7. Biological Effectiveness of 12 C and 20 Ne Ions with Very High LET

Knowledge of radiobiological effects of heavy ions at the cellular and molecular level is of fundamental importance in the field of radiation therapy (for example C ions) and space radiation biology (for example Ne ions). One of the issues that require deeper investigations is a determination of RBE values for a wide range of LET, for all relevant doses, for many cell types and various kinds of radiations During recent years, the biological effectiveness of heavy ions has been widely investigated with the aim to identify physical characteristics relevant to biological actions. These investigations are pertinent to the use of heavy ions in radiosurgery and radiotherapy. What has not been investigated so thoroughly is the biological effectiveness of heavy ions at low energies and very high LET values. The LET, which is equal to the stopping power of heavy particles, increases sharply at the end of the particle's path, forming a so-called Bragg peak. The shape of the Bragg peak depends on the particle type. Because overlying beams with different energies and components of primary and secondary particles are used in radiotherapy, the knowledge of RBE values of very high LET radiation need to be well characterized. An experimental set-up designed for such investigations was constructed at the isochronic cyclotron in Heavy Ion Laboratory. A more detailed description of the set-up can be found in Ref. CHO-K1 cells have been used as a suitable biological system for our studies. The cell line is characterized by genetic stability, the ability to form colonies, a relatively rapid growth rate with a cell cycle of 12-14 hours. For exposure to ions the cells were seeded in specially designed Petri dishes, which were filled with medium, sealed by a parafilm cover and placed in a vertical sample holder mounted in an x-y-z table that was connected to a special stepping motor. The irradiated sample moved under the beam according to a planned route. Movement was initiated when the number of counts detected by the 20 o particle detector reached the preset value. When all fields have been exposed the sample holder returned to the start position. Stored information enabled to evaluate the beam stability and intensity. The whole set-up was surveyed by a digital camera. The total time of exposure per dish was between 1-5 min. depending on the dose and beam intensity. The dose rates were changed from 0.05 Gy/min. to 1 Gy/min depending on the dose. Cell survival was estimated according to standard procedure

Effect of Technical Quality of Thermomechanical Die Forging of AA2099 Alloy

The paper presents the results of investigations of a multicomponent third-generation aluminium alloy, classified as AA2099. The actual forging conditions were determined basing on the assessment of the quality of side surface of specimens subjected to compression in Gleeble 3800 simulator and on flow curves of the alloy, as well as numerical modelling of forging process performed with application of QForm 3D v.7 software. Compression tests were realized at temperatures 400-500 °C, with a strain rate of 0.001-100 s-1, up to a specified constant true strain value of 0.9. Microstructure examination in as-delivered state was performed with application of Leica DM 4000M optical microscope. The obtained results of isothermal deformation of specimens were correlated with the analysis of a characteristic layered pancake-type microstructure. The simulation of die forging of a complex-shape forging (high-current contact tip used in power engineering) at the temperature 500 °C, was performed. The shape of a forging makes it possible to fully analyse the influence of thermomechanical process conditions on technical quality of a product. The simulation of forging process showed full correctness of material flow, with no signs of instability. At the same time, the analysis of investigations allowed to prepare and realize the industrial forging trials for a forging of a very complex shape, in a single step, at the temperature 500 °C, with application of thermomechanical treatment. The forging attained high quality of shape and surface. Directional specimens were taken, in order to be subjected to microstructure examination and hardness testing. The data obtained from industrial tests, combined with the results of testing using Gleeble simulator as well as from numerical modelling, make up the guidelines for mechanical processing of AA2099 alloy at the temperatures 470-500 °C

