Effects of Peening Direction on Reverse Transformation Induced by Shot-Peening for Fe-33%Ni Alloy

2021 ◽  
Vol 1016 ◽  
pp. 1252-1257
Author(s):  
Hisashi Sato ◽  
Takuto Tominaga ◽  
Tadachika Chiba ◽  
Tomokazu Moritani ◽  
Yoshimi Watanabe
Keyword(s):  
Phase Transformation ◽  
Compressive Stress ◽  
Shot Peening ◽  
Transformation Temperature ◽  
Volume Fraction ◽  
Residual Compressive Stress ◽  
Reverse Transformation ◽  
Phase Transformation Temperature ◽  
Transformation Behavior ◽  
Ni Alloy

Effects of peening direction on the reverse transformation induced by the shot-peening for the Fe-33 mass%Ni alloy with large amount of martensite (α’) are investigated. When the angle between the peened surface and the peening direction (Hereafter, peening angle) is 90 o, the reverse transformation occurs and subsequently martensitic transformation is induced by the shot-peening. On the other hand, in case of the peening angle of 30 o, only reverse transformation occurs. Furthermore, the volume fraction of austenite (γ) in the specimen after the shot-peening increases as the peening angle decreases. This means that the reverse transformation induced by the shot-peening is enhanced by decreasing the peening angle. Moreover, residual compressive stress around the peened surface increases as the peening angle decreases. Since the hydrostatic compressive stress decreases phase transformation temperature, the phase transformation temperature around the peened surface would be decreased by the shot-peening. Therefore, the reverse transformation behavior depending on the peening angle can be explained by the residual compressive stress due to the shot-peening.

A Computational Model for Phase Transformation-Temperature-Distortion Coupling of AISI 5120 Steel

2006 ◽  
Vol 118 ◽  
pp. 387-392 ◽  
Author(s):  
Seok Jae Lee ◽  
Young Kook Lee
Keyword(s):  
Heat Transfer ◽  
Phase Transformation ◽  
Kinetic Models ◽  
Transformation Temperature ◽  
Volume Fraction ◽  
Coupled Model ◽  
Avrami Equation ◽  
Transformation Kinetic ◽  
Phase Transformation Temperature ◽  
Finite Element Software

A coupled model for predicting phase transformation, temperature, and distortion of AISI 5120 steel occurring during heat treatment process has been developed. The phase transformation kinetic models were made using Johnson-Mehl-Avrami equation and the additivity rule based on theoretical thermodynamic model and experimental dilatometric data. Especially, the transformation strains measured during cooling were converted to the volume fraction of each phase for the kinetic models using a relation between transformation strain and atomic volume change. The heat transfer coefficients in quench media were calculated by inverse method of the heat transfer equation to the measured surface temperature history. To predict the temperature and distortion accurately, the thermal and mechanical data were used as a function of temperature and each phase based on the experimental data. The coupled model for phase transformation, temperature, and distortion has been implemented in the commercial finite element software ABAQUS as user subroutines. The calculated results by the coupled model were compared with the experimental ones.

Reverse Transformation Behavior Induced by Shot-Peening for SUS410S Martensitic Stainless Steel

2016 ◽  
Vol 879 ◽  
pp. 2003-2007
Author(s):  
Nagomi Tsuboi ◽  
Serika Higa ◽  
Hisashi Sato ◽  
Yoshimi Watanabe
Keyword(s):  
Stainless Steel ◽  
Shear Strain ◽  
Shot Peening ◽  
Martensitic Stainless Steel ◽  
Volume Fraction ◽  
Martensite Phase ◽  
Reverse Transformation ◽  
Transformation Behavior ◽  
Thermally Induced ◽  
Large Shear Strain

Reverse transformation behavior of thermally-induced martensite phase (α’) in martensitic stainless steel by the shot-peening is investigated. It is found that volume fraction of austenite phase (γ) on the peened surface is increased by the shot-peening under elevated temperature. This means that reverse transformation from thermally-induced α’ to γ can be induced by the shot-peening. Moreover, with decreasing the distance between blast nozzle and specimen (blast distance), the reverse transformation occurs more remarkably. This is because that larger shear strain can be induced by the shot-peening with shorter blast distance. Furthermore, thickness of the deformation-induced layer becomes larger as the blast distance decreases. It can be concluded that the reverse transformation in SUS410S with thermally-induced α’ occurs by large shear strain during the shot-peening.

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.

scholarly journals Influence of Heat Treatment on the Workability of Modified 9Cr-2W Steel with Higher B Content

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 904
Author(s):  
Hyeong Min Heo ◽  
Jun Hwan Kim ◽  
Sung Ho Kim ◽  
Jong Ryoul Kim ◽  
Won Jin Moon
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Phase Transformation ◽  
Transformation Temperature ◽  
Fracture Behavior ◽  
Rolling Process ◽  
Normal Direction ◽  
Phase Transformation Temperature ◽  
Treatment Conditions ◽  
Creep Characteristics

In this study, the effect of heat treatment on the fracture behavior of alloy B steel with boron (B) contents as high as 130 ppm was investigated. The Alloy B are derived from Gr.92 steel with outstanding creep characteristics. The amounts of minor alloying elements such as B, N, Nb, Ta, and C were optimized to achieve better mechanical properties at high temperatures. Hence, workability of the alloy B and Gr.92 were compared. An increase in the B content affected the phase transformation temperature and texture of the steel. The development of the {111}<uvw> components in γ-fibers depended on the austenite fraction of the steel after the phase transformation. An increase in the B content of the steel increased its α-to-γ phase transformation temperature, thus preventing the occurrence of sufficient transformation under the normalizing condition. Cracks occurred at the point of the elastic-to-plastic deformation transition in the normal direction during the rolling process, thereby resulting in failure. Therefore, it is necessary to avoid intermediate heat treatment conditions, in which γ-fibers do not fully develop, i.e., to avoid an imperfect normalization.

An Approach for Modeling Transformation Plasticity Using a Phase Field Model

2011 ◽  
Vol 320 ◽  
pp. 285-290 ◽  
Author(s):  
Takuya Uehara
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Phase Field ◽  
Transformation Temperature ◽  
Field Model ◽  
Volume Fraction ◽  
Phase Field Model ◽  
Field Variable ◽  
Transformation Plasticity ◽  
Temperature Strain

In this paper, an approach for modeling transformation plasticity using a phase field model is presented. A conventional formula is utilized to represent the strain due to transformation plasticity as well as thermal expansion and transformation dilatation. A phase-field variable is introduced to express the state of phase in material instead of volume fraction, and numerical simulations under simplified conditions are demonstrated. As a result, the strain induced by phase transformation is suitably regenerated, and qualitatively appropriate temperature-strain curves are obtained. In addition, the effect of each parameter is investigated, and various dependencies, such as transformation temperature and stress, on the induced strain are demonstrated. It is then concluded that the results indicate the applicability of the presented model for practical use by adjusting the parameters.

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