Heating of steel or structural aluminum alloys at a speed of 2 to 50 K/min – characterizing the fire conditions – leads to a reduction in mechanical properties of the analyzed alloys. The limit of proportionality fp, real fy and proof f₀₂ yield limit, breaking strength fu and longitudinal limit of elasticity E decrease as the temperature increases. Quantitative evaluation of the thermal conversion in strengths of structural alloys is published in Eurocodes 3 and 9, in the form of dimensionless graphs depicting reduction coefficients and selected (tabulated) discrete values of mechanical properties. The author’s proposal for an analytical formulation of code curves describing thermal reduction of elasticity modulus and strengths of structural alloys recommended for an application in building structures is presented in this paper.

The work presents results of the investigations of effect of intensive cooling of alloy AC-AlSi7Mg with alloy additions on microstructure and mechanical properties of the obtained casts. The experimental casts were made in ceramic molds preliminarily heated to 180°C, into which AC-AlSi7Mg with alloy additions was poured. Within implementation of the research, a comparison was made of the microstructure and mechanical properties of the casts obtained in ceramic molds cooled at ambient temperature and the ones intensively cooled in a cooling liquid. Kinetics and dynamics thermal effects recorded by the TDA method were compared. Metallographic tests were performed with the use of optical microscope and strength properties of the obtained casts were examined: UTS, Elongation and HB hardness.

The present study, aims to investigate the effect of minor Zr and Nb alloying on soft magnetic and electrical properties of Fe86(ZrxNb1-x)7B6Cu1 (x = 1, 0.75, 0.5, 0.25) alloys. The investigated alloys were prepared through the melt spinning process. Within the examined compositional range (Nb up to 5.25at%, respectively), the soft magnetic properties and electrical resistivity of the alloys continuously increase with increasing Nb content. However increasing the Nb content further decreases such properties. We could confirm the influence of ratio of Zr and Nb on grain growth and crystallization fraction during crystallization by using the soft magnetic properties and electrical properties.

In this study, modification of the AZ91 magnesium alloy surface layer with a CO2 continuous wave operation laser has been taken on. The

extent and character of structural changes generated in the surface layer of the material was being assessed on the basis of both macro- and

microscopy investigations, and the EDX analysis. Considerable changes in the structure of the AZ91 alloy surface layer and the

morphology of phases have been found. The remelting processing was accompanied by a strong refinement of the structure and a more

uniform distribution of individual phases. The conducted investigations showed that the remelting zone dimensions are a result of the

process parameters, and that they can be controlled by an appropriate combination of basic remelting parameters, i.e. the laser power, the

distance from the sample surface, and the scanning rate. The investigations and the obtained results revealed the possibility of an effective

modification of the AZ91 magnesium alloy surface layer in the process of remelting carried out with a CO2 laser beam.

The main scope of the article is the development of a computer system, which should give advices at problem of cooper alloys

manufacturing. This problem relates with choosing of an appropriate type of bronze (e.g. the BA 1044 bronze) with possible modification

(e.g. calcium carbide modifications: Ca + C or CaC2) and possible heat treatment operations (quenching, tempering) in order to obtain

desired mechanical properties of manufactured material described by tensile strength - Rm, yield strength - Rp0.2 and elongation - A5. By

construction of the computer system being the goal of presented here work Case-based Reasoning is proposed to be used. Case-based

Reasoning is the methodology within Artificial Intelligence techniques, which enables solving new problems basing on experiences that

are solutions obtained in the past. Case-based Reasoning also enables incremental learning, because every new experience is retained each

time in order to be available for future processes of problem solving. Proposed by the developed system solution can be used by

a technologist as a rough solution for cooper alloys manufacturing problem, which requires further tests in order to confirm it correctness.

Submitted work deals with the analysis of reoxidation processes for aluminium alloys. Due to the aluminium high affinity to the oxygen, the oxidation and consequently reoxidation will occur. Paper focuses on the gating system design in order to suppress and minimize reoxidation processes. Design of the gating system is considered as one of the most important aspect, which can reduce the presence of reoxidation products - bifilms. The main reason for the reoxidation occurrence is turbulence during filling of the mold. By correctly designing the individual parts of gating system, it is possible to minimize turbulence and to ensure a smooth process of the mold filling. The aim of the work is an innovative approach in the construction of gating system by using unconventional elements, such as a naturally pressurized system or vortex elements. The aim is also to clarify the phenomenon during the gating system filling by visualization with the aid of ProCAST numerical simulation software. ProCAST can calculate different indicators which allow to better quantify the filling pattern.

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.

The paper deals with the impact of technological parameters on the heat transfer coefficient and microstructure in AlSi12 alloy using

squeeze casting technology. The casting with crystallization under pressure was used, specifically direct squeeze casting method. The goal

was to affect crystallization by pressure with a value 100 and 150 MPa. The pressure applied to the melt causes a significant increase of

the coefficient of heat transfer between the melt and the mold. There is an increase in heat flow by approximately 50% and the heat

transfer coefficient of up to 100-fold, depending on the casting conditions. The change in cooling rate influences the morphology of the

silicon particles and intermetallic phases. A change of excluded needles to a rod-shaped geometry with significantly shorter length occurs

when used gravity casting method. By using the pressure of 150 MPa during the crystallization process, in the structure can be observed an

irregular silica particles, but the size does not exceed 25 microns.

