JP2023180123A - Production method of steel material for hot die - Google Patents
Production method of steel material for hot die Download PDFInfo
- Publication number
- JP2023180123A JP2023180123A JP2022093249A JP2022093249A JP2023180123A JP 2023180123 A JP2023180123 A JP 2023180123A JP 2022093249 A JP2022093249 A JP 2022093249A JP 2022093249 A JP2022093249 A JP 2022093249A JP 2023180123 A JP2023180123 A JP 2023180123A
- Authority
- JP
- Japan
- Prior art keywords
- steel
- heat treatment
- hot
- treatment step
- steel material
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 104
- 239000010959 steel Substances 0.000 title claims abstract description 104
- 239000000463 material Substances 0.000 title claims abstract description 60
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 10
- 238000010438 heat treatment Methods 0.000 claims abstract description 71
- 238000002360 preparation method Methods 0.000 claims abstract description 4
- 238000000034 method Methods 0.000 claims description 23
- 238000005242 forging Methods 0.000 abstract description 17
- 238000005336 cracking Methods 0.000 description 20
- 238000001816 cooling Methods 0.000 description 13
- 229910052739 hydrogen Inorganic materials 0.000 description 6
- 239000001257 hydrogen Substances 0.000 description 6
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 5
- 230000007547 defect Effects 0.000 description 5
- 241000519995 Stachys sylvatica Species 0.000 description 4
- 206010044625 Trichorrhexis Diseases 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000000879 optical micrograph Methods 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 238000010313 vacuum arc remelting Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- JZQOJFLIJNRDHK-CMDGGOBGSA-N alpha-irone Chemical compound CC1CC=C(C)C(\C=C\C(C)=O)C1(C)C JZQOJFLIJNRDHK-CMDGGOBGSA-N 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000010309 melting process Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Landscapes
- Heat Treatment Of Articles (AREA)
Abstract
Description
本発明は、熱間金型用鋼素材の製造方法に関するものである。 The present invention relates to a method of manufacturing a steel material for hot molds.
ＳＫＤ６１やＳＫＴ４等に代表されるＪＩＳで規定される熱間金型用鋼は、汎用性の高い材料として知られている。これらの熱間金型用鋼は成分、金属組織、機械的特性を最適化するため、多くの改良材が提案されている。これらの素材は、本鋼の成分組成を有した溶湯を鋳造して鋼塊とし、これに熱間加工と熱処理を行って製造される。
この熱間金型用鋼を製造する場合において、内部欠陥を防止する必要がある。特に熱間で用いる金型が大型化すると、割れに対する欠陥防止が重要になる。
Steels for hot work molds specified by JIS, such as SKD61 and SKT4, are known as highly versatile materials. Many improved materials have been proposed to optimize the composition, metal structure, and mechanical properties of these steels for hot work molds. These materials are produced by casting a molten metal having the composition of the present steel into a steel ingot, and subjecting the ingot to hot working and heat treatment.
When manufacturing this hot die steel, it is necessary to prevent internal defects. In particular, as molds used in hot processes become larger, prevention of cracking defects becomes important.
