{"id":7169,"date":"2024-07-26T15:53:49","date_gmt":"2024-07-26T15:53:49","guid":{"rendered":"https:\/\/www.h-metal.ro\/blog\/?p=7169"},"modified":"2024-07-26T15:53:50","modified_gmt":"2024-07-26T15:53:50","slug":"the-return-of-steel","status":"publish","type":"post","link":"https:\/\/www.h-metal.ro\/blog\/en\/the-return-of-steel\/","title":{"rendered":"The return of steel"},"content":{"rendered":"

Steel tempering<\/strong> is a final heat treatment that is always applied after hardening. It consists of heating the hardened steel to a temperature below the critical point AC\u2081, maintaining and cooling generally in the air.<\/p>\n\n\n\n

Heating temperatures are very different depending on the type of steel.<\/p>\n\n\n\n

There are 4 basic types of heat treatment of steel: annealing, normalizing, hardening, and tempering.<\/p>\n\n\n\n

Why is it necessary to return steel after hardening treatment?<\/p>\n\n\n\n

After hardening, steel has an unstable, hard and brittle structure. The characteristics of mechanical strength and hardness are high, but the characteristics of plasticity and toughness are low<\/p>\n\n\n\n

The tempering treatment is applied to steels that undergo physical transformations. Following this treatment, the unstable and fragile state changes to a more stable and less fragile state.<\/p>\n\n\n\n

RETURN OF STEEL – PURPOSE OF APPLICATION:<\/h2>\n\n\n\n

– elimination or reduction of internal stresses in steel parts after hardening;<\/p>\n\n\n\n

– transformation of the martensitic structure of the hardened parts into a more stable structure;<\/p>\n\n\n\n

– reducing frailty;<\/p>\n\n\n\n

– increasing tenacity.<\/p>\n\n\n\n

The tempering temperature is chosen according to the mechanical characteristics imposed on the piece.<\/p>\n\n\n\n

The hardness of the hardened part decreases with the increase of this temperature, and the toughness increases.<\/p>\n\n\n\n

The duration of heating depends on the dimensions of the part and has the purpose of not creating internal tensions in the material.<\/p>\n\n\n\n

Depending on the temperature, three types of returns are distinguished (see the table below).<\/p>\n\n\n\n

\"\"<\/a><\/figure>\n\n\n\n

By low tempering<\/strong>, the aim is to reduce the residual stresses in the hardened parts, without decreasing their hardness.<\/p>\n\n\n\n

High yield limits of the material of the treated parts, in order to ensure their good elasticity, are obtained after the medium tempering<\/strong>.<\/p>\n\n\n\n

And following the high tempering treatment<\/strong>, a piece with high mechanical resistance and good toughness is obtained.<\/p>\n\n\n\n

The tempering temperature influences the mechanical properties in that it determines the degree of dispersion of the carbides in the ferrite-carbide mixture.<\/p>\n\n\n\n

Hardening and low recovery can be grouped into a single operation called self-returning hardening<\/strong>.<\/p>\n\n\n\n

The high bounce is the most common of the three types detailed above.<\/p>\n\n\n\n

Return cooling is done in air, except for alloy steels susceptible to brittleness on return, which from temperatures 550-650\u00b0C cool quickly in water.<\/p>\n\n\n\n

H Metal <\/a>sells a wide range of metallurgical products subjected to heat treatments.<\/p>\n\n\n\n

To receive a concrete offer, please contact us at office@h-metal.ro.<\/p>\n

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