Quantitative Analysis of Variant Selection and Orientation Relationships during the γ-to-α Phase Transformation in Hot-Rolled TRIP Steels

2010 ◽  
Vol 89-91 ◽  
pp. 359-364 ◽  
Author(s):  
Loïc Malet ◽  
Pascal J. Jacques ◽  
Stéphane Godet

The orientation relationships that apply to the fcc (γ) – bcc (α) phase transformation in high-performance hot-rolled TRIP-aided steels were characterised by EBSD techniques. A statistical treatment of the experimental data allows the mean orientation relationship to be determined. This mean orientation relationship was compared to the models commonly proposed in the literature and confronted qualitatively to the predictions of the phenomenological theory of martensite crystallography (PTMC). The variant selection phenomenon was also characterized quantitatively at the level of individual austenite grains. The reconstruction of the EBSD maps evidences that bainite grows by packets in which the bainite laths share a common {111}γ plane in the austenite. This growth mechanism is not influenced by the prior hot deformation of the austenite. The hot deformation has a critical influence on the number of packets that forms. The analysis of the crystallographic features of the bainite packets reveals that all possible variants are formed in a packet, though in different proportions.

2017 ◽  
Vol 29 (7) ◽  
pp. 3246-3250 ◽  
Author(s):  
Tanghao Liu ◽  
Yingxia Zong ◽  
Yuanyuan Zhou ◽  
Mengjin Yang ◽  
Zhen Li ◽  
...  

2006 ◽  
Vol 979 ◽  
Author(s):  
Xiao Ma ◽  
R.C. Pond

AbstractOur current understanding of martensitic transformations has been based on the Phenomenological Theory of Martensite Crystallography developed in the 1950s. Recently, a Topological Model of martensitic transformations has been presented wherein the habit plane is a semi-coherent structure, and the transformation mechanism is shown explicitly to be diffusionless. This approach is used here to model phase transformation crystallography of lath martensite in ferrous alloys. A range of network geometries is predicted corresponding to orientation relationships varying from Nishiyama-Wasserman to Kurdjumov-Sachs. Experimental observations from the literature of the dislocation and disconnection arrays, habit plane and orientation relationship are in good agreement with the model.


2012 ◽  
Vol 60 (17) ◽  
pp. 6013-6024 ◽  
Author(s):  
G.C. Obasi ◽  
S. Birosca ◽  
D.G. Leo Prakash ◽  
J. Quinta da Fonseca ◽  
M. Preuss

2017 ◽  
Vol 50 (6) ◽  
pp. 1646-1652 ◽  
Author(s):  
Annick P. Baur ◽  
Cyril Cayron ◽  
Roland E. Logé

A significant variant selection is reported in isothermal martensite formed on the surface of an Fe–30% Ni sample. The selection phenomenon is modelled using different descriptions of the martensitic phase transformation. In particular, matrices based on the phenomenological theory of martensite crystallography, the Jaswon and Wheeler distortion, and the continuous face centred cubic–body centred cubic distortion are compared. All descriptions allow good predictions of the variant selection. However, the Jaswon and Wheeler distortion and the continuous distortion better account for other features of the surface martensite, such as the {225}γhabit plane and the accommodation mechanism by twin-related variant pairing.


2011 ◽  
Vol 8 (1) ◽  
pp. 103066 ◽  
Author(s):  
P. Mosbrucker ◽  
M. R. Daymond ◽  
R. A. Holt ◽  
P. Barberis ◽  
S. W. Dean

1999 ◽  
Vol 32 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Michel Humbert ◽  
Nathalie Gey

Different factors calculated from theCcoefficients of the inherited orientation distribution function (ODF) allow us to check the importance of the variant selection. When no variant selection or a slight variant selection occurs by the cubic-to-hexagonal phase transformation, it is possible to calculate the ODF of the cubic parent phase present at high temperature from the ODF of the inherited hexagonal phase at room temperature. When a stronger variant selection occurs, qualitative information about the parent ODF can be obtained by using a specific correlation function, which we have named R(g).


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