TW202321480A - Hot work tool steel having excellent high-temperature strength and toughness - Google Patents
Hot work tool steel having excellent high-temperature strength and toughness Download PDFInfo
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- 229910001315 Tool steel Inorganic materials 0.000 title claims abstract description 34
- 150000001247 metal acetylides Chemical class 0.000 claims abstract description 56
- 238000010791 quenching Methods 0.000 claims abstract description 25
- 230000000171 quenching effect Effects 0.000 claims abstract description 24
- 239000012535 impurity Substances 0.000 claims abstract description 6
- 230000014759 maintenance of location Effects 0.000 claims abstract description 3
- 238000000034 method Methods 0.000 claims description 32
- 239000000203 mixture Substances 0.000 claims description 29
- 229910000717 Hot-working tool steel Inorganic materials 0.000 claims description 22
- 238000004458 analytical method Methods 0.000 claims description 18
- 229910052804 chromium Inorganic materials 0.000 claims description 18
- 229910052720 vanadium Inorganic materials 0.000 claims description 18
- 229910052750 molybdenum Inorganic materials 0.000 claims description 17
- 238000004453 electron probe microanalysis Methods 0.000 claims description 16
- 238000013507 mapping Methods 0.000 claims description 16
- 238000002441 X-ray diffraction Methods 0.000 claims description 12
- 238000010521 absorption reaction Methods 0.000 claims description 12
- 229910052799 carbon Inorganic materials 0.000 claims description 12
- 229910052748 manganese Inorganic materials 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 229910000831 Steel Inorganic materials 0.000 description 24
- 239000010959 steel Substances 0.000 description 24
- 230000000052 comparative effect Effects 0.000 description 14
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 11
- 230000000694 effects Effects 0.000 description 9
- 239000000463 material Substances 0.000 description 8
- 238000012360 testing method Methods 0.000 description 8
- -1 MC-based carbides Chemical class 0.000 description 7
- 238000011156 evaluation Methods 0.000 description 7
- 229910045601 alloy Inorganic materials 0.000 description 6
- 239000000956 alloy Substances 0.000 description 6
- 230000007423 decrease Effects 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- 238000005275 alloying Methods 0.000 description 5
- 238000005496 tempering Methods 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 238000005242 forging Methods 0.000 description 4
- 238000009863 impact test Methods 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 238000005204 segregation Methods 0.000 description 4
- 238000002791 soaking Methods 0.000 description 4
- 239000006104 solid solution Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 3
- 239000011159 matrix material Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 238000005498 polishing Methods 0.000 description 3
- 238000009497 press forging Methods 0.000 description 3
- 238000001192 hot extrusion Methods 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000004452 microanalysis Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000004512 die casting Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000014509 gene expression Effects 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000010191 image analysis Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- OXNIZHLAWKMVMX-UHFFFAOYSA-N picric acid Chemical compound OC1=C([N+]([O-])=O)C=C([N+]([O-])=O)C=C1[N+]([O-])=O OXNIZHLAWKMVMX-UHFFFAOYSA-N 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000011002 quantification Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 238000004846 x-ray emission Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/22—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for drills; for milling cutters; for machine cutting tools
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
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Abstract
Description
本發明係關於作為熱鍛造模具等之熱加工工具使用的高溫強度及韌性優良的熱加工工具鋼。The present invention relates to a hot working tool steel excellent in high temperature strength and toughness used as a hot working tool such as a hot forging die.
於熱壓鍛造、熱擠出或壓鑄用之熱加工工具(例如模具)，一般係使用日本產業規格(JIS)SKD61鋼，於熱鎚鍛造用之模具，係通用性地使用JIS SKT4鋼。JIS SKD61鋼，為強度及韌性雙方以比較高水準兼備之模具用鋼，但多有產生使用中之破裂所致之早期破損，於韌性方面不見得足夠。又，JIS SKD61鋼之韌性，在抑制熱疲勞龜裂之伸展的目的上為不足。JIS SKT4鋼，係重視韌性，使得亦可耐受鎚鍛造所造成的大的衝擊，另一方面由於軟化抵抗性低，故耐磨耗性不足。又，以再生加工為目的而重複進行模面的拉下時，淬火性低，故於中心部產生硬度降低，由於強度不足故破裂，而產生永久變形等。進而由於可應用之硬度低，故耐磨耗性及強度不足，不適於熱壓鍛造及熱擠出之用途。Hot working tools (such as dies) for hot press forging, hot extrusion or die casting generally use Japanese Industrial Standard (JIS) SKD61 steel, and JIS SKT4 steel is commonly used for hot hammer forging dies. JIS SKD61 steel is a mold steel with both strength and toughness at a relatively high level. However, early damage due to cracks during use often occurs, and the toughness may not be sufficient. Also, the toughness of JIS SKD61 steel is insufficient for the purpose of suppressing the expansion of thermal fatigue cracks. JIS SKT4 steel emphasizes toughness so that it can withstand a large impact caused by hammer forging. On the other hand, it has insufficient wear resistance because of its low softening resistance. In addition, when the mold surface is repeatedly pulled down for the purpose of recycling, the hardenability is low, so the hardness decreases at the center, and cracks and permanent deformation occur due to insufficient strength. Furthermore, due to the low applicable hardness, the wear resistance and strength are insufficient, and it is not suitable for hot press forging and hot extrusion.
