Microstructure and Creep Behavior of a Directional Solidification Nickel-based Superalloy

2015 ◽  
Vol 34 (4) ◽  
Author(s):  
Ning Tian ◽  
Sugui Tian ◽  
Huichen Yu ◽  
Ying Li ◽  
Xianlin Meng
Keyword(s):  
Directional Solidification ◽  
Creep Behavior ◽  
Creep Property ◽  
Creep Damage ◽  
Stress Axis ◽  
Nickel Based Superalloy ◽  
Microstructure Observation ◽  
Micro Cracks ◽  
Initiation And Propagation ◽  
Property Measurement

AbstractBy means of creep property measurement and microstructure observation, an investigation has been made into microstructure and creep behavior of a directional solidification Ni-based superalloy at high temperatures. Results show that after full heat treatment, small cuboidal γ′ precipitates distribute in the dendrite regions, while coarser ones distribute in the inter-dendrite regions. In the primary stage of creep, the γ′ phase in alloy is transformed into the rafted structure along the direction vertical to stress axis, and then the creep of alloy enters the steady state stage. And dislocations slipping in the g matrix and climbing over the rafted γ′ phase are thought to be the deformation mechanism of the alloy during steady creep stage. At the latter stage of creep, the alternate slipping of dislocations may shear and twist the rafted γ′/γ phases, which promotes the initiation and propagation of the micro-cracks along the boundaries near the coarser rafted γ′ phase. And the bigger probability of the creep damage occurs in the grain boundaries along 45° angles relative to the stress axis due to them bearing relatively bigger shearing stress.

Creep Behavior of a Re-Free Nickel-Based Single Crystal Superalloy at High Temperature

2014 ◽  
Vol 788 ◽  
pp. 466-472 ◽  
Author(s):  
Shuang Liang ◽  
Su Gui Tian ◽  
Zhong Ge Guo ◽  
Yong Chao Xue ◽  
De Long Shu
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Creep Behavior ◽  
Creep Property ◽  
Stress Axis ◽  
Microstructure Observation ◽  
Initiation And Propagation ◽  
Property Measurement ◽  
Testing Condition ◽  
Base Superalloy

The creep behavior of a Re-free single crystal Ni-base superalloy at high temperature has been investigated by means of creep property measurement and microstructure observation. The experimental results show that the creep life of the alloy under the testing condition of 1040 oC/137 MPa was measured to be 556h. In the primary stage of creep, the deformation mechanism of the alloy is dislocations slipping within the γ matrix, and the γ′ phase in the alloy is transformed into the rafted structure along the direction vertical to the stress axis. In the latter stage of creep, the alternate activation of the main/secondary slipping dislocations may twist the rafted γ′ phase to promote the initiation and propagation of the cracks along the interfaces of γ′/γ phases up to the creep fracture. And the various configurations of the rafted γ′ phase appeared in the different regions of the sample, thereinto, the coarsening and twisting of the rafted γ′ phase in the regions near the fracture may be attributed to the bigger plastic deformation.

Microstructure and Creep Property of DZ125 Nickel-Based Superalloy

2013 ◽  
Vol 747-748 ◽  
pp. 697-702 ◽  
Author(s):  
Su Gui Tian ◽  
Xian Lin Meng ◽  
Ning Tian ◽  
Hui Chen Yu
Keyword(s):  
Activation Energy ◽  
Steady State ◽  
High Temperature ◽  
Deformation Mechanism ◽  
Creep Property ◽  
Steady State Creep ◽  
Nickel Based Superalloy ◽  
Microstructure Observation ◽  
Initiation And Propagation ◽  
Property Measurement

By means of creep property measurement and microstructure observation, an investigation has been made into the creep behaviors of DZ125 superalloy at high temperature and low stress. Results showed that the superalloy under the applied stress of 137MPa at 1293 K displayed a better creep resistance, and the apparent creep activation energy of the alloy during steady state creep was measured to be Q = 325.57 kJ/mol. The various microstructures were displayed in different regions of the sample, thereinto, the rafted γ phase was uniformly distributed in the regions far away from the fracture, but the twisted and coarser rafted γ phase appeared in the region near the fracture. The deformation mechanism of the alloy during steady state creep was the dislocations climbing over the rafted γ phase. In the later stage of creep, significant amount of dislocations shearing into the rafted γ-phase promoted the initiation and propagation of the cracks along the boundaries up to the occurrence of fracture, which was though to the fracture mechanism of the alloy during creep.

Microstructure and Creep Property of Isothermal Forging GH4169G Superalloy

2014 ◽  
Vol 33 (5) ◽  
pp. 447-451
Author(s):  
Zhenrong Li ◽  
Chunlei Ma ◽  
Sugui Tian ◽  
Liqing Chen ◽  
Xianghua Liu
Keyword(s):  
Creep Property ◽  
Induce Stress ◽  
Experimental Conditions ◽  
Microstructure Observation ◽  
Initiation And Propagation ◽  
Pile Up ◽  
Direct Aging ◽  
The Matrix ◽  
Deformation Features ◽  
Property Measurement

AbstractBy means of direct aging, microstructure observation and creep property measurement, the microstructure and creep behaviors of GH4169G superalloy are investigated. Results show that, after direct aging, the grain size is inhomogeneous in the alloy, and some δ precipitates discontinuously distribute in the grain and along the boundaries, which may improve the bonding strength of the boundaries. Under the experimental conditions, the creep activation energy of the alloy during steady-state creep are calculated to be Q = 594.7 kJ/mol. During creep, the deformation features of the alloy are twinning deformation and dislocations slipping in the matrix. As creep goes on, deformed dislocations pile up near the boundary regions to induce stress concentration for promoting the initiation and propagation of cracks along boundaries.

