A History of Materials and Technologies Development

The purpose of the book is to provide the students with the text that presents an introductory knowledge about the development of materials and technologies and includes the most commonly available information on human development. The idea of the publication has been generated referring to the materials taken from the organic and non-organic evolution of nature. The suggested texts might be found a purposeful tool for the University students proceeding with studying engineering due to the fact that all subjects in this particular field more or less have to cover the history and development of the studied object. It is expected that studying different materials and technologies will help the students with a better understanding of driving forces, positive and negative consequences of technological development, etc

Pažangios inžinerinės medžiagos: savybės, gamyba, taikymas

Vadovėlyje nagrinėjama naujų rūšių medžiagų ar medžiagų grupių, sukurtų pastaraisiais dešimtmečiais, raida ir taikymas įvairiose techninės veiklos srityse. Supažindinama su miltelinių medžiagų gamyba, miltelių mechaninio legiravimo principais ir būdais, įvairios paskirties paviršinėmis dangomis, kietosiomis medžiagomis, medžiagomis elektronikos ir saulės energetikos elementams gaminti, karščiui atsparių lydinių (superlydinių) kūrimo raida. Aprašomos nanokristalinės, superkietosios, fotovoltinės, funkcinių dangų ir kt. medžiagos. Nagrinėjama vidinė medžiagų sandara, jos susidarymo sąlygos, savybės, ypatumai ir gamybos būdai. Vadovėlis padės dėstytojui paskaitų metu kuo suprantamiau perteikti dėstomo dalyko teorines ir praktines žinias, o studentui – kuo geriau įsisavinti dėstomą medžiagą dirbant savarankiškai, formuojant praktinių tyrimų įgūdžius, vystant problemų formulavimo, sistemų, procesų ir jų elementų kūrimo gebėjimus, ugdant saugaus darbo įgūdžius. Vadovėlyje pateikiama medžiaga padės siekti dėstomo dalyko supratimo – gebėjimo suprasti ir interpretuoti mokomąją informaciją; pritaikymo – gebėjimo naudoti išmoktą medžiagą realioms problemoms spręsti; analizės – gebėjimo padalinti informaciją į sudėtines dalis ir ieškoti šių dalių tarpusavio sąveikos; sintezės – gebėjimo dalis sujungti į vieną visumą; įvertinimo – gebėjimo nustatyti medžiagos vertingumą duotam tikslui pasiekti. Knygoje pateikiama informacija gauta iš autentiškų ir medžiagų mokslo bei inžinerijos srityse aukštai vertinamų šaltinių. Prie pateiktos faktinės medžiagos nurodyti literatūros šaltiniai. Autorius neprisiima atsakomybės už šiuose šaltiniuose pateikiamų duomenų tikslumą. Vadovėlis skirtas universitetinių aukštųjų technikos mokyklų technikos specialybių studentams, neuniversitetinių aukštųjų technikos mokyklų (kolegijų) dėstytojams ir studentams bei visiems, besidomintiems medžiagų mokslo raida. Knygos leidimą rėmė Europos Sąjungos struktūrinių fondų paramos 2.5 priemonės projektas „Pirmos pakopos inžinerinių studijų programų atnaujinimas gerinant studijų kokybę, didinant tarptautiškumą ir diegiant inovatyvius mokymo(-si) metodus“ pagal Lietuvos 2007–2013 m. Žmogiškųjų išteklių plėtros veiksmų programos 2 prioriteto „Mokymasis visą gyvenimą“ VP1- 2.2-ŠMM-07-K priemonę „Studijų kokybės gerinimas, tarptautiškumo didinimas“. Projektą rėmė Lietuvos Respublika. Projektą iš dalies rėmė Europos Sąjunga

Investigation into the structure and corrosion resistance of Mg-Al and Mg-Al-Zr coatings produced by magnetron sputtering

Thin cathode layers of 200 nm thickness of Mg-Al and Mg-Al-Zr alloys and pure Zr were formed on glass substrates using a magnetron sputtering technique. X-ray diffraction and atomic force microscopy were used for structure and morphology analysis of magnetron sputtered alloys. The corrosion resistance of the sputtered Mg-Al and Mg-Al-Zr coatings in 0.1 M (NH4)3BO3 and 0.1 M NaCl solution (pH = 8.6), was evaluated according to anodic polarization behavior. Article in Lithuanian. Magnetroninių Mg-Al, Mg-Al-Zr ir Zr dangų struktūros ir korozinio atsparumo tyrimas Santrauka. Plonos, 1–2 μm storio, Mg-Al ir Mg-Al-Zr lydinių ir gryno Zr dangos buvo suformuotos ant stiklinių padėklų magnetroninio nusodinimo metodu. Šių dangų struktūra ir morfologija tirta fizikiniais analizės metodais: rentgeno spindulių difrakcija (toliau – RSD) ir atominės jėgos mikroskopija (toliau – AJM). Korozinis dangų atsparumas vertintas veikiant 0,1 M NH4BO3 ir 0,1 M NaCl tirpalu (pH = 8,6), be to, atlikti anodinės poliarizacijos tyrimai. Magnetroniniu būdu nusodintų dangų korozinis atsparumas lygintas su tradiciniais metalurginiais metodais pagamintų cirkonio ir Mg-Al lydinių koroziniu atsparumu. Nustatytos koreliacijos tarp lydinių struktūros ir korozinio atsparumo. Raktiniai žodžiai: Mg-Al, Mg-Al-Zr lydiniai, magnetroninis nusodinimas, korozija

