JPS6335706B2 - - Google Patents
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- Publication number
- JPS6335706B2 JPS6335706B2 JP12473884A JP12473884A JPS6335706B2 JP S6335706 B2 JPS6335706 B2 JP S6335706B2 JP 12473884 A JP12473884 A JP 12473884A JP 12473884 A JP12473884 A JP 12473884A JP S6335706 B2 JPS6335706 B2 JP S6335706B2
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- weight
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- 229910045601 alloy Inorganic materials 0.000 claims description 61
- 239000000956 alloy Substances 0.000 claims description 61
- 239000011230 binding agent Substances 0.000 claims description 18
- 229910052751 metal Inorganic materials 0.000 claims description 17
- 239000002184 metal Substances 0.000 claims description 17
- 150000004767 nitrides Chemical class 0.000 claims description 15
- 150000002739 metals Chemical class 0.000 claims description 13
- 229910052750 molybdenum Inorganic materials 0.000 claims description 6
- 238000005245 sintering Methods 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- 239000012535 impurity Substances 0.000 claims description 3
- 239000000843 powder Substances 0.000 description 19
- 239000000203 mixture Substances 0.000 description 15
- 238000005242 forging Methods 0.000 description 14
- 239000002245 particle Substances 0.000 description 10
- 230000007423 decrease Effects 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 229910001339 C alloy Inorganic materials 0.000 description 5
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 5
- 229910052739 hydrogen Inorganic materials 0.000 description 5
- 239000001257 hydrogen Substances 0.000 description 5
- 230000035939 shock Effects 0.000 description 5
- 229910052721 tungsten Inorganic materials 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 230000002706 hydrostatic effect Effects 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 238000000465 moulding Methods 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 239000011812 mixed powder Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 102200082816 rs34868397 Human genes 0.000 description 2
- 241001391944 Commicarpus scandens Species 0.000 description 1
- -1 M 7 C 3 Chemical class 0.000 description 1
- 235000021355 Stearic acid Nutrition 0.000 description 1
- 229910009043 WC-Co Inorganic materials 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 238000000889 atomisation Methods 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000007580 dry-mixing Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000001513 hot isostatic pressing Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000000462 isostatic pressing Methods 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000011268 mixed slurry Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 description 1
