Details

Title

The Effect of Shell Thickness, Insulation and Casting Temperature on Defects Formation During Investment Casting of Ni-base Turbine Blades

Journal title

Archives of Foundry Engineering

Yearbook

2015

Numer

No 4

Publication authors

Keywords

Investment casting ; Casting defects ; Shrinkage porosity ; Grain structure ; Turbine blades ; Niyama criterion

Divisions of PAS

Nauki Techniczne

Description

Archives of Foundry Engineering continues the publishing activity started by Foundry Commission of the Polish Academy of Sciences (PAN) in Katowice in 1978. The initiator of it was the first Chairman Professor Dr Eng. Wacław Sakwa – Corresponding Member of PAN, Honorary Doctor of Czestochowa University of Technology and Silesian University of Technology. This periodical first name was „Solidification of Metals and Alloys” , and made possible to publish the results of works achieved in the field of the Basic Problems Research Cooperation. The subject of publications was related to the title of the periodical and concerned widely understand problems of metals and alloys crystallization in a casting mold. In 1978-2000 the 44 issues have been published. Since 2001 the Foundry Commission has had patronage of the annually published “Archives of Foundry” and since 2007 quarterly published “Archives of Foundry Engineering”. Thematic scope includes scientific issues of foundry industry:

  • Theoretical Aspects of Casting Processes,
  • Innovative Foundry Technologies and Materials,
  • Foundry Processes Computer Aiding,
  • Mechanization, Automation and Robotics in Foundry,
  • Transport Systems in Foundry,
  • Castings Quality Management,
  • Environmental Protection.

Abstract

Turbine blades have complex geometries with free form surface. Blades have different thickness at the trailing and leading edges as well

as sharp bends at the chord-tip shroud junction and sharp fins at the tip shroud. In investment casting of blades, shrinkage at the tip-shroud

and cord junction is a common casting problem. Because of high temperature applications, grain structure is also critical in these castings

in order to avoid creep. The aim of this work is to evaluate the effect of different process parameters, such as, shell thickness, insulation

and casting temperature on shrinkage porosity and grain size. The test geometry used in this study was a thin-walled air-foil structure

which is representative of a typical hot-gas-path rotating turbine component. It was observed that, in thin sections, increased shell

thickness helps to increase the feeding distance and thus avoid interdendritic shrinkage. It was also observed that grain size is not

significantly affected by shell thickness in thin sections. Slower cooling rate due to the added insulation and steeper thermal gradient at

metal mold interface induced by the thicker shell not only helps to avoid shrinkage porosity but also increases fill-ability in thinner

sections.

Publisher

The Katowice Branch of the Polish Academy of Sciences

Date

2015[2015.01.01 AD - 2015.12.31 AD]

Type

Artykuły / Articles

Identifier

ISSN 2299-2944

DOI

10.1515/afe-2015-0090

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