Enhanced Thermal Stability of the Low‐carbon Ultrafine Grain Steel with Nano Precipitates

2021 ◽  
Author(s):  
Qingxiao Zhang ◽  
Qing Yuan ◽  
Zhoutou Wang ◽  
Wenwei Qiao ◽  
Guang Xu
Keyword(s):  
Thermal Stability ◽  
Ultrafine Grain ◽  
Low Carbon ◽  
Thermal Stability Of

Influence of plastic deformation on thermal stability of low carbon bainitic steel

2015 ◽  
Vol 22 (1) ◽  
pp. 60-66 ◽  
Author(s):  
Chao Sun ◽  
Shan-wu Yang ◽  
Rui Zhang ◽  
Xian Wang ◽  
Hui Guo
Keyword(s):  
Thermal Stability ◽  
Plastic Deformation ◽  
Bainitic Steel ◽  
Low Carbon ◽  
Thermal Stability Of

Grain Refinement of an Al-Cu-Mg Alloy by Microalloying and Common Thermo-Mechanical Treatment

2007 ◽  
Vol 546-549 ◽  
pp. 917-922
Author(s):  
Bao Lin Wu ◽  
Gui Ying Sha ◽  
Yi Nong Wang ◽  
Yu Dong Zhang ◽  
Claude Esling
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Mechanical Treatment ◽  
Grain Structure ◽  
Mg Alloy ◽  
Ultrafine Grain ◽  
Fine Grain ◽  
Thermo Mechanical Treatment ◽  
Ultrafine Grain Structure ◽  
Thermal Stability Of

Heavy deformation plus micro alloying could be an effective way to obtain ultrafine grain structure of metals. In the present work, an Al-Cu-Mg alloy was microalloyed with Zr to obtain homogeneous precipitates and then heavily deformed by conventional forging at high temperature. The possible refining processing routes were studied and the superplasticity behaviors of the alloy was investigated. Results show that the micro alloyed alloy can be stably refined to 3-5μm under conventional processing routes. The Al-3Zr precipitates act both as additional sites to enhance recrystallization nucleation rate and pins to impede grain growth to increase the thermal stability of the fine grain structure. However, as the Al3Zr precipitates remains along grain boundaries, the superplastic capability of the material is not high. At 430°C with 1×10-4S-1 strain rate, the elongation obtained was 260%.

Evolution of Microstructures in a Low Carbon Bainitic Steel during Reheating

2005 ◽  
Vol 475-479 ◽  
pp. 121-124 ◽  
Author(s):  
Hui Bin Wu ◽  
Shan Wu Yang ◽  
S.Q. Yuan ◽  
Cheng Jia Shang ◽  
Xue Min Wang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Bainitic Ferrite ◽  
Hardness Measurement ◽  
Granular Bainite ◽  
Low Carbon ◽  
Time Curve ◽  
History Of ◽  
Two Peaks ◽  
Thermal Stability Of ◽  
Synthetic Microstructures

Cooled in water after isothermal relaxation of deformed austenite for different time, a Nb-bearing microalloyed steel always exhibited synthetic microstructures of bainitic ferrite, granular bainite and acicular ferrite. When these samples were reheated to and held at 650°C or 700 °C, the non-equilibrious microstructures tended to evolve into equilibrious ones, accompanied by obvious change of hardness. The rate of microstructures evolution was closely related to relaxation time of deformed austenite. The sample relaxed for 60s displayed the highest thermal stability, while microstructure evolution was quickest in the sample relaxed for 1000s even though it was softest before reheating. By hardness measurement, it was found that softening was not only process occurring during reheating, in which hardness fluctuated with time. There were two peaks in hardness-time curve of each sample having undergone relaxation, while single peak occurred in the curve of the sample not being relaxed. These results indicate that thermal stability of microstructures is determined by their history of formation.

scholarly journals Thermal Stability of Retained Austenite and Properties of A Multi-Phase Low Alloy Steel

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 807 ◽  
Author(s):  
Zhenjia Xie ◽  
Lin Xiong ◽  
Gang Han ◽  
Xuelin Wang ◽  
Chengjia Shang
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Alloy Steel ◽  
Retained Austenite ◽  
Mechanical Stability ◽  
Volume Fraction ◽  
Low Carbon ◽  
Low Alloy Steel ◽  
Multi Phase ◽  
Thermal Stability Of

