scholarly journals Martensite aging in 〈001〉 oriented Co49Ni21Ga30 single crystals in tension

2018 ◽  
Vol 11 (02) ◽  
pp. 1850024 ◽  
Author(s):  
C. Lauhoff ◽  
P. Krooß ◽  
D. Langenkämper ◽  
C. Somsen ◽  
G. Eggeler ◽  
...  
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Neutron Diffraction ◽  
Single Crystals ◽  
Elevated Temperatures ◽  
Transformation Temperatures ◽  
Chemical Order ◽  
Compressive Loads ◽  
The Impact ◽  
Tension Compression Asymmetry

Co–Ni–Ga high-temperature shape memory alloys (HT-SMAs) are well-known candidate materials for damping applications at elevated temperatures. Recent studies showed that upon heat treatment in stress-induced martensite under compressive loads transformation temperatures can be increased significantly, qualifying Co–Ni–Ga for HT-actuation. The increase in transformation temperatures is related to a change in chemical order recently validated via neutron diffraction experiments. Since SMAs show distinct tension–compression asymmetry in terms of theoretical transformation strains and bearable stresses, understanding the impact of martensite aging in tension is crucial for future applications. The current results indicate that martensite aging in tension provides for a further improvement in functional properties.

Tension - Compression Asymmetry in Co49Ni21Ga30 High-Temperature Shape Memory Alloy Single Crystals

2013 ◽  
Vol 738-739 ◽  
pp. 82-86 ◽  
Author(s):  
Thomas Niendorf ◽  
Jayaram Dadda ◽  
Jan Lackmann ◽  
James A. Monroe ◽  
Ibrahim Karaman ◽  
...  
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Stress State ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Single Crystals ◽  
Stress Level ◽  
Elevated Temperatures ◽  
Stress States ◽  
Tension Compression Asymmetry

This paper reports on the tension-compression asymmetry of [001]-oriented Co49Ni21Ga30 single crystals at elevated temperatures. Maximum strains of -4.8 % and 8.6 % in compression and tension, respectively, were found. A linear Clausius-Clapeyron relationship was observed for both stress-states where the smaller slope in tension resulted in a significant increase of the phase transformation temperatures with stress, which reached 180 °C under a constant stress level of 150 MPa. In addition, the material demonstrated a large pseudoelastic temperature range of about 300 °C under both stress state conditions. The results in this study unequivocally indicate the potential of these alloys for applications where elevated temperatures and stress levels prevail.

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 effect of thermal exposure on precipitation of Ti3Al(C,N) in Ti-48Al-IV-0.2C

1992 ◽  
Vol 50 (1) ◽  
pp. 22-23
Author(s):  
W.T. Donlon ◽  
W.E. Dowling ◽  
C.E. Cambell ◽  
J.E. Allison
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Titanium Aluminides ◽  
Elevated Temperatures ◽  
Volume Fraction ◽  
Weight Ratio ◽  
Thermal Exposure ◽  
Treatment Temperature ◽  
Field Samples ◽  
Structural Applications

Titanium aluminides are attractive candidates for high temperature structural applications because of their high strength to weight ratio at elevated temperatures. The microstructure of these alloys consists of γ-TiAl (distorted L10 structure) , plus α2-Ti3Al (ordered DO19 structure). Varying the heat treatment temperature and cooling rate of these alloys alters the volume fraction and distribution of the γ and α2 phases. This has significant effects on the room temperature ductility. In addition, precipitation of carbides has been observed during high temperature exposure. The effect of these precipitates on the mechanical properties has yet to be determined.Figure 1 shows the general microstructure that was used for this investigation. TEM foils were prepared by electropolishing using 5% perchloric, 35% 1-butanol, 60% methanol at -40°C. No precipitates were found following heat treatment in the γ+α phase field. Samples approximately 20 mm square were thermally exposed to temperatures between 625° and 1000°C for times between 1 and 2000 hours.

