The thermodynamics of interactive co-segregation of phosphorus and alloying elements in iron and temper-brittle steels

Guttmann, M.; Dumoulin, Ph.; Wayman, Michael L.

doi:10.1007/bf02647825

Cited by 170 publications

(42 citation statements)

References 30 publications

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“…A literatura é vasta sobre o assunto de fragilidade de revenido, (21)(22)(23)(24)(25)(26)(27)(28)(29) dividida em dois fenômenos nos aços baixa liga. (21)(22)(23) O primeiro, da fragilidade de revenido clássica, presente após revenido em alta temperatura, (21)(22)(23) entre 500°C e 600°C.…”

Section: Resultados Do Presente Trabalho E Correlação Com a Fragilidaunclassified

Aços Ferramenta Para Trabalho a Quente Com Baixo Teor De Silício: Caracterização E Aplicações

Mesquita¹,

Barbosa²,

Gonçalves³

et al. 2008

TMM

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ResumoOs aços ferramenta para trabalho a quente são empregados como matrizes para conformação de metais em alta temperatura. Recentemente, novos aços ferramenta, com menor teor de silício, têm sido utilizados, gerando substancial melhoria de desempenho das matrizes. O presente trabalho discute resultados da caracterização mecânica e microestrutural de tais aços, também apresentando algumas análises de casos. As propriedades mecânicas foram avaliadas quanto à dureza e tenacidade em impacto, em função da temperatura de revenimento. Para caracterização microestrutural, foi utilizada a técnica de microscopia eletrônica de transmissão, com o objetivo de caracterizar os carbonetos secundários, os principais responsáveis pelo endurecimento dos materiais. São observadas diferenças significativas dos carbonetos secundários em função do teor de silício, estando relacionadas, diretamente, às propriedades mecânicas avaliadas. A redução do teor de silício diminui a presença de carbonetos finos e agulhados; isto pode explicar a menor tenacidade dos aços ferramenta de alto teor de silício, sendo proposto um possível mecanismo. Desta forma, os resultados mecânicos e microestruturais justificam o aumento de desempenho desta nova classe de aços ferramenta para trabalho a quente, com menor teor de silício. Palavras-chave: Aço-ferramenta; Silício; Tenacidade; Desempenho. LOW SILICON HOT WORK TOOL STEELS: CHARACTERIZATION AND APPLICATIONS AbstractHot work tool steels are mainly used as dies for hot forming processes. New grades have been recently developed, with lower silicon content, leading to a substantial performance increase. The present paper describes the mechanical properties and microstructural characterization of such hot work steels, as well as case studies. Hardness and toughness were determined for a wide range of tempering temperatures; concerning microstructural characterization, transmission electron microcopy was used for observing secondary carbides -the main responsible for the hot strength of these steels. Important differences were observed on the secondary carbides, which are considered responsible for the differences on the mechanical properties. The reduction in silicon content reduces the amount of fine needle shaped carbides; this can explain the lower toughness of high silicon content grades and a possible mechanism is proposed. Therefore, the microstructural and mechanical results enable the understanding of the higher performance of this new class of hot work tool steels, with lower silicon content.

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Section: Resultados Do Presente Trabalho E Correlação Com a Fragilidaunclassified

Aços Ferramenta Para Trabalho a Quente Com Baixo Teor De Silício: Caracterização E Aplicações

Mesquita¹,

Barbosa²,

Gonçalves³

et al. 2008

TMM

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“…[18][19][20] Pre-exponential factors and activation energies of P diffusion in paramagnetic and ferromagnetic regions of Fe are 2.87ϫ10 Ϫ2 m 2 /s, 271 kJ/mol, and 1.38ϫ10 m 2 /s, 332 kJ/mol, respectively. 21) According to these expressions, the change in grain boundary concentration during the each heat treatment is estimated.…”

Section: )mentioning

confidence: 98%

Magnetic Properties and Recrystallization Texture Evolutions of Phosphorus-bearing Non-oriented Electrical Steel Sheets

Tanaka¹,

Yashiki²

2007

ISIJ Int.

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The effect of phosphorus (P) on magnetic properties and also on recrystallization texture of non-oriented electrical steel sheets has been investigated to develop core materials with low core loss and high permeability. Specimens containing different amounts of P were cold-rolled to various thicknesses, i.e. with various cold-rolling reductions, and annealed for recrystallization and grain growth. Magnetic induction of the steel with a large amount of P was higher than that of the steel with a small amount of P. Moreover, magnetic induction of the steel with a large amount of P slightly decreased with reduction of sheet thickness, i.e. with an increase in cold-rolling reduction, whereas magnetic induction of the steel with a small amount of P dramatically decreased. The most effective way to reduce core loss was to reduce thickness of electrical steel sheets. Therefore, P-bearing thin gauge non-oriented electrical steel sheets achieved low core loss and high permeability. The typical magnetic properties of P-bearing non-oriented electrical steel sheets with a thickness of 0.27 mm were 16.6 W/kg in W10/400 and 1.73 T in B50. These excellent magnetic properties were provided by the recrystallization texture control by P. {111}͗112͘ component in recrystallization texture, which deteriorates magnetic properties of electrical steel sheets, was suppressed during recrystallization. Furthermore, {j 1 , F, j 2 }ϭ{25°, 10-15°, 45°} component significantly developed at the expense of {111}͗112͘ component during grain growth. P segregation at initial grain boundaries would be responsible for this texture evolution. Accordingly, P would greatly contribute to the improvement of magnetic properties of nonoriented electrical steel sheets through the recrystallization texture control.

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“…Segregation formulation was developed by Guttmann and Mclean in a ternary system (Fe, M, I) [4] based on the sublattice model in melt salts and stoichiometric phases contributed by Hillert et al [5] . Li et al extended the segregation equation into a five-element system [6] , and generalized it into a multicomponent system as [7] : [7,8], assuming that interaction energy keeps the same on grain boundaries and in matrix and omitting the interaction between impurities and vacancy and between metal element and iron, a series of parameters [7,8] can be listed as follows:…”

Section: Trip Steel Containing Pmentioning

confidence: 99%

Application of Thermodynamics and Kinetics in Materials Engineering

Li¹

2012

Thermodynamics - Fundamentals and Its Application in Science

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The thermodynamics of interactive co-segregation of phosphorus and alloying elements in iron and temper-brittle steels

Cited by 170 publications

References 30 publications

Aços Ferramenta Para Trabalho a Quente Com Baixo Teor De Silício: Caracterização E Aplicações

Aços Ferramenta Para Trabalho a Quente Com Baixo Teor De Silício: Caracterização E Aplicações

Magnetic Properties and Recrystallization Texture Evolutions of Phosphorus-bearing Non-oriented Electrical Steel Sheets

Application of Thermodynamics and Kinetics in Materials Engineering

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