JPH02107717A - Method for nonoxidizing heat treatment of metal - Google Patents

Abstract

PURPOSE:To execute heat treatment to the surface of a material to be subjected to heat treatment such as a steel material in an excellent surface condition without converting in a heating furnace into a nonoxidizing condition by coating the surface with a coating material of which the powder of copper or copper alloy is formed into the shape of paste with a solvent, thereafter subjecting it to heat treatment in the air and peeling the coating material. CONSTITUTION:At the time of executing hardening and tempering treatment of a steel product, the surface of the steel product is coated with the one of which the powder or copper or copper alloy is converted into the shape of paste by a solvent such as a boiled oil and is thereafter subjected to heat treatment such as hardening and tempering. The surface of the steel product is not oxidized nor decarburized by the coating of a paste-shape coating agent even if the atmosphere in the heat treatment is not a nonoxidizing atmosphere but in the usual air, and, after the heat treatment, the coating agent is removed, by which the heat treated steel product having excellent surface condition can be obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is capable of heat-treating processed materials such as steel by preventing oxidation and decarburization without creating an oxygen atmosphere in a heating furnace. This invention relates to a non-oxidation heat treatment method for metals.

[Conventional technology]

Conventionally, heat treatments such as quenching and tempering were applied to the surface of processed materials such as steel while preventing oxidation and decarburization, for example by creating a vacuum in the heating furnace or injecting inert gas. those that are heat-treated in an oxygen-free atmosphere,
Container A made of cast iron or steel, as shown in Figure 4
Processed material C is immersed in salt bath agent B containing salts such as chlorides and poisonous substances, heat treated with burner D, etc., and then heated with CO2, argon, butane, etc., as shown in Figure 5. It is inserted into the inner cover B, which is made non-oxidized by injecting a protective atmosphere gas, and then heated to the heating coil G in the tempering furnace F. It requires expensive equipment to maintain this condition, and unless the surface of the processed material is polished after the heat treatment, unless a vacuum furnace is used, a product with the desired brightness cannot be obtained. There was a flaw in that it could not be used.

[Means 9 for Solving the Problems] In order to solve the above-mentioned defects, the present invention uses a coating material in which copper or copper alloy powder is dissolved in a paste in advance in a solvent, and then applied to the surface of the workpiece. After iH5 and heat treatment in a heating furnace,
By removing the paint from the surface of the processed material, a product with the required hardness and glossy surface can be obtained, and there is no need to polish the surface of the processed material after tempering, resulting in high dimensional accuracy. It is something that can be obtained.

〔Example〕

An embodiment of the method of the present invention will be described below with reference to FIGS. 1 to 3.

1st. The second figure shows a patch-type direct heating furnace l using a circular pit type burner as the heating source, and a heating/heater 3 is arranged at the bottom of the cylindrical heating furnace body 2. A guide wall 5 for guiding the hot air 4 along the inner circumferential wall 21 of the heating furnace main body 2 is arranged in a substantially arc shape on the hearth 22 with a required gap from the inner circumferential wall 21. A holding frame 9 on which a required quantity of workpieces 8 can be placed is mounted on a suspension frame 7 vertically disposed on the underside of the furnace lid 6 which opens and closes the top opening 23 of the furnace.
The latching rod 11 of the restraining means 10 is fixed to three stages with an appropriate number of steps.
The opening/closing means 12 of the furnace 46 can be freely engaged and detached.
is separately provided in the heating furnace main body 2, and the support rod 1 of the opening/closing means 12 protrudes into and sinks into the heating furnace main body 2.
The central part is pivoted to the top of the column 14 which is fixed in a vertical manner to 3.
The tip of the lever rod 16 is pivoted 18 to a protruding frame 17 protruding from the upper surface of the furnace cover 6, while a branch 20 with a required weight 19 suspended from the rear end is pivoted 7i' 21. It is what it is.

Further, FIG. 3 shows a tempering furnace 30 in which a supporting means for a workpiece 8 can be placed on a support 317, and air heated by a heating coil 32 can be discharged from an exhaust pipe 33. This is how it was done.

Therefore, when heat treatment such as quenching, tempering, annealing, etc. is carried out on the processed material 8 made of steel, powder made of copper or copper alloy is first added to a solvent such as boiling oil, for example, copper alloy powder; A paste-like paint is used by mixing the solvent at a potting ratio of 3:l, and this paint is applied to the surface of the workpiece 8 using a suitable applicator such as a brush, and then this is applied to the above-mentioned support. Place it on the holding frame 9 of the means lO
Then, with the rod 11 suspended from the hook 1 of the supporting means 10 on the suspension frame 7 of the furnace Z6, the opening/closing means 12 is operated to insert it into the heating furnace body 2, and the furnace lid 6 is closed.