專利文獻1中，提出一種熱加工工具鋼，其以質量%計，係由C：0.37~0.45%、Si：0.3~1.2%、Mn：0.6~1.5%、Ni：0.3~1.0%、Cr：1.0~2.0%、Mo：1.1~1.4%、V：0.1~0.3%，及剩餘部分Fe及不可避免雜質所構成，且合金成分之式L及式Y之值係規定於特定之範圍。再者，式L為-0.4×Si-9.7×Mn+3.7×Ni+54.4×Mo，式L之值為54~ 65。又，式Y為-17.1×C+0.1×Si+0.2×Mn+0.2×Ni+0.5×Cr+Mo+5.0，式Y之值為0.0以上。In Patent Document 1, a hot-working tool steel is proposed, which is composed of C: 0.37-0.45%, Si: 0.3-1.2%, Mn: 0.6-1.5%, Ni: 0.3-1.0%, Cr: 1.0~2.0%, Mo: 1.1~1.4%, V: 0.1~0.3%, and the rest Fe and unavoidable impurities, and the values of formula L and formula Y of the alloy composition are stipulated in a specific range. Furthermore, the formula L is -0.4×Si-9.7×Mn+3.7×Ni+54.4×Mo, and the value of the formula L is 54~65. Also, the formula Y is -17.1×C+0.1×Si+0.2×Mn+0.2×Ni+0.5×Cr+Mo+5.0, and the value of the formula Y is 0.0 or more.
但是，專利文獻1中，並未考慮到熱加工工具鋼作為熱加工工具而於高熱(高溫)使用之前(以下有稱為「高溫使用前」者)之碳化物析出狀態，高溫強度不充分。However, in Patent Document 1, the carbide precipitation state of the hot working tool steel before high heat (high temperature) use as a hot working tool (hereinafter referred to as "before high temperature use") is not considered, and the high temperature strength is insufficient.
又，專利文獻2中，提出一種熱加工用工具，其係以質量%計，為C：0.10~0.70%、Si：0.10~2.00%、Mn≦2.00%、Cr≦7.00%、W及Mo之單獨或複合之(1/2W+Mo)：0.20~12.00%、V≦3.00%、進而S：未達0.005%、O未達30ppm，且剩餘部分實質上由Fe所構成的組成。Also, in Patent Document 2, a tool for hot working is proposed, which is a combination of C: 0.10-0.70%, Si: 0.10-2.00%, Mn≦2.00%, Cr≦7.00%, W and Mo in terms of mass %. Alone or combined (1/2W+Mo): 0.20~12.00%, V≦3.00%, and S: less than 0.005%, O less than 30ppm, and the rest is substantially composed of Fe.
但是，專利文獻2中，均未考慮成分變動之幅度及高溫使用前之碳化物析出狀態，韌性為不充分。 [先前技術文獻] [專利文獻] However, in Patent Document 2, neither the range of component fluctuation nor the state of carbide precipitation before high-temperature use is considered, and the toughness is insufficient. [Prior Art Literature] [Patent Document]
[專利文獻1]日本特開2019-19374號公報 [專利文獻2]日本特開平11-106868號公報 [Patent Document 1] Japanese Patent Laid-Open No. 2019-19374 [Patent Document 2] Japanese Patent Application Laid-Open No. 11-106868
[發明所欲解決之課題][Problem to be Solved by the Invention]
熱加工工具鋼，由於高溫使用時碳化物(例如MC系碳化物、M 2C系碳化物等，M表示金屬元素)及碳氮化物會析出，而得到軟化抵抗亦即高溫強度。但是，於高溫使用前之階段若M 23C 6系碳化物為多，則高溫使用中之碳化物(例如MC系碳化物、M 2C系碳化物等)及碳氮化物之析出量減少，得不到高的高溫強度。又，高溫使用前若存在多量的巨大之碳化物，則係有韌性變低的問題。 Hot working tool steel, due to the precipitation of carbides (such as MC-based carbides, M 2 C-based carbides, etc., M represents metal elements) and carbonitrides when used at high temperatures, obtain softening resistance, that is, high-temperature strength. However, if there are many M 23 C 6 carbides before high-temperature use, the amount of carbides (such as MC-based carbides, M 2 C-based carbides, etc.) and carbonitrides in high-temperature use will decrease. High high temperature strength cannot be obtained. Also, if a large amount of huge carbides exist before high-temperature use, there is a problem of lower toughness.
因而，本發明所欲解決之課題，為藉由限定淬火條件，而將於壓鍛後可殘存之對高溫強度之貢獻小的M 23C 6系碳化物於淬火步驟中固溶，與此同時藉由控制成分變動之幅度，得到優良的韌性。此外，為藉由於淬火步驟中之M 23C 6系碳化物之固溶，增加基質中之碳量，作為熱加工工具鋼而於高溫使用中，使對高溫強度之貢獻大的微細之碳化物(例如MC系碳化物、M 2C系碳化物等)及微細之碳氮化物析出，藉以得到優良的高溫強度。亦即本發明所欲解決之課題，為提供具備韌性及高溫強度之熱加工工具鋼。 [用以解決課題之手段] Therefore, the problem to be solved by the present invention is to solid-solve the M 23 C 6 -based carbides that may remain after press forging and contribute little to the high-temperature strength in the quenching step by limiting the quenching conditions, and at the same time Excellent toughness can be obtained by controlling the range of component changes. In addition, in order to increase the amount of carbon in the matrix by the solid solution of M 23 C 6 carbides in the quenching step, as a hot-working tool steel used at high temperatures, fine carbides that contribute greatly to high-temperature strength (such as MC-based carbides, M 2 C-based carbides, etc.) and fine carbonitrides are precipitated to obtain excellent high-temperature strength. That is, the problem to be solved by the present invention is to provide hot-working tool steel with toughness and high-temperature strength. [Means to solve the problem]
為了克服上述課題，本發明者等人戮力進行開發的結果，發現藉由規定合金成分、淬火條件、碳化物狀態及成分變動之幅度，可得到兼備優良的高溫強度及韌性之熱加工工具鋼。In order to overcome the above-mentioned problems, as a result of intensive development by the present inventors, it was found that by specifying the alloy composition, quenching conditions, carbide state, and the range of composition variation, a hot-working tool steel with excellent high-temperature strength and toughness can be obtained. .
