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There is currently a knowledge gap regarding the plastic material properties of many steel types that Atlas Copco use in their high torque power tools. This makes it difficult to fully utilise the capabilities of the Finite Element Method (FEM) to aid the developmental process. Case hardened steel is of special interest as there is not any established method on how to model it numerically.Test specimens of steel type 9195 and 2541 has been developed with two different geometries; hollow and solid. Specimen were heat treated to create case hardened specimens with different Case Depths (CD) as well as specimens made to mimic the material behaviour of the case and core of case hardened steel.Monotone torsion tests were conducted to generate stress-strain data for material models. Hardness tests of case hardened steel were made to determine hardness profiles. By combining these results, a spatially dependent case hardened steel material in an FE-model was created.Test results of the homogeneous specimen tests were successfully modelled using FEA. The case hardened steel could also be modelled, but with a discrepancy against the test results as the model core material were not representative actual core. However, the spatially dependent material model has high potential for simulating the case hardened steel, given the correct inputs. / Det finns för närvarnade bristfällig kännedom gällandes plastiska materialegenskaper hos många av de stål Atlas Copco använder i sina högmomentsverktyg för åtdragning av förband. Detta gör det svårt att fullt ut använda finita elementmetoden (FEM) som ett verktyg i produkters utvecklingsprocess. Sätthärdat stål är av intresse då det inte finns någon etablerad metod för hur det ska modelleras numeriskt.Provstavar gjorda av ståltyperna 9195 och 2541 har tagits fram med två olika geometrier; ihåliga och solida. Provstavarna var värmebehandlade vilket gav sätthärdade material med olika sätthärdningsdjup samt provstavar i material som skulle efterlikna materialet hos höljet och kärnan av sätthärdat stål.Monotona vridprov utfördes för att generera spännings-töjningsdata för användning i materialmodeller. Hårdhetstester gjordes för att fastställa hårdhetsprofiler hos sätthärdat stål. Genom att kombinera dessa provresultat skapades en numerisk material-model av sätthärdat stål med FEM.Testresultaten från de homogena provstavarna återskapades numeriskt med goda resultat. De sätthärdade provstavarnas beteende kunde också återskapas, men med ett något bristfälligt resultat då kärnmaterialet hos modellen inte var representativt av riktigt kärnmaterial hos sätthärdat stål. Modellen har dock hög potential för att återskapa sätthärdat stål, givet korrekt materialdata.

För att bromsa effekterna av klimatförändringarna i urbana miljöer krävs det omfattande vetenskaplig forskning inom alla områden. Till en början för att öka medvetenheten om alla oklara frågor och aspekter av effekterna av ett förändrat klimat - och sedan som ett verktyg för att skapa holistiska lösningar som bör sträva efter att lösa en sammansättning av problem inom samma insats. Med denna studie vill vi belysa vikten i sammanhållen stadsuteckling för att lyckas med klimatanpassning. Både effekter av och orsaker till urbana värmeöar är något som träder fram över längre perioder av tid, samt påverkas av permanenta och storskaliga förändringar. Argument för implementeringen av insatser såsom alternativa sätt av mobilitet blir därmed mer realistiska och genomförbara genom att belysa vikten av en mer storskalig, övergripande och gemensam planering. / To cultivate efforts to curb the effects of climate change in urban spaces, a multitude of scientific research across all features is necessary. First, as a step to raise awareness to every obscure issue and aspect of the effects of a changing climate; and second as a tool to create holistic solutions which should strive to solve a compund of issues within the same action. With this thesis we want to illustrate the importance of a cohesive urban development to be able to succeed in climate change adaption. Both effects and causes of urban heat islands appear over time and are affected by permanent and grand changes in the urban environment. Therefore, arguments for the implementation of actions such as alternative ways to confront mobility become more realistic and achievable through illustrating the importance of a more holistic and united urban planning approach.