上述した欠陥のうち、微小な空洞が形成される内部欠陥として「毛割れ」或いは「白点」と呼ばれるものがある。この毛割れや白点は割れの起点となることから、毛割れや白点抑制の検討が以前よりなされている。なお、前述の「毛割れ」と「白点」は同じ欠陥であることから、以後は単に「毛割れ」と記す。この毛割れを防止する方法としては、例えば、特開２０２１－３０２４７号公報（特許文献１）にはエレクトロスラグ再溶解（以後、ＥＳＲ）のプリメルトフラックスを調整する方法、特開２０１１－９９１５１号公報（特許文献２）にはＲＨ脱ガス処理時の予備工程を制御して鋼塊の毛割れを防止している。
また、特開２０００－１９２１９２号公報（特許文献３）には成分調整により、毛割れの発生を防止している。更に特開平１１－１８１５１７（特許文献４）では、鋼製品を常温より加熱し、２００～３００℃又は４００～５００℃の間で少なくとも（Ｄ・ｔ）１／２＝（製品最小厚みの１／２）の関係を満足する時間ｔ以上（ただし、Ｄはα鉄中の水素の拡散係数）の間、保定して脱水素する発明が有る。
Among the above-mentioned defects, there are internal defects in which minute cavities are formed called "hair cracks" or "white spots." Since these hair cracks and white spots are the starting point of cracks, studies have been conducted for some time to suppress hair splits and white spots. Note that since the above-mentioned "hair cracks" and "white spots" are the same defect, they will be simply referred to as "hair cracks" hereinafter. As a method for preventing hair cracking, for example, Japanese Patent Application Laid-Open No. 2021-30247 (Patent Document 1) discloses a method of adjusting premelt flux of electroslag remelting (hereinafter referred to as ESR), and Japanese Patent Application Laid-Open No. 2011-99151 In the publication (Patent Document 2), hair cracking of the steel ingot is prevented by controlling the preliminary process during RH degassing treatment.
Furthermore, Japanese Patent Laid-Open No. 2000-192192 (Patent Document 3) discloses that the occurrence of hair breakage is prevented by adjusting the ingredients. Furthermore, in JP-A-11-181517 (Patent Document 4), a steel product is heated from room temperature to at least (D.t)1/2=(1/2 of the minimum thickness of the product) between 200 and 300°C or between 400 and 500°C. There is an invention in which hydrogen is retained and dehydrogenated for a time t or longer that satisfies the relationship 2) (where D is the diffusion coefficient of hydrogen in α-iron).
図２に示すものは、ＥＳＲを適用したＪＩＳ－ＳＫＤ６１改良鋼の断面に見られた毛割れの断面光学顕微鏡写真である。このような毛割れが多く発生したものは、水素含有量がやや高めであって、これを大型の金型として使用した場合、毛割れを起点とする割れの発生が懸念される。このように、溶解工程後に毛割れが残留した場合、前述の特許文献１乃至３の方法では毛割れを無害化することは困難である。
また、特許文献４の脱水素方法は、熱間加工や熱処理を経て機械的性質を付与した素材に対して、その機械的性質を維持しつつ脱水素を行うものであり、比較的厚みが薄い最終形状まで加工した素材に対しての処理を提案するものである。しかしながら、前述のように金型の大型化による鋼塊の大径化、それに伴って鋼片の厚さも厚くなると、鋼塊または熱間鍛造の初期段階での毛割れ防止を行っておかないと、熱間加工やそれに伴う冷却工程での毛割れを起点とする割れを生じる場合がある。
そこで本発明の目的は、鋼塊或いは熱間鍛造の段階で毛割れの発生を防止可能な熱間金型用鋼素材の製造方法を提供することである。
What is shown in FIG. 2 is a cross-sectional optical micrograph of hair cracks observed in the cross section of JIS-SKD61 improved steel to which ESR has been applied. Products with a lot of hair cracking have a slightly high hydrogen content, and if this is used as a large mold, there is a concern that cracks may start from the hair cracks. As described above, when hair cracks remain after the dissolution step, it is difficult to render the hair cracks harmless using the methods of Patent Documents 1 to 3 described above.
In addition, the dehydrogenation method of Patent Document 4 dehydrogenates a material that has been given mechanical properties through hot working or heat treatment while maintaining its mechanical properties, and the material is relatively thin. This proposal proposes processing for materials that have been processed to their final shape. However, as mentioned above, as the diameter of the steel ingot increases due to the enlargement of the mold, and the thickness of the steel billet increases accordingly, it is necessary to prevent hair cracking at the initial stage of the steel ingot or hot forging. In some cases, cracks may occur due to hair cracking during hot processing and the accompanying cooling process.
SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a steel material for hot molds that can prevent hair cracking from occurring during the steel ingot or hot forging stage.
