Rejuvenation Heat Treatments and Their Role in the Repair of IN738 Turbine Components

2002 ◽  
Author(s):  
Warren M. Miglietti ◽  
Rich Curtis ◽  
John Helm
Keyword(s):  
Mechanical Properties ◽  
Turbine Blades ◽  
Stress Rupture ◽  
Repair Process ◽  
Heat Treatments ◽  
Turbine Engine ◽  
Heat Treated ◽  
Before And After ◽  
Metal Microstructure ◽  
Engine Components

The thermal processing of turbine engine components is a critical step in the repair and rejuvenation of turbine section hardware to ensure optimal performance and reliability. In the repair process, the thermal process regime must meet the following requirements; improving the weldability of the alloy prior to the repair process (if necessary), returning the microstructure of the alloy to a solutioned state prior to precipitation hardening the alloy, and an aging cycle in order to achieve optimal mechanical properties for the alloy. This paper will focus on the criticality of each step and discuss the typical mechanical properties seen after engine service and the repair process. We will show the importance of these steps and how they will ultimately effect the repair of the hot section component. For almost three decades, gas turbine original equipment manufacturers (OEM’s) have cast high-pressure turbine blades/buckets from In738 Ni-base superalloys. Although significant turbine experience has been gained in the use of this material, little or no standardization of repair heat treatments has been established in the industry. Currently OEM’s and component repair shops utilize a variety of refurbishment heat treatments, all targeted at achieving maximum restoration of mechanical properties and base metal microstructure. This paper also summarizes the results of stress rupture testing of service-run material both before and after six different rejuvenation heat treatments. Microstructures in the service-run and heat-treated conditions are also characterized.

scholarly journals Effects of equal channel angular pressing and heat treatments on the microstructures and mechanical properties of selective laser melted and cast AlSi10Mg alloys

2021 ◽  
Vol 21 (3) ◽  
Author(s):  
Przemysław Snopiński ◽  
Mariusz Król ◽  
Marek Pagáč ◽  
Jana Petrů ◽  
Jiří Hajnyš ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Equal Channel Angular Pressing ◽  
Heat Treatments ◽  
Electron Backscattered Diffraction ◽  
Angular Pressing ◽  
Low Temperature Annealing ◽  
Transmission Electron ◽  
Before And After ◽  
The Impact

AbstractThis study investigated the impact of the equal channel angular pressing (ECAP) combined with heat treatments on the microstructure and mechanical properties of AlSi10Mg alloys fabricated via selective laser melting (SLM) and gravity casting. Special attention was directed towards determining the effect of post-fabrication heat treatments on the microstructural evolution of AlSi10Mg alloy fabricated using two different routes. Three initial alloy conditions were considered prior to ECAP deformation: (1) as-cast in solution treated (T4) condition, (2) SLM in T4 condition, (3) SLM subjected to low-temperature annealing. Light microscopy, transmission electron microscopy, X-ray diffraction line broadening analysis, and electron backscattered diffraction analysis were used to characterize the microstructures before and after ECAP. The results indicated that SLM followed by low-temperature annealing led to superior mechanical properties, relative to the two other conditions. Microscopic analyses revealed that the partial-cellular structure contributed to strong work hardening. This behavior enhanced the material’s strength because of the enhanced accumulation of geometrically necessary dislocations during ECAP deformation.

scholarly journals Electron Beam Melting of Ti-6Al-4V Lattice Structures; Correlation between Post Heat Treatment and Mechanical Properties

2021 ◽  
Author(s):  
Giuseppe Del Guercio ◽  
Manuela Galati ◽  
Abdollah Saboori
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Computer Aided Design ◽  
Mechanical Performance ◽  
Industrial Applications ◽  
Heat Treatments ◽  
Layer By Layer ◽  
Lattice Structures ◽  
Heat Treated ◽  
Aided Design