亦即為了解決上述課題，本發明提供以下之熱加工工具鋼。
[1] 一種熱加工工具鋼，其係以質量%計，由
C：0.20%以上且0.60%以下、
Si：0.10%以上且未達0.30%、
Mn：0.50%以上且2.00%以下、
Ni：0.50%以上且2.50%以下、
Cr：1.6%以上且2.6%以下、
Mo：0.3%以上且2.0%以下、
V：0.05%以上且0.80%以下，及
剩餘部分：Fe及不可避免的雜質
所構成的熱加工工具鋼，其中
熱加工工具鋼為經淬火回火之狀態，使得基於下式A：
值A=([T]+273)(log
10[t]+24)/1000 ･･･(A)
[式中，[T]表示淬火溫度(℃)，[t]表示淬火溫度保持時間(h)]
所算出之值A成為27.4以上且29.3以下，
使用前之熱加工工具鋼中，每10000μm
2之等效圓直徑1μm以上的碳化物之個數為150個以下。
[2] 如[1]之熱加工工具鋼，其中熱加工工具鋼滿足下式1~4：
依照本發明，提供自初期硬度之減少幅度為14HRC以內、夏比衝擊試驗亦為衝擊值70J/cm 2以上等兼備高溫強度及韌性之熱加工工具鋼。 According to the present invention, there is provided a hot-worked tool steel that has both high temperature strength and toughness, such that the decrease range of hardness from the initial stage is within 14HRC, and the Charpy impact test also has an impact value of 70J/cm 2 or more.
若規定成分變動之幅度而予以良好地控制時，則內部偏析小，夏比衝擊試驗之衝擊值成為85J/cm 2以上，因此可得到韌性更良好的熱加工工具鋼。 If the range of component fluctuation is specified and well controlled, the internal segregation will be small, and the impact value of the Charpy impact test will be more than 85J/ cm2 , so a hot-working tool steel with better toughness can be obtained.
本說明書中，將作為熱鍛造模具等之熱加工工具而於高熱(高溫)使用之前的熱加工工具鋼，稱為「使用前之熱加工工具鋼」。熱加工工具，例如係以提高加工性為目的，或以熱加工後用以得到所期望之特性的組織控制等為目的，而與被加熱至高溫的被加工材接觸，因此藉由自被加工材之熱移動，表面附近係被暴露於相當的溫度(例如180~1300℃)來使用。In this specification, the hot-working tool steel before being used as a hot-working tool such as a hot-forging die under high heat (high temperature) is referred to as "hot-working tool steel before use". Thermal processing tools, for example, are for the purpose of improving workability, or for the purpose of controlling the structure to obtain desired characteristics after thermal processing, and are in contact with the workpiece heated to a high temperature. The heat transfer of the material, the vicinity of the surface is exposed to a considerable temperature (eg 180~1300°C) for use.
以下，說明於本發明之熱加工工具鋼中，規定化學成分的理由、規定值A的理由，及規定碳化物之個數的理由。再者，化學成分中之%表示質量%。The reason for specifying the chemical composition, the reason for specifying the value A, and the reason for specifying the number of carbides in the hot-working tool steel of the present invention will be described below. In addition, % in a chemical composition shows mass %.
C：0.20%以上且0.60%以下 C為確保充分的淬火性，形成碳化物及碳氮化物藉以得到高溫強度、硬度及耐磨耗性之成分。C未達0.20%時，得不到充分的高溫強度。另一方面，C超過0.60%時，助長凝固偏析，產生巨大的碳化物及碳氮化物，韌性降低。又，因所產生之碳化物於淬火時未固溶地殘存，故作為熱加工工具鋼而高溫使用時之碳化物及碳氮化物的析出量減少，無法期望高溫強度之提高。因而，C為0.20%以上且0.60%以下。較佳為C為0.40%以上且0.60%以下。 C: 0.20% or more and 0.60% or less C is a component that ensures sufficient hardenability and forms carbides and carbonitrides to obtain high-temperature strength, hardness, and wear resistance. When C is less than 0.20%, sufficient high temperature strength cannot be obtained. On the other hand, when C exceeds 0.60%, solidification segregation is promoted, huge carbides and carbonitrides are generated, and toughness is lowered. In addition, since the generated carbides remain without solid solution during quenching, the amount of precipitation of carbides and carbonitrides when used at high temperatures as a hot-working tool steel is reduced, and improvement in high-temperature strength cannot be expected. Therefore, C is not less than 0.20% and not more than 0.60%. Preferably, C is 0.40% or more and 0.60% or less.
Si：0.10%以上且未達0.30% Si為於確保於製鋼之脫氧效果及淬火性所必要的成分。Si未達0.10%時，未發揮充分的效果。另一方面，Si為0.30%以上時，招致韌性降低。因而，Si為0.10%以上且未達0.30%。較佳為Si為0.10%以上且0.20%以下。 Si: more than 0.10% and less than 0.30% Si is an essential component for securing the deoxidizing effect and hardenability in steelmaking. When Si is less than 0.10%, sufficient effect is not exhibited. On the other hand, when Si is 0.30% or more, toughness falls. Therefore, Si is 0.10% or more and less than 0.30%. Si is preferably not less than 0.10% and not more than 0.20%.
Mn：0.50%以上且2.00%以下 Mn為於確保於製鋼之脫氧效果及淬火性所必要的成分。Mn未達0.50%時，未發揮充分的效果。Mn多於2.00%時，招致加工性之降低。因而，Mn為0.50%以上且2.00%以下。較佳為Mn為0.50%以上且1.40%以下。 Mn: 0.50% or more and 2.00% or less Mn is an essential component for securing the deoxidizing effect and hardenability in steelmaking. When Mn is less than 0.50%, sufficient effect is not exhibited. When Mn is more than 2.00%, workability will be reduced. Therefore, Mn is not less than 0.50% and not more than 2.00%. Preferably, Mn is 0.50% or more and 1.40% or less.