HPM X-750

Alloy Digest ◽  
2006 ◽  
Vol 55 (6) ◽  
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Physical Properties ◽  
Elevated Temperatures ◽  
Alloy Composition ◽  
Heat Treating ◽  
Chromium Alloy ◽  
Nickel Chromium ◽  
Temperature Performance ◽  
Wide Range

Abstract HPM X-750 is a precipitation-hardenable nickel-chromium alloy that is well suited for a wide range of corrosive and oxidizing environments where strength must be maintained to elevated temperatures. The alloy composition provides a product that performs well at elevated temperatures up to 700 deg C (1300 deg F). The strength can be increased by heat treatment. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance as well as forming, heat treating, and joining. Filing Code: Ni-638. Producer or source: Hamilton Precision Metals.

ARMCO PH 15-7Mo STAINLESS STEEL

Alloy Digest ◽  
1997 ◽  
Vol 46 (8) ◽  
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Elevated Temperatures ◽  
High Strength ◽  
Heat Treating ◽  
Good Corrosion Resistance ◽  
Temperature Performance ◽  
Minimal Distortion

Abstract Armco PH 15-7 Mo stainless steel is a Cr-Ni-Mo-Al semi-austenitic stainless steel. It is heat treatable to high strength and hardness, maintains good corrosion resistance, and undergoes minimal distortion from heat treatment. The alloy has applications in the aerospace and other industries where high strength at elevated temperatures is required. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-693. Producer or source: Armco Inc., Specialty Steels Division.

scholarly journals Microstructure Evolution and Mechanical Properties of 0.4C-Si-Mn-Cr Steel during High Temperature Deformation

Materials ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 172 ◽  
Author(s):  
Fei Zhang ◽  
Yang Yang ◽  
Quan Shan ◽  
Zulai Li ◽  
Jinfeng Bi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
High Temperature ◽  
Impact Toughness ◽  
Microstructure Evolution ◽  
Cast Steel ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Grain Sizes ◽  
The Impact

Herein, the effects of height-diameter ratios (H/D) on the microstructure evolution and mechanical properties of 0.4C-Si-Mn-Cr steel during high temperature deformation are reported. The compression experiments were performed on steel samples using Gleeble to obtain a reasonable deformation temperature, and the degree of deformation was assessed in the range of 1.5 to 2.0 H/D via forging. The forged specimens were quenched using the same heat treatment process. The hardness and impact toughness of the steel samples were tested before and after heat treatment. Grain sizes gradually increased with an increase in the compression temperature from 950 °C to 1150 °C, and the grain sizes decreased with an increase in H/D. The microstructure of the steel samples contained pearlite, bainite, martensite, and retained austenite phase. The microstructure after forging was more uniform and finer as compared to that of as-cast steel samples. The hardness and impact toughness of the steel samples were evaluated after forging; hardness first increased and then decreased with an increase in H/D, while the impact toughness continuously increased with an increase in H/D. Hence, the microstructure and properties of steel could be improved via high temperature deformation, and this was primarily related to grain refinement.

Features of heat treatment of a new steel for the manufacture of hot deformation dies

2021 ◽  
pp. 54-60
Author(s):  
S. E. Krylova ◽  
◽  
E. V. Romashkov ◽  
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Elevated Temperatures ◽  
Heat Exposure ◽  
Microalloyed Steels ◽  
Carbide Phases ◽  
Rational Mode ◽  
Spheroidizing Annealing ◽  
And Behavior ◽  
Combined Cooling

