INVESTIGATION OF THE DISLOCATION STRUCTURE AND LONG-RANGE INTERNAL STRESSES DEVELOPING IN AN AUSTENITIC STEEL DURING TENSILE TEST AND LOW-CYCLE FATIGUE

18/10 austenitic stainless steel samples were tensile deformed to different strain values, and fatigued with different plastic strain amplitudes up to failure. In latter case special care was taken to unload the samples either from the tensile or the compressive stress maximum of the hysteresis loop, respectively. The specimens were cut perpendicular and parallel to the load axis, and these surfaces were investigated by high resolution X-ray line profile analysis. The line profiles reveal characteristically asymmetric line broadening as compared to the undeformed initial state. From the line broadening and the asymmetry the dislocation density and the long-range internal stresses prevailing in the cell walls and in the cell interiors have been evaluated. The long-range internal stresses were interpreter! on the basis of the composite model of the dislocation cell structure. The results can be used for the different residual life prediction methods

Effect of grain boundary structure on the intercrystalline damaging of austenic steel during brazing

During brazing of austenitic stainless steel with copper based brazing material a common failure occurs, namely that the brazing material solutes along grain boundaries, which looks like cracks. This unfortunate effect occurred when AISI 304 and 310 steels are brazing. To avoid this unwanted effect - since the cracks propagate mainly on high angle grain boundaries - our goal was to enhance the number of special coincident site lattice type grain boundaries with thermomechanical treatment. Experiments were performed for 1, 48 and 72 hour heat treatments on materials cold rolled at different levels. After the thermomechanical treatment significant decrease in the crack size was found in depth and width, respectively

Detecting wage under-reporting using a double hurdle model

We estimate a double hurdle (DH) model of the Hungarian wage distribution assuming censoring at the minimum wage and wage under-reporting (i.e. compensation consisting of the minimum wage, subject to taxation, and an unreported cash supplement). We estimate the probability of under-reporting for minimum wage earners, simulate their genuine earnings and classify them and their employers as 'cheaters' and 'non-cheaters'. In the possession of the classification we check how cheaters and non-cheaters reacted to the introduction of a minimum social security contribution base, equal to 200 per cent of the minimum wage, in 2007. The findings suggest that cheaters were more likely to raise the wages of their minimum wage earners to 200 per cent of the minimum wage thereby reducing the risk of tax audit. Cheating firms also experienced faster average wage growth and slower output growth. The results suggest that the DH model is able to identify the loci of wage under-reporting with some precision

INVESTIGATION OF THE SIDE BRANCH ACCESS WITH SIMPLE VESSEL MODEL DURING BIFURCATION STENTING

Endovascular stents such as coronary stents can be used for the treatment of atherosclerosis. If the narrowing involves a main vessel and a side branch as well, physicians have to use bifurcation stenting technique. Bifurcation lesions constitute nearly 15 % of all percutaneous coronary interventions (PCI), so the investigation of bifurcation stenting methods is very important. This article introduces a simple method to measure side branch access and related functional stent properties in the case of stent-balloon technique. With this method we can tell if bifurcation stenting is possible or not, and if so the size of the available access

Magajáró fa- és tuskófeldolgozó gép vizsgálata és fejlesztése.

A VIZSGÁLAT ÉS Fejlesztés tárgyát képező gép funkciója a fakitermelés utan a földből kiforgatott gyö ¬ kértuskók ÉS fűrészipari célra tartózkodás Mellett alkalmas faanyagok helyszíni feldolgozása (aprítása). AZ aprítással a fakitermelés melléktermékeként keletkező a Nagy mennyiségben Autóüveges Autóüveges Autóüveges ÉS jelentős energiaértékkel rendelkező gyökértuskók tüzelőanyagként hasznosíthatók vagy esetleg Egyéb célokra is felhasználhatóvá válnak. A gépre épülő Technológia széleskörű elterjedésével megszüntethető a termőterületeken Tárolt, a termőterület 10-15%-a lefoglaló, Lassan (35-40 Év alatt) lebomló tuskók felhalmozása, ugyanakkor a folyamatosan keletkező, jelentős mennyiségű faanyag megújuló energiaforrásként hasznosítható. A kísérleti gép fejlesztését a fásszárú energiahor ¬ dozókkal szembeni piaci igények növekedése ÉS Minőségi elvárásai is indokolják

Investigation of Composite Behaviour of Lath Martensite

It is very important for our research that we are able to examine the orientation of packets and their relationship to directions of stress that cause plastic deformation. We use electron backscatter diffraction (EBSD) to achieve this. EBSD examination requires very careful sample preparation. In our work we have developed a sample preparation method for electron bakcscatter diffraction examination. In this study we present the method, which consists of multistage mechanical grinding, polishing and ion polishing. Optimal parameters for each steps (eg.: grinding, polishing and sputtering time, milling angle) were determined for lath martensitic steel, however, it could be used for other type of steel with minor adjustments

A léces martenzit összetett jellegének vizsgálata

Kutatásunk szempontjából nagyon fontos, hogy meg tudjuk vizsgálni a kötegek orientációját és ennek viszonyát az alakváltozást okozó feszültség irányával. Ehhez úgynevezett visszaszórtelektron-diffrakciós vizsgálatot (EBSD) alkalmazunk. Ennek a vizsgálatnak az elvégzése nagyon gondos minta-előkészítést igényel. A tanulmányban az általunk kidolgozott módszert mutatjuk be, amely többlépcsős mechanikai csiszolásból, polírozásból, valamint ionpolírozásból áll. Az egyes lépések optimális paramétereit (pl: mechanikai csiszolás, polírozás, ionpolírozás ideje, minta ionpolírozás közbeni dőlésszöge) a léces martenzites szövetszerkezetű acél mintákra határoztuk meg, amelyek kis módosításokkal más szövetszerkezetű acél próbatesteknél is alkalmazhatóak

Coefficients of association between nominal and fully ranked ordinal variables with applications to ecological network analysis

A central issue of ecological data analysis is the pairwise comparison of variables describing biological entities and the environment. Difficulties arise with calculations if the measurement scales of the variables differ. In particular, no method is available for measuring the association between a nominal and a fully ranked ordinal variable. Here two coefficients are suggested by reducing this problem to the evaluation of pattern in string representations. The first one is a topological measure that counts the number of other types of elements occurring between pairs of elements of a given state along the entire length of the string, thus providing a global coefficient of aggregation/segregation. The second coefficient is based on counting the number of different elements within substrings generated from the complete string with the moving window technique. Thus, it is a local measure. There is no compact and general formula for calculating these measures, and heuristics are involved for finding the possible minimum and maximum values by algorithmic approximation and Markov Chain Monte Carlo simulation. An R function is provided for computations. The methods are applied to the comparison of nominal variables (biological traits) categorizing marine food web nodes with fully ranked variables describing major graph theory properties of the same nodes in the network. The most descriptive traits (mobility, major functional group) significantly associated with network metrics (weighted indices) were identified from a variety of combinations across three marine ecosystems. These coefficients thus provide an objective, statistically-sound method for identifying ecologically meaningful traits