A study of mechanical properties of high manganese steels after different rolling conditions

In the paper, two grades of high-manganese steels with aluminum after a thermos - mechanical treatment were studied. Steel grades with an austenitic - ferritic structure with various contents of carbon, manganese and aluminum were selected for the studies. The main goal of the work was to define the most preferable parameters of heat treatment, rolling finish temperature and cooling rate in order to obtain the most favorable strength - ductility relation for the examined steels. The structural analysis was carried out using optical microscopy techniques. The evaluation of strength properties was carried out based on the results of static tensile test of steel sheets

Vacancy formation in Fe-Al of B2 and DO3 alloys

The positron lifetime spectroscopy is employed to study vacancy formation in intermetallic phases of DO3 and B2 structures from Fe-Al system as a function of Al concentration, ternary additive (Cr) and their thermal treatment. Lifetime spectra were fitted en block by a simple trapping model encoded directly to the software (computer program LT-9). In the investigated range of Al concentration (28, 38, 42, and 45 at%) only two types of defects are found. In DO3 region a single type of defects (characterized by positron lifetime ¿1 = 170 § 2 ps) is detected and indicated as vacancies in the Fe sublattice (VFe). In B2 region a small amount of an additional type of defects (characterized by positron lifetime ¿2 = 214 § 13 ps) appears. Supposedly, these are vacancies in Al sublattice (VAl). For Fe28Al and Fe28Al5Cr samples changes in VFe concentration are determined as a function of the sample composition, annealing time at 1000±C and quenching the samples to air and oil. The defect concentration increases with increase in Al content. For FeAl with Al above 38 at%, the total concentration of defects is so high that positrons are exclusively trapped by defects. Therefore the concentrations VAl and VFe cannot be determined separately. However, the ratio of VAl concentration to VFe concentration is estimated as a function of Al content

Study of the structure of intermetalics from Fe - Al system after the hot rolling

This paper presents the results of structure analysis of Fe - Al alloys after hot rolling deformation. Microstructure analysis were performed before and after deformation using a scanning transmission electron microscopy (STEM) technique. The detailed quantities research of the structures was conducted using scanning electron microscopy (SEM) equipped with the gun with cold field emission and the detector of electron back scattering diffraction (EBSD)

Analysis of material reliability of AlSi17Cu5 alloy using statistical weibull distribution

Analysis of reliability of AlSi17Cu5 alloy was carried out using the so-called „permanence measure”. Two-parameter Weibull distribution, defining stability of material features, is its numerical equivalent. Mechanical properties (HB hardness HB, tensile strength Rm, and yield strength R0,2) were selected as parameters for statistical evaluation, whereas inoculation with phosphorus (CuP10) and overheating to 920 oC (separately and jointly) together with intense cooling of the alloy were the factors shaping the influence of technology type. Statistical calculations, preceded by verification of hypotheses on conformity of distribution of the investigated resultant characteristics with normal distribution, were supported with variance estimators, and correlation and regression analyses

The effect of strain rate on the impact strength of the high-Mn steel

In the paper, results of impact bending tests of a high-manganese steel of Fe – 30 wt.%, Mn – 9 wt.%, Al – 0,65 wt.%, C grade are presented. The tests were carried out using a flywheel machine, suitable for dynamic stretching and impact bending tests in the range of linear velocity of the forcing element from 5 ÷ 40 m/s. The obtained test results were compared with the results of impact resistance of the studied steel determined using Charpy machine. Structural investigations were carried out using scanning transmission electron microscopy. Surfaces of fractures formed in the break point during bending tests were analyzed, and they indicate a presence of mixed transcrystalline fractures with a predominance of plastic fractures

When genome-based approach meets the “Old but Good”: revealing genes involved in the antibacterial activity of Pseudomonas sp. P482 against soft rot pathogens

