JPS60255962A - Heat treating apparatus - Google Patents

Abstract

PURPOSE:To suppress the dezincing reaction from an alloy and to improve the productivity by providing a zinc vapor analyzer, a zinc vapor controller, etc., and maintaining at all times the zinc vapor pressure in a furnace for heat treating the zinc alloy to the saturated state. CONSTITUTION:A heat treating apparatus consists of the zinc vapor analyzer 4 for measurig the zinc vapor pressure of the atmosphere in the heat treating furnace 10, the zinc vapor controller 7, a zinc vapor supplying source 8, and a protecting gas supplying source 1. Said controller 7 controls the zinc vapor quantity supplied into the furnace 10 by he output of said analyzer 4. Said source 1 supplies the gas of a fixed pressure for preventing oxidation of the zinc in the furnace 10 through a pressure control valve 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a heat treatment method for preventing the so-called dezincification reaction in which zinc in brass evaporates during heat treatment.

[Prior Art] In general, WI base metal materials are provided with predetermined mechanical properties or by adjusting the grain size to improve mechanical properties such as hardness and elasticity, material formability, fatigue properties, and tendency to crack during time. etc. are greatly influenced by the conditions of the heat treatment, so various heat treatments are used.

However, when an alloy containing a large amount of zinc, such as a brass material, is heated above about 400 to 450 DEG C. and subjected to C heat treatment, the surface of the material changes to a copper color, that is, becomes Redsta 1n. The red stain is based on the fact that the rate of evaporation of zinc from the surface of the material is greater than the rate of diffusion inside the material, and as for river sand, the characteristic diagram in FIG. 2 shows this.

Figure 2 shows the zinc electrical distribution diagram in the sample cross section when 70/30 brass is dezincified at 800°C.
Vol. 14, No. 6, Isao Ito, "Dezincification Phenomenon of Brass"). In the figure, (a) the processing time is 1 and the processing time is 4.
Distribution state over time, (b) between 1 and L 8v1, (C) i. tl: between 2R, (d) i, l 1
6 1ks, and (e) shows the distribution state after 20 hours. It can be seen that as dezincing progresses over time, the surface zinc concentration decreases as indicated by the arrow in Figure 2. In addition, it can be seen that the diffusion rate of brass dezincification is high in a region from the surface force to a depth of about 20 μm, and the movement of zinc occurs at a rate close to the evaporation rate. The area is u
It is generally said that when an element of P is added to brass of P, it has the effect of promoting dezincification, although the degree of addition varies depending on the type of element.

However, when the additive element is M, t is 500
There is also a paper (in the same journal) that points out that the dezincing effect disappears only when the temperature is below ℃, but it requires the effort of adding M to the material, and furthermore, it is difficult to put it into practical use due to the change in material properties and mechanical strength due to the addition of M. I had the above problem.

Therefore, it is now common practice to heat-treat the brass surface in a slightly oxidizing gas to create a dense oxide film on the brass surface, prevent the evaporation of zinc, and then remove the oxide film by pickling after cooling. It is.

[Problem to be Solved by the Invention 1] However, in this type of method for forming an oxide film, a step of forming an oxide film on the brass surface and a step of removing the oxide film are added. Two steps, a forming step and an oxide film removal step, were added, which resulted in unfavorable productivity.

[Problem of the Invention] Therefore, an object of the present invention is to provide a method for suppressing the dezincification reaction by heat treatment without changing the structure of the brass material.

[Means for Solving the Problems 1] The heat treatment method and heat treatment apparatus for preventing the dezincification reaction of the present invention include a zinc vapor analyzer that measures the vapor pressure of zinc in the furnace atmosphere; Obtain output and control zinc vapor supply amount DI+-! a zinc vapor controller, a zinc vapor source for supplying zinc vapor into the furnace, and a gas at a constant pressure, such as H
2 or a protective gas supply source that supplies CO, or a pressure ratio of the protective gas supply source and the atmosphere in the furnace pH2/pl-120
, or analysis to detect either pCO/pCO2 8
1, the above pl-12/pl-120, or pCO/[
) It consists of a protective gas controller or a gas concentration controller that obtains the output of the CO2 analyzer and determines the color of the protective gas supplied into the furnace.

