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Деформированный чугун – эффективный заменитель

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Physical-Technical Institute of
National Academy of Sciences
Belarus, Minsk
http://www.phti.belhost.by
Е-mail: phti@tut.by
Tel/fax: (+375-17-263-76-93)
Founded 1931
Personnel370
Laboratories- 30
Activity lines:
1. New materials for
machine building
2. New technologies for thermal and deformation
processing of materials
Praha AIP 02 12 2008
1
Physical-Technical Institute of
National Academy of Sciences,
Belarus, Minsk
Praha AIP 02 12 2008
2
Physical-Technical Institute of
National Academy of Sciences,
Belarus, Minsk
Artur Pokrovsky
«Investigation and optimization
of iron deformability»
(Example of unusual action on
traditional material)
Praha AIP 02 12 2008
3
Iron, classical approach:
Excellent
casting material
Hardly deformable
Material only for non-critical items
New view on iron:
1. Deformed iron enters the class of
materials of high quality
2. Has superior properties
3. Its area of applications is wider
4
Praha AIP 02 12 2008
Iron benefits as compared to steel
1.
2.
3.
4.
Higher thermal conductivity
results in rapid heat sink
(cylinder sleeves, guide valve
sleeves)
Antifriction properties
(camshafts, crank shafts, piston
rings)
Quicker damping of vibrations
and sounds (valve pushers)
Lighter by 10% (casings,
pallets)
5
Praha AIP 02 12 2008
Drawbacks of iron:
Low mechanical properties
Casting defects degrading the properties
6
Praha AIP 02 12 2008
Traditional means of increasing
mechanical properties of iron:
Alloying
Modifying
Thermal treatment
Quality of a casting,
Casting defects:
Problems do not vanish
7
Praha AIP 02 12 2008
Advantages of deformation
processing :
3. Accuracy of
shaping
2.Increase of strength
characteristics
1.Guaranteed quality
of metal
8
Praha AIP 02 12 2008
Physical-Technical Institute of National Academy of
Sciences, Belarus, Minsk
Why we turn to deformation of iron :
•
•
•
Casting defects such as pores and cavities
are avoided
Mechanical properties are enhanced up to
the level of alloyed steel
(strength is 1200 MPa, elongation 15%)
Antifriction characteristics are increased by
a factor of 1.5
Praha AIP 02 12 2008
9
Control of graphite shape
Traditional approach:
Change of graphite shape
from branchy to compact
and spherical ones
10
Praha AIP 02 12 2008
Control of graphite
shape on deforming
And vice versa,
from spherical
shape to fibers
11
Praha AIP 02 12 2008
We tested the following classes of irons :
Gray iron
Malleable iron
Mottled iron
High-strength iron
And have found the most ADVANTAGEOUS ONES
12
Praha AIP 02 12 2008
Problems:
Temperature parameters
of deforming
Steel: 1200 – 800ОС (Δ 400ОС)
Irons : 950 – 850ОС (Δ 100ОС)
13
Praha AIP 02 12 2008
Temperature parameters
50
70
Высокопрочный
Высокопрочный
40
Н а гру з ка , у с л . е д .
О т нос ит е л ьное у д л ине ние , %
60
30
Ковкий
20
Ковкий
50
40
Серый
30
20
10
Серый
10
Половинчатый
Половинчатый
0
0
20
800
850
900
950
1000 1050
Температура испытания,
14
о
С
1100
0
1
2
3
4
5
6
7
8
Абсолютное удлинение образца, мм
Praha AIP 02 12 2008
9
10 11
Conditions of iron deforming
There are 5 groups of «know-how» :
1. Alloying diagrams
2. Preliminary thermal treatment for
improvement of deformability
3. Design of press-forging tool
4. Temperature-force parameters of
deforming
5. Finishing thermal treatment
15
Praha AIP 02 12 2008
Example of deliberate selection
of parameters for iron deforming
Part: body of drill chuck
Press forging
from a solid billet FOR ONE STROKE
16
Praha AIP 02 12 2008
Example of violating the iron
deforming conditions
Part: Cylinder of jack plunger for MAZ truck
Spoiled
product
(press-forging
temperature is
violated)
17
High-quality semifinished product
Praha AIP 02 12 2008
Finished
part
Schematic diagram of
iron deforming
1 – Iron billet heated to
high temperature
2 – Body of press tool
3 – Intermediate medium
4 - Punch
5 – Die
6 - Guide bush
18
Praha AIP 02 12 2008
Making the samples for investigations
Longitudinal samples:
Incoming
casting
billet
Transverse samples:
Press-forged
rod
19
Praha AIP 02 12 2008
Wearing weight loss after 16 thous. cycles, kg/m3 10-5
Wearing weight loss during dry friction, deformed
condition:
(Decrease by a factor of 1.5 as compared that in casting condition)
25
In order of decreasing
wear resistance:
20
GI
1. Mottled iron, (MtI)
2. High-strength iron,
(HSI)
3. Malleable iron, (MI)
4. Gray iron, (GI)
15
MtI
10
5
HSI
Casting
MI
80%-deform ation
20 0
Praha AIP 02 12 2008
Significant feature of deformation is
anisotropy of structure and properties
21
Praha AIP 02 12 2008
Anisotropy of wear during dry friction
18
Longitud. sample
The selection is made
of optimum relationships
between:
Wearing weight loss, kg/m3 10-5
16
Longitudinal
sample
Ferrite
structure
14
Transverse samp.
