Evolution of microstructure and microtexture during hot deformation in an advanced P/M nickel base superalloy

2018 ◽  
Vol 146 ◽  
pp. 217-236 ◽  
Author(s):  
S.S. Satheesh Kumar ◽  
T. Raghu ◽  
Pinaki P. Bhattacharjee ◽  
G. Appa Rao ◽  
Utpal Borah
Keyword(s):  
Hot Deformation ◽  
Nickel Base Superalloy ◽  
Nickel Base ◽  
Evolution Of Microstructure ◽  
Base Superalloy ◽  
Microstructure And Microtexture

scholarly journals Grain Refinement of a Powder Nickel-Base Superalloy Using Hot Deformation and Slow-Cooling

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1978 ◽  
Author(s):  
Xianqiang Fan ◽  
Zhipeng Guo ◽  
Xiaofeng Wang ◽  
Jie Yang ◽  
Jinwen Zou
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Hot Deformation ◽  
Nickel Base Superalloy ◽  
Polycrystalline Nickel ◽  
Slow Cooling ◽  
Homogeneous Microstructure ◽  
Average Grain Size ◽  
Nickel Base ◽  
Base Superalloy

A pre-hot-deformation process was applied for a polycrystalline nickel-base superalloy to active deformation twins and dislocations, and subsequent slow cooling treatment was used to achieve grain refinement and microstructure homogenization. The microstructural evolution of the alloy was investigated, and the corresponding underlying mechanism was discussed. It was found that twinning mainly occurred in large grains during pre-hot-deformation owing to the stress concentration surrounding the large grains. High density dislocations were found in large grains, and the dislocation density increased approaching the grain boundary. The average grain size was refined from 30 μm to 13 μm after slow cooling with a standard deviation of grain size decreasing from 10.8 to 2.8, indicating a homogeneous microstructure. The grain refinement and microstructure homogenization during cooling process could be achieved via (i) static recrystallization (SRX), (ii) interaction of twin tips and γ’ precipitates, and (iii) grain coarsening hindered by γ’ precipitates in grain boundaries.

Constitutive modeling for predicting peak stress characteristics during hot deformation of hot isostatically processed nickel-base superalloy

2015 ◽  
Vol 50 (19) ◽  
pp. 6444-6456 ◽  
Author(s):  
S. S. Satheesh Kumar ◽  
T. Raghu ◽  
Pinaki P. Bhattacharjee ◽  
G. Appa Rao ◽  
Utpal Borah
Keyword(s):  
Constitutive Modeling ◽  
Hot Deformation ◽  
Peak Stress ◽  
Nickel Base Superalloy ◽  
Nickel Base ◽  
Base Superalloy

Hot Deformation Behavior and Processing Map of a Nickel-Base Superalloy GH4169

2013 ◽  
Vol 834-836 ◽  
pp. 432-436 ◽  
Author(s):  
Fu Wei Kang ◽  
Xue Min Zhang ◽  
Jian Fei Sun ◽  
Jun Ling Zhao
Keyword(s):  
Strain Rate ◽  
Power Dissipation ◽  
Hot Deformation ◽  
True Strain ◽  
Stability Domain ◽  
Nickel Base Superalloy ◽  
Peak Efficiency ◽  
True Strain Rate ◽  
Nickel Base ◽  
Base Superalloy

The hot deformation behaviors of the nickel-base superalloy GH4169 have been studied by isothermal constant true strain rate compression testing at 950°C-1150°C, 0.01s-1-10s-1and the height reduction 50%. The processing maps of GH4169 alloy have been constructed at different strains on the basis of testing data using a dynamic materials modeling. The maps exhibited two domains: the first at 950°C - 1100°C and strain rate higher than 0.1s-1, with a peak efficiency of power dissipation of 0.1, and the second at 950°C-1100°C and strain rate lower than 1s-1, with a peak efficiency of power dissipation of 0.4 and the strain rate of 0.01s-1. On the basis of microstructure observations, the first exhibits adiabatic shear bands, which called instability domain, the second represents fine recrystallized grain structures, which called stability domain. The optimal hot-working parameters are at 1050°C, 0.01s-1.

scholarly journals Hot Deformation Behaviors and Microstructure Evolution in a New PM Nickel-Base Superalloy

2011 ◽  
Vol 278 ◽  
pp. 411-416 ◽  
Author(s):  
Gao Feng Tian ◽  
Jin Wen Zou ◽  
Yu Wang ◽  
Wu Xiang Wang
Keyword(s):  
Activation Energy ◽  
Hot Deformation ◽  
Nickel Base Superalloy ◽  
Compression Tests ◽  
Working Process ◽  
Test Conditions ◽  
Deformation Behaviors ◽  
Nickel Base ◽  
Activation Energy Of Deformation ◽  
Base Superalloy

The hot deformation behaviors and the effect of flow stress on the microstructure were investigated for the as-HIPed and as-extruded materials in a new PM nickel-base superalloy. Under most test conditions, the as-extruded material exhibits superplastic flow because of grain growth corresponding to work hardening during deformation process, activation energy for deformation of which is 211 kJ/mol. However, activation energy of deformation for the as-HIPed material is 717 kJ/mol, because grain size is refined due to dynamic recrystallization, the reason being considered to be associated with the initial microstructure before the deformation. Based on the results of compression tests, two constitutive equations for the two materials were established using the mathematical regression; these will provide the valuable helps for predicting and controlling the deformed microstructure as well as optimizing hot-working process.

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