JP7498443B2 - Manufacturing method of hot forged material - Google Patents
Manufacturing method of hot forged material Download PDFInfo
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- JP7498443B2 JP7498443B2 JP2023546773A JP2023546773A JP7498443B2 JP 7498443 B2 JP7498443 B2 JP 7498443B2 JP 2023546773 A JP2023546773 A JP 2023546773A JP 2023546773 A JP2023546773 A JP 2023546773A JP 7498443 B2 JP7498443 B2 JP 7498443B2
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- 239000000463 material Substances 0.000 title claims description 169
- 238000004519 manufacturing process Methods 0.000 title claims description 16
- 238000005242 forging Methods 0.000 claims description 207
- 239000011810 insulating material Substances 0.000 claims description 73
- 239000011521 glass Substances 0.000 claims description 63
- 238000000034 method Methods 0.000 claims description 59
- 238000010438 heat treatment Methods 0.000 claims description 49
- 239000000314 lubricant Substances 0.000 claims description 42
- 238000000576 coating method Methods 0.000 claims description 18
- 239000002245 particle Substances 0.000 claims description 14
- 239000012784 inorganic fiber Substances 0.000 claims description 8
- 239000003779 heat-resistant material Substances 0.000 claims description 2
- 229910045601 alloy Inorganic materials 0.000 description 34
- 239000000956 alloy Substances 0.000 description 34
- 230000007547 defect Effects 0.000 description 12
- 239000011248 coating agent Substances 0.000 description 9
- 238000009721 upset forging Methods 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 8
- 210000002268 wool Anatomy 0.000 description 8
- 230000007423 decrease Effects 0.000 description 6
- 229910001247 waspaloy Inorganic materials 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 238000005336 cracking Methods 0.000 description 5
- 239000012774 insulation material Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 230000003746 surface roughness Effects 0.000 description 5
- 239000002759 woven fabric Substances 0.000 description 5
- 230000001070 adhesive effect Effects 0.000 description 4
- 239000000835 fiber Substances 0.000 description 4
- 239000000919 ceramic Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- 238000005507 spraying Methods 0.000 description 3
- 229910001069 Ti alloy Inorganic materials 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000017525 heat dissipation Effects 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 229910000601 superalloy Inorganic materials 0.000 description 2
- 238000005452 bending Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000006060 molten glass Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000004227 thermal cracking Methods 0.000 description 1
- 238000011179 visual inspection Methods 0.000 description 1
- 230000037303 wrinkles Effects 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J1/00—Preparing metal stock or similar ancillary operations prior, during or post forging, e.g. heating or cooling
- B21J1/003—Selecting material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J1/00—Preparing metal stock or similar ancillary operations prior, during or post forging, e.g. heating or cooling
- B21J1/02—Preliminary treatment of metal stock without particular shaping, e.g. salvaging segregated zones, forging or pressing in the rough
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J1/00—Preparing metal stock or similar ancillary operations prior, during or post forging, e.g. heating or cooling
- B21J1/06—Heating or cooling methods or arrangements specially adapted for performing forging or pressing operations
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J3/00—Lubricating during forging or pressing
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Forging (AREA)
Description
本発明は、熱間鍛造材の製造方法にかかり、特には、難加工性合金製の熱間鍛造材の製造方法に関するものである。 The present invention relates to a method for manufacturing hot forged material, and in particular to a method for manufacturing hot forged material made of a difficult-to-process alloy.
熱間鍛造温度に加熱した熱間鍛造用素材を熱間鍛造する場合、熱間鍛造用素材の温度低下による熱間加工性の低下の問題がある。そのため、従来から種々の温度低下防止の提案がなされてきた。例えば、特表２０１４－５０８８５７号公報（特許文献１）には、熱間鍛造用素材にガラスコーティングすることより、熱クラッキングを防止している。そのガラスコーティングの方法として、熱間鍛造用素材にガラス織布とガラス粒子とを順番に配置するとしている。また、この特許文献１中には、熱間加工前に熱間鍛造用素材を金属合金製缶内に封入することが従来技術として示されている。When hot forging a hot forging material heated to the hot forging temperature, there is a problem of a decrease in hot workability due to a decrease in the temperature of the hot forging material. For this reason, various proposals have been made in the past to prevent temperature decreases. For example, in JP-T 2014-508857 (Patent Document 1), thermal cracking is prevented by glass coating the hot forging material. The glass coating method involves arranging glass woven fabric and glass particles in order on the hot forging material. Patent Document 1 also shows that a conventional technique involves sealing the hot forging material in a metal alloy can before hot working.
前述の特許文献１では、その実施例で示されるように、室温でガラス織布を熱間鍛造用素材に巻き付け、そのガラス織布表面に無機スラリーを塗布し、その状態で熱間鍛造温度に加熱し、ガラスコーティング層を形成している。この方法は、確かに加熱炉から熱間鍛造用素材を取り出して、熱間鍛造開始までの温度低下抑制には効果的である。しかしながら、ガラス織布そのものは断熱効果を有するものであるため、鍛造温度までの加熱時間が長くなり、また、特許文献１の図３で示されるような、全体をガラス織布で包む方法では、熱間鍛造用素材自体の温度が分かり難いという欠点がある。
ところで、熱間鍛造温度に加熱した熱間鍛造用素材を熱間鍛造開始するまでの温度低下や熱間鍛造中の温度低下が熱間加工性を低下させる代表的な合金に、難加工性合金として知られるγ’相（ガンマプライム相）の量を体積％で２０％以上含むようなＮｉ基合金やＴｉ合金がある。これらの難加工性合金は、高温強度に優れているため、航空機部品や発電設備用部品に用いられる。これらの用途は、燃焼効率向上や発電効率向上を目的として製品の大型化の要求があるものや、γ’量を体積％で２０％以上含むようなＮｉ基合金（以下、γ’高含有Ｎｉ基合金）では、より高温での使用が検討されている。熱間鍛造温度が割れや疵の不良の発生に影響を及ぼし、特に、γ’高含有Ｎｉ基合金では、熱間鍛造可能な温度域が限定されるものもある。熱間加工性と割れなどの不良防止の両立が重要となり、熱間鍛造時の割れを防止しつつ、効率よく熱間鍛造する方法が求められている。
本発明の目的は、熱間鍛造用素材として難加工性合金を用いても、割れなどの不良を防止しつつ、効率よく熱間鍛造が可能な熱間鍛造材の製造方法を提供することである。
In the above-mentioned Patent Document 1, as shown in the examples, a glass woven fabric is wrapped around a hot forging material at room temperature, an inorganic slurry is applied to the surface of the glass woven fabric, and the material is heated to a hot forging temperature in this state to form a glass coating layer. This method is certainly effective in suppressing the temperature drop from when the hot forging material is removed from the heating furnace until the hot forging begins. However, since the glass woven fabric itself has a heat insulating effect, the heating time to the forging temperature is long, and the method of wrapping the entire material with glass woven fabric as shown in Figure 3 of Patent Document 1 has the disadvantage that it is difficult to know the temperature of the hot forging material itself.