Ni：0.50%以上且2.50%以下 Ni係為了確保淬火性及提高韌性所必要之成分。Ni未達0.50%時，未發揮充分的效果。Ni多於2.50%時，成本變得過大。因而，Ni為0.50%以上且2.50%以下。較佳為Ni為1.10%以上且2.30%以下。 Ni: 0.50% to 2.50% Ni is an essential component for securing hardenability and improving toughness. When Ni is less than 0.50%, the sufficient effect is not exhibited. When Ni is more than 2.50%, the cost becomes excessive. Therefore, Ni is 0.50% or more and 2.50% or less. Preferably, Ni is 1.10% or more and 2.30% or less.
Cr：1.6%以上且2.6%以下 Cr係為了確保充分的淬火性所必要之成分。Cr未達1.6%時，得不到充分的淬火性。另一方面，以多於2.6%來添加Cr時，淬火回火時以Cr及Fe為主體之M 23C 6系之碳化物過多地形成，使高溫強度、軟化抵抗性及韌性降低。因而，Cr為1.6%以上且2.6%以下。較佳為Cr為1.6%以上且2.4%以下。 Cr: 1.6% or more and 2.6% or less Cr is a component necessary to ensure sufficient hardenability. When Cr is less than 1.6%, sufficient hardenability cannot be obtained. On the other hand, when more than 2.6% of Cr is added, M 23 C 6 carbides mainly composed of Cr and Fe are formed excessively during quenching and tempering, which reduces high temperature strength, softening resistance and toughness. Therefore, Cr is not less than 1.6% and not more than 2.6%. Preferably, Cr is 1.6% or more and 2.4% or less.
Mo：0.3%以上且2.0%以下 Mo係為了得到有助於淬火性、二次硬化及高溫強度之析出碳化物而有用的成分。Mo未達0.3%時，得不到充分的效果。Mo多於2.0%時，即使過剩地添加，效果亦達飽和，不僅如此，因碳化物進行巨大顆粒凝集，使韌性降低。又，成本變高。因而，Mo為0.3%以上且2.0%以下。較佳為Mo為0.3%以上且1.7%以下。 Mo: 0.3% to 2.0% Mo is a useful component for obtaining precipitated carbides that contribute to hardenability, secondary hardening, and high-temperature strength. When Mo is less than 0.3%, sufficient effects cannot be obtained. When Mo is more than 2.0%, the effect becomes saturated even if it is added excessively, and not only that, but also the toughness is lowered due to the carbides proceeding to agglomerate huge particles. Also, the cost becomes high. Therefore, Mo is 0.3% or more and 2.0% or less. Mo is preferably not less than 0.3% and not more than 1.7%.
V：0.05%以上且0.80%以下 V為回火時或作為熱加工工具鋼而於高溫使用中，使微細且硬質之碳化物及微細且硬質之碳氮化物析出，有助於強度及耐磨耗性之成分。V少於0.05%時，無法充分得到此等之效果。V多於0.80%時，凝固時巨大的碳化物及碳氮化物會結晶，而阻礙韌性。因而，V為0.05%以上且0.80%以下。較佳為V為0.05%以上且0.20%以下。 V: 0.05% or more and 0.80% or less V is a component that precipitates fine and hard carbides and fine and hard carbonitrides during tempering or when used as a hot-working tool steel at high temperatures, contributing to strength and wear resistance. When V is less than 0.05%, such effects cannot be sufficiently obtained. When V is more than 0.80%, huge carbides and carbonitrides will crystallize during solidification, which hinders toughness. Therefore, V is not less than 0.05% and not more than 0.80%. Preferably, V is not less than 0.05% and not more than 0.20%.
值A：27.4以上且29.3以下 使用前之熱加工工具鋼，為經淬火回火而使值A成為27.4以上且29.3以下之狀態。 Value A: 27.4 or more and 29.3 or less The hot-worked tool steel before use is quenched and tempered so that the value A becomes 27.4 or more and 29.3 or less.
值A係基於下式A算出。 值A=([T]+273)(log 10[t]+24)/1000 ･･･(A) 式A中，[T]表示淬火溫度(℃)，[t]表示淬火溫度保持時間(h)。 亦即，求得值A時，於式A中之[T]代入淬火溫度(℃)之數值，於式A中之[t]代入淬火溫度保持時間(h)之數值。 The value A was calculated based on the following formula A. Value A=([T]+273)(log 10 [t]+24)/1000 ･･･(A) In Formula A, [T] represents the quenching temperature (°C), and [t] represents the holding time of the quenching temperature ( h). That is, when obtaining value A, [T] in formula A is substituted into the value of quenching temperature (°C), and [t] in formula A is substituted into the value of quenching temperature holding time (h).
值A為藉由規定淬火溫度及保持時間，而用以確保碳化物之固溶性的指標。值A未達27.4時，本發明之成分中之鋼之淬火所致的碳化物之固溶變得不充分，因此作為熱加工工具而於高溫使用時之韌性及高溫強度不足。另一方面，值A超過29.3時，因舊沃斯田鐵結晶粒之巨大化，而韌性降低。因而，值A為27.4以上且29.3以下。The value A is an index for ensuring the solid solution of carbides by specifying the quenching temperature and holding time. When the value A is less than 27.4, the solid solution of carbides caused by quenching of the steel in the composition of the present invention becomes insufficient, so the toughness and high-temperature strength when used as a hot working tool at high temperature are insufficient. On the other hand, when the value A exceeds 29.3, the toughness is lowered due to the enlargement of the grains of old-Worth field iron. Therefore, the value A is not less than 27.4 and not more than 29.3.
