Weldability Approach to Duplex Stainless Steels Using Multicomponent Phase Diagrams

2005 ◽  
Vol 475-479 ◽  
pp. 2765-2768 ◽  
Author(s):  
Antonio J. Ramirez ◽  
Sérgio Duarte Brandi
Keyword(s):  
Phase Diagram ◽  
Phase Transformations ◽  
Phase Diagrams ◽  
Stainless Steels ◽  
Equilibrium Phase ◽  
Duplex Stainless Steels ◽  
Pseudobinary Phase Diagram ◽  
Equilibrium Process ◽  
Diagram Approach ◽  
Joint Microstructures

Welding is a non-equilibrium process. However, some weldability issues, as the extension of the heat-affected zone (HAZ) can be addressed using equilibrium phase diagrams. The 70 wt% Fe-Cr-Ni pseudo-binary phase diagram is commonly used to establish the phase transformations during welding of duplex stainless steels. The predicted results are assumed to be reasonably good for most of the duplex stainless steels. Thermodynamic calculations were used to determine multicomponent phase diagrams and volumetric fraction of phases present as a function of temperature several commercial duplex stainless steels. Results showed that simplified pseudobinary phase diagram approach is valid to estimate welded joint microstructures only for the low alloy duplex stainless steels as UNS S32304, but phase transformations and mainly solidification paths of high alloy duplex stainless steels should predicted only using a multi-component phase diagram.

scholarly journals Thermodynamic reassessment of the Mn-Ni-Si system

2015 ◽  
Vol 51 (2) ◽  
pp. 125-132 ◽  
Author(s):  
B. Hu ◽  
Y. Du ◽  
J.J. Yuan ◽  
Z.F. Liu ◽  
Q.P. Wang
Keyword(s):  
Experimental Data ◽  
Phase Diagram ◽  
Phase Diagrams ◽  
Thermodynamic Parameters ◽  
Ternary Phase ◽  
Sublattice Model ◽  
Diagram Approach ◽  
Measured Phase

Iased on the new experimental data available in the literature, the Mn-Ni-Si system has been reassessed using the CALPHAD (CALculation of PHAse Diagram) approach. Compared with the previous modeling, the ?8 and ?12 ternary phases were treated as the same phase according to the new experimental data. The Mn3Si phase was described with two sublattice model (Mn, Ni)3(Si)1. The reported new ternary phase ? was not considered in the present work. Comprehensive comparisons between the calculated and measured phase diagrams showed that a set of thermodynamic parameters of the Mn-Ni-Si system obtained in this work was more accurate than the previous one.

Slag Investigations from Bronze Age Copper Smelting Sites

2017 ◽  
Vol 891 ◽  
pp. 608-612 ◽  
Author(s):  
Roland Haubner ◽  
Susanne Strobl
Keyword(s):  
Phase Diagram ◽  
Chemical Composition ◽  
Phase Diagrams ◽  
Bronze Age ◽  
Equilibrium Phase ◽  
Eastern Alps ◽  
Copper Production ◽  
Copper Smelting ◽  
Smelting Process ◽  
Melting Properties

During the Bronze Age intensive mining and smelting activities for copper production took place in the Eastern Alps. To get information about the copper smelting process, the elemental compositions of slags are marked in equilibrium phase diagrams (e.g. FeO-CaO-SiO2) and so the melting properties can be estimated. Doing so you have to keep in mind that slags have complex compositions and phase diagrams are available for three compounds only. For the analytical measurements it has to be ensured that only molten parts of the slag are measured and not contamination of other ambient material. Spot and area measurements by SEM-EDX are useful to get realistic data. In this case a complete correlation between the image of the analyzed area, the microstructure and the chemical composition of the sample is necessary. For marking spots in the phase diagram the calculation method has to be described exactly. For our results we calculated the ratio FeO-SiO2-CaO(+MgO+Al2O3). From the morphology of the observed phases, their chemical composition and the data from the phase diagram a solidification sequence can be suggested. We recommend this method because measurements by e.g. XRF provide rather general composition values. If the slag samples are inhomogeneous, unrealistic melting points are read from the phase diagram. Inhomogeneities can be caused by soil contaminations, which are not part of the molten slag, or by corrosion, when some phases were attacked and changed during storage in soil.

