JPS60110840A - Sintered hard alloy for hot plastic working and its production - Google Patents

Abstract

PURPOSE:To produce a sintered hard alloy for hot plastic working having excellent resistance to thermal cracking, etc. by cooling quickly a sintered hard alloy consisting of a hard phase composed of a specific ratio of WC and a bond phase composed of Co, Ni, Cr by a gaseous substance from the sintering temp. in the course of sintering said alloy. CONSTITUTION:A sintered hard alloy having the hard phase composed of WC and the bond phase composed of Co, Ni, Cr in which 99>=Co/Ni>=1 and 0.1- 3wt% Cr and the amt. thereof is 10-40% is quickly cooled by a gaseous substance such as He, H2 or the like having high heat conductivity from the sintering temp. to make the soldified and sintered particles of the bond phase about <=0.3mm., more preferably about <=0.1mm.. The resultant sintered hard alloy has high high-temp. strength, high-temp. toughness and wear resistance and excellent resistance to thermal cracking and fracture and exhibits high performance and a long life when used as a tool for hot forging.

Description

【発明の詳細な説明】 高寿命の超硬合金を提供するものである。[Detailed description of the invention] This provides a long-life cemented carbide.

（ロ）従来技術とその問題点 従来熱間鍛造用工具である金型、パンチはダイス鋼（Ｓ
ＫＤ６１）が主に使われていた。ダイスｔｉ］ｉｌは表
面に熱亀裂変形が発生しやすいため、スを而は短かく、
製品の・Ｊ法４１゛ｊ度が悪いのが現状である。(b) Conventional technology and its problems Conventional hot forging tools, such as dies and punches, are made of die steel (S
KD61) was mainly used. Since thermal crack deformation easily occurs on the surface of the die, the length of the die should be short.
Currently, the quality of the product is poor.

従°つて熱間鍛造後の１１１５品ｅよ、Ｊｉ７Ｆ削加工
が必要とされている。最近の動向として、温間鍛造、熱
開鍛這による精密鍛ｊＬＬを行い、後加工を省略する方
向の開発が進められている。これには高１１能鍛造用工
具が必要とされる。従来から用、いられている熱間ダイ
ス鋼では肌荒れ、変形、熱亀裂が著しくま１、：佑の熱
膨張が大きいためｌ’ｌｒｊ精反を出すことは出来ない
。高温での硬度が高い５ＫＨ−５１でも熱膨張、熱亀裂
、クランクの問題があり高寿命を望めない。高温での熱
膨張が鋼の１／２である超硬合金は望ましいが、現在市
場で用いられている超硬合金は１ｌｌｌＪ熱衝撃性、靭
性が低いため熱間鍛造の如く、厳しい使用条件下では使
用に耐えない。Accordingly, 1115 items e after hot forging require Ji7F machining. As a recent trend, development is proceeding in the direction of omitting post-processing by performing precision forging using warm forging and hot open forging. This requires high-performance forging tools. The hot die steel that has been used in the past suffers from severe roughening, deformation, and thermal cracking, and cannot produce high-strength steel because of its large thermal expansion. Even 5KH-51, which has high hardness at high temperatures, has problems with thermal expansion, thermal cracking, and cranking, so a long life cannot be expected. Cemented carbide, whose thermal expansion at high temperatures is half that of steel, is desirable, but the cemented carbide currently used in the market has low thermal shock resistance and toughness, so it cannot be used under harsh conditions such as hot forging. It cannot withstand use.

（９発明の開示 本発明は温間、熱間鍛造用工具として、蔑温硬板が高く
、熱膨張率の低い超硬合金の改良を進めた結果、側熱亀
裂性、１６ｉｔ割損性の曖れた熱間塑性加工用Ｉ置棚合
金を開発できたものである。(Disclosure of 9 Inventions The present invention is a tool for warm and hot forging, as a result of improving a cemented carbide with a high cold hard plate and a low coefficient of thermal expansion. We were able to develop a vague I-shelf alloy for hot plastic working.

本願の要旨は、硬質層と結合４１１よりなる超硬合金に
あ・いて、硬質相がＷＣよりなり、結合相がＣｏ。The gist of the present application is a cemented carbide made of a hard layer and a bond 411, in which the hard phase is made of WC and the bonding phase is Co.

