Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 22

Liczba wyników na stronie
first rewind previous Strona / 2 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  wear resistant alloys
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 2 next fast forward last
1
EN
High prices of tin and its limited resources, as well as several valuable properties characterising Cu-Sn alloys, cause searching for materials of similar or better properties at lower production costs. The influence of various nickel additions to CuSn10 casting bronze and to CuSn8 bronze of a decreased tin content was tested. Investigations comprised melting processes and casting of tin bronzes containing various nickel additions (up to 5%). The applied variable conditions of solidification and cooling of castings (metal and ceramic moulds) allowed to assess these alloys sensitivity in forming macro and microstructures. In order to determine the direction of changes in the analysed Cu-Sn-Ni alloys, the metallographic and strength tests were performed. In addition, the solidification character was analysed on the basis of the thermal analysis tests. The obtained results indicated the influence of nickel in the solidification and cooling ways of the analysed alloys (significantly increased temperatures of the solidification beginning along with increased nickel fractions in Cu-Sn alloys) as well as in the microstructure pattern (clearly visible grain size changes). The hardness and tensile strength values were also changed. It was found, that decreasing of the tin content in the analysed bronzes to which approximately 3% of nickel was added, was possible, while maintaining the same ultimate tensile strength (UTS) and hardness (HB) and improved plasticity (A5).
EN
AISI 52100 bearing steels are commonly used in applications requiring high hardness and abrasion resistance. The bearing steels are working under dynamic loads in service conditions and their toughness properties become important. In order to provide the desired mechanical properties, various heat treatments (austenizing, quenching and tempering) are usually applied. In this study, AISI 52100 bearing steel samples were austenized at 900°C for ½ h and water quenched to room temperature. Then tempering was carried out at 795°C, 400°C and 200°C for ½ h. In order to investigate the effect of heat treatment conditions on wear behavior, dry friction tests were performed according to ASTM G99-05 Standard with a ‘ball-on-disk’ type tribometer. The samples were tested against steel and ceramic counterparts using the parameters of 100 m distance and 30 N load and 0.063 m/s rotational speed. After wear test, the surface characterization was carried out using microscopy. Wear loss values were calculated using a novel optical method on both flat and counterpart specimens.
EN
The paper presents the capabilities of welding techniques to creating properties of wear resistant high chromium cast iron alloy. The use of the right kind of welding sequence allows you to change the structure and properties of the obtained welds. Tests were conducted for one type of additive material in the form of self shielded core wire. In order to determine the effect of the type of welding sequence on the properties of welds performed welding using string bead and weave bead. The resulting weld was tested on hardness and research structure in an optical microscope. In the following studies have been made erosive tests wear of made hardfacing. String beads gave structure rich in carbides and harder about 270 HV of the weld with weave bead. Also, wear resistance was nearly twice as better for welds made with string beads. In the experiment a decisive role in the resistance to wear plays a high hardness of the deposit and the presence of carbides in its structure. Changes in the basic parameters of the deposition process allows for the formation of structure and properties of hardfacing welds in a wide range.
EN
Railway buffers during the operation are staying in almost permanent contact with each other, creating friction node in the point of contact of two railway buffer heads. In consequence of overcoming track curves, turnouts and unevenness of track, the railway buffer heads moves relative to each other causing friction, which results in its wear. When the wear is excessive, it might be a reason to withdrawn vehicle from service, it causes flattening of buffer head, and in consequence its abnormal cooperation. To avoid this phenomenon the buffer heads should be covered with graphitized grease, but this method has many disadvantages. Accordingly, it was found that it would be beneficial to cover the buffer head with bronze using laser cladding. In this article the metallographic and mechanical analysis of the newly created top layer of railway buffer head are presented. In article the results from tribological tests conducted on Amsler test bench are also presented. Based on test results described in article concluded that the layer of bronze coat on working surface of railway buffer head can be beneficial from operational point of view.
