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Abstract

Inconel 713C precision castings are used as aircraft engine components exposed to high temperatures and the aggressive exhaust gas

environment. Industrial experience has shown that precision-cast components of such complexity contain casting defects like

microshrinkage, porosity, and cracks. This necessitates the development of repair technologies for castings of this type. This paper

presents the results of metallographic examinations of melted areas and clad welds on the Inconel 713C nickel-based superalloy, made by

TIG, plasma arc, and laser. The cladding process was carried out on model test plates in order to determine the technological and materialrelated

problems connected with the weldability of Inconel 713C. The studies included analyses of the macro- and microstructure of the

clad welds, the base materials, and the heat-affected zones. The results of the structural analyses of the clad welds indicate that Inconel

713C should be classified as a low-weldability material. In the clad welds made by laser, cracks were identified mainly in the heat-affected

zone and at the melted zone interface, crystals were formed on partially-melted grains. Cracks of this type were not identified in the clad

welds made using the plasma-arc method. It has been concluded that due to the possibility of manual cladding and the absence of welding

imperfections, the technology having the greatest potential for application is plasma-arc cladding.

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Authors and Affiliations

J. Adamiec
K. Łyczkowska
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Abstract

The paper presents the results of research on the microstructure of GX2CrNiMoCuN25-6-3-3 and GX2CrNiMoCuN25-6-3 cast steels with

a varying carbon content. The cause for undertaking the research were technological problems with hot cracking in bulk castings of duplex

cast steel with a carbon content of approx. 0.06% and with 23% Cr, 8.5% Ni, 3% Mo and 2.4% Cu. The research has shown

a significant effect of increased carbon content on the ferrite and austenite microstructure morphology, while exceeding the carbon content

of 0.06% results in a change of the shape of primary grains from equiaxial to columnar.

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Authors and Affiliations

G. Stradomski
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Abstract

In the paper, verification of welding process parameters of overlap joints of aluminium alloys EN AW-6082 and EN AW-7075, determined on the grounds of a numerical FEM model and a mathematical model, is presented. A model was prepared in order to determine the range of process parameters, for that the risk of hot crack occurrence during welding the material with limited weldability (EN AW-7075) would be minimum and the joints will meet the quality criteria. Results of metallographic and mechanical examinations of overlap welded joints are presented. Indicated are different destruction mechanisms of overlap and butt joints, as well as significant differences in their tensile strength: 110 to 135 MPa for overlap joints and 258 MPa on average for butt joints.

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Authors and Affiliations

T. Wojdat
ORCID: ORCID
P. Kustroń
K. Jaśkiewicz
M. Zwierzchowski
A. Margielewska
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Abstract

Nickel alloys, despite their good strength properties at high temperature, are characterized by limited weldability due to their susceptibility to hot cracking. So far, theories describing the causes of hot cracking have focused on the presence of impurities in the form of sulphur and phosphorus. These elements form low-melting eutectic mixtures that cause discontinuities, most frequently along solid solution grain boundaries, under the influence of welding deformations. Progress in metallurgy has effectively reduced the presence of sulphur and phosphorus compounds in the material, however, the phenomenon of hot cracking continues to be the main problem during the welding of nickel-based alloys. It was determined that nickel-based alloys, including Inconel 617, show a tendency towards hot cracking within the high-temperature brittleness range (HTBR). There is no information on any structural changes occurring in the HTBR. Moreover, the literature indicates no correlations between material-related factors connected with structural changes and the amount of energy delivered into the material during welding.

This article presents identification of correlations between these factors contributes to the exploration of the mechanism of hot cracking in solid-solution strengthened alloys with an addition of cobalt (e.g. Inconel 617). The article was ended with development of hot cracking model for Ni-Cr-Mo-Co alloys.

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Authors and Affiliations

J. Adamiec
N. Konieczna

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