La miniaturisation des circuits intégrés numériques tend à augmenter leur sensibilité aux radiations. Ainsi le rayonnement naturel peut induire des événements singuliers et porter atteinte à la fiabilité des circuits.Cette thèse porte sur la modélisation des mécanismes à l'origine de ces événements singuliers et sur le développement de solutions de durcissement par conception permettant de limiter l'impact des radiations sur le taux d'erreur.Dans une première partie, nous avons notamment développé une approche dénommée RWDD (Random-Walk Drift- Diffusion) modélisant le transport et la collection de charges au sein d'un circuit, sur la base d'équations physiques sans paramètre d'ajustement. Ce modèle particulaire et sa résolution numérique transitoire permettent de coupler le transport des charges avec un simulateur circuit, tenant ainsi compte de l'évolution temporelle des champs électriques dans la structure. Le modèle RWDD a été intégré avec succès dans une plateforme de simulation capable d'estimer la réponse d'un circuit suite à l'impact d'une particule ionisante.Dans une seconde partie, des solutions de durcissement permettant de limiter l'impact des radiations sur la fiabilité des circuits ont été développées. A l'échelle des cellules élémentaires, de nouvelles bascules robustes aux radiations ont été proposées, en limitant leur impact les performances. Au niveau système, une méthodologie de duplication de l'arbre d'horloge a été développée. Enfin, un flot de triplication a été conçu pour les systèmes dont la fiabilité est critique. L'ensemble de ces solutions a été implémenté en technologie 65 nm et UTBB-FDSOI 28 nm et leur efficacité vérifiée expérimentalement. / The extreme technology scaling of digital circuits leads to increase their sensitivity to ionizing radiation, whether in spatial or terrestrial environments. Natural radiation can now induce single event effects in deca-nanometer circuits and impact their reliability.This thesis focuses on the modeling of single event mechanisms and the development of hardening by design solutions that mitigate radiation threat on the circuit error rate.In a first part of this work, we have developed a physical model for both the transport and collection of radiation-induced charges in a biased circuit, derived from pure physics-based equations without any fitting parameter. This model is called Random-Walk Drift-Diffusion (RWDD). This particle-level model and its numerical transient solving allows the coupling of the charge collection process with a circuit simulator, taking into account the time variations of the electrical fields in the structure. The RWDD model is able to simulate the behavior of a circuit following a radiation impact, independently of the implemented function and the considered technology.In a second part of our work, hardening solutions that limit radiation impacts on circuit reliability have been developed. At elementary cell level, new radiation-hardened latch architectures have been proposed, with a limited impact on performances. At system level, a clock tree duplication methodology has been proposed, leaning on specific latches. Finally, a triplication flow has been design for critical applications. All these solutions have been implemented in 65 nm and UTBB-FDSOI 28nm technologies and radiation test have been performed to measure their hardening efficiency.

Este trabalho tem a intenção de contribuir com informações sobre a integridade superficial resultante do processo de torneamento em material endurecido de componentes mecânicos fabricados em aço cementado ABNT 8620 (DIN 21 NiCrMo 2). A análise das tensões residuais do corpo de prova foi experimentalmente conduzida pelo Método do Furo Cego Incremental, no qual um pequeno furo é introduzido na superfície do componente e a deformação aliviada é registrada por meio de extensômetros especiais, e também, pelo método da difração de raios-X. A superfície foi analisada através de parâmetros obtidos do mapeamento tridimensional da topografia superficial com instrumento de interferometria laser. Os parâmetros de rugosidade, selecionados para medição, visaram uma caracterização funcional das superfícies obtidas, tais como capacidade de carga, capacidade de retenção de fluidos lubrificantes e resistência ao desgaste. Também foram executados ensaios metalográficos para avaliar a existência de camadas de material alteradas abaixo da superfície. Os resultados indicaram que o torneamento em material endurecido foi capaz de produzir uma superfície resultante com boa área de contato, boa capacidade de carregamento e razoável capacidade de retenção de fluidos uma vez que nem todos os parâmetros se encontraram na faixa funcional ideal. O torneamento em material endurecido induziu tensão de compressão nas camadas das amostras cementadas, cuja condição original era tensão residual de tração. Não foram detectadas alterações expressivas na camada cementada, principalmente na região limítrofe da área transversal com a superfície devido ao aquecimento e rápido resfriamento imposto pelo processo de usinagem. / The aim of the present work is to provide relevant information regarding the obtained surface integrity during hard turning process of mechanical components manufactured from case hardened steel ABNT 8620 (DIN 21 NiCrMo 2). The sample residual stress analysis has been experimentally conducted by the incremental Blind Hole method, in which a small hole is machined on the surface of the component and the relieved deformation is recorded through special strain gages, and by the X-ray diffraction technique. The surface was examined by parameters obtained from the surface topography three-dimensional mapping with a laser interferometer instrument. The selected roughness parameters analysis intends to have a functional characterization such as bearing capacity, fluid and lubricants retention ability and contact wear resistance. In the search for altered material layers beneath the surface, metallographic studies were carried out. The functional bearing area curve analysis parameters indicated that the resulting surface has a good area contact, good bearing capacity and reasonable ability to fluid retention as the reduced valley depth parameter did not produced negative values for all conditions tested. The hard turnig process was able to add compression residual stress condition at the surface, and no significant changes were found at the case hardened layer due to rapid heating and cooling imposed by the hard turning process.

