The paper covers the research on the process of solutionizing of 7075 aluminum alloy in cold tools during the stamping of a high-strength structural element (B-pillar’s base). For technological reasons, in order to obtain high strength parameters of the 7075 alloy, it is necessary to carry out a solutionization process, which allows to obtain dispersion strengthening during ageing process. Properly performed heat treatment of the alloy increases the strength of the material to approx. 600 MPa. The combination of the process of solutionization with simultaneous shaping is aimed at improving and simplifying technological operations of aluminum alloy stamping, shortening the duration of the manufacturing process and reducing production costs. The manufactured lower part of the B-pillar will be used for the verification of the validity of the developed method. During the experiment, a series of stamping tests were carried out, in which the lubricants, pressure and position of the upper and lower blankholders were the variables. The obtained results allow to estimate the influence of the cooling conditions on the strength of the drawpieces obtained after the process of artificial ageing. In order to verify and analyse the results more quickly, a numerical simulation was carried out.

Main aim of submitted work is evaluation and experimental verification of inoculation effect on Al alloys hot-tear sensitivity. Submitted work consists of two parts. The first part introduces the reader to the hot tearing in general and provides theoretical analysis of hot tearing phenomenon. The second part describes strontium effect on hot tearing susceptibility, and gives the results on hot tearing for various aluminium alloys. During the test, the effect of alloy chemical composition on hot tearing susceptibility was also analyzed. Two different Al-based alloys were examined. Conclusions deals with effect of strontium on hot tearing susceptibility and confirms that main objective was achieved.

The article reports the results of a comparative analysis made for three novel unconventional gear wheel forging processes based on the authors’ patented [5,6,21] plastic forming methods developed chiefly for the purposes of extruding hollow products as well as valves and pins. These processes are distinguished by the fact that part of the tooling elements which are normally fixed during conventional forging are purposefully set in motion. This is intended to change the conditions of friction at the metal-tool contact surface and to induce additional thermal effects due to the transformation of the plastic deformation energy into thermal energy and, as a consequence, to improve the plastic flow of metal and to reduce the force parameters of the process.

This paper discusses the mechanical properties of a material fabricated from commercially available metal powder mixtures designed for

use as a metal matrix of diamond impregnated composites. The mixtures with the catalogue numbers CSA and CSA800 provided by a

Chinese producer are suitable for experimental laboratory testing. The specimens were fabricated in a graphite mould using hot pressing.

The material was tested for density, porosity, hardness, and tensile strength under static loading. A scanning electron microscope (SEM)

was used to analyze the microstructure and cleavage fracture of broken specimens. It was essential to determine how the chemical

composition and the fabrication process affected the microstructure and properties of the material. The properties of the sinters were

compared with those of hot pressed specimens fabricated from sub-micron size cobalt powder (Cobalt SMS). Although the as-consolidated

material is inferior to cobalt, it displays a favourable combination of hardness, yield strength and ductility, and seems to have a great

potential for moderate and general purpose applications.

The paper presents the results of investigations of the growth of protective coating on the surface of ductile iron casting during the hot-dip

galvanizing treatment. Ductile iron of the EN-GJS-600-3 grade was melted and two moulds made by different technologies were poured to

obtain castings with different surface roughness parameters. After the determination of surface roughness, the hot-dip galvanizing

treatment was carried out. Based on the results of investigations, the effect of casting surface roughness on the kinetics of the zinc coating

growth was evaluated. It was found that surface roughness exerts an important effect on the thickness of produced zinc coating

The investigations were inspired with the problem of cracking of steel castings during the production process. A single mechanism

of decohesion – the intergranular one – occurs in the case of hot cracking, while a variety of structural factors is decisive for hot cracking

initiation, depending on chemical composition of the cast steel. The low-carbon and low-alloyed steel castings crack due to the presence

of the type II sulphides, the cause of cracking of the high-carbon tool cast steels is the net of secondary cementite and/or ledeburite

precipitated along the boundaries of solidified grains. Also the brittle phosphor and carbide eutectics precipitated in the final stage

solidification are responsible for cracking of castings made of Hadfield steel. The examination of mechanical properties at 1050°C

revealed low or very low strength of high-carbon cast steels.

