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A. Profiling&following control algorithm processing
Assumptions the three directions on the deformation in
the processing are GX 、 Gy 、 Gz, then integrated
deformation μ using the following equation :
μ = G
X
+ GY
+ GZ
The integrated deformation should be controlled during
processing, namely: μmin
≤ μ ≤ μmax
.
Among them, μ
min
is to allow deformation of the
smallest integrated to ensure the machining tool is not
detached from the workpiece surface; μmax
is the
maximum allowed amount of integrated deformation to
ensure that processing does not occur when the knife had
cut phenomenon. Therefore, controlling the μ volume
between μ
min
and μ
max
the comprehensive changes in
deformation, which range from changes in the accuracy
of the machine itself and processing of allowable error
determined.
Movement rate set V, you can press the following
formula to allocate X axis and Y-axis speed:
If: 0 < μ < 2μ
xy
Then :
V
oxy
V
μ
xy
n
= − ( 1−
)
μoxy
Δμ
= V
μ
2 2
Vm = ± V −V n
If : μxy
> 2μoxy
Then : V
n
= V , Vm
= 0
Access to the value of Vn
and V
m
, it is easy solved
Vx
and V
y
.
B. Key Technical Processes
Control of technical processes is critical. Normally steel
0Cr18Ni10Ti is with good behaviors at ambient and
lower temperatures in tenacity, plasticity, solderability,
corrosion-resistance and magnetic neutrality. However, if
it is produced through improperly controlled process, the
steel may occur with intergranular corrosion which
lowers the material’s strength and plasticity. This is quite
dangerous. Besides, 0Cr18Ni10Ti is a material of poorer
performance in machining, which means difficulties in
stamping and machining of the coupling disks. Therefore,
in the production the key processes should include the
following.
(1) Strict control over the chemical compositions,
especially the percentages of chromium, nickel and
titanium elements, is critical to prevention from
intergranular corrosion, as content of the alloy elements is
extremely vital to avoidance of the corrosion.
(2) Forging may be applied to pieces which are of proper
chemical compositions but with large grains, nonuniform
microstructure or high ferrite content in rough strip
distribution. By this process, the material may be turned
into one with uniform microstructure, fine grain, lowered
ferritic content and better distribution, thus noticeably
XY
XY
improved in its performance against boiling nitric acid
intergranular corrosion.
(3) For better comprehensive performances and
corrosion-resistance of the material, it is necessary to
apply solution heat treatment and stabilization treatment.
(4) Disk design should be based on analyses and
confirmation that it is stable. If the disk was designed
unstable, then adjustments should be made onto structure
and number of disks.
(5) Multiple-stage stamping process may best be applied
instead of one-off process, as 0Cr18Ni10Ti is of poor
performance in stamping. Stamped disk which needs
finishing can be machined on a lathe.
(6) Deformation of product should be monitored and
restrained during the processing of disks.
C. Solution Heat Treatment
This process is to dissolve carbide into austenite and to
homogenize the latter. The technique is undertaken as
follows: the material is heated to a temperature between
920 and 1150 ℃ ,then chilled to ambient temperature.
Carbon element in the material is made supersaturated
and the carbide phase completely or substantially
dissolves. Carbon is made dissolved into austenite as
prevention from its combination with chromium into high
chromium carbide, in aim to strengthen the solid solution,
enhance the material in tenacity and corrosion-resistance,
eliminate its stress and soften it, as well as prepare it for
further stabilization treatment.
It is noted that over heat in solution treatment will
increase the size of grains in austenite. When volume is
certain, a coarser grain will have less intergranular area.
And under given sensitization treatment conditions the
precipitation of carbide is a relative fixed value. Thereby
a coarser grain will have more carbide precipitation per
unit area, which brings heavier intergranular chromium
depletion, thus leading to higher intergranular corrosion
sensitivity.
D. Stabilization Treatment
Stabilization treatment is undertaken after a process of
solution heat treatment, and for adequate effect, a proper
one.The technique is as follows: The material is heattreated
between 850 and 930 ℃ , heat-maintained, and
then cooled by air. By then chromic carbide dissolves
completely, while titanic carbide incompletely. The latter
precipitates in the cooling course and prevent the carbon
from integrating chromic carbide, thus effectively
avoiding intergranular corrosion and ultimately
improving the intergranular corrosion-resistance of
0Cr18Ni10Ti. When the stabilization treatment is
completed, the subsequent cooling procedure, whether it
is by air or by water, will exert roughly same effect on the
material in respect of intergranular corrosion resistance.
E. Machining
0Cr18Ni10Ti is a material hard to be machined. It is of
high tenacity, low heat conductivity, which is only a half
or even one third that of common steels. Hardening and
deformation occur when the material is cold machined at
ambient temperature, which may turn material phase into
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