Skip to main content

What is Induction Hardening In Heat Treatment of Metals ?

 Induction Heating has proved satisfactory for many surface hardening operations as required on the bearing areas of  the crankshafts , camshafts, axle shafts, and similar wearing surfaces. It differs from ordinary case - hardening practice in that the analysis of the surface steel is not changed, the hardening being accomplished by an extremely rapid heating and quenching of the wearing surface which has no effect on the interior core. The hardness obtained in induction hardening is the same as that obtained in conventional treatment and depends on the carbon content.


In this process, a high - frequency current of about 2000Hz is passed through a copper inductor block which acts as a primary coil of a transformer. The block is placed around but does not touch the surfaces to be hardened. The heating effect is due to the induced eddy current and hysteresis loss in the surface material. The hardening temperature is about 750*C to 760*C for 0.5 % carbon steel and 790*C to 800*C for alloy steel. The heated areas are then quenched immediately by sprays of water delivered through numerous small holes in the block. Both automatic and hand control can be employed. A depth of case of approximately 3mm is obtained in about 5 seconds. 

Although the equipment cost is high, it is practiced by the advantages of the process used, which include fast operation, freedom from scaling, clean operation, little tendency for distortion, no manual handling of the hot parts, and low treating cost. Medium carbon steel has proved satisfactory for parts, and the nature of the process has practically eliminated the necessarily for using costly alloy steels. 


Labels:

Comments

Post a Comment

Popular posts from this blog

MELTING FURNACES FOR FERROUS METALS : CUPOLA AND ITS WORKING

Various types of melting furnaces are used in different foundry shops, depending upon the quantity of metal to be melted at a time, and the nature of work that is carried out in the shop.  The primary objective in cupola is to produce iron of desired composition, temperature and properties at the required rate in the most economical manner. Besides, this furnace has many distinct advantages over the other types, e.g., simplicity of operation, continuity of production, and increased output coupled with a high degree of efficiency.  Description Of a Cupola : The Cupola Furnace consists of a vertical, cylindrical steel sheet, 6 to 12 mm thick, and lined inside with acid refractory bricks or acid tamping clay. The refractory bricks or the tamping clay used consist of  silicon oxide acid (SiO2) and alumina (Al2O3). The lining is generally thicker in the lower where the temperatures encountered are higher than in the upper region. The shell is mounted either on a brick work fo...
Post a Comment
Read more

SIMPLE CARBURETOR - CONSTRUCTION AND WORKING

CONSTRUCTION OF SIMPLE CARBURETOR :  The main Components of Simple Carburetor are : Float Chamber, float, nozzle, venturi, throttle valve, inlet valve, and metering jet . In the float chamber, a constant level of petrol is maintained by the float and a needle valve.  The float chamber is ventilated to atmosphere.  This is used to maintain atmospheric pressure inside the chamber. The float which is normally a metallic hollow cylinder rises and closes the inlet valve as the fuel level in the float chamber increases to certain level. The mixing chamber contains venturi, nozzle and throttle valve. The venturi tube is fitted with the inlet  manifold. This tube has a narrow opening called venturi. A nozzle is provided just below the centre of this venturi. The nozzle keeps the same level of petrol as that of the level in the float chamber. The mixing chamber has two butterfly valves.  One is to allow air into the mixing chamber known as choke valve. The other is to al...
Post a Comment
Read more

Advantages And Disadvantages Of Air Refrigeration System :

 Advantages Of  Air Refrigeration : 1. The refrigerant used namely air is cheap and easily available. 2. There is no danger of fire or toxic effects due to leakages. 3. The weight to ton of refrigeration ratio is less as compared to other systems. Disadvantages Of Air Refrigeration : 1. The quantity of  Refrigerant used per ton of refrigeration is high as compared to other systems. 2. The COP of the system is very low. Therefore running cost is high. 3. The danger of frosting at the expander valves is more as the air contains moisture content. 
Post a Comment
Read more