The article presents the method to assess the diffusion coefficient D in the sub-layer of intermetallic phases formed during hot-dip

galvanizing “Armco” iron and ductile cast iron EN-GJS-500-7. Hot-dip galvanizing is one of the most popular forms of long-term

protection of Fe-C alloys against corrosion. The process for producing a protective layer of sufficient quality is closely related to diffusion

of atoms of zinc and iron. The simulation consist in performed a hot-dip galvanizing in laboratory condition above Fe-C alloys, in the

Department of Engineering of Cast Alloys and Composites. Galvanizing time ranged from 15 to 300 seconds. Then metallographic

specimens were prepared, intermetallic layers were measured and diffusion coefficient (D) were calculated. It was found that the diffusion

coefficient obtained during hot-dip galvanizing “Armco” iron and zinc is about two orders of magnitude less than the coefficient obtained

on ductile cast iron EN-GJS-500-7.

Hot tearing severity was evaluated in this experiment by introducing a new apparatus called Constrained Rod Casting Modified Horizontal (CRCM-Horizontal). Six constraint bars with different lengths can produce hot tearing on the cast sample. Mold position was modified from vertical to horizontal and the shape was changed from a harp shape to a star shape, which allows for the liquid metal to feed into each rod cavity simultaneously. Hot tearing development was recorded along the bars by a digital camera. A new Hot Tearing Susceptibility (HTS) formula was developed for quantitative investigation of hot tearing on a cast sample. The parameters of the HTS formula are bar length of cast sample (Li), tear severity (Ci) and location of hot tear (Pi). Footprint charts and hot tear scales are used to illustrate hot tearing severity. The experiment was conducted with Al-1.36Zn-1.19Si and Al-5.9Cu-1.9Mg alloys to investigate the sensibility of the apparatus and modification its operation.

Nil strength temperature of 1062°C and nil ductility temperature of 1040°C were experimentally set for CuFe2 alloy. The highest formability at approx. 1020°C is unusable due to massive grain coarsening. The local minimum of ductility around the temperature 910°C is probably due to minor formation of γ-iron. In the forming temperatures interval 650-950°C and strain rate 0.1-10 s–1 the flow stress curves were obtained and after their analysis hot deformation activation energy of 380 kJ·mol–1 was achieved. Peak stress and corresponding peak strain values were mathematically described with good accuracy by equations depending on Zener-Hollomon parameter.

The main objective of the present work was to determine the effect of powder composition on microstructure and properties of iron-base materials used as matrices in diamond impregnated tools. The Fe-Cu-Ni powders premixed and ball-milled for 30 hours, were used for the experiments. The influence of manufacturing process parameters on microstructure and mechanical properties of produced sinters was investigated. Sintering was done by hot-pressing technique in graphite mould. The powders were consolidated to a virtually pore-free condition during 3 minutes hold at 35MPa and 900°C. Investigations of the sintered materials included: density, hardness, static tensile test and X-ray diffraction (XRD) analysis. Microstructural and fractographic observations were also made with a scanning electron microscope (SEM). The obtained results indicate that the sintered parts have a high density, close to the theoretical value, good plasticity, relatively high hardness and yield strength, and are characterized by a coarse-grained microstructure.

We report on the status of long-wave infrared Auger suppressed HgCdTe multilayer structures grown on GaAs substrates designed for high operating temperature condition: 200-300 K exhibiting, detectivity -10¹¹ cmHz^1/2/W, time response within a –120 ps range at 230 K. Abnormal responsivity within the range of -30 A/W for electrical area 30×30 μm² under reverse bias V = 150 mV is reported. Maximum extraction coefficient of -2.3 was estimated for analysed structures.

Hot point drills were carried through in the Hans Glacier (Spitsbergen). For that purpose a non-cored hot point drill of 700 wattage was constructed. It was used among others for installing the ablation-movement stakes, for hydrological observations and in the boreholes an ice temperature was controlled.

This paper analyses the heat treatment of the hot-dip zinc coating deposited on both cast iron and steel. The aim of research is to increase coating hardness and wear resistance without decreasing its anticorrosion properties. Hot-dip zinc coating was deposited in industrial conditions (acc. PN-EN ISO 10684) on disc shape samples and bolts M12x60. The achieved results were assessed on the basis of microscopic observation (with the use of an optical and scanning microscope), EDS (point and linear) analysis and micro-hardness measurements. It was discovered that the heat treatment of zinc coating results in an increase in hardness which is caused by the corresponding changes in microstructure.

