JPH0361345A - Hot-working tool made of ni-base alloy and aftertreatment for same - Google Patents

Abstract

PURPOSE:To increase deformation resistance and to improve durability by applying carburizing treatment to a tool made of Ni-base alloy having a specific composition containing W and further subjecting the tool to diffusion annealing treatment and to oxidation treatment. CONSTITUTION:A hot-working tool has a composition consisting of, by weight, <=0.1% (C+N), <=3% Si, 0.01-2.0% Mn, <=0.02% P, <=0.01% S, 20-60% W, and the balance essentially Ni. The above tool is subjected to carburizing treatment consisting of heating at 800-1250 deg.C for 1-20hr. Subsequently, the tool is subjected to diffusion annealing treatment at 800-1250 deg.C for 1-10hr and further to oxidation treatment consisting of heating up to 800-1400 deg.C for 0.1-10hr under a partial pressure of oxygen not higher than atmospheric pressure. If necessary, proper amounts of Mo, one or more elements among Fe, Co, Ti, Al, V, and Cr, and one or more elements among rare earths, Mg, Zr, and Ca are incorporated to the above Ni-base alloy. This hot-working tool has high melting point and superior toughness at high temp., ductility at high temp., and toughness at room temp.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a hot tool made of a Ni-based alloy that is resistant to deformation, melting damage, seizure, cracking, etc. at high temperatures and has excellent durability. For example, the present invention relates to hot tools such as perforation plugs and mandrels used in the production of seamless steel pipes, and post-treatment methods for further improving the durability of the tools.

(Prior art) For example, in the production of seamless steel pipes using Mannesmann plug mills or mandrel mills, high-temperature solid round steel pieces are processed into hollow pipes by a piercer equipped with pipe-making tools such as drilling plugs and guide shoes. be done.

Alternatively, in the production of seamless steel pipes using the Eugene-Séjournet method, a hot solid round piece of steel is processed into a hollow mother pipe using an extrusion press equipped with a mandrel and a die.

Since these hot tools are subjected to high temperatures and extremely high pressures during use, they require the following characteristics.

■High strength at high temperatures (prevention of deformation), ■Excellent ductility at high temperatures (prevention of cracking during processing), ■Excellent toughness at room temperature (prevention of cracking during handling and early processing), ■Good heat cracking resistance (Prevention of cracking due to repeated temperature rise and fall), ■Excellent surface lubricity (suppression of seizure and surface temperature rise)
, ■High melting point (prevention of melting damage due to rise in surface temperature), etc.

Hot tools are required to have such properties, so conventionally, so-called high-temperature materials have been used for their materials. These are high-temperature materials such as Fe-based alloys containing 3% by weight or less in total, or Inconel 718 (trade name), which is a Ni-based alloy.

These high-temperature materials have excellent properties up to temperatures of about 1000°C, so if the workpiece is a material with low deformation resistance, such as ordinary steel, hot tools made of these high-temperature materials are sufficient. .

However, in recent years, the environment in which seamless steel pipes are used has become increasingly harsh, and as a result, alloy steel pipes such as stainless steel, so-called high alloy pipes such as Ni-based alloys, Ti, Ti alloys, Zr, and Zr alloys, etc. The need for this is increasing. These alloy steels and high alloys have higher deformation resistance than ordinary steel, so
Hot work tools have become subject to higher stresses and friction.

For example, if the solid round piece of workpiece is stainless steel,
In a piercer, the surface of the piercing plug and guide shoe can reach temperatures of over 1200°C due to frictional heat, and up to 1300°C depending on pipe manufacturing conditions.
The temperature rises to above. In particular, if no measures are taken to improve the lubricity of the surface, the outermost layer will be heated to 1400
In addition, stress of 20 kgf/vua or more on average, and in some cases 30 kgf102 or more, is applied to the perforated plug and guide shoe. In some cases, such severe conditions continue for 30 seconds or more for one punch.

