Technical Informations

What is quenching in heating treatment?

The quenching of steel is to heat the steel to a temperature above the critical temperature Ac3 (hypoeutectoid steel) or Ac1 (hyper-eutectoid steel), and keep it warm for a while to make it all or part austenitized, and then cool it at a critical cooling rate. A rapid heat treatment process for martensite (or bainite) transformation below Ms (or isothermal near Ms). The solution treatment of materials such as aluminum alloys, copper alloys, titanium alloys, tempered glass, or heat treatment processes with rapid cooling processes is also referred to as quenching.

Purpose of quenching:

1, Improve the mechanical properties of metal materials or parts. For example, improve the hardness and wear resistance of tools, bearings, etc., improve the elastic limit of the spring, and improve the comprehensive mechanical properties of the shaft parts.

2, Improve the material properties or chemical properties of certain special steels. Such as improving the corrosion resistance of stainless steel, increasing the permanent magnetism of magnetic steel.

When quenching and cooling, in addition to the reasonable selection of quenching medium, there must be a correct quenching method. The commonly used quenching methods mainly include single-liquid quenching, two-liquid quenching, fractional quenching, isothermal quenching, and partial quenching.

Steel workpieces have the following characteristics after quenching:

1, Unbalanced (unstable) structures such as martensite, bainite, and retained austenite are obtained.

2, There is a large internal stress.

3, Mechanical properties cannot meet the requirements. Therefore, steel workpieces are generally tempered after quenching.

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