Incidentally, typical alloys in which the temperature drop before the start of hot forging of a hot forging material heated to the hot forging temperature or the temperature drop during hot forging reduces the hot workability include Ni-based alloys and Ti alloys containing 20% or more by volume of γ' phase (gamma prime phase), which is known as a difficult-to-work alloy. These difficult-to-work alloys are used for aircraft parts and power generation equipment parts because of their excellent high-temperature strength. These applications include those in which there is a demand for larger products in order to improve combustion efficiency and power generation efficiency, and Ni-based alloys containing 20% or more by volume of γ' (hereinafter referred to as γ'-rich Ni-based alloys) are being considered for use at higher temperatures. The hot forging temperature affects the occurrence of defects such as cracks and scratches, and in particular, some γ'-rich Ni-based alloys have a limited temperature range in which they can be hot forged. It is important to achieve both hot workability and prevention of defects such as cracks, and a method for efficiently hot forging while preventing cracks during hot forging is required.
An object of the present invention is to provide a method for producing a hot forged material that enables efficient hot forging while preventing defects such as cracks, even when a difficult-to-work alloy is used as a raw material for hot forging.
本発明は上述した課題に鑑みてなされたものである。
すなわち本発明は、熱間鍛造する加熱前素材を加熱炉中で熱間鍛造温度に加熱する加熱工程と、
前記加熱炉から取り出した鍛造用素材の少なくともその表面の一部に、耐熱断熱材を接着させて熱間鍛造用素材とする耐熱断熱材接着工程と、
金型、金敷、工具の何れかを用いて、前記熱間鍛造用素材の一部または全体を圧縮して所定の形状に成形する熱間鍛造工程と、
を含み、
更に、前記加熱前素材表面の、少なくとも前記耐熱断熱材を接着する部分にはガラス潤滑剤を被覆するガラス潤滑剤被覆工程と、
を含み、
前記ガラス潤滑剤が、前記耐熱断熱材接着工程において１０２～１０７Ｐａ・ｓの粘度を有するものである熱間鍛造材の製造方法である。
また本発明は、前記熱間鍛造工程が自由鍛造であり、前記自由鍛造で前記金型、金敷、工具の何れかに接触しない鍛造用素材の自由変形部分の少なくともその表面の一部に、前記耐熱断熱材を接着させる熱間鍛造材の製造方法である。
また、本発明において、前記耐熱断熱材の前記鍛造用素材と接着する面には、ガラス粒子が付着していても良い。
好ましくは、前記耐熱断熱材は無機繊維である熱間鍛造材の製造方法である。
The present invention has been made in view of the above-mentioned problems.
That is, the present invention includes a heating step of heating a pre-heated material to be hot forged to a hot forging temperature in a heating furnace;
A heat-resistant insulating material bonding process for bonding a heat-resistant insulating material to at least a part of the surface of the forging material removed from the heating furnace to prepare a hot forging material;
A hot forging process in which a part or the whole of the hot forging material is compressed and formed into a predetermined shape using a die, an anvil, or a tool;
Including,
Furthermore, a glass lubricant coating process is performed to coat at least a portion of the surface of the pre-heated material to which the heat-resistant insulating material is to be bonded with a glass lubricant.
Including,
In the method for producing a hot forged material, the glass lubricant has a viscosity of 10 2 to 10 7 Pa·s in the heat-resistant and heat-insulating material bonding step.
The present invention also relates to a method for producing hot forged material, in which the hot forging process is free forging, and the heat-resistant insulating material is adhered to at least a portion of the surface of a freely deforming portion of the forging material that does not come into contact with any of the mold, anvil, or tool during the free forging.
In the present invention, glass particles may be attached to the surface of the heat-resistant insulating material that is bonded to the forging material.
Preferably, in the method for producing a hot forged material, the heat resistant and insulating material is an inorganic fiber.
本発明によれば、熱間鍛造用素材として難加工性合金を用いても、割れなどの不良を防止しつつ、効率よく熱間鍛造を行うことが可能である。According to the present invention, even when a difficult-to-work alloy is used as a material for hot forging, it is possible to perform hot forging efficiently while preventing defects such as cracks.
以下に、本発明を工程ごとに説明する。なお、以下で記す「加熱前素材」とは、加熱炉に装入する前の素材を言い、「鍛造用素材」とは、加熱炉で熱間鍛造温度に加熱された素材を言い、「熱間鍛造用素材」とは、所定の部分に耐熱断熱材を接着させて、熱間鍛造が行える状態となったものを言い、「熱間鍛造材」とは、熱間鍛造装置によって所定の形状に成形された成形材を言う。
＜加熱工程＞
先ず、本発明では、熱間鍛造する加熱前素材を加熱炉中で熱間鍛造温度に加熱する。加熱前素材は、インゴット、ビレット、荒地、粉末成形体等、特に限定しないが、本発明の効果が最も発揮可能なものは、自由鍛造により所望の形状に成形を行うインゴットやビレットなどである。この加熱前素材を加熱炉中で熱間鍛造温度に加熱する。加熱の温度は加熱前素材の材質により異なり、例えば、Ｎｉ基合金では９５０～１１８０℃であれば良く、γ’高含有Ｎｉ基合金であれば１０１０～１１８０℃であれば良い。また、Ｔｉ合金であれば９００～１１８０℃であれば良い。なお、本発明においては、加熱工程の後に“耐熱断熱材接着工程”を適用する。耐熱断熱材接着工程では、加熱炉から取り出した鍛造用素材に対して耐熱断熱材を接着させる。この耐熱断熱材を接着させるまでの間、鍛造用素材の温度低下がゼロであれば好ましいが、実際には少なからず温度低下する。そのため、熱間鍛造を開始するときの鍛造温度（鍛造開始温度）よりも５～１００℃程度高めの温度を熱間鍛造温度に設定しても良い。このことにより、耐熱断熱材を接着しなければ、鍛造用素材の温度が、鍛造開始温度に対して１００℃を超えて低下してしまうような場合でも、その温度低下を抑えることができて、熱間鍛造中の温度を高く保持できる。
また、加熱前素材の材質がＮｉ基超耐熱合金である場合、殆どの合金でＣｒを１０～３５質量％の範囲で含有している。加熱工程中に加熱炉内の酸素とＣｒの反応を抑制する目的で、加熱炉内の酸素濃度を１０％以下に制御するのが好ましい。好ましくは８％以下である。
The present invention will be described below step by step. In the following, the term "unheated material" refers to a material before being charged into a heating furnace, the term "forging material" refers to a material heated to a hot forging temperature in a heating furnace, the term "hot forging material" refers to a material in which a heat-resistant insulating material is bonded to a predetermined portion and which is ready for hot forging, and the term "hot forging material" refers to a material formed into a predetermined shape by a hot forging device.
