JPH0718018B2 - Antioxidant for titanium and titanium alloy and method for preventing titanium and titanium alloy from oxidation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is an antioxidant and an antioxidant method suitable for preventing the oxidation caused by heating titanium and titanium alloys in a general oxidizing atmosphere furnace. .

(Prior Art) It is possible to prevent oxidation caused by heating titanium and titanium alloy by heating in an inert gas atmosphere or in vacuum, but the productivity is low and the cost is high.

On the other hand, for the purpose of making titanium and titanium alloys usable at high temperature, as a method for imparting oxidation resistance to their surfaces, aluminizing, silicide coating, aluminum plating, nickel plating, platinum plating, aluminum spraying, nickel-chromium spraying Although gold ion plating, platinum ion plating, tungsten ion plating, etc. have been studied, they are rarely used in actual production sites because they have extremely low productivity and high cost.

(Problems to be Solved by the Invention) When titanium is heated using a general heating furnace in an oxidizing atmosphere, titanium is oxidized to generate rutile scale, and oxygen is diffused into metallic titanium. Then, a very hard layer is formed on the surface. This hard layer is used for rough skin,
It must be removed because it causes surface defects such as baldness, but it is impossible to completely remove it using a shot blasting and descaling device. Therefore forging,
For the slab manufactured in the agglomeration process, the entire surface is ground to remove this hard layer, and in addition, in the heating before hot rolling, the heating temperature, heating time, etc. are controlled to form this hard layer. The current situation is to suppress it.

Although the above-mentioned conventional technique can prevent the oxidation of titanium, it is not suitable for application to a large-scale production process using titanium ingots, titanium slabs, and the like.

The above circumstances also apply to titanium alloys.

The present invention provides an antioxidant and an antioxidant method suitable for titanium and titanium alloy lumps and titanium and titanium alloy slabs, whereby the entire surface grinding in the slab adjusting step is omitted, and a heat treatment is performed. The pre-deposition heating conditions are greatly expanded.

Here, titanium alloy is Ti-5Al-2.5Sn, Ti-6Al-4V, T
i-6Al-6V-2Sn, Ti-15V-3Cr-3Al-3Sn, etc.

(Means for Solving Problems) In the forging, slab or hot rolling process of titanium and a titanium alloy, the present invention is performed on the surface of titanium and a titanium alloy slab or titanium and a titanium alloy slab prior to heating. It is possible to prevent the oxidation of titanium and titanium alloys by a method having an extremely high productivity by applying an antioxidant containing powder as a main component using a brush or a spray.

(Function) Prior to heating titanium and titanium alloy lumps or titanium and titanium alloy slabs, aluminum powder having a grain size of 100 mesh or less, preferably scaly aluminum powder is 45 to 75 wt.
%, The balance consisting of resin For the titanium and titanium alloy lumps that require heating before slab rolling at 900 ° C to 1200 ° C, an antioxidant mixed with 100 parts by weight of solvent to 40 to 200 parts by weight is used. , Aluminum powder is 30 to 300 g / m ² , and for titanium and titanium alloy slabs that require pre-hot rolling heating at 800 to 1000 ° C, aluminum powder is applied to 5 to 130 g / m ² . Then, the above-mentioned antioxidant is applied, and after naturally drying, it is placed in a heating furnace.

Here, the reason why the aluminum powder is 100 mesh or less is that the ordinary brush coating or spray coating becomes difficult if the aluminum powder is more than 100 mesh. The above contents are shown in Table 1.

Further, the scale-like aluminum powder is preferable because it is easy to apply and the resin is difficult to peel off after decomposition at high temperature. Regarding the antioxidant effect of the chemical composition of the aluminum powder, the scale-like aluminum powder manufactured by the stamp method from JIS standard 1070, IN30, 3003 aluminum foil and aluminum alloy foil, and the atomizing method from aluminum with a purity of 99.0% or more are used. The produced spherical aluminum powder showed the same antioxidant effect as the spherical aluminum powder produced by the atomization method from aluminum having a purity of 99.9% or more.

