JPS59126753A - Production of high-strength ferrous sintered parts - Google Patents

Abstract

PURPOSE:To obtain ferrous sintered parts having high strength without hot forging by subjecting iron powder consisting respectively of specified ratios of C powder and P powder added with a trace amt. of Ni, Mo, Mn, Cr and Sn to primary sintering then to shot peening and cold coining and subjecting the same further to secondary sintering. CONSTITUTION:Iron powder compounded with Fe-P alloy powder, electrolytic Cu powder and natural graphite powder so as to contain 2wt% Cu, 0.5wt% C and the balance Fe-P is prepaired. C in such iron powder is incorporated at 0.45- 0.9wt% and P powder at 0.1-0.5wt%. After 0.8wt% lead stearate is added as a lubricant to the compounded powder, the powder is mixed by using a V-shaped mixer and is compression-molded by using dies, whereby a powder molding is obtd. The molding is sintered in an inert gaseous atmosphere. The primary sintered body is subjected to shot peening then to cold coining in the dies, whereafter the sintered body is subjected to secondary sintering in an endothermic gaseous atmosphere and the intended high strength ferrous sintered parts are obtd.

Description

【発明の詳細な説明】 この発明は熱間鍛造を行なうことなく、高強度を有する
鉄系焼結部品の製造方法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing ferrous sintered parts having high strength without hot forging.

粉末冶金技術を用いた鉄系焼結部品は、生産性が高く、
かつ寸法精度が良く、又表面が清浄（スケールがなく光
輝面を有する）であるという特長を有しているので、広
い工業分野に晋及している。Iron-based sintered parts using powder metallurgy technology have high productivity.
It also has good dimensional accuracy and a clean surface (no scale and has a bright surface), so it is used in a wide range of industrial fields.

併し、焼結部品は多くの気孔を内部に有する為、強度特
に疲労強度が低いという欠点を有しておシ、高い強度を
有する鋼製鍛造部品に代わる焼結部品の出現が望まれて
いた。近年、焼結部品の気孔を、この部品に対して熱間
鍛造を行なうことによシ消滅させて、高い強度にした焼
結鍛造部品も実用化されるようになってきた。この焼結
鍛造部品は気孔がほとんどない為、高強度を有している
が、反面熱間鍛造を行なう為、焼結部品層・来の利点で
ある生産性、寸法精度が低下し、又疲労強度に最も重要
な影椿を有する表面付近には気孔が残留し易いという欠
点があった。However, since sintered parts have many pores inside, they have the disadvantage of low strength, particularly fatigue strength, and there is a desire for sintered parts to replace steel forged parts with high strength. Ta. In recent years, sintered forged parts that have high strength by eliminating pores in sintered parts by subjecting the parts to hot forging have come into practical use. This sintered forged part has almost no pores, so it has high strength, but on the other hand, because it is hot forged, the productivity and dimensional accuracy, which are the advantages of sintered part layers, decrease, and they also suffer from fatigue. There was a drawback that pores tend to remain near the surface where the camellia is most important for strength.

この発明は上記に濫゛み、熱間鍛造を行な−うことなく
、通常の焼結法で高い強度特に疲労強度を有する焼結部
品の製造方法を提供するものである。The present invention extends to the above and provides a method for manufacturing sintered parts having high strength, particularly fatigue strength, by a conventional sintering method without hot forging.

次に、この発明を冥施例に基づいて説明する。Next, this invention will be explained based on an example.

１００メツシユ（粒径１５０μ以下）の鉄：燐合金ｓ末
（０，３９６”　ｔ　含有ｔ　ルＦ′ｅ）、２ｏｏメツ
シユ（粒径７５μ以下）のぼ解枦Ｉ＋＋１（Ｃｕ）粉、
及び２００メツシユの天然！＃鉛（ｑ粉末を、虚盾比で
Ｃｕ２％、Ｃ０，５％残部がＦｅ−Ｐとなるように配合
し、さらに金型成形時の潤滑剤として、前述の九合物に
対し重量比で０．８％のステアリン酸亜鉛を投入した後
、この混合物をｖ５混合機を用いて６０分混合を行った
。100 meshes (particle size 150μ or less) of iron: phosphorus alloy s powder (0,396" t containing F'e), 200 meshes (particle size 75μ or less) of iron: phosphorus alloy I++1 (Cu) powder,
And 200 mesh natural! #Lead (q powder) is blended so that the imaginary shield ratio is Cu2%, C0.5% the balance is Fe-P, and as a lubricant during mold molding, After adding 0.8% zinc stearate, the mixture was mixed for 60 minutes using a V5 mixer.

