Strain Gradient Hardening and Pressure Induced Phase Transformation of Metals by HPT

2008 ◽  
Vol 584-586 ◽  
pp. 493-500 ◽  
Author(s):  
Minoru Umemoto ◽  
Yoshikazu Todaka ◽  
Jun Sasaki ◽  
Innocent Shuro
Keyword(s):  
High Pressure ◽  
Phase Transformation ◽  
Strain Gradient ◽  
Volume Fraction ◽  
Radial Strain ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Ambient Conditions ◽  
Ω Phase ◽  
Α Phase

Two unique characteristics of HPT as a SPD process, namely deformation with strain gradient and deformation under high pressure, were investigated. The effect of strain gradient was examined using low carbon steel. HPTed samples showed hardening at the center of the specimen where shear strain is principally zero and saturation hardness was higher than those without strain gradient such as ECAP or ARB. HPT experiments using specimen with different radial strain gradient in one sample also showed strain gradient hardening. The effect of high pressure during HPT was examined using pure Ti which transformed from α phase to ω phase when HPTed at high pressure. The volume fraction of ω phase increases with strain and with decreasing oxygen content. The ω phase is metastable at ambient conditions and it transforms back to α phase during heating.

Effect of Mg Addition on the Characterization of γ-α Phase Transformation During Continuous Cooling in Low Carbon Steel

2015 ◽  
Vol 86 (12) ◽  
pp. 1530-1540 ◽  
Author(s):  
Xiaobing Li ◽  
Yi Min ◽  
Chengjun Liu ◽  
Maofa Jiang
Keyword(s):  
Phase Transformation ◽  
Carbon Steel ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Continuous Cooling ◽  
Α Phase ◽  
Mg Addition

The Prediction of the Flow Stress of an Extra-Low Carbon Steel in the Two-Phase Region Using Continuous Cooling Curves

1996 ◽  
Vol 118 (4) ◽  
pp. 463-470 ◽  
Author(s):  
Yhu-Jen Hwu ◽  
J. G. Lenard ◽  
J. J. M. Too
Keyword(s):  
Phase Transformation ◽  
Flow Stress ◽  
Carbon Steel ◽  
Volume Fraction ◽  
Low Carbon Steel ◽  
Phase Region ◽  
Cooling Curves ◽  
Low Carbon ◽  
Two Phase ◽  
Continuous Cooling

Continuous cooling curves of an extra-low carbon steel under three cooling rates are measured. The flow stress of the steel is established in compression tests during which the temperature is continuously decreasing. The phase transformation temperatures are determined from the cooling rate curve. The latent heat during phase transformation is calculated. A new variable, related to the volume fraction of transformation, is defined. Experimental results show that the relationship between the softening ratio of the flow stress due to phase transformation and this new variable may be described by a quadratic relationship. Based on this relationship and the continuous cooling curves, the flow stresses in the two-phase region are successfully predicted.

scholarly journals The Phase Transformations Induced by High-Pressure Torsion in Ti–Nb-Based Alloys

2021 ◽  
pp. 1-7
Author(s):  
Anna Korneva ◽  
Boris Straumal ◽  
Askar Kilmametov ◽  
Lidia Lityńska-Dobrzyńska ◽  
Robert Chulist ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transformation ◽  
Phase Transformations ◽  
High Pressure Torsion ◽  
Chemical Compositions ◽  
Β Phase ◽  
Ω Phase ◽  
Α Phase ◽  
Nb Content ◽  
Long Time

The study of the fundamentals of the α → ω and β → ω phase transformations induced by high-pressure torsion (HPT) in Ti–Nb-based alloys is presented in the current work. Prior to HPT, three alloys with 5, 10, and 20 wt% of Nb were annealed in the temperature range of 700–540°C in order to obtain the (α + β)-phase state with a different amount of the β-phase. The samples were annealed for a long time in order to reach equilibrium Nb content in the α-solid solution. Scanning electron microscope (SEM), transmission electron microscopy, and X-ray diffraction techniques were used for the characterization of the microstructure evolution and phase transformations. HPT results in a strong grain refinement of the microstructure, a partial transformation of the α-phase into the ω-phase, and a complete β → ω phase transformation. Two kinds of the ω-phase with different chemical compositions were observed after HPT. The first one was formed from the β-phase, enriched in Nb, and the second one from the almost Nb-pure α-phase. It was found that the α → ω phase transformation depends on the Nb content in the initial α-Ti phase. The less the amount of Nb in the α-phase, the more the amount of the α-phase is transformed into the ω-phase.

Magnetic Characterization of SUS316L Deformed by High Pressure Torsion

2011 ◽  
Vol 239-242 ◽  
pp. 1300-1303
Author(s):  
Hong Cai Wang ◽  
Minoru Umemoto ◽  
Innocent Shuro ◽  
Yoshikazu Todaka ◽  
Ho Hung Kuo
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Stainless Steel ◽  
Phase Transformation ◽  
Austenitic Stainless Steel ◽  
Volume Fraction ◽  
High Pressure Torsion ◽  
Austenitic Matrix ◽  
Magnetic Characterization

SUS316L austenitic stainless steel was subjected to severe plastic deformation (SPD) by the method of high pressure torsion (HPT). From a fully austenitic matrix (γ), HPT resulted in phase transformation from g®a¢. The largest volume fraction of 70% a¢ was obtained at 0.2 revolutions per minute (rpm) while was limited to 3% at 5rpm. Pre-straining of g by HPT at 5rpm decreases the volume fraction of a¢ obtained by HPT at 0.2rpm. By HPT at 5rpm, a¢®g reverse transformation was observed for a¢ produced by HPT at 0.2rpm.