[Function] A protective gas such as CO+CO2+N2 or HO+N2 is added to the furnace atmosphere to prevent non-oxidation heat treatment of the brass.
is supplied to maintain the gloss of the surface of the material before heating, and to create an atmosphere at an arbitrary constant pressure that facilitates dezincification and galvanization.

The evaporation of zinc from brass is difficult if the zinc vapor pressure in the surrounding area is saturated. The zinc vapor content is measured, and the difference between the value above the saturated zinc vapor pressure set in advance in the vapor pressure setting unit and the output of the zinc vapor analyzer is detected, and the zinc vapor content is measured according to the difference. Control the valve of the steam supply source to supply insufficient steam into the furnace.

Therefore, the inside of the furnace is always in a saturated vapor pressure state of zinc and lead, and heat treatment can be performed while preventing dezincification.

The means for keeping the pressure constant is a method of supplying a pressure equivalent to the reduced pressure when the pressure in the furnace is reduced by a pressure regulating valve, or a method of controlling the supply amount of protective gas with a pressure gauge installed in the furnace. Any method such as control may be used. Of course, other methods of keeping the pressure constant may also be used.

[Embodiments of the invention] Next, embodiments of the present invention will be described using figures.

FIG. 1 is an explanatory diagram showing a first embodiment of the present invention. In the figure, a furnace 10 and a stand 12 disposed in a class 10 have a well-known structure, and the furnace 10 has a humidity detector 1 such as a thermocouple.
Based on the temperature detected by 4, the current of the heater 11 is adjusted to the temperature set by the temperature setting unit 16.
A specific furnace temperature is set by a temperature controller 17 that controls a current control section 15. The temperature controller 17 of this scale is also a well-known furnace temperature control vi.
location can be used. Furnace 10 for carrying out the invention
This means that the well-known heat treatment furnace technology not described in this embodiment can be used for the structure and its temperature controller 17.

The protective gas supply source 1 contains CO or H2 gas that prevents oxidation of the surface of the brass material 13 to be heat treated, and is a pressure horn stone supply source supplied to the heat treatment furnace. Specifically, CO+C as a protective gas.

-1-N or H+HO+N2 gas is used 2 2
2 2 will be. The CO+Co2+N2 or i, tH2+l-1
The 200 N2 gas is supplied to the furnace 10 through the pressure regulating valve 2, so that the atmosphere inside the heat treatment furnace is constantly filled with protective gas.

Next, the operation of the brass heat treatment method of this embodiment will be explained.

A protective gas is introduced from the protective gas supply source 1 into the heat treatment furnace 10, and while the furnace is in a protective gas atmosphere, the heat treatment temperature of the brass material 13 is increased, the output of the detector 3 is obtained, and the zinc vapor analyzer is 4 to open the zinc gas content. Since the moisture-zinc vapor pressure characteristic of 4J under an arbitrary pressure is set in advance in the zinc vapor pressure setting section 6, the selected zinc saturated vapor pressure is controlled by the output of the temperature detector 14. There, the difference between the two is taken and the butterfly valve 9 is outputted to the butterfly valve 9 via a driving means such as a motor or the like.
Zinc vapor is supplied from the zinc vapor supply source 8 to the furnace 10 by controlling the opening degree of the zinc vapor supply source 8 . That is, with respect to the value of zinc vapor obtained in the zinc vapor analysis 44, the zinc vapor=1 controller 7 consisting of the setting section 6 and the vapor pressure control section 5 always adjusts the zinc vapor pressure in the furnace atmosphere to saturated vapor. set to pressure.

