The mechanism of tensile yield in an age-hardened steel containing γ′ (ordered Ni3Ti) precipitates

Singhal, L. K.; Martin, J. W.

doi:10.1016/0001-6160(68)90061-8

Cited by 57 publications

(16 citation statements)

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“…This type of steel is frequently used [14,15] in the temperature range between 773 and 873 K and this is exactly the range of highest susceptibility to M 23 C 6 precipitation [5,6]. The results presented here clearly showed that the chromium carbide precipitates are the cause of susceptibility to intergranular corrosion and led to the conclusion that the addition of stabilizing elements does not suppress precipitation of M 23 C 6 , even when the stabilizers are present in large amounts [16]. In order to avoid sensitization, it is necessary to submit the steel, previous to its use, to a stabilizing heat treatment known as stabilizing anneal [18].…”

Section: Resultsmentioning

confidence: 60%

“…Furthermore, for stabilized austenitic stainless steels the critical temperature range is between 753 and 873 K due to the favored chromium carbide precipitation (M 23 C 6 ) in this temperature range [14,15]. M 23 C 6 carbides have been found [16] in stabilized austenitic stainless steels in which the Ti/C mass ratio was as high as 34 when the stoichiometric ratio is only about 4. So, it is worthy of note that the addition of stabilizing elements does not entirely suppress precipitation of M 23 C 6 , even for large amounts of stabilizing elements [17].…”

Section: Introductionmentioning

confidence: 99%

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Microstructure and intergranular corrosion of the austenitic stainless steel 1.4970

Terada

Saiki

Costa

et al. 2006

Journal of Nuclear Materials

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Section: Resultsmentioning

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Microstructure and intergranular corrosion of the austenitic stainless steel 1.4970

Terada

Saiki

Costa

et al. 2006

Journal of Nuclear Materials

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“…M 23 C 6 carbides have been found 43) in stabilized steels in which the Ti/C ratio was as high as 34 when the stoichiometric ratio is only 5. The precipitation of M 23 C 6 becomes comparatively easier in relation to that of MC carbides as the temperature is decreased.…”

Section: MCmentioning

confidence: 99%

Decomposition of Austenite in Austenitic Stainless Steels

2002

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Austenitic stainless steels are probably the most important class of corrosion resistant metallic materials. In order to attain their good corrosion properties they rely essentially on two factors: a high chromium content that is responsible for the protective oxide film layer and a high nickel content that is responsible for the steel to remain austenitic. Thus the base composition is normally a Fe-Cr-Ni alloy. In practice the situation is much more complex with several other elements being present, such as, Mo, Mn, C, N among others. In such a complex situation one almost never has a single austenite phase but other phases invariably form. Those phases are, with few exceptions, undesirable and they can be detrimental to the corrosion and mechanical properties. It is therefore of considerable importance to study the formation of such phases. In this work the decomposition of austenite in austenitic stainless steels is reviewed in detail. First the binary equilibrium diagrams relevant to the system Fe-Cr-Ni are briefly presented as well as other diagrams, such as the Schaeffler diagram, that traditionally have been used to predict the phases present in these steels as a function of composition. Secondly the precipitation of carbides and intermetallic phases is presented in detail including nucleation sites and orientation relationships and the influence of several factors such as composition, previous deformation and solution annealing temperature. Next, the occurrence of other constituents such as nitrides, sulfides and borides is discussed. TTT diagrams are also briefly presented. Finally the formation of martensite in these steels is discussed.KEY WORDS: austenitic stainless steel; precipitation behaviour; carbides; intermetallic compounds; TTT diagram; strain induced martensite. Phase DiagramsPhase diagrams are important to predict the phases present in the austenitic stainless steels. Nevertheless they have limitations due to the complexity of multicomponent thermodynamic calculations and also due to the transformation kinetics that may prevent the attainment of the equilibrium phases. Regarding the first limitation, the number of relevant components is often more than five and published diagrams are rarely found to contain more than four components. As to the second limitation, the diffusion of alloying elements in austenite can be very slow and the precipitation of certain intermetallic compounds can take thousands of hours. Equilibrium DiagramsIn this section the most relevant features of the binary diagrams 3,4) Fe-Cr, Fe-Ni, Cr-Ni, Fe-Mo, Fe-Ti, Ni-Ti, FeNb, Fe-Mn and Fe-Si are considered. Next the Fe-Cr-Ni and Fe-Cr-Mo ternary diagrams and the quaternary FeCr-Ni-Mo diagram are discussed. The individual characteristics of each phase will be presented later in this review.The two main features of the Fe-Cr diagram, shown in Fig. 1, which are relevant to austenitic stainless steels, are the ferrite stabilizing character of Cr and the presence of sigma (s) phase.The Fe-Ni diagram clearly shows the strong ...

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“…A286 superalloy is strengthened by the precipitation of the ordered fcc gamma prime (γ′) Ni 3 (Al,Ti) phase [3,4], which is coherent with the matrix [5,6]. Since, according to Seifollahi et al [7], the γ′ phase is unstable, after a sufficiently long aging treatment at sufficiently high temperature and dissolves to form the hcp eta (η) Ni 3 Ti phase.…”

Section: Introductionmentioning

confidence: 99%

Study of influence of gamma prime and eta phases on corrosion behaviour of A286 superalloy by using electrochemical potentiokinetic techniques

2015

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The mechanism of tensile yield in an age-hardened steel containing γ′ (ordered Ni3Ti) precipitates

Cited by 57 publications

References 9 publications

Microstructure and intergranular corrosion of the austenitic stainless steel 1.4970

Microstructure and intergranular corrosion of the austenitic stainless steel 1.4970

Decomposition of Austenite in Austenitic Stainless Steels

Study of influence of gamma prime and eta phases on corrosion behaviour of A286 superalloy by using electrochemical potentiokinetic techniques

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