В работе проведен обзор основных технологий производства холоднокатаных листов низкоуглеродистых сталей для изготовления изделий методом холодной штамповки и эмалирования. Проанализированы химические составы, структура, кристаллографическая текстура образцов листов, и их влияние на возможности производства бытовых изделий (ванн, моек, поддонов). Рассмотрены вопросы улучшения качества листов низкоуглеродистых сталей, используемых для холодной штамповки и эмалирования. / The paper reviews the main technologies to produce cold-rolled sheets of low-carbon steels for the manufacture of products by cold stamping and enameling. The chemical compositions, structure, crystallographic texture of sheet samples, and their influence on the possibility of manufacturing household products (bathtubs, sinks, and pallets) are analyzed. The issues of improving the quality of low-carbon steel sheets used for cold stamping and enameling are considered.

Application of clean and ultraclean steels have shown to provide favourable mechanical properties for bearings and transmission components, specifically regarding fatigue performance, compared to conventional steel grades. Clean steels are characterized by containing a very low level of non-metallic inclusions. While this characteristic is beneficial for the fatigue strength, inclusions in steels have shown to be favorable for the machinability and therefore challenges during machining of clean steels can arise. In this thesis the machinability and tool wear mechanisms of ultraclean steel have been evaluated during longitudinal turning. The aim of the study was to determine how steel cleanness and inclusions impact different machinability aspects. This was achieved by performing a comparative study of three steel grades with different level of cleanness and inclusions characteristics. Four machining experiments were executed investigating the chip breakability, cutting force, tool life and cutting tool coating degradation. The machined inserts were then analysed using light optical microscopy, secondary electron microscopy and electron probe microanalysis. The result revealed that the ultraclean steel grade has the overall worst machinability with the lowest chip breakability, highest cutting forces, and lowest tool life for the investigated steels. Additionally, it was found that the inserts that machined the ultraclean steel and the calcium treated steel was exposed to severe crater wear. However, the coating degradation causing the crater wear differs between the two grades. For the ultraclean steel the wear rate of the entire chemical vapor deposition coating is high. In contrast, for the calcium treated steel only the top alumina layer degrades rapidly and the underlying titanium carbonitride layer have a low wear rate. / Användning av rena och ultrarena stål har visat sig ge gynnsamma mekaniska egenskaper för kullager och transmissionskomponenter, speciellt gällande utmattningsprestanda, jämfört med konventionella stålsorter. Rena stål kännetecknas av att de innehåller en mycket låg nivå av icke-metalliska inneslutningar. Denna egenskap är fördelaktig för utmattningshållfastheten, men däremot har inneslutningar i stål visat sig vara gynnsamma för bearbetbarheten och därför kan utmaningar uppstå vid bearbetning av rena stål. I detta arbete har bearbetbarheten och verktygsslitagemekanismerna för ultrarent stål utvärderats under längsgående svarvning. Syftet med studien var att fastställa hur stålets renhet och inneslutningar påverkar olika bearbetningsaspekter. Detta uppnåddes genom att utföra en jämförande studie av tre stålsorter med olika renhetsgrad samt inneslutningar. Fyra bearbetningsexperiment utfördes för att undersöka spånbrytbarheten, skärkraften, verktygets livslängd och nerbrytningen av skärverktygets beläggning. De bearbetade skären analyserades sedan med användning av ljusoptisk mikroskopi, svepelektronmikroskopi och elektronprobmikroanalys. Resultatet visade att den ultrarena stålsorten har den totalt sett sämsta bearbetbarheten med lägst spånbrytbarhet, högsta skärkrafter och lägsta verktygslivslängd av de undersökta stålen. Dessutom upptäcktes att skären som bearbetade det ultrarena stålet och det kalciumbehandlade stålet utsattes för kraftigt kraterslitage. Nedbrytningen av verktygs beläggningen som orsakar kraternötningen skiljer sig dock mellan de två stålkvaliteterna. För det ultrarena stålet är slitagehastigheten för hela beläggningen hög. För det kalciumbehandlade stålet bryts däremot endast det övre aluminiumoxidskiktet ned snabbt och det underliggande titankarbonitridskiktet har en låg nötningshastighet.