The influence of heat treatment parameters on the structure and properties of the promising 70Cr3Mn2WTiB die steel, which is offered for the manufacture of mold parts for aluminum alloy injection molding machines, is revealed. A rational mode of thermal hardening is recommended for the developed steel, including spheroidizing annealing at a temperature of 780 °C with combined cooling; quenching at 1000 °C with oil cooling; high-temperature tempering at 550–600 °C with cooling in calm air. The structure formation and behavior of carbide phases in microalloyed steels at various stages of heat treatment are evaluated. The features of phase transformations and the mechanism of dispersion hardening during high-temperature tempering that provide the required set of mechanical and technological properties are determined. The influence of heat treatment modes on mechanical and operational properties under cyclic loading and heat exposure at normal and elevated temperatures is evaluated. Fractographic studies of zones of cyclic and static crack growth in fractures of samples after testing for crack resistance under cyclic and static loading were performed. The main regularities of changes in the thermal structural stability of chromium steels under cyclic temperature and force influences, depending on the nature of alloying and heat treatment modes, are substantiated, which made it possible to reasonably recommend the developed 70Cr3Mn2WTiB steel for implementation.

BOHNALITE J

Alloy Digest ◽  
1954 ◽  
Vol 3 (1) ◽  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Shear Strength ◽  
Aluminum Alloy ◽  
High Temperature ◽  
Elevated Temperatures ◽  
Heat Treating ◽  
Permanent Mold ◽  
Temperature Performance ◽  
Copper Aluminum

Abstract BOHNALITE J is a high-copper aluminum alloy suitable for permanent mold and sand casting. It responds to heat treatment to produce high mechanical properties. It retains its strength well and has other excellent properties at elevated temperatures. Its bearing properties are also good. This datasheet provides information on composition, physical properties, hardness, tensile properties, and compressive and shear strength as well as fatigue. It also includes information on high temperature performance as well as heat treating, machining, and joining. Filing Code: Al-12. Producer or source: Bohn Aluminum & Brass Corporation.

MST 2.5Al-16V

Alloy Digest ◽  
1960 ◽  
Vol 9 (2) ◽  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Shear Strength ◽  
High Temperature ◽  
Elevated Temperatures ◽  
Base Alloy ◽  
Heat Treating ◽  
Age Hardening ◽  
Temperature Performance ◽  
Hardening Heat Treatment

Abstract MST 2.5A1-16V is a titanium-base alloy having a favorable combination of strength, formability and resistance to creep at elevated temperatures. It responds to an age-hardening heat treatment. This datasheet provides information on composition, physical properties, elasticity, tensile properties, and compressive and shear strength as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ti-24. Producer or source: Mallory-Sharon Metals Company.

Effect of Temperature Dropping during Solution Treatment in Rejuvenation Heat Treatment and its Long-Term Heating Simulation on Microstructures of Nickel Base Alloy, Udimet 520

2017 ◽  
Vol 891 ◽  
pp. 25-32
Author(s):  
Kritsayanee Saelor ◽  
Panyawat Wangyao
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Elevated Temperatures ◽  
Turbine Blades ◽  
Solution Treatment ◽  
Effect Of Temperature ◽  
Solution Temperature ◽  
Nickel Base ◽  
Low Precipitation

Udimet 520 is a low precipitation strengthened nickel-based superalloy, which was designed and developed to be gas turbine blades at elevated temperatures. However, after long-term service under high stresses and temperatures, the microstructure of the turbine blades could be continually degraded. Therefore, the mechanical properties could be worse than the new ones. The rejuvenation heat treatment of degraded turbine blades, which were made of cast Udimet 520, was following by solution treatment at 1,121oC / 4 hours and then double aging processes including primary aging at 843 oC / 24 hours and secondary aging at 760oC / 16 hours, respectively. However, in practical reheat treatment processes, the temperature during solution treatment could be dropped by error or malfunction of high temperature heating furnace because the furnace has to be operated continually at very high temperature for very long time resulting in final reheat treated microstructures in many nickel base superalloys. To simulate this effect, the droppings of temperature during solution treatment are chosen and performed for 3 levels; 840oC, 800oC and 760oC, which could happen in practical working then heated up again immediately to solution temperature level. The maximum number of temperature dropping during the single solution treatment is up to 3 times. Received results show that the effect of temperature dropping during solution treatment has influenced on the final rejuvenated microstructures slightly due to the low precipitation behavior of the alloy. The long term heating at 800oC and 900oC / 1000 hours provided much effect in gamma prime particle coarsening.

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