Transcript PRECIPITATION HARDENING

COPPER ALLOYS
• Beryllium Bronze
1.75% to 2.5% Be, 0.5 % Co, balance Cu
Treated at 800oC , quenched, cold worked if
needed, then precipitation hardened at 2750C for
1 hour.
Tensile strength 1300-1400N/mm2
(for hammers, chisels, hacksaw blades in gas, oil,
mine, explosive fields)
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Al- Alloys,
Cr-Cu alloys, Zr-Cu, Ti-Cu,
K-Monel (Monel- Cu-Ni alloys),
Narcoloy (Al, Bronze- 7%Al, 0.5%Co, 0.25%Sn)
• Mg based alloys,
• Zn based alloys for dies
• (MAZAK)- excellent casting properties- for parts in
Washing machines, radios, Alarm Clocks, wiper motor
casing, door handles,etc.
• Titanium Alloys
• Shutter blades, surgical implants,
Detailed tables on these shall be supplied.
ABOUT ALLOY STEELS
PLAIN CARBON STEELS-
with upto 1% Mndue to deoxidation and desulphurisation processes
ALLOY STEELSCONTAINS > 01% Mo/V
>0.3%W/Co/ Cr
>0.4%Ni
>2%Mn
To improve & extend the properties of PCS,
To introduce new properties
Thus are costly – (Ni, Cr, etc. much costlier than PCT)
PIG IRON PRODUCTION
• Smelting of Iron Ore in Blast Furnace
shaft type furnace >60 m high, output of 10000 tonnes /day
Refractory lining to last for several years
• Ore, coke, lime stone charged to furnace through
top. preheated air blast through tuyeres near base at times
fuel oil injected to reduce coke consumption& increase output
• At intervals, tap hole & slag hole at bottom opened.
STEEL PRODUCTION
BY BESSEMER PROCESS,
L-D PROCESS
BASIC OXYGEN STEEL MAKING
(By Basic Oxygen Furnace)
• Reduction occurs in three stagesFe2O3
to Fe3O4,
to FeO,
then to Fe
Reaction in upper part of furnace. Iron remains
as a spongy mass
The earthy waste- GANGUE- combines with lime
to produce a fluid slag.
Gangue- composed of silica, will not melt at blast
furnace temp.
SPONGE IRON
Sponge Iron is a metallic product formed by
the reduction of iron ore at temperature just
below the fusion point of iron. This product
has derived the name "Sponge Iron" due to
its porous nature. It is also called as Direct
Reduced Iron (DRI).
A substitute of steel scrap for steel making through the secondary
route Replaces ferrous scrap as a coolant in LD converter. The value
of DRI is measured by comparing its cost and properties with those of
scrap.
It is free from elements like Copper, Zinc, Tin, Chromium, Tungsten
and Molybdenum etc that are usually present in scrap.
It has low Sulphur content. It has the ability to use low grade fuels and
fuels that are unacceptable for conventional iron making.
It is more suited for some special metallurgical processes than
conventional iron & steel products e.g. Precipitation of copper from
leaching solution during copper extraction. Production of metal
objects by powder compaction
PARTICULARS OF SPONGE IRON LUMPS
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TOTAL IRON - 91.5% Min
METALLIC IRON - 80% Min
DEGREE OF METALLIZATION - 88% Min
CARBON - 0.2% Min
SULPHUR - LESS THAN 0.04% Min
PHOSPHOROUS - LESS THAN 0.45%
GANGUE- LESS THAN 5%
NON MAGNETIC MATLS. - LESS THAN 0.5%
• SIZE - 3 to 20 mm
• Ancor MH-100: sponge iron powder which is the
P/M industry standard for producing low to
medium density parts with good compressibilityproduced by the direct reduction of high grade magnetite
iron ore. This process results in spongy particles
• Ancormet 101: sponge iron powder which was
developed to supply the P/M industry with a
powder grade that could be used for low to
medium density parts with higher strength
requirements
results in fast and uniform carbon pick-up during
sintering and permits shorter sintering cycles.
Dimensional change factors are lower especially in
copper steels.