Directionally Solidified DS CM 247 LC—Optimized Mechanical Properties Resulting From Extensive γ′ Solutioning

1985 ◽  
Author(s):  
G. L. Erickson ◽  
K. Harris ◽  
R. E. Schwer
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Turbine Blade ◽  
Incipient Melting ◽  
Directionally Solidified ◽  
Operating Condition ◽  
C 50

Complete coarse γ′ and greater than 90% eutectic γ-γ′ solutioning, without incipient melting, is demonstrated for the DS CM 247 LC superalloy. This unusual capability for this advanced Ni-base turbine blade and vane material results in considerable mechanical properties enhancement, with the DS alloy capability being near to current single crystal superalloys in the 345–207 MPa, 871°C–982°C (50–30 ksi, 1600°F–1800°F) operating condition. Microstructural features are detailed correlating strength and alloy stability.

scholarly journals The Microstructure, Mechanical Properties and Coatability of Diffusion Brazed CMSX-4 Single Crystal

1996 ◽  
Author(s):  
Warren M. Miglietti ◽  
Ros C. Pennefather
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Elevated Temperatures ◽  
Aluminide Coating ◽  
Turbine Blades ◽  
Stress Rupture ◽  
Directionally Solidified ◽  
Diffusion Brazing ◽  
Brazed Joints ◽  
Boride Phases

Diffusion brazing is a joining process utilized both in the manufacture and repair of turbine blades and vanes. CMSX-4 is an investment cast, single crystal, Ni-based superalloy used for turbine blading and vanes, and has enhanced mechanical properties at elevated temperatures when compared to equiaxed, directionally solidified and first generation single crystal superalloys. The objective of this work was to develop a diffusion brazing procedure to achieve reliable joints in the manufacture of a hollow turbine blade (for a prototype engine in South Africa), and to verify the coatability of the diffusion brazed joints. Two commercially available brazing filler metals of composition Ni-15Cr-3.5B and Ni-7Cr-3Fe-4.5Si-3.2B-0.06C and a proprietary (wide gap) braze were utilized. With the aim of eliminating brittle centre-line boride phases, the effects of temperature and time on the joint microstructure were studied. Once the metallurgy of the joint was understood, tensile and stress rupture tests were undertaken, the latter being one of the severest tests to evaluate joint strength. The results demonstrated that the diffusion brazed joints could satisfy the specified stress rupture criterion of a minimum of 40 hrs life at 925 °C and 200 MPa. After mechanical property evaluations, an investigation into the effects of a low temperature high activity (LTHA) pack aluminide coating and a high temperature low activity (HTLA) pack aluminide coating on the braze joints was undertaken. The results showed that diffusion brazed joints could be readily coated.

scholarly journals Microstructural Investigations of Ni-Based Superalloys by Directional Solidification Quenching Technique

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4265
Author(s):  
Tobias Wittenzellner ◽  
Shieren Sumarli ◽  
Helge Schaar ◽  
Fu Wang ◽  
Dexin Ma ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Cooling Rate ◽  
Electron Backscatter Diffraction ◽  
Local Concentration ◽  
Directionally Solidified ◽  
Polycrystalline Structure ◽  
Characterization Methods ◽  
Solidification Mechanism ◽  
Cast Microstructure

The improvement of the mechanical properties of Ni-based superalloys is achieved in most cases by modifying the chemical composition. Besides that, the processing can be modified to optimize the as-cast microstructure with regard to the mechanical properties. In this context, the present study highlights the solidification mechanism of several Ni-based superalloys by conducting experiments using a modified, laboratory-scale Bridgman-Stockbarger furnace. In that context, the single-crystal rods are partially melted, directionally solidified and quenched sequentially. Several characterization methods are applied to further analyze the influence of the alloying elements and the variation of the withdrawal rate on the as-cast microstructure. Four stages of solidification are distinguished whereby the morphology observed in the different stages mainly depends on the cooling rate and the local concentration of the carbide forming elements. The effect of carbide precipitation and the effect on the as-cast microstructure is investigated by employing energy dispersive X-ray spectrometry (EDX) and electron backscatter diffraction (EBSD) analysis techniques. A local polycrystalline structure is observed in the single-crystal system as consequence of the influence of the carbon content and the cooling rate. The present work aims to develop strategies to suppress the formation of the polycrystalline structure to maintain the single-crystal microstructure.

scholarly journals Development of the Single Crystal Alloys CM SX-2 and CM SX-3 for Advanced Technology Turbine Engines

