Nichtrostende Stähle

Heimann, Winfried; Oppenheim, Rudolf; Wessling, W.

doi:10.1007/978-3-642-82208-7_13

Cited by 1 publication

(2 citation statements)

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“…2.1c the austenitic phase field in Stainless steels are alloyed with copper to reduce general corrosion e.g. in nonoxidising acid solution [4]. In contrast to molybdenum, copper stabilises austenite and raises the activity of interstitials.…”

Section: Molybdenum and Coppermentioning

confidence: 99%

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Constitution

Berns¹,

Gavriljuk²,

Riedner³

2012

High Interstitial Stainless Austenitic Steels

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The constitution of high interstitial steels describes the state of atomic order in thermodynamic equilibrium. It depends on the three variables of state: concentration of alloying elements in iron, temperature and pressure. A region that is in the same state of order is known as a phase. Nitrogen is a volatile element and therefore the gas phase and especially the partial pressure of N 2 has to be taken into account. The liquid phase appears during melting, solidification and welding. Of the solid state phases austenite, d-ferrite, carbides, nitrides and sigma phase are to be expected. To cope with such a complex alloy system the commercial software program THERMO-CALC TM , version R with TCFE4 database [1] was used to calculate the constitution of multi-component HIS.It depends on experimental data and theoretical models covering a wide range of steel compositions by minimizing the Gibb's free energy [2]. The program provides phase diagrams as isothermal or isoplethal sections through a system. Also the mole, mass or volume fraction of phases in a given steel may be plotted over the temperature. In addition the chemical composition of each phase is available. In the high temperature range from solidification to solution annealing, which are of practical importance, less deviation from the calculated equilibrium is to be expected than at lower temperatures. However during quenching the kinetics of precipitation are of interest only. It is shown in the next chapter that the atoms in homogeneous austenite are not necessarily distributed evenly, but that microsegregation (mm range) or short range atomic decomposition (clustering, nm range) may cause a chemical inhomogeneity which is not covered by the calculations. Tramp elements are not considered to reduce the computing time except for manufactured grades.Limited experimental verification was in good agreement with the simulation. Therefore the calculated phase diagrams are taken as a reasonable guideline to reveal tendencies.

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Section: Molybdenum and Coppermentioning

confidence: 99%

“…Alloying stainless steels with molybdenum is a common measure to impede pitting corrosion [4]. As this element is a carbide former and a ferrite stabilizer, the question is what content is permitted in austenitic CrMnCN steels.…”

Section: Molybdenum and Coppermentioning

confidence: 99%