<Heating process>
First, in the present invention, the pre-heated material to be hot forged is heated to a hot forging temperature in a heating furnace. The pre-heated material may be an ingot, a billet, a rough surface, a powder compact, or the like, and is not particularly limited. However, the effects of the present invention can be most effectively achieved with ingots and billets that are formed into a desired shape by free forging. The pre-heated material is heated to a hot forging temperature in a heating furnace. The heating temperature varies depending on the material of the pre-heated material. For example, the heating temperature may be 950 to 1180°C for Ni-based alloys, and 1010 to 1180°C for γ'-rich Ni-based alloys. Also, the heating temperature may be 900 to 1180°C for Ti alloys. In the present invention, a "heat-resistant insulating material bonding process" is applied after the heating process. In the heat-resistant insulating material bonding process, a heat-resistant insulating material is bonded to the forging material removed from the heating furnace. It is preferable that the temperature of the forging material does not decrease to zero until the heat-resistant insulating material is bonded, but in reality, the temperature decreases to some extent. Therefore, the hot forging temperature may be set to a temperature about 5 to 100° C. higher than the forging temperature at the start of hot forging (forging start temperature).By doing so, even if the temperature of the forging material would drop by more than 100° C. below the forging start temperature if the heat-resistant insulating material is not attached, the temperature drop can be suppressed and the temperature during hot forging can be kept high.
In addition, when the material before heating is a Ni-based heat-resistant superalloy, most of the alloys contain 10 to 35 mass% of Cr. In order to suppress the reaction between oxygen and Cr in the heating furnace during the heating process, it is preferable to control the oxygen concentration in the heating furnace to 10% or less, and preferably 8% or less.
なお、この加熱前素材の表面粗さは並仕上げよりも粗い方が良く、次工程で耐熱断熱材をその表面に接着したときに、耐熱断熱材と鍛造用素材との間に僅かな空間が形成され、その空間内の空気が断熱層として機能することが期待できる。そして、後述する、ガラス潤滑剤被覆工程において、加熱前素材表面の凹凸にガラス潤滑剤が残留しやすくなる。もちろん、鋳造ままや塑性加工ままの表面肌でも良いが、難加工性合金の場合、添加元素の影響などにより表面にクラック等が発生する場合があるので、それらの熱間鍛造時の割れの発生原因となる表面欠陥は機械加工により除去しておくと良い。クラックなどの発生が見られない場合であっても、次工程で耐熱断熱材をその表面に接着する部分（つまり、ガラス潤滑剤を被覆する部分）については、加熱前素材表面を機械加工により並仕上げ以上の粗さに整えておくのが好ましい。In addition, the surface roughness of the pre-heated material is better than that of the normal finish, and when the heat-resistant insulating material is bonded to the surface in the next process, a small space is formed between the heat-resistant insulating material and the forging material, and the air in the space is expected to function as an insulating layer. In the glass lubricant coating process described later, the glass lubricant is likely to remain on the unevenness of the surface of the pre-heated material. Of course, the surface skin as cast or plastically processed is also acceptable, but in the case of difficult-to-process alloys, cracks may occur on the surface due to the influence of added elements, so it is better to remove surface defects that cause cracks during hot forging by machining. Even if no cracks are observed, it is preferable to machine the surface of the pre-heated material to a roughness of at least the normal finish for the part where the heat-resistant insulating material will be bonded to the surface in the next process (i.e., the part coated with the glass lubricant).
＜耐熱断熱材接着工程＞
加熱前素材を熱間鍛造温度に加熱して、加熱炉から取り出した鍛造用素材の少なくとも表面の一部の所定の部分に耐熱断熱材を接着させて熱間鍛造用素材とする。接着させる部分は表面の一部であっても、表面全体であっても差し支えない。この鍛造用素材表面のどこの部分に耐熱断熱材を接着するかは、下記の２つの何れかを考慮とすると良い。
１つ目の方法は、割れが予想される部分の温度低下を優先的に防止する方法である。耐熱断熱材を鍛造用素材に接着させる作業の時間が長くなると、鍛造用素材の温度が低くなってしまい、熱間鍛造性を劣化させる場合がある。そのため、熱間鍛造性を損なわない時間で、必要最小限の範囲に耐熱断熱材をその表面に接着させることが好ましい。例えば、熱間鍛造用素材を熱間鍛造装置に載置したとき、例えば、下型（下金敷または下側工具）への抜熱が心配されるときは、下型（下金敷または下側工具）と接する面に耐熱断熱材を接着させても良いし、多角形の柱状の形状であれば、エッジ部分を含む範囲に接着させても良い。円柱状であれば、その側面に接着しても良い。つまり、熱間鍛造によって、割れなどの不良が発生しやすい場所を含んで耐熱断熱材を接着させると良い。この方法は、特に、難加工性合金として知られるγ’高含有Ｎｉ基合金に対して有効である。
<Heat-resistant insulation material bonding process>
The pre-heated material is heated to a hot forging temperature, and the material for forging is removed from the heating furnace. A heat-resistant insulating material is attached to at least a predetermined portion of the surface of the material for forging to prepare a material for hot forging. The portion to be attached may be a portion of the surface or the entire surface. The portion to be attached to the surface of the material for forging may be determined by considering either of the following two points.
The first method is a method of preferentially preventing a temperature drop in the portion where cracking is expected. If the time required for adhering the heat-resistant insulating material to the forging material is long, the temperature of the forging material may be lowered, which may deteriorate the hot forgeability. Therefore, it is preferable to adhere the heat-resistant insulating material to the surface of the material in the minimum necessary range for a time that does not impair the hot forgeability. For example, when the hot forging material is placed on the hot forging device, for example, if there is a concern about heat dissipation to the lower die (lower anvil or lower tool), the heat-resistant insulating material may be adhered to the surface that contacts the lower die (lower anvil or lower tool), or if the shape is a polygonal columnar shape, it may be adhered to the range including the edge portion. If it is cylindrical, it may be adhered to the side surface. In other words, it is good to adhere the heat-resistant insulating material to the portion where defects such as cracks are likely to occur due to hot forging. This method is particularly effective for γ'-rich Ni-based alloys, which are known as difficult-to-work alloys.
２つ目の方法は、鍛造用素材の自由変形部分の少なくともその表面の一部に、前記耐熱断熱材を接着させる方法である。この方法は、例えば、熱間鍛造が自由鍛造である場合、上型（上金敷または上側工具）や下型（下金敷または下側工具）と接触していない部分は、大気中で放冷された状態になるため、その温度低下を低減させることを主としたものである。この方法は、例えば、７１８合金やワスパロイ等の熱間鍛造可能な温度域が広い合金において、加熱温度の持続性を持たせることができるため、疵（割れ）低減に寄与できる。
上記の方法の選択は、その材質や形状を考慮して選択すると良い。
この耐熱断熱材の接着により、熱間鍛造用素材の温度低下に伴う微細なγ’の析出を軽減する他、熱間鍛造用素材表層部の再結晶を促進させることが可能となることから、例えば、難加工性合金として知られるγ’高含有Ｎｉ基合金であっても、割れなどの不良の発生を軽減することができる。
The second method is to bond the heat-resistant insulating material to at least a part of the surface of the free deformation part of the forging material. This method is mainly intended to reduce the temperature drop of the part not in contact with the upper die (upper anvil or upper tool) or the lower die (lower anvil or lower tool) when the hot forging is free forging, since the part is left to cool in the air. This method can contribute to reducing defects (cracks) by making the heating temperature sustainable in alloys with a wide temperature range that can be hot forged, such as 718 alloy and Waspaloy.
