Orientation Relations of Martensitic Transformations in FeMnCr Steels

2017 ◽  
Vol 885 ◽  
pp. 165-170
Author(s):  
Erzsebet Nagy ◽  
Márton Benke ◽  
Árpád Kovács ◽  
Valéria Mertinger
Keyword(s):  
Thermomechanical Treatment ◽  
Diffraction Method ◽  
Martensitic Transformations ◽  
Temperature Deformation ◽  
Thermally Induced ◽  
Crystallographic Anisotropy ◽  
Orientation Relations ◽  
Strain Induced Martensite ◽  
Twip Steels ◽  
Different Origins

The crystallographic orientation relations of phases forming during the martensitic transformation determine the properties of alloys. In TRIP/TWIP steels, the circumstances of thermomechanical treatment (e.g. temperature, deformation) define the forming of martensites of different origins. Due to the thermomechanical treatment, thermally induced martensite (εTH), strain induced martensite (εD) and α’ martensite phases are present in the samples besides the austenite. The proportion of martensites in the sample is defined by the parameters of treatment. The thermally and strain induced martensites which are simultaneously present in the alloy at room temperature can be differentiated by the orientation relations.The martensitic transformations were followed by different methods in FeMn alloys with different Cr content. The macroscopic crystallographic anisotropy was measured by X-ray diffraction method; the microscopic one was examined by EBSD. The cognition of phenomenon observed in the texture image in different scales helps determine the possible origin of martensites.

In Situ Optical Microscopic Examination Techniques of Thermally Induced Displacive Transformations

2015 ◽  
Vol 812 ◽  
pp. 279-284
Author(s):  
Márton Benke ◽  
Valéria Mertinger
Keyword(s):  
Thermal Transformation ◽  
Martensitic Transformations ◽  
Thermally Induced ◽  
Relief Formation ◽  
Twip Steels ◽  
Examination Techniques ◽  
Microscopy Method ◽  
Deformation Stress ◽  
Hysteresis Characteristics

The mechanical (reversible deformation, stress-strain diagrams, etc.) and thermal (transformation temperatures, hysteresis) characteristics of the thermoelastic martensitic transformations are in the focus of many manuscripts, however, other aspects of the transformations are given less attention. The relief formation accompanied with displacive transformations ensures the possibility of the direct observation of the mechanism and physical metallurgical characteristics of the martensite↔austenite transformations. The authors of the present manuscript applied the in situ optical microscopy method successfully using self-developed examination techniques and self-made heating stages to characterize the thermally induced displacive transformations in shape memory alloys (SMAs) and TWIP steels.

In situtransmission electron microscopy study of the thermally induced formation of δ′-ZrO in pure Zr and Zr-based alloy

2017 ◽  
Vol 50 (4) ◽  
pp. 1028-1035 ◽  
Author(s):  
Hongbing Yu ◽  
Zhongwen Yao ◽  
Fei Long ◽  
Peyman Saidi ◽  
Mark R. Daymond
Keyword(s):  
Electron Microscopy ◽  
Thin Foil ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Orientation Relationships ◽  
Thermally Induced ◽  
Thin Foils ◽  
Orientation Relations ◽  
Transmission Electron

This study reportsin situobservations of the formation of the δ′-ZrO phase, occurring during the annealing of transmission electron microscopy (TEM) thin foils of both pure Zr and a Zr–Sn–Nb–Mo alloy at 973 K in a transmission electron microsope. The lattice parameters of δ′-ZrO were measured and determined to be similar to those of the ω-Zr phase. The orientation relationship between the δ′-ZrO and α-Zr phases has been identified as either {(11 \overline{2}0)}_{\rm ZrO}//{(0002)}_{\alpha} and {[0002]}_{\rm ZrO}//{[11 \overline{2}0]}_{\alpha} or {(\overline{1}011)}_{\rm ZrO}//{(0002)}_{\alpha} and {[01{\overline 1}1]_{{\rm{ZrO}}}}//{[11{\overline 2}0]_\alpha} depending on the orientation of the α grain relative to the TEM thin-foil normal. The nucleation and growth of δ′-ZrO were dynamically observed. This study suggests a new and convenient way to study oxidation mechanisms in Zr alloys and provides a deeper understanding of the properties of the newly reported δ′-ZrO. Since δ′-ZrO has a Zr sublattice which is identical to that of ω-Zr, the orientation relationships between the α and δ′-ZrO phases may also shed light on the orientation relations existing between α- and ω-Zr, and hence α- and ω-Ti.

