Post on 17-Nov-2020
Kazuya Aizawa, Stefanus Harjo, Takuro Kawasaki, Wu Gong J-PARC Center, JAEA
TAKUMI @ 20 kW (2009)
@ 120 kW (2010)
-> macroscopic strain -> phase transformation -> texture -> non-uniform strain (dislocation, etc) -> crystallite size (grain boundaries, twinning, etc)
in situ
observation
of
microstructure
as average
bulk data
-> high intensity high resolution engineering diffractometer : TAKUMI
-> measurement with wide d-range (& multi scattering vector) : TOF instrument with multi banks
-> flexible data manipulation : event data recording method
-> sample environments : e.g. high temperature loading machine
information needed :
Nanobainitic isothermal process (-> slow process)
Thermo-mech. of 2Mn-0.2C steel (-> fast process)
Other possibilities using different sample environmental (SE) devices
vacuum (or inert gas)
Incident beam
Thermodilatometry
film austenite
Element C Si Mn Cr Mo Al Co
wt% 0.79 1.51 1.98 0.98 0.24 1.06 1.58
Bainitic process -> dilatation process starting, ending volume fraction data ? In situ diffraction microstructural evolution process starting, ending
0 5000 10000 15000 20000 25000 30000
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
Bainitic ferrite
Film austenite
Bulk austenite
Volu
me fra
ctio
n
Time/s
■ Bainitic ferrite
● Film austenite
▲ Bulk austenite
300ºC
α`
γ
γ
α`:martensiteB:bainiteγ: austeniteγH:High carbon austeniteγL:Low carbon austenite2ºC/s
900ºC, 10min
Isothermal transformation at 400ºC
B+γH
+ γL
300ºC250ºC
200ºC
300sec
-5ºC/s
Bainitic transformation starts slowly depending on the isothermal temperature (diffusion of carbon)
Bulk dilatation is relevant to volume fraction of bainitic ferrite
High carbon content film austenite is also formed during bainitic transformation
Gauge size: Ø7mm x L7mm RT
900ºC, 600s
+10ºC/s
-2ºC/s
700ºC, ε = 0.15, 600s
-0.2ºC/s 620ºC, ε = 0.15, 120s
-0.2ºC/s
austenite
fcc
gamma
ferrite
bcc
alpha
austenite
fcc
gamma
ferrite
bcc
alpha
austenite
fcc
gamma
ferrite
bcc
alpha
10 s sliced diffraction data (axial dir.)
0 5000 10000 15000 20000 25000 30000 350000.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0
20
40
60
80
100
120
140
300C
250C
200C
DL(μm)
Vo
lum
e fr
act
ion
Time/s
Dilatometry
austenite -> ferrite transformation was accelerated by adding hot compression at 700ºC
Hot compression
sliced every 10s (500 hist.)
austenite -> ferrite transformation was accelerated by adding hot compression at 700ºC
Hot compression
sliced every 10s (500 hist.)
austenite -> ferrite transformation was slow at 700ºC
No hot compression
sliced every 30s (150 hist.)
austenite -> ferrite transformation was slow at 700ºC
No hot compression
sliced every 30s (150 hist.)
Thermo-mech. of a martensitic steel @ 300 kW (2013)
TOF = 31840 us
time = 2029.5 s
A martensitic steel was used. Heating to 900 C, cooling to 850 C, tensile deformation up to nominal strain of ~25% & unloading at 850 C, cooling. 2D pattern for the axial direction only obtained by slicing data per 1 second. 5mm slit and 5 mm radial collimators were used.
ganma-111
ganma-200
ganma-220
ganma-311
alpha-110
alpha-200
alpha-211
New device under development by CMSI of Kyoto Univ. Tsuji, Shibata, Oishi, et al.
Thermo-mechanical Simulation System
Highest temp: 1200 C Heating/cooling rate ≤ 30C/s Deformation rate ≤ 100 mm/s Vacuum or inert gas sample
anvils
induction coil
sample chamber
servo motor
Brought-in SE
80K chamber for deformation test
~80 K < temp. < 473 K Use liquid nitrogen for cooling To be added to loading machine
Tension up to 50 kN, compression up to 30 kN
Deformation rate ≤ 100 mm/min Load, displacement or strain control
Fatigue machine
Room temperature only Dynamic 50kN, static 60 kN
Fatigue rate < 30 Hz Tension and/or compression
Load, displacement or strain controll
Ultra-low temp. loading machine
Lowest temp: 7 K Below 20 K in ~ 3 hours
Tension only (can be used for comp. with special jig) Up 50 kN
Deformation rate ≤ 100 mm/min Load, displacement or strain control
delivered on March
under commissioning ready
Delivered until March 2014 Need commissioning during JFY 2014