The above method should be selected taking into consideration the material and shape of the material.
The adhesion of this heat-resistant insulating material not only reduces the precipitation of fine γ' that occurs when the temperature of the hot forging material is reduced, but also makes it possible to promote recrystallization of the surface layer of the hot forging material. Therefore, even in a Ni-based alloy with a high γ' content, which is known to be a difficult-to-work alloy, the occurrence of defects such as cracks can be reduced.
なお、前記耐熱断熱材接着工程において、耐熱断熱材の接着を容易且つ短時間で行うには、耐熱断熱材と、それを接着する鍛造用素材の接着面との間にガラス潤滑剤を存在させておくことが好ましい。このときのガラス潤滑剤は、主として「接着剤」として機能させるものである。そのための方法は２つあり、それぞれについて説明する。In addition, in order to bond the heat-resistant insulating material easily and quickly in the heat-resistant insulating material bonding process, it is preferable to have a glass lubricant between the heat-resistant insulating material and the bonding surface of the forging material to which it is bonded. The glass lubricant in this case functions mainly as an "adhesive." There are two methods for doing this, each of which will be explained below.
＜ガラス潤滑剤被覆工程＞
一つ目の方法は「ガラス潤滑剤被覆工程」を行うことである。これは、本発明が含む工程である。ガラス潤滑剤被覆工程は、前記加熱前素材表面の、少なくとも前記耐熱断熱材を接着する部分にガラス潤滑剤を予め被覆する工程を更に含むものである。ガラス潤滑剤は、前記加熱後の保温剤として作用することが可能であるため、特に、難加工性合金の熱間鍛造を行う場合に、有効である。そして、このときのガラス潤滑剤が、上記の鍛造用素材の接着面と耐熱断熱材との間で「接着材」として機能するためには、それが、温度が低いとき（つまり、ガラス潤滑剤被覆工程のとき）ではなくて、耐熱断熱材接着工程における環境温度に熱せられたときに、所定の粘度を発現する必要がある。そして、本発明の場合、上記の環境温度でのガラス潤滑剤の粘度が、１０２～１０７Ｐａ・ｓ（＝１０３～１０８Ｐ（ポアズ））であることが効果的である。好ましくは１０６Ｐａ・ｓ以下、より好ましくは１０５Ｐａ・ｓ以下である。また、好ましくは５×１０２Ｐａ・ｓ以上、より好ましくは１０３Ｐａ・ｓ以上である。粘度が高すぎると、ガラス潤滑剤の硬さが増して、粘着性の効果が発揮され難い。粘度が低すぎると、ガラス潤滑剤の流動性が増して、粘着性が低下し、また、鍛造用素材の表面にとどまり難くもなる。
<Glass lubricant coating process>
The first method is to carry out a "glass lubricant coating process". This is a process included in the present invention. The glass lubricant coating process further includes a process of coating at least the portion of the pre-heated material surface to which the heat-resistant insulating material is bonded with a glass lubricant in advance. The glass lubricant can act as a heat retaining agent after the heating, so it is particularly effective when hot forging a difficult-to-process alloy. In order for the glass lubricant to function as an "adhesive" between the bonding surface of the forging material and the heat-resistant insulating material, it is necessary for it to develop a predetermined viscosity when heated to the environmental temperature in the heat-resistant insulating material bonding process, not when the temperature is low (i.e., during the glass lubricant coating process). In the case of the present invention, it is effective that the viscosity of the glass lubricant at the above environmental temperature is 10 2 to 10 7 Pa·s (= 10 3 to 10 8 P (poise)). It is preferably 10 6 Pa·s or less, more preferably 10 5 Pa·s or less. Also, the viscosity is preferably 5×10 2 Pa·s or more, more preferably 10 3 Pa·s or more. If the viscosity is too high, the hardness of the glass lubricant increases, and the adhesive effect is difficult to be exhibited. If the viscosity is too low, the fluidity of the glass lubricant increases, the adhesiveness decreases, and it is difficult for the glass lubricant to remain on the surface of the forging material.
上記の環境温度は、耐熱断熱材接着工程で加熱炉から取り出したときの鍛造用素材の表面温度を想定して、加熱工程における「熱間鍛造温度」とすることができる。よって、ガラス潤滑剤の粘度は、上記の熱間鍛造温度のときの粘度とすることができる。そして、この粘度の測定は、次の２種類の要領から選択して実施することができる。一つは、薄い平板を溶融ガラスに浸漬させ振動を与えたときの振動振幅から粘度を算出し、粘度の低い高温域から温度を下げながら測定する方法である。もう一つは、固形化させた円柱状の試料に平行板で加圧したときの試料の高さと変形速度から粘度を算出し、粘度の高い低温域から温度を上げながら測定する方法である。
本発明に係るガラス潤滑剤は、耐熱断熱材接着工程で上記の粘度を有するものであるなら、その成分構成に特段の指定は要しない。そして、例えば、既存のものから選択することが可能である。
The above-mentioned environmental temperature can be taken as the "hot forging temperature" in the heating process, assuming the surface temperature of the forging material when it is removed from the heating furnace in the heat-resistant insulating material bonding process. Therefore, the viscosity of the glass lubricant can be taken as the viscosity at the above-mentioned hot forging temperature. This viscosity can be measured by selecting from the following two methods. One is a method in which a thin flat plate is immersed in molten glass and vibrated, the viscosity is calculated from the vibration amplitude, and the viscosity is measured while decreasing the temperature from a high-temperature range where the viscosity is low. The other is a method in which the viscosity is calculated from the height and deformation speed of the sample when pressure is applied to a solidified cylindrical sample with parallel plates, and the viscosity is measured while increasing the temperature from a low-temperature range where the viscosity is high.
The glass lubricant according to the present invention does not need to be specifically specified in terms of its composition as long as it has the above-mentioned viscosity in the heat-resistant insulating material bonding process. For example, it can be selected from existing lubricants.
