Main body

Metal Hardening

The use of this treatment will result in an improvement of the mechanical properties, as well as an increase in the level of hardness, producing a tougher, more durable item. Tempering is a process for heat treating steel to increase the hardness and strength thereof. Quenching has two steps: heating and rapid cooling. Heating aims to get the organization of metal crystals in a phase called austenitizing. The sudden cooling seeks the martensite structure.
 In the tempering heating is above the critical temperature, which is 727ºC. The purpose is to lead the steel at a phase in which is obtained the best possible arrangement of steel crystals, for future hardness. After this phase, the steel may be subjected to further stages, depending on the needs. The temperature in this phase is austenitizing temperature. Each steel has a composition, the temperature ranges from steel to steel. Quenching is achieved at different temperatures, depending on the piece of steel composition and its goals. Therefore, the quenching of a given piece takes into account many factors.
 The workpiece itself in exposure time austenitizing temperature is taken into account when make their temper. Each has a steel austenitizing temperature, and it is one that provides maximum hardness. This temperature is obtained within furnace, which may be flame or by electrical induction. Depending on customer requirements, austenitizing, and therefore tempering, will occur only in the part surface or across it.
 The second stage of cooling is quenching, which must be sharp in water. The rapidity of cooling is important to prevent the steel change to different phase from that obtained in the austenitizing temperature (more martensitic structure). Often, after hardening, the part is subjected to tempering.
After that, heating again and cooling in oil.