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 238000004663 powder metallurgy Methods 0.000 description 1
- 102220062469 rs786203185 Human genes 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000008117 stearic acid Substances 0.000 description 1
Description
〔産業上の利用分野〕
この発明は、高温度で硬さが高く、熱間工具と
して使用されるCo−Cr−(W−Mo)−C系の耐熱
耐摩耗性を有する焼結合金に関するものである。
〔従来の技術及びその問題点〕
従来、Co−Cr−(W−Mo)−C系合金は、700
〜800℃附近までその高い硬さが低下せず、高温
での耐摩耗性にすぐれること、及び耐食性にすぐ
れることから、鋳造や肉盛で製造あるいは被覆さ
れ、種々の用途に広く用いられている。一方、こ
れらの合金を粉末冶金法によつて製造することも
一部実用化されている。
Co−Cr−(W−Mo)−C系合金の大きな用途に
熱間鍛造金型がある。熱間鍛造においては、鍛造
温度が金型材料の向上と共により高くなる傾向に
あるが、800℃以上の鍛造温度になると、Co−Cr
(W−Mo)−C系合金は軟化を起こし、金型とし
ての寿命が短かい。このような条件の熱間鍛造金
型にWC−Co系の超硬合金を用いることが試みら
れているが、焼バメして用いても熱衝撃によつて
クラツクを生じやすく、やはり寿命が短かく、現
在、800℃以上の熱間鍛造に用い得る焼結合金か
らなる適当な金型材料がないのが現状である。
〔発明の目的及び知見事項〕
本発明者らは、800℃以上の高温でもより長く
使用することができる熱間工具用材料について
種々試験・研究を重ねた結果、特定の組成を有す
るCo−Cr−(W−Mo)−C系合金に、特定の割合
で4a、5a及び6a族金属のうちの1種以上の金属
の窒化物あるいは炭窒化物を分散させることによ
り、800℃以上の高温での硬さ、ひいては耐摩耗
性を向上させることができ、また熱衝撃に対して
も超硬合金よりはるかに強い抵抗力を持たせるこ
とができ、したがつて、800℃以上の高温で熱間
鍛造金型等の熱間工具として用いたとき、殆んど
熱クラツクを生じさせないことを見い出した。
〔発明の構成に欠くことができない事項〕
この発明は上記知見事項に基いて発明されたも
のであり、分散相として、4a、5a及び6a族金属
のうちの1種以上の金属の窒化物若しくは炭窒化
物、又は、前記窒化物及び/又は炭窒化物の2種
以上:2〜20%、
結合相として、Co基合金:98〜80%からなる
組成(以上、重量%)を有し、しかも、
結合相としての前記Co基合金が
Cr:15〜35%、
Mo及びWのうちの1種又は2種:5〜25%、
C:1.0〜3.0%
を含有し、残りがCo及び不可避不純物からなる
組成(以上、重量%)を有するものであることを
特徴とする熱間工具用超耐熱耐摩焼結合金であ
る。
〔発明の構成要件〕
() 分散相
分散相は4a、5a及び6a族金属のうちの1種
以上の金属の窒化物若しくは炭窒化物、又は、
前記窒化物及び/又は炭窒化物の2種以上であ
つて、4a、5a及び6a族金属のうちの1種以上
の金属の窒化物若しくは炭窒化物とは、単一の
金属の窒化物あるいは炭窒化物と二種以上の金
属の複合窒化物(固溶体)あるいは複合炭窒化
物の両方を意味し、又、分散相が前記窒化物及
び/又は炭窒化物の2種以上とは異なつた窒化
物及び/又は炭窒化物が結合相中に混在状態に
あることを意味する。そして、その含有量は2
〜20重量%である。2重量%より少ないと、そ
の高温における硬さ、ひいては熱間工具として
用いたときの耐摩耗性の向上の効果、及び耐熱
衝撃性向上の効果が少なく、一方、20重量%を
越えて含有させると、分散粒子が多くて靭性及
び耐衝撃性において低下が著しくなり、熱間工
具として用いたとき、破損しやすくなるからで
ある。
又、得られた焼結合金の分散相を構成する
4a、5a及び6a族金属のうちの1種以上の金属
の窒化物あるいは炭窒化物の粒子の平均粒径は
3μm以下が好ましい。粒子が平均粒径3μmを
越えて粗くなると焼結合金の強度低下を起こ
す。したがつて、3μm以下が好ましいが0.5〜
2.0μmがもつとも好ましい。
() 結合相
結合相はCo−Cr−(W−Mo)−C系合金であ
つて、その含有量は98〜80重量%である。98重
量%を越えると、高温における硬さ、ひいては
熱間工具としての耐摩耗性の向上の効果及び耐
熱衝撃性向上の効果が少なく、一方、80重量%
未満では、靭性及び耐衝撃性において低下が著
しくなり、熱間工具として用いたとき、破損し
やすくなるからである。
以下、結合相としての前記の合金の組成を限
定する理由について述べる。
(a) Cr
Crは、この発明の合金において耐摩耗性
と耐食性、耐酸化性を向上させる重要な成分
であつて、この量が15重量%未満になると、
合金の高温硬さの低下が著しくなり、ひいて
は高温における耐摩耗性の低下をもたらし、
熱間工具として用いたときの寿命が短かく、
また耐食性、耐酸化性も低下する。一方、35
重量%を越えて含有すると靭性が低下し、熱
間工具として用いたとき、破損しやすくな
る。したがつて、Crの含有量を15〜35重量
%に定めた。
(b) Mo及びW
Mo及びWは、この合金系における炭化物
形成成分であつて、合金の高温における硬さ
と耐摩耗性の向上に著しい効果を有する。こ
の量が5重量%未満では、高温における硬さ
が低くなり耐摩耗性が低いし、一方、25重量
%を越えて含有させると、合金の靭性の低下
および耐酸化性の低下を起こすので、その含
有量を5〜25重量%に定めた。
(c) C
Cは、Cr、Mo及びWと炭化物(主とし
て、M7C3、M23C6、M6C)を形成して、こ
の合金の高温における硬さひいては耐摩耗性
を向上させる成分である。したがつて、Cの
最適量はCrの含有量とMo及びWの含有量に
関係し、Cr、Mo及びW量の多い組成では、
Cの最適量も高くなる。
C量が1.0重量%未満では、所定の高温に
おける硬さひいては耐摩耗性を維持すること
ができず、逆に、3.0重量%を越えて含有さ
