Effect of Heat Treatment on the Precipitation Behavior and Hardness of the Second Phase of 0Cr21Mn17Mo3N0.8 High Nitrogen Alloys

2019 ◽  
Vol 944 ◽  
pp. 373-377
Author(s):  
You Yang ◽  
Yun Xiu Xu ◽  
Zi Wei Chen ◽  
Yan Huang
Keyword(s):  
Heat Treatment ◽  
Precipitation Process ◽  
Second Phase ◽  
High Nitrogen ◽  
Slow Cooling ◽  
Treatment Processes ◽  
Transmission Electron ◽  
Layer Deposition ◽  
Nitrogen Alloy ◽  
Heat Preservation

The effects of different heat treatment processes on the morphology, quantity and size of the precipitated nitrides phase of 0Cr21Mn17Mo3N0.8 high nitrogen alloy were studied. The microstructure of the alloy was observed and characterized by metallographic microscope, transmission electron microscope, etc. And the hardness of high nitrogen alloy under different treatment processes were tested. The results showed that sample alloy was cooling in the furnace after heat preservation of 1140°C for 8h. Lamellar nitride is precipitated from the alloy, its composition is Cr2N, its size is about 50-100nm, and the precipitation process mainly occurs 1-2mm below the surface layer. This can make the alloys to form surface-reinforced composites. Meanwhile, the hardness of the alloy has increased significantly from 29.3HRC to 61.3HRC, because of the precipitation of the second phase. The high nitrogen alloys after slow cooling treatment were treated with spheroidization at the temperature lower than that of the complete austenitizing, and the layered deposition began fusing at 950°C. Under the temperature of 1120°C heat preservation for 8h, then water quenching, slice layer deposition completely dissolved into granule, and the particle size is about 20nm to 50nm, the alloy of hardness after spheroidizing has decreased to 48.3HRC.

The effect of grain size on microstructure and stress relaxation in polycrystalline Y1Ba2Cu3O7−δ

1989 ◽  
Vol 4 (2) ◽  
pp. 248-256 ◽  
Author(s):  
T. M. Shaw ◽  
S. L. Shinde ◽  
D. Dimos ◽  
R. F. Cook ◽  
P. R. Duncombe ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Stress Relaxation ◽  
Optical Microscopy ◽  
Slow Cooling ◽  
Hierarchical Arrangement ◽  
Transmission Electron ◽  
Processing Variables

We have used transmission electron microscopy and optical microscopy to examine the effect that grain size and heat treatment have on twinning and microcracking in polycrystalline Y1Ba2Cu3O7−δ. It is shown that isothermal oxygenation heat treatments produce twin structures consisting of parallel twins, with a characteristic spacing that increases with increasing grain size. Slow cooling through the temperature range where the orthorhombic-to-tetragonal transformation induces twinning, however, produces a structure consisting of a hierarchical arrangement of intersecting twins, the scale of which appears to be independent of grain size. It is also shown that the microcracking induced by anisotropic changes in grain dimensions on cooling or during oxygenation can be suppressed if the grain size of the material is kept below about 1 μm. The results are examined in the light of current models for transformation twinning and microcracking and the models used to access the effect other processing variables such as oxygen content, doping or heat treatment may have on the microstructure of Y1Ba2Cu3O7−δ.

Effect of the Shapes of Diversion Umbrellas on Temperature Field in a Large Spherical Tank During Heat Treatment Processes

2015 ◽  
Author(s):  
Fang Ji ◽  
Xiaomei Wang ◽  
Guide Deng ◽  
Jingliang Feng ◽  
Haifeng Liang
Keyword(s):  
Heat Treatment ◽  
Internal Flow ◽  
Combustion Method ◽  
Post Weld Heat Treatment ◽  
Treatment Processes ◽  
Spherical Tank ◽  
Simulation Based ◽  
Fluent Software ◽  
Heat Preservation ◽  
Large Spherical

Internal combustion method is widely used to reduce residual stress of large spherical tanks in China, when post weld heat treatment of the spherical tanks is required. During the heat treatment processes diversion umbrellas set in the spherical tanks can be utilized to drop the maximal difference of wall temperatures of the spherical tanks. Numerical simulation based on Fluent software was carried out to study the effect of an A-shaped diversion umbrella and three V-shaped diversion umbrellas with different angles on internal flow and wall temperatures of a 10000 m3 spherical tank. The results show that the V-shaped diversion umbrellas have better performance than the A-shaped one, but the angles of the V-shaped diversion umbrellas from 100° to 140° have little effect on maximum wall temperature differences of the spherical tank during the heat preservation stage of the heat treatment processes.

scholarly journals Effect of Niobium and Titanium Addition on Formation of Second Phase Particles in CHQ Steel Using Transmission Electron Microscope

2021 ◽  
Vol 40 (1) ◽  
pp. 31-37
Author(s):  
Shahid Hussain Abro
Keyword(s):  
Heat Treatment ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Weight Percent ◽  
Holding Time ◽  
Second Phase ◽  
Steel Matrix ◽  
Ehlers Danlos Syndrome ◽  
Transmission Electron ◽  
Second Phase Particles

