scholarly journals The strain variation during the isothermal B2→B19’ martensitic transformation in the quenched or annealed Ni51Ti49 alloy

2022 ◽  
Vol 1213 (1) ◽  
pp. 012005
Author(s):  
A Ivanov ◽  
A Gabrielian ◽  
S Belyaev ◽  
N Resnina ◽  
V Andreev
Keyword(s):  
Martensitic Transformation ◽  
Volume Fraction ◽  
Isothermal Holding ◽  
Isothermal Transformation ◽  
Annealed Sample ◽  
Strain Variation ◽  
Maximum Value ◽  
Niti Phase ◽  
Alloy Heat ◽  
Isothermal Martensitic Transformation

Abstract The strain variation during the isothermal holding under constant stress was studied in the quenched or annealed Ni51Ti49 alloy samples. The isothermal strain variation was found in both samples and this strain was completely recovered on subsequent unloading and heating. This allowed to conclude that the strain variation on holding was caused by the isothermal martensitic transformation. It was found that the maximum value of isothermal strain depended on the alloy heat treatment. This value was equal to 0.5 % in annealed sample and it was equal to 6 % in quenched sample. It was assumed that the formation of the Ni4Ti3 phase during annealing led to a decrease in concentration of substitutional Ni atoms in NiTi phase that were responsible for the isothermal transformation. As a result, the less volume fraction of the martensite formed during holding that supresses the strain variation in annealed samples.

scholarly journals Influence of annealing on the functional properties of the NiTi alloy produced by wire arc additive manufacturing

2022 ◽  
Vol 1213 (1) ◽  
pp. 012002
Author(s):  
N Resnina ◽  
I A Palani ◽  
S Belyaev ◽  
R Bikbaev ◽  
Shalini Singh ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Martensitic Transformation ◽  
Annealing Temperature ◽  
Volume Fraction ◽  
Niti Alloy ◽  
Strain Variation ◽  
Recoverable Strain ◽  
Niti Phase ◽  
Working Length ◽  
Wire Arc Additive Manufacturing

Abstract The influence of the annealing temperature on the recoverable strain variation on cooling and heating under a stress of 200 MPa was studied in the NiTi samples produced by wire arc additive manufacturing. The samples including the Ni-rich NiTi layer in the working length were annealed for 10 hours at various temperature from 450 to 600 °C. It is shown that an increase in annealing temperature leads to non-monontonic variation in the recoverable strain. This is caused by an increase in annealing temperature from 450 to 550 °C increases the volume fraction of Ni4Ti3 precipitates. As a result, the volume fraction of the NiTi phase undergoing the martensitic transformation and recoverable strain decrease. An increase in annealing temperature from 550 to 600 °C leads to a dissolving the Ni4Ti3 precipitates and formation of the Ni3Ti2 precipitates that increases the volume fraction of the NiTi phase and the recoverable strain.

scholarly journals Strain variation in the Ti40,7Hf9,5Ni41,8Cu8 alloy during isothermal martensitic transformation under a constant stress

2022 ◽  
Vol 1213 (1) ◽  
pp. 012007
Author(s):  
E Demidova ◽  
P Pchelnikov ◽  
S Belyaev ◽  
N Resnina ◽  
A Shelyakov
Keyword(s):  
Martensitic Transformation ◽  
Constant Stress ◽  
Strain Variation ◽  
Maximum Value ◽  
Optimal Value ◽  
Isothermal Martensitic Transformation ◽  
Holding Temperature

Abstract Strain variation on holding under a constant stress was studied in the Ti40,7Hf9,5Ni41,8Cu8 alloy. It was found, that on holding under stress, the isothermal strain rose up to saturation, which value depended on holding temperature and stress. It was found that the dependencies of the isothermal strain on the holding temperature and stress were non-monotonic. This allowed to find the optimal value of stress and time at which the isothermal strain attained the maximum value of 3.2 %. It was found that the maximum isothermal strain in the Ti40,7Hf9,5Ni41,8Cu8 alloy was less than in the Ti40,7Hf9,5Ni44,8Cu5 alloy.

Microstructure and Tensile Properties of TRIP-Aided Steel Sheet Subjected to Hot-Rolling and Austempering

2021 ◽  
Vol 1016 ◽  
pp. 732-737
Author(s):  
Junya Kobayashi ◽  
Hiroto Sawayama ◽  
Naoya Kakefuda ◽  
Goroh Itoh ◽  
Shigeru Kuraoto ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Hot Rolling ◽  
Manufacturing Process ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Isothermal Holding ◽  
High Strength ◽  
Isothermal Transformation ◽  
Transformation Process ◽  
Steel Sheets

Various high strength steel sheets for weight reduction and safety improvement of vehicles have been developed. TRIP-aided steel with transformation induced plasticity of the retained austenite has high strength and ductility. Conventional TRIP-aided steels are subjected to austempering process after austenitizing. Generally, elongation and formability of TRIP-aided steel are improved by finely dispersed retained austenite in BCC phase matrix. The finely dispersed retained austenite and grain refinement of TRIP-aided steel can be achieved by hot rolling with heat treatment. Therefore, the improvement of mechanical properties of TRIP-aided steel is expected from the manufacturing process with hot rolling and then isothermal transformation process. In this study, thermomechanical heat treatment is performed by combining hot rolling and isothermal holding as the manufacturing process of TRIP-aided steel sheets. The complex phase matrix is obtained by hot rolling and then isothermal holding. Although the hardness of the hot rolled and isothermal held TRIP-aided steel is decreased, the volume fraction of retained austenite is increased.

