JPS6028884B2 - Method for manufacturing heat-resistant tooth-shaped cutter bits - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a heat resistant tooth cutter bit.

As shown in Fig. 1, the conventional tooth-shaped cutter bit for geological excavation uses structural alloy steel for the main body 2, which is heat-treated by quenching and firing, and then carburized on the inner and outer surfaces. It has carburized hardened layers 2A and 2B, and although it serves the purpose to some extent for normal geological excavation,
When excavating 20,000 or more high-temperature strata such as in geothermal development, the tensile strength decreases, as well as the rupture strength and creep strength, which has the disadvantage of significantly reducing the excavation performance.

An object of the present invention is to overcome the above-mentioned conventional drawbacks of tooth-shaped cutter bits and to provide a tooth-shaped cutter bit that has high heat-resistant strength, high temperature wear resistance, and excellent excavation performance at a low manufacturing cost.

The gist of the present invention is as follows.

That is, a step of manufacturing a cutter bit material by casting molten precipitation-hardening heat-resistant steel into a mold created by the lost wax method, a step of solution-treating the material, and a nitriding treatment of the solution-treated material. This is a method for manufacturing a heat-resistant tooth-shaped cutter bit, comprising the steps of: and aging treatment at the same time. That is, the heat-resistant steel used for casting the cutter bit material in the present invention may be precipitation hardening type, such as martensitic steel such as 17-4 pH, semi-austenitic steel such as 17-7 pH, and 17-1 Misaki steel. It may be any type of austenitic precipitation hardening heat resistant steel. Thereafter, in order to obtain a supersaturated solid port, a solution treatment is performed by heating and rapidly cooling at a temperature of 1000 to 1150 oC.

Furthermore, after the solution treatment, an extremely hard nitrided layer is formed on the inner and outer surfaces of the cutter bit material by performing a nitriding treatment in which the cutter bit material is heated for several hours in a temperature range of 500 to 600 oo in an NH3 gas stream. The heating in this temperature range also serves as an aging treatment for the heat-resistant steel, and it has been found that by this treatment, a hardened layer with a Vickers hardness of HMv (300 mm) or more of 1100 or more can be obtained on the inner and outer surfaces. .
That is, as shown in FIG. 2, the cutter bit body 4 is made of precipitation-hardening heat-resistant steel and has a nitrided layer on the hardened layers 4A and 4B on the inner and outer surfaces, and is subjected to aging treatment at the same time as the nitriding treatment. A feature of the present invention is that age hardening provides excellent strength and strength as well as ballability, and that the work process is simplified to reduce manufacturing costs.

Example 1 A cutter bit material as shown in FIG. 2 was produced by pouring molten precipitation hardening heat resistant steel as shown in Table 1 into a mold made by the lost wax method.

Table 1 First, the cutter bit material is 1050mm.
The material was heated to a temperature of 100°C and then subjected to a solution treatment of water quenching, and then the material was subjected to a nitriding treatment at 570 oo for two periods and an aging treatment at the same time, followed by air cooling.

The rupture stress and creep stress at 48000 after treatment are shown in Table 2.

Table 2 Example 2 A cutter bit material made of the same precipitation-hardening heat-resistant steel as in Example 1 was manufactured, and after solution treatment by the same method, nitriding treatment and aging treatment were performed simultaneously for 570,002 hours.

Regarding the depth from the surface to the 2.0 side of the thus obtained cutter bit according to the present invention and the nitrided product of the conventional structural alloy steel SNCM-29 material, both as-is and after being heat-treated at 40,000°C for 1 hour. The results of hardness measurements are shown in FIGS. 3 and 4, respectively. In other words, as shown in Figure 3, the maximum hardness during nitriding is Hvl12.
0, which is 1.3 times harder than Hv880 of SNCM-29 material. In addition, the internal hardness is Hv370-380, whereas the SNCM-25 material, which is a structural alloy steel, is Hv270.
~280, and the material of the present invention exhibits 1.4 times the hardness. Further, as shown in FIG. 4, the hardness distribution after heating at 400°C for 1 hour showed no decrease in hardness compared to room temperature.

