JPH0115578B2

JPH0115578B2 -

Info

Publication number: JPH0115578B2
Application number: JP57126263A
Authority: JP
Inventors: Masayuki Iijima; Hidetoshi Akutsu; Kazuyuki Hoshino
Original assignee: Mitsubishi Metal Corp
Current assignee: Mitsubishi Metal Corp
Priority date: 1982-07-20
Filing date: 1982-07-20
Publication date: 1989-03-17
Also published as: JPS5916951A

Description

[Detailed description of the invention]

この発明は、すぐれた耐摩耗性を有し、特に苛
酷な摩耗条件である土砂摩耗や泥砂摩耗にさらさ
れる建設機械や鉱山機械の構造部材の製造に用い
るのに適したFe基焼結材料に関するものである。従来、この種の構造部材の製造には、クロム鋳
鉄やCr―Mo鋳鉄、さらにCr―Mo―Ｖ鋳鉄など
の白鉄系鋳鉄が使用されているが、これらの白鉄
系鋳鉄は、いずれも硬くて脆い炭化物が針状，板
状，あるいは網目状に析出した組織をもつもので
あるため、高硬度をもつものの強度および靭性が
著しく劣り、この結果実用に際しては比較的短か
い使用寿命しか示さず、また鋳造性もきわめて悪
く、巣の発生の著しいものであるため、安定的量
産性に欠けるという問題点があるものである。一方、これら構造部材の製造に際して、摩耗部
分に耐摩耗性のすぐれた炭化タングステン基超硬
合金や炭化チタン基サーメツトなどのチツプをろ
う付けする試みもなされているが、これらの材料
は高価であるばかりでなく、耐衝撃性などに問題
があり、さらにろう付け強度にも問題があつて十
分満足する信頼性が得られていないのが現状であ
る。そこで、本発明者等は、上述のような観点か
ら、すぐれた耐摩耗性を有し、特に土砂摩耗や泥
砂摩耗などの苛酷な摩耗条件にさらされる構造部
材の製造に適した材料を安定的量産性の可能な粉
末冶金法を用いて、コスト安く得べく研究を行な
つた結果、焼結材料を、重量％で、Cr：４〜25
％、Ｃ：1.5〜５％、Mo：0.1〜20％、Mn：0.1〜
10％を含有し、残りがFeと不可避不純物からな
る組成を有すると共に、主としてマルテンサイト
からなる素地にビツカース硬さで1200以上を有す
る炭化物が面積比で15％以上分散した組織を有
し、かつ前記炭化物のうち、炭化物全体に対する
面積比で10％以上が平均粒径：5μm以上を有する
炭化物で占められ、さらに92％以上の密度比を有
するもので構成すると、前記Fe基焼結材料にお
いては、上記炭化物によつてすぐれた耐摩耗性が
確保され、また上記マルテンサイト素地および密
度比によつて高強度および高靭性が確保されるよ
うになり、したがつて、このFe基焼結材料を上
記のような苛酷な摩耗環境下で使用した場合、著
しく長期に亘つてすぐれた性能を発揮するように
なるという知見を得たのである。この発明は、上記知見にもとづいてなされたも
のであつて、成分組成，炭化物の面積比，および
密度比を上記の通りに限定した理由を以下に説明
する。Ａ成分組成 (a) ＣＣ成分には、素地に固溶して、これを強化する
と共に、Cr，さらにMoと結合してビツカース硬
さで1200以上を有する硬い炭化物を形成して材料
の耐摩耗性を向上させる作用があるが、その含有
量が1.5％未満では、素地中に分散析出する炭化
物の量が少なすぎて、全体面積比で15％未満とな
ると共に、5μm以上の平均粒径をもつた炭化物の
量も炭化物全体に対する面積比で10％未満となつ
てしまい、土砂などによる摩耗が著しく、所望の
すぐれた耐摩耗性を確保することができず、さら
に素地を構成するマルテンサイトの割合も全体面
積比で70％未満となつてしまつて所望の強度およ
び耐摩耗性を確保することができず、一方５％を
越えて含有させると、材料が極端に脆化するよう
になつて所望の強度および靭性を確保するのが困
難になることから、その含有量を1.5〜５％と定
めた。 (b) Cr Cr成分には、素地に固溶して、これを強化す
ると共に、上記のようにＣと結合して高強度を有
するCr炭化物を形成し、かつMoと複炭化物を形
成し、もつて材料の耐摩耗性を向上させる作用が
あるが、その含有量が４％未満では、Ｃ成分の場
合と同様に所定の炭化物を所定の量、分散析出さ
せることができず、一方25％を越えて含有させる
と、Ｃ成分の場合と同様に材料が脆化するように
なることから、その含有量を４〜25％と定めた。 (c) Mo Mo成分には、素地に固溶して、これを強化す
るほか、Ｃと結合してきわめて硬い炭化物および
複炭化物を形成し、もつて材料の耐摩耗性を一段
と向上させる作用があるが、その含有量が0.1％
未満では所望の耐摩耗性向上効果が得られず、一
方20％を越えて含有させると材料に脆化傾向が現
われるようになることから、その含有量を0.1〜
20％と定めた。 (d) Mn Mn成分には、素地に固溶して、これを一段と
強化し、かつ材料の靭性を著しく向上させる作用
があるが、その含有量が0.1％未満では前記作用
に所望の向上効果が得られず、一方10％を越えて
含有させてもより一層の向上効果は現われないこ
とから、経済性をも考慮して、その含有量を0.1
〜10％と定めた。Ｂ密度比密度比が92％未満では、空孔多過に原因する剥
離摩耗が生ずるようになるばかりでなく、所望の
高強度を確保することが困難となることから、密
度比の下限値を92％と定めた。つぎに、この発明のFe基焼結材料を実施例に
より具体的に説明する。実施例原料粉末として、粒度−100meshのFe粉末、
いずれも粒度−100meshを有し、かつCr含有量が
それぞれ５％、13％、25％、35％、および65％の
５種類のFe―Cr合金粉末、同−100meshのカー
ボン粉末、平均粒径：3μmを有するMo粉末、粒
度：−100meshのFe―Mn合金（Mn：75％含有） The present invention relates to an Fe-based sintered material that has excellent wear resistance and is suitable for use in manufacturing structural members of construction machines and mining machines that are exposed to particularly severe wear conditions such as earth and sand abrasion and mud and sand abrasion. It is something. Traditionally, white iron cast irons such as chromium cast iron, Cr-Mo cast iron, and Cr-Mo-V cast iron have been used to manufacture this type of structural member. It has a structure in which hard and brittle carbides are precipitated in the form of needles, plates, or networks, so although it has high hardness, its strength and toughness are significantly inferior, and as a result, it has a relatively short service life in practical use. In addition, the castability is extremely poor and the formation of cavities is significant, so there is a problem that stable mass production is lacking. On the other hand, when manufacturing these structural members, attempts have been made to braze chips such as tungsten carbide-based cemented carbide or titanium carbide-based cermet, which have excellent wear resistance, to the worn parts, but these materials are expensive. In addition, there are problems with impact resistance, etc., and there are also problems with brazing strength, making it difficult to achieve sufficient reliability. Therefore, from the above-mentioned viewpoint, the present inventors have developed a stable material that has excellent wear resistance and is suitable for manufacturing structural members that are particularly exposed to severe wear conditions such as dirt abrasion and muddy sand abrasion. As a result of conducting research to obtain a low-cost product using a powder metallurgy method that can be mass-produced, we found that the sintered material had a Cr content of 4 to 25% by weight.
