JP2737358B2 - Sintering forging method - Google Patents
Sintering forging methodInfo
- Publication number
- JP2737358B2 JP2737358B2 JP2122020A JP12202090A JP2737358B2 JP 2737358 B2 JP2737358 B2 JP 2737358B2 JP 2122020 A JP2122020 A JP 2122020A JP 12202090 A JP12202090 A JP 12202090A JP 2737358 B2 JP2737358 B2 JP 2737358B2
- Authority
- JP
- Japan
- Prior art keywords
- sintered body
- gas
- sintering
- open pores
- heating furnace
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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- Powder Metallurgy (AREA)
Description
【発明の詳細な説明】 産業上の利用分野 本発明は粉末鍛造方法に関するものであり、特に、予
備成形体を焼結した後鍛造する焼結鍛造方法に関するも
のである。Description: TECHNICAL FIELD The present invention relates to a powder forging method, and more particularly to a sintering forging method in which a preform is sintered and then forged.
従来の技術 粉末鍛造方法の一種として焼結鍛造方法が知られてい
る。焼結鍛造方法は、例えば『焼結機械部品−その設計
と製造−（日本粉末冶金工業会編著，株式会社技術書院
発行）』に記載されているように、まず、鉄粉，黒鉛粉
等の原料粉末を混合し、粉末成形プレス装置等により加
圧して予備成形体を形成する。次に、予備成形体を加熱
炉で加熱して、焼結体を形成する。加熱炉内には、一酸
化炭素（CO），水素（H2）および窒素（N2）と二酸化炭
素（CO2），水（H2O）等の不純物とを含むRXガス（商品
名）や、水素および窒素と水等の不純物とを含むAXガス
（商品名）等の還元性ガスを充満させ、この還元性雰囲
中で焼結を行うことにより、予備成形体の酸化物が還元
され、良質な焼結体を得ることができる。また、還元性
ガスを用いず、窒素ガスを充満させて加熱しても、焼結
体の酸化を防止することができる。焼結体を焼結直後あ
るいは再加熱した後、加熱炉から取り出して鍛造する。
焼結体は、その内部に、予備成形時よりは小さくなるも
のの多数の気孔を内包しており、これら気孔の中には焼
結体の表面に開口した開気孔も含まれている。鍛造によ
ってこれら気孔を消滅させ、製品の密度を真空度まで上
昇させれば一連の焼結鍛造工程が終了する。2. Description of the Related Art A sintering forging method is known as a kind of powder forging method. As described in, for example, “Sintering Machine Parts-Design and Manufacturing-(edited by the Japan Powder Metallurgy Association, published by Technical Shoin Co., Ltd.)”, the sintering forging method firstly uses iron powder, graphite powder or the like. The raw material powders are mixed and pressed by a powder molding press or the like to form a preform. Next, the preform is heated in a heating furnace to form a sintered body. RX gas containing carbon monoxide (CO), hydrogen (H 2 ) and nitrogen (N 2 ) and impurities such as carbon dioxide (CO 2 ) and water (H 2 O) in the heating furnace (trade name) Or a reducing gas such as AX gas (trade name) containing impurities such as hydrogen and nitrogen and water, and sintering in this reducing atmosphere, the oxide of the preformed body is reduced. As a result, a high-quality sintered body can be obtained. In addition, even if a nitrogen gas is filled and heated without using a reducing gas, oxidation of the sintered body can be prevented. Immediately after sintering or after reheating, the sintered body is taken out of the heating furnace and forged.
The sintered body contains a large number of pores therein, though smaller than in the preforming, and these pores include open pores opened on the surface of the sintered body. If the pores are eliminated by forging and the density of the product is raised to a degree of vacuum, a series of sintering and forging steps is completed.