It is common practice that formation of second phase particles such as nitrides or carbides in the steel matrix has significant role to control the grain size of steel. An attempt is made in the present research work to find out the role of nitrogen to form the nitride particles either with Al, Ti, B, Cr or Si. Two steel samples Steel-A and Steel-B with same titanium and aluminum weight percent in the chemical composition were obtained in hot rolled conditions from international market with only the difference of presence of Niobium in Steel-A. Solution heat treatment was performed at 1350°C with 60 minutes holding time in protherm heat treatment furnace available locally was used to dissolve the particles and then steel samples were reheat treated at 800°C with holding time of 60 minutes and water quenched and microstructure was revealed. Transmission electron microscope connected with Ehlers-Danlos Syndrome (EDS) was used to reveal the morphology of second phase particles. Both samples for a high resolution power Transmission Electron Microscopy (TEM) (Jeol JEM 3010) analysis were prepared by using carbon extraction replica method in 5% Nital solution as an etching technique. Both samples were then caught in copper grid of 3mm for using TEM analysis. TEM micrographs clearly revealed the second phase particles in the matrix of steel. The EDS peaks were studied and it was found that the peaks showed the titanium peaks in both the samples A and B and surprisingly there was no any peak found for aluminum. Stoichiometric calculations were carried out and it was found that weight percent nitrogen required for forming TiN is 0.0073, however the total nitrogen present in both the steels A and B is 0.0058 and 0.0061 respectively. That means that all the nitrogen present in the steel matrix was consumed by titanium to form the Titanium Nitride (TiN) so there was no nitrogen remain to fulfil the requirement of aluminum to form the Aluminum Nitride (AlN) particles.

scholarly journals Study of the precipitation hardening process in recycled Al-Si-Cu cast alloys

2017 ◽  
Vol 62 (1) ◽  
pp. 397-403 ◽  
Author(s):  
L. Kuchariková ◽  
E. Tillová ◽  
M. Matvija ◽  
J. Belan ◽  
M. Chalupová
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Precipitation Hardening ◽  
Cast Alloy ◽  
Solution Treatment ◽  
Second Phase ◽  
Thin Foils ◽  
Transmission Electron ◽  
Different Temperatures ◽  
Cast Alloys

AbstractThe formation of extremely small uniformly dispersed particles of a second phase within the original phase matrix during heat treatment changed material properties. Therefore the characterization of precipitation had been investigated using high resolution transmission electron microscopy (TEM) and electron diffraction of thin foils for an AlSi9Cu3 cast alloy. For investigation the hardening effect onto mechanical properties of aluminium cast was used heat treatment, which consisted from solution treatment at 515°C / 4 hours (h), followed by quenching into water with temperature 50°C and artificial aging using different temperatures 170°C and 190°C with different holding time 2, 4, 8, 16, and 32 hours. The observations of microstructure and substructure reveals that precipitation hardening has caused great changes in size, morphology and distributions of structural components, the formation of precipitates of Cu phases, and the change of mechanical properties as well.

Measurement of compositional changes accompanying solid-state transformations at grain boundaries in metals

1987 ◽  
Vol 45 ◽  
pp. 296-299
Author(s):  
Ernest L. Hall ◽  
Clyde L. Briant
Keyword(s):  
Solid State ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Precipitation Process ◽  
Second Phase ◽  
Slow Cooling ◽  
Collector Plate ◽  
Compositional Changes ◽  
Property Changes ◽  
Boundary Chemistry

In many multicomponent metallic systems, solid-state precipitation processes can occur upon slow cooling or isothermal aging of solutionized material. Frequently, the precipitates form at grain boundaries, which are preferred sites for the nucleation and growth of the second phase. The precipitates generally grow through a combination of matrix and grain boundary diffusion, in which the grain boundary acts as a collector plate for the delivery of the solute to the growing precipitate. The precipitation process is thus accompanied by significant changes in the chemistry of the grain boundary and matrix regions near the grain boundary. These grain boundary chemistry changes can have a profound effect on the macroscopic properties of the material, including corrosion resistance, strength, and ductility. In order to understand the mechanism associated with these property changes, it is necessary to obtain a complete and precise description of the magnitude and extent of the compositional changes which have occurred at the grain boundaries.

Effect of Low Cu Addition and Thermo-Mechanical History on Precipitation in Al-Mg-Si Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 1014-1019 ◽  
Author(s):  
Takeshi Saito ◽  
Calin D. Marioara ◽  
Jostein Røyset ◽  
Randi Holmestad
Keyword(s):  
Heat Treatment ◽  
Cooling Rate ◽  
Solution Heat Treatment ◽  
Precipitation Hardening ◽  
Peak Hardness ◽  
Isothermal Heat Treatment ◽  
Slow Cooling ◽  
Transmission Electron ◽  
Material Hardness ◽  
Initial Hardness

The effect of cooling rate after solution heat treatment and its combination with 1% pre-deformation on precipitation hardening in two Al-Mg-Si alloys is investigated by transmission electron microscopy (TEM), and related to material hardness. Two alloys have been used, one Cu-free and the other with low Cu additions (~0.1 wt%), both having the same amounts of other solutes. A double peak hardness evolution during an isothermal heat treatment was observed with slow cooling after solution heat treatment. This effect was less pronounced in the Cu-added alloy. The 1% pre-deformation also made this effect less pronounced, but it led to faster initial hardness evolution and delayed over-aging. Maximum hardness was not influenced by cooling rate and the pre-deformation. Hardness was directly related to precipitate number densities.

