The paper presents the evaluation of utility properties of a tube bend produced by bending process using local induction heating technique. Optimal process parameters were defined on the basis of numerical simulations. Mechanical testing procedures for the tube bend were carried out after normalising annealing. Heat treatment parameters have been chosen in compliance with the relevant standard. Geometrical measurements of the bend manufactured under industrial conditions indicate high accuracy of numerical simulations. Geometry and mechanical properties of the produced bend were consistent with the requirements of the applicable standards.
This paper presents the results of measurements of liquid metal fluidity and linear shrinkage of nickel alloy IN-713C in vacuum induction
melting furnace Balzers VSG-2. Because of limited volume of the furnace chamber special models for technological trials were designed
and constructed to fit in the mould of dimensions 170x95x100mm. Two different designs of test models were proposed: horizontal round
rods and modified spiral. Preliminary studies were carried out for alloys Al-Si. Horizontal round rods test was useful for evaluation of
fluidity of hypoeutectic silumin, however in case of nickel superalloy the mould cavity was completely filled in each test because of high
required pouring temperature. Positive results were obtained from the modified spiral test for all alloys used in the research. Relationship
between the linear shrinkage for the test rod and a specific indicator of contraction defined on a spiral was observed.
The study consisted in assessing the influence of surface and volume modification on the characteristics of high-temperature creep of
castings made of waste products of nickel-based superalloys IN 713C and the MAR-247. The results of high-temperature creep tests
performed under conditions of two variants of research were analysed. The characteristics of creep according to variant I were obtained on
the basis of earlier studies of these alloys with the parameters T=982o
C, σ=150MPa [1]. Variant II included carrying out creep tests of
alloy IN713C with the parameters T=760o
C, σ =400MPa and alloy MAR247 with the parameters: T=982o
C, σ=200MPa.Developed creep
characteristics were compared with the results of these alloys with the parameters according to variant I of the study. It was observed that
the conditions of experiments carried out depending upon the value of the creep test temperature and stress with the creep stability depends
on the size of the macrograin (I variant of the studies) or such influence was not observed (II variant of the studies). Stability of samples
with coarse structure in variant I of creep tests was significantly higher than the samples with fragmented grain. It was found that the
observed stability conditions are dependent on the dominant deformation mechanisms under creep tests carried out - diffusion mechanism
in variant I and a dislocation mechanism in variant II of the study. The conditions for the formation and growth of the cracks in the tested
materials, including the morphological characteristics of their macro-and microstructure were tested.
Paper presents the assessment of impact of heat treatment on durability in low-cycle fatigue conditions (under constant load) in castings
made using post-production scrap of MAR-247 and IN-713C superalloys. Castings were obtained using modification and filtration
methods. Additionally, casting made of MAR-247 were subjected to heat treatment consisting of solution treatment and subsequent aging.
During low-cycle fatigue test the cyclic creep process were observed. It was demonstrated that the fine-grained samples have significantly
higher durability in test conditions and , at the same time, lower values of plastic deformation to rupture Δϵpl. It has been also proven that
durability of fine-grained MAR-247 samples can be further raised by about 60% using aforementioned heat treatment.
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