せると硬くなりすぎて靭性の低下を伴うの
で、Cの含有量を1.0〜3.0重量%に定めた。
以上、結合相としてのCo基合金の組成の
限定理由を述べたが、焼結を促進するB、
P、Ca、Mg等の添加物やFe、Ni、Mn、Si
およびO等の不可避不純物を合計で、分散相
と結合相とからなる焼結合金を100重量%と
したとき、3重量%以下含有することも、こ
の発明の範囲である。
〔発明の附帯的事項〕
この発明に用いる結合相形成成分のCo基合金
の粉末の調製は溶湯のアトマイズによつて行なわ
れてもよいし、又は、Coの酸化物、Crの酸化物、
Moおよび/またはWの酸化物と炭素の粉末混合
物を還元雰囲気中で加熱することによつて還元す
る、共還元により行なわれてもよい。
又、分散相形成成分である4a、5a及び6a族金
属のうちの1種以上の金属の窒化物あるいは炭窒
化物の粉粒体は、市販のものを使用できるが、あ
らかじめ3μm以下に粉砕することによつて調製
するのが好ましい。
結合相形成成分と分散相形成成分の混合は、ボ
ールミル等を用いた湿式混合による方が、乾式混
合よりもすぐれた焼結体内の分散状態をもたらす
ので好ましい。
成形は、機械プレスあるいは静水圧プレスによ
り行なわれ、成形圧は、1〜5t/cm2の圧力が適当
である。
焼結は、真空度10-4〜10-1torrの真空中、また
は、ガス圧30〜760torrの還元雰囲気中で1250〜
1350℃の温度で0.5〜3時間加熱することにより
行なわれ、又、13〜20%の収縮を伴なつてほとん
ど空孔のない状態まで焼結可能である。また、空
孔の数を減少させて信頼性を高めるためには、更
に熱間静水圧焼結することが望ましい。
〔実施例〕
次に、実施例を比較例とともに述べることによ
り、この発明の構成と効果を詳細に述べる。以下
の実施例において、%は全て重量%を意味するも
のとする。
実施例 1
Coの酸化物粉末、Crの酸化物粉末、Wの酸化
物粉末および炭素粉末を、それぞれ41.4%、33.6
%、18.2%、6.8%の配合割合となるように配合
し、ガス圧760torrの水素中において1220℃で3
時間加熱することにより、水素と炭素による共還
元を行ない、45.3%Co−32%Cr−20%W−2.7%
Cの組成からなる平均粒径2.0μmの結合相形成成
分のCo基合金粉末を調製した。
平均粒径0.8μmの窒化チタン粉末が15%、前記
Co基合金粉末が85%の配合割合となるように配
合し、ボールミルにてアルコール中48時間の混合
を行ない、得られた混合スラリーを乾燥後、ガス
圧760torrの水素中において700℃で1時間加熱す
ることにより焼鈍した。この混合粉末に、混合粉
末の1.0%のステアリン酸を加え、3t/cm2の圧力
で静水圧プレスによる加圧成形を行ない、1300℃
において1時間真空(10-2torr)下で焼結を行な
つて、密度比99%の、配合組成と実質的に同じ組
成を有する焼結合金を得た。
本発明焼結合金は、ビツカース硬さで、
常温で 850Kg/mm2
700℃で 600Kg/mm2
800℃で 480Kg/mm2
を有するものであつた。
なお、比較として窒化チタン分散相のない結合
相形成成分のみの焼結合金のビツカーズ硬さを測
定したところ、
常温で 700Kg/mm2
700℃で 520Kg/mm2
800℃で 330Kg/mm2
であつた。
このように本発明焼結合金は高温においても、
なお高い硬さを有する。
次に、本発明焼結合金で作製された熱間鍛造金
型を用いてベベルギヤーを作る試験を行なつた。
被鍛造材はS35C、加熱温度は800℃であつた。従
来のダイス鋼製の金型の寿命は5000回であるのに
対し、本発明焼結合金製の金型の寿命は20000回
であつた。なお、分散相のない結合相形成成分の
みの焼結合金製の金型を用いた場合は、3000回で
あつた。
実施例 2
Arガスを用いたアトマイズ法によつて54.4%
Co−30%Cr−13%W−0.5%Fe−2.1%C組成の
平均粒径3.5μmの結合相形成成分としてのCo基
合金粉末を調製し、前記Co基合金粉末に平均粒
径1.0μmのTiC0.5N0.5粉末を、Co基合金85%、
TiC0.5N0.515%の配合割合となるように添加し、
超硬ボールを有する振動ミルを用いて72時間の湿
式混合を行なつた。この混合物を乾燥し、650℃
で1時間、ガス圧760torrの水素中で焼鈍した。
この粉末を3t/cm2の圧力で静水圧プレスによつて
成形し、1290℃においてガス圧760torrの水素中
1.5時間の焼結を行なつて、密度比97%の焼結合
金を得た。この焼結合金を1250℃、1000気圧の条
件で1時間熱間静水圧プレスを行ない、ほぼ密度
比100%の、配合組成と実質的に同じ組成を有す
る本発明焼結合金を得た。
本発明焼結合金はビツカース硬さで、
常温で 750Kg/mm2
700℃で 560Kg/mm2
800℃で 470Kg/mm2
であつた。
一方、TiC0.5N0.5を含まない結合相形成成分の
みの焼結合金のビツカース硬さは、
常温で 640Kg/mm2
700℃で 480Kg/mm2
800℃で 310Kg/mm2
であり、分散相による硬さの向上効果が明確にあ
らわれた。
次に、本発明焼結合金で作製された熱間鍛造金
型を用いてアームを作る試験を行なつた。被鍛造
材はS45C、加熱温度は830℃であつた。従来のダ
イス鋼製の金型の寿命は4000回であるのに対し、
本発明焼結合金製の金型の寿命は25000回であつ
た。なお、分散相のない結合相形成成分のみの焼
結合金製の金型を用いた場合は、3000回であつ
た。
実施例 3
Coの酸化物粉末、Crの酸化物粉末、Wの酸化
物粉末およびMoの酸化物粉末ならびに炭素粉末
を用いて共還元法よつて、第1表の各種の結合相
組成を有する結合相形成成分としてのCo基合金
粉末(平均粒径:2.0μm)を調製した。
次に、前記の各種Co基合金粉末に第1表記載
の各種の分散相組成を有する分散相形成成分を、
それぞれ第1表記載の含有率となるように添加
し、ボールミルにてアルコール中24時間混合し、
圧力3t/cm2で静水圧プレスによる加圧成形を行な
い、真空(真空度10-2torr)中で1300℃で1時間
焼結し、その後すべて1250℃、1000気圧の条件で
1時間熱間静水圧プレスを行ない、第1表記載の
焼結合金組成を有する本発明焼結合金No.1〜22及