<p dir="ltr">In structural metallic components, a material’s lifecycle begins with the processing route, to produce a desired structure, which dictates the in-service performance. The variability of microstructural features as a consequence of the processing route has a direct influence on the properties and performance of a material. In order to correlate the influence processing conditions have on material performance, large test matrices are required which tend to be time consuming and expensive. An alternative route to avoid such large test matrices is to incorporate physics-based process modeling and lifing paradigms to better understand the performance of structural materials. By linking microstructural information to the material’s lifecycle, the processing path can be modified without the need to repeat large-scale testing requirements. Additionally, when a materials system is accurately modeled throughout its lifecycle, the performance predictions can be leveraged to improve the design of materials and components.</p><p dir="ltr">Ni-based superalloys are a material class widely used in many critical aerospace components exposed to coupling thermal and mechanical loads due to their increased resistance to creep, corrosion, oxidation, and strength characteristics at elevated temperatures. Many Ni-based superalloys undergo high-temperature forging to produce a desired microstructure, targeting specific strength and fatigue properties in order to perform under thermo-mechanical loads. When in-service, these alloys tend to fail as a consequence of thermo-mechanical fatigue (TMF) from either inclusion- or matrix- driven failure. In order to produce safer, cheaper and more efficient critical aerospace components, the micromechanical deformation and damage mechanisms throughout a Ni-based superalloy’s lifecycle must be understood. This research utilizes process modeling as a tool to understand the damage and deformation of inclusions in a Ni-200 matrix throughout radial forging as a means to optimize the processing conditions for improved fatigue performance. In addition, microstructural sensitive performance modeling for a Ni-based superalloy is leveraged to understand the influence TMF has on damage mechanisms.</p><p dir="ltr">The radial forging processing route requires both high temperatures and large plastic deformation. During this process, non-metallic inclusions (NMIs) can debond from the metallic matrix and break apart, resulting in a linear array of smaller inclusions, known as stringers. The evolution of NMIs into stringers can result in matrix load shedding, localized plasticity, and stress concentrations near the matrix-NMI interface. Due to these factors, stringers can be detrimental to the fatigue life of the final forged component. By performing a finite element model of the forging process with cohesive zones to simulate material debonding, this research contributes to the understanding of processing induced deformation and damage sequences on the onset of stringer formation for Alumina NMIs in a Ni-200 matrix. Through a parametric study, the interactions of forging temperature, strain rate, strain per pass, and interfacial decohesion on the NMI damage evolution metrics are studied, specifically NMI particle separation, rotation, and cavity formation. The parametric study provides a linkage between the various processing conditions parameters influence on detrimental NMI morphology related to material performance.</p><p dir="ltr">The microstructural characteristics of Ni-based superalloys, as a consequence of a particular processing route, creates a variability in TMF performance. The micromechanical failure mechanisms associated with TMF are dependent on various loading parameters, such as temperature, strain range, and strain-temperature phasing. Insights on the complexities of micromechanical TMF damage are studied via a temperature-dependent, dislocation density-based crystal plasticity finite element (CPFE) model with uncertainty quantification. The capabilities of the model’s temperature dependency are examined via direct instantiation and comparison to a high-energy X-ray diffraction microscopy (HEDM) experiment under coupled thermal and mechanical loads. Unique loading states throughout the experiment are investigated with both CPFE predictions and HEDM results to study early indicators of TMF damage mechanisms at the grain scale. The mesoscale validation of the CPFE model to HEDM experimental data provides capabilities for a well-informed TMF performance paradigm under various strain-temperature phase profiles. </p><p dir="ltr">A material’s TMF performance is highly dependent on the temperature-load phase profile as a consequence of path-dependent thermo-mechanical plasticity. To investigate the relationship between microstructural damage and TMF phasing effects, the aforementioned CPFE model investigates in-phase (IP) TMF, out-of-phase (OP) TMF, and iso-thermal (ISO) loading profiles. A microstructural sensitive performance modeling framework with capabilities to isolate phasing (IP, OP, and ISO) effects is presented to locate fatigue damage in a set of statistically equivalent microstructures (SEMs). Location specific plasticity, and grain interactions are studied under the various phasing profiles providing a connection between microstructural material damage and TMF performance.</p>