This type of steel heat treatment and other metal alloys allows to obtain elements of increased hardness but at the same time of increased brittleness, which makes them more subject to cracking. Such treatment is performed at different temperatures, depending on steel grade. The process consists in heating steel elements and keeping them at particular temperature and then cooling. Depending on what we want to achieve, we select cooling time and environment in which the whole process will be carried out: oil, water, air or salts. It is important to reduce stresses and strains which occur during the change of structure of processed material- the best effects are achieved if we apply quenching with isothermal process.
This advanced type of metal heat treatment is conducted at high temperatures. It consists of austenitization at temperature of 800-1200 °C and then quick cooling and tempering in order to maintain the structure of martensite or bainite. This treatment allows to obtain exceptionally high steel hardness and strength.
This kind of heat treatment, also referred to as case hardening, is used to increase material hardness and its abrasion resistance, maintaining softness and core ductility. Such effect may be obtained by carburizing the near-surface layers of steel with coal. We need to remember that this type of heat treatment is used only with steels of carbon content up to 25%. When carburizing, steel is heated to temperature of 850-900 °C.
Carburizing time lasts from 3 to 20 hours, depending on thickness of surface layer in which changes are about to occur, being the result of carburizing. Subsequently, treated elements are subject to quenching and tempering.
Sacher Company, having technologically advanced furnaces, is able to offer also modern technology of Piro-carb vaccum hardening. It does not cause oxidations or material deformations and leaves clean surface o workpieces. It is faster than conventional carburizing and due to energy consumption reduction is more environmentally friendly.
Annealing is used to reduce hardness and stresses generated as a result of mechanical processing or heat treatment. Its distinctive feature is longer duration and very high temperature as compared to other types of heat treatment.
We distinguish two types of annealing:
Soft annealing is performed to reduce the hardness of steel elements, which require mechanical processing. The elements are heated below the transformation temperature and kept for 5-10 hours and then slowly cooled.
Stress relief annealing is applied to remove or reduces stresses generated during welding, hammering, cold forging and thick workpiece machining. Steel is heated to temperature above quenching temperature, kept for 4-6 hours and then slowly cooled.
Tempering is a process which is necessary after each steel quenching. It allows to remove stressed generated during heat treatment or chemical heat treatment and to achieve desired hardness of workpieces. Vacuum tempering consists in repeated heating and then cooling down steel material. It does not cause oxidation of workpieces.
Depending on temperature, we can distinguish the following:
Snap tempering used to remove quench stresses. It takes place without changing the steel hardness achieved during quenching.
Medium tempering used in spring tempering. The effects of tempering are changes in crystalline steel structure, which results in brittleness reduction at the same time maintaining hardness and elasticity.
High tempering used to increase steel resistance to dynamic load with high amplitude.
This metal heat treatment consists in nitrogen saturation of surface layers, which increases their abrasion resistance and fatigue strength and also corrosion resistance. It is performed in vacuum. As heating and cooling down processes are slow, plasma nitriding considerably limits the occurrence of deformations and stresses. Subsequently, surface grinding or other mechanical processing is not required and this type of treatment is possible to apply in case of steel types which are difficult to quench.
Active screen plasma nitriding( ASPN) provides uniform formation of nitrides reflecting the shape of workpieces without creating “ white”layer. This effect is obtained by plasma glowing, which activates nitrogen on the mesh and on nitrided workpiece, which guarantees that there will be no damage or charring effect caused by too excessive plasma dischargers on the workpiece.
Tool steels, steels to be carburized, high-chromium and stainless steels are subject to nitriding. effective layers reach 0,5 mm and achieve hardness range between 700 to 1300 HV.
It is a process of connecting metals in vacuum furnaces using soldering materials.
It is characterized by high purity, lack of overheating and stresses and very high strength of soldering connection. Within once cycle, we can connect soldering and quenching.
Cleaning and degreasing are essential before each heat and chemical treatment and soldering. Clean-Tec technology implemented by Sacher Company provides high standard of surface preparation before technological process. Used chemical agents are neutral as regards the environment and people. Cleaning temperature is 40°C.