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Number of results: 5
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Abstract

This work deals with the problem of intermetallic phases in cast standard duplex steel ASTM A890 Gr 4A (generally known as 2205). The investigated steel was subjected to isothermal heat treatment in the range from 595 °C to 900 °C and in the duration from 15 minutes to 245 hours, and was also investigated in terms of anisothermal (natural) cooling after casting into the mould. The precipitation starts at grain boundaries with a consistent ferrite transformation. The work is focused on the precipitation of the sigma phase (σ) and the chi phase (χ). Examination of the microstructure was conducted using light and scanning electron microscopy. Their statistical analysis was carried out using the results of the investigations of precipitation processes in the microstructure, both within the grains and at the grain boundaries. To illustrate this impact, the surface area of precipitates was evaluated. The percentage of these intermetallic phases was calculated by measuring their area using a computer image analysis system. Based on their observations, a combined time-temperature transformation (TTT) diagram with continuous cooling transformation (CCT) curves was created.
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Authors and Affiliations

M. Myška
1
ORCID: ORCID
P. Bořil
1
ORCID: ORCID
V. Krutiš
1
ORCID: ORCID
V. Kaňa
1
ORCID: ORCID
A. Zádĕra
1
ORCID: ORCID

  1. Brno University of Technology, Czech Republic
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Abstract

The results of investigations of defects in AME-series magnesium alloys produced by the high-pressure die-casting method are presented. The analyzed magnesium alloys contain about 5 wt% aluminum and 1-5 wt% rare earth elements introduced in the form of mischmetal. The casts were fabricated using a regular type cold-chamber high-pressure die-casting machine with a 3.2 MN locking force. The same surfaces of the casts were analyzed before and after the three-point bending test in order to determine the influence of the gas and shrinkage porosity on the deformation behavior of the alloys. The obtained results revealed that the most dangerous for the cast elements is the shrinkage porosity, especially stretched in the direction perpendicular to the that of the tensile stress action. Additionally, the influence of deformation twins arise in the dendrites of the primary α (Mg) solid solution and its interaction on the cracking process was described.
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Authors and Affiliations

Katarzyna Braszczyńska-Malik
ORCID: ORCID

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Abstract

Sand Casting process depends mainly on properties of the green sand mould, sand casting requires requires producing green sand mould without failure and breakage during separation the mould from the model, transportation and handling. Production of the green sand mould corresponding to dimensions and form of the desired model without troubles depends on the properties of the green sand. Ratio of constituents, preparation method of the green sand, mixing and pressing processes determine properties of green sand. In the present work, study effect of the moulding parameters of bentonite content, mixing time, and compactability percentage on the properties of the green sand mould have been investigated. Design of experiments through Taguchi method was used to evaluate properties of permeability, compressive strength, and tensile strength of the green sand. It was found that 47% of compactability, 9(min) of mixing time, and 6% of bentonite content gives highest values of these properties simultaneously.
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Authors and Affiliations

Dheya Abdulamer
1
ORCID: ORCID

  1. University of Technology, Iraq
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Abstract

The paper presents the technology of bimetallic castings using the casting method of applying layers directly during the casting process. The bimetallic casting consists of a load-bearing part (typical casting material, i.e. gray cast iron with flake graphite) and a working part (titanium insert). The titanium insert was made by printing using the selective laser melting (SLM) method, and its shape was spatial. The verification of the bimetallic castings was carried out mainly based on metallographic tests, temperature and thickness measurements. Structure examinations containing metallographic microscopic studies with the use of a light microscope (LOM) and a scanning electron microscope (SEM) with microanalysis of the chemical composition (energy dispersive spectroscopy - EDS).The aim of the tests was to select the appropriate geometrical insert parameters for bimetallic castings within the tested range. The correct parameters of both the insert, pouring temperature and the casting modulus affect the diffusion processes and, consequently, the formation of carbides and the creation of bimetallic castings.
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Authors and Affiliations

A. Dulska
1
ORCID: ORCID

  1. Silesian University of Technology, Faculty of Mechanical Engineering, Department of Foundry Engineering, Towarowa 7, 44-100 Gliwice, Poland
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Abstract

The effect of Ca element on the microstructure evolution of the AZ91 magnesium alloy was investigated in this research. The magne-sium-aluminium alloy AZ91 was inoculated with the Emgesal® Flux 5 to refine its microstructure and also improve its microstructure. Six different concentrations of the Emgesal® Flux 5 content were tested, ranging from 0.1 to 0.6% wt., and compared to the baseline of the AZ91 alloy without inoculation. Melted metal was poured into a preheated metallic mould. Samples to test were achieved after turning treatment. Formed microstructure was assessed using an optical microscope. The microstructure was refined for every tested samples. Me-chanical properties such as tensile strength, elongation, Brinell hardness, Vickers microhardness, abrasion resistance and adhesive resistance were tested on the inoculated samples and compared to the non-inoculated AZ91. Introducing an Emgesal®Flux 5 inoculant caused a change in the tensile strength, elongation, Brinell hard-ness, Vickers microhardness, abrasive wear resistance as well as adhesive wear resistance in each examined concentration.
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Authors and Affiliations

C. Rapiejko
1
ORCID: ORCID
D. Mikusek
1
K. Kubiak
2
ORCID: ORCID
T. Pacyniak
1
ORCID: ORCID

  1. Department of Materials Engineering and Production Systems, Lodz University of Technology, Stefanowskiego 1-15, 90-924 Łódź, Poland
  2. Faculty of Engineering and Physical Sciences, School of Mechanical Engineering, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom

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