On 2018-08-08 14:48:54
Common heat treatment methods and applications of steel
Description: annealing is to heat steel pieces (or billets) to a suitable temperature, keep them warm for a period of time, and then slowly cool them down (generally furnace cooling).
Application: used to eliminate the internal stress of casting, forging and welding parts, reduce the hardness, so as to facilitate cutting, refine metal grains, improve structure and increase toughness.
Description: normalizing is to heat the steel to the phase transition point above 30 ~ 50℃, heat preservation for a period of time, and then in the air cooling, cooling rate faster than annealing.
Application: used for heat treatment of low and medium carbon structural steels and carburized parts to refine the microstructure, increase strength and toughness, reduce internal stress and improve cutting performance.
Description: quenching is to heat steel to a certain temperature above the phase transition point, keep it warm for a period of time, and then put it into water, salt water or oil (some materials in the air) to cool down sharply, so that it gets a high hardness.
Application: used to improve the hardness and strength limit of steel. But quenching causes internal stress to make the steel brittle, so it must be tempered after quenching
Note: tempering is the process of heating brittle steel to a temperature below the phase transition point, holding it for a period of time, and then cooling it down in air or oil.
Application: used to eliminate the brittleness and internal stress after quenching, improve the plasticity and impact toughness of steel
Quenched and tempered
Description: high temperature tempering after quenching
Application: used to make steel with high toughness and sufficient strength, many important parts are tempered and heat-treated
Description: quench the surface of parts only. The surface of the parts has high hardness and wear resistance, while the core keeps the original strength and toughness
Application: commonly used for heat treatment of gear surfaces
Description: heating steel ≤ 120 ~ 130℃, after a long time heat preservation, with the furnace or take out in the air cooling
Application: used to eliminate or reduce the micro stress after quenching, prevent deformation and cracking, stabilize the shape and size of the workpiece and eliminate the residual stress of machining
Description: carburized the surface, carburized layer depth 04 ~ 6mm, hardness of 56 ~ 65HRC
Application: increase wear resistance, surface hardness, tensile strength and fatigue limit.
Suitable for low - carbon, medium - carbon (w c < 0.04%) medium - sized parts and large heavy - duty, impact, wear - resistant parts.