每10000μm 2之等效圓直徑1μm以上的碳化物之個數：150個以下 於使用前之熱加工工具鋼中，等效圓直徑1μm以上的碳化物過多時，基質中之碳量不足，作為熱加工工具鋼而於高溫使用中所析出之碳化物(例如MC系碳化物、M 2C系碳化物等)及碳氮化物之量減少。藉由使碳化物(例如MC系碳化物、M 2C系碳化物等)及碳氮化物，作為熱加工工具鋼而於高溫使用中析出，而有助於高溫強度提高，因此若此等減少時，則得不到充分的高溫強度。又，等效圓直徑1μm以上的碳化物過多時，則應力集中，作為破裂之起點及傳播路徑而作用，因此會阻礙韌性。因而，於使用前之熱加工工具鋼中，每10000μm 2之等效圓直徑1μm以上的碳化物之個數係150個以下。 The number of carbides with an equivalent circle diameter of 1 μm or more per 10000 μm 2 : less than 150. In the hot-worked tool steel before use, if there are too many carbides with an equivalent circle diameter of 1 μm or more, the amount of carbon in the matrix is insufficient, as The amount of carbides (such as MC-based carbides, M 2 C-based carbides, etc.) and carbonitrides precipitated during high-temperature use in hot-working tool steels is reduced. Precipitating carbides (such as MC-based carbides, M 2 C-based carbides, etc.) and carbonitrides as hot-working tool steels during high-temperature use contributes to the improvement of high-temperature strength, so if these decrease When , sufficient high temperature strength cannot be obtained. Also, if there are too many carbides with an equivalent circle diameter of 1 μm or more, stress will concentrate and act as a starting point and propagation path of cracks, thereby hindering toughness. Therefore, in hot-worked tool steel before use, the number of carbides having a circle-equivalent diameter of 1 μm or more per 10,000 μm 2 is 150 or less.
每10,000μm 2之等效圓直徑1μm以上之大小的碳化物之個數，如實施例記載般，係使用淬火回火後之鋼材來測量。被測量之碳化物，例如為MC系碳化物、M 2C系碳化物、M 3C系碳化物、M 7C 3系碳化物、M 23C 6系碳化物等。再者，M表示金屬元素。 The number of carbides having a size of 1 μm or more per 10,000 μm 2 equivalent circle diameter is measured using quenched and tempered steel as described in the examples. The carbides to be measured are, for example, MC-based carbides, M 2 C-based carbides, M 3 C-based carbides, M 7 C 3 -based carbides, M 23 C 6 -based carbides, etc. In addition, M represents a metal element.
每10000μm 2之等效圓直徑1μm以上的碳化物之個數的測量，係遵照實施例記載之方法來進行。 The measurement of the number of carbides with a circle-equivalent diameter of 1 μm or more per 10000 μm 2 is carried out in accordance with the method described in the examples.
使用前之熱加工工具鋼，較佳滿足下式1~4：
式1~4中，[C] max及[C] min分別表示藉由電子探針微量分析法，以熱加工工具鋼之濃度測繪所決定的C之最高濃度(質量%)及最低濃度(質量%)，[Cr] max及[Cr] min分別表示藉由電子探針微量分析法，以熱加工工具鋼之濃度測繪所決定的Cr之最高濃度(質量%)及最低濃度(質量%)，[Mo] max及[Mo] min分別表示藉由電子探針微量分析法，以熱加工工具鋼之濃度測繪所決定的Mo之最高濃度(質量%)及最低濃度(質量%)，[V] max及[V] min分別表示藉由電子探針微量分析法，以熱加工工具鋼之濃度測繪所決定的V之最高濃度(質量%)及最低濃度(質量%)，[C]表示藉由紅外線吸收法，以熱加工工具鋼之組成分析所決定的C之含有率(質量%)，[Cr]、[Mo]及[V]分別表示藉由螢光X射線分析法，以熱加工工具鋼之組成分析所決定的Cr、Mo及V之含有率(質量%)。 In formulas 1 to 4, [C] max and [C] min respectively represent the maximum concentration (mass %) and minimum concentration (mass %) of C determined by the electron probe microanalysis method and the concentration mapping of hot-worked tool steel %), [Cr] max and [Cr] min respectively represent the maximum concentration (mass %) and minimum concentration (mass %) of Cr determined by the concentration mapping of hot-worked tool steel by electron probe microanalysis method, [Mo] max and [Mo] min respectively represent the maximum concentration (mass %) and minimum concentration (mass %) of Mo determined by the concentration mapping of hot-worked tool steel by electron probe microanalysis, [V] max and [V] min represent the highest concentration (mass %) and minimum concentration (mass %) of V determined by the concentration mapping of hot-worked tool steel by electron probe microanalysis method, and [C] represents the concentration obtained by Infrared absorption method, the C content (mass %) determined by the composition analysis of the hot-working tool steel, [Cr], [Mo] and [V] respectively represent the hot-working tool by the fluorescent X-ray analysis method Cr, Mo, and V contents (mass %) determined by steel composition analysis.
