Sorbitized Precision Steel Tube (5.50) for Auto Parts. The original name was "lead quenching method". Since the 1950s, our country has heated the steel wire to the austenitization temperature and then immersed it in the lead bath to the temperature near the nose of the isothermal transformation diagram. The isothermal temperature is maintained until the austenitic decomposition is completed, and then theprecision steel pipeespecially used for automobile parts and cooled in air to obtain all or most of the sorbite structure. Self-heating and spontaneous tempering.
Previously, there was a general term of "spontaneous combustion", which was understood to mean that after the surface cooling of the precision steel pipe for automobile parts, the quenched parts of theprecision seamless pipefor automobile parts were heated and tempered due to outward heat conduction in the heart. However, from the in-depth study of low-carbon martensite, it is found that due to its high Ms point, tempering forms spontaneously in the cooling process ofprecision steel pipes for auto accessories, which is called spontaneous tempering. This is the process of heat transfer from the core of precision automobile steel pipes to the surface and tempering by heating. Natural stabilization (or natural stabilization treatment) (7.8).
Casting placed in the open air for a long time will cause casting stress relaxation, thus stabilizing the shape and size of the casting, which is usually called aging treatment in China. Although the English word "seasoning" can be literally translated as "aging", aging has been clearly defined in the specialty of heat treatment process of precision steel tubes for metal structures and auto parts, that is, after solution treatment or cold plastic deformation, its performance changes over time when placed at room temperature or at a slightly higher temperature.
The performance change of precision steel pipe materials especially used for automobile parts after aging is the precipitation of particles formed by diffusion of components, excluding the relaxation or elimination of internal stress. To avoid confusion, molded parts will be referred to as "natural (or natural) stability" rather than "aging." Distribution of carbon content (8.23). The carbon content of special precision steel pipe for auto parts refers to the carbon content in the whole or part of the steel parts, but there is no limited form. Its carbon concentration is limited to a solid solution in iron or carbon content of iron.
