SU992599A1 - Method for protecting parts against oxydation - Google Patents

Description

(54) METHODS OF PROTECTING DETAILS FROM OXIDATION

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The invention relates to heat treatment and can be used to prevent the oxidation of metals during heat treatment or soldering in hydrogen with detonated hard solder and knots made of alloyed steels, such as stainless steel.

A known method of protection against oxidation, decarburization and crushing of parts during heat treatment, when the parts are placed in a graphite cup with the position fixed by fine powder (tg) 1.

However, this method due to high gas separation is not applicable for heat treatment of parts of vacuum devices and is all the more unsuitable for soldering parts in furnaces.

A known method of protection against oxidation is by lowering the oxygen content in the working area due to the combined use of vacuum and vapor of readily evaporated elements of G 21.

The container along with handles mine. a part introduces some amount of a lightly-boosted metal or a metal with a low boiling point, and after pre-evacuating the air, the container is heated. With this, a limited amount of oxygen remains in the container. determined by the internal volume of the container and the residual air pressure in it, in the process of heating the container, the residual oxygen oxidizes the surface of the part, if it does not: have a sufficient amount of film. The vaporized metal pair formed in the chamber space condenses on the cold walls and binds the free oxygen present in the chamber. Vacuum helps accelerate the process of metal evaporation. Since partial: the oxygen pressure in the chamber decreases sharply, the film dissociates on the surface of the soldered part.

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However, effective use of this method is possible only in a vacuum. In addition, it is necessary to carefully select all components involved in the process that are protected from oxidation; materials with high means to oxygen ineffective.

Also known is a method of protecting against oxidation by creating a local one. 0 reducing environment around the part, for example in a special container of hydrogen peu 3. In this case, soldering and annealing of high-chromium stainless steel components is carried out in a special container, built-in in the furnace chamber, and in the container are served sharply dried hydrogen with a dew point of minus 60-70 ° C, i.e. with a low content of oxygen in comparison with hydrogen in the total volume of the furnace. The disadvantage of the known method is the complexity of the technological process, which requires expensive and scarce equipment for additional fine purification of hydrogen. The quality of the spa depends on the stable operation of the hydrogen fine purifier. The purpose of the invention is to improve the quality of the spa. The goal is achieved by those in the method of protection against oxidation, mainly from alloyed steels, during their heat treatment, such as soldering in gaseous media, including creating a local reducing environment around the part, are created by placing the part with a gap in the mandrel of steel with a carbon content of 0, 3-2 wt.%. Due to the reaction between the carbon of the mandrel and hydrogen and oxygen in a narrow gap around the 1-10 mm piece, a microzone is created with reduced oxygen content compared to its content in the total furnace volume. Heating is performed in the atmosphere of the water of the genus, using conventional hydrogen. An increase in the gap between the mandrel and the part, as well as a carbon content in the mandrel of less than 0.3%, leads to an increase in the oxygen content in the microzone, and, consequently, to oxidation of the surface of the part. The carbon content in the mandrel in excess of 2.0% leads to carbonization details. The drawing shows a device for carrying out the method. Example. Such a mandrel is made of carbon steel, for example, St-3, which ensures the formation of a narrow gap of not more than 10 mm between the stand of the unit and the mandrel. Then, the burned node is assembled and placed in the mandrel as shown in the drawing. In the example, the mandrel consists of two parts; clamp 1 and body 2. Glass 3 and diaphragm 4 (the joint unit) are made of OOOH18N9 steel. Parts of the assembly are brazed with copper solder 5. Ceramic rings b and 7 provide the necessary clearance between the elements of the mandrel and the fired knot. The soldering process is carried out according to known conditions, usually used for brazing copper parts from unalloyed steels at 1,100 ° C. Mandrel can be used many times. The table shows the change in oxygen, carbon and quality of the spa after heat treatment (soldering) at 1100 ° C in three ways: in a container with fine purification of hydrogen (prototype technology). In the furnace with the usual purification of hydrogen outside the container and in the same furnace according to the proposed technology, when the part is in the mandrel. In the latter case, there is a reliable connection of parts in the nodes, good flow of copper on the surface of OOOX18H9 stainless steel and the absence of oxidation and carbonation, all this leads to an increase in the quality of the spa. The proposed method allows to obtain high quality joints of active materials, which could not be saved under normal conditions, and to reduce the technological process capacity by 11,000 rubles per unit of technological equipment by reducing the cost of complex equipment for fine purification of hydrogen, which leads to cheaper process.

Initial electroplating part 0.005 of the surface Soldering in dry hydrogen (using the pro0, 060 totip technology)

Claims (3)

Claims A method for protecting parts from oxidation, mainly from alloyed steels, during their heat treatment, such as soldering in gaseous media, includes creating a local reducing medium around the part, characterized in that, in order to improve the quality of the parts, the local reducing medium is created by placing the part with a gap in the mandrel of steel with a carbon content of 0.3-2 wt.%. Sources of information taken into account in the examination f. USSR Author's Certificate No. 293853, cl. C 21 O 9/22 1969. 2.Bsenberlin R.E. Soldering and heat treatment of parts in gas environment and in vacuum. L., Mechanical Engineering, 1972. 3.Labetsky V.V. Lebedev N. D., Menshikov A. V. Hydrogen dvukhkolpakov oven soldering and annealing parts high-chromium stainless steels. Elect “onna technique. Ser. 1, Microwave Electronics, 1973, vol. 5. p. 113116. No more than 10 tte more than 10