EN
In spite of the fact that in most applications, magnesium alloys are intended for operation in environments with room temperature, these alloys are subject to elevated temperature and oxidizing atmosphere in various stages of preparation (casting, welding, thermal treatment). At present, the studies focus on development of alloys with magnesium matrix, intended for plastic forming. The paper presents results of studies on oxidation rate of WE43 and ZRE1 magnesium foundry alloys in dry and humidified atmosphere of N2+1%O2. Measurements of the oxidation rate were carried out using a Setaram thermobalance in the temperature range of 350-480°C. Corrosion products were analyzed by SEM-SEI, BSE and EDS. It was found that the oxide layer on the WE43 alloy has a very good resistance to oxidation. The high protective properties of the layer should be attributed to the presence of yttrium in this alloy. On the other hand, a porous, two-layer scale with a low adhesion to the substrate forms on the ZRE1 alloy. The increase in the sample mass in dry gas is lower than that in humidified gas.
EN
This paper discusses changes in the microstructure and abrasive wear resistance of G17CrMo5-5 cast steel modified with rare earth metals (REM). The changes were assessed using scanning microscopy. The wear response was determined in the Miller test to ASTM G75. Abrasion tests were supplemented with the surface profile measurements of non-modified and modified cast steel using a Talysurf CCI optical profilometer. It was demonstrated that the modification substantially affected the microstructure of the alloy, leading to grain size reduction and changed morphology of non-metallic inclusions. The observed changes in the microstructure resulted in a three times higher impact strength (from 33 to 99 kJ/cm2) and more than two times higher resistance to cracking (from 116 to 250 MPa). The following surface parameters were computed: Sa: Arithmetic mean deviation of the surface, Sq: Root-mean-square deviation of the surface, Sp: Maximum height of the peak, Sv: Maximum depth of the valley, Sz: Ten Point Average, Ssk: Asymmetry of the surface, Sku: Kurtosis of the surface. The findings also indicated that the addition of rare earth metals had a positive effect on the abrasion behaviour of G17CrMo5-5 cast steel.
EN
The welding technologies are widely used for design of protection layer against wear and corrosion. Hardfacing, which is destined for obtaining coatings with high hardness, takes special place in these technologies. One of the most effective way of hardfacing is using self shielded flux cored arc welding (FCAW-S). Chemical composition obtained in flux cored wire is much more rich in comparison to this obtained in solid wire. The filling in flux cored wires can be enriched for example with the mixture of hard particles or phases with specified ratio, which is not possible for solid wires. This is the reason why flux cored wires give various possibilities of application of this kind of filler material for improving surface in mining industry, processing of minerals, energetic etc. In the present paper the high chromium and niobium flux cored wire was used for hardfacing process with similar heat input. The work presents studies of microstructures of obtained coatings and hardness and geometric properties of them. The structural studies were made with using optical microscopy and X- ray diffraction that allowed for identification of carbides and other phases obtained in the structures of deposited materials. Investigated samples exhibit differences in coating structures made with the same heat input 4,08 kJ/mm. There are differences in size, shape and distribution of primary and eutectic carbides in structure. These differences cause significant changes in hardness of investigated coatings.
8
Content available Abrasion Wear Behavior of High-chromium Cast Iron
EN
High-chromium cast irons are used as abrasion resistant materials. Their wear resistance depends on quantity of carbides and the matrix supporting these carbides. The paper presents the results of cast irons of chemical composition (in wt. %) 19–22 Cr and 2–4.5 C alloyed by 1.7 Mo + 5 Ni + 2 Mn to improve their toughness, which were tested in working conditions of ferroalloys crushing. Tests showed that these as-cast chromium cast irons with mostly austenitic matrix achieved the hardness of 38-45 HRC, but their relative abrasion resistance Ψ ranged from 1.3 to 4.6, was higher comparing to the tool made from the X210Cr12 steel heat treated on hardness 61 HRC. The transformation of austenite into martensite occurs not only at the worn strained areas (on a surface of scratch) but also in their neighbourhood. Due to the work hardening of relatively large volumes of transformed austenite the cast iron possesses high abrasion resistance also on the surfaces where low pressures are acting. The tough abrasion-resistant cast iron well proved for production of dynamic and wear stressed castings e.g., crusher hammers, cutting tools for ceramic etc.