Creep Behavior of a 4.5% Re Nickel-Base Single Crystal Superalloy at High Temperature

2015 ◽  
Vol 750 ◽  
pp. 139-144 ◽  
Author(s):  
De Long Shu ◽  
Su Gui Tian ◽  
Xin Ding ◽  
Jing Wu ◽  
Qiu Yang Li ◽  
...  
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Single Crystal ◽  
Deformation Mechanism ◽  
Creep Property ◽  
Single Crystal Superalloy ◽  
Micro Cracks ◽  
Initiation And Propagation ◽  
Temperature Ranges ◽  
Nickel Base

By means of heat treatment and creep property measurement, an investigation has made into the creep behaviors of a containing 4.5% Re nickel-base single crystal superalloy at high temperature. Results show that the elements W, Mo and Re are enriched in the dendrite arm regions, the elements Al, Ta, Cr and Co are enriched in the inter-dendrite region, and the segregation extent of the elements may be obviously reduced by means of heat treatment at high temperature. In the temperature ranges of 1070--1100 °C, the 4.5% Re single crystal nickel-based superallloy displays a better creep resistance and longer creep life. The deformation mechanism of the alloy during steady state creep is dislocations slipping in the γ matrix and climbing over the rafted γ′ phase. In the later stage of creep, the deformation mechanism of alloy is dislocations slipping in the γ matrix, and shearing into the rafted γ′ phase, which may promote the initiation and propagation of the micro-cracks at the interfaces of γ/γ′ phases up to the occurrence of creep fracture.

Microstructure and Tensile Deformation Features of Tandem Hot Rolling GH4169 Superalloy

2014 ◽  
Vol 33 (2) ◽  
pp. 131-136
Author(s):  
Zhenrong Li ◽  
Chunlei Ma ◽  
Sugui Tian ◽  
Liqing Chen ◽  
Xianghua Liu
Keyword(s):  
Hot Rolling ◽  
Tensile Deformation ◽  
Solution Treatment ◽  
Microstructure Observation ◽  
Large Numbers ◽  
Initiation And Propagation ◽  
The Matrix ◽  
Deformation Features ◽  
Δ Phase ◽  
Property Measurement

AbstractBy means of solution treatment, microstructure observation and mechanical property measurement, the microstructure and tensile deformation features of tandem hot rolling GH4169 alloy have been investigated. Results shown that, after solution treatment and aging, large numbers of the spherical γ′ phase and the flat-ellipsoidal γ″ phase dispersedly precipitate in the matrix, and acicular or short rod-like δ-phase discontinuously distribute along grain boundaries. As the tensile temperatures increases, the tensile strength and yield strength of the alloy gradually decrease. The tensile deformation features of the alloy are that the twinning and slipping dislocations with double orientations are activated in the matrix. In the later tension, the deformed dislocations pile up near the grain boundary to induce initiation and propagation of cracks due to stress concentration.

Creep Behaviors of a Single Crystal Nickel-Based Superalloy Containing 4.2%Re

2011 ◽  
Vol 689 ◽  
pp. 276-281 ◽  
Author(s):  
Su Gui Tian ◽  
Ben Jiang Qian ◽  
Fu Shun Liang ◽  
An An Li ◽  
Xing Fu Yu
Keyword(s):  
Single Crystal ◽  
Applied Stress ◽  
Microstructure Evolution ◽  
Deformation Mechanism ◽  
Stress Axis ◽  
Steady Creep ◽  
Nickel Based Superalloy ◽  
Microstructure Observation ◽  
Creep Curves ◽  
Main Deformation

By the measurement of creep curves and microstructure observation, an investigation has been made into the creep behaviors and microstructure evolution of a single crystal nickel-based superalloy containing 4.2%Re. Results show that the superalloy displays an obvious sensibility on the applied temperatures and stresses in the range of the applied temperatures and stresses. During the initial creep, the cubical g¢ phase in the alloy is transformed into an N-type rafted structure along the direction vertical to the applied stress axis. After crept up to fracture, the rafted g¢ phase in the region near fracture is transformed into a twisted configuration. The dislocation climbing over the rafted g¢ phase is considered to be the main deformation mechanism of the alloy during the steady creep state, and dislocations shear into the rafted g¢ phase is the main deformation mechanism of the alloy in the later stage of creep.

