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 DistributionApril 2016

L. D’Alvise, A. Majumdar

GeonX S.A.

www.geonx.com

[email protected]

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 ReliefHeat Treatment


Distortions from the T/M

process

Reduction of stresses before

machining

Distortions from the

machining process



WORK PLAN

MA-

CorrectiveMachining

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-


ALM -



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SIMULATION DESCRIPTION - ALM


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



ALM sequence:

Same starting point for each layer




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


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 mmδmax = -0.751 mm

Configuration T2:



δtop = -0.66 mm

δmax = -0.747 mm

Cross section


Configuration T3:



δtop = -0.577 mm

δmax = -0.700 mm

Cross section

i

i+1


Configuration T4:


MODELLING DESCRIPTION


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


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 treatmentδtop = 0.367 mm

δmax = 0.441 mm

i

i+1Cross section


MODELLING DESCRIPTION


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


Mesh’

MachiningMesh’’


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


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


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

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Dr. Laurent D’Alvise

Mail: [email protected]

Skype: geonx_

Visit: www.geonx.com

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Engineering

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