び比較焼結合金No.1〜8を得た。
なお、従来焼結合金とは分散相を含まない結合
相のみの焼結合金のことであり、分散相形成成分
を添加しないことを除いては同様に製造されたも
のである。
これら本発明焼結合金、比較焼結合金及び従来
焼結合金について、800℃におけるビツカース硬
さ及び室温における抗折力を測定し、その結果を
第1表に示す。
又、本発明焼結合金製、比較焼結合金製及び従
来焼結合金製の熱間鍛造金型を用いて円板形状の
試験片を作る試験を行なつた。被鍛造材はS45C、
加熱温度は850℃であつた。このときの金型の寿
命を測定して、第1表に示した。この寿命は、金
型の摩耗量が大きくなり、バリを生ずるようにな
るまでに熱間鍛造することができる回数で表わ
す。
本発明焼結合金を用いたときは、いずれも金型
が破損することなく長寿命の熱間鍛造作業に耐え
たのに対し、比較焼結合金No.1、3、5及び7並
びに従来焼結合金では金型寿命が短かく、比較焼
結合金No.2、4、6及び8では靭性不足による金
型の割れを生じた。
[Industrial Application Field] This invention relates to a Co-Cr-(W-Mo)-C based sintered alloy that has high hardness at high temperatures and has heat and wear resistance and is used as a hot tool. It is. [Conventional technology and its problems] Conventionally, Co-Cr-(W-Mo)-C alloys have a 700
Its high hardness does not decrease up to around 800℃, and it has excellent wear resistance and corrosion resistance at high temperatures, so it is manufactured or coated by casting or overlaying, and is widely used in a variety of applications. ing. On the other hand, production of these alloys by powder metallurgy has also been partially put into practical use. Hot forging molds are a major use of Co-Cr-(W-Mo)-C alloys. In hot forging, the forging temperature tends to increase as the mold material improves, but when the forging temperature reaches 800℃ or higher, Co-Cr
(W-Mo)-C alloys soften and have a short life as molds. Attempts have been made to use WC-Co-based cemented carbide in hot forging dies under these conditions, but even when used in a shrink-fit manner, cracks tend to occur due to thermal shock, resulting in short life. Therefore, at present, there is no suitable mold material made of a sintered alloy that can be used for hot forging at temperatures of 800°C or higher. [Objectives and findings of the invention] The present inventors have conducted various tests and research on materials for hot tools that can be used for a longer period of time even at high temperatures of 800°C or higher. By dispersing nitrides or carbonitrides of one or more metals from group 4a, 5a, and 6a metals in a specific proportion in the -(W-Mo)-C alloy, it is possible to It can improve the hardness and wear resistance of the material, and it can also have much stronger resistance to thermal shock than cemented carbide, so it can be used at high temperatures of over 800℃ It has been found that when used as a hot tool such as a forging die, almost no thermal cracks occur. [Matters Essential to the Structure of the Invention] This invention was invented based on the above-mentioned findings, and includes a nitride or a metal nitride of one or more of group 4a, 5a, and 6a metals as a dispersed phase. Carbonitride, or two or more of the nitrides and/or carbonitrides: 2 to 20%, Co-based alloy as a binder phase: 98 to 