JPS5970747A - Free-cutting alloy steel for machine structure use - Google Patents

Abstract

PURPOSE:To prevent deterioration in the toughness of the resulting titled alloy steel, by adding a specified amount of Sb to a steel composition contg. a restricted amount of S as well as C, Si, Mn, Cr and Mo. CONSTITUTION:This free-cutting machine structural alloy steel has a composition consisting of, by weight, 0.20-0.50% C, 0.15-1.50% Si, 0.30-1.50% Mn, 0.20-1.50% Cr, 0.05-0.50% Mo, 0.005-0.030% S, 0.01-0.05% Sb and the balance essentially Fe.

Description

【発明の詳細な説明】[Detailed description of the invention]

この発明は快削性機械構造用合金鋼に関するものである
。 一般に構造用強靭鋼は、焼入れ焼もどしによって比軟的
容易に高い強度と靭性を発揮し、またそれよりも炭素含
有量がやや低いいわゆるはだ焼鋼は・浸炭′窒化などの
処理を加えて、何れも建設機材や電気機器もしくは、自
動車、原動イ幾その他機械器具類の部品用材料として使
用されている。 最近の経済状勢から、この種の機械構造用合金鋼による
部品の製作上、加工コストが安価であることが望まれ、
なかでも切削加工費節減のため良好な被切削性がきびし
く要求される。 それというのは、上記のような部品の工作例えば穴あけ
加工やねじ切り加工に際して、切削速度を高くすると工
具寿命が短かくなり、生産性に多大の影響をおよぼすか
らである。 一般に鋼材の被切削性を改嵜する試みは古くからＳｉの
、１胃加、比較的最近に至ってＯａをはじめＴｉ＋　Ｔ
ｅ　＋　ｐｂなどの添加による開発成果に見るべきもの
があり、いわゆる快削鋼の種類も増加し、上渇の強靭＼
−やはだ貌も含めた研究努力が傾けられつつあるが、Ｓ
快削鋼以来の難点であった高温ぜい性のため、熱間加工
性の低下が余儀なくされる問題点が未だ完全には解決さ
れ得す、かくして安価で安定した品質の機械構造用合金
鋼の供給を阻む原因をなしているのが現状である。 発明者らは、この点について種々検討した結果（３，Ｓ
土＋　Ｍｎ　、　ＯｒおよびＮＯを含有し、Ｓ量に制限
を加えたｍ組成において特定量のｓｂを含有させること
により、靭性に関するネックを有利に解決して高い波切
剛性を確保し得ることを究明した。 従ってこの発ＦｊＪＪは、とくに機械（１“４造Ｊ、１
１１合金鋼につき、その靭性劣化のうれいなしにｔ皮切
削性の有利な」９強を目的とするものである。 コ（７３発１ｆｆｌ　６：ｆ、ａ　：　（１，２０ＮＯ
，５０１１５６４（以下単ニ％　テ示ｔ　）　、　Ｓｉ
　：　０．１５〜１．１　’１ｇ、Ｍｎ　：　ｏ、ｓ。 〜１４０　％　、　Ｏｒ　：　０．２０〜１．ＦｌＯ％
、Ｎｏ　：　ｏ、Ｏ５〜０．５０係を含有し、ｓ　：　
０．００５〜ｏ、ｏａｏ憾であってざらにＳｂ　：　（
＋、（１１ＮＯ，ＯＦｉ係を含んで残部は実質的にＦｅ
の組成とする成分調帯を、上記従来技術上の課題につい
てとくに有効な解決手段とするものである。 まずこの発明において鋼の化学組成を限定する理由を説
明する。 （３：　０．２０〜＋１．ｌｉｏ　Ｉ Ｃは、鋼の強度上昇に有効な成分であるが、０．２０係
未満では、強度、焼入性がｊ面保されず−／ｉ、　０．
５０係をこえると、熱処理時に焼割れが発生しゃすく、
また焼戻し脆性も太きく、シかも被切削性の劣化を半う
ので、＋１　、２０〜０．５０　％の範囲に限定した。 Ｓｉ　：　０．１５〜１．５０係 Ｓｉは、鋼の脱酸と強度上昇のために０．１５　’１以
上を必”逐とするが、一方１．５０　％をこえると靭性
の劣化が著しく、かつ被切削性も低下するので、０．１
５〜１．５（＋優の範囲に限定したＯＭｎ　：　ｆｌ、
３０　Ｎ１．５０　％Ｎｎは、ＯｒおよびＭｏとともに
焼入性増大に関して１、ｖに効果的でＸ−の強度ならび
に靭性を高めるため（）。；（０％以上を必要とするが
、一方１．５０４をこえると熱処理時に焼割れか発生し
やすくなるので、０゜３０〜１．５０　％の範囲に限定
した。 Ｇｒ　７０．２０　Ｎ１．Ｆｌ（１４ ０ｒ　Ｇま焼入性および強度上昇に有効な点で０．２０
係以上の含有を要するが、一方１゜５０幅？こえて多ｉ
１！−に含有させると靭性の劣化をきたすので０．２０
〜１．５０係の範囲に限定した。 ＭＯ：０゜［ＩＦ１〜（１，５０％ Ｎｏもまた強バｒ上昇に？ａ量でとくに、ｑ効な成分で
あって、（１，０５４以上の含有を必要と１′る力弧−
１Ｉモ抽なため、せいぜい０゜５０　％までσ）範囲で
な（／島と・！ａ４　ＡＡ’　Ｉ：ｌＴｉ格への影’ｓ
ｉが著しくなる（１）−ｃ、１ｌＪ５〜（１、５０係の
範囲とするＯ ３　　：　　０．＋１０５〜０　、　（１８０係Ｓは被
切削性向上に有効なことは古くから仰られているとおり
であるが、製造時とくＧこ支障なく操業できるのは、０
．０１１１；　％が限度であり、一方０．０８０チをこ
えて過量になると、熱間加工性を低下させ、この発明の
目的に反するσ）で０　、１１０５〜０．０３０４の範
囲が許容される。 Ｓｔ）　：　０．（１１〜０．０５　％Ｓｌ）は、後述
する第１図の実験結果に基づく新たな知見の下に、被切
削性向上に有効なｄ与をもたらし、ここにThis invention relates to a free-cutting alloy steel for machine structures. In general, strong structural steels can easily exhibit high strength and toughness through quenching and tempering, while so-called case hardened steels, which have a slightly lower carbon content, can be made by undergoing treatments such as carburizing and nitriding. Both are used as materials for construction equipment, electrical equipment, and parts for automobiles, motor vehicles, and other mechanical equipment. Due to the recent economic situation, it is desired that the processing cost is low when manufacturing parts using this type of machine structural alloy steel.