Duplex Stainless Steels: A Dozen of Significant Phase Transformations

2012 ◽  
Vol 322 ◽  
pp. 163-174 ◽  
Author(s):  
Angelo Fernando Padilha ◽  
D.J.M. Aguiar ◽  
R.L. Plaut
Keyword(s):  
Phase Transformations ◽  
Stainless Steels ◽  
Duplex Stainless Steels ◽  
Chromium Nitride ◽  
Solution Annealing ◽  
Phase Precipitation ◽  
Significant Phase ◽  
Strain Induced Martensite ◽  
Austenite Recrystallization ◽  
Decomposition Phase

During processing or use, duplex stainless steels are subject to a great number of significant phase transformations, such as solidification, partial ferrite transformation to austenite, ferrite eutectoid decomposition to sigma phase plus austenite, chi phase precipitation, chromium carbide precipitation, chromium nitride precipitation, ferrite spinodal decomposition, phase dissolution during solution annealing, forming of two types (epsilon and alpha prime) of strain induced martensite, martensite reversion to austenite, ferrite and austenite recrystallization. This paper summarizes the phase transformations that occur (individually or combined) in duplex stainless steels and presents some new results.

scholarly journals Thermodynamic model for lattice point defect-mediated semi-coherent precipitation in alloys

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Maylise Nastar ◽  
Lisa T. Belkacemi ◽  
Estelle Meslin ◽  
Marie Loyer-Prost
Keyword(s):  
Phase Diagram ◽  
Phase Transformations ◽  
Point Defect ◽  
Point Defects ◽  
Lattice Point ◽  
Parent Phase ◽  
Equilibrium Phase ◽  
Precipitation Kinetic ◽  
Coherent Phase

AbstractThe formation of precipitates with an atomic volume different from their parent phase eventually leads to a loss of the lattice continuity at the matrix–precipitate interface. Here, we show the creation or removal of lattice sites mediated by lattice point defects is an accommodation mechanism of the coherency loss and even a precipitation driving force. We introduce a thermodynamic approach that rationalizes the selection of phases resulting from chemical and crystallographic constraints in relation to point defect properties. The resulting semi-coherent phase diagram and the precipitation kinetic model depend on the equilibrium phase diagram, the eigenstrain of the precipitating phase, and the chemical potential of point defects. From a joint experimental and modeling study, we uncover the prominent role of excess point defects in unforeseen phase transformations of the Fe–Ni metallic system under irradiation. By addressing the fundamental role of lattice point defects in the accommodation mechanisms of precipitation, we provide a step torwards the understanding of semi-coherent phase transformations occurring in solid materials upon synthesis and in use.

Calculation of the Liquidus Curves of CaO-Al2O3 Phase Diagram by ESTPHAD Method

2008 ◽  
Vol 589 ◽  
pp. 323-328
Author(s):  
Tamás Mende ◽  
András Roósz
Keyword(s):  
Phase Diagram ◽  
Measurement Error ◽  
Phase Diagrams ◽  
Equilibrium Phase ◽  
Equilibrium Phase Diagram ◽  
Measured Data ◽  
Calculation Time ◽  
Precise Result ◽  
Al2o3 Phase ◽  
The Given

Using the ESTPHAD (Estimation of Phase Diagrams) method, the liquidus and solidus curves in the equilibrium phase diagram can be created by thermodynamic based equations. By these determined equations, the liquidus or solidus temperatures as a function of concentration can be calculated with the required precision. The main advantages of the ESTPHAD method are as follows: the parameters of functions can be calculated simply, it gives a precise result and the calculation time is short. This paper shows the reconstruction of the liquidus curves of the CaO-Al2O3 phase diagram (0-60 wt% Al2O3 range) by using the ESTPHAD method on the basis of the measured data. The divergences between the measured and calculated (ESTPHAD) data are less than the given measurement error (±10 K).

Program Drawing the Dynamic Phase Diagrams of MnCrNiMo Type Steels

2014 ◽  
Vol 692 ◽  
pp. 444-449
Author(s):  
Qing Hua Zou ◽  
Li Zhu
Keyword(s):  
Phase Diagram ◽  
Phase Diagrams ◽  
Computer Calculation ◽  
Equilibrium Phase ◽  
Equilibrium Phase Diagram ◽  
Chemical Compositions ◽  
Type Steel ◽  
Dynamic Phase Diagrams ◽  
Dynamic Phase ◽  
Non Equilibrium

The dynamic phase diagrams of MnCrNiMo type steel have been established and discussed, which can be applied in the practical production, and it analyzes the corresponding structures and chemical compositions. The computer calculation and drawing programs of non-equilibrium phase diagram of MnCrNiMo type steel. having been designed

Sign in / Sign up

Export Citation Format

Share Document