80% (weight%), Moreover, the Co-based alloy as a binder phase contains Cr: 15 to 35%, one or both of Mo and W: 5 to 25%, C: 1.0 to 3.0%, and the remainder is Co and unavoidable. This is a super heat-resistant and wear-resistant sintered alloy for hot tools, characterized in that it has a composition (hereinafter, weight %) consisting of impurities. [Components of the invention] () Dispersed phase The dispersed phase is a nitride or carbonitride of one or more metals from group 4a, 5a and 6a metals, or
Two or more types of nitrides and/or carbonitrides, and nitrides or carbonitrides of one or more metals from group 4a, 5a, and 6a metals are nitrides or carbonitrides of a single metal. This refers to both a carbonitride and a composite nitride (solid solution) of two or more metals, or a composite carbonitride, and a nitride in which the dispersed phase is different from the two or more of the nitrides and/or carbonitrides. This means that carbonitrides and/or carbonitrides are mixed in the binder phase. And its content is 2
~20% by weight. If the content is less than 2% by weight, the effect of improving hardness at high temperatures, the wear resistance when used as a hot tool, and the effect of improving thermal shock resistance will be small; on the other hand, if the content exceeds 20% by weight This is because there are many dispersed particles, and the toughness and impact resistance are significantly reduced, making it easy to break when used as a hot tool. Also, it constitutes the dispersed phase of the obtained sintered alloy.
The average particle size of the particles of nitride or carbonitride of one or more metals of groups 4a, 5a and 6a is
The thickness is preferably 3 μm or less. When the particles become coarse and have an average particle diameter of more than 3 μm, the strength of the sintered alloy decreases. Therefore, it is preferably 3μm or less, but 0.5~
2.0 μm is also preferable. () Binding phase The binding phase is a Co-Cr-(W-Mo)-C alloy, and its content is 98 to 80% by weight. If it exceeds 98% by weight, the effect of improving hardness at high temperatures, the wear resistance as a hot tool, and the effect of improving thermal shock resistance will be small;
If it is less than that, the toughness and impact resistance will be significantly reduced, and when used as a hot tool, it will easily break. The reason for limiting the composition of the alloy as the binder phase will be described below. (a) Cr Cr is an important component that improves wear resistance, corrosion resistance, and oxidation resistance in the alloy of this invention, and when this amount is less than 15% by weight,
The high-temperature hardness of the alloy decreases significantly, resulting in a decrease in wear resistance at high temperatures.
