SU884856A1 - Method of producing articles from tungstem-free hard alloys - Google Patents

Description

(54) METHOD FOR OBTAINING PRODUCTS FROM UNLESS VOLUME SOLID SCREENS

I

 The invention relates to powder metallurgy, in particular, to methods for producing articles from metal powders, and can be used in the manufacture of tools from hard alloys for planting, cutting, sheet and bulk stamping, for drawing, etc.

A known method of producing products from hard alloys by molding a press out of a hard alloy, placing the press in a container with porous media, heating and hot pressing til.

The disadvantage of this method is that during the hot pressing process, porous medium is agglomerated to the surface of the deformable workpiece, the removal of which is a laborious process.

The closest to the proposed technical essence and the achieved effect is the method of obtaining products from hard alloys, which consists in pressing the products and further forming them by hot isostatic pressing in backfilling G 21.

A disadvantage of the known method is that when producing 11 products of tungsten-free hard alloys, there is interaction between the hard alloy and backfill, as a result of which a fused layer of compacted backfill is formed on the product, the removal of which is a labor-intensive operation. In addition, due to the difference in thermal expansion coefficients of the backfill material and the alloy during the mechanical removal of the surface layer, cracks are formed on the surface of the product.

The purpose of the invention is to eliminate the melting of the backfill material and the cracked ani.

Claims (2)

This goal is achieved by the fact that in the method of producing articles from tungsten-free hard alloys, including extrusion of products and hot isostatic extrusion, backfilling, after extrusion, the products are coated with the following composition about. %: Marshallite.25-45 Hydrolyzed solution of ethyl silicate Remaining When the content of marshalite is above 45 vol.%, The coating is poorly applied to the product due to its low flowability. When the marshalite content is less than 25 vol.%, A burn-out is formed on the surface of the hard alloy. The proposed method is carried out as follows. The components of the hard alloy are mixed in the right proportions and the blanks are molded at a pressure of 1-2 t / cm, and then a coating is applied consisting of 55-75% vol. And a hydrolyzed solution of ethyl silicate and marshalite 25-45 vol. on the sintered billet). After coating, the billet is placed in a steel container and covered with alumina powder (AljjQj). The billet container is heated to 1150–1300 ° C and deformed in a hot state at a pressure of 9001,100 Iffia. After cooling in air, the billet is removed from shell by tapping lightly. Example 1. A metal batch of composition 85% CrjCjj + 15% Ni is formed into a billet with a diameter of 20 mm and a height of 20 mm at a pressure of 1.5 ton / dm, and then a coating consisting of a hydrolyzed solution of ethyl silicate 55 vol.% and marshalite 45 vol.%. A solid alloy pickup is placed in a steel container with an outer diameter of 38 m and an internal diameter of 36 mm and a height of 38 mm, and powdered with alumina (AljGj) in such a way that the stock is in the center of the container. The resulting composite briquette is heated in a furnace in an atmosphere of dissociated ammonia to 1200 ° C and deformed in a closed die in hot atmosphere under a pressure of 1000 MPa. After air cooling, the hard alloy preparation is removed from the container by lightly tapping. The coating and transfer material alumina is easily separated from the deformed fabrication. There is no interaction of the intermediate coating with the carbide. The surface of the workpiece without a smooth layer and no cracks. Example2. From the carbide mixture of composition + 30% | (Ni + Mo) In a ratio of 4: lj, according to the technological process of Example 1, a blank is molded and coated with a hydrolyzed solution of ethyl silicate 75% by volume and marshalite 25% by volume, heated to 1300 ° C and pressed hot at 900 Iffla pressure. The removal of the cladding material (compacted alumina and coating) is carried out without difficulty, by gently tapping. On the surface of the workpiece, there are no cracks and a hot layer. EXAMPLE 3. In Example 1, 65% by volume of hydrolyzed ethyl silicate and 35% by volume marshalite are coated on the preform, heated to, and pressed in a hot condition at a pressure of 1,100 1-fl. The separation of the material of the shell occurs without difficulty, with the help of a light tapping. After separation of the shell, there are no cracks and a hot layer. Example4. According to the process of Example 1, the billet is sintered in a vacuum oven at 200 ° C and aged for 30 minutes to a density of 92% of the theoretical. Then the coating is applied, heated and pressed at a pressure of 1000 MPa. cooled in air and separated by gently tapping the casing from the workpiece. The removal of the casing is carried out without difficulty and neither a stiff layer nor cracks are found on the workpiece. The proposed method for producing articles of tungsten-free hard alloys makes it possible to obtain a product without a primed shell and without cracks with an easily detachable coating that protects the product from oxidation. Claim Invention A method for producing articles of tungsten-free hard alloys, including pressing of products and hot isostatic pressing in backfill, characterized in that, in order to eliminate baking of the material. on the back and cracking, sources of information, after pressing on the product, deposited into account during the examination coverage of the following composition, on L; 1. U.S. Patent 3,992,200 Marshalite 25-45kl. 1978 Hydrolyzed growth j 2. US patent f 3741756, , the thief of ethyl silicate Else. 75-223, 1976.