lÖt 2013 aachen (2013-06-20) – dr. s. piegert , i...
Post on 16-Oct-2020
6 Views
Preview:
TRANSCRIPT
Unrestricted © Siemens AG 2013 All rights reserved. http://siemens.com/energy/power-generation/gas-turbines Technology Classification: ECCN: EAR99 AL: N US-Content: NoThis document is subject to the U.S., Canadian, EU/German and/or other national export regulations. Diversion contrary to National law may be prohibited.
E F PR GT EN MT 2 4
Characterisation and Optimisation of Braze Joints – Simulation and Experiment
LÖT 2013 Aachen (2013-06-20) – Dr. S. Piegert, I. Reinkensmeier
Unrestricted © Siemens AG 2013 All rights reserved.Technology Classification: ECCN: EAR99 AL: N US-Content: NoThis document is subject to US Export Administration Regulations, EU Dual-Use Regulations, and or other foreign national export regulations. Diversion contrary to law is prohibited."
Piegert / E F PR GT EN MT 2 42013-06-20Page 2
Motivation
Combustion Chamber
24 Hybrid Burners
Results of former attempt• heat treatment cycle
• 1100 °C/10 min + 1000 °C/4 h• static properties
• Ni 610 Rm = 310 MPa• Ni 620 Rm = 285 MPa• Ni 650 Rm = 230 MPa
• thermocyclic tests: failure after 12 cycles (RT – 400 °C)
cracked joint
Unrestricted © Siemens AG 2013 All rights reserved.Technology Classification: ECCN: EAR99 AL: N US-Content: NoThis document is subject to US Export Administration Regulations, EU Dual-Use Regulations, and or other foreign national export regulations. Diversion contrary to law is prohibited."
Piegert / E F PR GT EN MT 2 42013-06-20Page 3
Outline
• introduction
• boundary conditions
• diffusion brazing
• methods
• simulation and experiment
• design of experiment
• process robustness
• diffusion profiles
• conclusions
Page 3
Unrestricted © Siemens AG 2013 All rights reserved.Technology Classification: ECCN: EAR99 AL: N US-Content: NoThis document is subject to US Export Administration Regulations, EU Dual-Use Regulations, and or other foreign national export regulations. Diversion contrary to law is prohibited."
Piegert / E F PR GT EN MT 2 42013-06-20Page 4
Boundary Conditions• temperatures up to 500 °C• purging cycles
• water• 20 °C
• hot and contaminated atmosphere
• component life 100,000 h
Loads• fatigue
• high thermally induced strains
• 5000 cycles• corrosion• oxidation
Boundary Conditions
• temperatures up to 500 °C• purging cycles• oxidative and corrosive
environment• component life 100,000 h
Materials• substrate 16Mo3 (1.5415)
• low alloyed• heat resistant
• braze alloy Ni660• Ni-19Cr-7.3Si-1.5B• 38 µm thick
• subsequent heat treatment after brazing (aluminising)
Technological Environment
Page 4
weld design
braze design
burner hub
temperature distribution
during purging
Unrestricted © Siemens AG 2013 All rights reserved.Technology Classification: ECCN: EAR99 AL: N US-Content: NoThis document is subject to US Export Administration Regulations, EU Dual-Use Regulations, and or other foreign national export regulations. Diversion contrary to law is prohibited."
Piegert / E F PR GT EN MT 2 42013-06-20Page 5
Diffusion Brazing
Characteristics
• diffusion driven process• isothermal solidification
• microstructure comparable to base alloy no brittle phases
• structural joining• extended solidification times for wide
gaps• w0 = 300 µm tiso ≈ 50 h
1 2 widening2 maximum joint width, wmax2 4 isothermal solidification4 solidified joint, tiso5 homogenisation of solid
⎟⎠⎞
⎜⎝⎛
RTQwtiso exp~ 2
0
sche
me
of is
othe
rmal
sol
idifi
catio
n
Unrestricted © Siemens AG 2013 All rights reserved.Technology Classification: ECCN: EAR99 AL: N US-Content: NoThis document is subject to US Export Administration Regulations, EU Dual-Use Regulations, and or other foreign national export regulations. Diversion contrary to law is prohibited."
