The presented access the influence of Mn content (0-0.94 wt.%) on the course of the cooling curves, phase transformation, macrostructure, and microstructure of Al-Cu alloys for three series: initial (Series I), with the addition of an AlTi master (Series II), and modified with AlTi5B1 (Series III). The maximum degree of undercooling ΔT was determined based on the cooling curves. The surface density of the grains (NA) was determined and associated with the inverse of solidification interval 1/ΔTk. Titanium (contained in the charge materials as well as the modifier) has a significant effect on the grinding of the primary grains in the tested alloys. A DSC thermal analysis allowed for the determination of phase transition temperatures under conditions close to equilibrium. For series II and III, the number of grains decreases above 0.2 wt.% Mn with a simultaneous increase in solidification interval 1/ΔTk. The presence of Al2Cu eutectics as well as the Cu-, Fe-, and Mn-containing phases in the examined samples was demonstrated using scanning electron microscopy.

Structure, and thus the mechanical properties of steel are primarily a function of chemical composition and the solidification process which can be influenced by the application of the inoculation treatment. This effect depends on the modifier used. The article presents the results of studies designed to assess the effects of structural low alloy steel inoculation by selected modifying additives. The study was performed on nine casts modeled with different inoculants, assessment of the procedure impact was based on the macrostructure of made castings. The ratio of surface area equivalent to the axial zone of the crystals and columnar crystals zone was adopted as a measure of the inoculation effect.

Impact of surface and volume modification and double filtration during pouring the moulds on basic mechanical properties and creep resistance of nickel superalloys IN-713C and MAR-247 in conditions of accelerated creep of castings made of post-production scrap of these alloys is evaluated in this paper. The conditions of initiation and propagation of cracks in the specimens were analysed with consideration of stereological properties of material macro- and microstructure. It has been proven that in the conditions of hightemperature creep at 980°C and at stress σ = 150 MPa, creep resistance of superalloy MAR-247 is more than 10 times higher than the creep resistance of IN-713C alloy. In case of IN-713C alloy, the creep resistance negligibly depends on macrograin sizes. But, the macrograin size considerably affects the time to failure of specimens made of alloy MAR-247. Creep resistance of specimens made of coarse grain material was 20% higher than the resistance of fine grain materials.

The development of power industry obligates designers, materials engineers to create and implement new, advanced materials, in which Inconel 617 alloy is included. Nowadays, there are a lot of projects which describe microstructure and properties of Inconel 617 alloy. However, the welded joints from mentioned material is not yet fully discussed in the literature. The description of welded joints microstructure is a main knowledge source for designers, constructors and welding engineers in estimating durability process and degradation assessment for elements and devices with welds of Inconel 617 alloy. This paper presents the analysis and assessment of advanced nickel alloy welded joints, which have been done by tungsten inert gas (TIG). Investigations have included analysis made by light microscope and scanning electron microscope. The disclosed precipitates were identified with Energy Dispersive Spectroscopy (EDS) microanalysis, then it were done X-Ray Diffraction (XRD) phases analysis. To confirm the obtained results, a scanning-transmission electron microscope (STEM) analysis was also performed.

The purpose of the article was to create a comprehensive procedure for revealing the Inconel 617 alloy structure. The methodology presented in this article will be in future a great help for constructors, material specialists and welding engineers in assessing the structure and durability of the Inconel 617 alloy.

The paper presents the results of studies to determine the effect of complex surface and bulk modification and double filtration during mould pouring on the stereological parameters of macrostructure and mechanical properties of castings made from the post-production waste IN-713C and the MAR-247 nickel alloys. The evaluation covered the number of grains per 1mm2 of the sample surface area, the average area of grains and the shape index, hardness HB, tensile strength and resistance to high temperature creep. The results indicate the possibility of controlling the stereological parameters of macrostructure through application of several variants of the modification, controlling in this way also different low- and high-temperature properties. The positive effect of double filtration of the alloy during mould pouring on the metallurgical quality and mechanical properties of castings has also been emphasized.

