Effect of Initial Microstructure on Soft Annealing of a Low-Carbon Bainitic Steel

A low-carbon bainitic tool steel exhibiting high hardness after hot rolling typically has poor machinability. To soften this type of steel and to accelerate the soft annealing process, an austenitizing step was designed based on thermodynamic calculations of phase stability and introduced prior to the annealing step. Different initial microstructures were prepared by three austenitizing temperatures (680 °C, 850 °C, 1000 °C) and three cooling methods (water quenching, oil quenching, and air cooling). The effect of initial microstructure on microstructures and hardness was studied. Softening equations, a function of annealing temperature and time, were established for different initial microstructures, and the relationships between annealing temperature, annealing time, activation energy, and hardness were explored. The predicted hardness was consistent with the measured values. Martensitic structure has a low activation energy for diffusion and a higher softening rate compared to that of the bainitic structure. In addition, the higher the carbide content in the bainitic structure, the smaller the activation energy tended to be.

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Effect of Different Annealing Process for Microstructure and Properties of 1200MPa HSLA Steel

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.713-715.2653 ◽

2015 ◽

Vol 713-715 ◽

pp. 2653-2657

Author(s):

Yu Pei ◽

Zhe Gao ◽

Yi Liu ◽

Shi Qian Zhao ◽

Chang Yu Xu ◽

...

Keyword(s):

Tensile Strength ◽

Room Temperature ◽

Annealing Temperature ◽

Hsla Steel ◽

High Strength ◽

Annealing Process ◽

Air Cooling ◽

Low Carbon ◽

Slow Cooling ◽

Microstructure And Properties

For C-Si-Mn low carbon HSLA(High Strength Low Alloyed) steel, the influence of microstructure and properties were researched on the different annealing processes. The result showed that the microstructure at room temperature of the steel were polygonal ferrite, island martensite and punctate bainite. With the increase of the annealing temperature, the content of martensite and bainiteincreased and the content of ferrite decreased. Accordingly, tensile strengthincreased from 1069MPa to 1498MPa, and the elongation decreased from 13.8% to 5.1%. With the increase of the overaging temperature, tensile strength decreased from 1315MPa to 1152MPa, and the elongationincreased from8.5% to9.8%. Finally, the optimum annealing process obtained that the annealing temperature was 820°C for 80s, slow cooling to 680°C, water quenching to room temperature, the overaging temperature was 280°C for 300s and air cooling to room temperature. The material obtained higher tensile strength and better elongation.

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Effect of Annealing Temperature on Deformed Microstructure of Low Carbon Martensite

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.213.143 ◽

2011 ◽

Vol 213 ◽

pp. 143-146

Author(s):

Jun Zhao ◽

Yong Ming Yang ◽

Jiu Chuan Chen ◽

Quan Xing Wen ◽

Li Tao Zhang ◽

...

Keyword(s):

Activation Energy ◽

Grain Size ◽

Annealing Temperature ◽

Steel Plate ◽

Low Carbon ◽

Average Grain Size ◽

Long Time ◽

New Type ◽

Lath Structure ◽

Carbon Martensite

In this paper, a new type steel plate with nano-layered martensite lath structure was produced by heavy cold-rolling. After rolling, subsequent annealing has great effect on the deformed martensite morphology and grain refinement. Microstructure recrystallizing course have occurred after long time annealing at 350°C. The recrystallization activation energy is 151 kJmol-1. The ultrafine ferrite grains (average grain size about 317nm), nano-carbides precipitated uniformly were seen in the specimen annealed at 500 °C. Annealing at and above 600 °C resulted in coarse ferrite grains with spheroidized coarse carbides, causing grain growth.

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Defect reduction in oxygen implanted silicon-on-insulator material during high-temperature annealing

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154998 ◽

1989 ◽

Vol 47 ◽

pp. 604-605

Author(s):

P. Roitman ◽

B. Cordts ◽

S. Visitserngtrakul ◽

S.J. Krause

Keyword(s):

High Temperature ◽

Annealing Temperature ◽

Silicon On Insulator ◽

High Dose ◽

High Temperature Annealing ◽

High Current ◽

Defect Reduction ◽

Annealing Step ◽

Multiple Cycle ◽

Defect Densities

Synthesis of a thin, buried dielectric layer to form a silicon-on-insulator (SOI) material by high dose oxygen implantation (SIMOX – Separation by IMplanted Oxygen) is becoming an important technology due to the advent of high current (200 mA) oxygen implanters. Recently, reductions in defect densities from 109 cm−2 down to 107 cm−2 or less have been reported. They were achieved with a final high temperature annealing step (1300°C – 1400°C) in conjunction with: a) high temperature implantation or; b) channeling implantation or; c) multiple cycle implantation. However, the processes and conditions for reduction and elimination of precipitates and defects during high temperature annealing are not well understood. In this work we have studied the effect of annealing temperature on defect and precipitate reduction for SIMOX samples which were processed first with high temperature, high current implantation followed by high temperature annealing.

