Simulation of chained processes: Laser Cladding, Heat Treatment and Machining

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Simulation of chained processes:
Laser Cladding, Heat Treatment and Machining
Slideshare Distribution
April 2016
L. D’Alvise, A. Majumdar
GeonX S.A.
www.geonx.com
sales@geonx.com

Virfac ® | www.geonx.com
OBJECTIVES
The present lecture aims to:
1. Apply the welding simulation methodology to additive layer manufacturing simulation
and build a first prototype
2. Demonstrate the feasibility and pertinence of manufacturing chaining simulation.
3. Perform sensitivity studies on the operating conditions and check the influence on
quality criteria in terms of residual distortions.
Process n°1
Process n°2
Process n°3
© 2012-2016 GeonX – All rights reserved

APPLICATION DESCRIPTION
Machining
Simple (for validation purposes) additive manufacturing application (laser
cladding: tube on support) followed by machining.
Additive Layer
Manufacturing
Distortions
from the T/M
process
Final part
within
geometrical
tolerances
• Large excursions of temperature
• Cycling heat load over one location
• Cycling material melting & solidification
• Large excursions of material properties

APPLICATION DESCRIPTION
Machining
A heat treatment is added to improve the manufacturing chain. Simulations
will provide a quantification of its influence on final distortions.
Stress Relief
Heat Treatment
Additive Layer
Manufacturing
Distortions
from the T/M
process
Reduction of
stresses before
machining
Distortions
from the
machining
process

WORK PLAN
MA
-
Corrective
Machining
The present study aims to setup a demonstrator of process chaining simulation.
The following questions will be addressed:
1. How far the ALM part will be from the nominal geometry ?
2. How will the SRHT change the distortions inherited from the ALM ?
3. How will the machining process influence the distortions of the final part ?
4. How will the SRHT influence the whole chain and final distortions ?
Important notice: this numerical model will be used as a simulation demonstrator
and not yet for experimental validation purposes (see perspectives).
SRHT
-
Stress Relief
Heat Treatment
ALM
-
Additive Layer
Manufacturing

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SIMULATION DESCRIPTION - ALM
Additive Layer
Manufacturing
Stage n°1: Additive Layer Manufacturing
1. Operating conditions:
 Tube on plate: ext.diam. 52.4 mm, length 25 mm, thickness 2.2 mm
 Material: Inconel 718
 Number of cladding layers: 14
 Loading speed: 13.3 mm/s
 Loading time: 172 s
 Post-ALM cooling time (on threshold 20°C): 1579 s
2. Modelling hypothesis:
 Thermo-Mechanical coupling (welding model with filler material)
 Transient analysis
 HEXAhedra elements conforming to the clad
 Automatic mesh elements’ activation according to a moving box of selection
 Heat loading: energy density applied in the activated FE elements (volume)
 Thermal properties as a function of temperature
 Mechanical properties as a function of temperature (Elasto-Plastic # Power Law)
 Distributed Multi-Processing analysis: 12 processors

SIMULATION RESULTS - ALM
ALM sequence:
 Same starting point for each layer
 Same loading direction for all layers

SIMULATION RESULTS - ALM
Residual distortions (after ALM + cooling):
 Comparison against the nominal geometry
 Cross section parallel to the ALM start
 Deflection at the top of the tube: -0.637 mm
 Maximum deflection (radial): -0.755 mm
δtop = -0.637 mm
δmax = -0.755 mm
Cross section

SENSITIVITY STUDIES - ALM
Alternative layer sequences:
Influence on residual distortions
Configuration T2:
 Same start for each layer
 Alternating loading direction
from one layer to the next
Configuration T3:
 90° shift start for each layer
 Same loading direction for
all layers
Configuration T4:
 90° shift start for each layer
 Alternating loading direction
from one layer to the next
i
i+1
i
i+1

i
i+1Cross section
δtop = -0.475 mm
δmax = -0.594 mm
Reference (configuration T1):
δtop = -0.637 mm
δmax = -0.751 mm
Configuration T2:

δtop = -0.66 mm
δmax = -0.747 mm
Cross section
δtop = -0.637 mm
δmax = -0.751 mm
Configuration T3:

δtop = -0.577 mm
δmax = -0.700 mm
Cross section
i
i+1
δtop = -0.637 mm
δmax = -0.751 mm
Configuration T4:

MODELLING DESCRIPTION
Additive Layer
Manufacturing
Stage n°2: Stress Relief Heat Treatment
 Tube on plate: deformed shape from the ALM process
 Geometry: Configuration T2 selected
 Material: Inconel 718
 Stress relief process: Annealing [*ASM International]
 Ramp Up on threshold: [20, 950] °C
 Annealing Temperature: 950 °C
 Holding time: 1 hour
 Ramp Down on threshold : [950, 20] °C
 Deformed mesh from the upstream analysis (ALM)
 Residual Stresses mapped from the upstream process (ALM)
 Thermo-Mechanical coupling (staggered)
 Transient analysis
 Shared Memory Processing analysis: 12 processors
Stress Relief
Heat Treatment
Mesh’

SIMULATION RESULTS - SRHT
Effect of heat treatment on distortions:
 Expansion of the tube under the effect temperature increase
 During cooling down, shrinkage of the workpiece
 The plate constraints the tube shrinkage and stress increases at the border
Magnify: 10x

SIMULATION RESULTS - SRHT
Residual distortions (after heat treatment):
 Comparison against the nominal geometry
 Cross section parallel to the ALM start
 Deflection at the top of tube: from -0.475 to -0.367 mm
 Maximum deflection (radial): from -0.594 to -0.441 mm
 Smaller distortions after heat treatment
δtop = 0.367 mm
δmax = 0.441 mm
i
i+1Cross section

MODELLING DESCRIPTION
Additive Layer
Manufacturing
Stage n°3: Machining
 Tube on plate: deformed from the Heat Treatment process
 Geometry: Configuration T2 selected
 Machining process: surface finish (cylindrical shape)
 Thickness of removed material: 0.2, 0.4, 0.6 mm
 Objective: flat surfaces
 Deformed mesh from the upstream analysis (ALM + SRHT)
 Residual Stresses mapped from the upstream process (ALM + SRHT)
 Mechanical analysis based on XFEM
 Cutting passes represented by Level-Sets
 Two setups will be considered:
 Without the heat treatment
 With the heat treatment
Stress Relief
Heat Treatment
Mesh’
Machining
Mesh’’

SIMULATION RESULTS - MA
Machining thickness sensitivity:
 Effect of machining on residual distortions
 Without Stress Relief Heat Treatment
 The 0.6 mm thickness leads to flat external surfaces
Thickness
(mm)
Rtop
(mm)
Rmin
(mm)
|Δ|
(mm)
0.2 25.882 25.775 0,107
0.4 25.798 25.776 0.022
0.6 25.592 25.599 0.007
i
i+1Cross section
Additive Layer
Manufacturing
Machining
Flat surface

SENSITIVITY STUDIES - MA
Machining thickness sensitivity:
 Effect of machining on residual distortions
 With Stress Relief Heat Treatment
 The 0.4 mm thickness leads to flat external surfaces
Additive Layer
Manufacturing
Stress Relief
Heat Treatment
Machining
HT Thickness
(mm)
Rtop
(mm)
Rmin
(mm)
|Δ|
(mm)
Yes 0.2 25.89 25.850 0.040
No 0.2 25.88 25.775 0,107
i
i+1Cross section

SENSITIVITY STUDIES - MA
Evaluation of residual stresses:
 Before machining (after HT)
 After machining
 Deformation is magnified 10 times
 Prediction of residual distortions
Before machining (after HT) After machining

FURTHER DETAILS
Please contact us to know more about
VIRFAC features
Dr. Laurent D’Alvise
Mail: sales@geonx.com
Skype: geonx_
Visit: www.geonx.com
Follow us on Twitter: geonx_
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Simulation of chained processes: Laser Cladding, Heat Treatment and Machining

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