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Engine Valve |
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ENGINE VALVES
Two different types of valves are
used in internal combustion engines. The valves called Intake engine
valves let fresh air /fuel mixture get into the cylinder by opening
and closing the intake port. The valves called exhaust valves let
exhaust gas evacuate out of the cylinder by opening and closing the
exhaust port.
SPECIAL PURPOSE VALVES
A/S :BI
METAL VALVES
Exhaust valves are especially made from
bi-metal. The valves heads which sustain corrosion, deterioration,
mobile and mechanical forcement are made of austenitic steel and the
stems of the valves are made of martensitic steel because bi-metal
lengthens valve running time.
Na: VALVES FILLED WITH
SODIUM
The insides of some valves are filled with sodium
so that its heat can be decreased for the engines which run with
high speed in hard conditions for a long time so the possibility of
crack, corrosion and distortion decrease.
Ni:
NITRETED VALVES
Some valves are applied by nitration
process so that their deterioration and corrosion resistance
increase. Nitrated plate on the valves is non-fragile and doesn’t fall
into decay. Fatigue time can be increased till % 80 on high alloy
steel and % 40 on steel chrome - nickel portion % 8-18 by nitration.
The process decreases friction coefficient and increases correlation
resistance. Nitration decreases stickiness even if there is no
lubrication. These features lengthen valve durability.
ST: STELLITED VALVES
The satellite process is
applied onto exhaust valve and some inlet valve seats and stem tip
ends to increase their resistance
Y: VALVES WITH
HARDENED SEATS
Seats of Inlet valves are especially
hardened by induction to prevent detritions
Cr.CHROME
PLATED VALVES
Stem of valves are plated with chrome to
increase the surface resistance and decrease the detritions. The
process doesn’t only increase the stem resistance but it also
decreases functional power so it lengthens valve and guide
durability.
Ph: PHOSPHATE PLATED VALVES
Valves are plated with phosphate so that they can keep lubrication
and be protected from corrosion.
MATERIAL USED IN
VALVE:
N Alloy steel for intake
valves,also used as stem material for bimetallic versions is a
strong one for corrosions.
S CrSi is
exhaust valve steel with high resistance to both extreme
temperatures and corrosions, normally used to produce intake valves.
O (CrMo) –Steel with excellent wear
resistance and with low coefficient of friction is used for high
–stressed exhaust valves.
A (CrNiMn)
Austenitic CrNiMn – Steel for highly stressed exhaust valves, with
high resistance to both burning and corrosion is used as head
material with stellite facing for bimetallic versions, also not
effected by leaded fuel.
R Austenitic
(CrMoMn)– Steel with outstanding wear and heat resistance as well as
fatigue strength is used for highly stressed intake and exhaust
valves.
I Nikel – based super alloy for
large Diesel – engine exhaust valves is subjected to very high
stresses.
X Austenitic Chrome Manganese –
Nickel Steel with Nitrogen addition resitance to the corrosive
action and high strength properties at elevated temperatures is used
for exhaust valves and heavy duty inlet valves.
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Raw Materials Used In Valve |
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MALZEME ALAŞIMLARI / MATERIAL COMPOSITIONS |
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SİMGE /
SYMBOL |
S |
A |
O |
R |
X |
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MALZEME NO
/ MATERIAL NO |
1,4718 |
1,4871 |
1,4748 |
1,4785 |
1,4875 |
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DIN |
X45CrSi 93 |
X53CrMnNIN219 |
X85CrMoV182 |
x60CrMnMoVNbN 2110 |
X55CrMnNIN208 |
KİMYASAL
ANALİZ/
CHEMICAL ANALYSIS |
% |
% |
% |
% |
% |
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C |
0.40-0.50 |
0.48-0.58 |
0.80-0.90 |
0.57-0.65 |
0.50-0.60 |
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SI |
2.70-3.30 |
s0.25 |
s1.00 |
s0.25 |
s0.25 |
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Mn |
s0,80 |
7,00-10,00 |
s1,50 |
9,50-11,50 |
7,0-10,0 |
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P |
s0.040 |
s0.050 |
s0.040 |
s0.050 |
s0.050 |
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S |
s0,030 |
s0,030 |
s0,030 |
s0,025 |
s0,030 |
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Cr |
2.00-10.00 |
20.00-22.00 |
16.50-18.50 |
20.00-22.00 |
19.50-21.50 |
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Mo |
--- |
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2.00-2.50 |
0.75-1.25 |
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Ni |
--- |
3.25-4.50 |
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s1.50 |
2.00-2.75 |
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V |
--- |
--- |
0.30-0.60 |
0.75-1.00 |
--- |
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W |
--- |
--- |
--- |
--- |
--- |
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DİĞERLERİ
(En Çok)/OTHERS (Max) |
--- |
0.38-0.50 |
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0.20-0.40 |
ÇEKME
MUKAVEMETİ (N/mm2) /
TENSILE STRENGTH |
900-1100 |
950-1200 |
1000-1200 |
1000-1250 |
900-1150 |
LINEER GENLEŞME KATSAYISI
(20°C-700°C)(cm/cm
°C)X10'
LINEAR EXPANSION COEFFICIENT |
13.9 |
18.5 |
12.5 |
18.5 |
18.5 |
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