Piegert / E F PR GT EN MT 2 42013-06-20Page 6
Simulation and Experimental Methods
Experiments• determination of brazing parameters
• braze material• process window within tB -TB space via
full factorial 22 DoE with centre point• metallographical investigation• measurement of element distribution• process robustness with respect to joint width• mechanical testing
Simulation• calculation of phase diagrams
• Thermo-Calc Vers. S• TTNi7, TCFe7
• simulation of brazing process and subsequent heat treatment
• DICTRA 26• TTNi7 with MobNi1• moving boundary problem
½ w0 l >> w0
L γ-Fe
linear grid
geometrical grid
T3
T2
T1
TB/ °C
√tB / s½√t1 √t2 √t3
DoE
DIC
TRA
mod
el moving interface
Unrestricted © Siemens AG 2013 All rights reserved.Technology Classification: ECCN: EAR99 AL: N US-Content: NoThis document is subject to US Export Administration Regulations, EU Dual-Use Regulations, and or other foreign national export regulations. Diversion contrary to law is prohibited."
Piegert / E F PR GT EN MT 2 42013-06-20Page 7
Optimum Brazing Temperature
• typical shape of the curve, i.e. kinetics vs. solubility of the melting point depressant
• Topt ≈1300 °C
DoE
• isothermal solidification for t2 < t < t3• lower temperatures result in longer tiso
Process Characterisation
T3
T2
T1
TB/ °C
√tB / s½
√t1 √t2 √t32000
2500
3000
3500
4000
T / °C
t iso
/ s
T 1 T 3 1300l
Unrestricted © Siemens AG 2013 All rights reserved.Technology Classification: ECCN: EAR99 AL: N US-Content: NoThis document is subject to US Export Administration Regulations, EU Dual-Use Regulations, and or other foreign national export regulations. Diversion contrary to law is prohibited."
Piegert / E F PR GT EN MT 2 42013-06-20Page 8
T3
T2
T1
TB/ °C
√tB / s½
√t1 √t2 √t3
DoE – Experimental Results
legend:• continuous and/or large needle like borides/silicides
• discontinuous needle like borides/silicides
• discontinuous blocky borides/silicides
• joint free of any brittle phases
met
allo
grap
hica
linv
estig
atio
n of
DoE
Unrestricted © Siemens AG 2013 All rights reserved.Technology Classification: ECCN: EAR99 AL: N US-Content: NoThis document is subject to US Export Administration Regulations, EU Dual-Use Regulations, and or other foreign national export regulations. Diversion contrary to law is prohibited."
Piegert / E F PR GT EN MT 2 42013-06-20Page 9
Comparison of Simulation and Experiment
5
0
5
0
5
0
5> - - - - - < 1.5
1.5 2.02.0 2.52.5 3.03.0 3.53.5 4.0
4.0
centre
T1
T2
T3te
mpe
ratu
re
√t1 √t3√t2√time
legend:1. continuous and/or
large needle like borides/silicides
2. discontinuous needle like borides/silicides
3. discontinuous blocky borides/silicides
4. joint free of any brittle phases
cont
our p
lot a
nd s
imul
ated
t iso
Unrestricted © Siemens AG 2013 All rights reserved.Technology Classification: ECCN: EAR99 AL: N US-Content: NoThis document is subject to US Export Administration Regulations, EU Dual-Use Regulations, and or other foreign national export regulations. Diversion contrary to law is prohibited."
Piegert / E F PR GT EN MT 2 42013-06-20Page 10
Simulation of joint width dependence
• brazing time: St = 2.0• joint width: Sw = 1.4
Process Robustness
Experiment
• good mechanical properties up to 60 µm• transition to braze joint failure at 80 µm
0.0E+00
1.0E-05
2.0E-05
3.0E-05
4.0E-05
5.0E-05
6.0E-05
7.0E-05
0 20 40 60 80 100sqrt(time) / s 1̂/2
w0
/ m
16Mo3 with Ni 660 DICTRA
t3
w0 = 38 µm
margin of safety brazing time
margin of safety joint width
sqrt(time) / s^1/2
calculated limit
0
5
10
15
20
25
30
0 50 100 150
joint width / µm
A5 /
% base materialfailurebraze joint failure
16Mo3 @ RTMvision min
200
250
300
350
400
450
500
550
600
0 50 100 150
joint width / µmRm
/ M
Pa
Unrestricted © Siemens AG 2013 All rights reserved.Technology Classification: ECCN: EAR99 AL: N US-Content: NoThis document is subject to US Export Administration Regulations, EU Dual-Use Regulations, and or other foreign national export regulations. Diversion contrary to law is prohibited."