Effect of Technical Quality of Thermomechanical Die Forging of AA2099 Alloy

The paper presents the results of investigations of a multicomponent third-generation aluminium alloy, classified as AA2099. The actual forging conditions were determined basing on the assessment of the quality of side surface of specimens subjected to compression in Gleeble 3800 simulator and on flow curves of the alloy, as well as numerical modelling of forging process performed with application of QForm 3D v.7 software. Compression tests were realized at temperatures 400-500 °C, with a strain rate of 0.001-100 s-1, up to a specified constant true strain value of 0.9. Microstructure examination in as-delivered state was performed with application of Leica DM 4000M optical microscope. The obtained results of isothermal deformation of specimens were correlated with the analysis of a characteristic layered pancake-type microstructure. The simulation of die forging of a complex-shape forging (high-current contact tip used in power engineering) at the temperature 500 °C, was performed. The shape of a forging makes it possible to fully analyse the influence of thermomechanical process conditions on technical quality of a product. The simulation of forging process showed full correctness of material flow, with no signs of instability. At the same time, the analysis of investigations allowed to prepare and realize the industrial forging trials for a forging of a very complex shape, in a single step, at the temperature 500 °C, with application of thermomechanical treatment. The forging attained high quality of shape and surface. Directional specimens were taken, in order to be subjected to microstructure examination and hardness testing. The data obtained from industrial tests, combined with the results of testing using Gleeble simulator as well as from numerical modelling, make up the guidelines for mechanical processing of AA2099 alloy at the temperatures 470-500 °C

Effect of Processing Conditions on Forgeability and Properties of Hot and Warm-Forged Steel 300M

Results of investigation of the effect of processing conditions of medium-carbon alloy steel AISI 300M on forgeability and microstructure-properties are presented here, including as-forged and heat treated condition of the material. The presented results concern two vital aspects of plastic forming of high-duty impression-die forgings, which underlay a selection of technological conditions which enable the accomplishment of the required quality of the forged part. These are: firstly, the microstructure and mechanical properties and their uniformity within a part and secondly, technological realization of forging the required geometry in the given processing conditions

Effect of Processing Conditions on Forgeability and Properties of Hot and Warm-Forged Steel 300M

Results of investigation of the effect of processing conditions of medium-carbon alloy steel AISI 300M on forgeability and microstructure-properties are presented here, including as-forged and heat treated condition of the material. The presented results concern two vital aspects of plastic forming of high-duty impression-die forgings, which underlay a selection of technological conditions which enable the accomplishment of the required quality of the forged part. These are: firstly, the microstructure and mechanical properties and their uniformity within a part and secondly, technological realization of forging the required geometry in the given processing conditions. In order to define a favourable processing window, dynamic behaviour modeling in variable forging conditions was carried out, establishing a coefficient of energy dissipation η% and the metal flow instability areas, which indicated the temperature regime and strain rate range for the forging process. The constructed processing maps were subject to experimental verification in the die-forging tests, carried out on a screw press. Hot and warm forging conditions were applied accordingly to selected areas of the processing maps, representative for unique forging conditions occurring in the industrial practice

Phase Transitions of Environmental Susceptible Polymer Gels. Part one: General Characteristics, Divisions and Methods of Gels Preparation

W artykule przedstawiono ogólną charakterystykę, podział oraz metody otrzymywania żeli ze szczególnym uwzględnieniem żeli podlegających zjawisku objętościowego przejścia fazowego. Następnie bardziej szczegółowo omówiono zjawisko objętościowego przejścia fazowego żeli. Wspomniano także o praktycznych możliwościach jego zastosowania.The article presents general characteristics and the methods of preparation of gels. Particular attention is given to the gels undergoing the volume phase transition. This transition is illustrated in detail. Possible applications are discussed too

The Phase Transitions of Environmental Flexible Polymeric Hydrogels. Part 2: The Application of Polymeric Hydrogels Properties

Żele polimerowe można zdefiniować jako jedną makrocząsteczkę w postaci sieci polimerowej wypełnioną rozpuszczalnikiem. Zawartość wody w hydrożelach jest zazwyczaj wyższa niż 95%, niemniej jednak materiały te mają właściwości charakterystyczne dla cieczy i ciał stałych. Dzięki swojej specyficznej budowie i wrażliwości na czynniki środowiskowe żele znalazły wiele zastosowań w różnych dziedzinach. W poniższym artykule przedstawiono niektóre z tych zastosowań.Thanks to their properties the polymeric hydrogels are very useful in both, various industrial branches as well as in every day life. Many research teams aim at finding new hydrogels which will have bigger and other applications. They also aim at the synthesis of new hydrogels with strictly defined properties. Those materials should show big sorbing capacity comparing to water solutions and to specified chemical substances. Hydrogels, which undergo phase transition in specified environmental and which are sensitive to other and new environmental factors, have been searched