＜耐熱断熱材の前記鍛造用素材と接着する面に、ガラス粒子を付着させる方法＞
二つ目の方法は、前記耐熱断熱材の前記鍛造用素材と接着する面に、ガラス粒子を付着させておき、所定の場所に耐熱断熱材を接着させることである。これは、本発明が選択的に採用できる方法である。この方法はガラス粒子が鍛造用素材表面の保有熱で軟化して接着させるものであるため、熱間鍛造温度が高いＮｉ基超耐熱合金等の熱間鍛造への適用が有効である。なお、耐熱断熱材にガラス粒子を付着させる方法としては、例えば、前記耐熱断熱材の前記鍛造用素材と接着する面にガラス粒子を散布する方法、ガラス粒子を含んだ液状体にして、これを塗布や噴霧（スプレー塗布）する方法がある。このうち、液状体を塗布や噴霧（スプレー塗布）する方法を選択した場合、ガラス粒子を付着させた耐熱断熱材を乾燥させておくのが良い。液状体を噴霧させる方法は、耐熱断熱材の前記鍛造用素材と接着する面に均一にガラス粒子を付着させることができ、特に好ましい。
なお、もちろん、上記の「ガラス潤滑剤被覆工程」に「耐熱断熱材の前記鍛造用素材と接着する面に、ガラス粒子を付着させる方法」を組み合わせても差し支えない。
<Method of Adhering Glass Particles to the Surface of the Heat-Resistant Insulating Material That Will Be Adhered to the Forging Material>
The second method is to attach glass particles to the surface of the heat-resistant insulating material that is to be bonded to the forging material, and then to bond the heat-resistant insulating material to a predetermined location. This is a method that can be selectively adopted by the present invention. In this method, the glass particles are softened by the heat retained on the surface of the forging material to be bonded, and therefore, it is effective to apply it to hot forging of Ni-based superalloys and the like, which have high hot forging temperatures. In addition, as a method for attaching glass particles to a heat-resistant insulating material, for example, a method of scattering glass particles on the surface of the heat-resistant insulating material that is to be bonded to the forging material, and a method of making a liquid containing glass particles and applying or spraying (spray application) this. Among these, when the method of applying or spraying (spray application) the liquid is selected, it is preferable to dry the heat-resistant insulating material to which the glass particles are attached. The method of spraying the liquid is particularly preferable because it allows the glass particles to be uniformly attached to the surface of the heat-resistant insulating material that is to be bonded to the forging material.
Of course, the above-mentioned "glass lubricant coating process" may be combined with the "method of adhering glass particles to the surface of the heat-resistant insulating material that is to be bonded to the forging material".
前記耐熱断熱材は無機繊維であることが好ましい。なお、本発明で言う「無機繊維」とは、ガラス繊維、セラミック繊維などを含み、断熱性に優れるセラミック繊維を選択するのが好ましい。セラミック繊維の中でも、例えば、ＫＡＯＷＯＯＬ（登録商標：以後「カオウール」と記す）などであれば、入手のしやすさや安価なことから特に好ましい。無機繊維の耐熱断熱材であれば、鍛造用素材の表面粗さが多少粗くとも、上記のガラス潤滑剤による接着剤の効果と相まって、その表面形状に沿って接着することが容易になるし、繊維が鍛造用素材表面の凹凸に引っかかりやすく、また、軽量であることから、例えば、鍛造用素材側面に接着させることも容易である。
また、本発明のように、加熱炉から取り出した鍛造用素材の少なくともその表面の一部にカオウールを接着させると、熱間鍛造初期にもカオウールがそのまま維持され、熱間鍛造中の熱間鍛造用素材の温度低下も抑制できる。従来例のように、加熱炉装入前からカオウールを配置しておくと、温度と時間の関係によるが、熱間鍛造を行うための搬送時に、簡単に破砕されるような状態となる。
The heat-resistant insulating material is preferably an inorganic fiber. In the present invention, the term "inorganic fiber" includes glass fiber, ceramic fiber, etc., and it is preferable to select ceramic fiber having excellent insulating properties. Among ceramic fibers, for example, KAOWOOL (registered trademark: hereinafter referred to as "KAOWOOL") is particularly preferable because of its ease of availability and low cost. If the heat-resistant insulating material is an inorganic fiber, even if the surface roughness of the forging material is somewhat rough, it is easy to adhere along the surface shape, combined with the adhesive effect of the above-mentioned glass lubricant, and the fiber is easily caught by the unevenness of the surface of the forging material, and since it is lightweight, it is easy to adhere to the side surface of the forging material, for example.
In addition, as in the present invention, when the Kao wool is attached to at least a part of the surface of the forging material removed from the heating furnace, the Kao wool is maintained as it is even in the early stage of hot forging, and the temperature drop of the hot forging material during hot forging can be suppressed. If the Kao wool is placed before the material is charged into the heating furnace as in the conventional example, depending on the relationship between temperature and time, the material will be easily crushed during transportation for hot forging.
＜熱間鍛造工程＞
前述の熱間鍛造用素材を用いて、金型、金敷、工具の何れかを用いて、前記熱間鍛造用素材の一部または全体を圧縮して所定の形状に成形する。用いる鍛造装置は、難加工性合金であっても、所定の形状に成形可能な鍛造荷重が数千トン以上の大型の熱間鍛造装置であることが好ましい。
また、本発明において、前記熱間鍛造工程は自由鍛造であることが好ましい。自由鍛造を行うときの熱間鍛造用素材は重量も大きく、大気中に放熱する面積も広く、加工量も大きい。そのため、耐熱断熱材を接着させて、熱間鍛造用素材の温度低下抑制の効果が大きい。この場合、前述のように、例えば、７１８合金やワスパロイ等の熱間鍛造可能な温度域がやや広い一般的なＮｉ基合金を熱間鍛造するのであれば、前記自由鍛造で前記金型、金敷、工具の何れかに接触しない鍛造用素材の自由変形部分の少なくともその表面の一部に、前記耐熱断熱材を接着させておくのが好ましい。
<Hot forging process>
The above-mentioned hot forging material is compressed in part or in whole into a desired shape using a die, anvil, or tool. The forging device used is preferably a large hot forging device with a forging load of several thousand tons or more that can form even a difficult-to-work alloy into a desired shape.
In the present invention, the hot forging step is preferably free forging. When performing free forging, the hot forging material is heavy, has a large area for dissipating heat into the atmosphere, and is processed in a large amount. Therefore, by bonding the heat-resistant insulating material, the effect of suppressing the temperature drop of the hot forging material is large. In this case, as described above, for example, if a general Ni-based alloy such as 718 alloy or Waspaloy, which has a relatively wide temperature range for hot forging, is hot forged, it is preferable to bond the heat-resistant insulating material to at least a part of the surface of the free deformation part of the forging material that does not contact any of the die, anvil, or tool during the free forging.
実施例として、本発明を詳しく説明する、なお、以下の実施例で示す本発明例の測定温度については、耐熱断熱材が接着されていない部分や熱間鍛造中や熱間鍛造終了後に一部が剥離した部分を中心に測定したものである。
実施例１
加熱前素材として、７１８合金（Ｃｒ１８．５質量％）及びワスパロイ合金（Ｃｒ１９．５質量％）の他、Ｃｒ１３．５質量％、Ｃｏ２５．０質量％、Ｍｏ２．８質量％、Ｗ１．２質量％、Ｔｉ６．２質量％、Ａｌ２．３質量％、Ｃ０．０１５質量％、Ｂ０．０１５質量％、Ｚｒ０．０３質量％、残部Ｎｉ及び不可避的不純物でなる、γ’相をおおよそ４９．５体積％含む、γ’高含有Ｎｉ基合金（以下、合金Ａ）を用意した。前記加熱前素材は、何れもインゴットを所定の寸法に機械加工したもので、その表面は粗仕上げ相当の表面粗さとした。なお、熱間自由鍛造による据込鍛造を行うため、Ｌ／Ｄを３以下としたものを加熱前素材とした。
The present invention will be described in detail with reference to the following examples. Note that the measured temperatures of the examples of the present invention shown in the following examples were measured mainly in the areas where the heat-resistant insulation material was not attached and in the areas where some of the heat-resistant insulation material peeled off during or after hot forging.