%, C: 1.5~5%, Mo: 0.1~20%, Mn: 0.1~
10%, with the remainder consisting of Fe and unavoidable impurities, and has a structure in which carbides with a Vickers hardness of 1200 or more are dispersed in a matrix mainly consisting of martensite in an area ratio of 15% or more, and In the Fe-based sintered material, if the carbide is composed of carbide having an average particle size of 5 μm or more and a density ratio of 92% or more, 10% or more of the carbide in terms of area ratio to the whole carbide is The carbide ensures excellent wear resistance, and the martensitic matrix and density ratio ensure high strength and toughness. They have found that when used under the severe abrasive environment described above, they exhibit excellent performance over an extremely long period of time. This invention has been made based on the above findings, and the reason why the component composition, the area ratio of carbides, and the density ratio are limited as described above will be explained below. A Component composition (a) C The C component is solid dissolved in the base material to strengthen it, and also combines with Cr and Mo to form a hard carbide with a Vickers hardness of 1200 or more, increasing the durability of the material. It has the effect of improving wear resistance, but if its content is less than 1.5%, the amount of carbide dispersed and precipitated in the matrix will be too small, resulting in less than 15% of the total area ratio, and the average grain size of 5 μm or more The amount of carbides with a hard surface area is less than 10% of the total carbide, and the abrasion caused by earth and sand is significant, making it impossible to secure the desired excellent wear resistance. If the content exceeds 5%, the material becomes extremely brittle. Since it becomes difficult to secure the desired strength and toughness, the content was set at 1.5 to 5%. (b) Cr The Cr component is dissolved in solid solution in the base material to strengthen it, and as mentioned above, combines with C to form a Cr carbide having high strength, and forms a double carbide with Mo, It has the effect of improving the wear resistance of the material, but if its content is less than 4%, it will not be possible to disperse and precipitate the specified carbide in the specified amount, as in the case of the C component; If the content exceeds 4%, the material becomes brittle as in the case of the C component, so the content was set at 4 to 25%. (c) Mo The Mo component not only dissolves in the base material and strengthens it, but also combines with C to form extremely hard carbides and double carbides, thereby further improving the wear resistance of the material. Yes, but its content is 0.1%
If the content is less than 20%, the desired effect of improving wear resistance cannot be obtained, while if the content exceeds 20%, the material tends to become brittle.
It was set at 20%. (d) Mn The Mn component has the effect of forming a solid solution in the base material, further strengthening it, and significantly improving the toughness of the material, but if its content is less than 0.1%, the desired improvement effect on the above effect is not achieved. On the other hand, even if the content exceeds 10%, no further improvement effect will be obtained. Therefore, considering economic efficiency, the content should be reduced to 0.1%.
It was set at ~10%. B Density Ratio If the density ratio is less than 92%, not only will exfoliation wear caused by too many pores occur, but it will also be difficult to secure the desired high strength. It was set at 92%. Next, the Fe-based sintered material of the present invention will be specifically explained using Examples. Example As raw material powder, Fe powder with particle size -100mesh,
Five types of Fe-Cr alloy powders, each with a particle size of -100mesh and Cr content of 5%, 13%, 25%, 35%, and 65%, respectively, and carbon powder with -100mesh, average particle size : Mo powder with 3μm, particle size: -100mesh Fe-Mn alloy (Mn: 75% content)