就合金元素X(X=C、Cr、Mo、V)而言，([X] max-[X] min)/[X]之值，為各合金元素之內部偏析所致之成分之偏差的指標。本說明書中，有將([X] max-[X] min)/[X]之值稱為「合金元素X之成分變動之幅度」者。若各合金元素之內部偏析所致之成分之偏差大(亦即([X] max-[X] min)/[X]之值大)時，碳化物及碳氮化物之分布差及變形能力差變大，因此會降低韌性。因而，較佳為規範C、Cr、Mo及V之成分變動之幅度。亦即，較佳為使用前之熱加工工具鋼滿足式1~4全部。 For alloying elements X (X=C, Cr, Mo, V), the value of ([X] max -[X] min )/[X] is the deviation of the composition caused by the internal segregation of each alloying element index. In this specification, the value of ([X] max -[X] min )/[X] is sometimes referred to as "the range of variation in the composition of the alloy element X". If the deviation of the composition caused by the internal segregation of each alloy element is large (that is, the value of ([X] max -[X] min )/[X] is large), the distribution of carbides and carbonitrides and deformability will be poor. The difference becomes large, thus reducing the toughness. Therefore, it is preferable to standardize the range of compositional variation of C, Cr, Mo, and V. That is, it is preferable that the hot-worked tool steel before use satisfies all of Expressions 1 to 4.
([X] max-[X] min)/[X]之值，如實施例所記載，係使用淬火回火後之鋼材而求得。將鋼材之L面(平行於鋼板之壓延方向及板厚方向之面，即所謂長度截面)進行鏡面研磨後，使用電子探針微量分析法(Electron Prove Micro Analysis：EPMA)，進行於0.5mm×0.5mm之範圍之合金元素X(X=C、Cr、Mo、V)的濃度測繪，將以該濃度測繪所決定的金屬元素X之最高濃度(質量%)及最低濃度(質量%)分別設為[X] max及[X] min。藉由紅外線吸收法進行鋼材之組成分析(C之含有率之分析)及藉由螢光X射線分析法進行鋼材之組成分析(Cr、Mo及V之含有率之分析)，將以紅外線吸收法所決定的C之含有率(質量%)設為[C]，將以螢光X射線分析法所決定的Cr、Mo及V之含有率(質量%)分別設為[Cr]、[Mo]及[V]。藉由電子探針微量分析法所進行的濃度測繪、藉由紅外線吸收法及螢光X射線分析法所進行的組成分析，係遵照實施例記載之方法進行。 The value of ([X] max -[X] min )/[X] was obtained by using quenched and tempered steel as described in the examples. After mirror-polishing the L surface of the steel material (the surface parallel to the rolling direction and thickness direction of the steel plate, the so-called length section), it is carried out at 0.5mm× Concentration surveying and mapping of alloying element X (X=C, Cr, Mo, V) in the range of 0.5mm, the highest concentration (mass %) and minimum concentration (mass %) of metal element X determined by the concentration surveying and mapping are respectively set For [X] max and [X] min . Composition analysis of steel by infrared absorption method (analysis of C content) and fluorescent X-ray analysis of steel composition (analysis of Cr, Mo and V content) will be carried out by infrared absorption method The determined C content (mass %) is [C], and the Cr, Mo, and V content (mass %) determined by the fluorescent X-ray analysis method are respectively [Cr] and [Mo] and [V]. Concentration mapping by electron probe microanalysis, and compositional analysis by infrared absorption and fluorescent X-ray analysis were carried out in accordance with the methods described in the examples.
於1225℃~1300℃之範圍，將鋼塊中心部均熱保持10~40小時之均熱(soaking)處理之應用，可有效果地減少成分變動之值。 [實施例] In the range of 1225 ℃ ~ 1300 ℃, the application of soaking (soaking) treatment of keeping the central part of the steel block for 10 ~ 40 hours can effectively reduce the value of the composition change. [Example]
以下，基於實施例及比較例，以更詳細說明本發明。 發明例No.1~28及比較例No.29~40，分別為由表1記載之化學成分與剩餘部分Fe及不可避免雜質所構成之鋼。將各鋼100kg以真空感應熔解爐(VIM)熔製，造塊為鑄塊。關於發明鋼No.1~20，係以上述條件進行均熱處理(亦即於1225℃~1300℃之範圍，將鋼塊中心部均熱保持10~40小時之均熱處理)。之後，將此等鑄塊加熱至1220℃，鍛伸(cogging)為15mm見方(15mm×15mm)之方形材。塊材(bulk)之各鋼之成分組成，係以紅外線吸收法(C之含有率之分析)及螢光X射線分析法(C以外之合金元素之含有率之分析)確認。紅外線吸收法及螢光X射線分析法係如後述般進行。 Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples. Inventive Examples No.1~28 and Comparative Examples No.29~40 are steels composed of the chemical composition listed in Table 1, the remainder Fe and unavoidable impurities. 100 kg of each steel was melted in a vacuum induction melting furnace (VIM), and the blocks were made into ingots. Regarding invention steel Nos. 1~20, the soaking treatment was carried out under the above conditions (that is, the soaking treatment in which the central part of the steel block was soaked for 10~40 hours in the range of 1225°C~1300°C). Afterwards, these ingots were heated to 1220° C., and cogged into square bars of 15 mm square (15 mm×15 mm). The composition of each steel in bulk is confirmed by infrared absorption method (analysis of C content) and fluorescent X-ray analysis (analysis of content of alloy elements other than C). The infrared absorption method and the fluorescent X-ray analysis method were performed as mentioned later.
之後，加熱至850~960℃，藉由保持各種時間(30分鐘~3小時)，得到沃斯田鐵組織。接著實施油冷之淬火，進一步加熱至500~700℃後，實施2次氣冷之回火，調質為39~41HRC。進一步以機械加工而得到供試材。 再者，表1中，各鋼之剩餘部分，為Fe及不可避免的雜質。 Afterwards, heat to 850~960°C and hold for various times (30 minutes~3 hours) to obtain the iron structure of Worth field. Then implement oil-cooled quenching, further heat to 500~700°C, and implement 2 times of air-cooled tempering, quenching and tempering to 39~41HRC. The test material was obtained by further machining. In addition, in Table 1, the remainder of each steel is Fe and unavoidable impurities.