Therefore, by simultaneously subjecting precipitation hardening heat-resistant steel to solution treatment, aging, and nitriding, the 1.3
It is possible to have double the surface hardness and 1.2 times the internal hardness, and no decrease in hardness was observed even after heating to 40,000 °C. The above experiment confirmed that the cutter bit according to the present invention can exhibit excellent digging performance even in a high-temperature working environment. Example 3 A cutter bit material was manufactured using the same steel type and the same treatment as in Examples 1 and 2, and after solution treatment, nitriding treatment and aging treatment were performed at 52,000°C, 570°C, and 620q, respectively.
Fig. 5 shows the results of measuring the tensile strength, hardness, and impact value after aging for 2 hours.

It is natural that a heat-resistant cutter bit needs to have excellent not only hardness but also tensile strength and impact value based on the conditions of its use. As is clear from Figure 5, in the case of precipitation hardening heat-resistant steels as listed in Table 1, when nitriding and aging are simultaneously performed at 570°C for 2 hours after solution treatment, strength, hardness, and impact values are It has been found that it is possible to combine the three factors to the maximum extent possible.

Example 4 The hardness and impact value of the surface and interior of cutter bit materials made of precipitation-hardened heat-resistant steel shown in Table 1 were compared by treating them using the following three different methods.

■ If nitriding is simply performed at 570°C for 2 hours without solution treatment, {B] material is solution treated at 1050 oo and then aged at the same time as nitriding at 570°C for 2 hours. If processed, the material will be 1050 oo
In the case where solution treatment was performed at 570 °C for 4 hours without nitriding treatment.

As shown in Figure 6, the results of this comparative test show that the sail has a high surface hardness, but the internal hardness is about 3004V, which is slightly inferior to that of the 0.2 skin, which was not subjected to the nitriding treatment. As a matter of course, the surface hardness of 'B)' is much lower, showing an almost uniform hardness of 380 Kv both on the surface and inside, whereas 'B)' has a surface hardness of 1050 HMv due to the treatment of the present invention.
Not only did the internal hardness reach approximately 40, it was found to be the most excellent treatment for cutter bit hardness.

Furthermore, the results of comparing the impact values of the treated materials after the above treatment are shown in FIG. 7.

In other words, the impact value of the material without solution treatment was extremely low, around 1.0 k9 m/force, whereas the impact value of the material without solution treatment was extremely low, at around 1.0 k9 m/force, whereas in the case of 'C', which was subjected to solution treatment and only aging treatment without solution treatment.
had the highest impact value, reaching 5.0k9 m/pillow. On the other hand, it was found that the treated material according to the present invention had a toughness that was almost comparable, although the impact value was slightly lower than that of . As mentioned above, it is necessary for the cutter bit material to have a combination of strength, hardness, and graininess.
As a treatment method that combines these three, it has been found that the most excellent method in terms of properties and workability is to first perform solution treatment and then perform nitriding treatment and aging treatment simultaneously.

Example 5 Precipitation hardening type heat-resistant steels listed in Table 1 of Example 1 and subordinate structural alloy steels SNCM-25 and SUS304 were combined into 105
After performing solution treatment by heating to 0qo and then cooling, 5
2000, 8000, and 10
A corrosion test for sulfide corrosion was conducted by immersing the sample in S04 at a 5% by weight ratio of 0qo.

The results of the corrosion test are shown in Table 3. Table 3 As is clear from Table 3, the precipitation-hardened heat-resistant steel treated according to the present invention exhibits the strongest sulfuric acid corrosion resistance and is excellent as a material for cutter bits used in sulfide corrosive environments such as oil wells. It was revealed that it exhibits corrosive properties.

Example 6 Precipitation hardening heat-resistant steel having the composition shown in Table 1 of Example 1 was used,
A cutter bit material was manufactured by the same process, and after solution treatment, nitriding treatment was performed at 570 qo for 4 heating periods, and aging treatment was simultaneously performed for 2 heating hours to form hardened layers 4A and 4B on the surface and inside as shown in Fig. 2. .

A high-temperature drilling comparison test was conducted between the cutter bit thus manufactured and a conventional product made of carburized structural alloy steel.

