scholarly journals Features of the Phase Transformations in Sheets, Tubes and Welding Seams of the Alloy Zr–2.5%Nb

1997 ◽  
Vol 30 (1-2) ◽  
pp. 55-70 ◽  
Author(s):  
M. Isaenkova ◽  
Yu. Perlovich
Keyword(s):  
Phase Transformation ◽  
Phase Transformations ◽  
Strain Hardening ◽  
Arc Welding ◽  
Melting Zone ◽  
Main Attention ◽  
Tangential Stresses ◽  
Cold Rolled ◽  
Characteristic Features ◽  
Thermal Influence

By use of X-ray texture analysis characteristic features of phase transformations in sheets, tubes and welding seams of the Zr–2.5%Nb alloy were studied. Main attention was given to inhomogeneity of phase transformation development, connected with inhomogeneous distribution of strain hardening in grains with different crystallographic orientations. The typical manifestation of phase transformation inhomogeneity in cold-rolled sheets is a shift of the initial texture maximum to the region of increased strain hardening. In channel tubes in consequence of phase transformations α−β−α the texture component {112−0}〈101−0〉 gains, testifying that tangential stresses favour corresponding alignment of basal normals accompanied by absorption of grains with other orientations. Competition between recrystallization and phase transformation in conditions of heating was considered. As strain hardening increases, recrystallization prior to phase transformation becomes more probable, being predominant within α-grains of some orientations. Parallel development of recrystallization and phase transformation in the zone of thermal influence by arc welding of rolled sheets was considered. It was shown that, as the distance from the melting zone decreases, different combinations of these processes realize.

Heat capacities and enthalpies of fusion and transformation for solvates of some salts with dimethyl sulfoxide and dimethylformamide

1988 ◽  
Vol 53 (12) ◽  
pp. 3072-3079
Author(s):  
Mojmír Skokánek ◽  
Ivo Sláma
Keyword(s):  
Heat Capacity ◽  
Phase Transformation ◽  
Phase Transformations ◽  
Dimethyl Sulfoxide ◽  
Liquidus Temperature ◽  
Molar Heat Capacity ◽  
Solid Phase ◽  
Zinc Nitrate ◽  
Heat Capacities ◽  
Liquid Phases

Molar heat capacities and molar enthalpies of fusion of the solvates Zn(NO3)2 . 2·24 DMSO, Zn(NO3)2 . 8·11 DMSO, Zn(NO3)2 . 6 DMSO, NaNO3 . 2·85 DMSO, and AgNO3 . DMF, where DMSO is dimethyl sulfoxide and DMF is dimethylformamide, have been determined over the temperature range 240 to 400 K. Endothermic peaks found for the zinc nitrate solvates below the liquidus temperature have been ascribed to solid phase transformations. The molar enthalpies of the solid phase transformations are close to 5 kJ mol-1 for all zinc nitrate solvates investigated. The dependence of the molar heat capacity on the temperature outside the phase transformation region can be described by a linear equation for both the solid and liquid phases.

Calculations of Phase Transformations in Welding Simulations

2014 ◽  
Vol 611 ◽  
pp. 46-53 ◽  
Author(s):  
Ladislav Novotný ◽  
Vladimír Ivančo
Keyword(s):  
Heat Flux ◽  
Phase Transformation ◽  
Boundary Conditions ◽  
Phase Transformations ◽  
Diffusion Processes ◽  
Transient Solution ◽  
Welding Simulation

In the paper the principle of welding simulation is presented and the methods of solution of phase transformation are described. The first part characterizes elementary equations of heat transient solution, boundary conditions during welding simulation (prescribing moving heat flux, convection, radiation). The methods of phase transformations’ solution are described for diffusion processes as well as diffusionless processes.

Influence of Phase Transformations on Residual Stresses in Welded Structures

2013 ◽  
Author(s):  
R. J. Dennis ◽  
R. Kulka ◽  
O. Muransky ◽  
M. C. Smith
Keyword(s):  
Phase Transformation ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Numerical Models ◽  
Material Model ◽  
Transformation Model ◽  
Austenitic Steels ◽  
Beam Specimen ◽  
Welded Structures ◽  
The Impact