発明が解決しようとする課題 しかしながら、上記焼結鍛造工程において、加熱炉内
の還元性ガス中に、大気中での発火下限界組成以上の水
素，一酸化炭素等の可燃性ガスが含まれている場合に
は、焼結体を加熱炉から取り出したときに、第５図に示
すように、焼結体40表面の開気孔42内に充満している可
燃性ガスが大気中の酸素と結合して発火し、火炎が開気
孔42内部へ伝播することがあるという問題があった。水
素および一酸化炭素の酸化反応は、下記の（１）および
（２）式に示すようにガスの容積の収縮を伴う反応であ
るため、大気が次々に開気孔の奥部へ進入し、火炎が伝
播して焼結体が内部まで酸化してしまうのである。Problems to be Solved by the Invention However, in the sintering and forging process, the reducing gas in the heating furnace contains a combustible gas such as hydrogen or carbon monoxide having a lower ignition limit composition in the atmosphere or more. In this case, when the sintered body is taken out of the heating furnace, as shown in FIG. 5, the combustible gas filling the open pores 42 on the surface of the sintered body 40 is combined with oxygen in the atmosphere. Then, there is a problem that the flame may propagate into the open pores 42. Since the oxidation reaction of hydrogen and carbon monoxide is a reaction involving the contraction of the gas volume as shown in the following equations (1) and (2), the air successively enters the deep part of the open pores, and the flame Is propagated and the sintered body is oxidized to the inside.
H2＋1/2O2→H2O ……（１） CO＋1/2O2→CO2 ……（２） 一方、窒素ガス中で加熱を行った場合でも、窒素ガス
そのものは不燃性であるが、原料粉末には成形時の潤滑
剤として例えばステアリン酸亜鉛（Zn（C17H35COO）2:s
t−Znと称する）等が混合されるため、加熱時に潤滑剤
から可燃性ガスが蒸発して気孔に集まり、特に開気孔に
集まった可燃性ガスが大気中の酸素と結びついて発火
し、火炎が伝播するという問題があった。H 2 + 1 / 2O 2 → H 2 O (1) CO + 1 / 2O 2 → CO 2 (2) On the other hand, even when heating is performed in nitrogen gas, nitrogen gas itself is nonflammable, For example, zinc stearate (Zn (C 17 H 35 COO) 2 : s)
flammable gas evaporates from the lubricant during heating and collects in the pores. In particular, the flammable gas collected in the open pores combines with oxygen in the atmosphere and ignites, causing a flame. There was a problem that was propagated.
このように焼結体内部の原料粉末が酸化されると粉末
同士が十分結合しないため、鍛造後に開気孔が切欠とし
て製品に残り、製品の強度が低くなって品質が低下す
る。その一例を第６図に光学顕微鏡写真で示す。これは
焼結体40の一部を切断して研摩した面の金属組織を示す
写真であるが、焼結体40の表面から相当深い部分まで多
くの亀裂（細い黒い線として現れている）が生じている
のが判る。また、第７図は同じ焼結体40の静的破断面の
走査電子顕微鏡写真であるが、焼結体40の内部の破断面
は第９図の拡大写真から一層明らかなように、擬劈開面
となっているのに対し、表面から約0.5mmの深さまでの
部分には第８図から一層明らかなように未結合部が分布
しているのが判る。第７図においては、例えば、直線a,
bの交点（正確には直線ａと直線ｂとをそれぞれ写真内
へ延長した２本の延長線の交点）、直線c,dの交点、直
線e,fの交点等の位置に未結合部が見られ、第８図にお
いては直線g,hの交点、直線i,jの交点等の位置に未結合
部が見られる。When the raw material powder in the sintered body is oxidized as described above, the powders are not sufficiently bonded to each other, so that open pores remain in the product as notches after forging, and the strength of the product is reduced and the quality is reduced. One example is shown by an optical microscope photograph in FIG. This is a photograph showing the metal structure of the surface obtained by cutting and polishing a part of the sintered body 40. Many cracks (appearing as thin black lines) from the surface of the sintered body 40 to a considerably deep part are shown. You can see that it is occurring. FIG. 7 is a scanning electron micrograph of the static fracture surface of the same sintered body 40. The fracture surface inside the sintered body 40 is pseudo-cleaved, as is clear from the enlarged photograph of FIG. In contrast to the surface, unbonded portions are found to be distributed in the portion from the surface to a depth of about 0.5 mm, as is clear from FIG. In FIG. 7, for example, a straight line a,
An unjoined portion is located at the intersection of b (exactly, the intersection of two extended lines obtained by extending the straight line a and the straight line b into the photograph), the intersection of the straight lines c and d, and the intersection of the straight lines e and f. In FIG. 8, unconnected portions are seen at positions such as the intersection of the straight lines g and h and the intersection of the straight lines i and j.
