How to differentiate among annealing, normalizing, quenching and tempering

Annealing, normalizing, quenching, tempering... can you differentiate the various heat treatments clearly? Heat treatments aim to improve mechanical properties while eliminating residual stresses and increasing machinability of materials. Treatments can be divided into two categories by purpose: preparatory heat treatment and final heat treatment.

Preliminary Heat Treatment

Preparatory heat treatments serve three main objectives: improving machinability, eliminating internal stresses, and providing good metallographic organization prior to final heat treatments. Such processes include annealing, normalizing, aging and tempering processes.

1)Annealing and normalizing

Annealing and normalizing are used for post thermal processing rough billets. Carbon content greater than 0.5% carbon steels and alloy steels needing reduced hardness easy cutting use annealing while those containing less than 0.5% need normalizing treatment to avoid sticky cutting sticky knives causing too low hardness cutting hardness; both procedures help refine grain structure for future heat treatment preparation, typically done after manufacturing is complete, rough machining before.

(2) Aging Treatment
Aging treatments are used to alleviate internal stresses created in the manufacture and machining of blanks.

To reduce transport workload and facilitate finishing process before arranging an aging treatment can reduce overall transport workload and improve general accuracy of parts. But for higher precision requirements such as coordinate boring machine boxes etc, two or multiple aging treatment processes should be set up, while simple parts generally cannot undergo this treatment process.

Cast parts (such as precision screws), to eliminate internal stress during production and ensure accurate processing, rough and semi-finish machining is often performed after rough machining to set multiple aging treatments in place; some shaft parts such as straightening processes also often include an arrangement for multiple aging treatments afterward.

(3) Tempering
Tempering refers to high-temperature tempering treatment after quenching high-temperature quench treatment, where uniform and meticulous tempering soxhite organization is achieved, for subsequent surface quenching and nitriding treatments to reduce deformation preparation purposes; tempering can also be used as a preparatory heat treatment step.

Tempering can produce comprehensive mechanical properties in parts, which includes improved hardness and wear resistance without necessitating high hardness levels or wear resistance requirements. Therefore, tempering can serve as the final heat treatment process.

2.02 Final Heat Treatment Solutions.

Final heat treatment aims to enhance mechanical properties like hardness, wear resistance and strength.

1) Quenching
Quenching includes both surface quenching and overall quenching processes. Surface quenching is widely utilized due to deformation, oxidation and decarburization issues; additionally it offers numerous other advantages including high external strength and wear resistance with good internal toughness and impact resistance properties. To enhance mechanical properties in hardened parts requiring tempering or normalizing heat treatment prior to surface hardening as a preparatory heat treatment process; its general process route includes: material forging normalizing (annealing), roughing tempering semi-finishing tempering semi finishing semi finishing semi finishing before surface quenching before finishing.

2)Carburizing Quench

Carburizing quenching for low carbon steel and low alloy steel involves first increasing carbon content of surface layers of parts before quenching to produce hardness increases in both surfaces, while still maintaining strength, toughness and plasticity in core materials. Carburizing may be divided into overall or partial carburization depending on whether anti-carburizing measures (copper plating or anti-carburizing materials) need to be applied (copper plating is generally sufficient). Quench deformation generally falls between 0.5-2mm so carburizing process usually falls somewhere in-between semi-finishing and finishing processes.

Process routes generally follow this flow: material - forging - normalizing - roughing, semi-finishing - carburizing quenching - finishing. When partial carburizing of non-carburizing parts is used to increase margin and remove excess carburizing layer during process plans, such as with margin increase/extra carburizing layer removal measures after carburizing before quenching is recommended.

Nitriding Treatment Nitriding involves penetrating nitrogen atoms through metal surfaces in order to form a layer of nitrogen compounds on them, producing a layer that improves surface hardness, wear resistance, fatigue strength and corrosion resistance of parts. Due to lower treatment temperatures and small deformation of thin-walled parts (generally not exceeding 0.6-0.7mm thickness) which means less deformation upon nitriding, thus making this process ideal for stress relief in cutting after high-temperature tempering processes after cutting after stress relief through high temperature tempering processes after cutting after cutting processes have taken place.