In this work, we elucidate the effects of tempering on the microstructure and properties in a low carbon low alloy steel, with particular emphasis on the thermal stability of retained austenite during high-temperature tempering at 500–700 °C for 1 h. Volume fraction of ~14% of retained austenite was obtained in the studied steel by two-step intercritical heat treatment. Results from transmission electron microscopy (TEM) and X-ray diffraction (XRD) indicated that retained austenite had high thermal stability when tempering at 500 and 600 °C for 1 h. The volume fraction was ~11–12%, the length and width remained ~0.77 and 0.21 μm, and concentration of Mn and Ni in retained austenite remained ~6.2–6.6 and ~1.6 wt %, respectively. However, when tempering at 700 °C for 1 h, the volume fraction of retained austenite was decreased largely to ~8%. The underlying reason could be attributed to the growth of austenite during high-temperature holding, leading to a depletion of alloy contents and a decrease in stability. Moreover, for samples tempered at 700 °C for 1 h, retained austenite rapidly transformed into martensite at a strain of 2–10%, and a dramatic increase in work hardening was observed. This indicated that the mechanical stability of retained austenite decreased.

Thermal stability of an ultrafine grain β-Ti alloy

2012 ◽  
Vol 556 ◽  
pp. 582-587 ◽  
Author(s):  
D. Kent ◽  
W.L. Xiao ◽  
G. Wang ◽  
Z. Yu ◽  
M.S. Dargusch
Keyword(s):  
Thermal Stability ◽  
Ultrafine Grain ◽  
Ti Alloy ◽  
Thermal Stability Of

Low Carbon Low Alloy Submicro-Steel with Nano-Precipitation

2006 ◽  
Vol 503-504 ◽  
pp. 511-514
Author(s):  
Bi Shi ◽  
Hong Wei Song ◽  
Jun Bao Zhang ◽  
Han-Qing Cao ◽  
Xiu Fang Wang
Keyword(s):  
Thermal Stability ◽  
Steel Sheet ◽  
Average Diameter ◽  
Warm Rolling ◽  
High Thermal Stability ◽  
Low Carbon ◽  
Dislocation Arrays ◽  
Different Temperatures ◽  
Refinement Mechanism ◽  
Thermal Stability Of

In the present work, low carbon low alloy submicro-steel sheet has been developed successfully by severe warm-rolling (SWR) at 500 °C through a single pass. The result shows submicro-structure can be fabricated by severe rolling. The formation of the submicro-structure is attributed to the grain refinement mechanism induced by the severe plastic deformation (SPD). The refinement involves the cutting and subdividing of the original micro-crystals into ultrafine grains by dense dislocation arrays. To a certain extent, dynamic recrystallization in ferrite during SWR also seems to contribute to the formation of the submicro-structure. The thermal stability of the submicro-steel was investigated by annealing the steel at different temperatures. The investigation indicated that the submicro-steel can be subjected to annealing at 550°C without apparent grain growth. The unusually high thermal stability can be attributed to the pining effect of numerous uniformly distributed nano-precipitates in the steel. The sizes of the nano-precipitates belong to two different orders. The average diameter of the large precipitates is about 30 nm and the smaller one less than 10 nm.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

Microstructure studies of tungsten silicide schottky contacts on Gaas

1987 ◽  
Vol 45 ◽  
pp. 328-329
Author(s):  
Yih-Cheng Shih ◽  
E. L. Wilkie
Keyword(s):  
Thermal Stability ◽  
Field Effect Transistors ◽  
Schottky Contact ◽  
Schottky Contacts ◽  
Excellent Thermal Stability ◽  
Barrier Heights ◽  
Gaas Substrates ◽  
Film Adhesion ◽  
Threshold Voltages ◽  
Thermal Stability Of

Tungsten silicides (WSix) have been successfully used as the gate materials in self-aligned GaAs metal-semiconductor-field- effect transistors (MESFET). Thermal stability of the WSix/GaAs Schottky contact is of major concern since the n+ implanted source/drain regions must be annealed at high temperatures (∼ 800°C). WSi0.6 was considered the best composition to achieve good device performance due to its low stress and excellent thermal stability of the WSix/GaAs interface. The film adhesion and the uniformity in barrier heights and ideality factors of the WSi0.6 films have been improved by depositing a thin layer of pure W as the first layer on GaAs prior to WSi0.6 deposition. Recently WSi0.1 has been used successfully as the gate material in 1x10 μm GaAs FET's on the GaAs substrates which were sputter-cleaned prior to deposition. These GaAs FET's exhibited uniform threshold voltages across a 51 mm wafer with good film adhesion after annealing at 800°C for 10 min.

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