Over time the level of inoculant will decrease due to fading and this needs to be compensated bymore additions of inoculant. When casting CGI400 at Scania a one-step method is used, and the inoculant additions are based on the last ladle from the previous oven. Longer stops in production will result in the previous oven not being representable and more inoculant should be added. A method to establish the inoculation level of the base iron in the oven would make it easier to control the process. This study was about inoculation measurements with the help of thermo- analysis of the melt in the oven to get a better understanding how it fluctuates between ovens and changes over time. The study is also about how to implement this tool into production in a foundry. With the help of thermo- analytic measurements, the inoculation level of the melt was established, and the method was also used to see how the level of inoculant changed over. To establish the inoculation additions needed, the saturation point of inoculant was investigated. The results from the study shows that the starting level of inoculant is too low in the melt it also shows that the inoculation level fluctuates over time. The conclusions that can be drawn from this study is that thermos analysis can be used in production to establish the inoculation level, but moremeasurements needs to be conducted to determine its accuracy. / Över tid så minskar ympnivån i en smälta på grund av fading och detta måste kompenseras med mertillsatser av ymp. Vid gjutning av CGI400 på Scania används en en-stegs metod där man baserar ymptillsatsen i skänken på vad ympnivån var i sista skänken från den tidigare ugnen. Vid längre produktionsstopp kommer inte ympnivån från ugnen innan vara representativ utan mer ymp måste tillsättas. En metod för att bestämma ympnivån av basjärnet i ugnen skulle göra det lättare att styra processen. Denna studie handlar om ympmätning med hjälp av termisk analys i bas smälta för att få en bättre förståelse för hur den fluktuerar mellan ugnar och ändras över tid. Studien handlar också om hur man ska kunna applicera denna mätmetod i produktionen på ett gjuteri. Med hjälp av termo analytiska mätningar skulle grundnivån av ymp i smältan bestämmas och även för att se hur nivån ändrades över tiden. För att bestämma tillsatsen av ymp som borde tillföras undersöktes mättnadspunkten av ymp och hur den kunde tillsättas i skänk. Resultaten från studien visar att grundnivån av ymp är för låg och resultaten visar också att nivån av ymp fluktuerar både upp och ner ökar tid vilket inte var vad man hade förväntat sig och även det finns flera faktorer som kan påverka nivån. Slutsatsen som kan dras är att termisk analys kan användas i produktion för att bestämma ympnivån, men mer mätningar behövs för att bestämmadess noggrannhet.

Lamellar cast iron is a very important technical alloy and the most used material in the casting production, and especially in the automotive industry which is the major consumer. Beside the many great properties, it is inclined to form casting defects of which some can be prevented, and some may be repaired subsequently. Shrinkage porosity is a randomly returning problem, which is difficult to understand and to avoid. This defect is a volumetric deficiency which appear as cavities inside the casting in connection to the casting surface. Another frequent defect is the metal expansion penetration. This defect is a material surplus squeezed to the casting surface containing sand inclusion from the mold material. Shrinkage porosity is usually mentioned together with metal expansion penetration as the formation mechanism of both defects have common roots. It is also generally agreed, that these type of defects are related to the volumetric changes occurring during solidification. Additionally, the formation of these defects are in connection with the coherency of the primary austenite dendrites. The purpose of this work was to develop knowledge on factors affecting a volume-change related casting defect formation in order to minimize the presence of these defects in engine component production. This was done by extending the existing solidification investigation methods with novel solutions. Introduction of expansion force measurement in the determination of dendrite coherency combined with multi axial volume change measurement refine the interpretation of the solidification. Comparison of registered axial and radial linear deformation in cylindrical samples indicated an anisotropic volume change. Different methods for dendrite coherency determination have been compared. It was shown that the coherency develops over an interval. Dependent on the added inoculant the coherency is reached at different levels of fractions of a solidified primary phase. It is also shown, that inoculation has an effect on the nucleation and growth of the primary phase. Quantitative image analysis has been performed on the primary phase in special designed samples designed to provoke shrinkage porosity and metal expansion penetration. It was found, that the inter-dendritic space varies within a casting. This was explained by the coarsening of the primary dendrites which originates from differences in the local time of solidification. / <p>QC 20131210</p>

