JPH0686622B2 - Oxidation-free heat treatment method for metals - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is capable of preventing oxidation and decarburization of a processed material such as steel and heat-treating it without making an oxygen-free atmosphere in a heating furnace. The present invention relates to a non-oxidizing heat treatment method for metals.

[Conventional technology]

Conventionally, heat treatment such as quenching and tempering is performed on the surface of a processed material such as steel material while preventing oxidation and decarburization, for example, by evacuating the heating furnace or injecting an inert gas. Heat-treated in an oxygen-free atmosphere,
As shown in FIG. 4, the processed material C is immersed in a salt bath agent B containing salts such as chlorides and bromides in a container A made of cast iron or steel and heat treated with a burner D or the like. 5 As shown in the figure, insert a protective atmosphere gas such as CO ₂ , argon, butane, etc. into the inner cover E that has been made non-oxidized and heat it in the tempering furnace F with the heating coil G to temper it. It is known that
("Handbook of Metals" edited by The Japan Institute of Metals, published in 1960, page 74-
(See page 94) Both require expensive equipment to maintain the inside of the furnace in a non-oxidized state, and unless the vacuum furnace is used, the surface of the processed material must be polished after the heat treatment. In this case, there is a defect that a product having the required glitter cannot be obtained.

[Means and Actions for Solving the Problems] In order to solve the above-mentioned defects, in the present invention, a coating material prepared by dissolving a preformed copper or copper alloy powder in a paste form with a solvent is applied to the surface of a processed material. After heat treatment in a heating furnace, the coating material is removed from the surface of the processed material to obtain a product with a desired hardness and a bright surface, and the surface of the processed material is polished after tempering. It is possible to obtain a product with high dimensional accuracy without the need for

〔Example〕

An embodiment for carrying out the method of the present invention will be described below with reference to FIGS.

The first and the second shown in the figures show a batch type direct heating furnace 1 in which a burner is used as a heating source in a circular-pid type, and a heating burner 3 is provided at the bottom of a cylindrical heating furnace body 2. and, a guide wall 5 for guiding the hot air 4 to the inner circumferential wall 2 along the _first furnace body 2, and disposed substantially arc at a predetermined gap inner wall 2 ₁ and on the hearth 2 _2, heating the suspension frame 7 which is suspended from the lower surface of the furnace lid 6 for opening and closing the top opening 2 ₃ of the furnace body 2, the holding frame 9 which can put the workpiece 8 by a required quantity, fixedly provided to the carrying means at appropriate stages the hooking rod 11 of the 10 with the disengageably has deployed an opening and closing means 12 of the furnace lid 6 separately to the furnace body 2, of the closing means 12, the outer periphery of the furnace body 2 projecting The support rod 13 is vertically fixed to the support rod 13 and the central portion is pivotally attached 15 to the top of the support rod 13. The tip of the lever rod 16 is pivotally attached 18 to the projecting frame 17 protruding from the upper surface of the furnace lid 6. On the other hand, at the rear end, a supporting rod 20 on which a required weight 19 is suspended is pivotally attached 21.

Further, FIG. 3 shows a tempering furnace 30 in which the carrying means 10 for the processed material 8 can be placed on the abutment 31 and the heating coil 32.
The air heated in (3) can be discharged from the exhaust stack 33.

Therefore, when heat treatment such as quenching, tempering, and annealing is performed on the processed material 8 made of steel, the powder made of preformed copper or copper alloy is used in a solvent such as boil oil, for example, copper alloy powder: solvent. = 3: 1 were mixed in a volume ratio to prepare a paste-like coating material, the coating agent was applied using a brush, such as the appropriate applicator to the surface of the workpiece 8, this in following the carrying means 10 It is placed on the holding frame 9, and the opening / closing means 12 is operated in a state where the latching rod 11 of the carrying means 10 is suspended on the suspension frame 7 of the furnace lid 6, and is inserted into the heating furnace main body 2. To close.

In this case, one of the features of the present embodiment is that it is not necessary to make the inside of the heating furnace 1 to be in an oxygen-free state by creating a special vacuum or injecting another inert gas.