Abstract Additive Manufacturing processes are considered advanced manufacturing methods. It would be possible to produce complex shape components from a Computer-Aided Design model in a layer-by-layer manner. Lattice structures as one of the complex geometries could attract lots of attention for both medical and industrial applications. In these structures, besides cell size and cell type, the microstructure of lattice structures can play a key role in these structures' mechanical performance. On the other hand, heat treatment has a significant influence on the mechanical properties of the material. Therefore, in this work, the effect of the heat treatments on the microstructure and mechanical behaviour of Ti-6Al-4V lattice structures manufactured by EBM was analyzed. The main mechanical properties were compared with the Ashby and Gibson model. It is very interesting to notice that a more homogeneous failure mode was found for the heat-treated samples. The structures' relative density was the main factor influencing their mechanical performance of the heat-treated samples. It is also found that the heat treatments were able to preserve the stiffness and the compressive strength of the lattice structures. Besides, an increment of both the elongation at failure and the absorbed energy was obtained after the heat treatments. Microstructure analysis of the heat-treated samples confirms the increment of ductility of the heat-treated samples with respect to the as-built one.

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.

Advanced Welding Materials and Technologies for Repair of Turbine Engine Components Manufactured of High Gamma Prime Nickel Based Superalloys

2018 ◽  
Author(s):  
Alexandre Gontcharov ◽  
Yuan Tian ◽  
Paul Lowden ◽  
Robert Tollett ◽  
Mathieu Brochu
Keyword(s):  
Rupture Strength ◽  
Solidus Temperature ◽  
Stress Rupture ◽  
Melting Behavior ◽  
Turbine Engine ◽  
Weld Microstructure ◽  
Gamma Prime ◽  
High Gamma ◽  
Engine Components ◽  
Welding Materials

The current study reports on modification of conventional welding materials with titanium, boron and silicon to enhance weldability by reducing the solidus temperature and promoting the formation of low temperature eutectics. Melting behavior, weld microstructure, tensile and stress rupture strength are reported for several alloy compositions. Some examples of repairs of IGT and aero HPT blades using the materials and technologies are provided.

Hot Isostatic Pressing of Titanium Alloys for Turbine Engine Components

1973 ◽  
Author(s):  
G. H. Harth
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
Powder Processing ◽  
State Of The Art ◽  
Hot Isostatic Pressing ◽  
Turbine Engine ◽  
Isostatic Pressing ◽  
Powder Consolidation ◽  
Powder Type ◽  
Engine Components

This paper presents the state-of-the-art knowledge concerning the application of powder metallurgy to the fabrication of titanium alloy turbine engine components. The effect of powder type, powder processing, and method of powder consolidation on the mechanical properties and microstructures of P/M parts it discussed. The advantages of using hot isostatic pressing (HIP) in producing engine components is outlined.

The Microstructure and Compression Behavior of Multi-Step Forging Ti-45Al-8Nb Alloy after Annealing at 1100 °C

2013 ◽  
Vol 747-748 ◽  
pp. 111-114
Author(s):  
Lin Song ◽  
Xiang Jun Xu ◽  
Jun Pin Lin ◽  
Lai Qi Zhang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Annealing Treatment ◽  
Air Cooling ◽  
Test Machine ◽  
Compressive Properties ◽  
Compression Behavior ◽  
Microstructure Change ◽  
Heat Treated ◽  
Before And After

Effects of annealing treatment on microstructure and the compressive properties of hot-worked Ti-45Al-8Nb-(W, B, Y) alloy were investigated. Microstructure of the extrusion plus multi-step forging pancake before and after heat treatment was analyzed by SEM and TEM, respectively. The annealing was conducted by holding samples at 1100°C for 2hrs, and followed by air cooling and furnace cooling. The mechanical properties were measured by Instron test machine. The microstructure evolution during compressive deformation was analyzed by TEM. The results showed that after the annealing the microstructure change could not be observed under SEM but can be observed under TEM. Many dislocation clusters were removed by heat treatment. The heat treated samples had similar compression behaviors with the pancake. TEM investigation showed that the numerous twin intersections occured in γ matrix during compression. The twin spaces tended to decrease as the deformation and the intersection increasing.