Deformation
parameters
Longitud. sample
Microstructures
Friction directions
12
10
Pearlite
structure
8
Transverse samp.
Transverse sample
6
0
22
60
40
20
Degree of deform ation, %
80
Praha AIP 02 12 2008
Dry Friction:
Coefficient of friction can be decreased
by a factor of 2.5
0,5
Longitudinal
Transverse
sample
sample
Coefficient of friction
0,4
Transverse samples
0,3
0,2
Longitudinal samples
0,1
0
20
40
60
Degree of deform ation, %
23
Praha AIP 02 12 2008
80
Probable factors that cause
improvement of deformed iron
characteristics:
1.
2.
3.
4.
Refinement of austenite grain
Change in pearlite morphology
Change in graphite morphology
Origination of new graphite
inclusions
24
Praha AIP 02 12 2008
1. Refinement of austenite grain
Grain number 3-4
Grain number 8-9
25
Praha AIP 02 12 2008
2. Changes in pearlite morphology
х 10000
х 10000
х 15000
26
Praha AIP 02 12 2008
3. Changes in graphite morphology
27
Praha AIP 02 12 2008
4. Formation of
new graphite
inclusions
28
Praha AIP 02 12 2008
Physical-Technical Institute of National
Academy of Sciences, Belarus, Minsk
Industrial testing of
deformed iron
Various parts have been offered but the greatest
interest has been shown in
2 lines
(that will be discussed below):
Praha AIP 02 12 2008
29
Physical-Technical Institute of National Academy of
Sciences, Belarus, Minsk
High-quality billets of piston
and sealing rings made from deformed iron
Their mechanical properties
are 2 times higher than those of
cast rings
Any failures are absent
7-fold decrease of lubricant
bleeding
No wear increase of mating part
Stable and one and the same
quality throughout the whole
height
Praha AIP 02 12 2008
30
Appreciation in Belarus and Russia
31
Praha AIP 02 12 2008
Physical-Technical Institute of National Academy of
Sciences, Belarus, Minsk
High-quality billets of gears
made from deformed iron
Strength is at the level
of alloyed steel
Noise in trucks is lower
by 3 to 4 db
Weight of gears is lower
by 9 % (the economy
for one set is 700 g)
Praha AIP 02 12 2008
32
Disadvantages of technology
High power requirements. A billet is to be heated.
Some time is required for designing, fabricating
and adjustment of press-forging tool.
Costly press tool.
Economically sound are:
Both mass production from 50 thousand pc per year
(e. g., gears for MAZ) and piece production
(e. g., piston rings «Formula-1»).
33
Praha AIP 02 12 2008
Present-day investigation
problems:
1. Technological directional thrust is
ahead of fundamental knowledge.
2. The factors that cause iron hardening
are still not completely cleared up.
3. The role played by structure factors
in hardening is ambiguous.
34
Praha AIP 02 12 2008
We are in search of potential
partners for:
Performing joint scientific investigations
Cooperation in delivering billets made
from deformed iron.
35
Praha AIP 02 12 2008
From the scientific viewpoint
we are interested in:
Physical factors and mechanisms responsible for
iron hardening during hot deformation
Computer simulation of iron hardening processes;
Tribotechnical tests
Investigation of iron physical characteristics
Construction of mathematical models of structure
formation
Investigation of fine structure (dislocations and
point defects).
36
Praha AIP 02 12 2008
From the practical viewpoint
we are interested in:
Widening the area of deformed iron use as an
effective competitive alternative to steel roll stock
for manufacturing automotive and machinebuilding parts
Joint realization of our technological
developments during production of items from
deformed iron with improved characteristics
We are now prepared to produce rods for
investigations as well as gear and sealing ring
billets of various typical sizes
37
Praha AIP 02 12 2008
Contacts:
Physical-Technical Institute of National Academy
of Sciences of Belarus
10 Kuprevich St., Minsk, 220141, Belarus
Artur I. Pokrovsky, Cand. Tech. Sci.,
Leading Scientific Worker
Tel.: +10375-29-663-58-38
Е-mail: arturu@tut.by
38
Praha AIP 02 12 2008
Thank you
for attention!
39
Praha AIP 02 12 2008
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