Ｎｉ、Ｃｒの三元合金からなり、該結合相量がｌＯ〜４
０車：１１−％にあり、かつＣＯとＮｉの比較が９９≧
Ｃｏ／Ｎ　ｉ　、−：　Ｉであり、Ｃｒの添〃１１量が
０．１〜３Ｑｉ％である超硬合金を急冷処理により結合
相の凝固粒度を３００７ｚ以下に１ｌｉｌｌ　御したこ
とを特徴とする合金が、温熱間鍛造用超硬合金工具に適
していることを見出したものである。It is made of a ternary alloy of Ni and Cr, and the amount of the binder phase is lO~4
0 car: 11-% and comparison of CO and Ni is 99≧
Co/N i , -: I, and the solidified grain size of the binder phase is controlled to 3007z or less by quenching a cemented carbide in which the amount of Cr added is 0.1 to 3Qi%. It has been discovered that the alloy is suitable for use in cemented carbide tools for hot and hot forging.

ｉ’ｌｌ１口１１」、熱間鍛造では被加工物の温度がｉ
’ｎｉ　＜、また鍛造材料の変形による発熱にて金型表
面の温度が急上昇する。一方ワーク取り出し後潤滑剤、
冷却水、冷却油等を金型表面に吹きつけるため急冷され
るなどの熱衝撃により工具表面の損傷が起こる。なおこ
こでいう温−間とは約５００〜８００℃であり、熱間と
は約８００〜１１００℃の範囲を示すものである。i'll 1 mouth 11'', in hot forging the temperature of the workpiece is i
'ni <, and the temperature of the mold surface rises rapidly due to heat generation due to the deformation of the forging material. On the other hand, after taking out the work, lubricant
Damage to the tool surface occurs due to thermal shock caused by rapid cooling as cooling water, cooling oil, etc. are sprayed onto the mold surface. Note that the term "warm" here refers to a temperature of about 500 to 800°C, and the term "hot" refers to a range of about 800 to 1100°C.

本発明では、急激な熱サイクル、工具表面温度の上昇に
よる高温硬板の低下、鍛造時に必要な高温靭性、冷却水
による］工具表面の腐食、被加工物子による磨耗等の悪
条件下でも使用可能な超硬合金を見出したものである。The present invention can be used even under adverse conditions such as sudden thermal cycles, deterioration of high-temperature hard plate due to increase in tool surface temperature, high-temperature toughness required during forging, corrosion of tool surface due to cooling water, and wear due to workpiece objects. We have discovered a possible cemented carbide.

例えば熱間で使用１される超硬合金として銅線拐圧延に
ノ１［いられる圧延ロールが知られているが、これは圧
延時は、均等荷重下で用いられ、本−の熱間鍛造工具の
ような強い衝撃は加わっていないことからも、本願でい
う使用条件がいかに厳しいかが推定できるわけである。For example, as a cemented carbide used in hot rolling, there is a known rolling roll that can be used for copper wire rolling. The fact that no strong impact like a tool was applied to it can be inferred how severe the conditions of use are in this application.

本発明者らは、硬質相としてＷＣを用い結合相としてＣ
ｏを用いた場合、第１図に示す通り高温での硬板低下が
著しいこと、また第２図に示すように高温靭性値が低下
するとの新らしい知見に基くものである。即ち、ＷＣ−
ＣＯ系１石硬合金にＮｉ　−Ｃｒが加わると靭性が低下
するとされているが、９９≧Ｃｏ７’Ｎｉ七ｌの条件で
は合金の靭性を低下させることなく高強度を維持できる
ことができる。Ｃｒの添加は冷却水による超硬合金工具
表面の肌荒れを減少することができ０．１％以下では効
果がなく、また３重１ｉ１０％を越えると強度が低下す
るため、０．１〜３重量％の範囲が望ましい。The present inventors used WC as the hard phase and C as the binder phase.
This is based on the new finding that when o is used, the hardness of the hard plate at high temperatures decreases significantly as shown in FIG. 1, and the high temperature toughness value decreases as shown in FIG. That is, WC-
It is said that the addition of Ni - Cr to a CO-based single-stone hard alloy reduces its toughness, but under the condition of 99≧Co7'Ni7l, high strength can be maintained without reducing the toughness of the alloy. The addition of Cr can reduce the roughening of the cemented carbide tool surface caused by cooling water, and if it is less than 0.1%, it is ineffective, and if it exceeds 1i10%, the strength will decrease, so 0.1 to 3 wt. A range of % is desirable.