Micro-Chemistry and Mechanical Behaviour of Ti6Al4V-SiCf Composite Produced by HIP for Aeronautical Applications

2011 ◽  
Vol 678 ◽  
pp. 23-47 ◽  
Author(s):  
Paolo Deodati ◽  
Riccardo Donnini ◽  
Saulius Kaciulis ◽  
Majid Kazemian-Abyaneh ◽  
Alessio Mezzi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Turbine Blades ◽  
Hot Isostatic Pressing ◽  
Heat Treatments ◽  
Maximum Temperature ◽  
Indentation Tests ◽  
Service Conditions ◽  
Increasing Temperature

The paper reports the results of an extensive characterization of the Ti6Al4V-SiCfcomposite produced by hot isostatic pressing (HIP) to assess its capability to withstand the in-service conditions of turbine blades operating at middle temperatures in aeronautical engines. The microstructure of composite, in as-fabricated condition and after long-term heat treatments (up to 1,000 hours) in the temperature range 673-873 K, has been investigated by means of different techniques. Particular attention was paid to the micro-chemical evolution of fibre-matrix interface which is scarcely affected also by the most severe heat treatments examined here. This leads to stable mechanical properties as evidenced by hardness, tensile and FIMEC instrumented indentation tests. Therefore, the composite can operate at the maximum temperature (873 K) foreseen for its aeronautical applications without remarkable modifications of its microstructure and degradation of mechanical properties. The mechanical characterization has been completed by internal friction and dynamic modulus measurements carried out both at constant and increasing temperature, from 80 to 1173 K.

scholarly journals The Effect of Cooling Rate on Mechanical Properties of Carbon Steel (St 35)

2014 ◽  
Vol 7 (1) ◽  
pp. 109-118
Author(s):  
Jenan Mohammed Nagie
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Grain Size ◽  
Carbon Steel ◽  
Cooling Rate ◽  
Experimental Results ◽  
Heat Treated ◽  
Before And After ◽  
Water Media ◽  
The Relationship

This paper is aimed to study the effect of cooling rate on mechanical properties of Steel 35. Specimens prepared to apply tensile, torsion, impact and hardness tests.Many prepared specimens heat treated at (850ºC) for one hour and subsequently were cooled by three different media [Water-Air-furnace] to show the effect of Medias cooling rate on mechanical properties. Microstructures of all specimens examined before and after heat treatment by an optical microscopy.To figure the phases obtained after heat treatment and its effect on the mechanical properties Experimental results have shown that the microstructure of steel can be changed and significantly improved by varying line cooling rate thus, improving one property will effect on the others because of the relationship between all properties.In water media tensile, torsion and hardness improved while impact results reduced. Air media contributed in improving most of the mechanical properties because of grain size homogeneity. At furnace media ductility and impact improved

Three Point Bend Performance of Solutionized, Die Quenched and Heat Treated AA7075 Beam Members

2014 ◽  
Vol 794-796 ◽  
pp. 431-436 ◽  
Author(s):  
Alexander Bardelcik ◽  
Alexandre Bouhier ◽  
Michael J. Worswick
Keyword(s):  
Mechanical Properties ◽  
Peak Load ◽  
Natural Aging ◽  
High Strength ◽  
Total Elongation ◽  
Strength Properties ◽  
Heat Treatments ◽  
Forming Process ◽  
Heat Treated ◽  
Point Bend

To overcome the low room temperature formability of AA7075-T6 aluminum sheet, without sacrificing the high strength properties of this alloy, a hat section beam member was formed and quenched within a cold die immediately after a 20 minute solutionizing treatment. Natural aging for 24 hours followed the forming process which was then followed by various heat treatments that included a typical precipitation hardening (PH) and industrial paint bake (PB) temperature-time treatment. Tensile specimens were extracted from the beams to evaluate their mechanical properties. When compared to the as-received AA7075-T6 mechanical properties, the beams heat treated with the PH, PHPB and PB treatment resulted in a 5%, 13% and 20% reduction in ultimate tensile strength respectively. A similar trend was shown for the yield strength measurements. There was little effect of the heat treatments on the total elongation, with the PH condition showing a slight improvement. A backing plate was riveted to the beams and a quasi-static 3 point bend test was conducted to evaluate the crush performance. The peak load for the PH, PHPB and PB beams was 9.2, 8.5 and 7.3 kN respectively, but the calculated energy-displacement (or energy absorption) curves were similar for the PH and PHPB parts due to a more ductile fracture behavior for the PHPB material condition.

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