Dickeya solani and Pectobacterium carotovorum subsp. brasiliense are recently established species of bacterial plant pathogens causing black leg and soft rot of many vegetables and ornamental plants. Pseudomonas sp. strain P482 inhibits the growth of these pathogens, a desired trait considering the limited measures to combat these diseases. In this study, we determined the genetic background of the antibacterial activity of P482, and established the phylogenetic position of this strain. Pseudomonas sp. P482 was classified as Pseudomonas donghuensis. Genome mining revealed that the P482 genome does not contain genes determining the synthesis of known antimicrobials. However, the ClusterFinder algorithm, designed to detect atypical or novel classes of secondary metabolite gene clusters, predicted 18 such clusters in the genome. Screening of a Tn5 mutant library yielded an antimicrobial negative transposon mutant. The transposon insertion was located in a gene encoding an HpcH/HpaI aldolase/citrate lyase family protein. This gene is located in a hypothetical cluster predicted by the ClusterFinder, together with the downstream homologs of four nfs genes, that confer production of a non-fluorescent siderophore by P. donghuensis HYS(T). Site-directed inactivation of the HpcH/HpaI aldolase gene, the adjacent short chain dehydrogenase gene, as well as a homolog of an essential nfs cluster gene, all abolished the antimicrobial activity of the P482, suggesting their involvement in a common biosynthesis pathway. However, none of the mutants showed a decreased siderophore yield, neither was the antimicrobial activity of the wild type P482 compromised by high iron bioavailability. A genomic region comprising the nfs cluster and three upstream genes is involved in the antibacterial activity of P. donghuensis P482 against D. solani and P. carotovorum subsp. brasiliense. The genes studied are unique to the two known P. donghuensis strains. This study illustrates that mining of microbial genomes is a powerful approach for predictingthe presence of novel secondary-metabolite encoding genes especially when coupled with transposon mutagenesis

Application of third generation synchrotron source to studies of noncrystalline materials : In-Se amorphous films

The local structure of vacuum evaporated In-Se amorphous films, containing 50, 60, and 66 at .% Se, was studied using differential anomalous X -ray scattering and extended X -ray absorption fine structure. Both intensity and absorption spectra were measured in the vicinity of the absorption K -edge of Se. The differential anomalous X -ray scattering data were converted to real space by the inverse Fourier transform yielding the differential radial distribution functions. The obtained results provide evidence for the presence of Se-In spatial correlations for In5 0 Se50 and Se-In and Se-Se correlations for In40 Se60 and In34 Se66 within the first coordination sphere

Thirty years of vegetation dynamics in the Rospuda fen (NE Poland)

Little is known about the vegetation dynamics of fens, and especially of hydrologically undisturbed examples. We described the vegetation of an undisturbed mesotrophic rich fen (percolation mire) in 2006–2008 and 2016 and compared our results with vegetation records from the 1980s to identify any longer-term changes. Eight vegetation types were distinguished. On the whole, the vegetation of the mire has remained very stable throughout the last 30 years. However, detailed comparisons of permanent plots recorded twice in the last ten years indicated an expansion of shrubs in patches of Sphagnum - small sedge vegetation. There were also several less prominent changes in the abundance of particular species in other mire vegetation types: (1) an increase of sedges, reeds and Calliergonella cuspidata at the expense of rich-fen moss species in communities of brown moss - small sedge; (2) a change in composition of the moss layer in pine - birch fen woodland; (3) an increase of reedbed species and reduced Alnus glutinosa abundance in flooded riparian alder woodland; and (4) a decline of wetland herbs and mosses in alder spring fen woodland at the edges of the valley

Comparison of Cu-Mg-Al-Ox and Cu/Al2O3 in selective catalytic oxidation of ammonia (NH3-SCO)

Copper-based materials are promising catalysts in the selective catalytic oxidation of ammonia into nitrogen and water vapour (NH 3 -SCO). Investigations under applied reaction conditions over such materials seem to be rare and a comprehensive understanding of the involved active copper oxide species could facilitate a knowledge-based catalyst optimization. In the present work, Cu-Mg-Al-O x mixed metal oxides and Cu/Al 2 O 3 active catalysts in NH 3 -SCO were investigated under NH 3 /O 2 /CO 2 /H 2 O/N 2 reaction conditions. Powder XRD, BET, NH 3 -TPD, H 2 -TPR and XAFS methods were used to characterize Cu-Mg-Al-O x (Cu/Mg/Al = 8/63/29, mol%) and 10 wt% Cu/Al 2 O 3 . Cu-Mg-Al-O x hydrotalcite derived mixed metal oxides were obtained by coprecipitation, while Cu/Al 2 O 3 was prepared by incipient wetness impregnation. A highly dispersed copper oxide species formed on Cu-Mg-Al-O x , while a mixture of highly dispersed (CuO x ) and bulk copper oxide species (CuO and CuAl 2 O 4 ) formed on Cu/Al 2 O 3 . The comparison of Cu-Mg-Al-O x and Cu/Al 2 O 3 in NH 3 -SCO provided good insight into the nature of the active species present in both copper-based catalysts. It was found that highly dispersed easily reducible copper oxide species and bulk copper oxide species appear as active species under NH 3 /O 2 /N 2 and NH 3 /O 2 /CO 2 /H 2 O/N 2 reaction conditions, respectively