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Gloucester
Heat Treatment Ltd - DO IT ONCE... DO IT RIGHT... SAVE MONEY... SAVE TIME
Gloucester Heat Treatment Limited,
is a major supplier of specialist heat treatment services, for ferrous and non
ferrous materials, to both commercial and aerospace industries.
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The process called sulfinuzing was
developed many years ago to increase the resistance to scuffing and
frictional wear, together with increasing fatigue resistance and
fretting of many ferrous metal components. Sulfinuz is a low
temperature salt bath treatment generally operated in the region of 570°C
to 600°C, depending on material used. Treatment times at these
temperatures vary from five minutes to three hours, components may be
air cooled or quenched into hot water, depending on material and
geometry of the component, and also the distortion factor.
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Basically the treatment is a salt bath nitriding
process, which over 50 years has proven to increase the life and performance of
many components, such as extrusion dies, pistons, valves and crank shafts.
Stress
Relief
Parts which have been heavily formed, machined, cut or are fabricated by
welding, have high internal stresses. The part or assembly can be made
stress free by heating to a certain temperature, where the stresses will
be removed by thermal relaxation, without affecting the mechanical
properties of the part. The resultant part will be far less prone to
warp change dimensions, during further processing or use. |
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Thermal stress relieving can be performed on various materials,
including plastics, aluminiums, steels and alloys.
Maximum load size is 12ft x 6ft x 4ft - 8ft high.
Nitriding
Nitriding produces a case depth enriched in nitrogen, which diffuses
into the surface of the components, combining with nitride forming
elements. The steels chosen for nitriding are usually in the heat
treated condition, and fully stabilised, at a temperature above that of
the nitriding operation. The nitrogen is provided from the breakdown of
ammonia gas, which flows through the sealed retort at a rate determined
by the dissociation, which is continually measured.
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A compound layer is produced during nitriding, which is generally
considered beneficial, this layer offers corrosion resistance. However,
compound layers above 20 microns thick can be prone to spalling, and are
very often removed after the nitriding treatment. With the modern
methods of controlling the gaseous atmosphere, the compound layers can
be controlled to requirements.
Surface hardness's far in excess of conventional case hardening are
achieved without quenching and eliminates all but the very minimum of
distortion.
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| Aluminium
Aluminium and its alloys can be
subjected to a variety of thermal treatments, such as:- Solution
treatment, natural ageing, artificial ageing, annealing and stabilising
or stress relieving.
The purpose of heat treating aluminium is to increase the strength and
hardness of the alloy. Solution heat treatment on its own, initially
increases the ductility of alloys, and enables a certain amount of cold
working to take place, i.e bending, forming, stretching, before natural
ageing starts to harden the metal.
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Natural ageing increases the strength of the alloy, but artificial
ageing is far better. Annealing, softens the alloy, to allow extreme
bending and forming to take place, and stress relieving or stabilising
is the relief of residual internal stresses, which is carried out at a
predetermined temperature, which takes into consideration the mechanical
properties of the alloy, taking care not to alter these properties.
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| Atmosphere
To produce the required furnace
atmosphere, a gas must be conditioned to the carbon potenetial required,
for either hardening and tempering or carburising/casehardening.
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The gas in our case, is Endothermic, which is enriched with natural gas,
to produce the required carbon potential. This is measured by means of
an Automatic infra red C02 gas analyser. Which is calibrated before each
furnace run, using a certified calibration gas traceable to national
standards. Endothermic gas, produces an environment, which does not
allow the work to scale, and with automatic computer controlled
measurement, carburisation and de-carburisation can be eliminated.
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The pit furnace used at Gloucester Heat Treatment is capable of heat
treating loads 48? high x 28? diameter. With either oil quenching or
salt bath quenching facilities.
Salt Bath
Salt Bath Heat Treatment has many
advantages. When heat treating parts of thin wall section, salt being a
liquid medium gives support to the parts being treated, avoiding
unnecessary distortion. Heat transfer into components is very rapid and
uniform. Salt bath gives the Heat Treater flexibility, with various
Quenching methods, i.e oil, water, polymer, or into another salt bath
for Marquenching or Austempering.
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Protection from oxidation and
decarburisation is given by the salt during heating and also during the
transfer to the Quench.
When Carburising or case hardening in salt baths, case depths can be
very tightly controlled, and the shallow case depths are achieved with
ease. End only treatments are a useful plus for salt baths, as this can
eliminate the expensive cost of plating or remachining.
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Gloucester Heat Treatment has at present a total of 15 salt bath
furnaces with associated Quench facilities.
Heat Treatment Processes
- CONSULTANCY & MATERIALS ADVICE
SERVICE
- ANNEALING IN AIR
- ANNEALING IN ATMOSPHERE
- ANNEALING IN SALT BATH
- ANNEALING CYCLIC
- ALUMINIUM
- AUSTEMPERING
- CASE HARDENING SALT BATH
- CASE HARDENING ATMOSPHERE
- CARBURISING SALT BATH
- CARBURISING ATMOSPHERE
- CYANIDING
- CARBONITRIDING
- CARBON RESTORATION
- DIE STEELS
- CASTINGS
- FORGINGS
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- MARTEMPERING
- MARAGEING
- NITROCARBURISING
- GASEOUS NITRIDING
- NORMALISING
- PRECIPITATION HARDENING
- SOLUTION TREATMENT
- STABILISING
- STAINLESS STEELS
- STRESS RELIEVING
- SULFINUZING (SALT BATH NITRIDING)
- SHRINK FITTING
- TEMPERING
- THROUGH HARDENING
- TEST PIECE MANUFACTURE (FULL
MACHINING)
- TOOL STEELS
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Telephone contact numbers:
01452 526 434 and 01452 307 300
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