scholarly journals Powder Metallurgy Repair of Turbine Components

1992 ◽  
Author(s):  
K. A. Ellison ◽  
P. Lowden ◽  
J. Liburdi
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Powder Metallurgy ◽  
Filler Metal ◽  
Repair Process ◽  
Parent Material ◽  
High Temperature Alloys ◽  
Wide Gap ◽  
Mechanical Cleaning ◽  
Repair Techniques

An advanced powder metallurgy repair process called Liburdi Powder Metallurgy (LPM)1 has been developed for the repair, overlay or joining nickel and cobalt-based high temperature alloys. This process involves mechanical cleaning, followed by the application and consolidation of a filler metal powder which has substantially the same composition as the base metal, and produces joints with mechanical properties similar to those of the parent material. While previous activated braze or “wide-gap” repair processes have been limited to clearances of approximately 1 mm, the LPM technique has the ability to bridge larger gaps of over 5 mm. In addition, the LPM joints contain significantly lower concentrations of melting point depressants such as silicon and boron than conventional wide-gap repair techniques and exhibit superior microstructural features. The characteristics and typical applications of the LPM process for blade and vane repairs are highlighted and the results of laboratory and engine tests are discussed.

Powder Metallurgy Repair of Turbine Components

1994 ◽  
Vol 116 (1) ◽  
pp. 237-242 ◽  
Author(s):  
K. A. Ellison ◽  
P. Lowden ◽  
J. Liburdi
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Powder Metallurgy ◽  
Filler Metal ◽  
Repair Process ◽  
Parent Material ◽  
High Temperature Alloys ◽  
Wide Gap ◽  
Mechanical Cleaning ◽  
Repair Techniques

An advanced powder metallurgy repair process called Liburdi Powder Metallurgy (LPM) has been developed for the repair, overlay or joining of nickel and cobalt-based high-temperature alloys. This process involves mechanical cleaning, followed by the application and consolidation of a filler metal powder, which has substantially the same composition as the base metal, and produces joints with mechanical properties similar to those of the parent material. While previously activated braze or “wide-gap” repair processes have been limited to clearances of approximately 1 mm, the LPM technique has the ability to bridge larger gaps of over 5 mm. In addition, the LPM joints contain significantly lower concentrations of melting point depressants such as silicon and boron than conventional wide-gap repair techniques and exhibit superior microstructural features. The characteristics and typical applications of the LPM process for blade and vane repairs are highlighted and the results of laboratory and engine tests are discussed.

Effect of Ruthenium, Rhenium and Yttria Additions on the Microstructure of Wide Gap Brazing of IN738

2007 ◽  
Author(s):  
Xiao Huang ◽  
Scott Yandt ◽  
Doug Nagy ◽  
Matthew Yao
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Life Cycle Cost ◽  
Filler Metal ◽  
Braze Alloy ◽  
Cost Effective ◽  
Brazed Joints ◽  
Brazed Joint ◽  
Wide Gap ◽  
Boride Phases

Modern gas and steam turbine components are subject to severe thermomechanical loads and extremely high temperature in order to provide increased performance and efficiency. Most high temperature turbine components are made of superalloys specifically developed for high temperature and high mechanical stress applications but at considerable cost. Defects may occur during manufacturing of superalloy castings as well as after service. Repair of these components, rather than replacement, helps to reduce the life cycle cost. Wide gap brazing is a cost effective and reliable means to repair gas turbine hot section components with defect sizes exceeding 0.3 mm. With proper control of the braze alloy and brazing cycle, the repaired region has been reported to posses mechanical properties approaching that of the parent materials. In order to further improve the mechanical properties of the repaired region and to explore the possibility of employing the wide gap brazing method to repair single crystal components in the future, three alloying additions, Ruthenium (Ru), Rhenium (Re) and yttria (Y2O3), were incorporated into the braze filler metal by mechanical alloying. The microstructures of the wide gap brazed joints with Ru, Re and yttria additions were studied and compared to a braze joint with standard wide gap braze alloys of IN738 and AWS BNi-9. It has been found that two types of borides formed in all braze alloys, namely eutectic γ-Ni-rich and boride phases and discrete boride containing primarily Cr and W (or Ru). The addition of Ru to the filler metal did not seem to modify the microstructural constituents after brazing. However, Ru partitioned strongly to the discrete borides. No isolated elemental Ru region was observed. On the other hand, Re addition was found to change the occurrence and distribution of both types of borides. The eutectic boride constituent was significantly reduced and finer discrete boride particles were observed. The addition of yttria did not change the boride formation but led to the generation of more voids in the brazed joint.