A key aspect of any numerical simulation to predict welding induced residual stresses is the development and application of an appropriate material model. Often significant effort is expended characterising the thermal, physical and hardening properties including complex phenomena such as high temperature annealing. Consideration of these aspects is sufficient to produce a realistic prediction for austenitic steels, however ferritic steels are susceptible to solid state phase transformations when heated to high temperatures. On cooling a reverse transformation occurs, with an associated volume change at the isothermal transformation temperature. Although numerical models exist (e.g. Leblond) to predict the evolution of the metallurgical phases, accounting for volumetric changes, it remains a matter of debate as to the magnitude of the impact of phase transformations on residual stresses. Often phase transformations are neglected entirely. In this work a simple phase transformation model is applied to a range of welded structures with the specific aim of assessing the impact, or otherwise, of phase transformations on the magnitude and distribution of predicted residual stresses. The welded structures considered account for a range of geometries from a simple ferritic beam specimen to a thick section multi-pass weld. The outcome of this work is an improved understanding of the role of phase transformation on residual stresses and an appreciation of the circumstances in which it should be considered.

Insight into microstructural and phase transformations in electrochemical sodiation–desodiation of a bismuth particulate anode

2017 ◽  
Vol 5 (40) ◽  
pp. 21536-21541 ◽  
Author(s):  
Chek-Hai Lim ◽  
Baskar Selvaraj ◽  
Yen-Fang Song ◽  
Chun-Chieh Wang ◽  
Jian-Ting Jin ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Phase Transformations ◽  
X Ray ◽  
In Operando ◽  
Delayed Phase ◽  
Insight Into

In operando synchrotron X-ray analyses reveal unique delayed phase transformation and particle fracturing processes of a Bi anode for Na-ion batteries.

scholarly journals Characteristic Features of the Phase Transformation in In-Hg Alloys

1983 ◽  
Vol 47 (8) ◽  
pp. 655-662
Author(s):  
Yasumasa Koyama ◽  
Hiroyuki Suzuki ◽  
Osamu Nittono
Keyword(s):  
Phase Transformation ◽  
Characteristic Features

scholarly journals Inhomogeneity of Phase Transformations β→ω and β→α in the Quenched Cold-Rolled Alloy Zr-20 %Nb

1996 ◽  
Vol 06 (C1) ◽  
pp. C1-149-C1-156 ◽  
Author(s):  
Yu. Perlovich ◽  
H. J. Bunge ◽  
V. Fesenko ◽  
M. Isaenkova ◽  
N. J. Park ◽  
...  
Keyword(s):  
Phase Transformations ◽  
Cold Rolled

Modeling Phase Transformation Kinetics and Their Effect on Hardness and Hardness Depth in Laser Hardening of Hypoeutectoid Steel

2015 ◽  
Author(s):  
Suhash Ghosh ◽  
Chittaranjan Sahay
Keyword(s):  
Thermal Analysis ◽  
Phase Transformation ◽  
Phase Transformations ◽  
Laser Hardening ◽  
Temperature History ◽  
Transformation Kinetics ◽  
Continuous Cooling ◽  
Phase Transformation Kinetics ◽  
Hardness Depth ◽  
Hypoeutectoid Steel

Much research has been done to model laser hardening phase transformation kinetics. In that research, assumptions are made about the austenization of the steel that does not translate into accurate hardness depth calculations. The purpose of this paper is to develop an analytical method to accurately model laser hardening phase transformation kinetics of hypoeutectoid steel, accounting for non-homogeneous austenization. The modeling is split into two sections. The first models the transient thermal analysis to obtain temperature time-histories for each point in the workpiece. The second models non-homogeneous austenization and utilizes continuous cooling curves to predict microstructure and hardness. Non-homogeneous austenization plays a significant role in the hardness and hardness depth in the steel. A finite element based three-dimensional thermal analysis in ANSYS is performed to obtain the temperature history on three steel workpieces for laser hardening process with no melting; AISI 1030, 1040 and 1045 steels. This is followed by the determination of microstructural changes due to ferrite and pearlite transformation to austenite during heating and the subsequent austenite to martensite and other diffusional transformations during cooling. Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation is used to track the phase transformations during heating, including the effects of non-homogenous austenitization. The solid state nodal phase transformations during cooling are monitored on the material’s digitized Continuous Cooling Transformation (CCT) curve through a user defined input file in ANSYS for all cooling rates within the Heat Affected Zone (HAZ). Material non-linearity is included in the model by including temperature dependent thermal properties for the material. The model predictions for hardness underneath the laser and the HAZ match well with the experimental results published in literature.

Atomic-scale understanding of stress-induced phase transformation in cold-rolled Hf

2017 ◽  
Vol 131 ◽  
pp. 271-279 ◽  
Author(s):  
Henglv Zhao ◽  
Min Song ◽  
Song Ni ◽  
Shuai Shao ◽  
Jian Wang ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Atomic Scale ◽  
Cold Rolled
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