Deformation of Aluminium Bronze by HPT and ECAP Methods

Aluminium bronzes BA1032 having a multiphase microstructure, is low-deformable materials with strength close to that of high-strength steels. The influence of high-pressure torsion (HPT) and equal channel angular pressing (ECAP) on aluminium bronze structure was presented. The HPT method was found to be unsuitable for the processing of the investigated aluminium bronzes. The studies have indicated that it is possible to deform multiphase aluminium bronzes BA1032 in the ECAP process at a temperature of 400-500°C. The deformation of the bronzes at lower temperatures encounters some difficulties cracks appear which make repeated ECAP impossible

Analysis of the Industrial Process of Producing a Lever-Type Forging Used in Motorcycles

The article presents an analysis of the multi-operation hot die forging process, performed on a press, of producing a lever forging used in the motorcycles of a renowned producer by means of numerical simulations. The investigations were carried out in order to improve (perfect) the currently applied production technology, mainly due to the presence of forging defects during the industrial production process. The defects result mainly from the complicated shape of the forging (bent main axis, deep and thin protrusions, high surface diversity in the cross section along the length of the detail), which, during the filling of the die by the deformed material, causes the presence of laps, wraps and underfills on the forging. Through the determination of the key parameters/quantities during the forging process, which are difficult to establish directly during the industrial process or experimentally, a detailed and complex analysis was performed with the use of FEM as well as through microstructure examinations. The results of the performed numerical modelling made it possible to determine: the manner of the material flow and the correctness of the impression filling, as well as the distributions of temperature fields and plastic deformations in the forging, and also to detect the forging defects often observed in the industrial process. On this basis, changes into the process were introduced, making it possible to improve the currently realized technology and obtain forgings of the proper quality as well as shape and dimensions

Wear analysis of upsetting inserts during forging under industrial conditions

Intensywność zużycia narzędzi w procesach kucia na gorąco zależy głównie od warunków procesu oraz od materiału narzędzi. Duża ilość i różnorodność czynników wpływających na trwałość matryc oraz ich wzajemne oddziaływanie powoduje, że zagadnienie to jest bardzo trudne do analizy. W pracy opisano zjawiska zachodzące na powierzchni matryc do spęczania swobodnego na gorąco. Na skutek długotrwałej pracy narzędzia, niezależnie od ilości wytworzonych odkuwek, najbardziej intensywne zużycie zachodzi w miejscu najdłuższego kontaktu z kutym materiałem. Przeprowadzono analizę wymiarów za pomocą skanowania powierzchni roboczych narzędzi. Następnie z każdej matrycy pobrano wycinek do badań. Wybrane zostały charakterystyczne obszary na rozwinięciu profilu narzędzia wzdłuż promienia. W obszarach tych wykonano pomiar twardości oraz dokonano obserwacji mikrostruktury w warstwie wierzchniej, a także zmian powierzchni przy użyciu mikroskopu skaningowego. Niebezpiecznym sposobem zużycia narzędzi podczas kucia na gorąco jest odkształ- cenie plastyczne oraz zmęczenie cieplno-mechaniczne, które prowadzi do powstania małych pęknięć. Dalszy ich rozwój, uwarunkowany parametrami procesu, interakcją między matrycą a odkuwką, prędkością płynięcia materiału, prowadzi najczęściej do powstania wtórnej siatki pęknięć na całej powierzchni kontaktu. W świetle badań, ogólnie przyjęty pogląd, że dominującym mechanizmem zniszczenia matryc w procesie kucia na gorąco jest zużycie ścierne, jest dyskusyjny. Wykazano, że mechanizmy takie, jak: cieplno-mechaniczne pękanie, zużycie ścierne oraz odkształcenia plastyczne występują równocześnie od samego początku procesu i mogą być (w danych warunkach) mniej lub bardziej intensywne.The intensity of tool wear in hot forging processes mainly depends on the conditions of the process and on the material from which a tool is made. The large number and variety of factors having an impact on die lifetime and their mutual interaction makes this a problem that is very difficult to analyze. This paper describes phenomena occurring on the surface of dies for hot open die upset forging. As an effect of long-term tool work, regardless of the number of produced forgings, the most intensive wear takes place at the point of longest contact with the forged material. Analysis of dimensions was conducted by scanning of tools’ working surfaces. Next, a slice was collected for testing from each die. Characteristic areas were selected on the development of the tool’s profile along its radius. Hardness measurement was performed in these areas, and the microstructure in the surface layer and changes in the surface were examined under a scanning electron microscope. Plastic deformation and thermomechanical fatigue are dangerous tool wear mechanisms during hot forging, which lead to the formation of small cracks. The further development of these cracks, conditioned by process parameters, interaction between the die and forging, and material flow rate, most often leads to the formation of a secondary network of cracks on the entire contact surface. In light of this study, the generally accepted view that the dominant mechanism of die destruction in hot forging processes is abrasive wear is called into question. It is shown that mechanisms such as: thermomechanical cracking, abrasive wear, and plastic deformations occur simultaneously from the very beginning of the process and may be (under specific conditions) of greater or lesser intensity

