A critical review of precipitation behaviour in 1CrMoV rotor steels

Senior, B.A.

doi:10.1016/0025-5416(88)90516-2

Cited by 80 publications

(28 citation statements)

References 19 publications

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“…The MX (MC) precipitates rich in vanadium are precipitated during tempering in a fine-dispersive form and are responsible for an increase in hardness and creep strength. A similar effect of the secondary hardness was observed in a traditional low-alloyed Cr-Mo-V steels [20]. Temperature of treatment higher than 650…”

Section: Weldability Of T24 Steelsupporting

confidence: 62%

“…Molybdenum enrichment of MC precipitations which are vanadium-rich can lead to the formation of complexes called "H-carbide" [20]. The "H-carbide" complexes consist of a horizontal precipitation of VC and vertical precipitations of M 2 C carbides (Mo-rich carbides) nucleating in parallel at counter-sides of VC precipitates (Fig.…”

Section: Description Of T24 Steelmentioning

confidence: 99%

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Microstructure, properties and welding of T24 steel – critical review

Golański¹,

JASAK²,

Słania³

2021

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In this paper a new bainitic 7CrMoVTiB10-10 (T24) steel has been described on the basis of our own research results and a review of relevant literature. The T24 creep-resistant steel is known to be intended for membrane walls in power-generation units operating at supercritical steam parameters. Chemical composition, thermal treatment, microstructure and mechanical properties of T24 steel were characterized. Moreover, the processes of microstructure degradation during ageing/creeping and their effects on mechanical properties have been shown. Weldability of T24 steel and the problems connected with cracking of its homogeneous joints, as well as the methods of preventing them, are given in the paper. K e y w o r d s : bainitic steels, microstructure, welding, cracking

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Section: Weldability Of T24 Steelsupporting

confidence: 62%

Section: Description Of T24 Steelmentioning

confidence: 99%

Microstructure, properties and welding of T24 steel – critical review

Golański¹,

JASAK²,

Słania³

2021

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“…The precipitation and growth of the carbides M 6 C leads to the reduction of chromium in the matrix what results in reduction of solid solution strengthening and consequently in the recovery and recrystallisation of the matrix. The enrichment of MC carbides with molybdenum makes possible the nucleation on the interface boundary of MC carbide/acicular ferrite of M 2 C type precipitations [14]. Above mentioned complexes created at the expense of MC carbides are referred to as "H -carbides" and may lead to the decrease in creep resistance of materials.…”

Section: Macroscopic and Microscopic Examinationmentioning

confidence: 99%

Examination of Coil Pipe Butt Joint Made of 7CrMoVTiB10-10(T24) Steel After Service

Golański¹,

Gawień²,

Słania³

2012

Archives of Metallurgy and Materials

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BADANIE PODCZAS REMONTU ZŁĄCZY DOCZOŁOWYCH RUR WYKONANYCH ZE STALI 7CrMoVTiB10 -10(T24)The paper presents the results of examination of coil pipe butt joint made of 7CrMoVTiB10-10 steel (T24). Tested joint was in service for approximately 12 000 hours at the temperature of 540• C and pressure of 5.48MPa. Tests have revealed that the structure of all regions of the homogenous welded joint are correct and without any welding imperfections. Operation of the weld contributed mainly to advantaged precipitation of carbides especially on grain boundaries -frequently in the contact area of three grains' boundaries as well as in the form of continuous network of precipitates. The measurement showed high hardness of the weld, what indicates high stability of the microstructure. It makes possible to find that post-weld heat treatment is indispensable.Keywords: T24 steel, welded joint, microstructure W pracy przedstawiono wyniki badań doczołowego złącza spawanego rury wężownicy ze stali 7CrMoVTiB10-10 (T24). Badane złącze eksploatowane było przez około 12 000 godzin w temperaturze 540• C przy ciśnieniu 5.48 MPa. Przeprowadzone badania wykazały prawidłową budowę we wszystkich strefach jednorodnego złącza spawanego bez niezgodności spawalniczych. Eksploatacja badanego złącza przyczyniła się przede wszystkim do uprzywilejowanego wydzielania węglików po granicach ziaren, często na styku trzech granic ziaren oraz w postaci tzw. ciągłej siatki wydzieleń. pomiar twardości wykazał wysoką twardość złącza, co wskazuje na dużą stabilność mikrostruktury. Pozwala to na stwierdzenie o konieczności stosowania zabiegów obróbki cieplnej po spawaniu.