次に、この混合粉末を金型を用いて４．８”／、４の加
圧力で圧縮成形して、第１図に実線で示した形状を有す
る粉末成形体１を得た。この粉末成形体１は全長１　＝
　９８．５ｕ、中心部の長さｎ１＝２０朋、この部の厚
さｔ１＝８ｍｘ、又両側のつかみ部の長さ１２　＝　２
４．２５闘いこの部の厚さＴ１−１９Ｈであシ、中心部
とつかみ部との曲面の半径ｒ−２１，５ＭＭである。Next, this mixed powder was compression molded using a mold at a pressure of 4.8"/4 to obtain a powder compact 1 having the shape shown by the solid line in FIG. Body 1 has total length 1 =
98.5u, length of the center part n1 = 20m, thickness of this part t1 = 8mx, and length of the gripping parts on both sides 12 = 2
4.25 The thickness of this part is T1-19H, and the radius of the curved surface between the center part and the grip part is r-21.5MM.

次に、この粉末成形体１を９５０°Ｃで６０分間エンド
サーミックガヌ雰囲気（Ｎ２　Ｊ＝ｒ３３％、ＣｏＪ＝
Ｆ２４％、残Ｎ２）中で焼結（第１次焼Ｍ）を行なった
。この第１次焼結体１をアークハイ）　０．３１　ａｍ
、カバレージ１００％でショットピーニングを行なった
後、更にこの第１次焼結体１に対し金型中で冷間コイニ
ング（プレス荷重は８ｔＯｎ／ｃｉ　）を実施した。Next, this powder compact 1 was heated at 950°C for 60 minutes in an endothermic Ganu atmosphere (N2 J=r33%, CoJ=
Sintering (first sintering M) was performed in F24%, balance N2). This primary sintered body 1 is arc high) 0.31 am
After shot peening with 100% coverage, the primary sintered body 1 was further subjected to cold coining in a mold (press load was 8 tOn/ci).

その結果、第１次焼結体１は第１図に破線で示すように
圧紬された。すなわち、中心部の板厚ｔ１＝８ｍＷｒが
ｔ２　＝　７　ｍとなり、又つかみ部の厚さＴ１＝１９
羽がＴ２　＝　１３　ｉｎとなった。As a result, the primary sintered body 1 was pressed as shown by the broken line in FIG. In other words, the plate thickness at the center t1 = 8 mWr becomes t2 = 7 m, and the thickness at the gripping part T1 = 19
The wings were now T2 = 13 inches.

次に、上記コイニング後の第１次焼結体１を、１１５０
°Ｃのエンドサーミックガス雰囲気中で６０分間２次焼
結を行ない第２次焼結体としてのテヌトピー７２（点線
で示す。）を得た。Next, the primary sintered body 1 after the above coining was heated to 1150
Secondary sintering was carried out for 60 minutes in an endothermic gas atmosphere at °C to obtain Tenutopi 72 (indicated by a dotted line) as a secondary sintered body.

第２図はこのテストピース２の表面部の兜孔５の分布状
況を示したものであり、表面６から約１Ｍまではほぼ完
全に気孔５がなく、内部４には多くの気孔５が残存して
いる。そして、このテストビーフ２の測定の結果は、表
面６で硬度がビツカーヌ（１０ｋｇ）で２７０、又密度
が７．６ｇ肩であシ、内部４で硬度がビッカース（１０
に９）で１９０、又密度が６．７　ｇＡ以上であった。Figure 2 shows the distribution of the pores 5 on the surface of this test piece 2. There are almost no pores 5 from the surface 6 to about 1M, and many pores 5 remain in the interior 4. are doing. The measurement results for Test Beef 2 show that the hardness at surface 6 is Vickers (10 kg), 270, the density is 7.6 g at the shoulder, and the hardness at internal 4 is Vickers (10 kg).
9) was 190, and the density was 6.7 gA or more.

上記のようにして形成されたテストビーフ２の強度評価
結果を表１に示す。Table 1 shows the strength evaluation results of Test Beef 2 formed as described above.

表１中、テスト材２の構造用鋼は５４Ｂｃである。In Table 1, the structural steel of test material 2 is 54Bc.

