Bearing steel annealing, quenching, tempering production principle - bearing knowledge

( A) 。 Annealing type 1. Completely annealing and full annealing and isothermal annealing weighing annealing crystallization, commonly referred to as 'for annealing, is mainly used for the annealing of hypoeutectoid composition of carbon steel and alloy steel casting, forging and hot rolled profiles, sometimes used for welding structure. Generally used as a final heat treatment, some not important artifacts or as a preliminary heat treatment in some artifacts. 2. Spheroidizing annealing fireball annealing is mainly used for the eutectoid carbon steel and alloy tool steel ( Such as manufacturing cutters, measuring tool and die steel used in the) 。 The main purpose is to reduce the hardness and improve cutting workability, and to prepare for after quenching. 3. The stress relieving the stress relieving (also called low temperature annealing Or high temperature tempering) , the annealing is mainly used to eliminate the casting, forging, welding parts, rolling, the residual stress of cold-drawn pieces, etc. If these stress will not be eliminated, will cause the steel after a certain period of time, or during subsequent machining deformation or cracks. ( 2) 。 In order to improve the hardness of quenching method, the main form is by heating, heat preservation, rapid cooling. Is the most commonly used cooling medium brine, oil and water. Brine quenching workpiece, easy to get high hardness and smooth surface, it is not easy to produce soft point of quenching is not hard, but it is easy to make the workpiece deformation is serious, even cracking. Oil as quenching medium is only applicable to the stability of the supercooled austenite bigger some alloy or carbon steel workpiece quenching of small sizes. ( 3) 。 Tempering 1. Reduce the brittleness, eliminate or reduce internal stress, there is a big internal stress after the steel quenching and brittleness, if not timely tempering will often result in deformation and cracking of steel. 2. To obtain the required mechanical properties of workpiece, the workpiece after quenching, high hardness and brittleness is big, in order to meet the requirements of different performance of various artifacts, can be tempered with appropriate to adjust the hardness, decrease the brittleness, get needed toughness and plasticity. 3. Stable workpiece size 4. For certain annealing softening hard alloy steel, the quenching ( Or normalizing) Often used after high temperature tempering, the carbides in the steel appropriate gathered themselves together, and will reduce hardness, and cutting.