Views: 0 Author: Site Editor Publish Time: 2025-09-19 Origin: Site
In the field of metal processing and manufacturing, heat treatment processes are like a skilled chef's mastery of the heat of his ingredients, transforming the same raw materials into finished products with varying properties through different "cooking" methods. In 2025, with the rapid development of new materials technologies and the advancement of intelligent manufacturing, heat treatment processes are also undergoing new transformations.
This article will provide an in-depth understanding of the three most core heat treatment processes in metal processing—tempering, annealing, and normalizing—and reveal their respective secrets and applicable scenarios.
Annealing can be likened to a thorough "spa relaxation" for metal materials.
When metal undergoes cold working or casting, significant internal stress is generated, disrupting the grain structure. Annealing involves heating the metal above the critical temperature (typically 30-50°C above the Ac3 temperature) and then cooling it at an extremely slow rate (usually by furnace cooling). This process is like allowing a person who has been under prolonged stress to completely relax, allowing the atoms within the metal ample time to rearrange and form a uniform and stable structure. After annealing, metal materials become softer and significantly more ductile, making them ideal for subsequent cold forming.
Vacuum annealing technology is rapidly gaining popularity in industrial production in 2025. It allows heat treatment in an oxygen-free environment, preventing surface oxidation and making it particularly suitable for high-value-added products such as titanium alloys and precision components.
Normalizing is more like a scientific "fitness training program" for metal materials.
Unlike annealing, normalizing involves heating the metal to a slightly elevated temperature (50-80°C above Ac3) and then cooling it naturally in still air. This moderate "training" refines the metal's grain size and creates a more uniform and dense microstructure. The hardness and strength of the normalized material are significantly improved compared to the annealed state, while maintaining good machinability.
Industry practice in 2025 indicates that normalizing is increasingly replacing annealing for structural parts made of ordinary carbon steel and low-alloy steel. It not only shortens the processing time (often taking only half the time of annealing) but also achieves better overall mechanical properties. Normalizing is particularly popular in the mass production of automotive parts due to its high efficiency.
Tempering is a precise "property tuning" process.
It typically follows quenching, reheating the already hardened metal to a relatively low temperature (between 150-650°C) and then cooling it at a moderate rate. This process is like infusing a previously rigid personality with some flexibility.In the metalworking industry of 2025, advances in materials science will lead to multi-stage tempering processes becoming a new trend. By precisely controlling the holding time at different temperature stages, engineers can more accurately control key material properties such as strength, toughness, and wear resistance. Customized tempering processes can significantly extend the service life of high-value workpieces, such as tool steel and die steel.