本発明は上記問題に鑑み、焼結体が鍛造のために大気
中に取り出された場合の開気孔における火炎の伝播を阻
止することにより、焼結体内部の酸化を防止得る焼結鍛
造方法を得ることを課題として為されたものである。In view of the above problems, the present invention provides a sintering forging method capable of preventing oxidation of the inside of a sintered body by preventing the propagation of a flame in open pores when the sintered body is taken out into the atmosphere for forging. The task was to get it.
課題を解決するための手段 そして、本発明は、原料粉末を成形して予備成形体を
形成し、その予備成形体を加熱炉内で加熱して焼結体と
した後、その焼結体を鍛造して製品を形成する焼結鍛造
方法において、焼結体の加熱炉からの取出しに際して、
その焼結体の周囲を真空雰囲気とすることによりその焼
結体の開気孔内を脱気し、その脱気された開気孔内に不
発火性ガスを充満させた後、焼結体を大気中へ取り出す
ことを特徴とするものである。Means for Solving the Problems And the present invention is to form a pre-formed body by molding the raw material powder, heat the pre-formed body in a heating furnace to form a sintered body, and then, the sintered body In the sintering forging method of forming a product by forging, when taking out the sintered body from the heating furnace,
The inside of the open pores of the sintered body is degassed by setting the periphery of the sintered body to a vacuum atmosphere, and after filling the non-ignitable gas in the degassed open pores, the sintered body is released to the atmosphere. It is characterized by being taken out inside.
なお、「不発火性ガス」とは大気中で酸素と結合しな
い窒素等の不燃性ガス、あるいは酸素と結合しても発火
しないガス、例えば、不燃性ガスに大気中での発火下限
界組成以下の可燃性ガスが混入したガス等を指すものと
する。この混合ガスは、発火下限界組成以下では、部分
的に反応は進行するが、全面的発火すなわち火炎の伝播
は起こらない。The term "non-flammable gas" refers to a non-flammable gas such as nitrogen that does not combine with oxygen in the atmosphere, or a gas that does not ignite even when combined with oxygen. Gas, etc. mixed with flammable gas. When the mixed gas has a composition lower than the lower ignition limit composition, the reaction partially proceeds, but the entire ignition, that is, the propagation of the flame does not occur.
作用 本発明に係る焼結鍛造方法においては、焼結体の開気
孔内が脱気され、その脱気された開気孔内に不発火性ガ
スが充満させられた後に焼結体が取り出されるため、開
気孔内のガスが大気中で発火して焼結体の内部まで酸化
することが防止される。前述のように、焼結が還元性ガ
ス中において行われ、焼結体の開気孔内に発火下限界組
成以上の水素，一酸化炭素等の可燃性ガスが含まれてい
る場合や、原料粉末に含まれている潤滑剤から焼結のた
めの加熱時に可燃性ガスが蒸発して開気孔内に存在して
いる場合でも、真空脱気によりそれら可燃性ガスが脱気
され、代わりに不発火性ガスが充満させられるのであ
る。In the sinter forging method according to the present invention, the inside of the open pores of the sintered body is degassed, and the sintered body is taken out after the non-ignitable gas is filled in the deaerated open pores. In addition, the gas in the open pores is prevented from igniting in the atmosphere and being oxidized to the inside of the sintered body. As described above, the sintering is performed in a reducing gas, and the open pores of the sintered body contain a flammable gas such as hydrogen, carbon monoxide or the like having a lower limit composition than the lower limit of ignition. Even if the flammable gas evaporates from the lubricant contained in the sintering during heating for sintering and exists in the open pores, the flammable gas is degassed by vacuum degassing and, instead, no fire occurs The natural gas is filled.