Influence of the particles velocity on the arc spraying coating adhesion

The article deals with investigation of the influence of spray gun nozzle parameters on sprayed particles velocity and strength of coating adhesion. Four different arc spray nozzles were chosen for research. All variables of the spray process were constant except the air debit. The adhesion of coatings was tested. The results of the test showed the dependence of coating adhesion on particles velocity and contamination

Influence of Vibratory Stress Relief on Residual Stresses in Bridge Structural Members Weldments

The welding process can join two similar materials with a bond that has mechanical properties comparable to the original material. Unfortunately, this process induces residual stresses in the weldment, which, if left untreated, can cause distortion of the part, premature fatigue failure or cracking along the weld. In a cases of cracking in steel bridge structural members were attributed to metal fatigue. The majority of these fatigue cracks are initiated adjacent to a weld. A post-weld heat treatment is the traditional method of relieving these stresses, but is costly and a time consuming process. Heat treatment is required for weldments, which have heavy fatigue loading since the post-weld heat treatment reduces the residual stresses in the weldment and generates more uniform mechanical properties. Vibratory stress relief techniques could be used to substitute the heat treatment for these types of weldments and save time and money. The purpose of this paper is to provide a brief overview of the generation, measurement, and reduction of residual stresses. Residual stresses in the weld bead were measured by means of X-ray diffraction, neutron diffraction, ultrasonic technique, hole drilling and numerical methods. In addition, welded specimens were subjected to mechanical testing with purpose of determination of VSR effect on weld and heat-affected zone metal

The influence of temperature-time parameter of welded joints thermal treatment on strength-related characteristics of chromium-molybdenum and low-alloy manganese steels

The article deals with the analysis of the dependence of strength-related characteristics of welded joints from chromium-molybdenum steel (ASTM A335 Grd. P5) and low-alloy manganese steel (S355J2G3 EN10025-2) upon the parameters of heat treatment. Steel mechanical properties after post-weld heat treatment were analyzed. Chromiummolybdenum (Cr – 5 %) steel and structural low-alloy manganese steel (Mn – 1.4 %) was selected as a target. The steels of various classes widely applicable in oil industry were selected. At the beginning, samples were welded applying the same process. When welded, all the samples were heat treated. Tempering for each sample was performed by applying different temperature and exposure time. For analysis systemization the parameter of temperature-time P was applied. It was calculated for each heat treatment mode. After post-weld heat treatment each sample was tested subject to tensile and impact strength. P-dependence of mechanical properties of each steel sample was examined. It was determined that tensile strength and impact strength decreases by increasing P value. It showed the drop of mechanical properties value upon considerable increase of tempering temperature or application of a very long exposure time. Keywords: welded joints, temperature-time parameter, tempering, tensile strength, impact strength

The strength-related characteristics of chromium-molybdenum P5 steel dependence on postweld heat treatment parameters

The article deals with the analysis of chromium-molybdenum steel (ASTM A335 Grd. P5) joints after post weld heat treatment. The finished welds typically exhibit high levels of tensile residual stresses. The risk of weld failure may be alleviated by reducing the magnitude of the tensile residual stresses. The objective of the research program outlined in this paper is to develop a short-term postweld heat treatment procedure than can be used to produce the highest values of strength-related characteristics of welded joint. The article materials present the investigation of the strength-related characteristics dependence on temperature-time parameter P. The welded joints samples were heat treated by tempering mode. When performing post weld heat treatment, the temperature was changed from 500 to 800 degrees C and the exposure (hold) time was changed from 1 to 8 hours. The chosen tempering parameters were to ensure the value of the temperature and time parameter was from 15.5 to 22.5. After post-weld heat treatment each sample was tested subject to tensile, yield and impact strength

The structure and properties of 5 % Cr-0.5 % Mo steel welded joints after natural ageing and post-weld heat treatment

The article deals with the ageing and heat treatment influence on operational reliability of 5 % Cr-0.5 % Mo steel welded joints and pipeline elements. Separate components of the pipelines in the refineries are manufactured from chromemolybdenum 5 % Cr-0.5 % Mo alloy steel. Reduction of internal stresses in chrome-molybdenum steel welded joints can be provided only by thermal treatment. Other methods of stress relieving are not acceptable for these steels. Presented materials analyses the impact of heat treatment on the microstructure and operational reliability of this steel. The objects of research are heat-treated welded joints of piping elements operated at high temperature for an extensive period of time, where degradation of mechanical properties has been observed. When value of the heat treatment temperature or time are exceeded, the structure degradation process is taking place, carbides coagulate within the boundaries of ferrite grains, they form coarse carbide colonies combined into long chains. Mechanical properties – tensile strength and impact strength decrease. Detailed analysis of these objects and the interpretation of the received results allow to select the most appropriate heat treatment parameters for the investigated steel structures

Recent developments in the deposition of c-BN coatings

Cubic boron nitride, c-BN, due to the high strength of its covalent inter-atomic bond, small bond distance, and high coordination number, is the second hardest (HV ≈ 50 GPa) material (the first is diamond with HV ≈ 70 – 90 GPa) available as single crystal. The fact that c-BN does not react readily with ferrous metals, cobalt and nickel; can be deposited in thin film form under standard conditions (1 bar, 298 K); and has a high resistance to oxidation in air to high temperatures of 1000°C, makes it very attractive for tool applications. Unfortunately c-BN films due to high compressive stress, which can reach values up to 25 GPa and poor adhesion strength of the interface, still reveal themselves to be poor adherent to almost every substrate material