PL
W części badawczej zaproponowano kilka rodzajów tworzyw (żeliwo ADI – które poddano czterem rodzajom obróbki cieplnej, staliwo manganowe oraz staliwo niklowo-miedziowe), zastosowanie których powinno zapewnić odpowiednią trwałość roboczych elementów maszyn pracujących w oczyszczalniach ścieków, przy jednoczesnym obniżeniu ich ceny. Omówiono pokrótce te tworzywa. Opracowano technologię wykonania form na przedmiotowe elementy. Przeprowadzono obróbkę wykańczającą wykonanych odlewów. Dokonano pomiaru twardości, następnie odlewy przekazano do pracy w oczyszczalni ścieków, gdzie po ich zamontowaniu prowadzone były badania eksploatacyjne.
EN
In the research part of this study, several types of materials were proposed, including ADI (Austempered Ductile Iron) subjected to four different types of heat treatment, using cast manganese steel and cast nickel-copper steel. The use of these materials should provide adequate performance life to machine parts operating in wastewater treatment plants while also reducing the cost of manufacture. The selected materials were briefly discussed. A mould making technology was developed to make the respective cast parts. Castings were subjected to a finishing treatment and after hardness measurements were transferred to a wastewater treatment plant, where they were assembled to carry out the field tests.
PL
Celem pracy było porównanie korozyjnego zachowania się najbardziej popularnego stopu tytanu Ti-6Al-4V, stosowanego na implanty biomedyczne, ze stopem Ti-10Mo-4Zr. Badania odporności korozyjnej zostały przeprowadzone w fizjologicznym roztworze Hank’a. Odporność korozyjną obu stopów porównano na podstawie badań potencjału korozyjnego i potencjo dynamicznych krzywych polaryzacyjnych wykonanych techniką liniowej woltamperometrii (LSV). Stop tytanu Ti-10Mo-4Zr posiada niższy moduł Younga wynoszący 74 ÷ 86 GPa niż stop Ti-6Al-4V (110 GPa). Jest wskazane, aby materiały metaliczne stosowane w implantologii wykazywały moduły Younga raczej niższe, to znaczy zbliżone do modułu Younga kości około 30 GPa. W związku z tym, biorąc pod uwagę właściwości mechaniczne, stop Ti-10Mo-4Zr jest bardziej atrakcyjnym materiałem przeznaczonym na implanty. Badania odporności korozyjnej w fizjologicznym roztworze Hank’a wykazały jednoznacznie, że stop Ti-10Mo-4Zr, podobnie jak stop Ti-6Al-4V, wykazuje bardzo dobra odporność na korozję. Wysoka odporność obu stopów tytanu jest związana z tworzeniem się termodynamicznie stabilnej i trwałej warstwy tlenkowej zawierającej głównie tlenek tytanu TiO2. Bardzo dobra odporność na korozję i korzystniejsze właściwości mechaniczne wskazują, że jednofazowy stop Ti-10Mo-4Zr jest bardzo atrakcyjnym materiałem przeznaczonym na implanty biomedyczne.
EN
The aim of this paper was the comparison of the corrosion behavior two titanium alloy Ti-6Al-4V and Ti-10Mo-4Zr. Up to now Ti-6Al-4V alloy is common used as a bioimplants. Corrosion resistance tests for both Ti alloys have been performed in Hank's physiological solution. Corrosion resistance of both alloys were compared on the basis of the corrosion potential measurements and polarization curves obtained by means of linear voltammetry technique (LSV). Titanium alloy Ti-10Mo-4Zr has a lower Young’s modulus of about 74 GPa compare to Ti-6Al-4V alloy (110 GPa). It is desirable that the metallic materials used for implants should have a rather low Young's modules that is similar to the Young's modulus of human bones (30 GPa). Therefore, considering the mechanical properties the Ti-10Mo-4Zr alloy is very attractive as a material for bioimplants. The study of corrosion resistance in Hank's physiological solution clearly showed that the Ti-10Mo-4Zr like Ti 6Al-4V-shows very good resistance to corrosion. High corrosion resistance of both titanium alloys is related to the formation of thermodynamically stable oxide layer consists mainly of titanium dioxide TiO2. Very good corrosion resistance and favorable mechanical properties indicate that the single-phase Ti-10Mo-4Zr alloy is a very attractive material for biomedical implants.