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、熱間金型用鋼の鋼塊または該鋼塊を熱間加工した中間鋼材を準備する素材準備工程と、前記鋼塊または該鋼塊を熱間加工した中間鋼材を熱処理する熱処理工程とを含み、前記熱処理工程は３００～５５０℃で１２時間以上である熱間金型用鋼素材の製造方法である。
好ましくは、前記熱処理工程に続いて、熱処理工程後の鋼塊または中間鋼材の中心部温度が６００～９５０℃となるように、鋼塊または中間鋼材を加熱する第２熱処理工程を更に含む。
好ましくは、前記鋼塊は再溶解後の鋼塊である。
The present invention has been made in view of the above-mentioned problems.
That is, the present invention includes a material preparation step of preparing a steel ingot of hot mold steel or an intermediate steel material obtained by hot working the steel ingot, and heat treating the steel ingot or an intermediate steel material obtained by hot working the steel ingot. The method includes a heat treatment step, and the heat treatment step is at 300 to 550° C. for 12 hours or more.
Preferably, following the heat treatment step, the method further includes a second heat treatment step of heating the steel ingot or intermediate steel material so that the temperature at the center of the steel ingot or intermediate steel material after the heat treatment step is 600 to 950°C.
Preferably, the steel ingot is a remelted steel ingot.
本発明によれば、溶解後の鋼塊或いは熱間鍛造の段階で毛割れの発生を防止することができる。 According to the present invention, it is possible to prevent hair cracking from occurring in the steel ingot after melting or at the stage of hot forging.
本発明が対象とする熱間金型用鋼は、ＪＩＳ Ｇ４４０４で示される「熱間金型用」の鋼及びその改良成分を有する鋼を指す。具体的な組成の範囲は、質量％で、Ｃ：０．２５～０．６０％、Ｓｉ：１．２％以下、Ｍｎ：０．９％以下、Ｃｒ：０．８～５．６％、Ｖ：０．０５～２．１０％を含み、選択的元素として、Ｎｉ：１．５～１．８％、Ｍｏ：０．３～３．０％、Ｗ：１．０～６．０％、Ｃｏ：４．０～４．５％の一種以上を含み、残部はＦｅ及び不純物の成分を有するものである。 The steel for hot molds to which the present invention is directed refers to steel for "hot molds" specified by JIS G4404 and steels having improved components thereof. The specific composition ranges are, in mass%, C: 0.25 to 0.60%, Si: 1.2% or less, Mn: 0.9% or less, Cr: 0.8 to 5.6%, Contains V: 0.05 to 2.10%, and as selective elements, Ni: 1.5 to 1.8%, Mo: 0.3 to 3.0%, W: 1.0 to 6.0%. , Co: 4.0 to 4.5%, and the remainder contains Fe and impurity components.
＜素材準備工程＞
前述した成分を有する熱間金型用鋼の鋼塊を準備する。準備する鋼塊は、少なくとも１回以上の溶解工程を経たものとする。例えば、ＥＳＲや真空アーク再溶解（ＶＡＲ）を適用した物であっても良い。熱間金型の大型化に対応するには、成分偏析を軽減可能な再溶解を適用した再溶解後の鋼塊を準備するのが好ましい。なお、本発明においては、後述する熱処理工程で毛割れの発生を防止するため、溶解工程における特別な毛割れ防止対策は必ずしも必要としない。なお、本発明は鋼塊重量が１ｔ以上の大型のものに適用することが好ましい。より好ましい重量は５ｔ以上、さらに好ましい重量は１０ｔ以上、よりさらに好ましい重量は１５ｔ以上である。
また、本発明においては、前記鋼塊を熱間加工した中間鋼材を熱処理工程用の素材としても良い。ここで言う「中間鋼材」とは、熱間鍛造により分塊した鋼片や、鋼片に対して仕上げ鍛造を施した鋼材を指す。この中間鋼材も前述した鋼塊と同様、重量が１ｔ以上の大型のものに適用する。より好ましい重量は５ｔ以上、さらに好ましい重量は１０ｔ以上、よりさらに好ましい重量は１５ｔ以上である。なお準備した熱処理工程用素材は、後述する熱処理工程に移行する前に放冷や衝風冷却により冷却してもよい。
<Material preparation process>
A steel ingot of hot mold steel having the above-mentioned components is prepared. The steel ingot to be prepared has undergone at least one melting process. For example, it may be a material to which ESR or vacuum arc remelting (VAR) is applied. In order to cope with the increase in the size of hot molds, it is preferable to prepare a steel ingot after applying remelting that can reduce component segregation. In addition, in the present invention, in order to prevent the occurrence of hair cracking in the heat treatment step described below, special measures to prevent hair cracking in the melting step are not necessarily required. Note that the present invention is preferably applied to large steel ingots having a weight of 1 t or more. A more preferable weight is 5 tons or more, an even more preferable weight is 10 tons or more, and an even more preferable weight is 15 tons or more.