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“…O desenvolvimento de fornos a vácuo tornou possível a produção de aços de alta pureza, e a implantação do método de fusão secundária garantiu melhor qualidade dos aços para rotor forjado com uma maior homogeneidade de composição e estrutura de solidificação uniforme. Dentre esses métodos está a refusão por arco elétrico em vácuo (VAR), que possibilita produzir ligas compostas por elementos reativos e reduzir elementos deletérios às propriedades [1,2]. O objetivo deste trabalho foi avaliar as diferenças na microestrutura e nas propriedades mecânicas a temperatura ambiente entre amostras de aço 1Cr-Mo-V que foram fundidas apenas em forno elétrico aberto e amostras que, posteriormente, foram refundidas no forno a arco elétrico a vácuo da COPPE/UFRJ.…”

Section: Introductionunclassified

AVALIAÇÃO DA REFUSÃO DE AÇOS 1Cr-Mo-V FORJADOS PARA ROTORES DE TURBINAS A VAPOR

Roza¹,

Almeida²,

Cardoso³

et al. 2018

ABM Proceedings

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ResumoOs aços 1Cr-Mo-V forjados são largamente utilizados em rotores de turbinas a vapor, e o seu desempenho em condições de fluência vem sendo melhorado por tecnologias de fabricação. Sendo assim, os fatores metalúrgicos que afetam o comportamento em fluência dessa classe de material vem sendo estudados. O objetivo deste trabalho foi a avaliar as diferenças na microestrutura e nas propriedades mecânicas, a temperatura ambiente, entre amostras de aço 1Cr-Mo-V fundidas em forno elétrico aberto e amostras que posteriormente refundidas no forno a arco elétrico a vácuo (VAR). As amostras foram forjadas a quente e tratadas termicamente em mesmas condições. Para a avaliação das diferenças, foram comparadas as microestruturas nas duas condições e feitas análises de inclusões através de microscopia ótica e microscopia eletrônica de varredura. Foram realizados ensaios de dureza e de tração a temperatura ambiente. Os resultados mostraram que a refusão foi eficiente na redução do teor de alguns elementos deletérios e na redução do tamanho e do número de inclusões, sulfetos de manganês e silicatos de manganês, além de contribuir para uma distribuição mais homogênea tanto das inclusões como da microestrutura bainítica apresentada. As medidas de propriedades mecânicas a temperatura ambiente não mostraram alterações significativas na resistência. Porém, houve aumento na ductilidade, manifestado por uma maior redução de área. Palavras-chave: Aço 1Cr-Mo-V forjado; Refusão à arco em vácuo (VAR); Análise microestrutural; Turbinas a vapor. EVALUATION OF REMELTING IN 1Cr-Mo-V STEEL FORGINGS FOR STEAM TURBINE ROTORS AbstractThe 1Cr-Mo-V forging steels are widely used in the manufacture of steam turbine rotors, and its performance under creep conditions has been improved by the development of manufacturing technologies. Thus, metallurgical factors affecting the creep behavior of this class of materials have been widely studied. The objective of this work was to evaluate the differences in the microstructure and mechanical properties, at room temperature, between 1Cr-Mo-V steel samples that were melted in open electric furnace and samples that were subsequently remelted in vacuum arc furnace (VAR). The two samples were hot forged and heat treated under the same conditions. For the evaluation, the microstructures were compared between both conditions. The analysis of inclusions was made by optical and scanning electron microscopy. Additionally, hardness and tensile tests were conducted at room temperature. The results showed that the remelting was effective in reducing the content of some deleterious elements and the size and number of inclusions, characterized as manganese sulphides and manganese silicates; and contributed to a more homogeneous distribution of both inclusions and the bainitic microstructure presented. The strength in ambient temperature presented no significant alterations between the samples. However, it was observed an increase in the ductility, manifested in a higher reduction of area.

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A critical review of precipitation behaviour in 1CrMoV rotor steels

Cited by 80 publications

References 19 publications

Microstructure, properties and welding of T24 steel – critical review

Microstructure, properties and welding of T24 steel – critical review

Examination of Coil Pipe Butt Joint Made of 7CrMoVTiB10-10(T24) Steel After Service

AVALIAÇÃO DA REFUSÃO DE AÇOS 1Cr-Mo-V FORJADOS PARA ROTORES DE TURBINAS A VAPOR

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