The paper presents the effect of manganese on the crystallization process, microstructure and selected properties: cast iron hardness as well as ferrite and pearlite microhardness. The compacted graphite was obtained by Inmold technology. The lack of significant effect on the temperature of the eutectic transformation was demonstrated. On the other hand, a significant reduction in the eutectoid transformation temperature with increasing manganese concentration has been shown. The effect of manganese on microstructure of cast iron with compacted graphite considering casting wall thickness was investigated and described. The nomograms describing the microstructure of compacted graphite iron versus manganese concentration were developed. The effect of manganese on the hardness of cast iron and microhardness of ferrite and pearlite were given.
In this paper is discussed the effect of the inoculant mischmetal addition on the microstructure of the magnesium alloy AZ91. The concentration of the inoculant was increased in the samples within the range from 0.1% up to 0.6%. The thermal process was performed with the use of Derivative and Thermal Analysis (DTA). A particular attention was paid to finding the optimal amount of the inoculant, which causes fragmentation of the microstructure. The concentration of each element was verified with use of a spark spectrometer. In addition, the microstructures of every samples were examined with the use of an optical microscope and also was performed an image analysis with a statistical analysis using the NIS–Elements program. The point of those analyses was to examine the differences in the grain diameters of phase αMg and eutectic αMg+γ(Mg17Al12) in the prepared samples as well as the average size of each type of grain by way of measuring their perimeters. This paper is the second part of the introduction into a bigger research on grain refinement of magnesium alloys, especially AZ91. Another purpose of this research is to achieve better microstructure fragmentation of magnesium alloys without the relevant changes of the chemical composition, which should improve the mechanical properties.
The objective of this study was to investigate combustion characteristics of biomass (willow, Salix viminalis) burnt in air and O2/CO2mixtures in a circulating fluidized bed (CFB). Air and oxy-combustion characteristics of wooden biomass in CFB were supplemented by the thermogravimetric and differential thermal analyses (TGA/DTA). The results of conducted CFB and TGA tests show that the composition of the oxidizing atmosphere strongly influences the combustion process of biomass fuels. Replacing N2in the combustion environment by CO2caused slight delay (higher ignition temperature and lower maximum mass loss rate) in the combustion of wooden biomass. The combustion process in O2/CO2mixtures at 30% and 40% O2is faster and shorter than that at lower O2concentrations.
This article contains information concerning of the analysis the possibility of defining refinery qualities of the slag based thermophysical and thermodynamical data. The paper presents a model of slag refining processes and a method of determining the reduction capability of slag solutions. Slag was analysed with the use of the DTA methods for the brass melting conductions. The study of computer program including the satisfactory number of data there are used in to the design a modern device rotating head used for gas-slag refining. It was achieved that the refining gas and fluxes were distributed ever by the rotating head. High effectiveness of the gas-slag refining processes was proved for the brass.
This work presents the results of the research of the effect of the inoculant Emgesal Flux 5 on the microstructure of the magnesium alloy AZ91. The concentration of the inoculant was increased in samples in the range from 0.1% to 0.6%. The thermal processes were examined with the use of Derivative and Thermal Analysis (DTA). During the examination, the DTA samplers were preheated up to 180 °C. A particular attention was paid to finding the optimum amount of inoculant, which would cause fragmentation of the microstructure. The concentration of each element was verified by means of a spark spectrometer. In addition, the microstructures of the samples were examined with the use of an optical microscope, and an image analysis with a statistical analysis using the NIS–Elements program were carried out. Those analyses aimed at examining the differences between the grain diameters of phase αMg and eutectic αMg+γ(Mg17Al12) in the prepared samples as well as the average size of each type of grain by way of measuring their perimeters. This paper is an introduction to a further research of grain refinement in magnesium alloys, especially AZ91. Another purpose of this research is to achieve better microstructure fragmentation of magnesium alloys without the related changes of the chemical composition, which should improve the mechanical properties.
This paper shows how it is possible to obtain an ausferrite in compacted graphite iron (CGI) without heat treatment of castings. Vermicular graphite in cast iron was obtained using Inmold technology. Molybdenum was used as alloying additive at a concentration from 1.6 to 1.7% and copper at a concentration from 1 to 3%. It was shown that ausferrite could be obtained in CGI through the addition of molybdenum and copper in castings with a wall thickness of 3, 6, 12 and 24 mm. Thereby the expensive heat treatment of castings was eliminated. The investigation focuses on the influence of copper on the crystallization temperature of the graphite eutectic mixture in cast iron with the compacted graphite. It has been shown that copper increases the eutectic crystallization temperature in CGI. It presents how this element influences ausferrite microhardness as well as the hardness of the tested iron alloy. It has been shown that above-mentioned properties increases with increasing the copper concentration.