Further, in the present invention, an intermediate steel material obtained by hot working the steel ingot may be used as a material for the heat treatment process. The term "intermediate steel material" as used herein refers to a steel billet that has been bloomed by hot forging, or a steel material that has been subjected to finish forging on a steel billet. Similar to the steel ingot described above, this intermediate steel material is also applied to large objects weighing 1 t or more. A more preferable weight is 5 tons or more, an even more preferable weight is 10 tons or more, and an even more preferable weight is 15 tons or more. Note that the prepared material for the heat treatment process may be cooled by air cooling or blast cooling before proceeding to the heat treatment process described later.
＜熱処理工程＞
本発明では、できるだけ上工程の段階で毛割れの発生を防止することが可能な熱処理工程を適用する。大型の鋼塊や中間鋼材に毛割れが発生すると、その加熱冷却時や熱間加工時に毛割れを起点とした割れを生じるおそれがあるため、この熱処理工程（毛割れ発生防止熱処理と記すときがある）をできるだけ上工程で適切に行うことが重要となる。
本発明の熱処理工程の熱処理条件は、３００～５５０℃で１２時間以上とする。加熱温度の範囲を３００～５５０℃としたのは、加熱温度の下限が３００℃未満であると、鋼塊や中間鋼材の割れにつながる可能性があるためである。また、加熱温度の上限が５５０℃を超えると水素拡散速度が遅くなることが考えられ、それに起因する毛割れ防止効果の低下が懸念される。加熱温度の好ましい下限は４００℃であり、好ましい加熱温度の上限は５００℃である。
また、加熱時間の範囲を１２時間以上としたのは、加熱時間の下限が１２時間未満であると、毛割れの発生に関与する水素を除去することができない傾向にあるためである。また、加熱時間の上限については、特に限定しないが、おおよそ４８時間を超えると毛割れの発生を防止する効果は飽和する傾向にあるので、例えば４８時間と設定してもよい。
なお、本発明においては、大型の鋼塊または中間鋼材を対象としているため、熱処理工程前に予備加熱を行っても良いし、熱処理工程の温度範囲内で多段の加熱や冷却を行っても良い。また、この熱処理工程のみを実施する場合、処理材を炉内に保持して自然放冷よりも緩やかに冷却する、炉冷を実施してもよい。
<Heat treatment process>
In the present invention, a heat treatment step that can prevent the occurrence of hair cracking is applied as early as possible in the upper process stage. If hair cracks occur in large steel ingots or intermediate steel materials, there is a risk of cracks starting from the hair cracks during heating, cooling, or hot processing. It is important to carry out these steps appropriately in the upper process as much as possible.
The heat treatment conditions of the heat treatment step of the present invention are 300 to 550° C. for 12 hours or more. The reason why the heating temperature range is 300 to 550°C is that if the lower limit of the heating temperature is less than 300°C, it may lead to cracking of the steel ingot or intermediate steel material. Further, if the upper limit of the heating temperature exceeds 550° C., the hydrogen diffusion rate may be slowed down, and there is a concern that the effect of preventing hair breakage may decrease due to this. A preferable lower limit of the heating temperature is 400°C, and a preferable upper limit of the heating temperature is 500°C.