例えば、加熱炉内を複数に分割し、加熱室，パージ
室，脱気室および置換室等を設け、加熱室内を還元性ガ
スの雰囲気として予備成形体を焼結した後、開気孔内の
ガスを不発火性ガスに置換することが可能である。すな
わち、まず、焼結後に焼結体をパージ室に移動させ、パ
ージ室内の還元性ガスを窒素等の不燃性ガスで置換す
る。このときにはまだ、焼結体の開気孔内には焼結室内
の還元性ガスや潤滑剤から蒸発したガスが充満している
が、脱気室において焼結体を真空脱気することにより、
パージガスと共に焼結体の開気孔内に充満しているガス
も抜く。そして、置換室において新たに窒素等の不発火
性ガスを送り込み、焼結体の開気孔内に不発火性ガスを
充満させる。このように開気孔内に不発火性ガスを充満
させた状態で焼結体を加熱炉から取り出せば、開気孔内
での火炎の伝播を防止することができ、焼結体内部の酸
化を防止することができる。For example, the inside of the heating furnace is divided into a plurality of parts, a heating chamber, a purge chamber, a degassing chamber, a replacement chamber, etc. are provided. Can be replaced with a non-ignitable gas. That is, first, after sintering, the sintered body is moved to the purge chamber, and the reducing gas in the purge chamber is replaced with a nonflammable gas such as nitrogen. At this time, the open pores of the sintered body are still filled with the reducing gas and the gas evaporated from the lubricant in the sintering chamber, but by evacuating the sintered body in vacuum in the degassing chamber,
The gas filling the open pores of the sintered body is also removed together with the purge gas. Then, a new non-ignitable gas such as nitrogen is sent into the replacement chamber to fill the open pores of the sintered body with the non-ignitable gas. If the sintered body is taken out of the heating furnace with the open pores filled with the non-ignitable gas, the propagation of the flame in the open pores can be prevented, and the oxidation inside the sintered body can be prevented. can do.
上記開気孔内に充満させる不発火性の雰囲気ガスとし
て、不燃性ガスと発火下限界組成以下の可燃性ガスとの
混合ガス、例えば窒素ガスに少量の水素ガスおよび一酸
化炭素ガスを混合したもの等を用いれば、混合ガス中の
可燃性ガスが焼結体の還元作用を為すとともに、加熱終
了後に焼結体を加熱炉から取り出したときの火炎の伝播
を回避し得る。混合ガス中の可燃性ガスは発火下限界組
成以下であるため、大気中の酸素と結合するものの、発
火して火炎が伝播し、焼結体内部まで酸化することはな
いのである。なお、焼結体表面からごく浅い部分の酸化
はショットピーニング等の後処理によって容易に解消さ
れるため差支えなく、火炎が伝播して焼結体の内部まで
酸化することが防止されればよい。As a non-flammable atmosphere gas to be filled in the open pores, a mixed gas of a non-flammable gas and a flammable gas having a lower ignition limit composition or less, for example, a mixture of a small amount of hydrogen gas and carbon monoxide gas in nitrogen gas By using such a method, the combustible gas in the mixed gas serves to reduce the sintered body, and the propagation of flame when the sintered body is taken out of the heating furnace after the completion of heating can be avoided. Since the combustible gas in the mixed gas has a composition equal to or lower than the lower ignition limit composition, the combustible gas is combined with oxygen in the atmosphere, but is ignited, the flame propagates, and the inside of the sintered body is not oxidized. Oxidation of a very shallow portion from the surface of the sintered body can be easily eliminated by post-processing such as shot peening, so that there is no problem as long as the flame is prevented from propagating to oxidize the inside of the sintered body.
上記発火下限界組成以下の可燃性ガスとしてメタン
（CH4）ガスを用いることができる。メタンガスは還元
性を有するとともに、（３）式に示すように、大気中で
酸素と結合してもその容積が減少しないため、開気孔の
開口周辺で発火しても火炎の焼結体内部への伝播が抑制
される。Methane (CH 4 ) gas can be used as a combustible gas having a lower ignition limit composition or less. Methane gas has a reducing property and, as shown in equation (3), does not decrease its volume even when combined with oxygen in the atmosphere. Therefore, even if it ignites around the opening of the open pore, it enters the sintered body of the flame. Is suppressed.
CH4＋2O2→CO2＋2H2O ……（３） 発明の効果 上記のように、大気中に取り出した際の開気孔内にお
ける火炎の伝播を防止し、焼結体内部の酸化を防止する
ことにより、鍛造によって原料粉末を確実に金属結合さ
せることができる。したがって、鍛造後の製品の表層部
に原料粉末の未結合部が残留することを防止し得、強度
が高く、高品質の製品を得ることができる。CH 4 + 2O 2 → CO 2 + 2H 2 O (3) Effect of the Invention As described above, the propagation of flame in the open pores when taken out to the atmosphere is prevented, and the oxidation inside the sintered body is prevented. Thus, the raw material powder can be securely metal-bonded by forging. Therefore, it is possible to prevent the unbonded portion of the raw material powder from remaining on the surface layer of the forged product, and to obtain a high-strength, high-quality product.