Influence of Low Cu Addition on Quench Sensitivity in Al-Mg-Si Alloys

2014 ◽  
Vol 922 ◽  
pp. 616-621
Author(s):  
Takeshi Saito ◽  
Calin D. Marioara ◽  
Jostein Røyset ◽  
Randi Holmestad
Keyword(s):  
Heat Treatment ◽  
Solution Heat Treatment ◽  
The Other ◽  
Isothermal Heat Treatment ◽  
Maximum Hardness ◽  
Slow Cooling ◽  
Quench Sensitivity ◽  
Cooling Conditions ◽  
Transmission Electron ◽  
Material Hardness

Quench sensitivity in two Al-Mg-Si alloys, one Cu-free and the other with low Cu additions (~0.1 wt%), both having the same amounts of other solutes, has been investigated using transmission electron microscopy (TEM) and corresponding material hardness. A two stage hardness evolution during an isothermal heat treatment was observed with slow cooling after solution heat treatment. This effect was less pronounced in the Cu-added alloy. However maximum hardness was not influenced by cooling rate, which could be related to higher precipitate number densities and volume fractions. Both alloys were over-aged faster in the slow cooling conditions.

scholarly journals A Study on High Strength, High Plasticity, Non-Heat Treated Die-Cast Aluminum Alloy

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 295
Author(s):  
Ruizhang Hu ◽  
Chun Guo ◽  
Mingliang Ma
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Aluminum Alloy ◽  
Heat Treating ◽  
Second Phase ◽  
Cast Aluminum Alloy ◽  
Cast Aluminum ◽  
Transmission Electron ◽  
Heat Treated ◽  
Die Cast

The non-heat-treated, die-cast aluminum alloy samples were prepared meticulously via die-casting technology. The crystal structure, microstructure, and phase composition of the samples were comprehensively studied through electron backscatter diffraction (EBSD), metallographic microscopy, spectrometer, and transmission electron microscopy (TEM). The microhardness and tensile properties of the samples were tested. The die-cast samples were found to have desirable properties by studying the structure and performance of the samples. There were no defects, such as pores, cold partitions, or surface cracks, found. The metallographic structure of the samples was mainly α-Al, and various phases were distributed at the grain boundaries. Before heat treating, α-Al grains were mainly equiaxed with a great number of second phase particles at the grain boundaries. After heat treating, the α-Al grains were massive and coarsened, and the second phase grains were refined and uniformly distributed, compared with those before the heat treating. The EBSD results showed that the grain boundary Si particles were solid solution decomposed after heat treatment. The particles became smaller, and their distribution was more uniform. Transmission electron microscopy found that there were nano-scale Al-Mn, Al-Cu, and Cu phases dispersed in the samples. The average microhardness of the samples before heat treating was 114 HV0.1, while, after the heat treating, the microhardness reached 121 HV0.1. The mechanical features of the samples were tremendous, and the obtained die-cast aluminum alloy had non-heat-treatment performance, which was greater than the ordinary die-cast aluminum alloys with a similar composition. The tensile strength of the aluminum alloys reached up to 310 MPa before heat treatment.

scholarly journals TEM study of precipitation in a Nial-3Ti-0.5Hf single-crystal alloy

1996 ◽  
Vol 54 ◽  
pp. 998-999
Author(s):  
A. Garg ◽  
R. D. Noebe ◽  
J. M. Howe ◽  
A. W. Wilson ◽  
V. Levit
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Transmission Electron Microscopy ◽  
Single Crystal ◽  
Argon Atmosphere ◽  
Second Phase ◽  
Directionally Solidified ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated

Three directionally solidified NiAl single-crystal alloys, NiAl-3Ti, NiAl-0.5Hf and NiAl-3Ti-0.5Hf (at.%), were grown by a Bridgeman technique using high purity alumina crucibles. The ingots were homogenized for 32h at 1644 K followed by aging for 6h at 1255 K and finally furnace cooled under an argon atmosphere. This heat treatment was found to be very effective in dissolving Hf-rich interdendritic particles that were present in the as-cast structure, and at the same time it produced fine second-phase precipitates in the alloy.Samples for transmission electron microscopy (TEM) were prepared from 3 mm diameter cylinders electro-discharge machined from the heat-treated ingots. Slices sectioned from the cylinders were mechanically ground and electrochemically thinned in a twin-jet Tenupol-3 polisher. Microstructural and energy-dispersive X-ray spectroscopy (EDXS) studies were conducted in a Philips 400T TEM equipped with a double tilt goniometer and a KEVEX Si/Li X-ray detector.

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