The Experts below are selected from a list of 1689 Experts worldwide ranked by ideXlab platform
Edward B. Damm - One of the best experts on this subject based on the ideXlab platform.
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Monitoring Austenite Decomposition by ultrasonic velocity
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: S. E. Kruger, Edward B. DammAbstract:The ultrasonic longitudinal velocity measured by the laser-ultrasonic technique is compared to dilatometry for the monitoring of Austenite Decomposition of low alloy steels. It is demonstrated that the technique could be an interesting alternative to dilatometry. The temperature dependence of the ultrasonic velocity and the various phases in steels is determined and used to calculate the decomposed Austenite by a simple law of mixtures approximation. As a non-destructive and non-contact technique, laser-ultrasonics can be applied to monitor Austenite transformation of real products in an industrial production line, which would be much more difficult with dilatometry.
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Monitoring Austenite Decomposition by ultrasonic velocity
Materials Science and Engineering: A, 2006Co-Authors: S. E. Kruger, Edward B. DammAbstract:The ultrasonic longitudinal velocity measured by the laser-ultrasonic technique is compared to dilatometry for the monitoring of Austenite Decomposition of low alloy steels. It is demonstrated that the technique could be an interesting alternative to dilatometry. The temperature dependence of the ultrasonic velocity and the various phases in steels is determined and used to calculate the decomposed Austenite by a simple law of mixtures approximation. As a non-destructive and non-contact technique, laser-ultrasonics can be applied to monitor Austenite transformation of real products in an industrial production line, which would be much more difficult with dilatometry.Peer reviewed: YesNRC publication: Ye
S. E. Kruger - One of the best experts on this subject based on the ideXlab platform.
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Monitoring Austenite Decomposition by ultrasonic velocity
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: S. E. Kruger, Edward B. DammAbstract:The ultrasonic longitudinal velocity measured by the laser-ultrasonic technique is compared to dilatometry for the monitoring of Austenite Decomposition of low alloy steels. It is demonstrated that the technique could be an interesting alternative to dilatometry. The temperature dependence of the ultrasonic velocity and the various phases in steels is determined and used to calculate the decomposed Austenite by a simple law of mixtures approximation. As a non-destructive and non-contact technique, laser-ultrasonics can be applied to monitor Austenite transformation of real products in an industrial production line, which would be much more difficult with dilatometry.
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Monitoring Austenite Decomposition by ultrasonic velocity
Materials Science and Engineering: A, 2006Co-Authors: S. E. Kruger, Edward B. DammAbstract:The ultrasonic longitudinal velocity measured by the laser-ultrasonic technique is compared to dilatometry for the monitoring of Austenite Decomposition of low alloy steels. It is demonstrated that the technique could be an interesting alternative to dilatometry. The temperature dependence of the ultrasonic velocity and the various phases in steels is determined and used to calculate the decomposed Austenite by a simple law of mixtures approximation. As a non-destructive and non-contact technique, laser-ultrasonics can be applied to monitor Austenite transformation of real products in an industrial production line, which would be much more difficult with dilatometry.Peer reviewed: YesNRC publication: Ye
Mats Oldenburg - One of the best experts on this subject based on the ideXlab platform.
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Austenite Decomposition during press hardening of a boron steel computer simulation and test
Journal of Materials Processing Technology, 2006Co-Authors: Paul Akerstrom, Mats OldenburgAbstract:In this work a model to predict the Austenite Decomposition into ferrite, pearlite, bainite and martensite during arbitrary cooling paths for thin sheet boron steel is used. The model is based on K ...
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Austenite Decomposition during press hardening of a boron steel computer simulation and test
Journal of Materials Processing Technology, 2006Co-Authors: Paul Akerstrom, Mats OldenburgAbstract:Abstract In this work a model to predict the Austenite Decomposition into ferrite, pearlite, bainite and martensite during arbitrary cooling paths for thin sheet boron steel is used. The model is based on Kirkaldy’s rate equations. The basic rate equations has been modified to account for the Austenite stabilization effect from the added boron. The model is implemented as part of a material subroutine in the Finite Element Program LS-DYNA 970. Both the obtained simulated volume fractions microconstituents and hardness profiles shows promising agreement to the corresponding experimental observations.
Matthias Militzer - One of the best experts on this subject based on the ideXlab platform.
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The Effect of Niobium on Austenite Decomposition in Line Pipe Steels
Volume 3: Operations Monitoring and Maintenance; Materials and Joining, 2016Co-Authors: I. D. G. Robinson, Thomas Garcin, Warren J. Poole, Matthias MilitzerAbstract:Niobium is a common micro-alloying addition in high-strength low-alloy (HSLA) steels primarily to add strength to the final product. Detailed quantification of the various effects of niobium is critical for understanding the microstructure evolution in the heat affected zone (HAZ) of welds. Laser ultrasonics for metallurgy (LUMet) was used to measure Austenite grain growth kinetics in two experimental HSLA steels during continuous heating. For higher heating rates that are of relevance for the HAZ, grain growth during heating is negligible and grain size is determined during the brief time at the peak temperature. Thermal histories were designed based on these tests to produce a variety of microstructures relevant for various positions in the HAZ i.e. coarse and fine grain regions. It was found that the dissolution of niobium carbonitrides has a strong effect on Austenite Decomposition, particularily in the case of large Austenite grain sizes. Nb in solution significantly depresses transformation temperatures in refinement of bainitic microstructures, significantly increasing the hardness in the coarse grained HAZ.