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Development of NbTiB Microalloyed HSLA Steels for High-Strength Heavy Plate

Materials Science Forum ◽

10.4028/www.scientific.net/msf.500-501.565 ◽

2005 ◽

Vol 500-501 ◽

pp. 565-572 ◽

Cited By ~ 3

Author(s):

H. Meuser ◽

F. Grimpe ◽

S. Meimeth ◽

C.J. Heckmann ◽

C. Träger

Keyword(s):

High Strength ◽

Optimum Process ◽

Low Carbon ◽

Low Alloy Steel ◽

Alloying Element ◽

Heavy Plate ◽

Hsla Steels ◽

Bainitic Microstructure ◽

Bainitic Structure ◽

Low Temperature Toughness

This paper deals with the development of low carbon NbTiB micro-alloyed high strength low alloy steel for heavy plates with high wall thickness. In the production of heavy plate it is remarkably difficult to achieve a combination of high strength and good low-temperature toughness. Bainitic microstructures have shown the capability to attain such requirements. To achieve a bainitic microstructure even for heavy wall products the formation of bainite can be promoted and supported by the use of small amounts of boron as a micro-alloying element. This industrial research project is based on the addition of small amounts of boron to promote the desired bainitic structure. Mill rolling trials were carried out to determine the optimum process parameters. The results of experimental mill rolling trials on 35 mm plates will be presented in this paper.

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Laser Assisted High Entropy Alloy Coating on Low Carbon Steel

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.813.159 ◽

2019 ◽

Vol 813 ◽

pp. 159-164

Author(s):

Carlos Alberto Souto ◽

Gustavo Faria Melo da Silva ◽

Laura Angelica Ardila Rodriguez ◽

Aline C. de Oliveira ◽

Kátia Regina Cardoso

Keyword(s):

Wear Resistance ◽

Carbon Steel ◽

Low Carbon Steel ◽

High Hardness ◽

Alloy Coating ◽

High Entropy Alloy ◽

Nominal Composition ◽

Low Carbon ◽

High Entropy ◽

Scan Speed

Coatings with high entropy alloys of the AlCoCrFeNiV system were obtained by selective laser melting on low carbon steel substrates. The effect of the variation of the Fe and V contents as well as the laser processing parameters in the development of the coating were evaluated. The coatings were obtained from the simple powder mixtures of the high purity elemental components in a planetary ball mill. The coatings were obtained by using CO2 laser with a power of 100 W, diameter of 0.16 mm, and scan speed varying from 3 to 12 mm/s. Phase constituents, microstructure and hardness were investigated by XRD, SEM, and microhardness tester, respectively. Wear resistance measurements were carried out by the micro-abrasion method using ball-cratering tests. The coatings presented good adhesion to the substrate and high hardness, of the order of 480 to 650 HV. Most homogeneous coating with nominal composition was obtained by using the higher scan speed, 12 mm/s. Vanadium addition increased hardness and gave rise to a high entropy alloy coating composed by BCC solid solutions. Ball cratering tests conducted on HEA layer showing improvement of material wear resistance, when compared to base substrate, decreasing up to 88% its wear rate, from 1.91x10-6 mm3/Nmm to 0.23x10-6 mm3/Nmm.

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About the Electrical Activation of 1×1020 cm-3 Ion Implanted Al in 4H-SiC at Annealing Temperatures in the Range 1500 - 1950°C

Materials Science Forum ◽

10.4028/www.scientific.net/msf.924.333 ◽

2018 ◽

Vol 924 ◽

pp. 333-338 ◽

Cited By ~ 11

Author(s):

Roberta Nipoti ◽

Alberto Carnera ◽

Giovanni Alfieri ◽

Lukas Kranz

Keyword(s):

Activation Energy ◽

Sheet Resistance ◽

Annealing Time ◽

Thermal Activation ◽

Room Temperature ◽

Annealing Temperature ◽

Thermal Activation Energy ◽

Electrical Activation ◽

Temperature Range ◽

Annealing Temperatures

The electrical activation of 1×1020cm-3implanted Al in 4H-SiC has been studied in the temperature range 1500 - 1950 °C by the analysis of the sheet resistance of the Al implanted layers, as measured at room temperature. The minimum annealing time for reaching stationary electrical at fixed annealing temperature has been found. The samples with stationary electrical activation have been used to estimate the thermal activation energy for the electrical activation of the implanted Al.

