Induction surface (case) hardening of hollow shafts has unique features compared with hardening of solid shafts. With solid shafts, the core temperature typically does not rise significantly during heating. The relatively cold core compli- ments spray quenching by increasing the cooling intensity of shaft surface (cold-sink effect)[4,5]. By comparison, with hollow shafts, the cold-sink effect [...]
Austenitic stainless steels are not hardenable but like most metals suffer from work hardening both during the manufacture of the tube and during later processes. Annealing which is also sometimes referred to as solution heat treatment not only recrystallises the structure but dissolves carbides back into the austenite. Annealing temperatures range from 1050oC to 1150oC [...]
Fine prints became one of the characteristics of our life. It turned into a normal practice to be aware about fine prints of disclosure in every aspect of life whenever we are buying goods or listening to advertisements, taking medicine or purchasing service. In many cases “fine prints” consist of more important information than the [...]
Surface hardening of carbon steel and iron is one of the most common forms of heat treating by induction. The goal in surface hardening is to provide a martensitic layer on specific areas of the workpiece to increase hardness and wear-resistance while allowing the remainder of the part to be unaffected by the process. Click [...]
The selection of principal process parameters, such as power, frequency and coil length, is a function of the metal to be heated, the required temperature uniformity, billet size and other parameters. Depending on the application, power ratings from hundreds to thousands of kilowatts and frequencies from 60Hz to 10kHz are commonly used. Click here to [...]
Silver alloy plating is commonly used in an attempt to improve coil life and reduce electrical resistance of coil clamping areas for clamshell inductors. Unfortunately, it does not appreciably improve coil life. The life of a clamshell inductor usually does not exceed 10,000 heats, and only 3000 or 4000 heats is not uncommon. Click here [...]
Tempering is always a reasonable comprimize between maintaining the required hardness and obtaining low-stress, tough and ductile microstructure in the metal. Generally speaking, there are two different types of stresses: thermal stresses and stresses due to phase transformation. Thermal stresses are caused by different magnitudes of temperature and temperature gradients. Phase transformation stresses occur due [...]
In other applications such as strip or plate heat treating and coating (galvanizing, galvannealing, galvaluming, nonmetallic coating, and paint drying, for example), the ability to move the induction coil from the heating position to an off-line position is considered an important system requirement. Solenoid induction heaters with water-cooled “doors” are sometime used for such applications. [...]
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