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formation of martensite Austenite m a in x80 linepipe steel
2012 9th International Pipeline Conference, 2012Co-Authors: Jennifer M Reichert, Thomas Garcin, Matthias Militzer, W J PooleAbstract:Linepipe steels are usually microalloyed with Nb to promote the formation of complex microstructures that lead to the required mechanical properties. In particular, Nb in solution affects significantly the Austenite Decomposition kinetics and the resulting microstructure. A systematic study has been carried out to quantify the influence of Nb on the Austenite Decomposition kinetics in X80 linepipe steel. Continuous cooling transformation tests were conducted with a Gleeble 3500. The transformation products include ferrite, granular and upper bainite and M/A (martensite/ retained Austenite) constituents. For this study optical microscopy was used to investigate the formation of M/A constituents that critically determine the fracture toughness. A relation between M/A and the surrounding microstructure is observed. In combination with an existent model for the prediction of the microstructure evolution during weld thermal cycles, the area fraction, size and morphology of M/A can be predicted for the simulated HAZ, based on the prior Austenite grain size, cooling rate and amount of Nb in solution.Copyright © 2012 by ASME
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Formation of Martensite/Austenite (M/A) in X80 Linepipe Steel
Volume 3: Materials and Joining, 2012Co-Authors: Jennifer M Reichert, Thomas Garcin, Matthias Militzer, Warren J. PooleAbstract:Linepipe steels are usually microalloyed with Nb to promote the formation of complex microstructures that lead to the required mechanical properties. In particular, Nb in solution affects significantly the Austenite Decomposition kinetics and the resulting microstructure. A systematic study has been carried out to quantify the influence of Nb on the Austenite Decomposition kinetics in X80 linepipe steel. Continuous cooling transformation tests were conducted with a Gleeble 3500. The transformation products include ferrite, granular and upper bainite and M/A (martensite/ retained Austenite) constituents. For this study optical microscopy was used to investigate the formation of M/A constituents that critically determine the fracture toughness. A relation between M/A and the surrounding microstructure is observed. In combination with an existent model for the prediction of the microstructure evolution during weld thermal cycles, the area fraction, size and morphology of M/A can be predicted for the simulated HAZ, based on the prior Austenite grain size, cooling rate and amount of Nb in solution.Copyright © 2012 by ASME
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Towards an Austenite Decomposition model for TRIP steels
Steel Research, 2002Co-Authors: Fateh Fazeli, Matthias MilitzerAbstract:The current status of developing a fundamental model for describing the overall Austenite Decomposition kinetics to ferrite and carbide-free bainite in low carbon TRIP steels alloyed with Mn and Si is reviewed. For ferrite growth, a model is proposed where both interface and carbon diffusion-controlled ferrite formation are considered in a mixed-mode approach. The kinetic model is coupled with Thermocalc to obtain necessary thermodynamic information. Spherical geometry with an outer ferrite shell is assumed to capture in a simple way the topological conditions for growth. The mixed-mode modelling philosophy has been identified to permit a rigorous incorporation of the solute drag effect of substitutional alloying elements, in particular Mn. The Purdy-Brechet solute drag theory is adopted to characterize the interaction of Mn with the moving Austenite-ferrite interface. The challenges of quantifying the required solute drag parameters are discussed with an emphasis on a potential solute drag interaction of Mn and Si. The model is extended to non-isothermal processing paths to account for continuous and stepped cooling occurring on the run-out table of a hot strip mill or on a continuous annealing line. The transformation start temperature during cooling is predicted with a model combining nucleation and early growth which had previously been validated for conventional low carbon steels. The overall model is evaluated by comparing the predictions with experimental data for the ferrite growth kinetics during continuous cooling of a classical TRIP steel with mass contents of 0.19 % C, 1.49 % Mn and 1.95 % Si. Extension of the model to include bainite formation remains a challenge. Both diffusional and displacive model approaches are discussed for the formation of carbide-free bainite. It is suggested to develop a combined nucleation and growth model which would enable to capture a potential transition from a diffusional to a displacive transformation mode with decreasing temperature.
W J Poole - One of the best experts on this subject based on the ideXlab platform.
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formation of martensite Austenite m a in x80 linepipe steel
2012 9th International Pipeline Conference, 2012Co-Authors: Jennifer M Reichert, Thomas Garcin, Matthias Militzer, W J PooleAbstract:Linepipe steels are usually microalloyed with Nb to promote the formation of complex microstructures that lead to the required mechanical properties. In particular, Nb in solution affects significantly the Austenite Decomposition kinetics and the resulting microstructure. A systematic study has been carried out to quantify the influence of Nb on the Austenite Decomposition kinetics in X80 linepipe steel. Continuous cooling transformation tests were conducted with a Gleeble 3500. The transformation products include ferrite, granular and upper bainite and M/A (martensite/ retained Austenite) constituents. For this study optical microscopy was used to investigate the formation of M/A constituents that critically determine the fracture toughness. A relation between M/A and the surrounding microstructure is observed. In combination with an existent model for the prediction of the microstructure evolution during weld thermal cycles, the area fraction, size and morphology of M/A can be predicted for the simulated HAZ, based on the prior Austenite grain size, cooling rate and amount of Nb in solution.Copyright © 2012 by ASME