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.

The paper presents the results of research on the determination of the effect of pouring temperature on the macrostructure of the castings

subjected to complex (surface and volume) modification and double filtration. Tested castings were made of post-production scrap (gating

system parts) of IN-713C superalloy. Tests included the evaluation of the number of grains per 1 mm2

, mean grain surface area, shape

factor and tensile strength. Casting temperature below 1470 °C positively influenced the modification effect. The grains were finer and the

mechanical properties increased, especially for castings with thicker walls. On the other hand, manufacture of thin walled castings of high

quality require pouring temperature above 1480 °C.

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.

In current casting technology of cored, thin walled castings, the modifying coating is applied on the surface of wax pattern and, after the

removal of the wax, is transferred to inner mould surface. This way the modification leading to grain refinement occur on the surface of

the casting. In thin walled castings the modification effect can also be seen on the other (external) side of the casting. Proper reproduction

of details in thin walled castings require high pouring temperature which intensify the chemical reactions on the mould – molten metal

interface. This may lead to degradation of the surface of the castings. The core modification process is thought to circumvent this problem.

The modifying coating is applied to the surface of the core. The degradation of internal surface of the casting is less relevant. The most

important factor in this technology is “trough” modification – obtaining fine grained structure on the surface opposite to the surface

reproduced by the core.

Paper presents the results of research on modified surface grain refinement method used in investment casting of hollow, thin-walled parts

made of nickel based superalloys. In the current technology, the refining inoculant is applied to the surface of the wax pattern and then, it

is transferred to the ceramic mould surface during dewaxing. Because of its chemical activity the inoculant may react with the liquid metal

which can cause defects on the external surface of the cast part. The method proposed in the paper aims to reduce the risk of external

surface defects by applying the grain refiner only to the ceramic core which shapes the internal surface of the hollow casting. In case of

thin-walled parts the grain refinement effect is visible throughout the thickness of the walls. The method is meant to be used when internal

surface finish is less important, like for example, aircraft engine turbine blades, where the hollowing of the cast is mainly used to lower the

weight and aid in cooling during operation.

The work reports on the development of random three-dimensional Laguerre-Voronoi computational models for open cell foams. The proposed method can accurately generate foam models having randomly distributed parameter values. A three-dimensional model of ceramic foams having pre-selected cell volumes distribution with stochastic coordinates and orientations was created in the software package ANSYSTM. Different groups of finite element models were then generated using the developed foam modeling procedure. The size sensitivity study shows that each of foam specimens at least contains 125 LV-cells. The developed foam models were used to simulate the macroscopic elastic properties of open cell foams under uni-axial and bi-axial loading and were compared with the existing open cell foam models in the literature. In the high porosity regime, it is found that the elastic properties predicted by random Laguerre-Voronoi foam models are almost the same as those predicted by the perfect Kelvin foam models. In the low porosity regime the results of the present work deviate significantly from those of other models in the literature. The results presented here are generally in better agreement with experimental data than other models. Thus, the Laguerre-Voronoi foam models generated in this work are quite close to real foam topology and yields more accurate results than other open cell foam models.

The paper presents the results concerning impact of modification (volume and surface techniques), pouring temperature and mould

temperature on stereological parameters of macrostructure in IN713C castings made using post-production scrap. The ability to adjust the

grain size is one of the main issues in the manufacturing of different nickel superalloy castings used in aircraft engines. By increasing the

grain size one can increase the mechanical properties, like diffusion creep resistance, in higher temperatures. The fine grained castings. on

the other hand, have higher mechanical properties in lower temperatures and higher resistance to thermal fatigue. The test moulds used in

this study, supplied by Pratt and Whitney Rzeszow, are ordinarily used to cast the samples for tensile stress testing. Volume modification

was carried out using the patented filter containing cobalt aluminate. The macrostructure was described using the number of grains per

mm2

, mean grain surface area and shape index. Obtained results show strong relationship between the modification technique, pouring

temperature and grain size. There was no significant impact of mould temperature on macrostructure.