As ligas do sistema Fe-Mn-Al-C constituem-se numa das famílias mais promissoras para o atendimento dos requisitos crescentes de disponibilidade de aços com altas relações resistência/peso, principalmente nas indústrias de transporte aeronáutica e automotiva, visando a redução no consumo de combustível e a consequente emissão de CO2. Suas densidades, cerca de 10% a 13% inferiores aos dos aços convencionais e a possibilidade de aumento de resistência mecânica por tratamentos de endurecimento pela precipitação de carboneto k (Fe,Mn)Al3C possibilitam a obtenção de elevadas resistências específicas. O uso de técnicas da Engenharia de Superfícies, associadas aos tratamentos térmicos adequados, podem ampliar a faixa de desempenho dessas ligas. Neste trabalho foram realizados tratamentos termoquímicos de boretação em sais fundidos, nitrocementação a plasma e cromização por pó em amostras de um aço com a composição Fe-31,2Mn-7,5Al-1,3Si-0,9C (% em peso), visando à obtenção de camadas de elevados desempenhos mecânicos e físicos. As camadas produzidas foram caracterizadas por meio de ensaios micrográficos, de dureza, desgaste e corrosão. Todos os tipos de tratamentos produziram camadas com resistências ao desgaste muito superiores às do substrato, com destaque para os tratamentos de boretação e de cromização, que produziram camadas com resistências ao desgaste cerca de nove e seis vezes superiores às do substrato, respectivamente. O tratamento de cromização produziu camada com resistência à corrosão por pites muito superior à do substrato. / The alloys of the Fe-Mn-Al-C system belong to one of the most promising families to meet the increasing requirements of availability of steels with high resistance/weight ratio, particularly in the aeronautics and automotive industries, aimed at reducing the consumption of fuel and consequent CO2 emissions. Their densities, between 10% to 13% lower than those of conventional steels, and the possibility of increased strength by hardening treatment by the precipitation of k carbides (Fe, Mn)Al3C, allow to obtain high specific resistance. The use of techniques of surface engineering, attached to suitable heat treatment, can extend the performance range of these alloys. In this work were carried out thermochemical boriding treatment in molten salts, plasma nitrocarburizing and pack chromizing in a Fe-31,2Mn 7,5Al-1,3Si-0,9C(wt%) steel, in order to obtain coatings with high mechanical and physical performances. The layers produced were characterized using micrographic, hardness, wear and corrosion tests. All treatments produced layers with wear resistance superior to that the substrate, especially the boriding and chromizing treatments, which produced layers with wear resistance around nine and six times higher than that of substrate, respectively. The chromizing treatment produced layer with pitting corrosion resistance superior to that of the substrate.

Ceramic metal composites, or cermets, currently have widespread applications in the chemical, automotive and oil and gas sectors, due to their combination of high wear resistance, and aqueous corrosion resistance. In the present study, a family of novel titanium carbide (TiC)-stainless steel cermets has been produced as potential materials for use as erosion and corrosion resistant materials. The development of the TiC-stainless steel cermets is based on a simple melt infiltration technique, with the stainless steel “binder” contents varied from 5 to 30 vol.%, using the austenitic grades 304L and 316L, and the martensitic grade 410L. These materials have subsequently been evaluated for their wear and corrosion response, as well as characterisation of their basic mechanical properties and microstructure. Results from wear and corrosion studies show an improvement in wear and corrosion resistance of the cermets at lower steel binder content . / The original abstract from thesis is below. Ceramic metal composites, or cermets, currently have widespread applications in the chemical, automotive and oil and gas sectors, due to their combination of high wear resistance, and aqueous corrosion resistance. In the present study, a family of novel titanium carbide (TiC)-stainless steel cermets has been produced as potential materials for use as erosion and corrosion resistant materials. The development of the TiC-stainless steel cermets is based on a simple melt infiltration technique, with the stainless steel “binder” contents varied from 5 to 30 vol.%, using the austenitic grades 304L and 316L, and the martensitic grade 410L. These materials have subsequently been evaluated for their wear and corrosion response, as well as characterisation of their basic mechanical properties and microstructure. Reciprocating wear tests involved a ball-on-flat geometry (using a WC-Co counter face sphere), with loads varied from 20 to 80 N, for up to 120 minutes. The wear tracks were assessed using a high-resolution optical profilometer, in order to determine the wear volume. The specific wear rate of the cermets was found to increase with both the applied load and the steel binder content. To investigate the morphology of worn surfaces, scanning electron microscopy (SEM), and associated energy dispersive x-ray spectroscopy (EDS) were used, in order to fully understand the operative wear mechanisms. A transition from two- to three-body abrasive wear was observed, together with the formation of a oxygen-rich tribolayer, indicating that adhesive wear was also occurring on the cermets. In order to assess the electrochemical behaviour of the cermets in a simulated seawater environment, the samples were evaluated using potentiodynamic, cyclic and potentiostatic polarisation tests, with basic corrosion parameters and rates subsequently determined through Tafel extrapolation and weight loss measurement. Each stage of electrochemical assessment was then evaluated by characterising the corroded surfaces and solution using SEM, EDS and inductively coupled plasma optical emission spectrometry. Microstructural observations using SEM images revealed significant degradation of the samples, with steel binder preferentially dissolved while TiC remained relatively unaffected. The corrosion rate of the cermets increases with steel binder content, which is attributed to the preferential dissolution of the binder.

