What's the fastener heat treatment?

The fastener heat treatment

Heat treatment is the fastener through certain heating, keeping warm and cooling, so that its internal organization changes so as to obtain the expected performance, organization and structure of the process. Annealing, Normalizing, Hardening, Tempering is the heat treatment of the "four fires", of which the hardening and tempering are closely related, often used in conjunction with each other, one is indispensable.

Annealing is the workpiece is heated to the appropriate temperature and held for a certain period of time, and then slowly cooled, so that its internal organization to reach or close to the equilibrium state, so that the internal stresses generated by the previous process can be released to obtain good process performance and performance for further quenching as a preparation.

Normalizing is the workpiece is heated to the appropriate temperature after cooling in the air, the effect of normalizing similar to annealing, only to get a finer organization, often used to improve the cutting performance of the material, can be used for a number of low-demanding parts as the final heat treatment.

Hardening is the workpiece is heated and insulated, in water, oil or other inorganic salt solution, organic aqueous solution and other quenching medium for rapid cooling.

Tempering is the quenched workpiece at a higher than room temperature and lower than 650 ℃ appropriate temperature for a longer period of heat preservation, and then cooled, it can reduce the brittleness of the quenched workpiece.

Four fires with the heating temperature and cooling mode of different, and evolved a different heat treatment process. In order to obtain a certain strength and toughness, the hardening and high-temperature tempering combined process, known as tempering.