A destructive pressure test of styrene-acrylonitrile (SAN) water-filter housings showed the influence of the shape and specific details of the housings on their critical areas and their destructive ...pressure. The destructive pressure varies by as much as 37 bar due to different dominant stresses in the individual types of housings. In critical areas of the housings, geometrical stress concentrators generally exist. For this reason, the stress caused by the internal pressure is locally 2.75-3.4 times greater than that expected based on the water pressure, which means that cracks are initiated in these places. However, the bottom of the housings can be in a form such that the maximum stress and the crack originates in its central part without the influence of local stress concentrators. The tensile strength of the SAN is theoretically estimated at 73 N/mm
, which is comparable with the literature data. The fracture toughness of the SAN is typically low, theoretically estimated in the range 1.45-3.55 MPa·m
, and strongly depends on the degree of the wall's stress-increasing rate or the crack-propagation rate. Therefore, at various crack-propagation rates, the critical crack depths are also different, in the range 100-600 μm. Due to this, the critical thickness for brittle fracture in the SAN is also different; it is ten times greater than the critical crack length. The characteristic of a sub-critical crack, i.e., the mirror zone, is its macroscopically smooth surface, which is microscopically very finely roughened. In the case of a sufficiently slowly growing sub-critical crack, the surface of the mirror zone contains characteristic parabolic markings. The over-critical, sufficiently rapidly growing cracks generally grow mainly in the plane-strain state and only the final thin layer of the remaining wall thickness breaks in the plane-stress state. The over-critical, sufficiently slowly growing cracks grow in the plane-stress state with a strong shear plastic tearing.
Fatigue cracks were initiated during the operation of a water-filter housing made from styrene-acrylonitrile (SAN). Using a destructive pressure test, it was confirmed that the sharp transition ...between the wall and the vertical external ribs of the filter housing at the point of the increased external diameter is the critical area of the water-filter housing. This is a consequence of the stress concentration due to the combined action of the sharp edges of the vertical external ribs and the increased stiffness due to the thicker wall and the mounting of the upper part of the housing onto the filter head. During the destructive pressure tests a crack was initiated on the external surface in the same place and spread in the same direction as the fatigue crack during the operation of the water filter. At the critical point the actual loads due to the stress concentrator are approximately 3.2 times higher than that expected based on the water pressure in the pipeline. The tensile strength of the styrene-acrylonitrile from the water-filter housing was comparable with the literature data. The fracture toughness of styrene-acrylonitrile is low and comparable to the fracture toughness of polymethylmethacrylate. The critical crack depth for the occurrence of an uncontrolled rupture for a continuously increasing load is approximately 100μm, while the plane-strain condition occurs at a thickness of about 1mm. A rapidly growing crack in the wall tends to grow in a layer of plane-strain conditions, and from the internal- to the external-wall surface. The possibility of determining the fracture toughness with a destructive pressure test of the housing or a pressure vessel with an external surface stress concentrator was achieved.
•The crack initiated in the high stress concentrator area•The critical crack depth of an uncontrolled rupture is approximately 100μm•The plane strain condition in SAN occurs at the wall thickness of approximately 1mm•The fracture toughness of SAN is low and is estimated to be 1,1-1,6MPam1/2
Article is a reflection upon f. Hugolin Sattner’s cantata “Ode to Soča”, which was created in the time of First World War and great battles of Isonzo. It outlines composer’s ideological, political ...and aesthetic outlook as a basis for his creativity thus applying methods of history of mentalities.
•Autogenous laser welding produces concave end-crater in 17–4 PH that is prone to solidification cracking.•Solidification cracking at weld end-crater causes weld leakage.•The use of novel zigzag ...laser power ramp-down profile produces significantly shorter, discontinuous, and leakage free cracks.
An analysis presents a weld leakage problems of automotive pressure sensor, caused by weld crater cracking. A two-beam laser welding (TBLW) was used to weld a circumferential weld, which undesirably increases the probability of weld leakage by creating two weld end craters on a single weld. Microstructural analysis showed that microsegregation of alloying elements combined with imposed strains causes solidification cracking at the weld end crater. A novel “zigzag” laser power ramp-down was used and the results showed a limited crack propagation by producing significantly shorter discontinuous cracks. In such weld crater endings the leakage is no longer an issue.
At the publication of a new scientific monograph on the activities of the Glasbena matica music society in Ljubljana up to 1945, an inattentive observer of Slovenian musical-historical literature ...might wonder: why another scientific work on this topic? The central national, Slovenian-declared music society has to this day been the subject of numerous observations. Many of them have touched on specific segments of its diverse activities, while others have focused solely on narrower periods that are most characteristic of its historical role.