【表】粉末を用意し、これら原料粉末をそれぞれ第１表
に示される配合組成に配合し、湿式ボールミルに
て混合し、乾燥した後、４〜6ton／cm²の圧力にて
圧粉体に成形し、ついでこの圧粉体を真空中、
1150〜1350℃の温度範囲内の所定温度で焼結し、
引続いて焼結後850〜1050℃の温度範囲内の所定
温度から油焼入れし、最終的に150〜250℃の温度
範囲内の所定温度で焼戻し処理を行なうことによ
つて、実質的に配合組成と同一の成分組成をもつ
た本発明焼結合金１〜14をそれぞれ製造した。つぎに、この結果得られた本発明焼結合金１〜
34について、密度比、炭化物面積比、平均粒径：
5μm以上を有する炭化物の炭化物全体に占める面
積比およびビツカース硬さを測定すると共に、共
づり形式で、粒度−30meshの土砂を25容量％含
有する泥水中、荷重：４Kg／cm²、回転速度：
180r.p.m.、試験時間：25時間の条件で摩耗試験
を行ない、その摩耗深さを測定した。これらの測
定結果を第１表に示した。また、第１表には比較
の目的で従来Cr鋳鉄（Ｃ：3.4％、Si：2.1％、
Mn：0.7％、Cr：0.9％含有）の同一条件による
摩耗試験結果も示した。第１表に示される結果から、本発明焼結合金１
〜34は、いずれも従来Cr鋳鉄に比して著しくす
ぐれた耐摩耗性を有し、かつ高強度、高硬度、お
よび高靭性をもつことが明らかである。上述のように、この発明の焼結材料は、すぐれ
た耐摩耗性を有し、かつ高強度および高靭性を有
するので、これらの特性が要求される分野での使
用は勿論のこと、特に土砂摩耗や泥砂摩耗などの
苛酷な摩耗環境にさらされる建設機械や鉱山機械
の構造部材として使用した場合にも著しく長期に
亘つてすぐれた性能を発揮するのである。[Table] Prepare powders, blend these raw material powders into the composition shown in Table 1, mix them in a wet ball mill, dry them, and then form them into a green compact under a pressure of 4 to 6 tons/cm ² . After molding, the green compact is placed in a vacuum.
Sintered at a predetermined temperature within the temperature range of 1150-1350℃,
Subsequently, after sintering, oil quenching is performed at a predetermined temperature within the temperature range of 850 to 1050°C, and finally tempering treatment is performed at a predetermined temperature within the temperature range of 150 to 250°C, thereby substantially compounding. Sintered alloys 1 to 14 of the present invention having the same composition as the composition were manufactured, respectively. Next, the resulting sintered alloys of the present invention 1-
Regarding 34, density ratio, carbide area ratio, average particle size:
The area ratio of carbides having a particle size of 5 μm or more to the whole carbide and the Vickers hardness were measured, and the test was carried out in muddy water containing 25% by volume of earth and sand with a particle size of -30mesh at a load of 4 Kg/cm ² and a rotation speed:
A wear test was conducted under the conditions of 180 rpm and test time: 25 hours, and the wear depth was measured. The results of these measurements are shown in Table 1. Table 1 also shows conventional Cr cast iron (C: 3.4%, Si: 2.1%,
The wear test results under the same conditions for Mn: 0.7%, Cr: 0.9%) are also shown. From the results shown in Table 1, the present invention sintered alloy 1
It is clear that all of No. 34 have significantly superior wear resistance compared to conventional Cr cast iron, and also have high strength, high hardness, and high toughness. As mentioned above, the sintered material of the present invention has excellent wear resistance, high strength, and high toughness, so it can be used not only in fields that require these properties, but also especially in soil and sand. Even when used as a structural member of construction machinery or mining machinery that is exposed to severe abrasion environments such as abrasion and muddy sand abrasion, it exhibits excellent performance over an extremely long period of time.

Claims

[Claims] 1 Cr: 4 to 25%, C: 1.5 to 5%, Mo: 0.1 to 20%, Mn: 0.1 to 10%. % by weight), and carbides with a Bitkers hardness of 1200 or more are present in the area ratio on a matrix mainly composed of martensite.
It has a dispersed composition of 15% or more, and of the carbide, 10% or more of the carbide has an average particle size of 5 μm or more in terms of area ratio to the whole carbide, and further has a density ratio of 92% or more. Fe-based sintered material with excellent wear resistance.