The test conditions are as follows. Bit size 71'2 inch cutter bit drilling machine Tone Boring Co., Ltd.
W-Next bit rotation speed: 8pm Excavation temperature: 300pm Object to be excavated: Densbur FC-20 Supply pressure: 4-force The excavation length when the supply pressure was increased from 4t to 7t every hour is as shown in Table 4. be.

Table 4 This test was conducted using cast iron FC-2, which has significantly worse excavability than rock.
After excavating for 1 hour at 0, the supply pressure was increased in lt increments for testing, and compared to the conventional product made by the carburizing hardening method of structural alloy steel, the product made of heat-resistant steel having the composition shown in Table 1 above was tested. It has been found that a cutter bit in which the cutter bit material is subjected to lacquer treatment, followed by nitriding treatment and aging treatment simultaneously according to the present invention has significantly superior performance.

In other words, when using the conventional product, the bearing rattle increased due to the maximum supply pressure of 7 tons, and the digging length was actually reduced compared to when using the pressure supply technique due to the large amount of wear on the bit.
In the case of the product of the present invention, there is no abnormality in the bearing, there is only slight wear on the bit, and the digging length tends to increase with the supply pressure, and the digging length is 140% or more under the supply pressure compared to the conventional product. demonstrated its performance. The present invention not only changes the hardening of structural alloy steel, which was conventionally used as a material for cutter bits, by carburizing, but also hardens precipitation-hardened heat-resistant steel by nitriding. By using the unique processing method of simultaneous processing, we were able to achieve the following effects as evident in each of the above embodiments.

{i} Not only does it exhibit excellent properties in terms of strength, toughness, and hardness at room temperature, but even in high-temperature drilling of 200 oo or more, it does not suffer from any decrease in tensile strength or hardness, nor does it suffer from a decrease in plateau strength or creep strength. This shows the excavation performance.

[o} Shows no susceptibility to stress corrosion cracking or sulfide corrosion even at temperatures above 200 ooohes, and has excellent wear resistance.

Since nitriding treatment and aging treatment can be performed simultaneously, the manufacturing process can be simplified and costs can be reduced.

6 Due to the above-mentioned excellent performance, it can be used in a wide range of applications under heavy use conditions such as geothermal development and high-temperature geological excavation.

[Brief explanation of the drawing]

Fig. 1 is a schematic partial cross-sectional view showing a cutter bit made of conventional structural alloy steel carburized and hardened, and Fig. 2 shows a cutter bit made of precipitation hardening heat-resistant steel subjected to simultaneous nitriding and aging treatment according to the present invention. A partial sectional view of the same type as in FIG. 1, and FIGS. 3 and 4 show the processed material and structural alloy steel SN of the present invention at room temperature and after heating for 4000 CI hours, respectively.
A diagram showing the hardness distribution according to distance from the surface of CM-29 material after the same treatment. Figure 5 shows the tensile strength, hardness, and impact of the invention material as a result of changes in nitriding temperature (simultaneous aging treatment). Figure 6 is a correlation diagram showing the influence on the surface and internal hardness due to the difference in the treatment method of air nitriding treatment only, {B) solution treatment, nitriding aging treatment, 'C} solution treatment and aging treatment. Figure 7 is a correlation diagram showing the effects of nitriding treatment only.
It is a diagram showing the influence on the impact value due to the difference in treatment methods of 'B) solution treatment, nitriding/aging treatment, and 'C) port body treatment and aging treatment. 2... Structural alloy steel cutter bit body, 2A...
・Outer carburized hardened layer, 2B...Inner carburized hardened layer, 4
... Cutter bit body made of precipitation hardening type heat resistant steel, 4A.
...Outer nitrided hardened layer, 4B...Inner nitrided hardened layer. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Completed diagram

Claims (1)

[Claims] 1 A process of manufacturing a Katsutervit material by casting molten precipitation-hardened heat-resistant steel into a mold created by the lost wax method, a process of solution-treating the material, and a nitriding and aging treatment of the solution-treated material. 1. A method for producing a heat-resistant tooth-shaped cutter bit, comprising the steps of: