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Number of results: 12
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Abstract

An innovative method for determining the structural zones in the large static steel ingots has been described. It is based on the

mathematical interpretation of some functions obtained due to simulation of temperature field and thermal gradient field for solidifying

massive ingot. The method is associated with the extrema of an analyzed function and with its points of inflection. Particularly, the CET

transformation is predicted as a time-consuming transition from the columnar- into equiaxed structure. The equations dealing with heat

transfer balance for the continuous casting are presented and used for the simulation of temperature field in the solidifying virtual static

brass ingot. The developed method for the prediction of structural zones formation is applied to determine these zones in the solidifying

brass static ingot. Some differences / similarities between structure formation during solidification of the steel static ingot and virtual brass

static ingot are studied. The developed method allows to predict the following structural zones: fine columnar grains zone, (FC), columnar

grains zone, (C), equiaxed grains zone, (E). The FCCT-transformation and CET-transformation are forecast as sharp transitions of the

analyzed structures. Similarities between steel static ingot morphology and that predicted for the virtual brass static ingot are described.

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Authors and Affiliations

A.A. Ivanova
B. Kania
P. Kwapisiński
W. Wołczyński
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Abstract

A vertical cut at the mid-depth of the 15-ton forging steel ingot has been performed by curtesy of the CELSA – Huta Ostrowiec plant.

Some metallographic studies were able to reveal not only the chilled undersized grains under the ingot surface but columnar grains and

large equiaxed grains as well. Additionally, the structural zone within which the competition between columnar and equiaxed structure

formation was confirmed by metallography study, was also revealed. Therefore, it seemed justified to reproduce some of the observed

structural zones by means of numerical calculation of the temperature field. The formation of the chilled grains zone is the result of

unconstrained rapid solidification and was not subject of simulation. Contrary to the equiaxed structure formation, the columnar structure

or columnar branched structure formation occurs under steep thermal gradient. Thus, the performed simulation is able to separate both

discussed structural zones and indicate their localization along the ingot radius as well as their appearance in term of solidification time.

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Authors and Affiliations

W. Skuza
B. Kania
P. Kwapisiński
W. Wołczyński
A.W. Bydałek
W. Wajda
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Abstract

Two MgLiAl alloys of composition 4.5% Li and 1.5% Al (in wt.%) composed of α phase and of 9% Li, 1.5% Al composed of α (hcp) + β (bcc) phases were subjected to twist channel angular pressing (TCAP) deformation. Such deformation of α + β alloys caused less effective grain refinement than that of single α phase alloy. However, with increasing number of passes, grain size of single α phase alloy increased and that of β phase in two phase α + β alloy also grew, which suggested the effect of dynamic recrystallization. TEM studies allowed identifying particles of Li2MgAl phase of size of few μm. {001}<100> texture was observed in extruded alloy. Texture studies of extruded and TCAPed single phase hcp alloy indicated texture with {101 – 0} plane perpendicular to the extrusion direction and {0002} plane parallel to the extrusion direction. Duplex α + β alloys showed poor texture development.

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Authors and Affiliations

J. Dutkiewicz
S. Rusz
D. Kuc
O. Hilser
P. Bobrowski
B. Kania
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Abstract

The paper, which is a summary and supplement of previous works and research, presents the results of numerical and physical modeling of the GX2CrNiMoCuN25-6-3 duplex cast steel thin-walled castings production. To obtain thin-walled castings with wall in the thinnest place even below 1 mm was used the centrifugal casting technology and gravity casting. The analyzed technology (centrifugal casting) enables making elements with high surface quality with reduced consumption of batch materials and, as a result, reducing the costs of making a unitary casting. The idea behind the production of cast steel with the use of centrifugal technology was to find a remedy for the problems associated with unsatisfactory castability of the tested alloy.

The technological evaluation of the cast construction was carried out using the Nova Flow & Solid CV 4.3r8 software. Numerical simulations of crystallization and cooling were carried out for a casting without a gating system and sinkhead located in a mold in accordance with the pouring position. It was assumed that the analyzed cast will be made in the sand form with dimensions 250×250×120 mm.

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Authors and Affiliations

G. Stradomski
M. Nadolski
ORCID: ORCID
A. Zyska
B. Kania
D. Rydz
ORCID: ORCID
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Abstract

Industries that rely on additive manufacturing of metallic parts, especially biomedical companies, require material science-based knowledge of how process parameters and methods affect the properties of manufactured elements, but such phenomena are incompletely understood. In this study, we investigated the influence of selective laser melting (SLM) process parameters and additional heat treatment on mechanical properties. The research included structural analysis of residual stress, microstructure, and scleronomic hardness in low-depth measurements. Tensile tests with specimen deformation analysis using digital image correlation (DIC) were performed as well. Experiment results showed it was possible to observe the porosity growth mechanism and its influence on the material strength. Specimens manufactured with 20% lower energy density had almost half the elongation, which was directly connected with the porosity growth during energy density reduction. Hot isostatic pressing (HIP) treatment allowed for a significant reduction of porosity and helped achieve properties similar to specimens manufactured using different levels of energy density.

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Authors and Affiliations

J. Kluczyński
L. Śnieżek
ORCID: ORCID
K. Grzelak
ORCID: ORCID
A. Oziębło
K. Perkowski
J. Torzewski
I. Szachogłuchowicz
K. Gocman
M. Wachowski
ORCID: ORCID
B. Kania

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