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=Note to Readers= | =Note to Readers= | ||
Consider the following: | Consider the following: | ||
==CET(Columnar to equiaxed transition)== | |||
=Background= | =Background= | ||
'''Journals''' | '''Journals''' | ||
*TBD - additive manufacturing or a materials science welding journal | *TBD - additive manufacturing or a materials science welding journal | ||
From Wikipedia: [https://en.wikipedia.org/wiki/Recrystallization_(metallurgy)] | From Wikipedia: [https://en.wikipedia.org/wiki/Recrystallization_(metallurgy)] | ||
Line 22: | Line 14: | ||
The columnar to equiaxed transition is critical for preventing crack growth along the columnar dendrites from the root towards the center of the solidifying metal. Equiaxed grains terminate cracks, limiting the total crack length and improve the mechanical properties of the material. | The columnar to equiaxed transition is critical for preventing crack growth along the columnar dendrites from the root towards the center of the solidifying metal. Equiaxed grains terminate cracks, limiting the total crack length and improve the mechanical properties of the material. | ||
===Factors of | ===Factors of CET=== | ||
The general factors which influence the CET are | The general factors which influence the CET are | ||
*Cooling rate | *Thermal Gradient | ||
**Cooling rate | |||
**Melt size | |||
*Solidification Velocity | |||
**Nucleation rate | **Nucleation rate | ||
*Alloy composition | *Alloy composition | ||
**Constitutional Supercooling | **Grain Refiner | ||
***Constitutional Supercooling | |||
===Impact of WAAM on CET=== | |||
WAAM(Wire arc additive manufacturing) | |||
*Multi-layer process disrupts the long range order of the solidifying microstructure through re-melt fraction | |||
*Reduces the section size/melt size of the object for any given moment | |||
*turbulent and convectional flow from the welding process results in a homogeneous microstructure element distribution | |||
*Rapid solidification allows a "as solutionized" like microstructure preventing the need for a costly heat treatment. | |||
===Running Notes and Ideas=== | ===Running Notes and Ideas=== | ||
General ideas and notes regarding CET and its impact on solidifying materials | General ideas and notes regarding CET and its impact on solidifying materials | ||
*Minimize the length of the columnar region (which acts as max crack length) | |||
*Minimize the thermal gradient(to allow nucleation ahead of the columnar front) by improving resolution | |||
*Increase the solidification rate to transition to equiaxed structure sooner. | |||
===Metrics of CET=== | |||
*Dendrite size (SDAS for solidification velocity) | |||
*Hardness / conductivity (for solutionized state) | |||
*Length % of columnar region (for transition time) | |||
*Length(distance) of columnar region (for max potential crack length) | |||
=Literature Review of CET= | =Literature Review of CET= |
Revision as of 22:20, 25 August 2020
Note to Readers
Consider the following:
CET(Columnar to equiaxed transition)
Background
Journals
- TBD - additive manufacturing or a materials science welding journal
From Wikipedia: [1]
Why CET
The columnar to equiaxed transition is critical for preventing crack growth along the columnar dendrites from the root towards the center of the solidifying metal. Equiaxed grains terminate cracks, limiting the total crack length and improve the mechanical properties of the material.
Factors of CET
The general factors which influence the CET are
- Thermal Gradient
- Cooling rate
- Melt size
- Solidification Velocity
- Nucleation rate
- Alloy composition
- Grain Refiner
- Constitutional Supercooling
- Grain Refiner
Impact of WAAM on CET
WAAM(Wire arc additive manufacturing)
- Multi-layer process disrupts the long range order of the solidifying microstructure through re-melt fraction
- Reduces the section size/melt size of the object for any given moment
- turbulent and convectional flow from the welding process results in a homogeneous microstructure element distribution
- Rapid solidification allows a "as solutionized" like microstructure preventing the need for a costly heat treatment.
Running Notes and Ideas
General ideas and notes regarding CET and its impact on solidifying materials
- Minimize the length of the columnar region (which acts as max crack length)
- Minimize the thermal gradient(to allow nucleation ahead of the columnar front) by improving resolution
- Increase the solidification rate to transition to equiaxed structure sooner.
Metrics of CET
- Dendrite size (SDAS for solidification velocity)
- Hardness / conductivity (for solutionized state)
- Length % of columnar region (for transition time)
- Length(distance) of columnar region (for max potential crack length)
Literature Review of CET
- Areas of Focus:
- Microstructure impact
- Hot tear reduction
Microstructure Focus
Microstructure of Rapidly Solidified Materials
- List A
- Thing A
- List B
- Thing B
- List C