Abstract
Inconel 713C is a nickel-based casting alloy characterised by improved heat and creep resistance [1]. It is used e.g. in aircraft engine
components, mainly in the form of precision castings. Precision casting enables very good reproduction of complex shapes. However, due
to major differences in casting wall thickness and the resultant differences in rigidity, defects can form in precision castings. The most
common defects in precision castings are shrinkage porosities and microcracks.
Inconel 713C is considered to be a difficult-to-weld or even non-weldable alloy. However, the need to repair precision castings requires
attempts to develop technologies for their remelting and pad welding which could be used in industrial practice. This article presents the
results of tests consisting in TIG pad welding of defects identified in precision castings intended for the aircraft industry. It was found that
the main reason behind failed attempts at repairing precision castings by welding technologies was hot cracking in the fusion zone. Such
cracks form as a result of the partial melting of intercrystalline regions along the fusion line. The deformations occurring during the
crystallization of the melting-affected zone (fusion zone + partially melted zone + heat affected zone) or pad weld lead to the rupture of the
intercrystalline liquid film. Hot cracks form within the so-called high-temperature brittleness range (HTBR) of the alloy. Another type of
cracks that was identified were ductility dip cracks (DDC), whose formation is related to the partial melting of carbides.
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