materials in the process of spheroidization treatment on residual magnesium. The comparison was made between a steel cover and a ferrosilicon cover. During tests the samples were examined for metallographic analysis, chemistry and thermal analysis.

Klančnik¹, J. Habjan¹, M. Drobne¹, P. Mrvar², J. Medved², [1]Valji, d.o.o., Slovenia; 2University of Ljubljana, Faculty of Natural Sciences and Engineering, Slovenia

CHARACTERIZATION OF A MODIFIED INDEFINITE CHILL CAST IRON WORKING LAYER IN ROLLS

Abstract

In roll production there is an ever present need for new alloy development and optimization of alloys already in use. The goal is to improve wear resistance while maintaining the level of ductility and other mechanical properties. During the production of cast rolls, the rolls are not subjected to thermo-mechanical processing. Thus an optimal as-cast microstructure is crucial. Addition of heterogeneous nucleation sites into the melt (modification) is a widely used, cost efficient method of improving as-cast mechanical properties of alloys. Powder ferroalloys with a high melting point are an excellent candidate for modification additions.

The effect of melt modification using ferrovanadium and ferrotungsten on as-cast microstructure of indefinite cast iron has been studied. Modifying agents were added in powder form before casting. The modified melt was centrifugally cast in a preheated cylindrical steel mould. Samples were taken directly from the working layer of the roll for metallographic investigation and phase characterization using optical and scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS).

The hardness of the modified working layer showed up to 5% higher values compared to non-modified alloys of similar grade. In fact, the hardness values of the modified indefinite alloy reached those of its more high-alloyed counterparts, while maintaining a lower percentage of cementite. EDS analysis showed the presence of V and W-based precipitates, which have not been confirmed in the non-modified alloys.

THE EFFECT OF SILICON CONTENT ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF LEAD-FREE BRASS CASTING ALLOYS

Abstract

In this study, effect of silicon (Si) additions on mechanical properties of lead-free brass alloys was investigated. Content of silicon in the brass alloys varied between 2 to 4 (% mass fraction). Results showed that additions of silicon increased both ultimate tensile strenght and elangation considerably. The microstructure results show that when Si is added into the lead-free brass alloy, the grain is refined, α + β phase is refined.