Further, the reason why the range of the heating time is set to 12 hours or more is because if the lower limit of the heating time is less than 12 hours, hydrogen that is involved in the occurrence of hair cracking tends to be unable to be removed. Further, the upper limit of the heating time is not particularly limited, but if it exceeds about 48 hours, the effect of preventing hair breakage tends to be saturated, so it may be set to, for example, 48 hours.
In addition, since the present invention targets large steel ingots or intermediate steel materials, preheating may be performed before the heat treatment process, or multistage heating and cooling may be performed within the temperature range of the heat treatment process. . Further, when only this heat treatment step is performed, furnace cooling may be performed in which the treated material is held in a furnace and cooled more slowly than natural cooling.
＜第２熱処理工程＞
また、前記の熱処理工程（毛割れ発生防止熱処理）に続いて、第２熱処理工程を行っても差し支えない。第２熱処理工程は鋼塊および中間鋼材の割れをより安定して抑制することができる。この第２熱処理工程の熱処理条件は、熱処理工程後の鋼塊または中間鋼材（以下、第２熱処理用素材とも記載する）の中心部温度が６００～９５０℃となるように、第２熱処理用素材を加熱することが好ましい。第２熱処理用素材の温度を６００℃以上とすることで、割れの原因となる内部応力を十分に除去することができる傾向にある。また、第２熱処理用素材の温度を９５０℃以下とすることで、結晶粒の粗大化の抑制や、脱炭または炭素固溶量の増加に起因する冷却時の割れ抑制することができる。第２熱処理用素材の中心部温度の好ましい下限は６５０℃であり、より好ましい下限は７００℃である。また好ましい第２熱処理用素材の中心部温度の上限は９００℃であり、より好ましい上限は８５０℃である。さらに好ましくは８００℃である。ここで第２熱処理用素材の「中心部温度」は、例えばＳＫＴ４相当の厚み約５００ｍｍの直方体状中間鋼材であれば、５時間以上、好ましくは７時間以上加熱すれば中心部温度が６００～９５０℃となる傾向にある。なお、本発明においては、第２熱処理工程を適用する場合、前記熱処理工程（毛割れ発生防止熱処理）に引き続いて（連続して）行うことが好ましい。また、大型の鋼塊または鋼片に対して前記熱処理工程を適用するため、前記の第２熱処理工程前に予備加熱を行っても良い。また、この第２熱処理工程後の冷却速度は処理材を炉内に保持して自然放冷よりも緩やかに冷却する、炉冷を実施してもよい。
<Second heat treatment step>
Furthermore, following the heat treatment step (heat treatment to prevent hair cracking), a second heat treatment step may be performed. The second heat treatment step can more stably suppress cracks in the steel ingot and the intermediate steel material. The heat treatment conditions for this second heat treatment step are such that the temperature of the center of the steel ingot or intermediate steel material (hereinafter also referred to as the second heat treatment material) after the heat treatment step is 600 to 950°C. It is preferable to heat it. By setting the temperature of the second heat treatment material to 600° C. or higher, internal stress that causes cracks tends to be sufficiently removed. Further, by setting the temperature of the second heat treatment material to 950° C. or lower, it is possible to suppress coarsening of crystal grains and suppress cracking during cooling caused by decarburization or an increase in the amount of carbon solid solution. A preferable lower limit of the center temperature of the second heat treatment material is 650°C, and a more preferable lower limit is 700°C. Further, a preferable upper limit of the center temperature of the second heat treatment material is 900°C, and a more preferable upper limit is 850°C. More preferably, the temperature is 800°C. Here, the "center temperature" of the second heat treatment material is, for example, if it is a rectangular parallelepiped intermediate steel material with a thickness of about 500 mm equivalent to SKT4, the center temperature will rise to 600 to 950 if heated for 5 hours or more, preferably 7 hours or more. It tends to be ℃. In addition, in the present invention, when applying the second heat treatment step, it is preferable to carry out the second heat treatment step (continuously) following the heat treatment step (hair cracking prevention heat treatment). Furthermore, in order to apply the heat treatment process to a large steel ingot or slab, preheating may be performed before the second heat treatment process. Further, the cooling rate after the second heat treatment step may be determined by furnace cooling in which the treated material is held in the furnace and cooled more slowly than natural cooling.