以」二の組成面の検ｈ］で熱間鍛造工具として必要な高
温硬度１．’ｉ’、、Ｉ温靭性、肌荒れは解決するが、
熱亀裂に対する対策として次のことを見出した。The high-temperature hardness required for a hot forged tool was determined by 1. 'i', I temperature toughness and rough skin are resolved, but
We discovered the following as a countermeasure against thermal cracks.

ｉ’１ｌｌＬ間鍛重、熱同鍛造では金型表面に虫取する
熱亀裂は鍛造時の衝撃により一層成長する。従って表面
の亀裂発生を極力防止しなければならない。In heavy forging and thermal forging, the thermal cracks that form on the mold surface grow further due to the impact during forging. Therefore, cracks on the surface must be prevented as much as possible.

本発明では鍛造時の亀裂生成機構を鋭意検討した結果、
初期に発生する亀裂深さ、亀裂密ｒ、Ｚは結合相の凝固
粒度、ＣＯ／Ｎｉの均一分散、Ｃｒの濃度分布に影響さ
れることが判明した。In the present invention, as a result of intensive study of the crack generation mechanism during forging,
It was found that the initial crack depth, crack density r, and Z are influenced by the solidified particle size of the binder phase, the uniform dispersion of CO/Ni, and the concentration distribution of Cr.

本発明者等はＷＣ−Ｃｏ　−Ｎｉ　−Ｃｒ系合金は熱間
鍛造に適しているが、＋ｏｉＪ熱亀裂性を向上させる方
法を種々検旧した結果、焼結工程において焼結温度から
焼結体を急速に冷却することによって凝固粒度を制御で
きること、さらには凝固粒度が０．３　ｍｍ以下に制御
すると鍛造時に発生する熱亀裂を防止し得ることを見い
出したものである。The present inventors found that WC-Co-Ni-Cr alloys are suitable for hot forging, but as a result of examining various methods for improving +oiJ thermal cracking resistance, the inventors found that WC-Co-Ni-Cr alloys are suitable for hot forging. It was discovered that the solidified grain size can be controlled by rapidly cooling the steel, and that thermal cracks that occur during forging can be prevented by controlling the solidified grain size to 0.3 mm or less.

凝固粒度は、焼結体の冷却速度によって著しく影響を受
けるものであり、例えばガスの流入ｊに−や、発熱体と
被冷却物との間開等によって異ってくる。The solidified particle size is significantly affected by the cooling rate of the sintered body, and varies depending on, for example, the inflow of gas, the gap between the heating element and the object to be cooled, etc.

：１・ ゛例えば熱伝導反の大きいＨｅ　、　Ｈ２等を用いれば
冷却速度は大Ｉｌｌに向上しその結果０．１　ｍｍ以下
の凝固粒径をもつ超硬合金を得ることができる。:1. For example, by using He, H2, etc., which have high thermal conductivity, the cooling rate can be greatly improved, and as a result, a cemented carbide having a solidified grain size of 0.1 mm or less can be obtained.

用途によって、必要な凝固粒度も異なってくるが例えば
熱間塑性加工用工具としては０．１　ｍｍ以下の凝固粒
度をもつものの方が、特性としては良々Ｊとなる。The required solidified grain size varies depending on the application, but for example, as a tool for hot plastic working, a tool with a solidified grain size of 0.1 mm or less will have good J characteristics.

結合相の凝固粒度を０．３龍以」二にすると深い熱亀裂
が見られるようになり、さらに大きくすると大破する恐
れが出てくる。超硬合金の凝固粒度はイオンエツチング
あるいは化学的腐食法により容易に検出することが出来
る。第３Ｒ目こ超硬合金の顕微鏡による凝固組織を示し
た。濃淡の差は結晶方位によるものである。When the solidified particle size of the binder phase is increased to 0.3" or more, deep thermal cracks become visible, and when it becomes even larger, there is a risk of major damage. The solidified particle size of cemented carbide can be easily detected by ion etching or chemical corrosion. 3rd R shows the solidified structure of the cemented carbide under a microscope. The difference in shading is due to the crystal orientation.

このようにして得られた熱間、温間鍛造用塑性得た材料
を利用することができる。The thus obtained plastic material for hot and warm forging can be used.