In this case, one of the characteristics of the wood grain method is that there is no need to create an oxygen-free state in the heating furnace 1 by creating a special vacuum or injecting other inert gas.

In this state, the heating burner 3 is ignited, and the hot air is guided from the hearth 22 along the inner circumferential wall 2 by the guide wall 5 and rises, heating the inside of the furnace, and depending on the size and material of the workpiece 8, For example, JIS standard, SK, SKS, 545
In the case of C, SCM materials, etc., the quenching treatment is performed by heating at 850° C. for 15 minutes, or in the case of SKD materials, heating at 1000° C. to 1050° C. for the same period of time.

In this case, since its surface is covered with a paint made of copper or copper alloy, there is no risk that the surface of the processed material 8 will be liquefied, and furthermore, it can be safely decarburized and prevented.

Next, the weight 19 was lowered, and the lever 16 raised the furnace 6 to open it, and it was suspended on the back.]I! The workpiece 8 together with the holding means 10 is taken out from the heating furnace main body 2, immersed in an oil tank (not shown), oil-cooled at 40° C. for about 20 minutes, and then placed in the tempering furnace 30 shown in FIG. The processed material 8 is inserted together with the melon, and tempered by the heating coil 32 in the position fB placed on the support 31. The heating furnace 30
Exceptionally oxidized inside! Further, there is no need to heat-treat the workpiece C by surrounding it with an inner cover E in a non-oxidizing atmosphere as shown in FIG.

In this example, in the case of JIS standard, SCM material,
Good results were obtained by tempering at 630°C for about 60 minutes, but this tempering process requires only 8
Of course, the heating time and temperature may be adjusted according to the processing state.

Next, after the tempering process is finished, the workpiece 8 is taken out from the furnace 30 and heated to 30 to 60 mm using a vibrating barrel (not shown) or the like.
The material is subjected to vibration treatment for approximately 0 minutes to remove the paint adhering to its surface. In this case, since the processed material 8 and the coating material such as copper are not particularly strongly adhered to each other, the removal operation can be carried out efficiently even by using, for example, a wire brush.

Comparing the processing method of this example above with the conventional one, this example = paint application → quenching → oil cooling → tempering → paint removal Conventional example = quenching → oil cooling → tempering → As per Surface Research The features of this embodiment can be understood more clearly.

〔Effect of the invention〕

As described in 1-1, according to the present invention, the surface of the workpiece 8 is coated with a paint containing copper or the like as a main component in advance, without making the inside of the heating furnace l in a particularly non-oxidizing state. After that, the coating material is removed from the surface, and oxidation and decarburization are effectively prevented, and the heat treatment can be easily performed without losing brightness. Not only that, but the required installation cost can be reduced.Furthermore, since the coating agent is mainly composed of copper or copper alloy, it can be welded to the surface of the processed material 8 such as copper.
It becomes difficult to remove the paint, and there is no need to forcefully remove it using shot blasting or the like, and after the heat treatment as described above, light work such as wire brushing can be used to remove the paint from the surface of the workpiece 8. This is an epoch-making method that allows you to obtain a product that has high performance in one dimension and has brightness because there is no need to polish the surface by simply removing it.

In the examples, the present invention was explained using a batch type direct heating furnace using a burner as the heat source, but the heat source can be electric or other than the burner, and the present invention can also be applied to a continuous heat treatment method. Needless to say, it can be adopted.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view of a heating furnace for carrying out the method of the present invention, FIG. 2 is a sectional view taken along the line ■--■ in FIG. 1, and FIG. 3 is a longitudinal sectional front view of the tempering furnace. FIG. 4 shows a longitudinal sectional front view of a conventional salt bath furnace, and FIG. 5 shows a longitudinal sectional front view of the same conventional tempering furnace. 1...Direct heating furnace lO...Supporting means 2...
・Heating furnace body 12... Opening/closing means 6... Furnace lid 19... Weight 8... Processed material
30... Tempering furnace A... Container C... Processed material E... Inner cover F... Tempering furnace G... Heating coil Fig. 1 Fig. Fig.

Claims (1)

[Claims] Copper or copper alloy powder is mixed with a solvent to prepare a paste-like coating, and this coating is applied to the surface of the processed material such as steel to be heat treated, and then heat treatment such as quenching and tempering is performed in a heating furnace. , a non-oxidation heat treatment method for metals in which the paint is then removed from the surface of the processed material.