This paper discusses directed energy deposition of 15-5 PH, which was successfully tailored with precipitation hardening (PH) to achieve the desired properties. Parametric analysis of solution ...annealing and aging at various time and temperature combinations was performed. Material characterisation was done in the as-deposited, solution annealed, and PH states. Investigations included microscopy, SEM/EDS, fractography, hardness, tensile, and impact toughness test. The as-deposited microstructure was composed of martensite laths along with delta ferrite. Optimisation of solution annealing was mandatory to achieve homogeneous austenite, which allowed PH. PH resulted in similar properties compared to conventionally produced steel. Peak aging resulted in 450 HV10 and an Rm of 1350 MPa, while the over-aged condition resulted in an impact toughness of over 77 J/cm
2
.
The tool used in die casting or hot forming is subjected to thermal and mechanical stress, resulting in damage and cracking due to thermal fatigue and melt flow. This reduces the profitability and ...efficiency of production, as the products may not meet the required dimensions and mechanical properties. Understanding the interaction between tool steel and molten aluminium alloy is critical to extending tool life. AlCrN protective coatings on tool surfaces can improve corrosion resistance, thermal fatigue and wear resistance.
The present work was carried out to predict the effect of the AlCrN protective coating on the interaction kinetics between H11 tool steel and molten aluminium alloy Al99.7. The AlCrN protective coating on the H11 tool steel sample served its purpose and slowed down the interaction between the aluminium melt from Al99.7 and the H11 tool steel, as the DSC curve of the sample that had the AlCrN protective coating applied flattened out faster, indicating the cessation of dissolution in the material at all investigated temperatures. Measurements of the thicknesses of the interaction layers also confirmed these results, whereas the thickness of the composite layer was almost the same at both experimental temperatures, 670°C and 700°C, respectively, without an AlCrN protective coating; the temperature has no effect on this layer and the types of interaction layers did not differ from each other.
Anodic and spontaneous corrosion of different types of stainless steel (AISI 304L, AISI 316L and 2205 DSS) in phosphate-buffered saline solution (PBS, pH = 7.4) at 37 °C (i.e., in simulated ...physiological solution in the human body) were examined using open circuit potential measurements, linear and cyclic polarization, and electrochemical impedance spectroscopy methods. After the anodic and spontaneous corrosion, the surface of the tested samples was investigated by light and scanning electron microscopy (SEM) with EDS analysis. It has been established that the tendency of the examined steel materials towards local corrosion decreases in the order: AISI 304L < AISI 316L < 2205 DSS. Namely, the possibility of repassivation and the resistance to local corrosion increases in the same order. The corrosion resistance of steel samples at open circuit potential is a consequence of forming a natural oxide film with a bi-layer structure and consists of an inner barrier and an outer porous film. The inner barrier film has a small thickness and extremely high resistance, while the outer porous film is much thicker but also has significantly lower resistance. The inner barrier layer mainly prevents corrosion of examined steel samples in order: AISI 304L < AISI 316L < 2205 DSS. Light microscopy and SEM/EDS analysis after pitting and spontaneous corrosion showed damage on the AISI 304L and AISI 316L surface, while the surface of 2205 DSS was almost undamaged by corrosion.
Alloying with Mn can significantly influence the magnetic behavior of soft-magnetic silicon steel. Therefore, the formation of high-temperature oxides on an Fe-Si-Al alloy for electrical steel with ...the addition of 1 wt.% Mn is investigated in this study. X-ray diffraction spectra of a high-manganese Fe-Si-Al alloy were measured at a series of increasing temperatures (from room temperature to 1200°C). Two main phases were identified (apart from Fe): cubic Fe
3
O
4
and rhombohedral Fe
2
O
3
. With a temperature increase, their ratio changes, as observed from the diffraction-peak intensities. In spite of the complex chemistry of the initial material, no further phases were identified below 750°C. At higher temperatures, several new diffraction peaks were observed. Their possible attribution is discussed. The experimental part was supplemented by surface-sensitive x-ray photoelectron spectroscopy and Auger electron spectroscopy that were able to detect, of all the non-ferrous metals, only Cu on the sample’s surface.
The effect of temperature (from 288 to 308 K) and concentration of sulfide ions (up to 40 ppm) on the corrosion behavior of AISI 304L and AISI 316L stainless steels in seawater was studied with ...measurements of open-circuit potential, linear and potentiodynamic polarization, and electrochemical impedance spectroscopy. An increase in temperature and pollutant concentration negatively affects the corrosion stability of stainless steels at the open circuit (the resistance, compactness, and thickness of the surface layer decrease and the corrosion current increases), in the passive region (the passivation current increases, the depassivation potential decreases, and the passive potential region narrows), and in the transpassive potential region (the rate of metal dissolution increases). The occurrence of pitting corrosion on the surface of the samples was confirmed with optical microscopy and a non-contact 3D profilometer. A few large pits (depth 80–100 μm and width 100 μm) were formed on the surface of AISI 304L steel, while several smaller pits (depth 40–50 μm and width 50 μm) were formed on the surface of AISI 316L steel. With increasing temperature and sulfide ion concentration, the width, depth, and density of the pits increased on both steel samples. In the studied temperature and concentration range of sulfide ions, the AISI 316L steels exhibited higher corrosion resistance. Overall, the influence of sulfide ions on steel corrosion was more pronounced than the influence of temperature.
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