Numerical modelling of the multistage die forging process

Przedstawiono analizę obliczeń numerycznych procesu kucia matrycowego okuwki wydłużonej kutej w matrycach otwartych na zespole agregatów z zastosowaniem walcowania przedkuwki i kucia na prasie. Obliczenia numeryczne wykonano dla kilku alternatywnych technologii przy założeniu różnych kształtów i masy wsadu. Analizę przeprowadzono uwzględniając rozkład odkształceń, temperatury i parametrów energetycznych procesu kucia oraz wielkości uzysku kuźniczego dla przyjętych technologii.In the paper numerical modelling of the multistage die forging process of connecting-rod was analysed. Numerical calculation was performed for a several alternative technologies with different weight and shape of a billet. In the analysis of the assumed technologies strain, temperature and energy parameters distribution and forging yield have been investigated

Numerical modelling of influence of deformation velocity on forging's parameters of aircraft wheel

Analizie poddano proces kucia odkuwki felgi koła samolotu, charakteryzującej się bardzo dużą powierzchnią w płaszczyźnie podziału matryc, wykonywanej z dwufazowego stopu tytanu Ti-6Al-4V. Warunki brzegowe opracowano dla kilku technologii, przy założonej temperaturze wsadu i narzędzi, tarciu powierzchniowym oraz prędkości odkształcania (prasa hydrauliczna, młot). Ocenę procesu kucia wykonano na podstawie map rozkładu intensywności odkształcenia, temperatury i naprężeń średnich. Otrzymane wyniki są podstawą do określenia parametrów procesu kształtowania w warunkach przemysłowych wyrobów ze stopów tytanu czułych na prędkość odkształcenia.Forging process of aircraft wheel with large surface in parting plane of dies made of two-phase titanium alloy Ti-6Al-4V was analysed. Bonduary conditions was prepeared for several technologies, assums stock forging and tools temperature, friction factor and strain rate which is determined by velocity of tools (hammer and hydraulic press). The process estimation was carried out based on maps of distribution for effective strain rate, temperature and mean stress. The results of analysis are the base for definition forging process in industrial for products in titanium alloys which are sensitive to strain rate

Rozkład odkształceń w procesie wydłużania swobodnego wlewków z wewnętrznymi nieciągłościami

In this paper is presented analysis of cogging process of the 16 Mg ingot in the three-dimensional state of deformation, using commercial program QForm 3D to valuate effective strain distribution. Additionally voids closing were analysed, which were purposely inserted (various diameters and shapes) in selected areas. Numerical calculations were carried out for two following processes: upsetting of the reforged ingot and cogging process. Cogging operation of reforged material was simulated according to two schedules from the head and the bottom side of the ingot. As a criterion of valuation of the cogging process with flat dies were accepted maps of effective strain distribution.W pracy przedstawiono analizę procesu wydłużania swobodnego wlewka o masie 16 Mg w przestrzennym stanie odkształcenia przy wykorzystaniu programu komercyjnego QForm 3D pod kątem oceny rozkładu odkształceń. Dodatkowo analizowano mechanizm zamykania, celowo wprowadzonych - o różnych rozmiarach i kształtach - w wybranych obszarach, wewnętrznych nieciągłości we wlewku. Badania symulacyjne przeprowadzono dla dwóch kolejnych operacji: spęczania wstępnie przekutego wlewka oraz wydłużania. Proces wydłużania spęczonego materiału symulowano według dwóch schematów od strony: uchwytu (głowa wlewka) oraz stopy wlewka. Jako kryterium oceny procesu wydłużania swobodnego w kowadłach płaskich przyjęto mapy rozkładu intensywności odkształcenia