It has a short lifespan when used as a hot tool,
Corrosion resistance and oxidation resistance also decrease. On the other hand, 35
If the content exceeds % by weight, the toughness will decrease and the tool will be easily damaged when used as a hot tool. Therefore, the Cr content was set at 15 to 35% by weight. (b) Mo and W Mo and W are carbide-forming components in this alloy system and have a remarkable effect on improving the hardness and wear resistance of the alloy at high temperatures. If this amount is less than 5% by weight, the hardness at high temperatures will be low and the wear resistance will be low, while if it is contained more than 25% by weight, the toughness and oxidation resistance of the alloy will decrease. Its content was set at 5 to 25% by weight. (c) C C forms carbides (mainly M 7 C 3 , M 23 C 6 , M 6 C) with Cr, Mo and W, and improves the hardness and wear resistance of this alloy at high temperatures. It is an ingredient. Therefore, the optimal amount of C is related to the content of Cr and the content of Mo and W, and in a composition with large amounts of Cr, Mo and W,
The optimum amount of C will also be higher. If the amount of C is less than 1.0% by weight, the hardness and wear resistance at a predetermined high temperature cannot be maintained, and conversely, if the content exceeds 3.0% by weight, it will become too hard and will be accompanied by a decrease in toughness. The content of C was set at 1.0 to 3.0% by weight. The reasons for limiting the composition of the Co-based alloy as a binder phase have been described above, but B, which promotes sintering,
Additives such as P, Ca, Mg, Fe, Ni, Mn, Si
It is also within the scope of the present invention to contain unavoidable impurities such as O and O in a total amount of 3% by weight or less when the sintered alloy consisting of the dispersed phase and the binder phase is 100% by weight. [Additional Matters to the Invention] The Co-based alloy powder used as the binder phase-forming component used in the present invention may be prepared by atomizing a molten metal, or may be prepared by atomizing a molten metal, or by using an oxide of Co, an oxide of Cr,
It may also be carried out by co-reduction, in which a powder mixture of Mo and/or W oxides and carbon is reduced by heating in a reducing atmosphere. In addition, commercially available powders of nitrides or carbonitrides of one or more metals of group 4a, 5a, and 6a metals, which are dispersed phase-forming components, can be used, but they must be ground to 3 μm or less in advance. Preferably, it is prepared by: It is preferable to mix the binder phase-forming component and the dispersed phase-forming component by wet mixing using a ball mill or the like, as this provides a better dispersion state in the sintered body than dry mixing. The molding is carried out using a mechanical press or a hydrostatic press, and a suitable molding pressure is 1 to 5 t/cm 2 . Sintering is performed in a vacuum with a vacuum degree of 10 -4 to 10 -1 torr or in a reducing atmosphere with a gas pressure of 30 to 760 torr at temperatures of 1250 to 1250 torr.
This is done by heating at a temperature of 1350° C. for 0.5 to 3 hours, and it can be sintered to a state with almost no pores, with a shrinkage of 13 to 20%. Furthermore, in order to reduce the number of pores and improve reliability, it is desirable to further perform hot isostatic pressure sintering. [Example] Next, the configuration and effects of the present invention will be described in detail by describing Examples and Comparative Examples. In the following examples, all percentages shall mean percentages by weight. Example 1 Co oxide powder, Cr oxide powder, W oxide powder and carbon powder were mixed at 41.4% and 33.6%, respectively.
%, 18.2%, and 6.8%, and heated at 1220℃ in hydrogen with a gas pressure of 760torr.
Co-reduction with hydrogen and carbon is performed by heating for a period of time, resulting in 45.3%Co-32%Cr-20%W-2.7%
A Co-based alloy powder having a composition of C and an average particle size of 2.0 μm as a binder phase forming component was prepared. 15% titanium nitride powder with an average particle size of 0.8 μm;
Co-based alloy powder was blended at a blending ratio of 85% and mixed in alcohol for 48 hours in a ball mill. After drying the resulting mixed slurry, it was placed in hydrogen at a gas pressure of 760 torr at 700℃ for 1 hour. Annealed by heating. To this mixed powder, 1.0% stearic acid was added to the mixed powder, and pressure molding was performed using a hydrostatic press at a pressure of 3t/cm 2 at 1300°C.
