Livarski vestnik 53 / 2006 Nr. 3
Jožef Medved, Primož Mrvar:
High-Temperature Oxidation of Mg Alloys
Svein Oddvar Olsen:
Precipitation Strengthening of Pearlitic Ductile Iron
D. Zadnek; P. Mrvar; J. Medved, J. Pristavec, G. Kugler:
Development of the Control Methodfor Determination of Properties of Exothermic Mixtures - Entering Data for the Casting Simulation
High-Temperature Oxidation of Mg Alloys
Abstract
The purpose of present work was to examine the oxidation of Mg-Al alloys in the atmospherer of oxygen at various temperatures, next to thermodynamic analysis of magnesium alloys with varying amounts of aluminium. The basic examination methods were differential scanning calorimetry and thermogravimetry. The latter is based on recording the variation of sample mass as a function of temperature. Oxidation process was analysed by the differential scanning calorimetry.
The results show that the oxide layer can protect material against progressive oxidation or it causes complete disintegration of material. The nature of oxide layer depends on the external conditions, i.e. on atmosphere, temperature and type of the alloy.
From TG curves it was calculated a model of the Mg-Al alloy oxidation: Δ m=5E-0,5t3 - 0,0022t2 - 0,0315t + 100,01 [mas. %] prevention oxidation Δ m=0,159t4-2,0942t3+103,72 t2 -2277,8 t +118597 [mas. %] propagation oxidation By heating of materials because of charge preheating, thermal treatment or any other reason must be temperature lover than temperature of incipient fusion of eutectic phase (lover than 400 °C).
Key words: Mg - alloys, oxidation, thermodynamics, thermal analyses
The results show that the oxide layer can protect material against progressive oxidation or it causes complete disintegration of material. The nature of oxide layer depends on the external conditions, i.e. on atmosphere, temperature and type of the alloy.
From TG curves it was calculated a model of the Mg-Al alloy oxidation: Δ m=5E-0,5t3 - 0,0022t2 - 0,0315t + 100,01 [mas. %] prevention oxidation Δ m=0,159t4-2,0942t3+103,72 t2 -2277,8 t +118597 [mas. %] propagation oxidation By heating of materials because of charge preheating, thermal treatment or any other reason must be temperature lover than temperature of incipient fusion of eutectic phase (lover than 400 °C).
Key words: Mg - alloys, oxidation, thermodynamics, thermal analyses
Precipitation Strengthening of Pearlitic Ductile Iron
Abstract
The objective of this paper is to review some possible ways to increase the mechanical properties of pearlitic ductile iron. The paper will concentrate on the effect of Vanadium as an alloying element in an “in the mould” treatment and an ordinary ladle process for ductile iron production.
The results from mechanical tests will be given and the difference between the two processes is compared with an unalloyed iron as a reference.
The results from mechanical tests will be given and the difference between the two processes is compared with an unalloyed iron as a reference.
D. Zadnek; P. Mrvar; J. Medved, J. Pristavec, G. Kugler:
Development of the Control Methodfor Determination of
Properties of Exothermic Mixtures - Entering Data for the
Casting Simulation
Properties of Exothermic Mixtures - Entering Data for the
Casting Simulation
Summary
Modern to progress and economical business oriented foundries in aspiartion for production of quality and competitive benefi t prices of castings, apply new methods of planning and development. Economical casting means bigger take out - proportion between mass of quality castings and total mass of casted metal (including gating and feeding system). Feeding is more economical and effective with application of feeder linings - exothermic, insulating or such with combined effect.
In last time, more and more computer simulation of casting and solidifi cation is used between development process. In data base of such simulation package are included almost all known casting materials, moulding materials and auxiliary materials (exothermic agents, linings, strew powder materials, coatings). This data are in many cases only approximate values of their characteristics, particularly in case of auxiliary agents (exothermic mixtures).
Intention of this work is presentation of the method of testing of characteristics of exothermic mixtures and exothermic - insulating linings. Acquired data will be applied as quality control in a production of exothermal mixtures and as supplement of data base in simulation package of casting and solidifi cation MAGMASOFT ®. Using this method we can also improve properties and functional effects of those materials and easier perform requests of users.
Key words: exothermic mixtures, exothermic linings, warming feeders, simulation of
casting and solidifi cation, optimization of casting
In last time, more and more computer simulation of casting and solidifi cation is used between development process. In data base of such simulation package are included almost all known casting materials, moulding materials and auxiliary materials (exothermic agents, linings, strew powder materials, coatings). This data are in many cases only approximate values of their characteristics, particularly in case of auxiliary agents (exothermic mixtures).
Intention of this work is presentation of the method of testing of characteristics of exothermic mixtures and exothermic - insulating linings. Acquired data will be applied as quality control in a production of exothermal mixtures and as supplement of data base in simulation package of casting and solidifi cation MAGMASOFT ®. Using this method we can also improve properties and functional effects of those materials and easier perform requests of users.
Key words: exothermic mixtures, exothermic linings, warming feeders, simulation of
casting and solidifi cation, optimization of casting