Example 1
As pre-heating materials, 718 alloy (Cr 18.5% by mass) and Waspaloy alloy (Cr 19.5% by mass) were prepared, as well as 13.5% by mass of Cr, 25.0% by mass of Co, 2.8% by mass of Mo, 1.2% by mass of W, 6.2% by mass of Ti, 2.3% by mass of Al, 0.015% by mass of C, 0.015% by mass of B, 0.03% by mass of Zr, the balance being Ni and unavoidable impurities, and a γ'-rich Ni-based alloy (hereinafter, alloy A) was prepared. The pre-heating materials were all machined from ingots to a predetermined dimension, and the surfaces had a surface roughness equivalent to that of a rough finish. In addition, in order to perform upset forging by hot free forging, the pre-heating materials were those with an L/D of 3 or less.
加熱工程に先立って、ガラス潤滑剤被覆工程として、２００℃以下の加熱前素材の時点で、その両側端面（金敷または工具に接触する面）にガラス潤滑剤をおおよそ５０～２００μｍの厚さで被覆した（ガラス潤滑剤被覆工程）。用いたガラス潤滑剤の粘度を、上述の要領に従って振動式粘度計で測定したところ、１１００℃および１１５０℃（つまり、下記の熱間鍛造温度）のときの粘度が、それぞれ１×１０４Ｐａ・ｓおよび３×１０３Ｐａ・ｓであった。この加熱前素材を加熱炉中で所定の熱間鍛造温度に加熱した（加熱工程）。このときの酸素濃度は２～８％に制御した。加熱の温度（熱間鍛造温度）は、合金Ａ及び７１８合金が１１００℃、ワスパロイ合金が１１５０℃とし、保持時間を２～９時間とした。熱間鍛造温度までの昇温時間は、おおよそ８時間であり、表面全面を耐熱断熱材で包み込むような従来例と比較して１０時間以上早く所定の温度に昇温することができた。
次に、加熱炉からマニピュレータで取り出した鍛造用素材１の両側端面の表面に耐熱断熱材１１を接着させて熱間鍛造用素材２とした（耐熱断熱材接着工程）。耐熱断熱材はカオウール（無機繊維）とし、図１で示すように金敷または工具に接触する面に接着させ、熱間鍛造用素材の温度低下の抑制と、金敷または工具と接触することによる抜熱の抑制を行った。そして、予め被覆したガラス潤滑剤により、カオウールと鍛造用素材とは短時間で且つ、問題なく接着が完了したため、通常、載置までに低下する温度と比較しておおよそ５～１０℃程度の温度が低下しただけで、熱間鍛造には支障がないものと判断した。
Prior to the heating step, as a glass lubricant coating step, both end faces (surfaces in contact with anvils or tools) of the pre-heated material at 200°C or less were coated with a glass lubricant to a thickness of approximately 50 to 200 μm (glass lubricant coating step). When the viscosity of the glass lubricant used was measured with a vibration viscometer according to the above-mentioned procedure, the viscosity at 1100°C and 1150°C (i.e., the hot forging temperature described below) was 1×10 4 Pa·s and 3×10 3 Pa·s, respectively. This pre-heated material was heated to a predetermined hot forging temperature in a heating furnace (heating step). The oxygen concentration at this time was controlled to 2 to 8%. The heating temperature (hot forging temperature) was 1100°C for alloy A and 718 alloy, and 1150°C for Waspaloy alloy, and the holding time was 2 to 9 hours. The time required to heat up to the hot forging temperature was approximately 8 hours, which was 10 hours or more faster than in the conventional example in which the entire surface was wrapped in heat-resistant insulating material.
Next, heat-resistant insulating
前記の熱間鍛造用素材を用いて、熱間自由鍛造による据込鍛造を行った。用いた熱間鍛造装置の下金敷上に熱間鍛造用素材を載置し、熱間鍛造用素材の上側端面に据込鍛造用の工具を載置した後に、加圧能力が４０００ｔｏｎの熱間鍛造装置を用いて押圧する自由鍛造を行い、次工程の熱間鍛造に用いる荒地（熱間鍛造材３）を作製した（熱間鍛造工程）。前記下金敷と据込鍛造用工具が熱間鍛造用素材に接触している部分以外は、自由変形領域であった。鍛造開始温度はおおよそ１０００℃であり、熱間鍛造中の鍛造温度はおおよそ９５０～９８０℃であった。前記のように、下金敷と接触する部分と、上側端面側の据込鍛造用工具が接触する部分には、カオウールによって抜熱が抑制されていたため、熱間鍛造材の端部のシワ疵（割れ）などの表面欠陥の発生は殆ど生じなかった。Using the above-mentioned hot forging material, upset forging was performed by hot free forging. The hot forging material was placed on the lower anvil of the hot forging device used, and the upset forging tool was placed on the upper end surface of the hot forging material. After that, free forging was performed by pressing using a hot forging device with a pressure capacity of 4000 tons, and a rough surface (hot forged material 3) to be used in the next process of hot forging was produced (hot forging process). The area other than the part where the lower anvil and the upset forging tool were in contact with the hot forging material was a free deformation area. The forging start temperature was approximately 1000°C, and the forging temperature during hot forging was approximately 950 to 980°C. As described above, heat dissipation was suppressed by the Kao wool in the part in contact with the lower anvil and in the part in contact with the upset forging tool on the upper end face side, so there was almost no occurrence of surface defects such as wrinkles (cracks) on the ends of the hot forged material.
実施例２
ワスパロイ合金を用いて、耐熱断熱材を接着させたもの（本発明例１）と、耐熱断熱材を接着しないもの（比較例１）について、熱間鍛造中の温度変化と熱間鍛造材の疵（割れ）の発生具合を比較した。
用いた鍛造前素材は、何れもインゴットを所定の寸法に機械加工したもので、その表面は粗仕上げ相当の表面粗さとした。なお、Ｌ／Ｄを１．５以下としたものを加熱前素材として熱間自由鍛造による据込鍛造を行った。
Example 2
The temperature change during hot forging and the occurrence of defects (cracks) in the hot forged material were compared for a material in which a heat-resistant insulating material was bonded using Waspaloy alloy (Example 1 of the present invention) and a material in which a heat-resistant insulating material was not bonded (Comparative Example 1).
The pre-forging materials used were all machined ingots to a specified size, and their surfaces had a surface roughness equivalent to that of rough finishing. Note that the pre-heating materials with an L/D ratio of 1.5 or less were subjected to upset forging by hot free forging.
