SU378442A1 - METHOD OF THERMAL TREATMENT OF STEELS OF TRANSITIONAL AND MARTENSIC CLASSES - Google Patents

Description

one

The invention relates to the field of heat treatment.

There is a method of thermal processing of transition and martensitic steels, which consists in quenching, cold working and aging (tempering).

 Structural transformations occurring during cold treatment in the part volume determine equivalent properties across the cross section, while schrach, ka, k in some cases it is necessary to obtain high hardness and surface strength at the BYAZ, COY and plastic core.

The purpose of the invention is to increase the plasticity while maintaining a high level of steel strength.

This is achieved by cold treatment of only the surface layer.

The technology of processing parts according to the invention includes the following operations:

. Hardening with temperatures ensuring the formation of a two-phase structure “austenite + martensite.

2. Cold treatment of the surface of the part, pr, and in which a martensitic structure is formed in the surface ODM layer, and the austenite + martensite structure is preserved in the core.

The size of the layer in which the structural transformations take place at treatment below 0 ° is controlled by the prolongation of the exposure and the cooling temperature.

3. Aging (or tempering), during which dispersion hardening processes occur in maftense, leading to an increase in hardness and strength. At the same time, at these temperatures, the diopersional solid state of austenite does not leak, thus a cm – m pattern, the core remains sufficiently viscous and

ductile.

Using the method of processing products made from steels having a temperature Mn close to zero, improves the strength and hardness of the surface.

layer, and for steels of the martensite-aging class with a higher martensite, the first point is to increase the strength of the top layer while maintaining a high level of ductility and toughness of the core.

Example. 1Truto, to a diameter of 18-22 mm from steel XI6H6, processed by the proposed method: quenching from 1000 ° C, cooling in water, (Short-term cold treatment in a liquid refrigerant with subsequent release 425 ° - 1 hour, allows you to get with a hardness in the surface m layer with a depth of 1-5, and. and a tensile strength of av 125 - 140 kg / mm, and in the rest of the bar

Av 95-110 kg / mm. 3. The method of heat treatment of steels of the transition and march of the classes, including quenching, cold working and aging, characterized in that, in order to increase the ductility of the surface layer, it is cold. the house is subjected only to the surface layer,