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.

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.

In this work, T-shaped mould design was used to generate hot spot and the effect of Sr and B on the hot tearing susceptibility of A356 was investigated. The die temperature was kept at 250o C and the pouring was carried out at 740o C. The amonut of Sr and B additions were 30 and 10 ppm, respectively. One of the most important defects that may exist in cast aluminium is the presence of bifilms. Bifilms can form by the surface turbulence of liquid metal. During such an action, two unbonded surfaces of oxides fold over each other which act as a crack. Therefore, this defect cause many problems in the cast part. In this work, it was found that bifilms have significant effect over the hot tearing of A356 alloy. When the alloy solidifies directionally, the structure consists of elongated dendritic structure. In the absence of equiaxed dendrites, the growing tips of the dendrites pushed the bifilms to open up and unravel. Thus, leading to enlarged surface of oxide to become more harmful. In this case, it was found that these bifilms initiate hot tearing.

Flake graphite cast iron was hot-dip coated with pure aluminium or aluminium alloys (AlSi11 and AlTi5). The study aimed at determining

the influence of bath composition on the thickness, microstructure and phase composition of the coatings. The analysis was conducted by

means of an optical microscope and a scanning electron microscope with an EDS spectrometer. It was found that the overall thickness of a

coating was greatly dependent on the chemical composition of a bath. The coatings consisted of an outer layer and an inner intermetallic

layer, the latter with two zones and dispersed graphite. In all the cases considered, the zone in the inner intermetallic layer adjacent to the

cast iron substrate contained the Al5Fe2 phase with small amount of silicon; the interface between this phase and the cast iron substrate

differed substantially, depending on the bath composition. In the coatings produced by hot-dipping in pure aluminium the zone adjacent to

the outer layer had a composition similar to that produced from an AlTi5 bath, the Al3Fe phase was identified in this zone. The Al3Fe also

contained silicon but its amount was lower than that in the Al5Fe2. In the coatings produced by hot-dipping in AlSi11, the zone adjacent to

the outer layer contained the Al3FeSi phase. The analysis results showed that when AlSi11 alloy was applied, the growth mode of the inner

layer changed from inwards to outwards. The interface between the Al5Fe2 phase and the cast iron substrate was flat and the zone of this

phase was very thin. Locally, there were deep penetrations of the Al5FeSi phase into the outer layer, and the interface between this phase

and the outer layer was irregular. Immersion in an AlTi5 bath caused that the inner intermetallic layer was thicker than when pure

aluminium or AlSi11 alloy baths were used; also, some porosity was observed in this layer; and finally, the interface between the inner

layer and the cast iron substrate was the most irregular.

The paper addresses the macro- and microsegregation of alloying elements in the new-developed Mn-Al TRIP steels, which belong to the third generation of advanced high-strength steels (AHSS) used in the automotive industry. The segregation behaviour both in the as-cast state and after hot forging was assessed in the macro scale by OES and by EDS measurements in different structural constituents. The structural investigations were carried out using light and scanning electron microscopy. A special attention was paid to the effect of Nb microaddition on the structure and the segregation of alloying elements. The tendency of Mn and Al to macrosegregation was found. It is difficult to remove in Nb-free steels. Microsegregation of Mn and Al between austenite and ferritic structural constituents can be removed.

This article discusses results of an analysis of mechanical properties of a sintered material obtained from a mixture of elemental iron, copper and nickel powders ball milled for 60 hours. The powder consolidation was performed by hot pressing in a graphite mould. The hot pressing was carried out for 3 minutes at 900 °C and under a pressure of 35 MPa. The sintered specimens were tested for density, porosity, hardness and tensile strength. Their microstructures and fracture surfaces were also examined using a scanning electron microscope (SEM). The study was conducted in order to determine the suitability of the sintered material for the manufacture of metal-bonded diamond tools. It was important to assess the effects of chemical composition and microstructure of the sintered material on its mechanical properties, which were compared with those of conventional metal bond material produced from a hot-pressed SMS grade cobalt powder. Although the studied material shows slightly lower strength and ductility as compared with cobalt, its hardness and offset yield strength are sufficiently high to meet the criteria for less demanding applications.