In the case of the Eugene-Sejournet method, the time required for extrusion is short, but the surfaces of the die and mandrel are subject to the same severe conditions as described above. In this Eugene-Séjournet method, the workpiece materials include super alloys, Ti, Ti alloys, Zr-, and Zr alloys, so the tool contains 40
In some cases, stress exceeding "kgf/srs" may be applied.

Thus, when machining alloyed steels or high alloys, the tools are subjected to high temperatures and high stresses and friction. For this reason, when machining alloy steel or high alloys with conventional hot tools made of high-temperature materials, the tools may suffer deformation, wear, seizure, melting damage, etc., and as shown in the examples below, the tool life may be extremely short. , - Such a problem occurs during the processing of a book, and the processing itself becomes impossible.

Therefore, in order to improve the durability of hot-working tools, it is recommended to coat the tool surface with various ceramics such as aluminum oxide or aluminum nitride, or to use Mo, Nb, or their alloys, which have excellent high-temperature strength, as tool materials. It is being considered. However, although the method of coating ceramics can improve the deformation resistance, heat resistance, and lubricity of the tool, it does not greatly improve the durability because CeraQ7 easily peels off. , N
b or a method using these alloys, Mo and Nb
In addition to being expensive, these elements sublimate and absorb oxygen, resulting in wear due to sublimation and embrittlement due to oxygen absorption, resulting in a short lifespan despite their high cost.

(Problems to be Solved by the Invention) The problems of the present invention are that even if workpiece materials such as alloy steel and high alloys have high deformation resistance and are subjected to severe processing conditions are hot-processed, deformation, melting loss, and seizure may occur. , a highly durable hot-working tool made of a Ni-based alloy that does not easily cause cracks, etc., and a post-treatment method that can further improve durability by forming a film with heat insulation or lubricity on the tool surface. Our goal is to provide the following.

Specifically, the present invention provides (a) a melting point of 1400°C or higher, (
+)) High temperature strength at 1200℃ is at least 20kgf
/am" or more, preferably the high temperature strength at 1300"C is 30 kgf/sin" or more, (C) the high temperature ductility at 1200 °C is at least 40% or more, preferably the high temperature ductility at 1300 °C is 40% or more, ( d) Toughness at room temperature is 2 kg
-m/c- or more, (e) an oxide film with a thickness of 10 to 150 μm that has lubricating and heat insulating properties, and (f) a lubricating film with a thickness of lO to 150 μm. An object of the present invention is to provide a post-treatment method that can form a hardened surface layer on the surface of a tool.

(Means for Solving the Problems) The present inventors have conducted extensive studies on materials whose melting point, high-temperature strength, and high-temperature ductility satisfy the above conditions.

High Cr ferritic steel, as a material with excellent high temperature strength)
ii-based alloy, Co-based alloy, carbide, or oxide.

Ultra-strong heat-resistant alloys such as cermets, which are sintered composite materials of metals and high-melting-point substances such as nitrides, are known. but,
High Cr ferritic steel containing 15% by weight or more of Cr produces Cr oxides with excellent oxidation resistance on the surface, but the oxide film is as thin as 8μ or less, so it has poor lubrication and heat insulation effects, and Ni-based alloys and Co-based alloys, which easily cause seizure because their melting points are below 1400°C, do not have high-temperature strength that satisfies the condition (b) above, and Co%
Alloys are expensive. Cermet has poor ductility and toughness at room and high temperatures, and easily cracks during processing.

For this reason, conventional heat-resistant alloys are not suitable for alloy steel and high-alloy tool materials.

However, the present inventor discovered that by devising the composition of the Ni-based alloy, high-temperature strength, high-temperature ductility, and room-temperature toughness can be improved, and if a hot work tool made of this devised Ni1 alloy is subjected to appropriate post-treatment, It has been found that lubricity, heat resistance, etc. are improved. This knowledge can be summarized as follows.

(]) When Ni is alloyed with W, the melting point becomes 1400°C or higher.

Among these, those containing 20 to 60% by weight of W are
It has high high temperature strength, as well as good high temperature ductility and room temperature toughness. In particular, those containing 35% by weight or more of W are α
- The former is dispersed and has the highest high temperature strength.

