Archive for the ‘Heat treatment of steels’ Category
Friday, March 17th, 2006
It is proposed to deal with the effect of mechanical work on the structure and macro-properties of metals and to follow this with a classification of the processes used for mechanical working.
Effects of Mechanical Work on Metals
During the process of shape change which accompanies mechanical working the volume of the ...
Posted in Steels, Alloy Steel, Heat treatment of steels | No Comments »
Friday, March 17th, 2006
Applications for Induction Hardening
Induction hardening is primarily used for surface hardening. The heating process does not affect the core structure. It is possible to heat a material locally where it is functionally desired. Other sectors of the material remain untreated and it is easy to machine them.Induction hardening is in ...
Posted in Steels, Alloy Steel, Heat treatment of steels | No Comments »
Friday, March 17th, 2006
Rapid quenching of austenite to room temperature often results in the formation of martensite, a very hard structure in which the carbon, formerly in solid solution in the austenite, remains in solution in the new phase. Unlike ferrite or pearlite, martensite forms by a sudden shear process ...
Posted in Steels, Alloy Steel, Heat treatment of steels | No Comments »
Friday, March 17th, 2006
The traditional route to high strength in steels is by quenching to form martensite which is subsequently reheated or tempered at an intermediate temperature, increasing the toughness of the steel without too great a loss in strength. Therefore, for the optimum development of strength, steel must be ...
Posted in Steels, Alloy Steel, Heat treatment of steels | No Comments »
Friday, March 17th, 2006
Variations of thermal-spray techniques and the diversity of sprayable materials, along with advanced spray-control systems, have created new opportunities for the thermal-spray industry. Use of the process has grown well beyond the initial stage, and while its continuing importance in maintenance and repair is assured, thermal ...
Posted in Alloy Steel, Heat treatment of steels | No Comments »
Friday, March 17th, 2006
Liquid nitriding or nitriding in a molten salt bath employs the same temperature range as gas nitriding, which is 510 to 580°C. The case hardening medium is a molten, nitrogen-bearing, fused-salt bath containing either cyanides or cyanates.
Unlike liquid carburizing and cyaniding, which employ baths of similar compositions, ...
Posted in Alloy Steel, Heat treatment of steels | No Comments »
Friday, March 17th, 2006
Gas nitriding is a case-hardening process whereby nitrogen is introduced into the surface of a solid ferrous alloy by holding the metal at a suitable temperature in contact with a nitrogenous gas, usually ammonia. The nitriding temperature for all steels is between 495 and 565°C (925 and ...
Posted in Alloy Steel, Heat treatment of steels | No Comments »
Friday, March 17th, 2006
Tempering of alloy steels
The addition of alloying elements to steel has a substantial effect on the kinetics of the transformation, and also of the pearlite reaction. Most common alloying elements move the TTT curves to longer times, with the result that it is much easier to "miss" ...
Posted in Steels, Alloy Steel, Heat treatment of steels | No Comments »
Friday, March 17th, 2006
Martensite is a very strong phase but it is normally very brittle so it is necessary to modify the mechanical properties by heat treatment in the range 150-700°C. This process, which is called tempering, is one of the oldest heat treatments applied to steels although it is only ...
Posted in Steels, Alloy Steel, Heat treatment of steels | No Comments »
Friday, March 17th, 2006
Carbonitriding is a modified form of gas carburizing, rather than a form of nitriding. The modification consists of introducing ammonia into the gas carburizing atmosphere to add nitrogen to the carburized case as it is being produced. Nascent nitrogen forms at the work surface by the dissociation of ...
Posted in Steels, Alloy Steel, Heat treatment of steels | No Comments »