scholarly journals SHAPE ANALYSIS OF FINE AGGREGATES USED FOR CONCRETE

2016 ◽  
Vol 35 (3) ◽  
pp. 159 ◽  
Author(s):  
Huan He ◽  
Luc Courard ◽  
Eric Pirard ◽  
Frederic Michel
Keyword(s):  
Image Analysis ◽  
Coarse Aggregate ◽  
Diffraction Method ◽  
Crushed Rock ◽  
Fine Aggregate ◽  
River Sand ◽  
Fine Aggregates ◽  
Essential Components ◽  
Different Origins ◽  
Shape Characterization

Fine aggregate is one of the essential components in concrete and significantly influences the material properties. As parts of natures, physical characteristics of fine aggregate are highly relevant to its behaviors in concrete. The most of previous studies are mainly focused on the physical properties of coarse aggregate due to the equipment limitations. In this paper, two typical fine aggregates, i.e. river sand and crushed rock, are selected for shape characterization. The new developed digital image analysis systems are employed as the main approaches for the purpose. Some other technical methods, e.g. sieve test, laser diffraction method are also used for the comparable references. Shape characteristics of fine aggregates with different origins but in similar size ranges are revealed by this study. Compared with coarse aggregate, fine grains of different origins generally have similar shape differences. These differences are more significant in surface texture properties, which can be easily identified by an advanced shape parameter: bluntness. The new image analysis method is then approved to be efficient for the shape characterization of fine aggregate in concrete.

Stability of thermally-induced martensitic transformations in Bi-atomic lattices

2003 ◽  
Vol 112 ◽  
pp. 1203-1203 ◽  
Author(s):  
R. S. Elliott ◽  
J. A. Shaw ◽  
N. Triantafyllidis
Keyword(s):  
Martensitic Transformations ◽  
Thermally Induced ◽  
Atomic Lattices

scholarly journals Mechanical behavior and fractographic analysis of a TiNi alloy with various thermomechanical treatment

2019 ◽  
Vol 298 ◽  
pp. 00019 ◽  
Author(s):  
Anna Churakova ◽  
Anna Yudahina ◽  
Elina Kayumova ◽  
Nikita Tolstov
Keyword(s):  
Dislocation Density ◽  
Thermal Cycling ◽  
Thermomechanical Treatment ◽  
Martensitic Transformations ◽  
Coarse Grained ◽  
Tini Alloy ◽  
Phase Hardening ◽  
Cold Upsetting ◽  
Cycling Treatment ◽  
Ultrafine Grained

Influence of thermomechanical treatment (deformation, thermal cycling treatment in the temperature range of martensitic transformations B2-B19’) on the TiNi alloys’ mechanical behaviour and fracture was studied. Different states were considered, they are initial coarse-grained (CG), ultrafine-grained (UFG) after ECAP (with a grain size of 200 nm), the state after ECAP and cold upsetting by 30% - UFG state with high dislocation density. It was shown that thermal cycling causes some increase in dislocation density, strength and microhardness in all the states. Thermal cycling of UFG alloys allows forming the states with non-equilibrium grain boundaries, with additional dislocations of “phase hardening”. The nature of the fracture was analysed in the TiNi alloy in various states.

Acoustic Emission Avalanches in Martensitic Transitions: New Perspectives for the Problem of Source Location

2011 ◽  
Vol 172-174 ◽  
pp. 144-149 ◽  
Author(s):  
Eduard Vives ◽  
Daniel Enrique Soto Parra ◽  
Antoni Planes ◽  
Lluís Mañosa ◽  
Ricardo Romero ◽  
...  
Keyword(s):  
Finite Element ◽  
Acoustic Emission ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Spatial Resolution ◽  
Finite Element Methods ◽  
Simultaneous Detection ◽  
Martensitic Transformations ◽  
Barkhausen Noise ◽  
Thermally Induced

Different experimental procedures for the location of sources of Acoustic Emission (AE) avalanches during Martensitic Transformations are discussed. A first example corresponds to the 1D location of AE events during stress-induced martensitic transitions in a Cu-Zn-Al shape memory alloy (3.5 cm length). The obtained data allows monitoring of the interface advancement with a spatial resolution of less than 1 mm. Secondly, we discuss two different ideas that have significant potential for improving this resolution in the case of thermally induced transitions in small single crystalline samples (~1 cm): the use of elastodynamic simulations based on finite element methods and the simultaneous detection of AE and Barkhausen noise in ferromagnetic samples.

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