Post on 22-Jan-2018
transcript
Numerical simulation to predict the final
shape of PM HIP components
IWM / IAPK Institute, RWTH Aachen University
Augustinerbach 4, 52062 Aachen Germany
Chung Van Nguyen
Email: c.nguyenvan@iwm.rwth-aachen.de
nvchungdhgt@yahoo.com
Phone: +49 241 80 96291
Mobile: +49 176 82106600
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Content
1 Introduction
2 Densification models
3 Implementation
4 Simulation results
5 Anisotropic shrinkage of PM-HIP components
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Introduction
The powder HIP production processes
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Courtesy of KEG GmbH
Anisotropic shrinkage
This problem leads to higher costs for post
processing and longer delivery time.
In order to improve technically and make it
cost efficient, NNS HIP parts must be
produced from the first shot with the
minimal geometrical allowances.
Thus, the main motivation is to create a
HIP simulation tool to replace the βtrial and
errorβ methodology.Courtesy of IWM
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Content
1 Introduction
2 Densification models
3 Implementation
4 Simulation results
5 Anisotropic shrinkage of PM-HIP components
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Simulation approach
constitutive equations
ν = νππ + νππππ + νπ‘β
νππππ = νππ
+ νππ
Modified from Von Mises yield condition
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dνπππ
= dΞ»πf1πΟππ
dΞ» =
ππ1ππππ
β πͺππππππ dνππ
ππ1ππππ
β πͺππππππ ππ1
ππππ+
ππ1ππ
β πππ1ππππ
πΏππ βππ1ππ
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ππ1ππππ
βππ1ππππ
1 2
The plastic deformation calculation bases on the consistency condition, associated flow rule
and the mass conservation principle.
πππ =πf1πΟππ
ππ1
ππ=
πβππβ1 π½2β1
3βπβππβ1 πΌ1
2
2πππ1 1 2 β β β π β ππβ1 β π0 β π β ππβ1)
ππ1ππ
= β β β ππ ,= ββ1 β ππ
Constitutive equation:
plasticity model
π1 πππ , π, π = πππ1 π) β π1 π, π β ππ¦ π = 0 1
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νππππ = νππ = νππ1 + νππ2
νππππ = νππ
ππ2 = exp βπ
π π)πππ2
ππβ1 3π π
2πππ + π π πΌ1πΏππ
νππππ = νππ
ππ2 + νππππ2
= ex p βπ
π π)πππ2
ππβ11 + π β
1
ex p πνππππ
ππβ13π π
2πππ + π π πΌ1πΏππ
Constitutive equation:
viscoplasticity model
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Content
1 Introduction
2 Densification models
3 Implementation
4 Simulation results
5 Anisotropic shrinkage of PM-HIP components
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Implementation in UMAT Subroutine
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Different material models
Table 1: Different constitutive equation used for HIP simulation
Modelβs name Characteristic
Plastic Elastoplastic νππππππ = νππ
ππ
Viscoplastic Elastoviscoplastic νππππππ = νππ
ππ2
Combined model No.1 Elasto-plasto-viscoplastic νππππππ = νππ
ππ+ νππ
ππ = νππππ
+ νππππ2
Combined model No.2 Elasto-plasto-viscoplastic νππππππ = νππ
ππ+ νππ
ππ = νππππ
+ νππππ1 + νππ
ππ2
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Content
1 Introduction
2 Densification models
3 Implementation
4 Simulation results
5 Anisotropic shrinkage of PM-HIP components
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Simulation results of test capsules
Combined models give the best shape prediction with the error below 1,5%
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Content
1 Introduction
2 Densification models
3 Implementation
4 Simulation results
5 Anisotropic shrinkage of PM-HIP components
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Shape and size
Thickness, material properties
Number of weldlines, location
of welded joints
Inhomogeneous powder
distribution
Powder particle size, size
distribution can be different
Temperature, pressure
Temperature gradient
Capsule Powder prior to HIP HIP cycle
PM HIP Production process
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With a homogeneous initial powder distribution with an inhomogeneous initial powder distribution
Influence of capsule thickness
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Influence of initial
powder distribution
Relative density distribution was determined from experiment based on Image Analysis
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Influence of initial powder
distribution
Homogeneous initial powder distribution Powder distribution from experiment
Bending due to the influence of inhomogeneous powder distribution
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Influence of powder particle size
distribution
Table 5-4: Powder particle size fraction of three used powders
Fraction F1 F2 F3 F4 F5 F6
Micron >250 250-212 212-125 125-100 45-100 <45
Powder (P1) 17 16 15 10 28 14
Powder (P2) 17 16 15 10 28 0
Powder (P3) 50 0 20 5 10 15
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Influence of powder particle size
distribution
Influence of different powder distribution distribution
Final shape of capsules which used different powder fractions as shown in the previous slide
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Homogeneous
Powder dis.
Powder dis.
Taken from IA
Capsule No.1 Comparision of
the final shape
Influence of temperature
gradient
Bending due to the influence of temperature gradient
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Optimize capsuleβs shape and size
Thank you very much for your attention
Nguyen Van Chung
IAPK β Institut fΓΌr Anwendungstechnik Pulvermetallurgie und Keramik
an der RWTH Aachen e.V.
Augustinerbach 4
52062 Aachen
www.iapk.rwth-aachen.de