Martensitic Transformation and Damping Behavior of Fe-Mn-Nb Damping Alloys

2021 ◽  
Vol 1016 ◽  
pp. 315-324
Author(s):  
Feng Chen ◽  
Fu Kuan Liang ◽  
Wei Lin Ye ◽  
Yun Xiang Tong ◽  
Li Li
Keyword(s):  
Martensitic Transformation ◽  
Volume Fraction ◽  
Damping Capacity ◽  
Damping Characteristics ◽  
Maximum Value ◽  
Damping Behavior ◽  
Ε Martensite ◽  
Tan Δ ◽  
Nb Addition

In the present study, the microstructure, martensitic transformation and damping characteristics of Fe-17Mn-xNb (x = 0, 0.5, 1, 2, 4 wt. %) alloys were investigated. Nb addition leads to the variation in both the volume fraction and the size of ε martensite, in addition, the formation of Fe2(Nb, Mn) precipitates. The martensitic transformation exhibits a tiny dependence on the content of Nb. The addition of Nb helps to enhance the damping capacity of Fe-17Mn. The maximum value of tan δ = 0.054 is achieved in Fe-17Mn-1Nb alloy, which is increased by 42% over Fe-17Mn. The damping mechanism caused by adding Nb is discussed in terms of the volume fraction and the size of ε martensite. Besides, the role of Fe2(Nb, Mn) is also taken into account.

Effect of Magnetic Field on Isothermal Martensitic Transformation in SUS304L Stainless Steel

2007 ◽  
Vol 561-565 ◽  
pp. 2333-2336 ◽  
Author(s):  
Jae Hwa Lee ◽  
Takashi Fukuda ◽  
Tomoyuki Kakeshita
Keyword(s):  
Magnetic Field ◽  
Stainless Steel ◽  
Martensitic Transformation ◽  
Isothermal Holding ◽  
Holding Time ◽  
Solution Treated ◽  
Α Phase ◽  
Fcc Phase ◽  
Isothermal Martensitic Transformation

We have found that solution-treated or sensitized SUS304L stainless steel transforms isothermally from the γ (fcc)-phase to the α' (bcc) martensite via the ε' (hcp) martensite, that is, the amount of the α'-phase increases with increasing holding time. By applying magnetic field, the α' martensite can be induced in the ε'-plate when the steel has a sufficiently large ε' plate formed beforehand by isothermal holding. However, the α' martensite cannot be induced by magnetic field in the ε'-plate formed beforehand by a deformation-induced transformation.

Strain variation during the isothermal martensitic transformation in Ti40.7Hf9.5Ni44.8Cu5 alloy

2019 ◽  
Vol 254 ◽  
pp. 266-268 ◽  
Author(s):  
Elena Demidova ◽  
Sergey Belyaev ◽  
Natalia Resnina ◽  
Alexander Shelyakov
Keyword(s):  
Martensitic Transformation ◽  
Strain Variation ◽  
Isothermal Martensitic Transformation

Transformation Textures in Unstable Austenitic Steel

2002 ◽  
Vol 125 (1) ◽  
pp. 12-17 ◽  
Author(s):  
R. Kubler ◽  
M. Berveiller ◽  
M. Cherkaoui ◽  
K. Inal
Keyword(s):  
Martensitic Transformation ◽  
Volume Fraction ◽  
Micromechanical Model ◽  
Slip Rate ◽  
Transformation Strain ◽  
Dislocation Motion ◽  
Lattice Spin ◽  
Two Phases ◽  
The One ◽  
Elastic Plastic Materials

During the martensitic transformation in elastic-plastic materials, the local transformation strain as well as the plastic flow inside austenite are strongly related with the crystallographic orientation of the austenitic lattice. Two mechanisms involved in these materials, i.e., plasticity by dislocation motion and martensitic phase formation are coupled through kinematical constraints so that the lattice spin of the austenitic grains is different from the one due to classical slip. In this work, the lattice spin ω˙eA of the austenitic grains is related with the slip rate on the slip systems of the two phases, γ˙A and γ˙M, the evolution of the martensite volume fraction f˙ and the overall rotation rate Ω˙ of the grains. This new relation is integrated in a micromechanical model developed for unstable austenite in order to predict the evolution of the austenite texture during TRansformation Induced Plasticity (TRIP). Results for the evolution of the lattice orientation during martensitic transformation are compared with experimental data obtained by X-ray diffraction on a 304 AISI steel.

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