Influence of specimen thickness on the creep behavior of a directional solidification nickel-based superalloy

Vacuum ◽  
2018 ◽  
Vol 150 ◽  
pp. 105-115 ◽  
Author(s):  
Yebing Hu ◽  
Li Zhang ◽  
Congqian Cheng ◽  
Pengtao Zhao ◽  
Tieshan Cao ◽  
...  
Keyword(s):  
Directional Solidification ◽  
Creep Behavior ◽  
Specimen Thickness ◽  
Nickel Based Superalloy

Deformation and Damage Features of a 4.5% Re Nickel-Based Single Crystal Superalloy during Creep at Medium Temperature

2014 ◽  
Vol 788 ◽  
pp. 459-465 ◽  
Author(s):  
De Long Shu ◽  
Su Gui Tian ◽  
Jing Wu ◽  
Zhong Ge Guo
Keyword(s):  
Single Crystal ◽  
Single Crystal Superalloy ◽  
Stress Axis ◽  
Fracture Mechanisms ◽  
Medium Temperature ◽  
Creep Properties ◽  
Microstructure Observation ◽  
Micro Cracks ◽  
Deformation And Fracture ◽  
Main Deformation

The deformation and damage behaviors of a 4.5% Re nickel-based single crystal superalloy during creep at medium temperature were conducted by means of creep properties measurement and microstructure observation in the present investigation. The results show that the creep life of the superalloy was measured to be 226h at 820MPa/820oC, displaying a better creep resistance. After the alloy crept up to fracture, the γ′ phase in the region near fracture was contorted and coarsened, which is attributed to the severe plastic deformation. In the latter stage of creep, the main/secondary slipping systems were alternately activated to twist the γ′ and γ phases, which promoted the initiation of the cracks along the interfaces of γ′ /γ phases. And the micro-cracks may be propagated both along the direction vertical to the stress axis and along the direction of slipping traces, which is thought to be the main deformation and fracture mechanisms of the alloy in the latter stage of the creep.

Creep Behavior of a Single Crystal Nickel-Based Superalloy Containing Re/Ru at 1100°C/137MPa

2015 ◽  
Vol 816 ◽  
pp. 551-556
Author(s):  
Su Gui Tian ◽  
Bao Shuai Wang ◽  
Xin Ding ◽  
De Long Shu ◽  
Jing Wu
Keyword(s):  
Single Crystal ◽  
Creep Behavior ◽  
Creep Resistance ◽  
Nickel Base Superalloy ◽  
Nickel Based Superalloy ◽  
Deformation Feature ◽  
Heat Treated ◽  
Initiation And Propagation ◽  
Nickel Base ◽  
Base Superalloy

Creep behavior of a heat treated single crystal nickel base superalloy containing Re/Ru under the test condition of 1100°C/137MPa high temperatures was investigated. The experimental results showed that the segregation extent of elements in the dendrite and inter-dendrite regions of single crystal superalloy decreases by heat treatment at high temperature. The creep life of the alloy at 1100°C/137MPa was measured to be 321 h displaying a better creep resistance. Wherein, significant amount of fine cubiodal γ′ particles precipitated in the γ matrix channels are considered to be the main reason of the alloy having the better creep resistance. The deformation feature of the alloy during steady state creep is dislocations slipping in the γ matrix and climbing over the rafted γ′ phase. But in the latter stage of creep, the deformation feature of the alloy is dislocations shearing into the rafted γ′ phase. As creep goes on, the main / secondary slipping dislocations in the alloy are alternately activated to result in the initiation and propagation of the cracks along the interface of the rafted γ′/γ phase up to fracture, which is thought to be the fracture mechanism of the alloy during creep.

Deformation Features of a High Mo Nickel-Based Single Crystal Superalloy during Creep at High Temperature

2019 ◽  
Vol 795 ◽  
pp. 35-42
Author(s):  
Hua Jin Yan ◽  
Su Gui Tian ◽  
Guo Qi Zhao ◽  
Shun Ke Zhang
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Single Crystal Superalloy ◽  
Stress Axis ◽  
Creep Properties ◽  
Nickel Based Superalloy ◽  
Damage And Fracture ◽  
Initiation And Propagation ◽  
Deformation Features ◽  
Fracture Features

The deformation and damage features of a high Mo single crystal Ni-based superalloy during creep at high temperature are investigated by means of measuring creep properties and observing microstructure. Results show that, compared to 4%Mo single crystal nickel-based superalloy, the 6%Mo superalloy displays a better creep resistance, and the creep life of 6%Mo single crystal superalloy at 1040°C/137MPa is measured to be 556 h. In the ranges of applied temperatures and stresses, the creep activation energy of the alloy is measured to be 484.7kJ/mol. Wherein, the deformation mechanisms of the 6%Mo superalloy during steady state creep are dislocations slipping in ϒ matrix and climbing over the rafted ϒ' phase. In the later stage of creep, the deformation mechanism of alloy is dislocations shearing into the rafted ϒ' phase, the alternate activation of dislocations slipping results in the twisted of the rafted ϒ'/ϒ phases, as the creep goes on, to promote the initiation and propagation of cracks along the interface of the twisted ϒ/ϒ' phase perpendicular to the stress axis, up to creep fracture, which is thought to be the damage and fracture features of the alloy during creep at high temperature.

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