表１から明らかなように、テスト材１のテストビーフ２
は疲労強度で６の焼結鍛造材以上の強度を示している。As is clear from Table 1, test beef 2 of test material 1
shows a fatigue strength higher than that of sintered forged material with a rating of 6.

なお、表１のテスト材６の焼結鍛造材は以下の方法によ
シ製作したものである。The sintered forged material of test material 6 in Table 1 was manufactured by the following method.

１００メツシユの純Ｆｅ粉、２００メツシユの電Ｎ銅粉
及び２００メツシユの天然黒鉛粉を重量比でＣｕ２％、
Ｃ０６５％残部Ｆｅになるように配合し、この配合材に
対し０．８％のステアリン酸亜鉛を金型成形時の潤滑剤
として投入した。100 mesh pure Fe powder, 200 mesh N copper powder and 200 mesh natural graphite powder with Cu2% by weight,
The mixture was blended to have 65% CO and the balance was Fe, and 0.8% zinc stearate was added to this blend as a lubricant during molding.

そして、上記配合剤をｖ１型混合機を用いて６０分間混
合した後、この混合粉末を金型を用いて４．８ｔｏｎ、
ｌｄの加圧力で第１図に実線で示すテストビーフ１と同
じ形の粉末成形体を得た後、この粉末成形体ｅ１１５０
°Ｃのエンドサーミックガス雰囲気中で加熱し、ただち
に金型を用いて９酬」の傭東で熱間に造を行ない、形状
がテストピース２と同じ焼結鍛造体を製作した。After mixing the above ingredients for 60 minutes using a V1 mixer, 4.8 tons of this mixed powder was mixed using a mold.
After obtaining a powder compact with the same shape as Test Beef 1 shown by the solid line in Fig. 1 with a pressing force of ld, this powder compact e1150
It was heated in an endothermic gas atmosphere at °C, and immediately hot-molded using a mold with a 9-metal mold to produce a sintered forged body having the same shape as test piece 2.

次に、この実施例における炭、素Ｃ及び燐Ｐの作用につ
いて説明する。Next, the effects of carbon, element C, and phosphorus P in this example will be explained.

炭素Ｃは鋼材の硬さおよび強度を向上させる元素である
事は一般的に知られている通シである。It is generally known that carbon C is an element that improves the hardness and strength of steel materials.

この実施例において、Ｃの量が０．４５％以下ではテス
トビーフ２の表面６の硬さとして、ＨＶ（１０に９）２
００以上を得るには、高価なＣｕ、Ｎｉ、Ｍｏ、　Ｍｎ
及びＮ１等の元素を多量に添加する必要があり、経済的
でな゛い。そして、表面６の硬さがＨｖ（１０ｋｑ）２
００以下では高い疲労強度が得られないので、Ｃの量は
０．４５％以上とする必要がある。一方、Ｃの量が０．
９％以上になると、組織中にセメンタイトが著しく析出
するようになり、疲労強度が逆に低下する。従って、Ｃ
量は０．４５〜０，９％が過当である。In this example, when the amount of C is 0.45% or less, the hardness of the surface 6 of the test beef 2 is HV (9 to 10) 2.
To obtain 00 or more, expensive Cu, Ni, Mo, Mn
It is necessary to add a large amount of elements such as N1 and N1, which is not economical. And the hardness of the surface 6 is Hv (10kq)2
If it is less than 0.00, high fatigue strength cannot be obtained, so the amount of C needs to be 0.45% or more. On the other hand, the amount of C is 0.
If it exceeds 9%, cementite will precipitate significantly in the structure, and the fatigue strength will conversely decrease. Therefore, C
An appropriate amount is 0.45 to 0.9%.

なお、Ｃｕ、Ｎｉ、ＭＯｌＭｎ　ｌｌｔ、びＣｒ等ノ元
素は、Ｃのみでは不足する嫂さ、強度を拙う為の元素で
あシ、使用目的によシ過当瓜を選択して除却するのは通
常の焼結合金の場合と同様である。In addition, elements such as Cu, Ni, MOlMnllt, and Cr are elements that improve the strength and strength of C alone, so it is best to select and remove excess melons depending on the purpose of use. This is the same as in the case of ordinary sintered alloys.

燐（Ｐｉはこの実施例において重もポルな元素であシ、
次のような作用を有している。Phosphorus (Pi is a heavy element in this example)
It has the following effects.