に）実施例！ ＷＣ，Ｃｏ、　Ｎｉおよヒｃｒノ粉末を秤量し、ＷＣ−
１２＋１（量％Ｃｏ−８重軟％Ｎ　ｉ　−２′ｉＪＬ量
％Ｃｒとなるように配合し、混合粉砕を行った。これを
外径１００ｍｍ、１’）　（￥　４０　ｍｒｎ、６１ｉ
さ８０ｍｍの円筒状に成形し、真空炉中１０　”Ｔｏｒ
ｒにて５時間かけて、１４００℃に＋１１・温し、さら
に１時間その温度で保持した。保持後、炉りに装入した
架台を１気に加熱部より冷却部に移し、Ｎ２ガスを炉内
に導入し、超硬合金を１、気に急冷凝固させた合金（Ａ
）と、１４００℃にて１時１１１保持まで前記と同じ条
件でありその後加熱電源を切断した後、炉中で１０００
℃まで冷却しその後Ｎ２ガス′ｆ！：尋人して得た合金
（Ｂ）を製作した。) Examples! Weigh the WC, Co, Ni and Hcr powders and prepare the WC-
12+1 (amount % Co-8 heavy soft % Ni -2'i JL amount % Cr and mixed and pulverized. This was mixed and pulverized to an outer diameter of 100 mm, 1') (¥ 40 mrn, 61 i
Formed into a cylindrical shape with a length of 80 mm and heated in a vacuum furnace at 10” Torr.
The mixture was heated to +11° C. at 1400° C. for 5 hours and held at that temperature for an additional hour. After holding, the frame charged in the furnace was moved from the heating section to the cooling section in one go, N2 gas was introduced into the furnace, and the cemented carbide was mixed with 100% of the cemented carbide, and the alloy (A
) and held at 1400°C for 1 hour and 111 hours under the same conditions as above, after which the heating power was cut off and heated for 1000°C in the furnace.
℃ and then N2 gas 'f! : The alloy (B) obtained by Hirojin was manufactured.

かくの如くして得られた合金を鋼シャンクに圧入し加工
してベベルギヤー用鍛造金型を製作した。The alloy thus obtained was press-fitted into a steel shank and processed to produce a forging die for a bevel gear.

鍛造用材料を１１００℃に加熱し、鍛造圧２００ｔｏｎ
にてベベルギャーの？Ｉ＋＾１１す鍛造を行った。ダイ
ス鋼を金型とした場合は５０００ケでノを命となったが
、本発明の超硬合金（Ａ）は５万ケで寿命となり、また
（Ｂ）は１万個の寿命であった。超硬合金金型は従来の
ダイス鋼金型に比較して割高となるが、それを勘案する
と（Ｂ）ではその価値はないが、（Ａ’）では充分に超
硬合金を使用する価値があることがわかった。Heat the forging material to 1100℃ and apply a forging pressure of 200 tons.
Bevel gear? I+^11 Forged. When die steel was used as a mold, the life span was 5,000 pieces, but the life of the cemented carbide (A) of the present invention was 50,000 pieces, and the life of (B) was 10,000 pieces. . Cemented carbide molds are more expensive than conventional die steel molds, but if you take that into consideration, (B) is not worth it, but (A') is well worth using cemented carbide. I found out something.

この実施例で得られた超硬合金の凝固粒度をイオンエツ
チングによって調べた結果（Ａ）は平均１５０μｎＬで
あった。一方（Ｂ）は３００１ｉｎｔであった。ダイ寿
命は金型内口１１に発生する熱亀裂によるものであり、
さらに熱亀裂の表面エッヂ部にチッピングが発生し製品
形状不良および表面傷による寿命であった。The solidified particle size of the cemented carbide obtained in this example was examined by ion etching, and the average size (A) was 150 μnL. On the other hand, (B) was 3001 int. The life of the die is due to thermal cracks that occur in the mold inner opening 11.
Furthermore, chipping occurred at the surface edges of thermal cracks, resulting in poor product shape and surface scratches that shortened the product's lifespan.

本発明の超硬合金（Ａ）は亀裂深さが浅くかつ亀裂の開
き王台が小さいため長スを命となることがわかった。し
かし超硬合金（Ｂ）は亀裂が深くかつ亀裂部が開口し、
最後にチッピングが発生する。It has been found that the cemented carbide (A) of the present invention has a shallow crack depth and a small crack opening range, so long spans are essential. However, in cemented carbide (B), the cracks are deep and the cracks open,
Finally, chipping occurs.

また衝撃が大きい部分では亀裂が伸びて、超硬合金が割
れている。ダイス鋼の場合は肌荒れが著しく熱亀裂あ・
よびダイスの変形が見られ、製品形状、製品の表面状態
が悪化している。Also, in areas where the impact is large, the cracks extend and the cemented carbide breaks. In the case of die steel, the surface becomes rough and thermal cracks occur.
Deformation of the die was observed, and the product shape and surface condition were deteriorated.