1983 ◽  
Author(s):  
K. Harris ◽  
G. L. Erickson ◽  
R. E. Schwer
Keyword(s):  
Heat Treatment ◽  
Single Crystal ◽  
Turbine Blade ◽  
Solution Heat Treatment ◽  
Creep Rupture ◽  
Advanced Technology ◽  
Thin Wall ◽  
Incipient Melting ◽  
Practical Solution ◽  
Oxidation And Corrosion

Two complementary single crystal alloys have been developed from the MAR-M-247 composition, with the objectives of providing high creep-rupture strength, excellent oxidation resistance, good castability, practical solution heat-treatment ranges, high incipient melting points, and stable microstructures. The alloys, CM SX-2 and CM SX-3, are turbine blade and vane alloys, with CM SX-3 showing improved coated oxidation and corrosion resistance. Foundry performance characteristics studied using ten different single crystal casting processes to produce both solid and complex cored, thin-wall turbine blade and vane components were: “freckling” sensitivity, spurious grain formation, microporosity, and alloy/ceramic core reactions. Practical solution heat-treatment ranges (difference between the γ′ solvus and the incipient melting temperatures) have been established and vary from 45–50°F for CM SX-3 and 50–55°F for CM SX-2 measured without prior homogenization treatments. Extensive machined-from-blade (MFB) mechanical property work is reported. Alloy stability investigations were undertaken using prior tested MFB stress-rupture specimens. Environmental evaluations using both bare and coated single crystal specimens, subjected to separate cyclic/dynamic oxidation, and corrosion testing in burner-type rigs are also reviewed. A new γ′ microstructure/heat-treatment technology has been found to be particularly applicable to CM SX-2 and CM SX-3 alloys, because of their low γ/γ′ mismatch and suitable γ′ chemistry. This technology further increases the creep-rupture capability of both alloys by 10–40°F, depending on test temperature.

The Influence of Crystal Orientation on the Elastic Stresses of a Single Crystal Nickel-Based Turbine Blade

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Michael W. R. Savage
Keyword(s):  
Single Crystal ◽  
Turbine Blade ◽  
Fatigue Resistance ◽  
Crystal Orientation ◽  
Turbine Blades ◽  
Casting Process ◽  
Directionally Solidified ◽  
Element Analysis ◽  
Angle Variation ◽  
Elastic Stresses

Single crystal nickel-based turbine blades are directionally solidified during the casting process with the crystallographic direction [001] aligned with the blade stacking axis. This alignment is usually controlled within 10 deg, known as the Primary angle. The rotation of the single crystal about the [001] axis is generally not controlled and this is known as the Secondary angle. The variation in Primary and Secondary angles relative to the blade geometry means that the stress response from blade to blade will be different, even for the same loading conditions. This paper investigates the influence of single crystal orientation on the elastic stresses of a CMSX-4 turbine blade root attachment using finite element analysis. The results demonstrate an appreciable variation in elastic stress when analyzed over the controlled Primary angle, and are further compounded by the uncontrolled Secondary angle. The maximum stress range will have a direct impact on the fatigue resistance of the turbine blade. By optimizing the Secondary angle variation the elastic stresses can be reduced, giving the potential to enhance the fatigue resistance of the turbine blade.

The Influence of Crystal Orientation on the Elastic Stresses of a Single Crystal Nickel-Based Turbine Blade

2011 ◽  
Author(s):  
Michael W. R. Savage
Keyword(s):  
Single Crystal ◽  
Turbine Blade ◽  
Fatigue Resistance ◽  
Crystal Orientation ◽  
Turbine Blades ◽  
Casting Process ◽  
Directionally Solidified ◽  
Element Analysis ◽  
Angle Variation ◽  
Elastic Stresses

Single crystal nickel-based turbine blades are directionally solidified during the casting process with the crystallographic direction [001] aligned with the blade stacking axis. This alignment is usually controlled within 10°, known as the Primary angle. The rotation of the single crystal about the [001] axis is generally not controlled and this is known as the Secondary angle. The variation in Primary and Secondary angles relative to the blade geometry means that the stress response from blade to blade will be different, even for the same loading conditions. This paper investigates the influence of single crystal orientation on the elastic stresses of a CMSX-4 turbine blade root attachment using finite element analysis. The results demonstrate an appreciable variation in elastic stress when analysed over the controlled Primary angle, and are further compounded by the uncontrolled Secondary angle. The maximum stress range will have a direct impact on the fatigue resistance of the turbine blade. By optimizing the Secondary angle variation the elastic stresses can be reduced, giving the potential to enhance the fatigue resistance of the turbine blade.

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

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