■　１次焼結においては、焼結を促進し、かつ低温焼結
で焼結体の硬さを著しく上昇させる事なく粉末の結合を
強化する。この結果、−次焼結に続くショットピーニン
グによシ粉末成形体１０表面から０．５緒以上までを略
真密度（気孔５がない状態）にする事ができる。ちなみ
に、Ｐを添加しないテストビーフを作成し、−次焼結に
続くショットピーニングを行なったところ、テストビー
フの隅部に欠けを生じた。又、上記１次焼結を１１００
℃で６０分間実施したもののショットピーニング後の真
密度の部分は、表面から０．１〜Ｄ、１５ｊｌｊｆであ
り、この実施例のテストピース２の０．５緒と比較する
と非常に少なかった。■ In the primary sintering, sintering is promoted and the low temperature sintering strengthens the bonding of the powder without significantly increasing the hardness of the sintered body. As a result, by the shot peening subsequent to the second sintering, it is possible to make the powder compact 10 from the surface up to 0.5 mm or more approximately true density (a state in which there are no pores 5). Incidentally, when test beef without P added was prepared and shot peening was performed following the -second sintering, chipping occurred at the corners of the test beef. In addition, the above primary sintering was performed at 1100
The true density after shot peening for 60 minutes at ℃ was 0.1-D from the surface and 15jljf, which was very small compared to 0.5D of test piece 2 of this example.

■　２次焼結はテストピース２全体の焼結を完全に行な
うものであるが、この場合にショットピーニングおよび
冷間コイニングによシ略真密度になった表面部分のマイ
クロクラックを完全に焼結する事が重要であり、このク
ラックが桟留すると、テストピース２の疲労強度向上の
効果が著しく失われる。Ｐはテストビーフ２の表面部分
のマイクロクラックを完全に焼結する性質を有している
。■ Secondary sintering is to completely sinter the entire test piece 2, but in this case, shot peening and cold coining completely sinter the microcracks on the surface that has reached approximately true density. It is important to do this, and if this crack becomes anchored, the effect of improving the fatigue strength of the test piece 2 will be significantly lost. P has the property of completely sintering the microcracks on the surface of the test beef 2.

ちなみに、Ｃｕ　２　％、０．５％ＣＱ部Ｆｅの瑣量比
を有しＰを含有しない粉末を１１００°Ｃで６０分間１
次焼結後、以後の工程をこの実施例と全く同じ方法で製
作したテストビーフの引張強さは７０にり／ｌ１１ｍ’
であり、略この実施例のテストピース２と差がなかった
が、疲労強度が２４ｋｑ／ＩＩＬ［１１″と著しく低い
ものであった。Incidentally, a powder containing no P and having a trivial ratio of Cu 2 %, 0.5% CQ part Fe was heated at 1100°C for 60 minutes.
After the next sintering, the tensile strength of the test beef produced using the same method as in this example was 70 mm/l11 m'
Although there was almost no difference from test piece 2 of this example, the fatigue strength was extremely low at 24 kq/IIL [11''.

そして、テストの結果Ｐの址としては、粉末成形体１（
テストビーフ２）の全量に対して０．１％以下では不充
分であり、逆に０．５％以上を加えるト、Ｆ’ｅ−Ｃ−
Ｐ糸の共晶であるヌテダイトが析出し易くなって、疲労
強度の低下が起こる。従って、Ｐの量は粉末成形体１に
対して０．１〜０．５％が適当である。As a result of the test, P powder compact 1 (
It is insufficient to add 0.1% or less to the total amount of test beef 2), and conversely, adding 0.5% or more to the total amount of F'e-C-
Nutedite, which is a eutectic of P yarn, tends to precipitate, resulting in a decrease in fatigue strength. Therefore, the appropriate amount of P is 0.1 to 0.5% based on the powder compact 1.

次に、通常使用される焼結合金製のほとんどの部品は、
最表面部に応力が果申し易い。この疲労の起点部分にな
）易い表面部の強度を向上させるには、冷間加工と雰囲
気焼結である為の表面部の清浄性（焼結鍛造は熱間鍛造
であるため表面部の清浄性が悪い）を加味しても、表面
の密度を入６ｇ／ｃｄ以上にする必要がある。そして、
内部密度も６．７ｇ／ａｌ以下では表面部の応力負担が
著しく大きくなる為、内部密度としても６．７　ｇ／ｄ
以上が必要である。この実施例のテストピース２はその
表面密度が乙６ｇ／７以上であシ、かつその内部密度が
６．７ｇＡ以上になっているので、上記の条件を十分満
足している。Next, most commonly used parts made of sintered alloys are
Stress tends to be felt on the outermost surface. In order to improve the strength of the surface area, which tends to be the starting point of fatigue, it is necessary to maintain the cleanliness of the surface area due to cold working and atmosphere sintering. Even if we take into account the negative effects (poor properties), the surface density needs to be at least 6 g/cd. and,
If the internal density is less than 6.7 g/al, the stress burden on the surface becomes significantly large, so the internal density is also 6.7 g/d.
The above is necessary. The test piece 2 of this example has a surface density of 6 g/7 or more and an internal density of 6.7 gA or more, so it fully satisfies the above conditions.