また、本発明によれば、焼結時に開気孔内に発火性ガ
スが充満しても、これが脱気されて、代わりに不発火性
ガスが充満させられるため、焼結時に水素や一酸化炭素
の濃度を高くして十分に強い還元雰囲気にしたり、原料
粉末に含ませる潤滑剤を加熱時に可燃性ガスが蒸発する
ものとしたりすることができ、これらの点からも高品質
の製品を得ることができる。Further, according to the present invention, even if the open pores are filled with the ignitable gas at the time of sintering, they are degassed and filled with the non-ignitable gas instead. To obtain a sufficiently strong reducing atmosphere by increasing the concentration of flammable gas, or to allow the lubricant contained in the raw material powder to evaporate flammable gas when heated, and to obtain high quality products from these points as well. Can be.
実施例 以下、本発明の焼結鍛造方法により自動車のエンジン
用コンロッドを製造する場合の実施例を説明する。EXAMPLES Hereinafter, examples in which a connecting rod for an engine of an automobile is manufactured by the sintering and forging method of the present invention will be described.
まず、原料粉末として、−80＃のアトマイズ鉄粉（F
e），−200＃の電解銅粉（Cu），鱗片状黒鉛粉末（Gr）
および潤滑剤としてステアリン酸亜鉛（st−Zn）を用意
し、重量比でCu2％,Gr0.6％,st−Zn0.8％，残りFeの割
合で配合し、Ｖ型混粉機で30分間混合する。First, -80 # atomized iron powder (F
e), -200 # electrolytic copper powder (Cu), flaky graphite powder (Gr)
And zinc stearate (st-Zn) is prepared as a lubricant, and it is blended by weight ratio of Cu2%, Gr0.6%, st-Zn0.8%, and the remaining Fe. Mix.
次に、混合した原料粉末を油圧プレスにより面圧5t/c
m2で圧縮し、予備成形体を成形する。Next, the mixed raw material powder was pressed with a hydraulic press to a surface pressure of 5 t / c.
Compress at m 2 to form a preform.
さらに、この予備成形体を第１図に示す加熱炉10に入
れる。加熱炉10内はそれぞれ独立した予熱室12,焼結室1
4,パージ室16,脱気室18および置換室20が設けられてお
り、図示しない移送装置によって予備成形体が移送され
るようになっている。Further, this preform is put into a heating furnace 10 shown in FIG. Heating furnace 10 has independent preheating chamber 12 and sintering chamber 1
4, a purge chamber 16, a degassing chamber 18, and a replacement chamber 20 are provided, and a preform is transferred by a transfer device (not shown).
まず、室内温度が800℃の予備室12において予備成形
体を予熱し、RXガス（H2,CO,N2）を充満させた焼結室14
において1150℃で10分間焼結する。これにより予備成形
体が焼結体22となり、次に、焼結体22をパージ室16へ移
動させ、RXガスをパージガスとしての窒素ガス（N2）で
置換する。焼結体22をパージ室16へ移動させるのに伴っ
て焼結室14内のRXガスがパージ室16へ流れ込むが、これ
を窒素ガスで置換するのである。続いて、焼結体22を脱
気室18へ移動させ、脱気室18内の真空度を10-1Torr以下
として１分間の真空脱気を行う。焼結体22の内部には多
数の気孔が形成されており、表層部の気孔は外部へ開口
した開気孔24となっていて、これら開気孔24内には焼結
室14内のRXガスが充満しているが、真空脱気を行うこと
により開気孔24内のRXガスが吸い出される。さらに、焼
結体22を置換室20に移動させた上、置換室20に純窒素ガ
スを供給し、第２図に示すように、焼結体22内の開気孔
24に窒素ガスを充満させる。そして、この状態で焼結体
22を加熱炉10から取り出す。なお、焼結体22はパージ室
16,脱気室18および置換室20においても加熱し続ける。First, a preformed body is preheated in a prechamber 12 having a room temperature of 800 ° C., and a sintering chamber 14 filled with RX gas (H 2 , CO, N 2 ).