本発明は必要に応じて第２熱処理工程後の鋼塊および中間鋼材に、３００～５５０℃で１２時間以上の熱処理を施す第３熱処理工程を実施することもできる。加熱温度の好ましい下限は４００℃であり、好ましい加熱温度の上限は５００℃である。
以上、説明する本発明の熱処理を行った鋼塊や鋼片は、その後に所定の形状に成形するための熱間鍛造等の熱間加工、所定の機械的性質を付与するための熱処理を行うことができる。
In the present invention, if necessary, the steel ingot and intermediate steel material after the second heat treatment step may be subjected to a third heat treatment step of heat treating at 300 to 550° C. for 12 hours or more. A preferable lower limit of the heating temperature is 400°C, and a preferable upper limit of the heating temperature is 500°C.
The steel ingots and billets that have been heat-treated according to the present invention described above are then subjected to hot processing such as hot forging to form them into a predetermined shape, and heat treatment to impart predetermined mechanical properties. be able to.
表１に示す成分を有する熱間金型用鋼（ＪＩＳ ＳＫＴ４相当鋼）の鋼塊を準備した。前記熱間金型用鋼の成分を表１に示す。なお本実施例で準備した鋼塊の水素含有量は１ｐｐｍ程度であった。 A steel ingot of hot mold steel (JIS SKT4 equivalent steel) having the components shown in Table 1 was prepared. Table 1 shows the ingredients of the hot die steel. Note that the hydrogen content of the steel ingot prepared in this example was about 1 ppm.
準備した鋼塊に対して、分塊鍛造および仕上げ鍛造を行って厚さが約４３０ｍｍ、重さ約１７ｔの中間鋼材とした。そして得られた中間鋼材に対して、表２に示すような熱処理工程を実施し、本発明例の熱間金型用鋼素材を得た。ここで分塊鍛造は約１２８０℃で行い、仕上げ鍛造は約１０００℃で行った。また第２熱処理工程後から第３熱処理工程の開始までは、炉冷を実施した。
前記熱間金型用鋼素材から毛割れの有無を確認するため、前記素材を幅方向に切断してサンプルを切り出し、断面を光学顕微鏡にて確認した。図１に観察写真を示す。図１に示すように、本発明例の試料からは、従来例である図２に存在する毛割れは確認されなかった。また、分塊鍛造、仕上げ鍛造を実施中や鍛造温度への加熱冷却中ともに、割れなどの問題もなく所定形状の熱間金型用鋼素材に加工ができた。
以上、説明するとおり、本発明によれば、鋼塊或いは熱間鍛造の段階で毛割れを防止可能なことが確認できた。
The prepared steel ingot was subjected to bloom forging and finish forging to obtain an intermediate steel material having a thickness of about 430 mm and a weight of about 17 tons. The obtained intermediate steel material was then subjected to a heat treatment process as shown in Table 2 to obtain a steel material for a hot mold according to an example of the present invention. Here, the blooming forging was performed at about 1280°C, and the finish forging was performed at about 1000°C. Furnace cooling was performed from after the second heat treatment step until the start of the third heat treatment step.
In order to confirm the presence or absence of hair cracking from the hot mold steel material, the material was cut in the width direction to cut out samples, and the cross section was confirmed using an optical microscope. Figure 1 shows an observation photograph. As shown in FIG. 1, the hair cracking present in the conventional example shown in FIG. 2 was not observed in the sample of the present invention. In addition, the steel material for hot molds could be processed into a predetermined shape without any problems such as cracking, both during blooming forging and finish forging, and during heating and cooling to the forging temperature.
