Izudin Dugic

Modelling of volumes in cast iron solidification to predict shrinkage and expansion defects.

Modelling of volumes in cast iron solidification to predict shrinkage and expansion defects.

Defect Formation of Gray Iron Casting

Cast iron is one of the oldest technical alloys (engineered cast materials) used for creating objects. From the very beginning of casting, foundrymen were fighting to avoid casting defects. In the beginning a successfully produced casting was associated with witchcraft. Cast component producers suffer substantial yearly expenses due to rejecting or repairing castings. This present work will summarize research efforts to understand the formation mechanisms of defects, performed in collaboration with Swedish foundries during the last few years. It will focus on defects specific to the casting of gray iron components and the studied defects: gas porosity, shrinkage porosity and metal expansion penetration. Novell experimental set up has been developed or existing methods have been improved to study defect formation mechanisms. Today we can realize that casting without defects is possible only by approaching the defect formation mechanism with multidisciplinary science.

An investigation of the effect of inoculants on the metal expansion penetration in grey iron

An investigation of the effect of inoculants on the metal expansion penetration in grey iron

Defect formation mechanisms in lamellar graphite iron related to the casting geometry

Abstract Although lamellar cast iron has been used in advanced applications for about 20 years, our knowledge about the mechanisms affecting microstructure and defect formation is relatively limited. The present paper summarises some solidification-related phenomena from a series of recently published peer-reviewed papers and scientific theses and suggests a mechanism of defect formation which is dependent on the shape of the solidifying casting geometry. When shrinkage porosity or metal expansion penetration occurs, evidence of material transport in the intergranular zone of primary equiaxed austenite grains in the casting and in the intergranular regions between the sand grains in the mould material is seen. Material transport occurs across the casting-mould interface, where the existence of or the permeability of the primary columnar zone determines if material transport can take place.

Non-metallic Inclusion and Their Effect on Fatigue Strength for Case-Hardened Carbon Steel in Gears

Steel is a very essential structural material and its production worldwide has shown significant increase over the last years. In steels there always exist a large number of inclusions which can have a degrading effect on the fatigue properties. This study is focused on the link between the characteristics of non-metallic inclusions and how they affect fatigue strength of the standardized case-hardened carbon steel 20MnCr5 and a version of this steel with a more favorable inclusion distribution, a so-called Clean steel. For the evaluation of the mechanical properties the test result from rotary bending tests are compared and an improvement by 37.5% in fatigue strength can be noted between the different steels. The new performed ultrasonic tests illustrate the difference in the size of defects in materials with different manufacturing processes and degree of reduction. By studying international and European standards for non-destructive testing and investigation of alloy compounds, the current material specification can be adjusted.

Effect of Molybdenum Content, Pouring Temperature and Cooling Rate on the Casting Defects of High Chromium White Cast Iron

High chromium white cast are commonly used in application requiring excellent abrasion resistance, as central parts for pumps. 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. Irrespective of the name, this phenomenon represents the formation of an irreversible failure (crack) in the still semisolid casting. This paper aims to investigate the effect of molybdenum content, pouring temperature and cooling rate on the casting defect hot tearing. The procedure to achieve this was to study one casting component, impeller, in a production scale. The experiments showed that molybdenum content and pouring temperature had an important influence on casting defects. It was also observed that the solidification rate has a strong effect on the hot cracking.

On the Effect of Alloying Element Range on the Mechanical Properties of Recycled Aluminium Alloy EN AB-46000

Aluminium can be produced from the raw material bauxite or by recycling aluminium scrap. When aluminium is being recycled, the material strength is then depending on the alloying and trace elements ...