Fikret Kabakcı¹, Mustafa Acarer², Selçuk Keskinkılıç³ and Filiz Kumdalı Acar³TOUGHNESS OF P91 BASE AND WELD METAL

Lavtar¹, M. Petrič², B. Taljat¹, S. Kastelic², P. Mrvar²OPTIMIZATION OF COOLING-HEATING SYSTEM IN HPDC TOOLS

Maja Vončina¹, Terezija Poženel², Mitja Petrič¹, Primož Mrvar¹, Jožef Medved¹INFLUENCE OF FOUNDRY DEFECTS ON THE ELECTRICAL PROPERTIES OF Al-CASTINGS

Kugler^a, P. Mrvar^a, M. Petrič^a, A. Križman^a in M. Terčelj^a[1]IMPROVING THE MECHANICAL PROPERTIES OF AM60 FOUNDRY ALLOY

Fikret Kabakcı1, Mustafa Acarer2, Selçuk Keskinkılıç3 and Filiz Kumdalı Acar3
TOUGHNESS OF P91 BASE AND WELD METAL

ABSTRACT

P91 CrMo steel is extensively used at elevated temperature applications in fossil fire and nuclear power plants for tube and piping due to its excellent creep and oxidation resistance. Also they should have acceptable weldability and toughness. In this study microstructure and toughness properties of P91 base and weld metal were investigated. The ductile-brittle transition temperature (DBTT) of P91 base metal was also figured out. The microstructures of the base and weld metal have martensite and tempered martensite and some precipitates. In the (DBTT) test, toughness of P91 steel as base metal was observed as high as 80J even at -60 ^oC. Toughness of P91 weld metal has 92 Joule at room temperature.

Lavtar¹, M. Petrič², B. Taljat¹, S. Kastelic², P. Mrvar²OPTIMIZATION OF COOLING-HEATING SYSTEM IN HPDC TOOLS

Abstract

High pressure die-casting process (HPDC) is a permanent mould casting technology. During one cycle the melts' heat is transported into a steel tool which is a reason for the heating of a tool. In order to prevent overheating the heating-cooling system is positioned in the tool. Cooling-heating system heats up the tool at the beginning of the casting process and cools the tool in further production of castings. The paper describes the problems of the conventional tool with defect analysis as a result of thermal loading. Based on the analysis of the existing tool made by ProCAST software the change of the heating-cooling system in a tool was prepared and verified. In further the new tool was produced.

Maja Vončina¹, Terezija Poženel², Mitja Petrič¹, Primož Mrvar¹, Jožef Medved¹INFLUENCE OF FOUNDRY DEFECTS ON THE ELECTRICAL PROPERTIES OF Al-CASTINGS

Abstract

The current aluminium high-pressure die casting technology for casting rotor squirrel cages of induction motor has to satisfy the requirements of high productivity, but does not satisfy the largest possible total efficiency of electric motors. With this aim the influence of casting defects, such as impurities and porosity, on the electrical properties of the cast aluminium was investigated. The specimens were cast from the Al-alloys Al99.99, Al99.7, Al99.5 and under various casting conditions, such as in the vacuum and in air. During the solidification, temperature and electrical conductivity of the castings were measured. Samples were analysed using an optical microscope to determine the proportion of the porosity in the castings, and using scanning electron microscope (SEM) to examine the phases and impurities in the castings. Based on these results the influence of impurities and porosity of the electrical properties of aluminium was explained.

Kugler^a, P. Mrvar^a, M. Petrič^a, A. Križman^a in M. Terčelj^a[2]
IMPROVING THE MECHANICAL PROPERTIES OF AM60 FOUNDRY ALLOY

Abstract

MgAl6Mn alloy is usually used for casting and improving of its mechanical properties. It is usually achieved by various heat treatment procedures after casting. This study was focused on the possibility to improve the mechanical properties of MgAl6Mn alloy by imposingthe small hot deformation on a selected area of casting after completed solidification. This cast material solidified with cooling rates of 2, 7 and 50 K/min, respectively. Then appropriate conditions for hot working were found using compression tests in the temperature range between 200-450°C, strain rates range 0.001-10s^-1 and strain of 0.8 for each as-cast state. On samples made from cast blocks small hot deformations of true strain in the range between 0.1 - 0.4 using previously assessed appropriate temperature and strain rate ranges were imposed and mechanical properties so by tensile as well as by Charpy tests were determined. Three times increase of tensile strength was obtained for samples with imposed small hot deformation and cooling rates at solidification of 7K/min and above.

[1] Ustrezni avtor: e-pošta: Milan.Tercelj@ntf.uni-lj.si; tel.: +386 1 4704 506; faks: +386 1 4704 560

[2] Ustrezni avtor: e-pošta: Milan.Tercelj@ntf.uni-lj.si; tel.: +386 1 4704 506; faks: +386 1 4704 560