This example uses a zinc vapor analyzer to detect the presence of zinc in Class 10, such as protective gas supply '&1, which supplies cold gas to prevent zinc oxidation. , the zinc vapor controller 7 controls the amount of zinc vapor supplied from the zinc vapor supply source 8 into the heat treatment furnace 10, so brass can always be heat treated under the saturated vapor pressure of zinc, and the material Dezincing from brass can be kept to a minimum.

FIG. 3 is an explanatory diagram showing a second embodiment of the present invention.

Only the phase 3i of the first embodiment of the invention shown in FIG. 1 will be described. In the first embodiment shown in FIG. 1, the pressure regulating valve is
However, in this embodiment, the pressure is controlled by a pressure control system. In the figure, the same symbols 1 and 3 to 17 as in FIG. 1 are the same as those used in the first embodiment.

The pressure inside the heat treatment furnace 10 is controlled by a Bourdon tube, a diaphragm,
Furnace pressure needle 21 having a pressure detector 20 made of bellows etc.
The output of the furnace pressure needle 21 is the pressure control 0-524.
The furnace pressure control unit 22 obtains the difference between the set pressure of the furnace pressure control unit 22 and the furnace pressure setting unit 23 that is set in advance, and -
The opening degree of the valve 25 is controlled using a well-known driving means according to the output of the furnace pressure control section 22, and the protective gas supply source 1 is used to prevent zinc oxidation in class 10 H24-1120
' Supply a protective gas such as N2 or CO+COl-N2 gas.

Therefore, in this embodiment, since the pressure in the furnace, which is a parameter of the saturated zinc vapor pressure, can be controlled to be constant at all times, the amount of dezincing can be reduced, and the v1sx material 13
It can prevent surface oxidation.

Further, FIG. 4 is an explanatory diagram showing a third embodiment of the present invention.

Only the differences from the first and third embodiments will be described. In the first and second embodiments shown in FIGS. 1 and 3, the supply of protective gas was entrusted to the pressure inside the heat treatment furnace 10, but in the third embodiment, the supply of protective gas was The value of p) 12/pH 20 or pCO/pCO2, which is the purpose of supply, is subjected to a base e ill'm. In addition, in the figure, f! The same symbols 1 and 3 to 17 as in FIG. 1 are the first embodiment, and 25 is the same as that used in the second embodiment.

The gas detection unit 30 detects the gas within Class 10,
A gas analyzer 31 analyzes gases within class 10. The above gas analysis is to analyze the proportion of CO or N2 that affects the oxidation of zinc. When CO+CO2+N2 is used as a protective gas to prevent zinc oxidation, pCO/
pCO2, when H + H20 + N2 is used as a protective gas, pto12
/pH20 is detected.

The output of the gas analyzer 31 is compared with the oxidation prevention set value set in advance in the gas m degree setting part 33 by the gas 11 degree control section 32, and the state of the protective gas within Class 10 is determined to be higher than the oxidation prevention set value. Based on the difference between the two, the opening degree of the valve 25 is adjusted using a well-known valve driving means so as to maintain the position. Note that the gas concentration setting section 33 and the gas concentration control section 32
constitutes the protective gas concentration controller 34.

Therefore, according to this embodiment, by detecting the υj mixture containing CO and N2, which are directly involved in preventing oxidation of zinc, the relationship between the pressure of the protective gas and the ability to prevent oxidation can be obtained. The internal atmosphere can be maintained under the condition of zinc oxidation prevention.

[Effects of the Invention] As described above, the present invention creates a protective gas atmosphere in a heat treatment furnace that prevents oxidation of zinc supplied from a protective gas supply source, and also provides a zinc vapor analyzer that measures the vapor pressure of zinc. The amount of zinc vapor supplied from the zinc vapor source into the furnace is determined by the output of i! By controlling the zinc vapor, the inside of the furnace is always kept in a state of saturated zinc vapor pressure, so heat treatment can be carried out in a state where dezincification is prevented without adding other processing steps, Good productivity.