As explained above, according to the present invention, it has been confirmed that hair cracking can be prevented at the stage of steel ingot or hot forging.
Claims (3)
前記鋼塊または該鋼塊を熱間加工した中間鋼材を熱処理する熱処理工程とを含み、
前記熱処理工程は３００～５５０℃で１２時間以上である熱間金型用鋼素材の製造方法。 a material preparation step of preparing a steel ingot of hot mold steel or an intermediate steel material obtained by hot working the steel ingot;
a heat treatment step of heat treating the steel ingot or an intermediate steel material obtained by hot working the steel ingot,
The method for producing a steel material for hot molds, wherein the heat treatment step is at 300 to 550°C for 12 hours or more.
The method for manufacturing a steel material for hot molds according to claim 1 or 2, wherein the steel ingot is a steel ingot after remelting.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2022093249A JP2023180123A (en) | 2022-06-08 | 2022-06-08 | Production method of steel material for hot die |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2022093249A JP2023180123A (en) | 2022-06-08 | 2022-06-08 | Production method of steel material for hot die |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2023180123A true JP2023180123A (en) | 2023-12-20 |
Family
ID=89235646
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2022093249A Pending JP2023180123A (en) | 2022-06-08 | 2022-06-08 | Production method of steel material for hot die |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2023180123A (en) |
-
2022
- 2022-06-08 JP JP2022093249A patent/JP2023180123A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111411285A (en) | Al and Ti microalloyed high-strength and high-toughness medium-entropy alloy and preparation method thereof | |
| US3219491A (en) | Thermal treatment of aluminum base alloy product | |
| KR101626820B1 (en) | magnesium-alloy plate and manufacturing method of it | |
| JPS6296603A (en) | Production of structural member made of heat-resistant high-strength al sintered alloy | |
| CN113877982A (en) | Hardly-deformable GH4720Li high-temperature alloy small-size bar, preparation method and blade forging | |
| CN113881909A (en) | Heat treatment method of GH4720Li high-temperature alloy blade forging and blade forging | |
| EP2700458A1 (en) | Titanium slab for hot rolling and process for producing same | |
| KR900006690B1 (en) | Method of producing thin sheet of high si-fe alloy | |
| CN115852119A (en) | H13 ingot casting forging hot-work die steel and production method thereof | |
| JP5155739B2 (en) | Steel bar manufacturing method | |
| JP5034583B2 (en) | Heat treatment method for duplex stainless steel pieces | |
| JP2023180123A (en) | Production method of steel material for hot die | |
| JP6324549B2 (en) | Titanium slab for surface melting treatment | |
| CN114029435B (en) | Technological method for eliminating 40CrNiMoA crankshaft steel strip structure | |
| CN114934162A (en) | Thermal deformation method of high-alloy martensitic stainless steel and stainless steel | |
| CN112708788B (en) | Method for improving plasticity of K403 alloy, die material and product | |
| KR101963428B1 (en) | Titanium alloy and fabrication method of titanium alloy | |
| CN114905010A (en) | Nickel-based alloy wire and preparation method thereof | |
| JPWO2017179652A1 (en) | Manufacturing method for titanium alloy and watch exterior parts | |
| JP2004269981A (en) | Production method of steel bar | |
| KR20160091863A (en) | Method for manufacturing of Al-Zn-Cu-Mg alloy sheet and Al-Zn-Cu-Mg alloy sheet thereby | |
| TWI557244B (en) | Method of fabricating corrosion-resistant high nickel alloy | |
| Hong et al. | Hot deformation behaviour and ledeburite refinement mechanism for hypoeutectoid low alloy white cast irons | |
| JP2708277B2 (en) | Method for producing hot rolled titanium alloy bar with excellent forgeability as rolled | |
| CN115896594B (en) | High-strength and high-toughness H13 die steel for aluminum extrusion and preparation method thereof |