At 1150 ° C for 10 minutes. As a result, the preformed body becomes the sintered body 22, and then the sintered body 22 is moved to the purge chamber 16, and the RX gas is replaced with nitrogen gas (N 2 ) as a purge gas. The RX gas in the sintering chamber 14 flows into the purge chamber 16 as the sintered body 22 is moved to the purge chamber 16, and the RX gas is replaced with nitrogen gas. Subsequently, the sintered body 22 is moved to the degassing chamber 18, and the degree of vacuum in the degassing chamber 18 is set to 10 -1 Torr or less, and vacuum degassing is performed for one minute. A large number of pores are formed inside the sintered body 22, and the pores in the surface layer are open pores 24 that open to the outside.In these pores 24, the RX gas in the sintering chamber 14 is filled. Although it is full, RX gas in the open pores 24 is sucked out by performing vacuum degassing. Further, after the sintered body 22 is moved to the replacement chamber 20, pure nitrogen gas is supplied to the replacement chamber 20, and as shown in FIG.
Fill 24 with nitrogen gas. And in this state the sintered body
22 is taken out of the heating furnace 10. The sintered body 22 is located in the purge chamber.
16, the heating is continued in the degassing chamber 18 and the replacement chamber 20.
加熱炉10から取り出した焼結体22を、直ちに面圧8t/c
m2で熱間鍛造し、気孔の割合が５％以下となるまで焼結
体22を緻密化する。これで一連の焼結鍛造工程が終了
し、鍛造後の黒皮材を自然冷却した後、仕上げ加工すれ
ば、所望の部品が得られる。The sintered body 22 taken out of the heating furnace 10 is immediately subjected to a surface pressure of 8 t / c.
Hot forging is performed at m 2 , and the sintered body 22 is densified until the ratio of pores becomes 5% or less. This completes a series of sintering and forging processes, and after the forged black scale material is naturally cooled and then finished, a desired part can be obtained.
上記方法により鍛造した黒皮材の試験片を用いて、疲
労試験を行った。その結果を次頁の第１表に示す。試験
方法は、第３図に示すように、全長L:100mm,大径部の直
径R:24mm,小径部の直径r:10mm,中央部の長さP:20mmの試
験片30と、比較のために、試験片30と同様の材料を用い
て予備成形体を形勢し、RXガス中で焼結させた後直ぐ加
熱炉から取り出して鍛造した試験片（以下、従来の試験
片という）とを用意し、両振り試験機を用いて、各試験
片の両端部を試験機に把持させて引張圧縮し、疲労強度
を測定した。また、試験片30および従来の試験片にショ
ットピーニング処理を行った後、同様の試験を行った。
その結果も併記する。なお、ショットピーニング処理
は、ターンブラスト機により粒径1.4mmのショット粒を
用いて約20分間行った。A fatigue test was performed using black scale material test pieces forged by the above method. The results are shown in Table 1 on the next page. As shown in FIG. 3, the test method was a test piece 30 having a total length L: 100 mm, a large diameter part R: 24 mm, a small diameter part r: 10 mm, and a central part length P: 20 mm. For this purpose, a preform was formed using the same material as the test piece 30, and after sintering in RX gas, the test piece was taken out of the heating furnace immediately after forging (hereinafter referred to as a conventional test piece). Using the swing tester, both ends of each test piece were gripped by the tester and subjected to tensile compression to measure the fatigue strength. The same test was performed after the shot peening treatment was performed on the test piece 30 and the conventional test piece.
The results are also shown. The shot peening treatment was performed for about 20 minutes using a shot grain having a particle diameter of 1.4 mm by a turn blast machine.
上記から明らかなように、本発明方法により製造した
試験片30は、従来方法により製造した従来の試験片に比
較して疲労強度が高い。特に、ショットピーニング処理
後は、試験片30と従来の試験片との強度差が1.5kg/mm2
から5kg/mm2へと大きくなっており、ショットピーニン
グ処理により試験片30の強度がさらに増すことが判明し
た。これは、ショットピーニング処理が試験片30のごく
表層部の微細な切欠に対しては顕著な効果が得られるの
に対して、0.5mmというような比較的内部まで存在する
欠陥に対しては十分な効果がないためと考えられる。 As is clear from the above, the test piece 30 manufactured by the method of the present invention has higher fatigue strength than the conventional test piece manufactured by the conventional method. In particular, after the shot peening treatment, the difference in strength between the test piece 30 and the conventional test piece was 1.5 kg / mm 2
From 5 to 5 kg / mm 2 , and it was found that the strength of the test piece 30 was further increased by the shot peening treatment. This is because the shot peening process has a remarkable effect on minute notches in the very surface layer of the test piece 30, whereas it has a sufficient effect on defects relatively deep inside such as 0.5 mm. It is considered that there is no significant effect.