Piegert / E F PR GT EN MT 2 42013-06-20Page 11
Simulation vs. Experiment
• good agreement in regard to width of diffusion zone
• absolute values via EDX questionable
Element Distribution
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
0.E+00 5.E-05 1.E-04 2.E-04 2.E-04distance / m
c /
wt.-
%
Si - t = 0 s
Si - t = tiso
Si - t = t3
Si - fully heat treatment
0
5
10
15
20
25
0.E+00 5.E-05 1.E-04 2.E-04 2.E-04distance / m
c /
wt.-
%
Cr - t = 0 s
Cr - t = tiso
Cr - t = t3
Cr - fully heat treated 0
2
4
6
8
10
12
14
0.0E+00 5.0E-05 1.0E-04 1.5E-04distance / m
c /
wt.-
%
Cr experimental
Si experimental
Cr calculated
Si calculated
Si d
istr
ibut
ion
Cr d
istr
ibut
ion
Unrestricted © Siemens AG 2013 All rights reserved.Technology Classification: ECCN: EAR99 AL: N US-Content: NoThis document is subject to US Export Administration Regulations, EU Dual-Use Regulations, and or other foreign national export regulations. Diversion contrary to law is prohibited."
Piegert / E F PR GT EN MT 2 42013-06-20Page 12
Conclusions
• systematic approach lead to significant process improvement
• isothermal solidification is crucial for mechanical properties
• simulations can assist definition of process window and CTQs such as TB , tB, and joint width
• to date simulations cannot replace experiments
Outlook
• simulation of systems with in-situ precipitation of borides and other phases
• reduced experimental effort
16M
o3-N
i 660
-16M
o3LC
F pe
rfor
man
ce
Unrestricted © Siemens AG 2013 All rights reserved.Technology Classification: ECCN: EAR99 AL: N US-Content: NoThis document is subject to US Export Administration Regulations, EU Dual-Use Regulations, and or other foreign national export regulations. Diversion contrary to law is prohibited."
Piegert / E F PR GT EN MT 2 42013-06-20Page 13
Contact page
Dr. Sebastian Piegert Group Lead E F PR GT EN MT 2 4 - Joining and Repair
Huttenstraße 12 10553 Berlin
Phone: +49 (30) 3461 1089 Mobile: +49 (162) 132 62 79
E-mail: sebastian.piegert@siemens.com
Page 13
Unrestricted © Siemens AG 2013 All rights reserved.Technology Classification: ECCN: EAR99 AL: N US-Content: NoThis document is subject to US Export Administration Regulations, EU Dual-Use Regulations, and or other foreign national export regulations. Diversion contrary to law is prohibited."
Piegert / E F PR GT EN MT 2 42013-06-20Page 14
Disclaimer
This document contains forward-looking statements and information – that is, statements related to future, not past, events. These statements may be identified either orally or in writing by words as “expects”, “anticipates”, “intends”, “plans”, “believes”, “seeks”, “estimates”, “will” or words of similar meaning. Such statements are based on our current expectations and certain assumptions, and are, therefore, subject to certain risks and uncertainties. A variety of factors, many of which are beyond Siemens’ control, affect its operations, performance, business strategy and results and could cause the actual results, performance or achievements of Siemens worldwide to be materially different from any future results, performance or achievements that may be expressed or implied by such forward-looking statements. For us, particular uncertainties arise, among others, from changes in general economic and business conditions, changes in currency exchange rates and interest rates, introduction of competing products or technologies by other companies, lack of acceptance of new products or services by customers targeted by Siemens worldwide, changes in business strategy and various other factors. More detailed information about certain of these factors is contained in Siemens’ filings with the SEC, which are available on the Siemens website, www.siemens.com and on the SEC’s website, www.sec.gov. Should one or more of these risks or uncertainties materialize, or should underlying assumptions prove incorrect, actual results may vary materially from those described in the relevant forward-looking statement as anticipated, believed, estimated, expected, intended, planned or projected. Siemens does not intend or assume any obligation to update or revise these forward-looking statements in light of developments which differ from those anticipated.
Trademarks mentioned in this document are the property of Siemens AG, it's affiliates or their respective owners.
23 September 2013Page 14 Author / E F PR GT EN MT
top related