Micro-Pore Structure and Mechanical Properties of High Temperature Self-Lubricating Biomimetic TiC/FeCrWMoV Cermets

2007 ◽  
Vol 546-549 ◽  
pp. 2273-2278 ◽  
Author(s):  
Yan Jun Wang ◽  
Zuo Min Liu
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Powder Metallurgy ◽  
Pore Structure ◽  
Network Structure ◽  
Sweat Gland ◽  
Solid Lubricant ◽  
Rayleigh Distribution

A new cermet sinter with sweat-gland micro-pore structure has been developed by powder metallurgy technology in vacuum. The effects of the pore-forming materials on micro-pore structure and Y2O3 additions as well mechanical properties of TiC/FeCrWMoV cermets were investigated. Some typical sweat-gland micro-pores were formed while compound additives TiH2 and CaCO3 adding into the sinter matrix. The porosity of the cermet sinters changes from 20% to 28% with the compound additives from 6% to 8%, and the micro-pores of sinters exist a regularized and interpenetrated network structure just like human’s sweat-gland one and obeying to Rayleigh Distribution. As such the sinters could be easily infiltrated with high-temperature solid lubricant. For improving the property of the ceramet sinter, the elements Y2O3 of 0.6～0.8% (vol. fraction ) was also added into the sinter matrix and its effect on the sinter has been also discussed .

Microstructure and Mechanical Properties of the Wide-Gap Region Brazed with Various Powder Mixing Ratios of Additive to Filler Metal Powders

2006 ◽  
Vol 118 ◽  
pp. 479-484 ◽  
Author(s):  
Yong Hwan Kim ◽  
S.I. Kwun
Keyword(s):  
Mechanical Properties ◽  
Metal Powder ◽  
Room Temperature ◽  
Filler Metal ◽  
Metal Powders ◽  
Powder Mixing ◽  
Factors Affecting ◽  
Mixing Ratios ◽  
Microstructure And Mechanical Properties ◽  
Wide Gap

This study investigated the microstructure and mechanical properties of the wide-gap region brazed with various powder mixing ratios of additive powder (IN738) to filler metal powder (DF4B). The wide-gap brazing process was carried out in a vacuum of 2×10-5 torr at 1230°C for 1 hr. The microstructure of the brazed region was analyzed by FESEM and AES. The wide-gap region brazed with 60wt.% IN738 additive powder and 40 wt.% DF 4B filler metal powder had a microstructure consisting of Ni solid solution + γ' and (Cr, W)2B. The fracture strength of the wide-gap region brazed with 60 wt.% IN738 additive and 40 wt.% DF 4B powder was as high as 832 MPa at room temperature. It was found that the (Cr, W)2B and pores in the brazed region are important microstructural factors affecting the mechanical properties of the wide-gap brazed region.

High-Temperture Structural Analysis on a Small-Scale PHE Prototype Considering Mechanical Properties in the Heat-Affected Zone and in the Weld Zone

2012 ◽  
Author(s):  
Kee-Nam Song ◽  
Sung-Deok Hong ◽  
Hong-Yoon Park
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Structural Analysis ◽  
Performance Test ◽  
Weld Zone ◽  
Parent Material ◽  
Small Scale ◽  
Hastelloy X ◽  
Production Of Hydrogen ◽  
Gas Loop

PHE (Process Heat Exchanger) is a key component in transferring the high temperature heat generated from a VHTR (Very High Temperature Reactor) to the chemical reaction for massive production of hydrogen. A performance test on a small-scale PHE prototype made of Hastelloy-X is currently undergoing in a small-scale gas loop at the Korea Atomic Energy Research Institute. Previous researches on the high-temperature structural analysis of the small-scale PHE prototype had been performed using parent material properties over the whole region. In this study, high-temperature elastic structural analysis considering mechanical properties in the weld zone was performed and the analysis result was compared with previous researches.

scholarly journals Wide-Gap Brazing of K417G Alloy Assisted by In Situ Precipitation of M3B2 Boride Particles

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3140 ◽  
Author(s):  
Zhun Cheng ◽  
Xiaoqiang Li ◽  
Minai Zhang ◽  
Shengguan Qu ◽  
Huiyun Li
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Room Temperature ◽  
Distribution Characteristics ◽  
Powder Metallurgy Technique ◽  
Dispersion Strengthening ◽  
Eutectic Transformation ◽  
Wide Gap ◽  
Strength And Plasticity

In this study, K417G Ni-based superalloy with a 20-mm gap was successfully bonded at 1200 °C using powder metallurgy with a powder mixture. The results indicated that the microstructure and mechanical properties of the as-bonded alloy were highly dependent on the brazing time (15–45 min), mainly due to the precipitation and distribution characteristics of M3B2 boride particles. Specifically, alloy brazed for 30 min exhibited desirable mechanical properties, such as a high tensile ultimate strength of 971 MPa and an elongation at fracture of 6.5% at room temperature, exceeding the balance value (935 MPa) of the base metal. The excellent strength and plasticity were mainly due to coherent strengthening and dispersion strengthening of the in situ spherical and equiaxed M3B2 boride particles in the γ + γ′ matrix. In addition, the disappearance of dendrites and the homogenization of the microstructure are other factors that cannot be excluded. This powder metallurgy technique, which can avoid the eutectic transformation of traditional brazing, provides a new effective method for wide-gap repair of alloy materials.

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