The paper presents the results of the research on the effect of copper on the crystallization process, microstructure and selected properties
of the compacted graphite iron. Compacted graphite in cast iron was obtained using Inmold process. The study involved the cast iron
containing copper at a concentration up to approximately 4%. The effect of copper on the temperature of the eutectic crystallization as well
as the temperature of start and finish of the austenite transformation was given. It has been shown that copper increases the maximum
temperature of the eutectic transformation approximately by 5C per 1% Cu, and the temperature of the this transformation finish
approximately by 8C per 1% Cu. This element decreases the temperature of the austenite transformation start approximately by 5C per
1% Cu, and the finish of this transformation approximately by 6C per 1% Cu. It was found that in the microstructure of the compacted
graphite iron containing about 3.8% Cu, there are still ferrite precipitations near the compacted graphite. The effect of copper on the
hardness of cast iron and the pearlite microhardness was given. This stems from the high propensity to direct ferritization of this type of
cast iron. It has been shown copper increases the hardness of compacted graphite iron both due to its pearlite forming action as well as
because of the increase in the pearlite microhardness (up to approx. 3% Cu). The conducted studies have shown copper increases the
hardness of the compacted graphite iron approximately by 35 HB per 1% Cu.
This paper presents the problems related to smelting gray and ductile cast iron. Special attention is paid to the metallurgical quality of cast iron. It depends on the type of furnace, charge materials and the special combination of charge, overheating and holding temperature, melting time, modification and spheroidization method. The evaluation of metallurgical quality has been performed by using derivativethermal analysis (DTA). During the smelting process and secondary metallurgy, the ITACA system was used allowing to obtain information on alloy characteristic temperatures (Tliquidus, TeMin, TeMax, Tsolidus), VPS value, recalescence value, IGQ coefficient, nucleation gauge, porosity etc. The results of investigations and calculations are displayed in the form of graphs and dependencies. It has been shown that the derivative-thermal analysis (DTA) is an effective complement of chemical analysis and it has been found that both the increase in temperature and metal holding time have a negative impact on the metallurgical quality of liquid metal. The metallurgical quality can be improved by using proper composition of charge materials and modifiers.
High-alloy corrosion-resistant ferritic-austenitic steels and cast steels are a group of high potential construction materials. This is
evidenced by the development of new alloys both low alloys grades such as the ASTM 2101 series or high alloy like super or hyper duplex
series 2507 or 2707 [1-5]. The potential of these materials is also presented by the increasing frequency of sintered components made both
from duplex steel powders as well as mixtures of austenitic and ferritic steels [6, 7]. This article is a continuation of the problems presented
in earlier works [5, 8, 9] and its inspiration were technological observed problems related to the production of duplex cast steel.
The analyzed AISI A3 type cast steel is widely used in both wet exhaust gas desulphurisation systems in coal fired power plants as well as
in aggressive working environments. Technological problems such as hot cracking presented in works [5, 8], with are effects of the rich
chemical composition and phenomena occurring during crystallization, must be known to the technologists.
The presented in this work phenomena which occur during the crystallization and cooling of ferritic-austenitic cast steel were investigated
using numerical methods with use of the ThermoCalc and FactSage® software, as well with use of experimental thermal-derivative
analysis.
This paper presents the results of hypoeutectic 226 grade alloy as well as prepared on its basis Al-Si alloy containing Cr, V and Mo. The
additives tested were added as AlCr15, AlV10 and AlMo8 master alloys. Alloys tested were poured into DTA sampler as well as using
pressure die casting. An amount of Cr, V and Mo additives in alloy poured into DTA sampler comprised within the range approximately
0.05-0.35%. Alloys to pressure die casting contained 0.05-0.20% Cr, V and Mo. The crystallization process was examined using the derivative
thermal analysis (DTA). The microstructure of castings made in the DTA sampler as well as castings made with use of pressure die
casting were examined. The basic mechanical properties of castings made using pressure die casting were defined too. It has been shown
in the DTA curves of Al-Si alloy containing approximately 0.30 and 0.35% Cr, Mo, and V there is an additional thermal effect probably
caused by a peritectic crystallization of intermetallic phases containing the aforementioned additives. These phases have a morphology
similar to the walled and a relatively large size. The analogous phases also occur in pressure die casting alloys containing 0.10% or more
additions of Cr, V and Mo. The appearance of these phases in pressure die casting Al-Si alloys coincides with a decrease in the value of
the tensile strength Rm and the elongation A. It has been shown die castings made of Al-Si alloys containing the aforementioned additives
have a higher Rm and A than 226 alloy.
en
pl