As ligas do sistema Fe-Mn-Al-C constituem-se numa das famílias mais promissoras para o atendimento dos requisitos crescentes de disponibilidade de aços com altas relações resistência/peso, principalmente nas indústrias de transporte aeronáutica e automotiva, visando a redução no consumo de combustível e a consequente emissão de CO2. Suas densidades, cerca de 10% a 13% inferiores aos dos aços convencionais e a possibilidade de aumento de resistência mecânica por tratamentos de endurecimento pela precipitação de carboneto k (Fe,Mn)Al3C possibilitam a obtenção de elevadas resistências específicas. O uso de técnicas da Engenharia de Superfícies, associadas aos tratamentos térmicos adequados, podem ampliar a faixa de desempenho dessas ligas. Neste trabalho foram realizados tratamentos termoquímicos de boretação em sais fundidos, nitrocementação a plasma e cromização por pó em amostras de um aço com a composição Fe-31,2Mn-7,5Al-1,3Si-0,9C (% em peso), visando à obtenção de camadas de elevados desempenhos mecânicos e físicos. As camadas produzidas foram caracterizadas por meio de ensaios micrográficos, de dureza, desgaste e corrosão. Todos os tipos de tratamentos produziram camadas com resistências ao desgaste muito superiores às do substrato, com destaque para os tratamentos de boretação e de cromização, que produziram camadas com resistências ao desgaste cerca de nove e seis vezes superiores às do substrato, respectivamente. O tratamento de cromização produziu camada com resistência à corrosão por pites muito superior à do substrato. / The alloys of the Fe-Mn-Al-C system belong to one of the most promising families to meet the increasing requirements of availability of steels with high resistance/weight ratio, particularly in the aeronautics and automotive industries, aimed at reducing the consumption of fuel and consequent CO2 emissions. Their densities, between 10% to 13% lower than those of conventional steels, and the possibility of increased strength by hardening treatment by the precipitation of k carbides (Fe, Mn)Al3C, allow to obtain high specific resistance. The use of techniques of surface engineering, attached to suitable heat treatment, can extend the performance range of these alloys. In this work were carried out thermochemical boriding treatment in molten salts, plasma nitrocarburizing and pack chromizing in a Fe-31,2Mn 7,5Al-1,3Si-0,9C(wt%) steel, in order to obtain coatings with high mechanical and physical performances. The layers produced were characterized using micrographic, hardness, wear and corrosion tests. All treatments produced layers with wear resistance superior to that the substrate, especially the boriding and chromizing treatments, which produced layers with wear resistance around nine and six times higher than that of substrate, respectively. The chromizing treatment produced layer with pitting corrosion resistance superior to that of the substrate.