加熱工程に先立って、ガラス潤滑剤被覆工程として、本発明例１の加熱前素材の両側端面（金敷または工具に接触する面）及び耐熱断熱材を接着させる外周面部分にガラス潤滑剤をおおよそ５０～２００μｍの厚さで被覆した（ガラス潤滑剤被覆工程）。ガラス潤滑剤は、実施例１で用いたものとした（１１５０℃（つまり、下記の熱間鍛造温度）のときの粘度３×１０３Ｐａ・ｓ）。この加熱前素材を加熱炉中で所定の熱間鍛造温度に加熱した（加熱工程）。このときの酸素濃度は２～８％に制御した。加熱の温度（熱間鍛造温度）は１１５０℃とし、保持時間を２～４時間とした。鍛造温度までの昇温時間は、おおよそ８時間であった。
次に、図２に示すように、耐熱断熱材１１として長さの異なるカオウール（無機繊維）２枚（１１Ａが長く、１１Ｂが短い）をクロス状に重ね、加熱炉からマニピュレータで取り出した本発明例１の鍛造用素材１を重ねた部分に載置し、無機断熱材を黒矢印の方向に折り曲げながら、鍛造用素材の両側端面及び外周面の表面に耐熱断熱材を接着させた。耐熱断熱材１１Ｂは長さが短く、鍛造用素材の全高さ付近までの長さであり、長さの長い耐熱断熱材１１Ａは、鍛造用素材の上側端面部分で重ね、鍛造用素材のほぼ表面全体を包んで熱間鍛造用素材とした（耐熱断熱材接着工程）。これにより、熱間鍛造用素材の温度低下の抑制と、金敷または工具と接触することによる抜熱の抑制、マニピュレータの把持部と接触することによる抜熱の抑制を行った。そして、予め被覆したガラス潤滑剤に加えて、鍛造用素材と接着するカオウールの面へのガラス粒子の付着により、カオウールと鍛造用素材とは短時間で且つ、問題なく接着が完了したため、通常、載置までに低下する温度と比較しておおよそ５～１０℃程度の温度が低下しただけで、熱間鍛造には支障がないものと判断した。なお、比較例１の鍛造用素材には、耐熱断熱材の被覆は行わなかった。
Prior to the heating step, as a glass lubricant coating step, both end faces (surfaces in contact with anvils or tools) of the pre-heated material of the present invention example 1 and the outer peripheral surface portion to which the heat-resistant insulating material is to be bonded were coated with a glass lubricant to a thickness of approximately 50 to 200 μm (glass lubricant coating step). The glass lubricant was the same as that used in Example 1 (viscosity 3×10 3 Pa·s at 1150° C. (i.e., hot forging temperature described below). This pre-heated material was heated to a predetermined hot forging temperature in a heating furnace (heating step). The oxygen concentration at this time was controlled to 2 to 8%. The heating temperature (hot forging temperature) was 1150° C., and the holding time was 2 to 4 hours. The temperature rise time to the forging temperature was approximately 8 hours.
Next, as shown in Fig. 2, two sheets of Kao wool (inorganic fiber) with different lengths (11A is long and 11B is short) were stacked in a cross shape as the heat-resistant insulating
前記の熱間鍛造用素材を用いて、熱間自由鍛造を行った。用いた熱間鍛造装置の下金敷上に熱間鍛造用素材を載置し、熱間鍛造用素材の上側端面に据込鍛造用の工具を載置した後に、加圧能力が１００００ｔｏｎの熱間鍛造装置を用いて押圧する自由鍛造を行い、次工程の熱間鍛造に用いる荒地（熱間鍛造材）を作製した（熱間鍛造工程）。前記下金敷と据込鍛造用工具が熱間鍛造用素材に接触している部分以外は、自由変形領域であった。鍛造開始温度はおおよそ１０５０℃であり、熱間鍛造中の鍛造温度はおおよそ１０００℃であった。
据込鍛造直後の熱間鍛造用素材の温度を放射温度計で測定したところ、本発明例１ではおおよそ１０９０～１１２０℃であり、比較例１は９５０～９９０℃であった。本発明例１の方が熱間鍛造中の温度を約１００℃以上高く保持できた。作製した熱間鍛造材の割れの状況を確認したところ、本発明例１の熱間鍛造材には目視で殆ど割れの発生が確認できなかったが、比較例１の熱間鍛造材には、金敷または工具と接触する鍛造用素材の両側端面やマニピュレータで把持する鍛造用素材側面で目視で確認できるだけの割れが確認できた。
Using the above-mentioned hot forging material, hot free forging was performed. The hot forging material was placed on the lower die of the hot forging device used, and a tool for upset forging was placed on the upper end surface of the hot forging material. After that, free forging was performed by pressing using a hot forging device with a pressurizing capacity of 10,000 tons, and a rough area (hot forged material) to be used in the next hot forging process was prepared (hot forging process). The area other than the part where the lower die and the upset forging tool were in contact with the hot forging material was a free deformation area. The forging start temperature was approximately 1050°C, and the forging temperature during hot forging was approximately 1000°C.
When the temperature of the hot forging material immediately after upset forging was measured with a radiation thermometer, it was approximately 1090 to 1120 ° C. in Example 1 of the present invention, and 950 to 990 ° C. in Comparative Example 1. The temperature during hot forging was maintained at about 100 ° C. higher in Example 1 of the present invention. When the cracking state of the hot forged material produced was confirmed, the hot forged material of Example 1 of the present invention had almost no cracking by visual inspection, but the hot forged material of Comparative Example 1 had cracks that could be visually confirmed on both end faces of the forging material that contacted the anvil or tool and on the side of the forging material that was held by the manipulator.
実施例３
ワスパロイ合金を用いて、耐熱断熱材を接着させたもの（本発明例２）と、耐熱断熱材を接着しないもの（比較例２）について、鍛伸中の温度変化と熱間鍛造材の疵（割れ）の発生具合を比較した。
用いた加熱前素材は、据込鍛造後の素材を所定の寸法に機械加工したもので、その表面は粗仕上げ相当の表面粗さとした。
Example 3
The temperature changes during forging and the occurrence of defects (cracks) in the hot forged material were compared for a material in which heat-resistant insulation material was bonded using Waspaloy alloy (Example 2 of the present invention) and a material in which heat-resistant insulation material was not bonded (Comparative Example 2).
The pre-heated material used was a material that had been upset forged and machined to a specified size, and its surface had a surface roughness equivalent to that of a rough finish.