又、通常の高強度材料は硬度が高い為に一般的にはＯａ
械加工性が良くないが、この実施例の焼結合金は１次焼
結後でショットピーニング前に機械加工を行なうことが
可能であシ、機械加工性が落ちることもない。In addition, ordinary high-strength materials have high hardness, so they generally have Oa
Although machinability is not good, the sintered alloy of this example can be machined after primary sintering and before shot peening, and machinability does not deteriorate.

この発明は上記のように、重量比で戻水０．４５〜０，
９０％、燐０．１〜０，５％の粉末及び銅、ニッケル、
七ルプデン、マンガン、クロムおよび錫のうち少くとも
一種を倣加に加えた鉄の粉末を予備焼結してできた部品
にショットピーニングと冷間コイニングを行ない史に二
回目の焼結をして、高強度鉄系焼結部品を製造すること
としたことによル、表面部の密度を乙６　ｇＡｄ以上、
又内部の密度を６．７　ｇ／ｄ以上にして、熱間焼結鍛
造材以上の疲労強度を有し、かつ寸法精度や表面清浄度
の極めて優れた高強度鉄糸咬結部品を得ることができる
。As mentioned above, this invention has a weight ratio of 0.45 to 0 return water,
90%, 0.1-0.5% phosphorus powder and copper, nickel,
Parts made by pre-sintering iron powder to which at least one of hexafluoride, manganese, chromium and tin has been added are subjected to shot peening and cold coining, and then sintered for the second time in history. By manufacturing high-strength iron-based sintered parts, the density of the surface area was increased to 6 gAd or more.
Also, to obtain a high-strength iron thread-bound part with an internal density of 6.7 g/d or more, which has a fatigue strength higher than that of hot sintered forged materials, and has extremely excellent dimensional accuracy and surface cleanliness. I can do it.

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

図はこの発明により製造した粉末成形体（テストビーフ
）の正面図、第２図は第１図のテストピース（点線部）
の１−１線ｆｒ面図である。 １・・・粉末成形体（１次焼結体） ２・・・テストピース（高強度鉄系焼結部品）出　　願
　　人　　トヨタ自動車株式会社代　　　理　　　人　
　　弁理士　岡　　１）　英　　彦後図面無し 第１図 第　２　図 ００ｕ 手続補正書（力”へ９ 昭和タフ年　２月７０日 特許庁長官　若’Ｌ和夫殿　　ス：す １　事件の表示 昭和タフ年　酋　評　願第１．ｊ２２紋号４１件との関
係　特許出願人 ４代理人 輛３１１４The figure is a front view of the powder compact (test beef) produced according to the present invention, and Figure 2 is the test piece of Figure 1 (dotted line).
It is a 1-1 line fr view of . 1...Powder compact (primary sintered compact) 2...Test piece (high strength iron-based sintered part) Applicant: Toyota Motor Corporation Agent
Patent Attorney Oka 1) Hidehiko No drawings Figure 1 Figure 2 Figure 00u Procedural amendment (to force) 9 February 70, Showa Tuff Director General of the Patent Office Mr. Waka'L Kazuo S:S1 Display of the case Showa Tuff year No. 1.Relationship with 41 cases of J22 Crest Number of Patent Applicants 4 Agents 3114

Claims (1)

【特許請求の範囲】[Claims] クロム並びに錫の粉末のうち少くとも一種を加是た鉄粉
を１次焼結し、この−次焼結部品にシーットピーニング
と冷間コイニン夛を行ないさらに２次焼結したことを特
徴とずぶ高強度鉄系焼結部品の製造方法。It is characterized by primary sintering of iron powder to which at least one of chromium and tin powders has been added, sheet peening and cold sintering of this primary sintered part, and further secondary sintering. A manufacturing method for extremely high-strength iron-based sintered parts.