This thesis is meant to serve as part of a competence platform for future product development projects at Sandvik Coromant AB, Solid Round Tools Department, Västberga, Sweden. The project objective is to gain generic knowledge of the wear mechanisms that restrict tool lifetime when drilling austenitic stainless steel. Thus, identifying if the weakest link of the tool is located within the coating, the coating adherence or in the strength of the substrate. A theoretical review of the work-piece and tool materials has been conducted as a background, along with definition of tool geometry and process parameters. Furthermore, the review includes chemical and process design effect on mechanical properties of the austenitic stainless steel, TiAlN coatings and cemented carbide substrates. Additionally, the basic principles of the wear mechanisms and wear types that are specific to drilling have been reviewed. During the experimental procedures both solid and exchangeable tip drills from cemented carbide with multilayered PVD TiAlN coatings were tested. Two series of tests were conducted, the first series aimed to identify wear type dependency on cutting speed, focusing on wear of the tool margin. The second test series was performed to map the wear progression depending on distance. Analyses including identification the main wear mechanism, quantification the amount of wear, identify wear location on the tool, crack investigation and WDS analysis of chemical wear. Adhesive coating wear was found on the tool margin at an early stage. The adhesive wear rapidly progressed into a stable intermediate stage. Leaving the substrate exposed and more susceptible to other wear types resulting in crack and oxide layer formation.

This research conducts tribological investigation in three areas. The first area of research is to obtain basic understanding of tribological properties of high performance Inconel alloys. Pin-on-disk testing was conducted through a range of applied normal loads and sliding velocities in an unlubricated condition. Average friction coefficient, friction work, and specific wear rates were calculated from the data and microscopy techniques were used to observe and characterize wear mechanisms. Experimental results show a dependence of average coefficient of friction as a function of frictional work. Also shown is the wear rate dependence on frictional work, predicated by a wear mechanism change. This research gives a tribological baseline for high performance alloys. The second area of research is in the in situ spatial study of friction, complemented by monitoring changes in electrical contact resistance (ECR). Pin-on-disk testing of samples was done under low normal loads and velocities. Friction and electrical contact resistance measurements were taken spatially in the wear track during each friction cycle, giving a spatial evolution of friction and resistance change, in situ. Results show a lowering in the ECR under increased friction cycles, which was closely related to a change in the friction coefficient of the material. Using surface profilometry and X-ray Photoelectron Spectroscopy, we determined that the lowering of resistance is a result of surface modification through wear and development of a friction induced conductive tribo-film. This research provides a simple method for in situ monitoring of friction and solidifies a fundamental relationship between friction and contact resistance. The third area of research is the design of a variable force tribometer, incorporating the fundamental results demonstrated in the first two experiments. The creation of a novel testing apparatus to test materials under dynamic tribological conditions is given in detail. Simple experiments were performed on an Inconel sample and preliminary results show how dynamic normal and tangential forces affect the friction coefficient. These early results utilizing the variable force tribometer will lay the groundwork for more advanced research into the dynamic nature of friction.