Les Bétons Fibrés Ultra Performants (BFUP) sont les matériaux cimentaires aux performances les plus exceptionnelles. Ils se distinguent par des résistances caractéristiques à 28 jours en compression et en traction supérieures respectivement à 150 MPa et 6 MPa. Dans une politique globale de gestion économique et d'impact écologique de l'entreprise Lagarrigue, l'utilisation de BFUP en substitution des bétons de classe de résistance ordinaire en préfabrication parait pertinente. Cependant, les formulations actuelles onéreuses et peu écologiques limitent leur utilisation et leur essor. Cette étude a pour but de proposer des formulations de BFUP industrialisables caractérisées par un meilleur bilan économique et écologique, et conformes aux exigences de la prénorme matériaux BFUP (PR NF P18-470). Suite à une première étude de formulation et d'optimisation, quatre compositions de BFUP ont été mises au point sans traitement thermique, trois à base de métakaolin et une de référence plus classique avec fumée de silice. Leur caractérisation à l'état frais et à l'état durci a ensuite été réalisée afin de dresser leurs cartes d'identité et de les situer de manière réglementaire selon la prénorme (PR NF P18-470). Les bétons formulés sont autoplaçants et thixotropes. Le caractère thixotrope pouvant causer une discontinuité de l'interface entre deux couches de béton lors du coulage, des recommandations vis-à-vis du phasage de fabrication et de bétonnage ont été proposées. A l'état durci, un BFUP avec métakaolin et celui équivalent avec fumée de silice atteignent des résistances en compression supérieures à 150 MPa permettant de les classer en BFUP-S utilisables pour les structures alors que les deux autres formules à base de métakaolin dépassant les 130 MPa sont classés en BFUP-Z non structuraux (PR NF P18-470). En traction, trois BFUP sont de classe T2, leurs résistances élastiques et de post-fissuration sont respectivement comprises entre 6,0 et 8,0 MPa, et entre 4,6 et 7,0 MPa, une dernière composition étant à la limite de classification avec une résistance élastique et post-fissuration de 5,9 et 4,0 MPa respectivement. Les valeurs limites de retrait et du coefficient de fluage de la prénorme (PR NF P18-470) sont respectées. L'étude de la microstructure a permis de conforter certaines hypothèses émises lors de la caractérisation mécanique, notamment le retrait et le fluage. L'étude des propriétés de transfert montre une durabilité potentielle très élevée. La dernière phase constitue un aboutissement de ce projet avec la première application industrielle, basée sur le dimensionnement selon la future norme de calcul BFUP (PR-NF P18-710), qui concerne la réalisation d'éléments préfabriqués d'un ouvrage. / Ultra-High Performance Fiber-Reinforced Concretes are cementitious materials of exceptional performances. They are characterized by a compressive and tensile strength over respectively 150 MPa and 6 MPa at 28 days. Within a global management of economic and the environmental impact of Lagarrigue company, the use of UHPFRC in substitution of ordinary concrete in precast elements seems relevant. However, expensive materials and environmental cost of current mix design restrict their use and development. This study aims at proposing UHPFRC mix designs which are characterized by better economic and environmental cost and respect criteria of the pre-standard UHPFRC materials (PR NF P18-470). Firstly, an optimization study of UHPFRC mix design has been established, four mixtures have been developed without heat treatment application, three of them based on metakaolin and one with silica fume as a reference mixture. Secondly, the characterization of fresh and hardened state was conducted in order to establish their identity cards and confront them to the criteria of (PR NF P18-470. In the fresh state, all concretes studied are self-compacting concretes and present thixotropic character. The thixotropic character may cause a discontinuity of the interface between two layers of concrete during casting, recommendations of manufacturing and casting process have been proposed. In the hardened state, one UHPFRC with metakaolin and another one with silica fume reached compressive strengths over 150 MPa, they could be classified as UHPFRC-S and could be used for structures designs while the two other mixtures based on metakaolin exceeded 130 MPa were classified as non-structural UHPFRC-Z (PR NF P18-470). For tensile behavior, three UHPFRC are classed T2, their elastic and post-cracking strengths are between 6.0 and 8.0 MPa, and between 4.6 and 7.0 MPa respectively, while the last mixture is in the classification limit with elastic and post-cracking strengths of 5.9 and 4.0 MPa respectively. The limit values of shrinkage and creep coefficient recommended (PR NF P18-470) were satisfying. The microstructure evaluation allowed strengthening certain assumptions made in the mechanical characterization, including shrinkage and creep. The durability characterization showed very high potential sustainability materials. The last part is an outcome of this research project with the first industrial application, based on the structural design of the UHPFRC future standard (PR NF-P18-710) which concerns the realization of precast elements of a structure.

