scholarly journals Strength of Materials at Elevated Temperatures. Analysis of Intergranular Cracking for Incoloy 908 during a Heat Treatment.

1999 ◽  
Vol 48 (2) ◽  
pp. 152-158
Author(s):  
Kenji KIKUCHI ◽  
Takashi KATO ◽  
Makoto SUGIMOTO ◽  
Kohtaro ISHIO ◽  
Kiyoshi FUKAYA ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Elevated Temperatures ◽  
Intergranular Cracking ◽  
Strength Of Materials

High-Temperature Instability of A Cr2Nb-Nb(Cr) Microlaminate Composite

1996 ◽  
Vol 54 ◽  
pp. 374-375
Author(s):  
M. Larsen ◽  
R.G. Rowe ◽  
D.W. Skelly
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
High Temperature ◽  
Elevated Temperatures ◽  
Aircraft Engine ◽  
Lattice Parameter ◽  
Microstructural Stability ◽  
Elevated Temperature Strength ◽  
Cross Sectional ◽  
Bcc Structure

Microlaminate composites consisting of alternating layers of a high temperature intermetallic compound for elevated temperature strength and a ductile refractory metal for toughening may have uses in aircraft engine turbines. Microstructural stability at elevated temperatures is a crucial requirement for these composites. A microlaminate composite consisting of alternating layers of Cr2Nb and Nb(Cr) was produced by vapor phase deposition. The stability of the layers at elevated temperatures was investigated by cross-sectional TEM.The as-deposited composite consists of layers of a Nb(Cr) solid solution with a composition in atomic percent of 91% Nb and 9% Cr. It has a bcc structure with highly elongated grains. Alternating with this Nb(Cr) layer is the Cr2Nb layer. However, this layer has deposited as a fine grain Cr(Nb) solid solution with a metastable bcc structure and a lattice parameter about half way between that of pure Nb and pure Cr. The atomic composition of this layer is 60% Cr and 40% Nb. The interface between the layers in the as-deposited condition appears very flat (figure 1). After a two hour, 1200 °C heat treatment, the metastable Cr(Nb) layer transforms to the Cr2Nb phase with the C15 cubic structure. Grain coarsening occurs in the Nb(Cr) layer and the interface between the layers roughen. The roughening of the interface is a prelude to an instability of the interface at higher heat treatment temperatures with perturbations of the Cr2Nb grains penetrating into the Nb(Cr) layer.

The Effects of Quenching and Tempering Treatment on the Hardness and Microstructures of a Cold Work Steel

2019 ◽  
Vol 4 (1) ◽  
pp. 286-294
Author(s):  
László Tóth ◽  
Réka Fábián
Keyword(s):  
Heat Treatment ◽  
Retained Austenite ◽  
Elevated Temperatures ◽  
Cryogenic Treatment ◽  
Cold Work ◽  
Chromium Steel ◽  
Primary Carbide ◽  
Tempering Temperature ◽  
Tempering Treatment ◽  
Primary Carbides

The X153CrMoV12 ledeburitic chromium steel characteristically has high abrasive wear resistance, due to their high carbon and high chromium contents with a large volume of carbides in the microstructure. This steel quality has high compression strength, excellent deep hardenability and toughness properties, dimensional stability during heat treatment, high resistance to softening at elevated temperatures. The higher hardness of cryogenic treated samples in comparison with conventional quenched samples mean lower quantity of retained austenite as at samples quenched to room temperature and tempered in similar condition. In the microstructure of samples were observed that the primary carbide did not dissolve at 1070°C and their net structure have not been changed during to heat treatment. During to tempering at high temperature the primary carbides have become more and more rounded. After low tempering temperature in martensite were observed some small rounded carbides also, increasing the tempering temperature the quantity of finely dispersed carbides increased, which result higher hardness. The important issues in heat treatment of this steels are the reduction or elimination of retained austenite due to cryogenic treatment.

scholarly journals Effect of Heat Treatment on the As-Cast Microstructure and Hardness of NiSi3B2 Alloy

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 539
Author(s):  
Gonçalo M. Gorito ◽  
Aida B. Moreira ◽  
Pedro Lacerda ◽  
Manuel F. Vieira ◽  
Laura M. M. Ribeiro
Keyword(s):  
Heat Treatment ◽  
Elevated Temperatures ◽  
Casting Process ◽  
X Ray Diffraction ◽  
Heat Treated ◽  
Energy Dispersive Microanalysis ◽  
Eutectic Constituent ◽  
Backscattered Electron ◽  
Corrosion And Oxidation ◽  
Cast Microstructure

Cast Ni-Si-B alloys have the potential for high-temperature applications because of their high resistance to wear, impact, corrosion, and oxidation at elevated temperatures due to an appropriate balance of hard phases and austenite that ensures a good compromise between toughness and hardness. In this work, NiSi3B2 specimens, fabricated by the lost-wax casting process, were investigated. Given the complex multiphase cast microstructure, a differential scanning calorimeter (DSC-TGA) analysis was employed to characterize the reactions that occur during solidification and the resulting phases were characterized using scanning electron microscopy (SEM), with energy-dispersive microanalysis (EDS) and backscattered electron (BSE) image and X-ray diffraction (XRD). Due to the presence of hard phases, machining of the Ni-Si-B components can pose additional difficulties. Therefore, the conditions of the solution heat treatment, which might lead to the homogenization of the microstructure, consequently improving its machinability, were also investigated. The results of the heat-treated samples indicated that the dissolution of the eutectic constituent is accompanied by a significant decrease in the hardness (approximately 17%). It is important to emphasize that the solution heat treatments carried out reduced the hardness without affecting the percentage of borides, which will allow improving the machinability without adversely affecting the alloy performance in service.