Metal matrix composites (MMCs) are emerging as advanced engineering materials for application in aerospace, defence, automotive and consumer industries (sports goods etc.). In MMCs, a metallic base material is reinforced with ceramic fiber, whisker or particulate in order to achieve a combination of properties not attainable by either constituent individually. Aluminium or its alloy is favoured as metallic matrix material because of its low density, easy fabricability and good engineering properties. In general, the benefits of aluminium metal matrix composites (AMCs) over unreinforced aluminium alloy are increased specific stiffness, improved wear resistance and decreased coefficient of thermal expansion. The conventional reinforcement materials for AMCs are SiC and AI2O3. In the present work, boron carbide (B4C) particles of average size 40μm were chosen as reinforcement because of its higher hardness (very close to diamond) than the conventional reinforcement like SiC, AI2O3 etc. and of its density (2.52 g cm"3) very close to Al alloy matrix. In addition, due to high neutron capture cross-section of 10B isotope, composites containing B4C particle reinforcement have the potential for use in nuclear reactors as neutron shielding and control rod material. Al-5%Mg alloy was chosen as matrix alloy to utilize the beneficial role of Mg in improving wettability between B4C particles and the alloy melt. (Al-5%Mg)-B4C composites containing 10 and 20 vol% B4C particles were fabricated. For the purpose of inter-comparison, unreinforced Al-5%Mg alloy was also prepared and characterized. The Stir Cast technique, commonly utilized for preparation of Al-SiC, was adapted in this investigation.The Composites thus prepared was subsequently hot extruded with the objective of homogenization and healing minor casting defects. Finally the unreinforced alloy and its composites were characterized in terms of their microstructure, mechanical and thermo-physical properties, sliding wear behaviour and neutron absorption characteristics. The microstructures of the composites were evaluated by both optical microscope and scanning electron microscope (SEM). The micrographs revealed a relatively uniform distribution of B4C particles and good interfacial integrity between matrix and B4C particles. The hot hardness in the range of 25°C to 500°C and indentation creep data in the range of 300°C to 400°C show that hot hardness and creep resistance of Al-Mg alloy is enhanced by the presence of B4C particles. Measurement of coefficient of thermal expansion (CTE) of composites and unreinforced alloy upto 450°C showed that CTE values decrease with increase in volume fraction of reinforcement. Compression tests at strain rates, 0.1, 10 and 100 s-1 in the temperature range 25 - 450 °C showed that the flow stress values of composites were, in general, greater than those of unreinforced alloy at all strain rates. These tests also depicted that the compressive strength increases with increase in volume fraction of reinforcements. True stress values of composites and unreinforced alloy has been found to be a strong function of temperature and strain rate. The kinetic analysis of elevated temperature plasticity of composites revealed higher stress exponent values compared to unreinforced alloy. Similarly, apparent activation energy values for hot deformation of composites were found to be higher than that of self-diffusion in Al-Mg alloy. Tensile test data revealed that the modulus and 0.2% proof stress of composites increase with increase in volume fraction of the reinforcements. Composites containing 10%BUC showed higher ultimate tensile strength values (UTS) compared to unreinforced alloy. However, composites with 20%B4C showed lower UTS compared to that of the unreinforced alloy. This could be attributed to increased level of stress concentration and high level of plastic constraint imposed by the reinforcing jparticles or due to the presence solidification-induced defects (pores and B4C agglomerates ). Sliding wear characteristics were evaluated at a speed of 1 m/s and at loads ranging from 0.5 to 3.5kg using a pin-on-disc set up. Results show that wear resistance of Al-5%Mg increases with the addition of B4C particles. Significant improvement in wear resistance of Al-5%Mg is achieved with the addition of 20% B4C particles. SEM examination of worn surfaces showed no pull-out of reinforcing particles even at the highest load of 3.5 kg, thus confirming good interfacial bonding between dispersed B4C particles and Al alloy matrix. The neutron radiography data proved that (Al-5%Mg)-B4C composites possess good neutron absorbing characteristics. From the experimental data evaluated in the "study, it may be concluded that (Al-5%Mg)-B4C composites could be a candidate material for neutron shielding and control rod application. The enhanced elevated temperature-strength and favourable neutron absorption characteristics of these composites are strong points in favour of this material.

Wear is a commonly occurring degradation mechanism for materials and components in the rock drilling industry. The wear can occur by either abrasion or adhesive wear. Further corrosion and presence of water or other lubricating fluids with or without particles may influence the behavior. Which mechanism, or mechanisms, and under which conditions it occurs, as well as the relative wear rate is dependent on the actual operating conditions for the component. In the present study, commonly available and general test methods for wear on high-alloy carbon steel has been analyzed. The project has been carried out through literature reviews and study visits at the tribology laboratory at KTH and at the Angstroms laboratory at Uppsala University. The present study indicates that it is difficult to suggest a feasible test method that is possible to use for all different situations of the wear that may occur. A test adapted to the actual situation is required to achieve a proper wear rate comparable to the wear rate in a real application.  According to the requirements from Ovako AB, a test that is general, cost effective and can be used when developing steel with higher wear-resistance, following wear testing methods has been compared: a pin-on-disk apparatus, a dry/wet sand/rubber wheel, a dry/wet sand/steel wheel, a tumbling mill, a particle erosion rig, a solid particle impingement using gas jets and a grinding machine. The tumbling mill, the grinder and the “Standard Test Method for Wear Testing with a Pin-On- Disk Apparatus” correspond to the requirements best. Ovako AB is recommended to continue the work with these testing methods. / Nötning är en vanlig mekanism som orsakar nedbrytning på material i gruvindustrin. Nötningen kan förekomma som abrasiv eller adhesiv nötning. Korrosion och närvaro av vatten eller andra smörjande vätskor med eller utan lösa partiklar kan påverka beteendet. Den eller de mekanismer som styr nötningen såväl som nötningstalet beror på de aktuella förhållanden vilka materialet eller materialen verkar i. I denna studie har en generell testmetod för att utvärdera nötning på höglegerat kolstål har undersökts. Arbetet har genomförts genom litteratursökning samt studiebesök vid tribologiska laboratoriet på KTH samt på Ångströmska i Uppsala. Utifrån arbetet har det visat sig att det inte förekommer några generella nötningstest för alla applikationer, då det krävs ett test som är anpassat efter verkligheten för att få ut korrekt nötningstal. Utifrån Ovako ABs önskemål om ett generellt test som är ekonomiskt hållbart samt kan användas för att utveckla nötningsbeständigheten i de stål där nötning förekommer har följande testmetoder jämförts: pinne/skiva-maskin, blött/torrt sand/gummihjul, blött/torrt sand/stålhjul, roterande trumma, ”Erofugen”, partikelsprutare och en slipmaskin. De test som motsvarar kravprofilen bäst är den roterande trumman, slipmaskinen samt den standardiserade pinne/skiva-maskinen. Utifrån dessa testmetoder rekommenderas Ovako AB att fortsätta arbetet.

