Characterization of (α+β)/β Transformation in a TC11 Titanium Alloy

2007 ◽  
Vol 127 ◽  
pp. 91-96 ◽  
Author(s):  
Lin Geng ◽  
Bin Xu ◽  
Y.T. Li ◽  
Ai Bin Li ◽  
Gui Song Wang
Keyword(s):  
Titanium Alloy ◽  
Phase Transformation ◽  
Transformation Temperature ◽  
Annealing Treatment ◽  
Phase Transformation Temperature ◽  
Scanning Calorimetry ◽  
Β Phase ◽  
Before And After ◽  
Forming Temperature ◽  
Tc11 Titanium Alloy

(α+β)/β phase transformation temperature of a TC11 titanium alloy was confirmed to be 1035°C, which was obtained by three methods including the calculation method, differential scanning calorimetry and metallographic techniques. Based on this result, annealing treatments below and above the (α+β)/β phase transformation temperature were carried out, and the microstructure of the TC11 alloys before and after annealing treatment was analyzed by SEM. The result showed that conventional annealing below 1035°C does not change the Widmanstaten structure of TC11 alloy, though the thickness of α lamellar structure becomes thicker with increasing the annealing temperature. The microstructure of the TC11 alloy treated by annealing above the α+β/β transformation temperature is non-uniform because of the different forming temperature and growing duration of α phase in the TC11 alloy.

Thermodynamics of the tetragonal-to-monoclinic phase transformation in fine and nanocrystalline yttria-stabilized zirconia powders

2003 ◽  
Vol 18 (12) ◽  
pp. 2912-2921 ◽  
Author(s):  
Arun Suresh ◽  
Merrilea J. Mayo ◽  
Wallace D. Porter
Keyword(s):  
Particle Size ◽  
Phase Transformation ◽  
Transformation Temperature ◽  
Phase Transformation Temperature ◽  
Scanning Calorimetry ◽  
Fine Grained ◽  
Dopant Level ◽  
M Phase ◽  
Additional Strain ◽  
Enthalpy And Entropy Changes

The current study uses high-temperature differential scanning calorimetry to document the shift in phase-transformation temperature with particle size throughout a series of alloys in the zirconia–yttria system (0–1.5 mol% yttria). The tetragonal-to-monoclinic (T→M) phase-transformation temperature is seen to vary inversely with particle size. It is shown that a simple thermodynamic approach first proposed by Garvie predicts this inverse linear relationship. Subsequent determination of the key thermodynamic parameters therein (e.g., the surface and volume free energy, enthalpy, and entropy changes involved in the phase transformation) allows a complete predictive equation for the T→M phase transformation in the yttria–zirconia system to be developed as a function of particle size and yttria dopant level. The yttria–zirconia phase diagram is then redrawn with grain size as a third variable. It should be stressed that the current analysis is valid for particulate systems only; a parallel paper tackles the problem for fine-grained yttria–zirconia solids, where the approach is similar, but additional strain energy terms come into play.

Determination of Transformation Temperatures of SMAs by Varying the Force Using Dead Weight Method

2015 ◽  
Vol 813-814 ◽  
pp. 166-171
Author(s):  
Kiran D. Jadhav ◽  
U.S. Mallikarjun ◽  
S.H. Adarsh ◽  
S. Prashantha
Keyword(s):  
Phase Transformation ◽  
Shape Memory ◽  
Transformation Temperature ◽  
Phase Transformation Temperature ◽  
Scanning Calorimetry ◽  
Dead Weight ◽  
Strain Behavior ◽  
Weight Method ◽  
Nitinol Alloy ◽  
Dsc Method

Shape-memory material is an alloy that “Remembers” its original shape and that when deformed to its Pre-deformed shape when heated. Phase transformation temperature is one of the most important parameters for the shape memory alloys. In this present work phase transformation temperature is measured by the dead weight method and compared with standard Differential scanning calorimetry (DSC) method. The objective of this paper is to study the microstructure of the Shape memory alloy (SMA) wire, determining the Phase Transformation temperature of NiTinol alloy i.e. Marteniste start (Ms), Martensite finish (Mf), Austenite Start (As), Austenite finish (Af) by a Dead Weight method and also studying the stress-strain behavior with variation of Temperatures to show the Shape memory effect in the NiTinol SMA wire.

Capability of martensitic low transformation temperature welding consumables for increasing the fatigue strength of high strength steel joints

2020 ◽  
Vol 62 (9) ◽  
pp. 891-900
Author(s):  
Jonas Hensel ◽  
Arne Kromm ◽  
Thomas Nitschke-Pagel ◽  
Jonny Dixneit ◽  
Klaus Dilger
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Fatigue Strength ◽  
High Strength Steel ◽  
Transformation Temperature ◽  
Fatigue Cracks ◽  
High Strength ◽  
Filler Material ◽  
Phase Transformation Temperature ◽  
Filler Materials

Abstract The use of low transformation temperature (LTT) filler materials represents a smart approach for increasing the fatigue strength of welded high strength steel structures apart from the usual procedures of post weld treatment. The main mechanism is based on the effect of the low start temperature of martensite formation on the stress already present during welding. Thus, compressive residual stress formed due to constrained volume expansion in connection with phase transformation become highly effective. Furthermore, the weld metal has a high hardness that can delay the formation of fatigue cracks but also leads to low toughness. Fundamental investigations on the weldability of an LTT filler material are presented in this work, including the characterization of the weld microstructure, its hardness, phase transformation temperature and mechanical properties. Special attention was applied to avoid imperfections in order to ensure a high weld quality for subsequent fatigue testing. Fatigue tests were conducted on the welded joints of the base materials S355J2 and S960QL using conventional filler materials as a comparison to the LTT filler. Butt joints were used with a variation in the weld type (DY-weld and V-weld). In addition, a component-like specimen (longitudinal stiffener) was investigated where the LTT filler material was applied as an additional layer. The joints were characterized with respect to residual stress, its stability during cyclic loading and microstructure. The results show that the application of LTT consumables leads to a significant increase in fatigue strength when basic design guidelines are followed. This enables a benefit from the lightweight design potential of high-strength steel grades.

Phase Transformation Temperature of NiTi Alloy Sheet Examined by Lamb Wave

2011 ◽  
Vol 320 ◽  
pp. 359-362
Author(s):  
Kai Sheng Wang ◽  
Ru Hui He ◽  
Zhi Min Zhao
Keyword(s):  
Phase Transformation ◽  
Lamb Wave ◽  
Transformation Temperature ◽  
Lamb Waves ◽  
Niti Alloy ◽  
Alloy Sheet ◽  
Phase Transformation Temperature ◽  
Wave Method

In this study, the ultrasonic PZT transducers were used for exciting and receiving Lamb waves on NiTi alloy sheet. Lamb waves were measured when the temperature of the NiTi alloy changed. Analysis on frequency spectrums of the Lamb waves was also done. Some marked changes were observed in the dependence of the waveforms and the frequency spectrums of the Lamb waves versus temperature during phase transformation of NiTi alloy. The results show that phase transformation temperature of NiTi alloy sheet may be examined by Lamb wave method.

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