Here, the aluminum powder is 45 to 75 wt% because it is 45 wt%.
If the amount is less than 50%, the residual resin decomposes at a high temperature and then the coating film becomes defective, and the oxidation prevention becomes incomplete. It is easy to peel after drying. The above contents are shown in FIG.

Here, as the resin, a phenol resin, an alkyd resin, an epoxy resin, and a vinyl resin, which are excellent in adhesiveness with a metal and are air-dried, are suitable.

The solvent 40 to 200 parts by weight means that the viscosity is large when it is less than 40 parts, and conversely when it is more than 200 parts, the viscosity is small, and both are brushed.
This is because spray painting becomes difficult. The solvent may be aromatic hydrocarbon, aliphatic hydrocarbon or the like.

This is because if the lower limit of the amount to be applied prior to the heating before slab rolling and the heating before hot rolling is less than this, the oxidation prevention is incomplete, and the upper limit is unnecessary. In particular, if the upper limit of the amount applied before heating before hot rolling is exceeded, the titanium-aluminum intermetallic compound layer described later will be formed to a thickness greater than that required for oxidation prevention, and this will cause the occurrence of surface defects. The proper coating amount according to the temperature is shown in FIG. This figure applies to titanium and titanium alloys.

Next, when the temperature is raised in the heating furnace, the resin decomposes and disappears as a gas, but the aluminum powder continues to adhere to the titanium surface and melts when heated to 660 ° C or higher, and the continuous melting on the titanium surface. It forms a film and subsequently reacts with titanium to form a titanium-aluminum intermetallic compound. This layer has extremely excellent resistance to oxidation as compared with titanium, so that oxidation is suppressed and diffusion of oxygen into titanium metal is also significantly suppressed. In addition, when titanium is heated in an atmosphere containing H ₂ O, hydrogen is absorbed in the titanium, but when the antioxidant of the present invention is applied and heated, the amount of absorbed hydrogen is reduced. I also confirmed that.

Thus, when the antioxidant of the present invention is applied and heated according to the antioxidant method of the present invention, a hard oxygen solid solution layer that causes surface defects is not formed, and the titanium-aluminum intermetallic compound layer is sufficiently thin. Therefore, it does not cause surface defects. In addition, there is a fine alumina layer on the intermetallic compound layer, which has an effect of suppressing the surface roughness by performing good rolling. Further, it was confirmed that the titanium-aluminum intermetallic compound remaining after hot rolling can be removed by pickling.

(Example 1) 63 wt% of scaly aluminum powder having a particle size of 200 mesh or less,
An alkyd resin consisting of 37 wt% 100 parts by weight and 140 parts by weight of mineral spirit were mixed with an antioxidant, and sprayed onto C / PII type titanium so as to be coated with aluminum powder at 20 g / m ² and 30 g / m ² After that, let it air dry, 20g
830 as the equivalent of hot rolling for the product coated / m ²
The test piece was kept in the atmosphere at 4 ° C. for 4 hours, and the one coated with 30 g / m ² was heated at 950 ° C. for 4 hours in the air as lump-block equivalent heating. As a comparative material, titanium to which the antioxidant according to the present invention was not applied was heated under the same conditions as the applied material and subjected to the test.

The cross-sectional hardness distribution result of the hot rolled equivalent heating material is shown in FIG. 3, and the cross sectional hardness distribution of the lump equivalent heating material is shown in FIG. As shown in the figure
The hardness of 200 Hv or more is 0 μm for the hot rolled equivalent heating material and 65 μm for the uncoated material, and 0 μm for the lump equivalent heating material and 150 μm for the uncoated material. And showed a remarkable suppressing effect on the formation of the cured layer.

Next, in order to confirm these effects as the effect of reducing surface defects, a titanium plate was prepared by eight processes shown in Table 2, and the surface condition was visually observed after shot blasting. The C process uses the antioxidant of the present invention for pre-agglomeration heating and pre-hot rolling heating according to the antioxidant method of the present invention, while the F process is a conventional process. In comparison with this, in the case of the present invention, a good surface texture can be obtained with a high yield without going through a grinding process.