Adhesive wear occurs when small surfaces of the cutting tool due to friction are micro-welded to the chips and removed from the tool surface. A hypothesis as to whywelding occurs is that an electric potential field arises which initiates a chemical reaction and then welding of the work material and the tool takes place in the cuttingzone. The electric potential field results in a fluttering magnetic field, which in turngenerates electromagnetic issues. The waves should be around and above 1 MHz.The aim of this work is thus to investigate the presence of electromagnetic wavesfrom the cutting zone. The purpose is to compare sound and electromagnetic wavesduring the adhesive process. Previous research shows that the adhesive mechanism is a transient vibration thatmanifests itself as a cluster of waves with a stochastic duration, including a feedbacksystem restricted by the plastic deformation within the chip. Furthermore, the cutting speed is the most important cutting parameter in tool wear and the main wearmechanism at cutting speeds around 200 m/min is the adhesive wear. Several studies showed the emission of electromagnetic waves during plastic deformation ofmetals during tensile test. Frequency ranges for radiations are between 1 and 1000MHz. To investigate the hypothesis, axial turning was performed with a cutting speed190–200 (m/min) and one steel grade, SS2541 was used as a work material. Thedepth of cut and feed were set to 1 mm and 0,196 mm/rev. Detection and measurement of electromagnetic waves was performed with a spectrum analyzerMT8221B with four different signal receivers. A reference measurement was madewhen the turning machine was on without the workpiece being machined and then ameasurement was made during the turning process. The results of measurementsshowed a source of electromagnetic radiation within the frequency range 0–5 MHz.This result was achieved with copper plate as an antenna. To find out how signalsfrom acoustic emission and electromagnetic waves develop during the adhesive wearprocess, sound measurements were performed with microphones during the turningprocess. Results of sound measurement showed that the frequency at which adhesivewear occurs decreases and the amplitude increases as the insert wears. To be able toanalyze how electromagnetic radiation develops with the wear process, measurements must be performed in a shielded space from ambient disturbances, as in aworkshop there are many sources of noise that can affect the accuracy of the measurement. An antenna can be designed so that the measurement can take place asclose to the cutting zone as possible.

This bachelor’s degree project aimed to improve the wheel profile of a rail mounted trolley and determine the cause of wheel failure. The proceedings of this project where modelled after an approach for solving wear problems with an emphasis on designing for sustainability. A case study and root cause analysis (RCA) was performed and the flanged wheels were deemed insufficient for the given heavy-haul system. Possible areas of wheel profile improvement were identified and further researched with multiple literature reviews. Throughout the projects duration several limitations were introduced that reduced the concept testing to exclusively theoretical prediction models. Archard’s model was implemented to predict wear and operating time for the proposed material and wheel tread profile concepts. The wheel flange dimensions were chosen based on recommendations from wheel and rail interference handbooks among other sources. The final wheel and rail profile suggestion improved operating time by approximately 300% and wear resistance by 50% compared to its predecessor. This result was achieved by applying the same theoretical prediction model to both current and suggested profiles. The findings of this project are meant to aid SCA among others in similar cases and additionally highlight the value of product improvement from a technological, sociological, and environmental perspective.

This diploma thesis deals with measuring touches problems in industrial metrology. Thesis describes adhesive wear and tear which is caused by measuring probes when dynamical measuring is being concluded. Measuring of damaged component made of silumin and its different changes of texture by different measuring probes are evaluated. Measuring touches are made of titanium nitride, silicon nitride, zirconium, bearing chrome steel, ruby, experimental composite material and nanocrystalline diamond.