Proces równokanałowego wyciskania kątowego wysokowytrzymałych wielofazowych brązów aluminiowych

The aim of the research was to determine the deformation condition of ECAP process of multiphase high strength aluminium bronze BA1032. The studies have indicated that it is possible to deform multiphase aluminium bronze BA1032 in the ECAP process at a temperature of 400°C and die angle Φ=110°. The deformation of the bronzes at lower temperatures encounters some difficulties - cracks appear which make repeated ECAP impossible. The cracks appear on the top surface of the samples where it contacts the surface of the outlet channel. FEM simulations show that the largest plastic strains occur in this area. The proposed ECAP method of large plastic deformations as applied to the investigated aluminium bronzes makes it possible to obtain very strong refinement especially of eutectoid α+ γ2.Celem pracy było określenie warunków odkształcania w procesie ECAP wysokowytrzymałych wielofazowych brązów aluminiowych. Przeprowadzone badania wskazują na możliwość odkształcania wielofazowych brazów aluminiowych w tym procesie w temperaturze 400 °C dla kąta matrycy Φ=110°. Pewne trudności sprawia odkształcanie brązu w niższych temperaturach, gdyż pojawiają się wówczas pęknięcia, które uniemożliwiają prowadzenie procesu wielokrotnego przeciskania próbek przez kanał katowy. Pęknięcia pojawiaja sie na górnej powierzchni próbek w miejscu kontaktu z powierzchnią kanału wyjsciowego. Jak wykazuje symulacje MES w miejscu tym występują największe odkształcenia plastyczne. Zastosowana metoda dużych odkształceń plastycznych ECAP w przypadku badanych brazów aluminiowych pozwala uzyskać bardzo silne rozdrobnienie głównie eutektoidu α+ γ 2

Growth hormone and milk protein gene polymorphism in relation to the levels of some hormones, enzymes and metabolites in growing dairy cattle

International audienc

National Mythologies in Central European TV Series: How J.R. Won the Cold War

<p>This is the first ever international comparative study of the mythologies which popular TV series in Czechoslovakia/Czech Republic, Hungary, Poland and Romania – made before and after the fall of communism – disseminate in their societies.</p> <p>Comparison of samples of popular television from the 1970s, 1980s and 2000s provides strategically significant material about how these societies think and rationalize, and what their thinking is rooted in. The study proceeds from the premise that popular television series provide a fertile ground of investigation as mass media reflects and shapes social and cultural values.</p&gt

The Effect of Heat Treatment of Forgings Directly from the Forging Temperature on their Properties

The paper presents a prototype semi-industrial cooling line developed by the authors, which makes it possible to design a thermal treatment of forgings with the use of the forging heat, together with exemplary test results for forgings forked type. The proposed method of heat treatment dedicated to these forgings was described and compared to traditionally used heat treatment method in chamber furnaces. Next, the original research stand was presented, which performs mechanical fatigue test on final products – forked-type forgings. Forgings after heat treatment and cooling on the prototype line were tested on this stand in condition of cyclically variable mechanical loads in order to resistance to mechanical fatigue was analyzed and the influence of performed exemplary heat treatment on mechanical properties. The presented preliminary investigations performed on the designed combined research standing, consisting of: the prototype controlled cooling line, as well as mechanical fatigue stand point to the possibility of implementing thermal treatment with the use of the heat generated during the forging process and determining its impact on the mechanical properties of forgings

Improving durability of hot forging tools by applying hybrid layers

This paper deals with problems relating to the durability of the dies used for the hot forging of spur gears. The results of industrial tests carried out on dies with a hybrid layer (a nitrided layer (PN) + physical vapor deposition (PVD) coating) applied to improve their durability are presented. Two types of hybrid layers, differing in their PVD coating, were evaluated with regard to their durability improvement effectiveness. The tests have shown that by applying hybrid layers of the nitrided layer/PVD coating type one can effectively increase the durability of hot forging tools