EN
The theoretical part of the study discloses the genesis of the research which originated from a possibility of replacing the so far used expensive machine parts with parts cheaper and yet offering similar quality and performance life. A short characteristic of the machine was given where the main operating parts made so far from steel were replaced with parts made from cast iron. The equipment and its main applications were described. In the research part of the study several types of alloys were proposed. Their use is expected to ensure the required performance life of parts combined with price reduction. A short characteristic of the proposed material was given. A technology of making moulds for the said machine parts was developed. Using this technology, the respective moulds were made and poured next with three cast alloys. One of the proposed materials was subjected to four types of the heat treatment, two alloys used as reference materials were left in as-cast state. The castings were fettled and weighed. The hardness of the cast materials was measured. The working (turning) parts were delivered for operation to a sewage-treatment plant where, after assembly in a turning machine, the performance tests were conducted.
EN
Materials for mill rolls, fulfilling high requirements due to difficult exploitation conditions, are cast steels of adamite grade. Those are cast steels of pearlitic matrix with uniformly distributed cementite precipitations (e.g. hypereutectoid). In respect of a microstructure and a chemical composition these steels are hypereutectoid steels. They contain chromium (app. 1 %) and nickel (app. 0.5 %) and sometimes have an increased content of silica. Admissible is also a content of Mo (app. 0.4 %). An uniformly distributed carbide phase can be obtained by the proper heat treatment. The determination of the heat treatment influence on tribological properties - in dependence of the applied load - of adamite hypereutectoid G155CrNiMo4-3-3 cast steel, used for mill rolls - was the aim of the hereby paper. The purpose of the applied heat treatment was to change the hypereutectoid cementite morphology. Tribological tests were carried out at a room temperature by means of the T-05 tester, at loads of: 50, 100 and 150 N. Bearing steel 100Cr6 of a hardness 57 HRC was used as a counter sample. Testing time was 400 seconds. During the test the abrasion products were being removed from the counter sample. The performed investigations allow to draw conclusions regarding the influence of the hypereutectoid cementite morphology and loads on a wear mechanism and intensity of wearing of hypereutectoid adamite cast steel.
13
Content available remote Influence of a matrix on properties of mottled cast iron applied for mill rolls
EN
Mill rolls are ones of the most expensive tools applied in plastic working processes and have to satisfy several criteria, which allow them to be used. Cast iron mill rolls, due to their fracture toughness and tribological properties, are the most often applied at hot-rolling in the last rolling stands. This results from the smallest dynamic loads of such rolling stands and the decisive influence of the surface quality of these tools on the surface quality of the rolled product. An improper microstructure of rolls can lead to their premature wearing, e.g. broken flanges, pivots twisting off etc. By means of the heat treatment the matrix microstructure and morphology of carbide precipitations can be modified and this in-turn can influence cast iron properties. Determination of the influence of microstructure changes, caused by the heat treatment, on the properties of EN-GJN-HV300 low-alloy cast iron, after its modification and spheroidization – is the aim of the present paper. Those changes are based on the formation pearlitic or bainitic matrices at the similar morphology of graphite and ledeburitic cementite precipitations. The performed investigations should enable designing the heat treatment of cast iron metallurgical rolls in such a way as to obtain the optimal microstructures for functional parameters of these type of tools. The influence of changing the pearlitic matrix into the bainitic one on such properties as: hardness, impact strength, tensile strength, creep limit, bending strength and a stress intensity factor KIc was investigated in this study. Samples for testing, the listed above mechanical properties, were taken from an industrial casting with care to have pieces of very similar crystallization conditions.
14
Content available remote Heat-resisting alloys for hard surfacing and sealing pad welding
EN
The paper deals with heat-resisting alloys used to harden surfaces of elements operating in increased temperatures. It also deals with alloys used to seal cooperating surfaces of elements operating in the conditions of increased temperatures and aggressive utilities. Application methods and properties of thus obtained layers have been presented and adhesion of layers with matrix material has been assessed.
