SU585221A1 - Method of heat treatment of bimetallic die forgings - Google Patents

Description

I. .

The invention relates to the processing of metal in pressure and can be used in; Instrumental-die-casting production in the manufacture; Piece of die forging. :

A progressive method of manufacturing parts of the mold - with the forming cavities is cold extrusion, which ensures the achievement of 8-11 classes of working surface roughness and 2-3 classes of accuracy in the design of forming cavities 1,. .- - /:;

The disadvantage of this method in particular with open extrusion of cavities is the limitation (lack of deformability of blanks from die steels due to the formation of cracks and unsatisfactory quality of reproduction. Composite-shaped cavities. small shtyoshpovyh products, because it is difficult to provide the necessary strength of the mater-stamps.

Overcoming difficulties is possible by using pre

2

; stamped bimetallic forgings, 1ec11, and prior to cold extrusion of the forgings, be subjected to such heat treatment, which ensures high base hardness and low resistance to deformation of the cladding layer. In the latter case, for | Extrusion of plastic strains is localized in a thin plaster layer under conditions of high hydrostatic pressure. This technique eliminates the formation of cracks and tears, at the same time improves the quality of reproduction of the extrusion of the cavity of the die product.

There is a terrific method (treatment of steel; containing 0.02-0.10%) after which, after hot deformation, it is heated to a temperature in the region from the crystallization temperature to a slow cooling from this temperature to (temperature; between point Ad and fast cooling to normal temperature, heating to ZOO-BSO C and slow cooling 2. The known heat treatment method (annealing) increases the plasticity of the material. However, it is not suitable for processing bimetallic die forgings under

cold extrusion of forming cavities using the above-mentioned technological method, due to the distribution of the forgings into the radial. direction in open extrusion.

The closest technical solution is a method of heat treatment of die bimetallic forgings, including heating the billet to the quenching temperature of the base steel (for 7X3 840-850С steel), holding for 45 hours and cooling with the furnace to 20-100 ° C t3j.

However, this method also does not provide the possibility of performing a holon extrusion of the forming cavity of a die product with a high quality of its reproduction, since the forging basis after the implementation of the method has a low resistance to plastic deformations.

The purpose of the invention is to expand the genetic capabilities of manufacturing stamped articles by the cold extrusion method by increasing the strength of the base with sufficient platichiness and low yield strength of the cladding layer.

This achieves by the fact that in an excellent method of heat treatment of die bimetallic forgings, including heating the forgings consisting of base and cladding steels, to the hardening temperature of the base steel, hardening and cooling, after holding the forgings are forced to a temperature in the interval between critical by points Aj of cladding and main steels, again forcing the austenite transformations of the cladding material, cool the forging in quenching mode corresponding to the grade of the base material and then Patent Application subjected to tempering in a base material mode.

The intensification of the bimetallic forging and its secondary holding in the interval of points Aj by the main and plating steels ensures the pearlite transformation of the austenite of the cladding material. This ensures, regardless of the speed of the last cooling of the forging, a low hardness of the cladding layer, which allows cold extrusion of the forming cavity of the die product.

Quenching and tempering of the billet with the original st) austenite structures (base and perlite (cladding layer) are given, compared to slow cooling from the same temperature, the base of the forging, high hardness and brittle strength without significant changes in the structure of the cladding layer. This ensures

the possibility of cold extrusion in the field of high hydrostatic pressure, which eliminates the formation of cracks and increases

playback quality of the extruded; cavity;

An example. The bimetallic forging of 5ХНТ steels (base) and ЗХ2В8 (cladding layer) is heated in the furnace to the temperature of Calcium

steel 5XHT (840 ° C), held for 4-5 hours to reduce internal stresses, and together with the furnace, heat up to 770-790 ° C. This temperature range is located

between points A of the main steel 5ХНТ (720С) and cladding steel ЗХ2В8 (810С).

Then the forging is again held in the furnace for 6-8 hours for

transformations of austenite cladding material and quenched in oil. After quenching, the steel in the 5XHT mode is performed immediately. As a result of doing

heat treatment cladding layer becomes hardness N T C 16- -20, and the base - NIS 46-48, which provides the ability to perform cold extrusion of the form-making

cavity stamp. Then the forging is stripped and transferred to cold extrusion operations of the cavity.

The present invention will expand the area of cold extrusion to die forging dies, which means that their accuracy and cost reduction for their manufacture can be increased. The economic effect that can be obtained by using the method in one enterprise will be 15-60 thousand rubles. in year.

Claims (3)

1. Graumanis Ya. V. and Rudzitis C, C, Injection of mold cavities of dies and molds. Riga LRINTIP, 1971J p. 5-12. 2, Patent CltlA 383905, 148-12, 1974. 3. Dovnar S. А. Thermal mechanics of hardening and destruction of bulk dies, stamping. M., Mechanical Engineering, 1975, p. 237-238.