Carburising Fluid Rx is basically pit-pot type fluid used for hardening / case carburising /carbonitriding of various components made of steel such as railway part, auto parts, gears, precision turned components, construction machinery parts and any other component needing hardening. By controlling the rate of flow by various means, neutral or carburising gaseous atmosphere can be created in the retort for carrying out processes such as annealing, carburising and carbonitriding. The fluid is generally known as carburising fluid, because of its more popular use for carburising or casing of steel.
Carburising Fluid Rx has been specially formulated for use in the single fluid drip process. This process has certain economic and practical advantages in the comparison with other known processes of Carburising.
PHYSICAL & CHEMICAL PROPERTIE
Colour & Appearance
: Yellow liquid
Sp. Gravity @ 30°C
Carburising with Carburising Fluid Rx is carried out in electrically heated pit type furnaces, which are usually designed for this type of a carburising operation. The carburised case depth depends on the time and temperature of the process.
PRINCIPLES OF USE
Carburising Fluid Rx gas carburising fluid is drip fed in retort type furnaces, at carburising temperature (above 800° C). It cracks in the furnace to form a gas having uniformly high carbon content. The atomic carbon available after a series of chemical reactions of this gas is absorted by the components to obtain a skin with high carbon content. The gas is chemically constant and gives duplicity of performance, batch after batch, unlike the unsaturated hydro-carbons sometimes used for this kind of operation. The Carburising Fluid Rx is so balanced in its composition that the maximum carbon potential which the gas acquires does not exceed more than adequate.
The Carburising Fluid Rx fluid meets the needs of most of the engineering components which require 0.75 to 0.80% carbon case.
SEQUENCE OF OPERATIONS
- Start the furnace to heat the retort to 800° to 850° C with the lid on.
- Open the lid and load in the preheated steel.
- Put on the lid, seal it, start the fan and let in the fluid at 0.2 ltrs/hour. Light the flame.Check the leaks around the lid and the mountings on the lid with a lighted match. Secure the leaks if any, restart the fluid drip and continue to heat to carburising temperature (900°C – 920°C). Observe the colour of the flame. It should be bluish.
- When the desired temperature of carburising is reached, increase the fluid drip to about0.8 – 1 ltrs per hour. Observe the change in the height and colour of the flame. It should be yellowish with a sooty fringe. At the same time insert test pieces into the retort through the escape vent port.
- After an hour remove one piece and check the progress of carburisation. The piece should be shiny gray and not sooty and should show some case.
- Continue heating and feeding at the constant rate till the desired %u2018case depth%u2019 is formed as seen by the checking of the other pieces which are removed at regular intervals.
- At the end when sufficient case is formed, any 1 mm – 1.5 mm as required, lower the feed rate to 0.2 litres /hour and continue heating at the same temperature of carburisation for about an hour to diffuse the carbon uniformly in the case.
- At the end of the process, the fluid should be stopped well above 700°C before the lid is opened.
Note: This article uses material from the http://rxmarine.com/