加熱工程に先立って、ガラス潤滑剤被覆工程として、本発明例２の加熱前素材の両側端面及び耐熱断熱材を接着させる部分にガラス潤滑剤をおおよそ５０～２００μｍの厚さで被覆した（ガラス潤滑剤被覆工程）。ガラス潤滑剤は、実施例１で用いたものとした（１１５０℃（つまり、下記の熱間鍛造温度）のときの粘度３×１０３Ｐａ・ｓ）。この加熱前素材を加熱炉中で所定の熱間鍛造温度に加熱した（加熱工程）。このときの酸素濃度は２～８％に制御した。加熱の温度は１１５０℃とし、保持時間を２～４時間とした。鍛造温度までの昇温時間は、おおよそ８時間であった。
次に、図３に示すように、耐熱断熱材１１を準備し、加熱炉からマニピュレータで取り出した本発明例２の鍛造用素材１を耐熱断熱材１１上に載置し、耐熱断熱材を黒矢印の方向に曲げながら、外周面の表面に耐熱断熱材を接着させて熱間鍛造用素材とした（耐熱断熱材接着工程）。耐熱断熱材はカオウール（無機繊維）とし、図３で示すように外周面（鍛造用素材の自由変形部分）に接着させ、熱間鍛造用素材の温度低下の抑制と、マニピュレータの把持部と接触することによる抜熱の抑制を行った。そして、予め被覆したガラス潤滑剤に加えて、鍛造用素材と接着するカオウールの面へのガラス粒子の付着により、カオウールと鍛造用素材とは短時間で且つ、問題なく接着が完了したため、通常、載置までに低下する温度と比較しておおよそ５～１０℃程度の温度が低下しただけで、熱間鍛造には支障がないものと判断した。なお、比較例２の鍛造用素材には、耐熱断熱材の被覆は行わなかった。
Prior to the heating step, as a glass lubricant coating step, both end faces of the pre-heated material of the present invention example 2 and the part where the heat-resistant heat insulating material is to be bonded were coated with a glass lubricant to a thickness of approximately 50 to 200 μm (glass lubricant coating step). The glass lubricant was the same as that used in Example 1 (viscosity 3×10 3 Pa·s at 1150° C. (i.e., the hot forging temperature described below). This pre-heated material was heated to a predetermined hot forging temperature in a heating furnace (heating step). The oxygen concentration at this time was controlled to 2 to 8%. The heating temperature was 1150° C., and the holding time was 2 to 4 hours. The temperature rise time to the forging temperature was approximately 8 hours.
Next, as shown in Fig. 3, a heat-resistant insulating
前記の熱間鍛造用素材を用いて、熱間鍛伸を行った。熱間鍛造用素材の側面を熱間鍛造装置の下金敷と上金敷で挟み、加圧能力が４０００ｔｏｎの熱間鍛造装置を用いて押圧する鍛伸鍛造を行い、次工程の熱間鍛造に用いる荒地（熱間鍛造材）を作製した（熱間鍛造工程）。鍛造開始温度は被覆されてない部位でおおよそ１０５０℃であり、熱間鍛造中の被覆がはがれた場所の鍛造素材温度はおおよそ１０８０～１０２０℃であった。
熱間鍛造終了直後の熱間鍛造用素材の温度を放射温度計で測定したところ、本発明例２では９５０～９８０℃であり、比較例２は９００～９５０℃であった。本発明例２の方が、熱間鍛造中の温度を約５０～８０℃高く保持できた。作製した熱間鍛造材の割れの状況を確認したところ、本発明例２の熱間鍛造材には目視で殆ど割れの発生が確認できなかったが、比較例２の熱間鍛造材には、目視で確認できるだけの割れが全体的に確認できた。
The hot forging material was used to perform hot forging and stretching. The side of the hot forging material was sandwiched between the lower and upper anvils of a hot forging device, and a forging and stretching process was performed by pressing the material using a hot forging device with a pressurizing capacity of 4000 tons, to prepare a rough material (hot forged material) to be used in the next hot forging process (hot forging process). The forging start temperature was approximately 1050°C in the uncoated area, and the forging material temperature at the location where the coating was peeled off during hot forging was approximately 1080 to 1020°C.
When the temperature of the hot forging material immediately after the hot forging was completed was measured with a radiation thermometer, it was 950 to 980 ° C in Example 2 of the present invention, and 900 to 950 ° C in Comparative Example 2. In Example 2 of the present invention, the temperature during hot forging was maintained about 50 to 80 ° C higher. When the cracking state of the hot forged material produced was confirmed, the hot forged material of Example 2 of the present invention had almost no cracking with the naked eye, but the hot forged material of Comparative Example 2 had cracks that could be visually confirmed overall.
以上、説明する本発明の熱間鍛造材の製造方法によれば、熱間鍛造用素材として難加工性合金を用いても、割れなどの不良を防止しつつ、効率よく熱間鍛造を行うことが可能であることが分かる。 According to the manufacturing method for hot forged material of the present invention described above, it is possible to efficiently perform hot forging while preventing defects such as cracks, even when a difficult-to-work alloy is used as the material for hot forging.
１ 鍛造用素材
２ 熱間鍛造用素材
３ 熱間鍛造材
１１ 耐熱断熱材
1 Forging
Claims (4)
前記加熱炉から取り出した鍛造用素材の少なくともその表面の一部に、耐熱断熱材を接着させて熱間鍛造用素材とする耐熱断熱材接着工程と、
金型、金敷、工具の何れかを用いて、前記熱間鍛造用素材の一部または全体を圧縮して所定の形状に成形する熱間鍛造工程と、
を含み、
更に、前記加熱前素材表面の、少なくとも前記耐熱断熱材を接着する部分にはガラス潤滑剤を被覆するガラス潤滑剤被覆工程と、
を含み、
前記ガラス潤滑剤が、前記耐熱断熱材接着工程において１０２～１０７Ｐａ・ｓの粘度を有するものであることを特徴とする熱間鍛造材の製造方法。 A heating process in which a pre-heated material to be hot forged is heated to a hot forging temperature in a heating furnace;
A heat-resistant insulating material bonding process for bonding a heat-resistant insulating material to at least a part of the surface of the forging material removed from the heating furnace to prepare a hot forging material;
A hot forging process in which a part or the whole of the hot forging material is compressed and formed into a predetermined shape using a die, an anvil, or a tool;
Including,
Furthermore, a glass lubricant coating process is performed to coat at least a portion of the surface of the pre-heated material to which the heat-resistant insulating material is to be bonded with a glass lubricant.
Including,
A method for producing a hot forged material, characterized in that the glass lubricant has a viscosity of 10 2 to 10 7 Pa·s in the heat-resistant insulating material bonding step.
The method for producing a hot forged material according to claim 1, wherein the heat resistant and insulating material is inorganic fiber.
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| JP2014508857A (en) | 2011-01-17 | 2014-04-10 | エイティーアイ・プロパティーズ・インコーポレーテッド | Improving hot workability of metal alloys through surface coating |
| JP2014210288A (en) | 2013-04-01 | 2014-11-13 | 日立金属株式会社 | Hot forging method |
| JP2017148817A (en) | 2016-02-22 | 2017-08-31 | 株式会社神戸製鋼所 | Hot forging method and manufacturing method of hot forged product |
| JP2018164925A (en) | 2017-03-28 | 2018-10-25 | 日立金属株式会社 | Method for manufacturing forged product |
| WO2021182606A1 (en) | 2020-03-13 | 2021-09-16 | 日立金属株式会社 | Method for manufacturing hot-forged member |
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| JP2014508857A (en) | 2011-01-17 | 2014-04-10 | エイティーアイ・プロパティーズ・インコーポレーテッド | Improving hot workability of metal alloys through surface coating |
| JP2014210288A (en) | 2013-04-01 | 2014-11-13 | 日立金属株式会社 | Hot forging method |
| JP2017148817A (en) | 2016-02-22 | 2017-08-31 | 株式会社神戸製鋼所 | Hot forging method and manufacturing method of hot forged product |
| JP2018164925A (en) | 2017-03-28 | 2018-10-25 | 日立金属株式会社 | Method for manufacturing forged product |
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