Method of handling cylindrical articles

 

(57) Abstract:

The invention relates to the production of steel products metal coated and can be used in the manufacture of cylindrical articles with chrome surface. Method of handling cylindrical articles includes mechanical processing, carburizing inner surface in a gaseous environment to ensure eutectoid state, heat treatment with obtaining troostite patterns and galvanic plating before the finishing machining. The technical result of the invention is to improve the operational characteristics of cylindrical products by increasing the strength of adhesion of the chrome coating on the base metal and increase the hardness of the base layer under the coating.

The invention relates to the production of steel products metal coated and can be used in the manufacture of cylindrical articles with chrome inner surface.

A method of processing steel products using electrolytic chromium coating (M. B. Cherkez. Chrome plating and zheleznenie. - M: motor cycle", 1958, S. 32-40). The method includes kanogo technical solutions are the limitations of its application with significant loadings (>250 N/mm2) working on a chrome surface. When operating under higher load may push the chrome layer and its destruction. If this is not provided in full cleanness of the surface, which degrades the performance characteristics of cylindrical products.

The closest technical solution adopted for the prototype, is a method of manufacturing steel wire drawing tool with chromium plating surface of the working channel (G. A. Savin. Drawing tubes. - M.: metallurgy, 1982, S. 150).

The method includes machining, cementation, subsequent heat treatment, plating and finishing machining. This ensures the hardness of the working surface of the drawing tool is not lower than HRC 58.

The disadvantage of this method is not sufficiently high adhesion of the chrome coating and the base metal due to the internal stress state of the martensitic structure of the base metal and high carbon content after cementation (about 0.8%). In the process, the product may flaking and chipping of the chrome coating from the base metal.

The technical problem solved by the invention, the bookmark is the accumulation of the chrome coating on the base metal and increase the hardness of the layer of the base metal under the coating.

The problem is solved by a method for handling cylindrical articles comprising mechanical processing, carburizing inner surface, heat treatment and electroplating plating before the finishing machining, according to the invention, the carburizing is carried out in a gaseous environment to ensure eutectoid condition of the inner surface, and heat treatment is carried out with obtaining troostite patterns.

When the carbon content is responsible eutectoid state, austenite is the most stable, which is important in the choice of thermal treatment conditions on troostite.

Carburizing the inner surface of the cylindrical article to eutectoid condition and heat treatment on troostite before and after machining to provide:

- high hardness (40-45 HRC) of the inner surface, which eliminates the possibility of rupture of the chrome coating at high loads;

small roughness (Ra<0,35 µm), due to the fine structure of troostite, well processed mechanically;

- high adhesion of chromium due to the lack of stress in enonomicheskoy products.

The method is implemented as follows. The inner surface of cold pipes size 57,156,325 mm of steel 22GU subjected to gas carburizing, in particular in the environment of natural gas. The pipe is heated in the coil to a temperature of 950-980oC. the Speed of their travel in the inductor is chosen from the condition of providing carburizing inner surface to 0.8%, a depth of 0.4 to 0.7 mm At the exit of the coil pipe is cooled by water supplied from a sprayer installed in the line. After quenching the pipe is subjected to tempering at a temperature of 325-375oWith providing troostite structure hardness HRC 40-45. The pipe is subjected to editing, rough honing as one of the types of machining and plating in the electrolyte (Σ2ABOUT3: 220-250 g/l; N2SO4: 2.3 to 2.5 g/l) at a temperature of 65-75oC. the Thickness of the chrome coating is 0,08-0,10 mm After finishing honing the inner surface roughness of the pipes was Ra<0.25 μm and an inner plated layer has a load of more than 400 N/mm2.

Using the proposed method of handling cylindrical articles with chrome inner surface can significantly improve their ekspluatatsionnika due to the increased strength of the base metal. This effect provides a wide use of cylindrical products in industry, particularly in the manufacture of cylinders sucker rod pumps for the oil industry.

Method of handling cylindrical articles comprising mechanical processing, carburizing inner surface, heat treatment and electroplating plating before the finishing machining, wherein the carburizing is carried out in a gaseous environment to ensure eutectoid condition of the inner surface, and heat treatment is carried out with obtaining troostite patterns.

 

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