(2) If an appropriate amount of Mo is further added to the N1 to W alloy containing 20 to 1% of W, the high temperature strength is further improved.

(3) Fe, Go, Tt, ^poor, V, (:r are effective in forming an oxide film with lubricating properties. In addition, rare earth elements, Mg, Zr, and Ca improve hot ductility and oxide film formation. Effective in improving peeling resistance.

(4) If a hot tool made of this N1-W alloy is subjected to treatments such as oxidation, carburization, and diffusion annealing, the durability of the tool will be further improved.

The present invention was completed based on such knowledge, and its gist is in (i) and (ii) below.

(i) In weight%, C+N: 0.1% or less, Si: 3% or less, Mn: 0.01 to 2.0%, P: 0.02
% or less, S: 0.01% or less, W: 20 to 60%, and further contains at least one component selected from the following groups A, B, and 0 as necessary. A hot work tool made of a Ni-based alloy, the remainder of which is substantially composed of Ni.

[Group A] 1-10% Mo.

[Group B]

Fe below IO%, Co below 20%, Ti below 3%, ^poor below 3%, V below 3%, C below 10%
r.

[Group C]

0.05% or less of rare earth elements, 0.05% or less of Mg,
Zr of 0.05% or less, Ca of 0.05% or less.

(11) A post-treatment method for a hot-work tool made of a Ni1 alloy, which comprises subjecting the hot-work tool made of a Ni-based alloy described in (1) above to the following treatments.

■ Ash soaking treatment by heating at a temperature of 800 to 1250°C for 1 to 20 hours.

(2) Carburizing treatment that is heated to a temperature of 800 to 1250°C for 1 to 20 hours, and diffusion annealing treatment that is heated to a temperature of 800 to 1250°C for 1 to 10 hours.

(2) Oxidation treatment by heating at a temperature of 800 to 1400°C for 0.1 to 10 hours under an oxygen partial pressure below atmospheric pressure.

(2) Carburizing treatment by heating at a temperature of 800-1250°C for 1-20 hours and oxidation treatment by heating at a temperature of 800-1400°C for 0.1-10 hours under an oxygen partial pressure below atmospheric pressure.

■ Carburizing treatment heated to a temperature of 800 to 1250℃ for 1 to 20 hours, diffusion annealing treatment heated to a temperature of 800 to 1250℃ for 1 to 10 hours, and 800℃ heated to a temperature of 800 to 1250℃ for 1 to 10 hours under an oxygen partial pressure below atmospheric pressure.
Oxidation treatment by heating to a temperature of ~1400°C for 0.1~IO hours.

Examples of the above-mentioned hot tools include plugs, guide shoes,
Typical examples include pipe-making tools such as mandrels and dies, forging dies, and hot rolling rolls.

(effect) The present invention will be explained in detail below.

First, N of the base material in the ML-based alloy hot tool of the present invention
The reason for limiting the chemistry and II precepts of I-based alloys as described above will be explained together with the effects.

C and N: 0.1% or less in total Both C and N have the effect of increasing high temperature strength through solid solution strengthening. However, on the other hand, it greatly lowers the melting point,
The total content of C and N is 0.1% or less.

Si: 3% or less Si is added for deoxidation, but since it lowers the melting point, its content is set to 3% or less. If it exceeds 3%, the melting point of the alloy will be less than 1400°C. In particular, the Si content is 0.05
% or less, the effect of improving high-temperature ductility becomes greater.

Mn: 0.01-2.0% Mn is added for deoxidation. In addition, Mn is S, which will be described later.
It has the effect of fixing and improving high-temperature ductility.

This effect is small when the content is less than 0.01%, and 2.0
%, the melting point of the alloy will be less than 1400°C.

p: o, o2% or less P is an element that deteriorates high temperature ductility and lowers the melting point. If the content exceeds 0.02%, it becomes impossible to secure the target high temperature ductility and melting point.