An exhaust manifold of a truck engine is subjected to tough conditions. As the truck is started, operated and shut down, it becomes subjected to thermal cycling up to around 800°C. At such high temperatures, corrosion, fatigue and creep are active degradation mechanisms. As can be imagined, the interplay between the three complicates materials selection. It is desired to have a versatile grade of high durability which is not too expensive. At the moment, a ferritic, ductile cast iron designated SiMo51 is used for the application. However, due to the rough conditions, it is considered to be on the verge of its operational limit. As a consequence, there is an ongoing search for candidate materials. In this study, the ductile cast irons SiMo51, SiMo1000, D5S and the cast steel HK30 have been included. In the past, there have been several studies describing corrosion and fatigue of the cast materials used for exhaust manifolds. However, on the subject of creep of cast materials, little is known. The present study aims to reveal creep tendencies of cast materials and to do it in several ways. More precisely, three creep-testing methods were employed: the conventional constant-load creep-test, the “Sequential tensile test (STT)” and “Stress relaxations with thermal cycling (SRTC)”. The first one is the traditional one. It is tedious, usually lasting months or years. The second one is a tensile test in which the strain rate is changed in sequences as specimen deformation proceeds. Here, the idea is that a slow tensile test is not different from a conventional creep test. In the third one, stress relaxations are provoked as a specimen is thermally cycled in a locked state. Since stress relaxations are a consequence of creep deformation, the relaxation data gathered from isothermal holds can be directly compared to results from the isothermal constant-load creep-test and STT. When thermally cycled in a locked state, the materials display a loop character in σ, ε and T which provides extensive information about the mechanical properties over the selected temperature interval. In a logarithmic Norton plot, the creep strain rate is plotted as a function of stress. By plotting STT-data in such Norton plots, it was shown that the creep behaviour of the included materials is well represented by Norton’s law. Furthermore, it was found that the creep strain rates and stress relaxations, measured during isothermal holds in SRTC, in several cases show perfect coincidence with tensile test data obtained through STT. At 700°C, data from all three tests were inserted in the same Norton plot. At higher stress levels, the SRTC-curve follows the STT-curve and at lower stresses, when the creep regime is entered, it bends down and unites with data obtained by the constant-load creep tests. Additionally, it was seen that a relatively high degree of pre-deformation can give a critical stress below which creep deformation stops completely. / <p>The Financier is Scania CV. </p>

The master‘s thesis deals with the influence of the thermal cycle of welding with preheat on castings made of grey cast iron to change the hardness. The thesis deals with the classification of graphitic cast irons, their structure, properties and influences they have on the formation and transformation of the structure. Emphasis is placed on chemical composition and structure stability at elevated temperatures. The practical part deals with the investigation of the effects of casting repair on the decrease of hardness measured in the foundry Heunisch Brno.

The blast furnace process for the reduction of iron ore to pig iron faces problems such as emission of air pollutants, high investment cost and the current major problem of decreasing supplies of coke. Coke is used in large quantities to promote a combination of direct and indirect reduction within the furnace. Due to the lack of good coking coal within South Africa, and dwindling supplies worldwide, new iron-making processes, are being developed using coal and/or natural gas to replace coke as the reductant. The new processes allow efficient use of carbon, fed in the form of coal pellets (coalbased processes) or natural gas (gas-based processes), as the reducing agent. Presently, most coal-based processes Use an excess of coal, up to 500% stoichoimetric addition, and are run at temperatures up to ±1200°C, although reduction tends to proceed at ±850°C. This project developed a low temperature process using mixed pellets of fine waste iron oxide and fine domestic coal with a natural carbonaceous binder (a by-product from local pulping industry). Reduction tests performed on composite pellets in a tube furnace and thermobalance indicated, upon analysis by X-Ray Diffraction and Scanning Electron Microscope, that reduction occurred gradually at 900°C. Implementing induction heating of bulk pellets reduced heating times substantially. Induction heating also resulted in direct reduced iron [DRI] containing 75 - 80% metallic iron. Energy consumption based on coal usage amounted to 23.71 GJ/ton DRI, which compares with the calorific consumption of most coal-based processes, i.e. coal consumption range between 15 and 25 GJ/ton DRI. Energy consumed during induction heating amounted to 9.94 GJ/ton DRI, as electricity. This energy consumption value does not take into account the efficiency of the primary energy required to generate electricity. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2003.