Este trabalho tem a intenção de contribuir com informações sobre a integridade superficial resultante do processo de torneamento em material endurecido de componentes mecânicos fabricados em aço cementado ABNT 8620 (DIN 21 NiCrMo 2). A análise das tensões residuais do corpo de prova foi experimentalmente conduzida pelo Método do Furo Cego Incremental, no qual um pequeno furo é introduzido na superfície do componente e a deformação aliviada é registrada por meio de extensômetros especiais, e também, pelo método da difração de raios-X. A superfície foi analisada através de parâmetros obtidos do mapeamento tridimensional da topografia superficial com instrumento de interferometria laser. Os parâmetros de rugosidade, selecionados para medição, visaram uma caracterização funcional das superfícies obtidas, tais como capacidade de carga, capacidade de retenção de fluidos lubrificantes e resistência ao desgaste. Também foram executados ensaios metalográficos para avaliar a existência de camadas de material alteradas abaixo da superfície. Os resultados indicaram que o torneamento em material endurecido foi capaz de produzir uma superfície resultante com boa área de contato, boa capacidade de carregamento e razoável capacidade de retenção de fluidos uma vez que nem todos os parâmetros se encontraram na faixa funcional ideal. O torneamento em material endurecido induziu tensão de compressão nas camadas das amostras cementadas, cuja condição original era tensão residual de tração. Não foram detectadas alterações expressivas na camada cementada, principalmente na região limítrofe da área transversal com a superfície devido ao aquecimento e rápido resfriamento imposto pelo processo de usinagem. / The aim of the present work is to provide relevant information regarding the obtained surface integrity during hard turning process of mechanical components manufactured from case hardened steel ABNT 8620 (DIN 21 NiCrMo 2). The sample residual stress analysis has been experimentally conducted by the incremental Blind Hole method, in which a small hole is machined on the surface of the component and the relieved deformation is recorded through special strain gages, and by the X-ray diffraction technique. The surface was examined by parameters obtained from the surface topography three-dimensional mapping with a laser interferometer instrument. The selected roughness parameters analysis intends to have a functional characterization such as bearing capacity, fluid and lubricants retention ability and contact wear resistance. In the search for altered material layers beneath the surface, metallographic studies were carried out. The functional bearing area curve analysis parameters indicated that the resulting surface has a good area contact, good bearing capacity and reasonable ability to fluid retention as the reduced valley depth parameter did not produced negative values for all conditions tested. The hard turnig process was able to add compression residual stress condition at the surface, and no significant changes were found at the case hardened layer due to rapid heating and cooling imposed by the hard turning process.

