Simple description of heat treatment

From the stone age progressed to the bronze age and the iron age, heat treatment factory the role of heat treatment is gradually recognized by people. As early as 770 BC 222 years ago, the Chinese people in the production practice has been found that the performance of steel will change due to temperature and pressure deformation. An important process of softening treatment of white cast iron is manufacturing tools.
In sixth Century BC, iron and steel weapons were gradually adopted, in order to improve the hardness of steel, quenching process has been rapid development. China Hebei Yixian Yan are unearthed two swords and a Ji, the microstructure is martensite presence that is after quenching.
With the development of quenching technology, people gradually found that the influence of quenching medium on quenching quality. Three Shu Pu Yuan in this Shaanxi Valley as Zhu Geliang chipped 3000 knife, it is sent to the Chengdu Water quenching. This shows that the Chinese ancient times to pay attention to the different water quality of the cooling capacity, but also pay attention to the oil and water cooling capacity. Sword unearthed in China of the Western Han Dynasty (BC 206 ~ ad 24) Zhongshan Jing King's tomb, the core containing carbon content of 0.15 ~ 0.4%, while the surface containing carbon content is higher than 0.6%, indicating that has used the carburization process. But as a personal “ the technology ” the secret, refused to rumor, and thus the development is very slow.
In 1863, British metallography scientists and geologists show steel under a microscope in six different microstructure. It is proved that the steel during heating and cooling, internal will take place the organization change in steel high temperature phase in rapidly cooled into a hard phase. Allotropism theory Osmond French establishment of iron, and the British Austin the earliest formulation of the iron carbon phase diagram, for the modern heat treatment process initially laid the theoretical foundation. At the same time, we also study the protective method of metal in the metal heat treatment heating process, in order to avoid in the heating process of metal oxidation and decarbonization.