Here, the test material is 100t x 100w x 20 from the C / PI type ingot.
A cutout of 0 Lmm ³ was used. The amount of antioxidant used before slabbing was 70 g / m ² of aluminum powder. Slump rolling schedule is 100 → 80 → 60 → 40 → 30mm
Is. Grinding amount is about 1mm on one side, yield is about 0.6%
Fell. The amount of antioxidant used before hot rolling was 10 g / m ² of aluminum powder.

(Example 2) 63 wt% of scaly aluminum powder having a particle size of 200 mesh or less,
Alkyd resin 37 wt% 100 parts by weight of mineral spirit 140 parts by weight of anti-oxidant by brush coating, C / PII type titanium, Ti-5Al-2.5Sn, Ti-6Al-4V, Ti
-6Al-6V-2Sn, each having a thickness of 10mm of the Ti-15V-3Cr-3Al- 3Sn, was coated so as to apply 50 g / m ² and 150 g / m ² of aluminum powder, air-dried, 50 g / Those coated with m ² were held at 950 ° C. for 4 hours in the air, and those coated with 150 g / m ² were held at 1150 ° C. for 4 hours in the atmosphere. The thickness reduction thickness of the coating material of the antioxidant of the present invention and that without coating were compared, and the results are shown in Table 3. Here, the thickness reduction thickness is the sum of the thickness reduction due to scale loss and the thickness of the hardened layer formed by oxygen diffusion. Here, the cured layer was a portion having a hardness of 500 Hv or higher. As you can see from this table, not only pure titanium but also α type, α + β
It is effective for 1-type and β-type titanium alloys and has a thickness reduction of about 1/10.
It can be seen that it can be reduced to ~ 1/20.

(Effects of the Invention) As described above, according to the antioxidant of the present invention and the antioxidant method using the same, it is possible to oxidize titanium and titanium alloys with high productivity by an extremely simple method such as brush coating or spray coating. As a result, since a hard layer due to scale and oxygen diffusion is not formed, wide heating conditions can be adopted in the forging and agglomeration steps, the slab grinding step can be omitted, and the yield is improved. In the hot rolling step, similarly, a wide range of heating conditions can be adopted, and a hot rolled sheet with a good surface texture can be manufactured.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the ratio of aluminum powder to resin and the antioxidation area and the coating film adhesion at room temperature,
FIG. 2 is a diagram showing an appropriate amount of aluminum powder applied according to the heating temperature, and FIG. 3 is a diagram showing depth hardness distributions of the antioxidant coated material of the present invention and the uncoated material in heating equivalent to hot rolling.
FIG. 4 is a view showing depth hardness distributions of the antioxidant-coated material and the non-coated material in heating corresponding to the lump.

Claims (5)

[Claims] 1. Oxidation of titanium and titanium alloys comprising a mixture of aluminum powder having a particle size of 100 mesh or less of 45 wt% to 75 wt% and the balance of 100 parts by weight of resin and 40 to 200 parts by weight of solvent. Preventive agent. [Claim 2] Aluminum powder is JIS standard 1070, IN30, 300
The antioxidant according to claim 1, which is a scaly aluminum powder having a grain size of 100 mesh or less, which is produced from the aluminum foil and aluminum alloy foil of 3 by a stamping method. 3. An aluminum powder having a particle size of 200 produced by an atomizing method from aluminum having a purity of 99.0% or more.
The antioxidant according to claim 1, which is a spherical aluminum powder having a mesh or less. 4. The resin is a phenol resin, an alkyd resin,
The antioxidant according to claim 1, which is an epoxy resin or a vinyl resin. 5. Titanium and titanium alloys are forged, agglomerated or
In the process of manufacturing by hot rolling or the like, prior to heating, the titanium lump or titanium slab surface has a grain size of 10
45-75 wt% aluminum powder of 0 mesh or less, the balance consisting of resin 100 parts by weight of the antioxidant compounded with 40-200 parts by weight of solvent, forging, in the agglomeration process, aluminum powder, 30 ~ 300 g / m ² , in the hot rolling process,
Apply so that the aluminum powder is 5 to 130 g / m ² ,
A method for preventing oxidation of titanium and titanium alloys, which comprises heating and rolling.