Orientador: Anselmo Eduardo Diniz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-05T19:57:39Z (GMT). No. of bitstreams: 1 Pivetta_CarlosSergio_M.pdf: 2572259 bytes, checksum: d75f09a259545ac56a46ecc1d5870ba0 (MD5) Previous issue date: 2005 / Resumo: O fresamento de cavidades de moldes e matrizes em material endurecido usando ferramenta de topo esférico tem limitações em termos de profundidades das cavidades, da taxa de remoção de cavaco e da vida da ferramenta. Algumas operações de fresamento em cavidades profundas não podem ser realizadas, devido à necessidade de se ter ferramenta com alto balanço, o que gera vibração e, em conseqüência, danos à rugosidade da peça e à vida da ferramenta. Outro ponto ainda não totalmente compreendido é a influência da rugosidade deixada na peça pela operação anterior, na rugosidade da operação de acabamento, já que, devido às baixas profundidades utilizadas nesta operação, a rugosidade da operação anterior pode influenciar a profundidade real removida. O principal objetivo deste trabalho é verificar a influência da relação comprimento/diâmetro da ferramenta (balanço), da rugosidade da operação anterior e da velocidade de corte na rugosidade da peça e na vida da ferramenta de fresamento em acabamento. Para isto foram realizados ensaios de fresamento em aço endurecido AISI D2 (58 HRC) com ferramenta de ponta esférica de metal duro recoberto, variando-se os citados parâmetros de influência. Dentre as conclusões deste trabalho, pode-se destacar: nem a rugosidade da operação anterior, nem o balanço da ferramenta influenciaram a rugosidade da peça, pelo menos nos níveis utilizados neste trabalho; com balanço da ferramenta pequeno, consegue-se baixos valores de desgaste e, com isso, longa vida da ferramenta, mas quando se utiliza conjuntamente balanço da ferramenta e velocidades de corte altas, a vida da ferramenta é bastante reduzida / Abstract: The milling of molds and dies cavities carried out on hardened steel using ball end mill presents limitations in terms of cavity depth, metal removal rates and tool life. Some milling operations on deep cavities are not possible due to the require of long tool overhang, what generates vibrations and, consequently, resulted in poor surface roughness and short tool life. Other point which is not totally understood up to the present is the influence of the surface roughness obtained in the previous operation on the results of finishing operation because on finishing operations, the actual depth of cut is not much larger than the height of roughness left on the surface by the previous operation. The main objective of this work is to verify the influence of the ratio tool overhang/ tool diameter, the roughness of the previous operation and cutting speed on the tool wear in finishing operations. Besides, it also intends to verify the influence of tool wear on the tool vibration, measured through the real time tool deflection. Milling experiments on AISI D2 hardened steel (58 HRC) were carried out using coated (TiNAl) carbide ball end mills with the input variables already mentioned. The main conclusions of this experiments, for the used conditions, were: the previous surface roughness neither the tool overhang have influence on the resulting surface roughness; when the tool overhang was the lowest one, cutting speed did not influence so much tool wear, but when the highest tool overhang was used, cutting speed presented a strong influence on tool wear / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

A reação álcali-agregado - RAA é uma patologia de ação lenta que tem sido observada em construções de concreto capaz de comprometer suas estruturas. Sabe-se que a reação álcali-agregado é um fenômeno bastante complexo em virtude da grande variedade de rochas na natureza que são empregadas como agregados no preparo do concreto, podendo cada mineral utilizado afetar de forma distinta a reação ocorrida. Em função dos tipos de estrutura, das suas condições de exposição e dos materiais empregados, a RAA não se comporta sempre da mesma forma, em virtude disto a pesquisa constante neste tema é necessária para o meio técnico e a sociedade. Pesquisas laboratoriais, empíricas e experimentais tem sido rotina em muitos dos estudos da RAA dada ainda à carência de certas definições mais precisas a respeito dos métodos de ensaio, mas também em função da necessidade do melhor conhecimento dos materiais de uso em concretos como os agregados, cimentos, adições, aditivos entre outros e do comportamento da estrutura. Embora técnicas de prevenção possam reduzir significativamente a incidência da RAA, muitas estruturas foram construídas antes que tais medidas fossem conhecidas, havendo no Brasil vários casos de estruturas afetadas, sendo custosos os reparos dessas estruturas. Em estudos recentes sobre o tamanho das partículas de álcali-agregado e sua distribuição foi concluído que o tamanho do agregado está relacionado com o potencial danoso da RAA. Existem ainda indícios de que o tamanho e a distribuição dos poros do concreto também sejam capazes de influenciar o potencial reativo do concreto. Neste trabalho desenvolvemos um Sistema de Visão Artificial (SVA) que, com o uso de técnicas de Processamento de Imagens, é capaz de identificar em imagens de concreto, agregado e poros que atendam em sua forma, às especificações do usuário, possibilitando o cálculo da