In this state, the heating burner 3 is ignited and its hot air is blown into the hearth.
Increased while inducing the inner peripheral wall 2 along ₁ by the guide wall 5 from 2 ₂ to heat the furnace, depending on the size and material of the workpiece 8, for example, JIS standard, SK, SKS, S45C, SCM material such as In this case, quenching is performed by heating at 850 ° C for 15 minutes, or for SKD material at 1000 ° C to 1050 ° C for the same time.

In this case, since the surface thereof is covered with the coating agent made of copper or copper alloy, the surface of the processed material 8 is not likely to be oxidized, and decarburization can be safely prevented.

Next, the weight 19 is lowered and the furnace lid 6 is raised by the lever rod 16 to open it, and the processed material 8 is taken out from the heating furnace main body 2 together with the carrying means 10 suspended on the back surface thereof, and an oil tank (not shown). immersed within, and oil cooling process about 20 minutes at 40 ° C., the heating coil in a state of inserting the workpiece 8 with holding means 10 in the tempering furnace 30 of FIG. 3 in the following, it was placed on the abutment 31 32 tempering process.

In this case as well, since the surface of the processed material 8 is covered with the coating material that prevents oxidation and decarburization, it is not necessary to make the inside of the heating furnace 30 in a particularly non-oxidized state, and as shown in FIG. Inner cover E with processed material C in non-oxidizing atmosphere
There is no need to surround and heat-treat.

In this example, JIS standard, SCM material, 630 ℃
Although good results were obtained after tempering for about 60 minutes, it is needless to say that the tempering time may be adjusted by adjusting the heating time and the temperature according to the required processing state of the processed material 8. Is.

Next, after the tempering treatment is finished, the processed material 8 is taken out from the furnace 30 and is subjected to a vibration treatment for about 30 to 60 minutes by a vibrating barrel (not shown) or the like so that the coating material adhering to the surface can be removed. It was done. In this case, since the work material 8 and the coating material such as copper are not particularly strongly adhered to each other, the work of removing the work material 8 can be efficiently performed even if a wire brush or the like is used.

Comparing the treatment method of this example with a conventional method, the following is obtained in this example: coating application → quenching → oil cooling → tempering → removal of the conventional example = quenching → oil cooling → tempering → surface polishing. Yes, the features of this embodiment are more clearly understood.

〔The invention's effect〕

As described above, according to the present invention, without preserving the inside of the heating furnace 1 in a particularly non-oxidized state, the surface of the processed material 8 is preliminarily applied, and after the surface is coated with the coating material containing copper or the like as a main component. After heat-treating this, it is possible to heat-treat it simply by removing the coating agent from the surface, without oxidization and decarburization, and without losing the luster. In addition, the required equipment cost can be reduced, and further, since the coating material contains copper or a copper alloy as a main component, it is welded to the surface of the processed material 8 such as copper and its removal is difficult. Therefore, there is no need to remove this strongly by using shot blasting, and after the heat treatment as described above, the work material 8 is lightly worked by wire brushing or the like.
This is an epoch-making product that has a high dimensional accuracy and a glittering property, since it is not necessary to polish the surface, especially by removing the coating material from the surface.

In the examples, the present invention has been described with a batch type direct heating furnace using a burner as a heating source, but the heating source is not limited to electric and other burners, and the present invention is also applicable to a continuous heat treatment method. It goes without saying that it can be adopted.

[Brief description of drawings]

FIG. 1 is a vertical 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 II-II of FIG. 1, and FIG. 3 is a vertical sectional front view of a tempering furnace. The figure shows a conventional salt bath furnace,
FIG. 5 is a vertical sectional view of the conventional tempering furnace. 1 ...... Direct heating furnace, 10 ...... Supporting means 2 ...... Heating furnace main body, 12 ...... Opening / closing means 6 ...... Furnace lid, 19 ...... Weight 8 ...... Work material, 30 ...... Tempering furnace A ...... Container C …… Processed material E …… Inner cover F …… Tempering furnace G …… Heating coil

Claims (1)

[Claims] 1. A paste or coating material is prepared by mixing copper or copper alloy powder with a solvent, and the coating material is applied to the surface of a processed material such as a steel material to be heat treated and then quenched and tempered in a heating furnace. A non-oxidizing heat treatment method for metals, in which the coating material is removed from the surface of the processed material after the heat treatment such as.