Effect of Thermomechanical Processes on Σ3 Grain Boundary Distribution in a Nickel Base Superalloy

2010 ◽  
Vol 638-642 ◽  
pp. 2333-2338
Author(s):  
Nadia Souaï ◽  
Roland E. Logé ◽  
Yvan Chastel ◽  
Nathalie Bozzolo ◽  
Vincent Maurel ◽  
...  
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Polycrystalline Materials ◽  
Nickel Base Superalloy ◽  
Grain Boundary Engineering ◽  
Thermomechanical Process ◽  
Grain Boundary Character ◽  
Nickel Base ◽  
Thermomechanical Processes ◽  
Base Superalloy

According to various studies, Grain Boundary Engineering (GBE) is likely to enhance mechanical properties of polycrystalline materials. The present investigation highlights some relationships between thermomechanical process (TMP) parameters of a commercial nickel-base superalloy PER72, supplied by Aubert & Duval (equivalent to Udimet®720™) and the resulting microstructure. The long-term goal is to develop TMPs that modify the Grain Boundary Character Distributions (GBCD) in order to improve high temperature properties. In this context, Grain Boundary Engineering (GBE) techniques are considered, thinking of replacing standard forming processes by optimised thermomechanical treatments. Mechanical testing at high temperature (compression and torsion tests) has been carried out and it is shown that multi-step treatments promote twinning. Some clues are then presented in an attempt to explain when and how twins are created.

About the possibility of grain boundary engineering via hot-working in a nickel-base superalloy

2010 ◽  
Vol 62 (11) ◽  
pp. 851-854 ◽  
Author(s):  
N. Souaï ◽  
N. Bozzolo ◽  
L. Nazé ◽  
Y. Chastel ◽  
R. Logé
Keyword(s):  
Grain Boundary ◽  
Hot Working ◽  
Nickel Base Superalloy ◽  
Grain Boundary Engineering ◽  
Nickel Base ◽  
Base Superalloy

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

Effect of Pre-Weld Heat Treatment Temperatures on TIG Welded Microstructures on Nickel Base Superalloy, GTD-111

2015 ◽  
Vol 658 ◽  
pp. 14-18
Author(s):  
Tanaporn Rojhirunsakool ◽  
Duangkwan Thongpian ◽  
Nutthita Chuankrerkkul ◽  
Panyawat Wangyao
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Heat Treatment Temperature ◽  
Treatment Temperature ◽  
Tig Welding ◽  
Nickel Base Superalloy ◽  
Nickel Base ◽  
Base Superalloy ◽  
Weld Heat

Nickel-base superalloys have been used as high temperature materials in land-base gas turbine application. When subjected to long term, high temperature service, large crack propagation was observed. Typical refurbishment method of these turbines is carried out by using TIG welding followed by post-weld standard heat treatment. However, new crack initiation is found in the heat-affected zone after TIG welding. Pre-weld heat treatment has been discovered to improves final γ + γ’ microstructure. This study focuses on the effect of pre-weld heat treatment temperature on final γ + γ’ microstructure. Seven different conditions of pre-weld heat treatment temperature were investigated. Scanning electron microscopy studies were carried out after pre-weld and post-weld heat treatments to compare the γ + γ’ microstructure and capture microcracks. The best pre-weld heat treatment temperature produces uniform distribution of finely dispersed γ’ precipitates in the γ matrix without post-weld crack.

Influence of Etchants on Phase Morphology of Casting Ni-Based Superalloy

2014 ◽  
Vol 887-888 ◽  
pp. 366-369
Author(s):  
Juan Juan Li ◽  
Shu Jun Zang ◽  
Jian Bin Zhang
Keyword(s):  
Grain Boundary ◽  
Phase Morphology ◽  
Nickel Base Superalloy ◽  
Mixed Solution ◽  
Dendrite Structure ◽  
Etching Solution ◽  
Metallic Compounds ◽  
Nickel Base ◽  
Base Superalloy

K4169 is the Nickel-base superalloy that is the most widely used in the turbine components. The article selects three kinds of etching solution to corrode, in order to achieve the purpose that studies on its morphology. Etchant1 is the mixed solution of 15mlHCl, 10mlAcetic acid, 5mlHNO3and 2drop glycerin. Etchant2 is the mixed solution of 3ml glycerin, 3mlHCl, 1ml HNO3. Etchant 3 is the mixed solution of 20mlHNO3, 60mlHCl. The results showed that we can mainly observe strengthened phase γ'' (Ni3(Ti, Al)) and matrix γ (Fe-Ni-Cr) phase with etchant1 to corrode. Using the etchant2 to corrode, we can clearly see its dendrite structure. Using the etchant3 to corrode, we can obverse its grain boundary that includes white inter-metallic compounds. We also respectively discussed the K4169 morphology when magnifications are 200times and 500times.

Evaluation of Multicomponent Nickel Base LI2 and Other Intermetallic Alloys as High Temperature Structural Materials

1986 ◽  
Vol 81 ◽  
Author(s):  
D. M. Shah ◽  
D. N. Duhl
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Single Crystals ◽  
Impact Resistance ◽  
High Strength ◽  
Structural Materials ◽  
Nickel Base Superalloy ◽  
Intermetallic Alloys ◽  
Nickel Base ◽  
Base Superalloy

AbstractMulticomponent nickel base intermetallics with the L12 structure were evaluated as high temperature structural materials. The compounds were based on the γ' composition of PWA 1480, a high strength single crystal nickel base superalloy. The best balance of properties in the compound was achieved with <111> oriented single crystals but no significant advantage could be demonstrated over the precipitation hardened superalloys. Insufficient impact resistance was a major deficiency of the L12 compounds. Other nickel base intermetallics were also evaluated but showed little advantage over superalloys.

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