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 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.

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 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.

High Temperature Strength and Stability of Oxide Dispersion Hardened Alloys

1975 ◽  
Vol 33 ◽  
pp. 174-175
Author(s):  
M.S. Grewal ◽  
S.A. Sastri ◽  
N.J. Grant
Keyword(s):  
Activation Energy ◽  
Steady State ◽  
High Temperature ◽  
High Stability ◽  
High Strength ◽  
Steady State Creep ◽  
High Temperature Strength ◽  
Oxide Dispersion ◽  
Steady State Creep Rate ◽  
Image Position

The creep behavior of oxide dispersed alloys can be described by the following equation:where ε is steady state creep rate, σ applied stress, R gas constant, T temperature in °K, Qc activation energy for creep, n stress exponent, A and n are constants.Two unusual observations in the case of O.D. alloys are that Qc and n take on values that have not been explained satisfactorily. This investigation was undertaken to explain the unusually high strength, high Qc and high stability (high value of n) in the oxide dispersed alloys.

High-Temperature Creep of Nb-Al-V Alloys

1998 ◽  
Vol 552 ◽  
Author(s):  
Tie-Sheng Rong ◽  
Mark Aindow
Keyword(s):  
Activation Energy ◽  
Steady State ◽  
High Temperature ◽  
Creep Deformation ◽  
Steady State Creep ◽  
High Temperature Creep ◽  
Creep Mechanisms ◽  
Creep Curves ◽  
Rapid Transition ◽  
A15 Phase

ABSTRACTNb-15A1-20V alloys with about 45% by volume of an A15 phase in a B2 matrix have been subjected to creep deformation at temperatures between 1000°C and 1200°C and stresses from 80 MPa to 240 MPa in vacuum. The creep curves show a rapid transition from primary to steady-state creep with a well-defined activation energy. Microstructural observations show that the creep deformation occurs mainly in the B2 matrix and is controlled by dislocation mechanisms. Samples which had been coldrolled and annealed to reduce the size of A 15 precipitates and increase the yield strength were found to have lower creep resistance than those with unrefined microstructures. The significance of these observations for the creep mechanisms is discussed.

Study on Thermal Cycling of Sn0.7Cu Solder

2013 ◽  
Vol 791-793 ◽  
pp. 362-365
Author(s):  
Li Yang ◽  
Ju Li Li ◽  
Jing Guo Ge ◽  
Meng Li ◽  
Nan Ji
Keyword(s):  
Shear Stress ◽  
Steady State ◽  
High Temperature ◽  
Thermal Cycling ◽  
Shear Strain ◽  
Maximum Shear Stress ◽  
Steady State Creep ◽  
Maximum Shear Strain ◽  
Cycle Number ◽  
State Cycle

Thermal cycling of a unit Sn0.7Cu solder was studied based on the steady-state creep constitutive equation and Matlab software. The results show that there is a steady-state cycle for the thermal cycling of unit Sn0.7Cu eutectic solder. In steady-state thermal cycling, the shear stress is increased with the increase of temperature. There is a stage of stress relaxation during high temperature. A liner relationship between maximum shear stress and maximum shear strain is observed during thermal cycling. The metastable cycle number is declined greatly with the increase of maximum shear strain.

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.

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