S: 0.01% or less S is an element that more significantly deteriorates high-temperature ductility and lowers the melting point than P. If the content exceeds 0.01%, it becomes impossible to secure the target high temperature ductility and melting point. In order to ensure high-temperature ductility of 40% or more at 1400°C or higher, it is desirable that P be 0°005% or less.

W: 20-60% W is a particularly important element in the present invention. When W is added to Ni, the melting point and high temperature strength of the alloy improve as the content increases. This is an effect unique to W that is not found in other additive elements.

Even if the W content is less than 20%, it is possible to ensure a melting point of 1400° C. or higher, but the improvement in high temperature strength is not large, so the desired high temperature strength cannot be obtained.

On the other hand, even if the W content exceeds 60%, for example 65%, the alloy has hot ductility of 40% or more, so tools can be made by forging. However, if W is contained in excess of 60%, the solidus temperature (temperature at which a solid starts to form from a liquid)
The upper limit is set at 60%, as production becomes difficult using normal melting methods such as vacuum induction melting, AOD, and VOD. The desirable W content is 30% or more, more preferably 3
It is 5% or more.

When the W content is 30% or more, α-mae (almost pure W) is dispersed, and the high temperature strength is further improved. When it is 35% or more, the α-pre content increases further, and especially when carburizing treatment is performed, WC increases, and high temperature strength and lubricity are further improved.

The remainder is substantially Ni. Il+ has a good melting point, room temperature toughness, and high temperature ductility, and is relatively inexpensive.

Note that "substantially" means that it may contain unavoidable impurities in addition to Ni.

The hot tool of the present invention is made of a Ni-based alloy having the chemical composition described above. In addition to the above elements, at least one selected from the following groups A, B, and C.
The hot tool may be made of a Ni-based alloy containing more than one component.

Group A = 1 to 10% of A0 Mo has the effect of increasing high temperature strength. However, if the content is less than 1%, the effect will be small, and if the content exceeds 10%, the melting point will decrease significantly.

Group B: 10% or less Fe, 20% or less Co, 3% or less Ti, 3% or less Al, 3% or less V, 10% or less Cr.

When one or more of these elements are added, an oxide film is formed on the tool surface during cooling after hot working or during oxidation treatment described below, which has the effect of improving heat insulation and lubricity. However, since other elements other than Co lower the melting point, the content of Fe is 10% or less, Ti is 3% or less, Al is 3% or less, ■ is 3% or less, and Cr is 10% or less.

Since Go is expensive, it is economically disadvantageous to include it in excess of 20%.

Note that among the above elements, Fe, Co, and V form a low melting point oxide film, and AjLTi forms a high melting point oxide film. Both of these oxide films have the effect of improving both heat insulation and lubricity, but if anything, the former low melting point oxide film has a greater effect on improving lubricity, while the latter high melting point oxide film has a greater effect on improving lubricity. The oxide film has a greater effect on improving heat insulation.

Group C: 0.05% or less of rare earth elements, 0.05% or less of I'1g, 0.05% or less of Zr, 0.05% or less of Ca.

Adding one or more of these elements has the effect of improving high-temperature ductility. In addition, these elements enter the oxide film formed at high temperatures, densify the oxide film, and have the effect of suppressing peeling, cracking, wear, etc. during processing. However, if each content exceeds 0.05%, a low melting point compound is formed and the melting point and high temperature ductility are lowered.

In the present invention, the rare earth elements include Y, La, Ce,
Or a mixture thereof.

The hot tool of the present invention is made of a Ni-based alloy having the chemical composition described above. This Ni-based alloy has a high melting point, excellent high-temperature strength, high-temperature ductility, and room-temperature toughness, and has appropriate lubricity and heat insulation properties, so even if it is made into tools using normal manufacturing methods, it cannot be made with alloy steel or high-temperature steel. It can be fully used for processing alloys, and its service life is longer than that of conventional hot tools. and,
The tool life can be further improved.

Appropriate conditions for these post-treatments are as follows.

