The formation of ferrite and sigma-phase in some austenitic stainless steels

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

doi:10.1016/0001-6160(68)90039-4

Cited by 69 publications

(25 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…25) In this case the sigma phase precipitation is accelerated in a subsequent aging treatment. 67,68) The rate of s-phase precipitation from ferrite is about 100 times more rapid than the rate of s-phase precipitation directly from austenite. 69) 4.1.2.…”

Section: Topologically Close Packed Phases (Tcp Phasesmentioning

confidence: 99%

Decomposition of Austenite in Austenitic Stainless Steels

2002

View full text Add to dashboard Cite

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 ...

show abstract

Section: Topologically Close Packed Phases (Tcp Phasesmentioning

confidence: 99%

Decomposition of Austenite in Austenitic Stainless Steels

2002

View full text Add to dashboard Cite

show abstract

“…Singhal and Martin (19) have shown that sigma phase tends to nucleate on ferrite-austenite boundaries. Ferrite is then preferentially consumed d u r i n g t h e growth of sigma.…”

Section: It Has Beenmentioning

confidence: 99%

Effects of welding on weldment mechanical performance in two austenitic steels

Strum¹

1982

View full text Add to dashboard Cite

“…More precisely, precipitation of r phase has been reported after aging in the temperature range from 773 K to 1173 K (500°C to 900°C). [1][2][3][4] 1138 K (865°C) has been identified as the most critical temperature for r phase formation [5] and certainly corresponds to the nose of the Time-Temperature-Transformation curve. Secondary M 23 C 6 carbides start precipitating below 1323 K (1050°C).…”

Section: Introductionmentioning

confidence: 99%

Isothermal and Cyclic Aging of 310S Austenitic Stainless Steel

Parrens

Lacaze

Malard

et al. 2017

Metall Mater Trans A

View full text Add to dashboard Cite

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. Unusual damage and high creep strain rates have been observed on components made of 310S stainless steel subjected to thermal cycles between room temperature and 1143 K (870°C). Microstructural characterization of such components after service evidenced high contents in sigma phase which formed first from d-ferrite and then from c-austenite. To get some insight into this microstructural evolution, isothermal and cyclic aging of 310S stainless steel has been studied experimentally and discussed on the basis of numerical simulations. The higher contents of sigma phase observed after cyclic agings than after isothermal treatments are clearly associated with nucleation triggered by thermal cycling.

show abstract

The formation of ferrite and sigma-phase in some austenitic stainless steels

Cited by 69 publications

References 2 publications

Decomposition of Austenite in Austenitic Stainless Steels

Decomposition of Austenite in Austenitic Stainless Steels

Effects of welding on weldment mechanical performance in two austenitic steels

Isothermal and Cyclic Aging of 310S Austenitic Stainless Steel

Contact Info

Product

Resources

About