The paper presents the results of simulation of alloy layer formation process on the model casting. The first aim of this study was to

determine the influence of the location of the heat center on alloy layer’s thickness with the use of computer simulation. The second aim of

this study was to predict the thickness of the layer. For changes of technological parameters, the distribution of temperature in the model

casting and temperature changes in the characteristic points of the casting were found for established changes of technological

parameters. Numerical calculations were performed using programs NovaFlow&Solid. The process of obtaining the alloy layer with good

quality and proper thickness depends on: pouring temperature, time of premould hold at the temperature above 1300o

C. The obtained

results of simulation were loaded to authorial program Preforma 1.1 in order to determine the predicted thickness of the alloy casting

The results of studies presented in this article are an example of the research activity of the authors related to lead-free alloys. The studies covered binary SnZn90 and SnZn95 lead-free alloys, including their microstructure and complex mechanical characteristics. The microstructure was examined by both light microscopy (LM) and scanning electron microscopy (SEM). The identification of alloy chemical composition in micro-areas was performed by SEM/EDS method. As regards light microscopy, the assessment was of both qualitative and quantitative character. The determination of the geometrical parameters of microstructure was based on an original combinatorial method using phase quantum theory. Comprehensive characterization of mechanical behavior with a focus on fatigue life of alloys was performed by means of the original modified low cycle fatigue method (MLCF) adapted to the actually available test machine. The article discusses the fatigue life of binary SnZn90 and SnZn95 alloys in terms of their microstructure. Additionally, the benefits resulting from the use of the combinatorial method in microstructure examinations and MLCF test in the quick estimation of several mechanical parameters have been underlined.

The main reason of a cavitational destruction is the mechanical action of cavitation pulses onto the material’s surface. The course

of cavitation destruction process is very complex and depends on the physicochemical and structural features of a material. A resistance

to cavitation destruction of the material increases with the increase of its mechanical strength, fatigue resistance as well as hardness.

Nevertheless, the effect of structural features on the material’s cavitational resistance has been not fully clarified. In the present paper,

the cavitation destruction of ZnAl4 as cast alloy was investigated on three laboratory stands: vibration, jet-impact and flow stands.

The destruction mechanism of ZnAl4 as cast alloy subjected to cavitational erosion using various laboratory stands is shown in the present

paper.

This work presents an influence of cooling rate on crystallization process, structure and mechanical properties of MCMgAl12Zn1 cast magnesium alloy. The experiments were performed using the novel Universal Metallurgical Simulator and Analyzer Platform. The apparatus enabled recording the temperature during refrigerate magnesium alloy with three different cooling rates, i.e. 0.6, 1.2 and 2.4°C/s and calculate a first derivative. Based on first derivative results, nucleation temperature, beginning of nucleation of eutectic and solidus temperature were described. It was fund that the formation temperatures of various thermal parameters, mechanical properties (hardness and ultimate compressive strength) and grain size are shifting with an increasing cooling rate.

The results of structure and mechanical properties investigations of tungsten heavy alloy (THA) after cyclic sintering are presented. The

material for study was prepared using liquid phase sintering of mixed and compacted powders in hydrogen atmosphere. The specimens in

shape of rods were subjected to different number of sintering cycles according to the heating schemes given in the main part of the paper

From the specimens the samples for mechanical testing and structure investigations were prepared. It follows from the results of the

mechanical studies, that increasing of sintering cycles lead to decrease of tensile strength and elongation of THA with either small or no

influence on yield strength. In opposite to that, the microstructure observations showed that the size of tungsten grain increases with

number of sintering cycles. Moreover, scanning electron microscope (SEM) observations revealed distinctly more trans-granular cleavage

mode of fracture in specimens subjected to large number of sintering cycles compared with that after one or two cycles only.

The paper presents experimental results of creep and low cycle fatigue (LCF) tests carried out on the as-received cast aluminium alloys with different chemical composition and porosity. The test programmes contain creep investigations under step-increased stresses at different temperatures, and cyclic plasticity under different strain amplitudes and temperatures.

Titanium alloy (Ti-6Al-4V) has been extensively used in aircraft turbine-engine components, aircraft structural components, aerospace fasteners, high performance automotive parts, marine applications, medical devices and sports equipment. However, wide-spread use of this alloy has limits because of difficulty to machine it. One of the major difficulties found during machining is development of poor quality of surface in the form of higher surface roughness. The present investigation has been concentrated on studying the effects of cutting parameters of cutting speed, feed rate and depth of cut on surface roughness of the product during turning of titanium alloy. Box-Behnken experimental design was used to collect data for surface roughness. ANOVA was used to determine the significance of the cutting parameters. The model equation is also formulated to predict surface roughness. Optimal values of cutting parameters were determined through response surface methodology. A 100% desirability level in the turning process for economy was indicated by the optimized model. Also, the predicted values that were obtained through regression equation were found to be in close agreement to the experimental values.