Sintering was carried out under vacuum (10 -2 torr) for 1 hour to obtain a sintered alloy having a density ratio of 99% and having substantially the same composition as the blended composition. The sintered alloy of the present invention had a Vickers hardness of 850 Kg/mm 2 at room temperature, 600 Kg/mm 2 at 700°C, and 480 Kg/ mm 2 at 800°C. For comparison, we measured the Vickers hardness of a sintered alloy with only binder phase forming components without a titanium nitride dispersed phase, and found that it was 700 Kg/mm 2 at room temperature, 520 Kg/mm 2 at 700°C, and 330 Kg/mm 2 at 800°C. Ta. In this way, the sintered alloy of the present invention can be used even at high temperatures.
Furthermore, it has high hardness. Next, a test was conducted to make a bevel gear using a hot forging die made of the sintered alloy of the present invention.
The material to be forged was S35C, and the heating temperature was 800℃. The life of the conventional mold made of die steel was 5000 times, whereas the life of the mold made of the sintered alloy of the present invention was 20000 times. In addition, when a mold made of a sintered alloy containing only binder phase forming components without a dispersed phase was used, the number of cycles was 3000. Example 2 54.4% by atomization method using Ar gas
A Co-based alloy powder as a binder phase forming component having a composition of Co-30%Cr-13%W-0.5%Fe-2.1%C and an average particle size of 3.5 μm was prepared, and the Co-based alloy powder had an average particle size of 1.0 μm. TiC 0.5 N 0.5 powder, Co-based alloy 85%,
TiC 0.5 N 0.5 Added at a blending ratio of 15%,
Wet mixing was performed for 72 hours using a vibratory mill with carbide balls. Dry this mixture at 650℃
It was annealed in hydrogen at a gas pressure of 760 torr for 1 hour.
This powder was molded using a hydrostatic press at a pressure of 3t/ cm2 , and then molded in hydrogen at a gas pressure of 760 torr at 1290°C.
After sintering for 1.5 hours, a sintered alloy with a density ratio of 97% was obtained. This sintered alloy was subjected to hot isostatic pressing at 1250°C and 1000 atm for 1 hour to obtain a sintered alloy of the present invention having a density ratio of approximately 100% and a composition substantially the same as the blended composition. The sintered alloy of the present invention had a Vickers hardness of 750 Kg/mm 2 at room temperature, 560 Kg/mm 2 at 700°C, and 470 Kg/ mm 2 at 800°C. On the other hand, the Vickers hardness of a sintered alloy containing only binder phase forming components without TiC 0.5 N 0.5 is 640 Kg/mm 2 at room temperature, 480 Kg/mm 2 at 700°C, and 310 Kg/mm 2 at 800°C. The effect of improving hardness was clearly seen. Next, a test was conducted to make an arm using a hot forging die made of the sintered alloy of the present invention. The material to be forged was S45C, and the heating temperature was 830℃. While the lifespan of conventional die steel molds is 4000 times,
The life of the mold made of the sintered alloy of the present invention was 25,000 times. In addition, when a mold made of a sintered alloy containing only binder phase forming components without a dispersed phase was used, the number of cycles was 3000. Example 3 Co-reduction method using Co oxide powder, Cr oxide powder, W oxide powder, Mo oxide powder, and carbon powder produced bonds having various binder phase compositions shown in Table 1. Co-based alloy powder (average particle size: 2.0 μm) as a phase-forming component was prepared. Next, dispersed phase forming components having various dispersed phase compositions listed in Table 1 were added to the various Co-based alloy powders described above.