Este estudo apresenta uma abordagem para a avaliação do comportamento de um ferro fundido branco de alto cromo e um aço ferramenta AISI D2 submetido a ciclos térmicos. Para a realização do estudo foi desenvolvido um procedimento para ensaios de fadiga térmica submetidos a números de ciclos variados, usando para aquecimento um sistema indutivo e para resfriamento um tanque de água. Devido a complexidade dos fenômenos envolvidos, um modelo de elementos finitos foi elaborado para a solução do campo de temperaturas e tensões superficiais atuantes. O controle da tensão superficial atuante foi realizado por meio da mudança de geometria do corpo de prova, sendo esta geometria resultante de teste por simulação computacional. Os corpos de prova foram caracterizados quando a sua microdureza e fração volumétrica de carbonetos antes do ensaio e após ensaio foram caracterizados quanto a sua microdureza, número e profundidade das trincas. O regime de propagação durante os primeiros 50 ciclos foi controlado por mecanismo de fadiga de baixo ciclo, exibindo as maiores velocidade de propagação das trincas e o regime de propagação depois dos 50 ciclos foram controlados por mecanismos de fadiga de alto ciclo. A nucleação das trincas ocorreu predominantemente pela interface matriz/carboneto e pelo próprio carboneto, sendo a propagação das trincas predominantemente pela interconexão de carbonetos fraturados na superfície do material e predominantemente na interface matriz carboneto em camadas mais profundas do corpo de prova. Os resultados obtidos mostraram uma boa correlação entre o ensaio e o modelo numérico, permitindo uma maior confiabilidade para execução do modelo mecânico subsequente. Baseado nos resultados foi possível propor uma metodologia para a avaliação de ambos materiais submetidos a ciclos térmicos. / This study presents an approach to evaluate the behavior of high chromium white cast iron and AISI D2 tool steel submitted at thermal cycles. It was developed a procedure for a thermal fatigue test in different times of cycles were done, using induced heating and water cooling. Due to the complexity of the phenomena involved, a FEM study was performed for solving the temperatures and superficial stresses fields. The control of superficial stress was done by changing the geometry of the test specimens, what was defined by computational simulation. The test specimens were evaluated the microstructure, microhardness and carbides contends before the test. After the test were evaluated microhardness, amount and depth of thermal fatigue cracks. The propagation during the earlier cycles was defined by mechanics of low cycle instead of after 100 cycles that was defined by mechanics of high cycle fatigue. This mechanics was observed by crack velocity analyses in both periods. The nucleation of thermal fatigue cracks initiate mostly at the matrix/carbide interface or at the carbide itself, being the cracks propagation was mainly by the interconnection of fractured carbides at surface and mainly at the interface matrix/carbide in the inner layer of the specimens test. The results obtained showed an adherence between the test and the numerical model, allowed a greater reliability to the subsequent mechanical model. Based on the results was possible propose a methodology for evaluation of both materials subjected a thermal cycles.

Nos dias atuais, com o mercado altamente seletivo, com vários fabricantes e fornecedores de diversos tipos de produtos e serviços, a qualidade se tornou uma necessidade premente, na qual uma empresa que forneça bens e/ou serviços com baixa qualidade corre sérios riscos de ser descartada pelos mercados consumidores. Assim, a importância da qualidade é que se converteu em um requisito básico para uma empresa competir e se manter no mercado. As empresas veem a qualidade como uma ferramenta para a redução de custos e para a melhoria de sua imagem junto ao mercado consumidor. Neste contexto, de melhora da imagem junto ao mercado consumidor e de redução de custos, o presente trabalho foi realizado em uma importante e tradicional multinacional de grande porte que produz compressores herméticos para refrigeração, com o intuito de estudar a soldagem do mancal de ferro fundido à carcaça de aço de baixo carbono em compressores rotativos (rolete excêntrico), utilizados em aparelhos de ar condicionado. A solda realizada de maneira falha pode permitir a perda do entreferro do motor, resultando em um ruído característico, chamado stall. Este trabalho avaliou diferentes tipos de arames, buscando garantir um processo com qualidade e baixo custo. Testes foram realizados utilizando como peças teste carcaças e mancais dos compressores. Verificou-se que o arame sólido ANSI/AWS A5.18 ER70S-6, atualmente utilizado, não é o mais indicado para a respectiva soldagem, em virtude da microestrutura e da resistência da soldagem obtida. A solução técnica apropriada é a utilização do arame ERNiFeMn-CI que elimina a fragilização das zonas parcialmente fundidas e diluídas próximos ao metal de solda, enquanto o arame metal cored E70C-6M representa um compromisso entre as propriedades da junta soldada e custo do processo. / Nowadays, with the highly selective market, with several manufacturers and suppliers of various types of products and services, quality has become a pressing need, in which a company that provides services with a low quality at serious risk of being discarded by the consumer markets. Thus, the importance of quality is that it has become a basic requirement for a company to compete and stay in the market. Companies see the Quality as a tool to reduce costs and to improve its image with the consumer market. In this context, the improvement of the image with the consumer market and costs reduction, this study was conducted in a major traditional large multinational that produces hermetic compressors to refrigeration, in order to study the welding of cast iron bearings with low carbon steel houses in rotary compressors (eccentric roller) used in air conditioners. The welding performed in a failure may allow loss of the air gap of the motor, resulting in a characteristic noise, called stall. This study evaluated different types of alloys, aiming to ensure process quality and low cost. Trials were done using low carbon steel houses and cast iron bearings of the compressors. After innumerous tests, it was found that the ANSI/AWS A5.18 ER70S-6 solid wire, currently used, is not the most suitable for their welding, in view of microstructure and resistance of the weld obtained. The appropriate technical solution is to use the wire ERNiFeMn-CI eliminating the weakening of partially melted and diluted zones near the weld metal, while metal cored wire E70C-6M represents a compromise between the properties of welded joint and the cost of the process.