In addition, since the present invention suppresses the dezincification reaction and performs heat treatment, the heat treatment can be performed without changing the structure of the material, and since dezincification does not create pores or cracks in the crystals of the material, it increases mechanical strength. It has no effect on the melon.

[Brief explanation of drawings]

FIG. 1 shows a first embodiment of the present invention. i Explanatory diagram, Figure 2 shows a zinc concentration distribution diagram in a cross section of a sample after dezincing treatment, and Figure 3 shows a second embodiment of the present invention. I explanatory diagram, 4th
The figure is an explanatory diagram showing a third embodiment of the present invention. In the figure, 1... protective gas supply source, 2... pressure regulating valve, 4... zinc vapor analyzer, 7... zinc vapor controller, 8... zinc vapor supply source, 10... heat treatment Furnace, 21... Furnace pressure needle, 24... Protective gas controller, 31... Gas analysis S1. 34...Gas concentration controller. In addition, in the figures, the same reference numerals and the same symbols indicate the same or equivalent parts. Patent applicant: Daido Steel Co., Ltd. Agent: Takehisa Higuchi

Claims (7)

[Claims] (1) a zinc vapor analyzer that measures the vapor pressure of zinc in the atmosphere inside the heat treatment furnace; a zinc vapor controller that controls a zinc vapor supply source that supplies zinc vapor into the furnace based on the output of the zinc vapor analyzer; It is characterized by comprising a zinc vapor supply source that generates the zinc vapor to be supplied, and a protective gas supply source that supplies gas at a constant pressure to prevent oxidation of zinc into the furnace via a pressure regulating valve. Heat treatment equipment that prevents dezincification reactions. (2) a zinc vapor analyzer that opens the zinc vapor pressure in the atmosphere inside the heat treatment furnace; and a zinc vapor controller that controls the zinc vapor supply m that supplies zinc vapor into the furnace based on the output of the zinc vapor analyzer. , a zinc vapor supply source that generates the zinc vapor to be supplied; a furnace pressure gauge that measures the pressure in the furnace; and a protective gas supply that supplies protective gas to prevent zinc oxidation into the furnace based on the output of the furnace pressure gauge. Control ω tMI
A heat treatment apparatus for preventing a dezincing reaction, comprising a protective gas controller that generates the protective gas, and a protective gas supply source that generates the protective gas to be supplied. (3) a zinc vapor analyzer that measures the vapor pressure of zinc in the atmosphere inside the heat treatment furnace; and a zinc vapor controller that controls the supply of zinc vapor to supply zinc vapor into the furnace based on the output of the zinc vapor analyzer. , a zinc vapor supply source that generates the supplied zinc vapor, a gas analyzer that analyzes gas in the atmosphere in the furnace, and a protection that prevents oxidation of zinc into the furnace by the output of the gas analyzer. A heat treatment apparatus for preventing a dezincing reaction, comprising a gas concentration controller that controls the amount of protective gas supplied, and a protective gas supply source that generates the protective gas. (4) A heat treatment apparatus for preventing the dezincing reaction described in the patent or item 2 or item 3, characterized in that the protective gas is C0I-CO2+N2. (5) A heat treatment apparatus for preventing the dezincing reaction as described in the patent or item 2 or 3, characterized in that the retention ratio is 12+H2o+N2. (6) The gas analyzer is connected to the pressure ratio pCO of the furnace atmosphere.
5. The heat treatment apparatus for preventing the dezincification reaction according to claim 4, characterized in that the analysis is performed for /pCO2. (7) The gas analyzer is connected to the pressure ratio pH2 of the furnace atmosphere.
The heat treatment apparatus for preventing the dezincing reaction according to claim 5, characterized in that the analysis is carried out at pH 20.