Microstructure and Mechanical Properties of Ti-6Al-4V Manufactured by SLM

2015 ◽  
Vol 651-653 ◽  
pp. 677-682 ◽  
Author(s):  
Anatoliy Popovich ◽  
Vadim Sufiiarov ◽  
Evgenii Borisov ◽  
Igor Polozov
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Phase Composition ◽  
Mechanical Behavior ◽  
Ductile Fracture ◽  
Elevated Temperatures ◽  
Initial Material ◽  
Laser Melting ◽  
Microstructure And Mechanical Properties ◽  
Before And After

The article presents results of a study of phase composition and microstructure of initial material and samples obtained by selective laser melting of titanium-based alloy, as well as samples after heat treatment. The effect of heat treatment on microstructure and mechanical properties of specimens was shown. It was studied mechanical behavior of manufactured specimens before and after heat treatment at room and elevated temperatures as well. The heat treatment allows obtaining sufficient mechanical properties of material at room and elevated temperatures such as increase in ductility of material. The fractography of samples showed that they feature ductile fracture with brittle elements.

Microstructure Characterization of High Carbon Alloy from the Ni-Ta-Al-Co-Cr System / Charakterystyka Mikrostruktury Wysokowęglowego Stopu Z Układu Ni-Ta-Al-Co-Cr

2012 ◽  
Vol 57 (4) ◽  
pp. 937-941 ◽  
Author(s):  
P. Bała
Keyword(s):  
Heat Treatment ◽  
Wear Resistance ◽  
Elevated Temperatures ◽  
Chromium Content ◽  
Volume Fraction ◽  
High Carbon ◽  
Cr System ◽  
Primary Carbides ◽  
Cast Condition

In the present work results of investigations of the new high carbon alloy from the Ni-Ta-Al-Co-Cr system are presented. The alloy has been designed to have a good tribological properties at elevated temperatures. The chemical composition of this material was designed to obtain a matrix strengthening by the precipitation of γ’ phase (Ni3(Al,Ta)) and the primary carbides volume fraction above 25%. The primary carbides should remain stable in the microstructure, regardless of the heat treatment, in order to increase a wear resistance. The results of microstructure investigations in the as-cast condition are presented. The type of phases appearing in the microstructure was determined and their morphology described. The main microstructure components of the investigated Ni-based alloy with high carbon, cobalt and chromium content are: the γ phase, which constitutes a matrix, the γ’ phase, which occurs as fine globular precipitates and the primary Ta and Cr carbides (of MC and M7C3 type - respectively).

scholarly journals Microstructure and Properties of Selected Magnesium-Aluminum Alloys Prepared for SPD Processing Technology

2017 ◽  
Vol 62 (4) ◽  
pp. 2365-2370 ◽  
Author(s):  
L. Cizek ◽  
S. Rusz ◽  
O. Hilser ◽  
R. Śliwa ◽  
D. Kuc ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Aluminum Alloys ◽  
Magnesium Alloys ◽  
Elevated Temperatures ◽  
Deformation Behaviour ◽  
Az91 Alloy ◽  
Test Results ◽  
Treatment Conditions ◽  
Composition Modification ◽  
Cast Magnesium

AbstractA growing interest in wrought magnesium alloys has been noticed recently, mainly due to development of various SPD (severe plastic deformation) methods that enable significant refinement of the microstructure and – as a result – improvement of various functional properties of products. However, forming as-cast magnesium alloys with the increased aluminum content at room temperature is almost impossible. Therefore, application of heat treatment before forming or forming at elevated temperature is recommended for these alloys. The paper presents the influence of selected heat treatment conditions on the microstructure and the mechanical properties of the as-cast AZ91 alloy. Deformation behaviour of the as-cast AZ61 alloy at elevated temperatures was analysed as well. The microstructure analysis was performed by means of both light microscopy and SEM. The latter one was used also for fracture analysis. Moreover, the effect of chemical composition modification by lithium addition on the microstructure of the AZ31-based alloy is presented. The test results can be helpful in preparation of the magnesium-aluminum alloys for further processing by means of SPD methods.

scholarly journals The Influence of Post-Heat-Treatments on the Tensile Strength and Surface Hardness of Selective Laser Melted AlSi10Mg

2017 ◽  
Vol 370 ◽  
pp. 171-176 ◽  
Author(s):  
Leonhard Hitzler ◽  
Amandine Charles ◽  
Andreas Öchsner
Keyword(s):  
Heat Treatment ◽  
Tensile Strength ◽  
Precipitation Hardening ◽  
Elevated Temperatures ◽  
Surface Hardness ◽  
Heat Treatments ◽  
Age Hardening ◽  
Material Strength ◽  
Post Heat Treatment ◽  
Treatment Procedure

Recent investigations revealed major fluctuations in the material properties of selective laser melted AlSi10Mg, which corresponded with the varying precipitation-hardening state of the microstructure, caused by the differing dwell times at elevated temperatures. It was indicated that a subsequent heat treatment balances the age-hardening and results in a homogenized material strength. In order to further investigate this statement selective laser melted AlSi10Mg samples were subject to multiple post-heat-treatments. Subsequently, the surface hardness and tensile strength was determined and compared with the as-built results. The post-heat-treatment led to an arbitrary occurrence of rupture, indicating a successful homogenization, coupled with a remarkable improvement in ductility, but to the costs of a lowered tensile strength, which was highly dependent on the chosen heat-treatment procedure.

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