[Carburizing treatment = heating at 800 to 1250°C for 1 to 20 hours]
If the hot tool made of the Ni-based alloy is carburized to form a hardened layer with an appropriate thickness on the surface, the lubricity and wear resistance will be improved.

However, if the treatment temperature is less than 800°C or the treatment time is less than 1 hour, the carburized layer formed will be as thin as 10 μm or less, and the surface hardness will be as low as 900 or less on the Vickers hardness (Hv), resulting in poor lubricity and wear resistance. The improvement is small, while 1
At a treatment temperature exceeding 250°C or a treatment time exceeding 20 hours, the surface hardness is sufficiently high as 1100 or more in Hv.
Since the hardened layer is too thick (more than 150μ), cracking and peeling occur during processing. Therefore, the life of the tool is worse than that of a tool that is not carburized, that is, the life of the tool is shortened by carburizing.

In the carburizing process, Ni containing 35% or more of W generated before α-
It is effective to apply it to hot tools made of base alloys.

When this material is carburized, the α-front becomes hard and has high high-temperature strength WC due to carburization, so the lubricity, heat resistance, and wear resistance are significantly improved. Among these, the improvement in lubricity is significant.

[Diffusion annealing treatment: Heat phosphorus diffusion annealing treatment at 800 to 1250° C. for 1 to 10 hours. Performed as necessary after carbon treatment.

WC, which is hard and has high high-temperature strength, can be formed by carburizing alone, but if diffusion annealing is further performed after carburizing, WC increases and the carbon content of the matrix decreases.
WC due to wear! The high temperature strength, lubricity, and wear resistance are improved by preventing lI separation and increasing WC.

In diffusion annealing, if the treatment temperature is less than 800"C or the treatment time is less than 1 hour, no increase in WC can be expected, but rather the lubricity and wear resistance obtained by carburizing treatment will be reduced, so the tool life will be shortened. Although it is longer than that without post-treatment, it is shorter than that with carburizing treatment.On the other hand, even if diffusion annealing is performed at a treatment temperature exceeding 1250°C or a treatment time longer than 20 hours, the effect is saturated and it is economical. This will result in a disadvantage.

[Oxidation treatment: 800-1400 under oxygen partial pressure below atmospheric pressure
heating at a temperature of 0.1 to 10 hours] The oxidation treatment may be performed alone, or after carburization treatment, or after carburization treatment and diffusion annealing treatment.

If oxidation treatment is performed after carburizing or after carburizing and diffusion annealing, the lubricity and heat insulation properties will be further improved, so the tool life will be longer than that of carburizing alone or carburizing and diffusion annealing. become longer.

Even by thermal theory and oxidation treatment alone, an oxide film having lubricating and heat insulating properties can be formed on a hot tool made of a Ni-based alloy, and the tool life can be improved.

In the oxidation treatment, if the treatment temperature is less than 800° C. or the treatment time is less than 0.1 hour, an oxide film with a sufficient thickness (10 μm or more) cannot be obtained, so that the improvement in lubricity and heat insulation properties is small.

On the other hand, if the processing temperature exceeds 1400°C or the processing time exceeds 10 hours, the oxide layer that is formed will become too thick, for example, over 150 μm, which will result in cracking and peeling during processing, which will shorten the tool life. No improvement can be expected, and in some cases, the condition may become worse than that without treatment.

Furthermore, although only this oxidation treatment was performed within the condition range specified by the present invention, compared to carburizing treatment or carburization treatment and diffusion annealing treatment performed within the condition range specified by the present invention, the insulation and lubrication properties were Although it has excellent properties, it has poor high-temperature strength and wear resistance, so the tool life will not be long, but it will naturally be longer than the untreated one.