porosidade e produzindo imagens segmentadas à partir das quais será possível extrair dados relativos à geometria desses elementos. Serão feitas duas abordagens para a obtenção das imagens, uma por Escâner Comercial, que possui vantagens relacionadas à facilidade de aquisição do equipamento, e outra por micro tomógrafo. Uma vez obtidas informações sobre as amostras de concreto, estas podem ser utilizadas para pesquisar a RAA, comparar estruturas de risco com estruturas antigas de forma a melhorar a previsão de risco de ocorrência, bem como serem aplicadas a outras no estudo de outras patologias do concreto menos comuns no nosso país, como o efeito gelo/degelo. / The alkali-aggregate reaction - RAA is a condition of slow action that has been observed in concrete constructions that could affect their structures. It is known that the alkali-aggregate reaction is a very complex phenomenon because of the great variety of rocks in nature that are used as aggregates for concrete, and each mineral used differently affects the reaction occurred. Depending on the type of structure, its exposure conditions and the materials used, this phenomenon does not always behaves the same way, because of this, constant research in this area is needed for the technical means and the society. Laboratory, empirical and experimental research has been routine in many of the RAA studies still given the lack of certain more precise definitions concerning the testing methods, but also because of the need for better understanding of the use of materials in concrete as aggregate, cement, additions, additives etc. and structure behavior. Prevention techniques could significantly reduce the incidence of RAA. Still, many structures were built before such measures were known, several cases of affected structures were discovered in Brazil, all with large spending on repairs of the affected structures. In recent studies on the particle size of the alkaliaggregate and its distribution was concluded that the aggregate size is related to the damaging potential of the RAA. There are also indications that the size and distribution of concrete pores are also capable of influencing the reactive potential of the concrete. In the present work we developed an Artificial Vision System ( VAS ) that uses image processing techniques to identify aggregate and pores in hardened concrete images, enabling the calculation of porosity and producing segmented images that can be used to investigate data about the geometry of these elements. Were made two approaches for obtaining the images, one by Scanner Commercial, which has related advantages will ease the acquisition of equipment, and other micro CT scanner. Once obtained information on the concrete samples, these can be used to search the AAR compared risk structures with old structures so as to enhance the occurrence of risk prediction, as well as be applied to other concrete in the study of other pathologies less common in our country, as ice effect / thaw.

The use of pre-hardened mold steels has increased appreciably over the years; more than 80% of the plastic mold steels are used in pre-hardened condition. These steels are delivered to the customer in finished state i.e. there is no need of any post treatment. With hardness around ~40HRC, they have properties such as good polishability, good weldability, corrosion resistance and thermal conductivity. Machinability is a very important parameter in pre-hardened mold steels as it has a direct impact on the cost of the mold. In normal machining operations involving intricate or near net shapes, machining constitutes around 60% of the total mold cost. Efforts are underway to explore every possible way to reduce costs associated with machining and to make production more economical. All the possible parameters which are considered to affect the machinability are being investigated by the researchers. This thesis work focuses on the effect of prior austenite grain size on the machinability of pre-hardened mold steel (Uddeholm Nimax).  Austenitizing temperatures and holding times were varied to obtain varying grain sized microstructures in different samples of the same material. As it was difficult to delineate prior-austenite grain boundaries, experimental and empirical methods were employed to obtain reference values. These different grain sized samples were thereafter subjected to machining tests, using two sets of cutting parameters. Maximum flank wear depth=0.2mm was defined for one series of test which were more akin to rough machining, and machining length of 43200mm or maximum wear depth=0.2mm were defined for second series of tests which were similar to finishing machining. The results were obtained after careful quantative and qualitative analysis of cutting tools. The results obtained for Uddeholm Nimax seemed to indicate that larger grain sized material was easier to machine. However, factors such as retained austenite content and work hardening on machined surface, which lead to degradation of machining operations were also taken into consideration. Uddeholm Nimax showed better machinability in large grained samples as retained austenite(less than 2%) content was minimal in the large grained sample. Small grained sample in Uddeholm Nimax had a higher retained austenite (7+2%) which resulted in degradation of machining operation and a lesser cutting tool life.