実施例２ 実施例１と同様の方法にて第１表に示すような配合で超
硬合金を製作した。これを実施例１の（Ａ）と同様の方
法で急速冷却して、ベベルギヤー用鍛造金型を製作し温
間鍛造を行った。Example 2 A cemented carbide was produced in the same manner as in Example 1 with the formulations shown in Table 1. This was rapidly cooled in the same manner as in Example 1 (A), a forging die for a bevel gear was manufactured, and warm forging was performed.

第　１　表Table 1

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は各種超硬合金の硬度の温度特性を示すものであ
り、第２図は各種超硬合金の衝撃値の温度！１１′性を
示すものである。第３図は３０倍の顕微鏡写真を示す。 図中１−ＷＣ−１６Ｃｏ、　２−ＷＣ−８Ｃｏ−７Ｎｉ
−ＩＣｒ。 ８−ＷＣ−２５Ｃｏ、　４　・−ＷＣ−＋　５Ｃｏ、　
５−ＷＣ−１２ＣＯ１６−ＷＣ−１４Ｃｏ　−１，５Ｎ
ｉ　−０，５Ｃｒ　。 ７　・＝ＷＣ−１４Ｃｏ−４Ｎｉ−２Ｃｒ。 ０　２ｏθ　４θＯ〆ｏｏ　、５１θＯ邊濱（０ｃ） 第２図 し濫及（＝Ｃ）Figure 1 shows the temperature characteristics of hardness of various cemented carbide, and Figure 2 shows the temperature of impact value of various cemented carbide. It shows 11' character. Figure 3 shows a 30x micrograph. In the figure 1-WC-16Co, 2-WC-8Co-7Ni
-ICr. 8-WC-25Co, 4・-WC-+5Co,
5-WC-12CO16-WC-14Co-1,5N
i −0,5Cr. 7.=WC-14Co-4Ni-2Cr. 0 2oθ 4θO〆oo , 51θObehama (0c) Figure 2 and overflow (=C)

Claims (1)

【特許請求の範囲】 （り硬質相と結合相よりｌる超硬合金において、硬質相
がＷＣよりなり、結合相がＣｏ、　Ｎｉ、　Ｃｒ　より
なり、その量が１０〜４０重量％であり凝固結晶粒が０
．３　ｍｍ以下であることを特徴とする熱間塑性加工用
超硬合金。 （２）結合相が９９≧Ｃｏ／　Ｎ　ｉ≧Ｉの範囲であり
、かつＣｒがＯ，１〜３爪、ｉ＋’：％であることを特
徴とする特許市ｆ求の範囲第（１）項記載の熱間塑性加
工用超硬合金。 （３）硬質相と結合相よりなる超硬合金において、硬質
相がＷＣよりなり、結合相がＣｏ、　Ｎｉ、　Ｃｒ　Ｊ
：りなりその；ｔｌが１０〜４０重量％である超硬合金
の焼結過程において、焼結温度よりガス体によって急冷
することを特徴とする熱間塑性加工用超硬合金の製造法
。 （４）結合相が９９≧Ｃｏ／Ｎｉ≧１　の範囲であり、
かつＣｒが０．１〜３重量％であることを特徴とする熱
同塑性加工用超硬合金の製造法。[Claims] (In a cemented carbide comprising a hard phase and a binder phase, the hard phase is made of WC, the binder phase is made of Co, Ni, and Cr, and the amount thereof is 10 to 40% by weight, and the hardness is solidified. 0 grains
．． A cemented carbide for hot plastic working, characterized in that the diameter is 3 mm or less. (2) Range No. (1) of the patent city f request, characterized in that the binder phase is in the range of 99≧Co/Ni≧I, and Cr is O, 1 to 3 claws, i+':% Cemented carbide for hot plastic working as described in . (3) In a cemented carbide composed of a hard phase and a binder phase, the hard phase is composed of WC and the binder phase is Co, Ni, Cr J
A method for producing a cemented carbide for hot plastic working, characterized in that during the sintering process of a cemented carbide having a tl of 10 to 40% by weight, the cemented carbide is rapidly cooled from the sintering temperature using a gas body. (4) the bonding phase is in the range of 99≧Co/Ni≧1,
A method for producing a cemented carbide for thermoisoplastic working, characterized in that the content of Cr is 0.1 to 3% by weight.