Metal structure and heat treatment knowledge

(1) Metal organization
1. Metal: A substance with opaque, metallic luster, good thermal and electrical conductivity, and its electrical conductivity decreases with increasing temperature, and is rich in ductility and ductility. A solid (ie, crystal) in which atoms in a metal are arranged regularly. 2. Alloy: A substance with metallic characteristics composed of two or more metals or metals and non-metals. 3. Phase: the component of the alloy with the same composition, structure and performance. 4. Solid solution: It is a solid metal crystal in which the atoms (compounds) of one (or several) elements dissolve into the lattice of another element while still maintaining the lattice type of the other element. The solid solution is divided into interstitial solid solution and Two kinds of replacement solid solution. 5. Solid solution strengthening: because the solute atoms enter the gaps or junctions of the solvent crystal lattice, the crystal lattice is distorted and the hardness and strength of the solid solution are increased. This phenomenon is called solid solution strengthening. 6. Compound: The chemical combination between alloy components produces a new crystal solid structure with metallic properties. 7. Mechanical mixture: An alloy composition composed of two crystal structures. Although it is a two-sided crystal, it is a component and has independent mechanical properties. 8. Ferrite: Interstitial solid solution of carbon in %26alpha;-Fe (iron with body-centered cubic structure). 9. Austenite: Interstitial solid solution of carbon in %26gamma;-Fe (iron with face-centered cubic structure). 10. Cementite: a stable compound (Fe3c) formed by carbon and iron. 11. Pearlite: a mechanical mixture composed of ferrite and cementite (F+Fe3c containing 0.8% carbon) 12. Leeburite: a mechanical mixture composed of cementite and austenite (4.3% carbon)

(Two), heat treatment

A process of changing the structure and performance of metal materials through certain heating, heat preservation and cooling in a solid state.

13. Annealing: a heat treatment process in which metal or alloy materials or parts are heated to phase change or partial phase change temperature, kept for a period of time, and then slowly cooled. 14. Normalizing: A heat treatment process in which steel is heated to a temperature above the complete phase change, kept for a certain period of time, and then cooled in air. 15. Quenching: a heat treatment process in which steel is heated to a phase change or partial phase change temperature, after a period of heat preservation, and then rapidly cooled. 16. Tempering: a heat treatment process in which the quenched steel is reheated to a certain temperature (below the phase transition temperature), kept for a period of time, and then cooled. 17. Quenching and tempering treatment: the steel parts are quenched and then subjected to high temperature tempering. This composite process is called quenching and tempering treatment. 18. Surface heat treatment: A heat treatment process that changes the surface structure or chemical composition of steel parts to improve the surface performance.