It is best to perform this oxidation treatment under an oxygen partial pressure below atmospheric pressure.
That is, Fe, Co, Ti, Affi, V, Cr
Among the oxide films such as Ti and Aj!, which have a high melting point and excellent heat insulation properties, as mentioned above, Ti and Aj! The oxide film is formed below (on the base metal side) the oxide film of Fe, Co, V, and even Si, which have a low melting point and excellent lubricity. However, under oxygen partial pressure exceeding atmospheric pressure, Fe, Go, V
, the Si oxide film is preferentially formed, and the Ti and Al oxide films below it do not grow to a sufficient thickness,
It is not possible to form an oxide film that has both lubricity and heat insulation properties. However, if the oxygen partial pressure is below atmospheric pressure, the oxidation of Fe, Co, Si, etc. is suppressed.
Ti, AI! The oxide film can be grown to a sufficient thickness to form an oxide film that has both lubricity and heat insulation properties.

Note that the tool whose service life can be significantly extended by applying this oxidation treatment is a steel whose steel composition contains an element selected from Group B, which is added for the purpose of forming an oxide film, from Groups A to C. , in the case of steels containing elements selected from other groups, the effect is small.

Hereinafter, the effects of the present invention will be illustrated by examples.

(Example 1) Ingots made of alloys having the chemical properties shown in Table 1 were melted, and plugs of two sizes were made from these ingots in the following manner.

Alloys 1 and 2 ingots (16
0m-diameter x 2000s+m length), and then
Cutting into a 50-diameter x 400m-long plug,
Invoking alloys 3 to 27 in a 17 kg vacuum induction melting furnace)
(90 m + i diameter x 300 - length) and melted this into 1
After hot forging at 200"c to make a round bar with a diameter of 551111, it was cut into a plug with a diameter of 50 mm and a length of 701I + w.

Using the plug prepared in this way, 1180-1
5tlS 304 heated to 230°C (deformation resistance:
A seamless steel pipe was drilled using a solid round steel piece of 8 kg/ms+'' at 1200°C.Drilling was continued until the plug could no longer be used.

In addition, for a 150mm diameter plug, 187*a+diameter*2
M 5IIS304 round steel piece, 50m-diameter plug, 70m diameter x 2 SO3304 round steel piece, both with a drilling ratio of 3 (perforation ratio is ``length after drilling J/' drilling length) ”) was perforated.

Table 2 shows the number of perforations until the plug becomes unusable (the number of pipes that can be made) and the results of investigating the characteristics of the plug material.

(Hereinafter, blank space) As is clear from Table 2, plugs made of alloys 15 to 24 (comparative example) and plugs made of alloys 25 to 27 (
The conventional example) is inferior in melting point, high temperature strength, and room temperature ductility, and as a result, the drilling life is short or drilling is impossible.

On the other hand, plugs made of alloys 1 to 14 (examples of the present invention) all have high melting points, high-temperature strength, and room-temperature ductility, and can be drilled more often than comparative and conventional examples, resulting in improved tool life. are doing.

(Example 2) The same alloys 1 to 3 and alloys 6 to 3 used in Example 1
A plug consisting of 14 was carburized under the conditions shown in Table 3.
After being subjected to post-treatment of diffusion annealing treatment and oxidation treatment, either alone or in combination, the SO3304 round steel pieces were used for drilling seamless steel pipes. Drilling was continued until the plug became unusable.

Note that the drilling conditions, plug size, and round steel billet size are the same as in Example I.

Table 3 shows the results and conditions for each treatment.

The number of perforations was expressed as an increase or decrease from the number of perforations of a plug made of the same alloy used in Example 1, which was not subjected to post-treatment.

That is, in the table, for example, "-5" means that the number of holes is 5 fewer than that of the same alloy plug without post-treatment, and "5" means that the number of holes is 5 more.

(Hereafter, blank space) As is clear from Table 3, the number of holes perforation increases when carburizing treatment and oxidation treatment are performed individually under appropriate conditions, or when carburization treatment, diffusion annealing treatment, and oxidation treatment are performed in combination. (Example of the present invention), in contrast, an example where only diffusion treatment was performed under inappropriate conditions (N113.4 of the comparative example) and an example where only oxidation treatment was performed under inappropriate conditions (the aim of the comparative example) 11, 12, 42, and 43), the number of perforations is significantly reduced or not increased at all compared to those not subjected to these treatments.