(值A之算出) 基於下式A： 值A=([T]+273)(log 10[t]+24)/1000 ･･･(A) [式中，[T]表示淬火溫度(℃)，[t]表示淬火溫度保持時間(h)]， 算出各鋼之值A。各鋼之淬火溫度(℃)、保持時間(h)及值A係如表2所示。 (Calculation of value A) Based on the following formula A: Value A=([T]+273)(log 10 [t]+24)/1000 ･･･(A) [where [T] represents the quenching temperature (°C ), [t] represents the quenching temperature holding time (h)], calculate the value A of each steel. The quenching temperature (°C), holding time (h) and value A of each steel are shown in Table 2.
(碳化物量之測定) 將各供試材之中心以拋光研磨而進行鏡面研磨後，以苦味酸醇溶液使基質腐蝕，選擇30個視野之觀察到多數之可見淡灰色或白色之碳化物的部位，以電子顯微鏡，藉由影像解析測量以10,000倍所觀察的等效圓直徑1μm以上的碳化物個數。以每10,000μm 2之等效圓直徑1μm以上的碳化物個數為150個以下者為「A」，以較其個數多者為「C」。碳化物量之測定結果如表2所示。 (Measurement of the amount of carbides) After mirror-polishing the center of each test material by polishing and grinding, the matrix was corroded with picric acid alcohol solution, and most of the visible light gray or white carbides were observed in 30 fields of view. , with an electron microscope, the number of carbides with an equivalent circle diameter of 1 μm or more observed at 10,000 times is measured by image analysis. The number of carbides with a diameter of 1 μm or more per 10,000 μm 2 equivalent circle is 150 or less as "A", and the one with a larger number is "C". The measurement results of the amount of carbides are shown in Table 2.
(成分變動之幅度之評價) 針對各供試材，將其L面(平行於鋼板之壓延方向及板厚方向之面，即所謂長度截面)予以鏡面研磨後，使用電子探針微量分析法(Electron Prove Micro Analysis：EPMA)，進行於0.5mm×0.5mm之範圍之合金元素X(X=C、Cr、Mo、V)的濃度測繪。 (Evaluation of the range of composition changes) For each test material, the L surface (the surface parallel to the rolling direction and thickness direction of the steel plate, that is, the so-called length section) is mirror-polished, and then the electron probe microanalysis method (Electron Prove Micro Analysis: EPMA) is used. Concentration mapping of alloying elements X (X=C, Cr, Mo, V) in the range of 0.5mm×0.5mm.
EPMA係由以下條件進行。 分析裝置：島津製作所股份有限公司製EPMA1600 加速電壓：15kV 光束直徑：2μm 照射電流：0.1μA 掃描模式：試驗台掃描(stage scan) 步寬(step size)(1次之測定面積)：2.5μm×2.5μm 步數(step number)(測定部位數)：200×200 測定時間(1步)：50ms 分光結晶：C LS12L Mo PET Cr、V LIF EPMA was performed under the following conditions. Analyzer: EPMA1600 manufactured by Shimadzu Corporation Acceleration voltage: 15kV Beam diameter: 2μm Irradiation current: 0.1μA Scan mode: stage scan Step size (1 measurement area): 2.5μm×2.5μm Step number (number of measurement sites): 200×200 Measurement time (1 step): 50ms Spectroscopic crystal: C LS12L Mo PET Cr, V LIF
針對各供試材，藉由紅外線吸收法進行組成分析(C之含有率之分析)及藉由螢光X射線分析法進行組成分析(Cr、Mo及V之含有率之分析)。Composition analysis (analysis of C content) by infrared absorption method and composition analysis (analysis of Cr, Mo and V content) by fluorescent X-ray analysis were performed on each test material.
藉由紅外線吸收法所進行的組成分析，係使用堀場製作所製碳硫分析裝置EMIA-Expert，基於JIS Z 2615：2015 「金屬材料之碳定量法通則」之「紅外線吸收法」來進行。Composition analysis by infrared absorption method is carried out based on the "infrared absorption method" of JIS Z 2615:2015 "General Principles of Carbon Quantification Method for Metallic Materials" using the carbon and sulfur analyzer EMIA-Expert manufactured by Horiba Seisakusho.
藉由螢光X射線分析法(XRF)所進行之組成分析，使用島津製作所製MXF-2400，基於JIS G 1256：2013 「鐵及鋼-螢光X射線分析方法」來進行。Composition analysis by fluorescent X-ray analysis method (XRF) was performed based on JIS G 1256:2013 "Iron and Steel-Fluorescent X-ray Analysis Method" using MXF-2400 manufactured by Shimadzu Corporation.
將以濃度測繪所決定的合金元素X之最高濃度(質量%)及最低濃度(質量%)分別設為[X] max及[X] min，將以紅外線吸收法所決定的C之含有率(質量%)設為[C]，將以螢光X射線分析法所決定的Cr、Mo及V之含有率(質量%)分別設為[Cr]、[Mo]及[V]，算出([X] max-[X] min)/[X]之值作為成分變動之幅度。成分變動之幅度之評價結果係如表3A~表3D所示。 Set the maximum concentration (mass %) and minimum concentration (mass %) of the alloying element X determined by concentration mapping as [X] max and [X] min respectively, and the content of C determined by the infrared absorption method ( Mass %) is set to [C], and the contents (mass %) of Cr, Mo, and V determined by the fluorescent X-ray analysis method are set to [Cr], [Mo], and [V], respectively, to calculate ([ X] max -[X] min )/[X] as the range of component changes. The evaluation results of the range of component changes are shown in Table 3A~Table 3D.
