WITHDRAWN: Relationship between austenite grain size, martensite start temperature, and transformation kinetics of AISI 4340 steel

2006 ◽  
Author(s):  
Seok-Jae Lee ◽  
Yong-Min Park ◽  
Young-Kook Lee
Keyword(s):  
Grain Size ◽  
Transformation Kinetics ◽  
Austenite Grain Size ◽  
Aisi 4340 Steel ◽  
Austenite Grain ◽  
4340 Steel ◽  
Kinetics Of ◽  
Start Temperature ◽  
Aisi 4340

scholarly journals A New Systematic Approach Based on Dilatometric Analysis to Track Bainite Transformation Kinetics and the Influence of the Prior Austenite Grain Size

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 324
Author(s):  
David San-Martin ◽  
Matthias Kuntz ◽  
Francisca G. Caballero ◽  
Carlos Garcia-Mateo
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Prior Austenite ◽  
Bainitic Transformation ◽  
Transformation Rate ◽  
Transformation Kinetics ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Prior Austenite Grain Size ◽  
Prior Austenite Grain

This investigation explores the influence of the austenitisation heat treatment and thus, of the prior austenite grain size (PAGS), on the kinetics of the bainitic transformation, using as A case study two high-carbon, high-silicon, bainitic steels isothermally transformed (TIso = 250, 300, 350 °C), after being austenised at different temperatures (γTγ = 925–1125 °C). A methodology, based on the three defining dilatometric parameters extracted from the derivative of the relative change in length, was proposed to analyse the transformation kinetics. These parameters are related to the time to start bainitic transformation, the time lapse for most of the transformation to take place and the transformation rate at the end of the transformation. The results show that increasing the PAGS up to 70 µm leads to an increase in the bainite nucleation rate, this effect being more pronounced for the lowest TIso. However, the overall transformation kinetics seems to be weakly affected by the applied heat treatment (γTγ and TIso). In one of the steels, PAGS > 70 µm (γTγ > 1050 °C), which weakly affects the progress of the transformation, except for TIso = 250 °C, for which the enhancement of the autocatalytic effect could be the reason behind an acceleration of the overall transformation.

Alloying Effects on Reverse Transformation to Austenite from Pearlite or Tempered Martensite Structures

2010 ◽  
Vol 638-642 ◽  
pp. 3400-3405 ◽  
Author(s):  
Goro Miyamoto ◽  
Zhao Dong Li ◽  
Hirokazu Usuki ◽  
Tadashi Furuhara
Keyword(s):  
Decomposition Reaction ◽  
Reverse Transformation ◽  
Transformation Kinetics ◽  
Tempered Martensite ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Cr Addition ◽  
Alloying Effects ◽  
Kinetics Of ◽  
Martensite Structure

Reverse transformation has been frequently used to refine austenite grain size for refining ferrite, pearlite and martensite structures. However, kinetics and microstructure change during reverse transformation to austenite has not been examined systematically compared with the austenite decomposition reaction. Therefore, alloying effects of 1mass% Mn, Si and Cr on reverse transformation kinetics from pearlite and tempered martensite structures in Fe-0.6mass%C alloys were investigated in this study. Vickers hardness of all the specimens increases with increasing holding time at 1073K because reversely-formed austenite transforms to martensite by quenching. In the reverse transformation from pearlite structure, the kinetics of reverse transformation is hardly changed by the Mn addition while Si and Cr additions delay it. Kinetics of reverse transformation from tempered martensite structure becomes slower than from the pearlite structure in all the alloys. In particular, retarding effect by the Cr addition is most significant among those elements.

scholarly journals Dependence of martensite start temperature on fine austenite grain size

2008 ◽  
Vol 58 (2) ◽  
pp. 134-137 ◽  
Author(s):  
A. García-Junceda ◽  
C. Capdevila ◽  
F.G. Caballero ◽  
C. García de Andrés
Keyword(s):  
Grain Size ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Start Temperature

Calibrating Phase Transformation and Grain Growth Models and Measuring Phase Dependent Material Properties for Use in FE Simulations of Welds

2015 ◽  
Author(s):  
Nicholas O’Meara ◽  
Simon D. Smith ◽  
John A. Francis
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Prior Austenite ◽  
Computer Modelling ◽  
Transformation Model ◽  
Transformation Kinetics ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Prior Austenite Grain Size ◽  
Prior Austenite Grain

Computer modelling methods are being used to determine the residual stresses in nuclear reactor pressure vessel welds. It has been found that such models need to simulate the effects of solid state phase transformations. Transformations have an associated transformation strain which can significantly influence the evolution of residual stress. The predicted distribution of phases enables structural simulations to account for the distribution of mechanical properties throughout a weld. Factors such as heating or cooling rate and prior austenite grain size must be considered in order to accurately predict the distribution of phases during a transient thermal cycle since they influence transformation kinetics. In this paper, a model to predict the prior austenite grain size and its effects on phase transformation kinetics is presented and calibrated using free dilatometry data. Validation experiments are conducted using a Gleeble thermo-mechanical simulator and are modelled in a commercial FE package to assess the accuracy of a phase transformation model. Samples have been heat treated to possess specific microstructures and have been tested at different temperatures to establish the properties of the phases that can form during weld thermal cycles.

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