Each was added to the content shown in Table 1, mixed in alcohol for 24 hours using a ball mill,
Pressure forming is performed using a hydrostatic press at a pressure of 3t/ cm2 , sintered at 1300℃ for 1 hour in a vacuum (degree of vacuum 10 -2 torr), and then hot-sintered for 1 hour at 1250℃ and 1000 atm. Isostatic pressing was performed to obtain sintered alloys Nos. 1 to 22 of the present invention and comparative sintered alloys Nos. 1 to 8 having the sintered alloy compositions shown in Table 1. The conventional sintered alloy refers to a sintered alloy containing only a binder phase and no dispersed phase, and was produced in the same manner except that no dispersed phase forming component was added. The Vickers hardness at 800° C. and the transverse rupture strength at room temperature were measured for the sintered alloy of the present invention, the comparative sintered alloy, and the conventional sintered alloy, and the results are shown in Table 1. Further, a test was conducted in which disk-shaped test pieces were made using hot forging dies made of the sintered alloy of the present invention, a comparative sintered alloy, and a conventional sintered alloy. The material to be forged is S45C,
The heating temperature was 850°C. The life of the mold at this time was measured and shown in Table 1. This life is expressed as the number of times hot forging can be performed before the amount of wear on the die becomes large and burrs occur. When the sintered alloys of the present invention were used, the molds withstood long-life hot forging work without breaking, whereas comparative sintered alloys Nos. 1, 3, 5, and 7 and the conventional sintered alloys The mold life of the alloys was short, and mold cracks occurred in comparative sintered alloys No. 2, 4, 6, and 8 due to lack of toughness.
【表】【table】
この発明の超耐熱耐摩焼結合金は、800℃以上
の高温において硬さを維持し、しかも、耐熱衝撃
性が優れており、抗折力も良好なので、熱間工具
として、特に、800℃以上の鍛造温度の熱間鍛造
金型として、今までの焼結合金では達成できなか
つたはるかに長寿命で、しかも従来のダイス鋼よ
りも長く使用することができる有用な材料であ
る。
The super heat-resistant and wear-resistant sintered alloy of this invention maintains its hardness at high temperatures of 800°C or higher, has excellent thermal shock resistance, and has good transverse rupture strength, so it can be used as a hot tool, especially at temperatures of 800°C or higher. It is a useful material that can be used as a hot forging mold at forging temperatures, and has a much longer life than conventional sintered alloys, and can be used for a longer period of time than conventional die steel.
Claims (1)
の1種以上の金属の窒化物若しくは炭窒化物、又
は、前記窒化物及び/又は炭窒化物の2種以上:
2〜20%、 結合相として、Co基合金:98〜80%からなる
組成(以上、重量%)を有し、しかも、 結合相としての前記Co基合金が Cr:15〜35%、 Mo及びWのうちの1種又は2種:5〜25%、 C:1.0〜3.0% を含有し、残りがCo及び不可避不純物からなる
組成(以上、重量%)を有するものであることを
特徴とする熱間工具用超耐熱耐摩焼結合金。[Scope of Claims] 1. A nitride or carbonitride of one or more metals from group 4a, 5a and 6a metals, or two or more of the nitrides and/or carbonitrides as a dispersed phase:
Cr: 15-20%, Co-based alloy as a binder phase: 98-80% (by weight), and the Co-based alloy as a binder phase contains Cr: 15-35%, Mo and It is characterized in that it contains one or two of W: 5 to 25%, C: 1.0 to 3.0%, and the remainder consists of Co and inevitable impurities (hereinafter referred to as weight %). Super heat-resistant and wear-resistant sintering alloy for hot tools.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP12473884A JPS613861A (en) | 1984-06-18 | 1984-06-18 | Sintered heat-and wear-resistant hard alloy for hot working tool |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP12473884A JPS613861A (en) | 1984-06-18 | 1984-06-18 | Sintered heat-and wear-resistant hard alloy for hot working tool |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS613861A JPS613861A (en) | 1986-01-09 |
JPS6335706B2 true JPS6335706B2 (en) | 1988-07-15 |
Family
ID=14892891
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP12473884A Granted JPS613861A (en) | 1984-06-18 | 1984-06-18 | Sintered heat-and wear-resistant hard alloy for hot working tool |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS613861A (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH06137526A (en) * | 1992-10-27 | 1994-05-17 | Nippon Steel Corp | Reduction heating burner as open fire for band steel |
JP6509290B2 (en) * | 2017-09-08 | 2019-05-08 | 三菱日立パワーシステムズ株式会社 | Cobalt-based alloy laminate shaped body, cobalt-based alloy product, and method for producing them |
CN109504868A (en) * | 2018-10-30 | 2019-03-22 | 湖南工业大学 | A kind of mine tool hard alloy and preparation method thereof |
-
1984
- 1984-06-18 JP JP12473884A patent/JPS613861A/en active Granted
Also Published As
Publication number | Publication date |
---|---|
JPS613861A (en) | 1986-01-09 |
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