Os discos de freio, durante a frenagem, são submetidos a tensões térmicas e mecânicas que podem ser relativamente altas quando muito bruscas (frações de segundo), situação em que a temperatura pode chegar a valores próximos de 600ºC. Esta variação de temperatura provoca choques térmicos que podem gerar trincas e/ou uma grande quantidade de deformação plástica no disco. A proposta deste trabalho foi a de investigar, através de experimentos, o comportamento mecânico e físico em quatro ligas de ferro fundido cinzento (A, B, C e E), utilizadas para produzir discos de freio de veículos automotivos. Para tanto, foram realizados ensaios termomecânicos de baixo ciclo em corpos de prova, entre 300ºC e 600ºC, nas condições em fase e fora de fase, adotando o critério de falha em 50% da tensão máxima (ASTM E-606) e em componentes (discos), além daqueles de difusividade térmica desde a temperatura ambiente até 600ºC. As curvas deformação em função da vida ( N) foram obtidas e analisadas segundo norma ASTM E 466/468. A análise microestrutural nos corpos de prova e peças, após os ensaios de fadiga, serviu para revelar a influência da morfologia e quantidade de grafita e da matriz sobre as propriedades mecânicas. A medição das difusividades térmicas teve como objetivo a verificação da influência do carbono equivalente e dos elementos de liga sobre esta propriedade física. Observou-se que, durante os ensaios de fadiga termomecânica em fase, em função da decomposição de parcela da cementita da perlita, houve, nos materiais, a chamada expansão grafítica, que teve influência na parte trativa do ciclo, diminuindo as tensões necessárias para se alcançar determinadas amplitudes de tensão mecânica. Pelos gráficos de amplitude de deformação mecânica em função do número de reversos para falhar, sob fadiga termomecânica em fase e fora de fase, observou-se que a melhor liga de ferro fundido cinzento foi a liga E. Esta constatação implicará em uma significativa redução dos custos de produção dos discos de freio, pois se poderá prescindir do elemento de liga Molibdênio, extremamente caro. Comparando-se os resultados de fadiga termomecânica com os de fadiga isotérmica a 25ºC, 300ºC e 600ºC, pôde-se verificar que os ensaios mais críticos foram os fora de fase, pois conduziram, comparativamente, a vidas menores. / Brake discs are submitted to thermal and mechanical stress that can be relatively high during abrupt braking action happens (fractions of seconds), causing the temperature to reach values as high as 600ºC. This temperature variation results in thermal shocks that can generate cracks and/or a large amount of plastic deformation in the disk. The main aim of this work was to investigate, through experiments, the mechanical and physical behavior of four alloys of gray cast iron (A, B, C and E), used to produce brake discs of automotives vehicles. Low cycle thermomechanical fatigue tests were carried out in components (discs) and in test specimens, between 300ºC and 600ºC, in the conditions in-phase and out-of-phase, adopting the failure criterion of 50% drop of the maximum tensile stress (ASTM E - 606). Thermal diffusivity values were measured from room temperature up to 600oC in order to analyze the effects of carbon content and alloying elements in physical properties. Curves -N were obtained and analyzed according to ASTM E 466/468 standard. Microstructural analysis was employed to reveal the influence of the matrix and morphology/amount of graphite on the mechanical properties. It was observed that, during in-phase thermomechanical fatigue tests, the volume expansion due to cementite decomposition into graphite and ferrite caused a decrease in the tensile stress necessary to achieve the mechanical strain imposed during tests. From M/2 x 2Nf graphs it was inferred that alloy E presented the best performance both in in-phase and out-of phase tests. The lack of Mo in this alloy implies in a significant reduction of cost production of the brake discs, due to the high cost of such alloying element. Out-of-phase thermomechanical fatigue tests resulted in shorter lives compared to isothermal fatigue tests carried out at 25ºC, 300ºC and 600ºC.