In addition, as in Comparative Example 7 to N [L9, even if carburized under appropriate conditions, diffusion annealing is inappropriate and the number of holes perforated is lower than when only diffusion treatment is performed under the same conditions. , the effect of diffusion annealing is saturated.

That is, the diffusion treatment temperature is low, and the treatment time is short, N.
No. 119 has fewer holes perforated than No. 5 which was subjected to diffusion treatment under the same conditions, and No. 8, which has a long treatment time, has no improvement compared to No. Those subjected to oxidation treatment under the following conditions (comparison side stone 1)
5) The number of perforations is significantly lower than that without treatment.
However, if the subsequent oxidation treatment is carried out under appropriate conditions (
Although the decrease in the number of perforations in Comparative Example Na14) is suppressed by the effect of the oxidation treatment, it is smaller than that in the case without treatment.

In addition, Comparative Examples Na17 and 18 were carburized under appropriate conditions and then diffusion annealed under inappropriate conditions. The number of holes perforated in both cases is greater than that without treatment. However, compared to Example 16 of the present invention in which all of the carburizing treatment, diffusion annealing treatment, and oxidation treatment were performed under appropriate conditions, the increase in the number of perforations is small.

(Effects of the Invention) As shown in the examples, the Ni-based alloy hot work tool of the present invention has a high melting point, high a toughness, high temperature ductility, and room temperature toughness, and is superior to stainless steel with high deformation resistance. Even when machining alloy steels such as Ni1 alloy, Ti and its alloys, Zr and its alloys, etc., there is little deformation, seizure, melting loss, etc., and the tool life is long.

Note that the Ni-based alloy hot work tool of the present invention can of course be used for machining ordinary steel and low alloy steel.

Claims (1)

[Claims] (1) In weight%, C+N: 0.1% or less, Si: 3% or less, Mn: 0.01 to 2.0%, P: 0.02% or less,
A hot work tool made of a Ni-based alloy, containing S: 0.01% or less, W: 20 to 60%, and the remainder substantially consisting of Ni. (2) In weight%, C+N: 0.1% or less, Si: 3% or less, Mn: 0.01 to 2.0%, P: 0.02% or less,
Contains S: 0.01% or less, W: 20 to 60%, and further contains at least one component selected from the following groups A, B, and C, with the remainder being substantially Ni. A hot work tool made of a Ni-based alloy. [Group A] 1-10% Mo. [Group B] 10% or less Fe, 20% or less Co, 3% or less Ti
, 3% or less Al, 3% or less V, 10% or less Cr. [Group C] 0.05% or less of rare earth elements, 0.05% or less of Mg,
Zr of 0.05% or less, Ca of 0.05% or less. (3) The Ni-based alloy hot tool according to claim (1) or (2) is carburized by heating it to a temperature of 800 to 1250°C for 1 to 20 hours. Post-processing method for intermediate tools. (4) The Ni-based alloy hot work tool according to claim (1) or (2) is carburized by heating to a temperature of 800 to 1250°C for 1 to 20 hours, and then heated to a temperature of 800 to 1250°C for 1 to 20 hours. ~
N characterized by being heated for 10 hours and subjected to diffusion annealing treatment.
Post-treatment method for hot tools made of i-based alloys. (5) The Ni-based alloy hot work tool according to claim (1) or (2) is oxidized by heating it to a temperature of 800 to 1400°C for 0.1 to 10 hours under an oxygen partial pressure below atmospheric pressure. A method for post-processing a hot tool made of a Ni-based alloy, characterized by: (6) 1 to 1 at a temperature of 800 to 1250°C according to claim (3)
After carburizing treatment by heating for 20 hours or 800 of claim (4)
After diffusion annealing treatment of heating to a temperature of ~1250°C for 1 to 10 hours, an oxidation treatment of heating to a temperature of 800 to 1400°C for 0.1 to 10 hours under an oxygen partial pressure below atmospheric pressure. Post-treatment method for hot alloy tools.