15
Content available remote Characteristic of intermetallic phases in cast dental CoCrMo alloy
EN
Apart from chromium and molybdenum, casting alloys of cobalt usually contain also up to 0.35 % of carbon. With significant content of carbon, presence of carbide-forming alloying elements results in creating carbide phases. These alloys are characterised by dendritic structure of solid solution of chromium and molybdenum in cobalt with interdendritically precipitated carbides. Because of high chromium content, dominating are M23C6-type carbides, but chromium-rich carbides can be also of M7C3 and M3C2-types. The other elements in the alloy result in creating M6C and MC-type carbides. In the case of low carbon content, creating carbides and forming intermetallic phases based on the alloying elements and cobalt become limited. The presented research was aimed at characterising structure of the cobalt-based dental alloy containing trace quantity of carbon. Characterised were intermetallic phases hardening the alloy. Microscopic examinations using light microscopy, SEM and TEM were carried out. Chemical microanalysis of the precipitates using X-ray analyser EDS was performed, as well as phase analysis using selected area electron diffraction.
16
Content available remote Wear resistance of cast iron
EN
In this paper investigations of abrasive and adhesive wear resistance of different cast iron grades have been presented. Examinations showed, that the most advantageous pair of materials is the cast iron - the hardened steel with low-tempered martensite. It was found, that martensitic nodular cast iron with carbides is the most resistant material.
17
Content available remote Structural and strength characteristics of wear-resistant martensitic steels
EN
The paper presents structural, strength and impact resistance characteristics of a construction materials group. These are low-alloy steels of martensitic type structure, showing very high strength moduli, high wear resistance in the dynamic load conditions, and good weldability. Subject of the studies has been the most commonly used group of Hardox steels (Hardox 400 and Hardox 500), as well as the Polish equivalents of those materials (HTK 700 and HTK 900). It has been shown that despite similarity of chemical composition and production processes, the steels differ somewhat in structure, which influences their strength and usability (an operating experiment has been performed). Unfavourable structural changes in welded joints deteriorate their operating properties in the heat-affected zones, and cause clear drop in the wear resistance, despite the application of welding procedures recommended by a producer. The work presents synthesis of knowledge on that modern and still not well recognized group of steels, documented with results of own studies.
EN
This paper deals with the role of the microstructure in the tribological wear processes occurring in a cast iron mill roll. For this purpose, a piece of a broken roll, made in Italy, was collected. Its microstructure consisted of modular graphite, transformed ledeburite and a matrix composed of bainite and martensite. Metallographic investigations were performed on the roll working surface in conjunction with metallographic tests effected within its surface layer. There was established the relation between the microstructure of the roll and the process of its tribological wear. The following was ascertained: micro-shrinkages or graphite precipitations nearby the working area cause cracks between those places and the working area; in the surface layer, cracks occur usually in the zone of ledeburitic cementite. At places of considerable precipitations of ledeburitic cementite, the tribological wear intensity of the roll is lower. A banded layout of precipitations of ledeburitic cementite facilitates a selective spalling of some parts of the roll material. The results of this study allow broadening the data base related to the effect of the microstructure on tribological wear of mill rolls, which in future will permit one to design their proper microstructure of cast iron mill rolls.
19
Content available remote Effect of boron carbide on primary crystallization of chromium cast iron
EN
In the paper results of the influence of boron carbide (B4C) as inoculant of abrasion-resisting chromium cast iron (about 2,8% carbon and 18% chromium) on primary crystallization researches are presented. Boron carbide dispersion was introduced at the bottom of pouring ladle before tap of liquid cast iron. In this investigations were used three different quantities of inoculant in amounts 0,1%; 0,2% and 0,3% with relation to bath weight. It has been demonstrated that such small additions of boron carbide change primary crystallization parameters, particularly temperature characteristic of process, their time and kinetics.
EN
The theoretical part of the study discloses the genesis of the research which originated from a possibility of replacing the so far used expensive machine parts with parts cheaper and yet offering similar quality and performance life. A short characteristic of the machine was given where the main operating parts made so far from steel were replaced with parts made from cast iron. The equipment and its main applications were described. In the research part of the study several types of alloys were proposed. Their use is expected to ensure the required performance life of parts combined with price reduction. A short characteristic of the proposed material was given. A technology of making moulds for the said machine parts was developed. Using this technology, the respective moulds were made and poured next with three cast alloys. One of the proposed materials was subjected to four types of the heat treatment, two alloys used as reference materials were left in as-cast state. The castings were fettled and weighed. The hardness of the cast materials was measured. The working (turning) parts were delivered for operation to a sewage-treatment plant where, after assembly in a turning machine, the performance tests were conducted.
first rewind previous Strona / 2 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.