於C、Cr、Mo及V之全部合金元素中，([X] max-[X] min)/[X]之值滿足規定要件時，作為滿足成分變動之幅度的規定要件之優良者而評價為「A」，只要有一成分變動幅度大，未滿足規定要件者係作為不良者而評價為「C」。成分變動之幅度之評價結果係如表2所示。 Among all the alloy elements of C, Cr, Mo and V, when the value of ([X] max -[X] min )/[X] satisfies the specified requirements, it is evaluated as an excellent one that satisfies the specified requirements for the range of compositional fluctuations As "A", as long as there is a large variation in one component, those that do not meet the specified requirements are regarded as defective and evaluated as "C". Table 2 shows the evaluation results of the range of component changes.
C、Cr、Mo及V之規定要件係如以下所述。
(高溫強度之評價) 測定各供試材之HRC硬度後，進一步於600℃保持100小時後，進行氣冷，測定於室溫之HRC硬度，以距初期硬度之減少值而評價高溫強度。以減少值為14HRC以下者為「A」，減少值大於此者為「C」。高溫強度之評價結果係如表2所示。 (evaluation of high temperature strength) After measuring the HRC hardness of each test material, it was further kept at 600°C for 100 hours, then air-cooled, and the HRC hardness at room temperature was measured, and the high-temperature strength was evaluated by the decrease value from the initial hardness. The one whose reduction value is below 14HRC is "A", and the one whose reduction value is greater than this is "C". The evaluation results of high temperature strength are shown in Table 2.
(韌性之評價) 由各供試材，形成JIS規定(JIS Z2242)之3號由寬10mm、長55mm所成之U切口之試驗片，對試驗片實施淬火回火，使硬度成為39~41HRC，藉由於常溫進行夏比衝擊試驗來評價韌性。衝擊值70J/cm 2以上者為「A」、特別是85J/cm 2以上為「A +」，未達70J/cm 2者為「C」。韌性之評價結果如表2所示。 (Evaluation of Toughness) From each test material, form a test piece with a U-cut of No. 3 in JIS (JIS Z2242) with a width of 10mm and a length of 55mm, and quench and temper the test piece to make the hardness 39~41HRC , to evaluate toughness by performing Charpy impact test at room temperature. If the impact value is 70J/ cm2 or more, it is "A", especially if it is 85J/cm2 or more , it is "A + ", and if it is less than 70J/ cm2 , it is "C". The evaluation results of toughness are shown in Table 2.
發明例No.1~28，係如表1及表2所示，均為在化學成分之規定範圍內，滿足式A之值，且等效圓直徑1μm以上的碳化物個數亦少者。因此，夏比衝擊試驗中之衝擊值顯示出70J/cm 2以上，韌性為A評價，自初期硬度之減少幅度亦為14HRC以內，高溫強度(軟化抵抗性)亦為A評價，可得到兼備優良的高溫強度及韌性之熱加工工具鋼。 Invention examples No.1~28, as shown in Table 1 and Table 2, are all within the specified range of chemical composition, satisfy the value of formula A, and the number of carbides with an equivalent circle diameter of 1 μm or more is also small. Therefore, the impact value in the Charpy impact test shows more than 70J/cm2, the toughness is evaluated as A, the decrease in hardness from the initial stage is also within 14HRC, and the high temperature strength (softening resistance) is also evaluated as A, which can be obtained with both excellent Hot working tool steel with excellent high temperature strength and toughness.
比較例No.29由於C量少，故為高溫強度低者。 比較例No.30由於C量多，等效圓直徑1μm以上的碳化物個數多，成分變動之幅度大，故為韌性及高溫強度低者。 比較例No.31為Si量多，韌性低者。 比較例No.32為Ni量少，韌性低者。 比較例No.33由於Cr量多，等效圓直徑1μm以上的碳化物個數多，成分變動之幅度大，故為韌性及高溫強度低者。 比較例No.34為Mo量少，高溫強度低者。 比較例No.35由於Mo量多，等效圓直徑1μm以上的碳化物個數多，成分變動之幅度大，故為韌性及高溫強度低者。 比較例No.36為V量少，高溫強度低者。 比較例No.37由於V量多，等效圓直徑1μm以上的碳化物個數多，成分變動之幅度大，故為韌性低者。 比較例No.38由於式A之值小，等效圓直徑1μm以上的碳化物個數多，故為韌性及高溫強度低者。 比較例No.39為式A之值大，韌性低者。 比較例No.40為等效圓直徑1μm以上的碳化物個數多，韌性及高溫強度低者。 Comparative Example No. 29 has low high-temperature strength due to the small amount of C. Comparative Example No.30 has a large amount of C, a large number of carbides with an equivalent circle diameter of 1 μm or more, and a large variation in composition, so it has low toughness and high temperature strength. Comparative Example No. 31 has a large amount of Si and low toughness. Comparative Example No. 32 has a small amount of Ni and low toughness. Comparative Example No. 33 has a large amount of Cr, a large number of carbides with an equivalent circle diameter of 1 μm or more, and a large variation in composition, so it has low toughness and high temperature strength. Comparative Example No. 34 is one with a small amount of Mo and low high-temperature strength. Comparative Example No. 35 has a large amount of Mo, a large number of carbides with an equivalent circle diameter of 1 μm or more, and a large variation in composition, so it has low toughness and high temperature strength. Comparative Example No. 36 has a small amount of V and low high-temperature strength. Comparative Example No. 37 has a large amount of V, a large number of carbides with an equivalent circle diameter of 1 μm or more, and a large variation in composition, so it has low toughness. Comparative Example No. 38 has low toughness and high temperature strength due to the small value of formula A and the large number of carbides with an equivalent circle diameter of 1 μm or more. Comparative Example No. 39 has a large value of formula A and low toughness. Comparative Example No. 40 has a large number of carbides with an equivalent circle diameter of 1 μm or more, and low toughness and high temperature strength.
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