scholarly journals Quantitative Description of External Force Induced Phase Transformation in Silicon–Manganese (Si–Mn) Transformation Induced Plasticity (TRIP) Steels

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3781
Author(s):  
Zhongping He ◽  
Huachu Liu ◽  
Zhenyu Zhu ◽  
Weisen Zheng ◽  
Yanlin He ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Carbon Steel ◽  
Trip Steel ◽  
Retained Austenite ◽  
Low Carbon Steel ◽  
High Strength ◽  
High Plasticity ◽  
Low Carbon ◽  
Transformation Induced Plasticity ◽  
Trip Steels

Transformation Induced Plasticity (TRIP) steels with silicon–manganese (Si–Mn) as the main element have attracted a lot of attention and great interest from steel companies due to their low price, high strength, and high plasticity. Retained austenite is of primary importance as the source of high strength and high plasticity in Si–Mn TRIP steels. In this work, the cold rolled sheets of Si–Mn low carbon steel were treated with TRIP and Dual Phase (DP) treatment respectively. Then, the microstructure and composition of the Si–Mn low carbon steel were observed and tested. The static tensile test of TRIP steel and DP steel was carried out by a CMT5305 electronic universal testing machine. The self-built true stress–strain curve model of TRIP steel was verified. The simulation results were in good agreement with the experimental results. In addition, the phase transformation energy of retained austenite and the work borne by austenite in the sample during static stretching were calculated. The work done by austenite was 14.5 J, which was negligible compared with the total work of 217.8 J. The phase transformation energy absorption of retained austenite in the sample was 9.12 J. The role of retained austenite in TRIP steel is the absorption of excess energy at the key place where the fracture will occur, thereby increasing the elongation, so that the ferrite and bainite in the TRIP steel can absorb energy for a longer time and withstand more energy.

The Structure, Microhardness and Wear Resistance of Coatings Obtained through Non-Vacuum Electron Beam Cladding of Chromium and Titanium Carbides on Low Carbon Steel

2018 ◽  
Vol 927 ◽  
pp. 13-19 ◽  
Author(s):  
Tatyana A. Krylova ◽  
Konstantin V. Ivanov ◽  
Vladimir E. Ovcharenko
Keyword(s):  
Wear Resistance ◽  
Electron Beam ◽  
Carbon Steel ◽  
Volume Fraction ◽  
Structural Characteristics ◽  
Low Carbon Steel ◽  
Structural Features ◽  
Low Carbon ◽  
Indentation Tests ◽  
Titanium Carbides

An interrelation between structural features, microhardness and wear resistance was studied in the coatings obtained by non-vacuum relativistic electron beam cladding of chromium and titanium carbides powder mixture on low carbon steel. Five coatings differing in the amount of the entered energy were investigated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), indentation tests and wear resistance measurements. It was found that the concentration of alloying elements both in solid solution and eutectic as well as the volume fraction of eutectic are the main structural characteristics which defines the microhardness of the coatings. The distribution of TiC phase plays a key role in the resistance to wear.

Orientation Relationships and Variant Selection during α- to γ- Phase Transformation in Low Carbon Steel

2002 ◽  
Vol 408-412 ◽  
pp. 1191-1196 ◽  
Author(s):  
C.M. Park ◽  
G. Brückner ◽  
Günter Gottstein
Keyword(s):  
Phase Transformation ◽  
Carbon Steel ◽  
Low Carbon Steel ◽  
Variant Selection ◽  
Low Carbon ◽  
Orientation Relationships

scholarly journals Coupled model of temperature and phase transformation of hot rolling low carbon steel during cooling process

2019 ◽  
Vol 1168 ◽  
pp. 052047
Author(s):  
Su-fen Wang ◽  
Zhi-jie Li ◽  
Zhang defeng ◽  
Zhou donghai
Keyword(s):  
Phase Transformation ◽  
Carbon Steel ◽  
Hot Rolling ◽  
Low Carbon Steel ◽  
Coupled Model ◽  
Low Carbon ◽  
Cooling Process

Metal-matrix composite fabricated with gas tungsten arc melt injection and precoated with NiCrBSi alloy to increase the volume fraction of WC particles

2017 ◽  
Vol 24 (2) ◽  
pp. 195-202 ◽  
Author(s):  
Aiguo Liu ◽  
Da Li ◽  
Fanling Meng ◽  
Huanhuan Sun
Keyword(s):  
Wear Resistance ◽  
Metal Matrix ◽  
Volume Fraction ◽  
Low Carbon Steel ◽  
High Volume ◽  
Wear Loss ◽  
Low Carbon ◽  
Gas Tungsten Arc ◽  
The Matrix ◽  
Gas Tungsten

AbstractThe volume fraction, dissolution, and segregation of WC particles in metal-matrix composites (MMCs) are critical to their wear resistance. Low carbon steel substrates were precoated with NiCrBSi coatings and processed with gas tungsten arc melt injection method to fabricate MMCs with high volume fraction of WC particles. The microstructures and wear resistance of the composites were investigated. The results showed that the volume fraction of WC particles increased with decreasing hopper height and was as high as 44% when hopper height was 100 mm. The dissolution of WC particles was minimal. The content of the alloying elements decreased from the top to the bottom of the matrix. More WC particles dissolved in the overlapping area, where Fe3W3C carbide blocks could be found. The wear loss of the MMCs after 40 min was 6.9 mg, which is 76 times less than that of the substrate after the 4 min test.

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