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Increasing Hardness of Surface Layer of Low-Carbon Steel by Account of Plasma Treatment of Coating Modification

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.316.794 ◽

2021 ◽

Vol 316 ◽

pp. 794-802

Author(s):

Andrey E. Balanovsky ◽

Van Trieu Nguyen

Keyword(s):

Surface Layer ◽

Thermal Treatment ◽

Plasma Treatment ◽

Plasma Heating ◽

High Surface ◽

Surface Hardness ◽

High Hardness ◽

Diffusion Region ◽

Low Carbon ◽

Wide Range

The Purpose of paper is to conduct studies to assess the possibility of increasing the hardness of the surface layer of steel St3 grade by plasma heating of the applied surface coating containing powder alloy PR-N80X13S2R. Mixtures of pasta were divided into 2 groups: for furnace chemical-thermal treatment and plasma surface melting. The study of the microstructure showed a difference in the depth of the saturated layer, depending on the processing method, during chemical-thermal treatment-1 mm, plasma fusion - 2 mm. The results of measuring the surface micro-hardness showed that, the obtained coating from a mixture of PR-N80X13S2R + Cr2O3 + NH4Cl has a uniform high surface hardness (31-64 HRC), from a mixture of only PR-N80X13S2R - the surface hardness varies in a wide range (15-60 HRC). The study of the microhardness of the cross section of the surface layer showed that, the diffusion region: from a mixture of powder PR-N80X13S2R + Cr2O3 + NH4Cl has uniform hardness (450-490 HV); from a mixture of PR-N80X13S2R - hardness increases in the depth of the molten region (from 300 to 600 HV), and sharply decreases in the heat affected zone (210-170 HV). The use of PR-N80X13S2R alloy powder as the main component in the composition of the paste deposited on the St3 surface during plasma treatment leads to the formation of a doped surface layer with high hardness.

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Study of Detector-Grade CdMnTe:In Crystals Obtained by a Multi-Step Post-Growth Annealing Method

Crystals ◽

10.3390/cryst8100387 ◽

2018 ◽

Vol 8 (10) ◽

pp. 387 ◽

Cited By ~ 2

Author(s):

Pengfei Yu ◽

Yongren Chen ◽

Wei Li ◽

Wenfei Liu ◽

Bin Liu ◽

...

Keyword(s):

Annealing Temperature ◽

Crystal Quality ◽

High Resistivity ◽

Detector Performance ◽

Rocking Curve ◽

X Ray ◽

Annealing Step ◽

Subsequent Step ◽

Te Inclusions ◽

Annealing Method

A multi-step annealing method was successfully applied to inclusions reduction and resistivity improvement of CdMnTe:In (CMT:In) single crystals with high resistivity, including a Cd atmosphere annealing step followed by a Te atmosphere annealing step. After the Cd atmosphere annealing step, the density of Te inclusions was reduced distinctly, and it could be also decreased in the subsequent step of re-annealing under Te atmosphere. Both the resistivity and IR transmittance decreased notably after Cd atmosphere annealing, whereas they increased tremendously after re-annealing under a Te atmosphere. The reduction of full-width at-half-maximum (FWHM) and the increase of the intensity of the X-ray rocking curve indicated an improvement of the crystal quality. Meanwhile, after Cd atmosphere annealing, the increase of the intensity of the (D0,X) peak and the disappearance of the (A0,X) peak in photoluminescence (PL) measurements suggested further that the crystal quality was improved. The detector performance was enhanced obviously after annealing. The higher the annealing temperature, the better the performance was. The detector fabricated by CMT:In slice (Cd atmosphere annealing at 1073 K for 240 h and Te atmosphere re-annealing at 773 K for 120 h) with 9.43% energy resolution and 1.25 × 10−3 cm2/V μτ value had the best detector performance.

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Metamorphism of Air Bubbles in a Snow Crystal

Journal of Glaciology ◽

10.3189/s0022143000019778 ◽

1967 ◽

Vol 6 (46) ◽

pp. 561-564

Author(s):

Norikazu Maeno ◽

Daisuke Kuroiwa

Keyword(s):

Activation Energy ◽

Diffusion Processes ◽

Atomic Diffusion ◽

Mechanical Relaxation ◽

Air Bubbles ◽

A Value ◽

Snow Crystal ◽

Activation Energy For Diffusion ◽

Snow Crystals ◽

Natural Snow

RésuméObservations have been made of the modification produced by a temperature gradient in the shape of air bubbles in natural snow crystals, and also of the shrinkage of the bubbles with time. The rate of shrinkage is governed by a constant which is strongly temperature dependent with an activation energy of about 15.1 kcal./mole, a value sufficiently similar to the activation energy for diffusion of tritium, dielectric relaxation and mechanical relaxation to suggest that atomic diffusion processes may be responsible for all of these phenomena.

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