上記試験片30の静的引張破断面を走査電子顕微鏡で観
察した。その写真を第４図に示す。写真から明らかなよ
うに、試験片30の表面から約0.1mm以下のごく表層部に
未結合部（例えば直線k,mの交点の位置に見られる）が
残っているのみであり、それより内部には未結合部は見
当たらない。試験片30の内部の酸化が、従来に比較して
大幅に抑制されているためであると考えられる。The static tensile fracture surface of the test piece 30 was observed with a scanning electron microscope. The photograph is shown in FIG. As is clear from the photograph, only the unbonded portion (for example, found at the position of the intersection of the straight lines k and m) remains on the very surface layer of about 0.1 mm or less from the surface of the test piece 30. Has no unbonded parts. It is considered that this is because the oxidation inside the test piece 30 is significantly suppressed as compared with the related art.
第１図は本発明の一実施例である焼結鍛造方法に用いら
れる加熱炉を概念的に示す説明図である。第２図は上記
方法により形成される焼結体の一部を概念的に示す正面
断面図であり、第３図は上記方法により形成される試験
片を示す正面図である。第４図は上記方法により形成さ
れる焼結体の金属組織の顕微鏡写真であり、第５図は従
来の焼結鍛造方法により形成される焼結体の一部を概念
的に示す正面断面図である。第６図は従来の焼結体の金
属組織の顕微鏡写真であり、第７図ないし第９図は同じ
く従来の焼結体の金属組織の顕微鏡写真である。 10:加熱炉、22:焼結体 24:開気孔、30:試験片FIG. 1 is an explanatory view conceptually showing a heating furnace used in a sintering forging method according to one embodiment of the present invention. FIG. 2 is a front sectional view conceptually showing a part of the sintered body formed by the above method, and FIG. 3 is a front view showing a test piece formed by the above method. FIG. 4 is a micrograph of the metal structure of the sintered body formed by the above method, and FIG. 5 is a front sectional view conceptually showing a part of the sintered body formed by the conventional sintering forging method. It is. FIG. 6 is a micrograph of the metal structure of the conventional sintered body, and FIGS. 7 to 9 are micrographs of the metal structure of the conventional sintered body. 10: heating furnace, 22: sintered body 24: open pores, 30: test piece
Claims (1)
その予備成形体を加熱炉内で加熱して焼結体とした後、
その焼結体を鍛造して製品とする焼結鍛造方法におい
て、 前記焼結体の前記加熱炉からの取出しに際して、その焼
結体の周囲を真空雰囲気とすることによりその焼結体の
開気孔内を脱気し、その脱気された開気孔内に不発火性
ガスを充満させた後、焼結体を大気中へ取り出すことを
特徴とする焼結鍛造方法。1. A preform is formed by molding a raw material powder,
After heating the preform in a heating furnace to form a sintered body,
In a sintering forging method of forging the sintered body into a product, when taking out the sintered body from the heating furnace, the surroundings of the sintered body are set to a vacuum atmosphere to open the pores of the sintered body. A sintering forging method, wherein the inside is degassed, the degassed open pores are filled with a non-ignitable gas, and the sintered body is taken out to the atmosphere.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2122020A JP2737358B2 (en) | 1990-05-11 | 1990-05-11 | Sintering forging method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2122020A JP2737358B2 (en) | 1990-05-11 | 1990-05-11 | Sintering forging method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0417602A JPH0417602A (en) | 1992-01-22 |
| JP2737358B2 true JP2737358B2 (en) | 1998-04-08 |
Family
ID=14825596
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2122020A Expired - Fee Related JP2737358B2 (en) | 1990-05-11 | 1990-05-11 | Sintering forging method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2737358B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6014954B2 (en) * | 2012-06-04 | 2016-10-26 | 住友電工焼結合金株式会社 | Method for manufacturing sintered parts |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63190102A (en) * | 1987-02-02 | 1988-08-05 | Showa Denko Kk | Production of sintered and forged product of aluminum alloy |
-
1990
- 1990-05-11 JP JP2122020A patent/JP2737358B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0417602A (en) | 1992-01-22 |
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