A aplicação do novo conceito de tratamento térmico, chamado de têmpera e partição (Q&P), desenvolvido para a obtenção de aços da terceira geração da classe AHSS (Advanced high strengh steel ou aços avançados de alta resistência), mostra-se uma alternativa para o processamento de ferros fundidos nodulares com alta resistência mecânica. No processo Q&P, o carbono presente na martensita supersaturada, formada na etapa de têmpera, é utilizado para estabilizar a austenita não transformada durante a etapa de partição, mantendo-a estável na temperatura ambiente. Essa rota de tratamento térmico consiste em realizar uma têmpera no material (após uma etapa prévia de austenitização) numa faixa de temperatura entre o Ms e Mf (temperatura de início e fim da transformação martensítica, respectivamente), seguido de um reaquecimento e manutenção a uma temperatura acima do Ms (etapa isotérmica de partição) com o objetivo de que o carbono migre da martensita supersaturada para a austenita remanescente promovendo sua estabilização. Essa partição do carbono só é possível caso a precipitação da cementita seja suprimida, e isso é conseguido com a presença de elementos de liga, como o Si e/ou Al. Neste trabalho foi feito um estudo sobre as características microestruturais e mecânicas de um ferro fundido nodular (3,47%C; 2,47%Si; 0,2%Mn) submetido ao tratamento térmico de têmpera e partição, o qual foi denominado neste trabalho como, Q&PDI (Quenched and Partitioned Ductile Iron ou Ferro Fundido Nodular Temperado e Particionado). Para isso foi realizada uma austenitização plena nas amostras, a 880°C, por duas horas, seguida de uma têmpera em óleo pré-aquecido nas temperaturas de 140 e 170°C. A etapa de partição foi feita nas temperaturas de 300, 375 e 450°C, com intervalos de tempo variando de 5 a 120 minutos. A caracterização microestrutural foi realizada através de microscopia ótica, microscopia eletrônica de varredura e EBSD. A técnica de difração de raios-X foi empregada para quantificar a fração volumétrica e o teor de carbono na austenita retida. Ensaios de dilatometria, difração de raios-X \"in situ\" e nanoindentação foram empregados para auxiliar na análise das transformações de fases que ocorreram na etapa de partição, como a transformação bainítica e a precipitação de carbonetos de transição nas placas de martensita. A caracterização mecânica foi feita através de ensaios de tração, impacto, dureza, nanoindentação, tenacidade à fratura e resistência à fadiga. Ensaios de compressão auxiliaram na análise da transformação martensítica induzida por deformação. Os resultados obtidos mostraram que é possível obter ferros fundidos nodulares com alta resistência mecânica (limite de resistência >1450 MPa), com consideráveis ductilidade (de até 9%) e energia absorvida sob impacto (de até 81 J), bem como tenacidades à fratura de 55 MPa.m1/2 e limites de fadiga de 550 MPa. Este comportamento é proporcionado por uma microestrutura singular, constituída por uma dispersão homogênea de placas de martensita numa matriz de ausferrita bastante refinada, com consideráveis frações volumétricas de austenita retida (max. 23%). / Quenching and partitioning (Q & P), a new heat treatment concept developed to obtain third generation AHSS (Advanced High Strength Steel), is an alternative for processing of nodular cast irons in order to obtain high mechanical strength. In the Q & P process, the carbon present in the supersaturated martensite formed in the quenching step diffuses towards the untransformed austenite during the partition step, keeping it stable at room temperature. This heat treatment route consists of quenching the material (after a previous step of austenitization) in a temperature range between Ms and Mf (beginning and end temperature of the martensitic transformation, respectively), followed by reheating and maintenance at a temperature above the Ms (isothermal stage of partition) allowing the carbon to migrate from the supersaturated martensite to the remaining austenite, promoting its stabilization. This partition of carbon is only possible if precipitation of cementite is suppressed; this is achieved adding alloying elements such as Si and/or Al. In this work a study was made on the microstructural and mechanical characteristics of a ductile iron (3.47%C; 2.47%Si; 0.2%Mn), submitted to a Q&P heat treatment, in this work named Q & PDI (Quenched and Partitioned Ductile Iron). A full sample austenitization was carried out at 880 ° C for two hours, followed by a pre-heated oil quanching at temperatures of 140 and 170 ° C. The partitioning step was at temperatures of 300, 375 and 450Â ° C, with time intervals ranging from 5 to 120 minutes. Microstructural characterization was performed through optical microscopy, scanning electron microscopy and EBSD. The X-ray diffraction technique was used to quantify the volumetric fraction and the carbon content in the retained austenite. Dilatometry, X-ray diffraction \"in situ\" and nanoindentation were also used to aid in the analysis of the phase transformations that occurred in the partitioning stage, such as the bainitic transformation and the precipitation of transition carbides in the martensite plates. Mechanical characterization was performed through tensile, impact, hardness, nanoindentation, fracture toughness and fatigue strength tests. Compression tests aided in the analysis of the deformation induced martensitic transformation. The results showed that it is possible to obtain nodular cast irons with high mechanical strength (resistance limit> 1450 MPa), with considerable ductility (up to 9%) and energy absorbed under impact (up to 81 J), as well as fracture toughness of 55 MPa.m -1 / 2 and fatigue limits of 550 Mpa. This behavior is provided by a unique microstructure, consisting of a homogeneous dispersion of martensite plates in a very refined ausferrite matrix, with considerable volumetric fractions of retained austenite (max. 23%).

As ligas de ferro fundido branco multicomponente são aços rápidos resistentes ao desgaste em temperaturas elevadas. Estes aços apresentam carbonetos eutéticos do tipo MC e M2C quando no estado bruto de fundição. Neste trabalho foi caracterizada a microestrutura dos produtos de decomposição após tratamentos térmicos do carboneto eutético metaestável M2C de uma liga de ferro fundido multicomponente com composição (em % peso): 2 wt% de C e 5 wt% de cada um dos elementos V, Cr, Mo e W, o restante é Fe. A liga de ferro fundido multicomponente foi tratada isotermicamente a 950°C e a 1.050°C por tempos crescentes em forno poço com sal fundido e em forno mufla inseridas em ampolas de sílica sob vácuo. Os tempos de tratamento foram: 10s, 100s, 600s, 1.800s, 1 hora, 2 horas e 15 horas. As técnicas de caracterização envolvidas foram: difração de raios X de carbonetos extraídos, metalografia através de ataques seletivos, microscopia eletrônicas de varredura (SEM), microscopia eletrônica de transmissão e varredura (STEM), espectrometria por energia dispersiva de raios X (EDS) e difração de elétrons por área selecionada (SAED). Os resultados sugerem que além dos carbonetos MC, M2C irregular e regularcomplexo e M7C3 descritos na literatura, observa-se a presença de um novo tipo de carboneto M2C metaestável rico em cromo na liga no estado bruto de fundição. Os carbonetos metaestáveis M2C se decompõem em carbonetos M6C, em carbonetos M7C3 e finalmente MC globular com o aumento da temperatura e/ou com tempos crescentes de tratamento térmico. O carboneto M7C3 após tratamento térmico de longa duração passa por um processo de esferoidização e depois engrossamento. / Multicomponent White Cast Iron are high temperature wear resistant ferrous alloys, presenting eutectic MC and M2C carbides in their as cast structure. In the present work the decomposition microstructures of the metastable M2C carbide after heat treatments was characterized in a model multicomponent white cast iron with composition (in weight): 2 wt% C and 5 wt% of each of the carbide forming alloying elements V, Cr, Mo and W, and with the balance Fe. The model multicomponent alloy was isothermally treated at 950°C and 1.050°C for increasing time periods using a salt bath pit furnace and a muffle furnace using samples encapsulated in silica glass ampoules under vacuum. Treatment times were: 10s, 100s, 600s, 1.800s, 1 hour, 2 hours and 15 hours. Characterization techniques used were: X Ray diffraction of extracted carbides, optical microscopy metallography with selective etching techniques, scanning electron microscopy (SEM), X ray energy dispersive spectroscopy (EDS), transmission and scanning electron microscopy (STEM) and selected area electrons diffraction (SAED). Besides the MC, irregular and regular-complex M2C and M7C3 described in the literature, it was found in the as cast alloy also a hitherto unknown chromium rich M2C carbide. The metastable M2C carbides decompose into M6C carbides, then M7C3 and finally globular MC with increasing temperatures and/or increasing times at heat treatment temperatures. After long times heat treatments the M7C3 carbides, spheroidize and coarsen.