Above all, good machinability is strictly required to reduce cutting costs. This is because when machining the above-mentioned parts, such as drilling or thread cutting, increasing the cutting speed shortens tool life, which has a great effect on productivity. In general, attempts to improve the machinability of steel materials have been made since ancient times using Si, monomer, and relatively recently, Oa and Ti+T.
There are noteworthy development results due to the addition of e + PB, etc., and the number of types of so-called free-cutting steels has increased, making it extremely tough.
-Although research efforts are being made that include bare-faced appearance,
The problem of high-temperature brittleness, which has been a problem since free-cutting steels, resulting in a reduction in hot workability has not yet been completely resolved, and thus an inexpensive and stable quality alloy steel for machine structures has been developed. The current situation is that this is hindering the supply of As a result of various studies on this point (3, S
It was discovered that by including a specific amount of sb in the m composition containing soil + Mn, Or, and NO, and with a limit on the amount of sulfur, it was possible to advantageously solve the problem regarding toughness and ensure high wave cutting stiffness. did. Therefore, this origin FjJJ is especially suitable for machines (1"4 construction J, 1
11 alloy steel, the objective is to achieve a strength of 9 or above, which has advantageous skin machinability without deterioration of toughness. Ko (73 shots 1ffl 6: f, a: (1,20NO
, 5011564 (hereinafter referred to as %), Si
: 0.15-1.1'1g, Mn: o, s. ~140%, Or: 0.20~1. FlO%
, No: o, contains O5~0.50 ratio, s:
0.005~o, oao unfortunately Sb: (
+, (including 11NO and OFi, the rest is substantially Fe)
The component adjustment band having the composition is a particularly effective solution to the above-mentioned problems in the prior art. First, the reason for limiting the chemical composition of steel in this invention will be explained. (3: 0.20 to +1.io I C is an effective component for increasing the strength of steel, but if it is less than 0.20, the strength and hardenability cannot be maintained on the j-plane -/i, 0.
If it exceeds 50%, quench cracking will occur during heat treatment.
In addition, the tempering brittleness is large, and the deterioration of machinability is reduced by half, so it is limited to a range of +1.20 to 0.50%. Si: 0.15% to 1.50% Si must be at least 0.15% to deoxidize the steel and increase its strength, but on the other hand, if it exceeds 1.50%, the toughness will deteriorate significantly. , and the machinability also decreases, so 0.1
OMn limited to the range of 5 to 1.5 (+ excellent: fl,
30N1.50%Nn is effective to 1,v in increasing hardenability together with Or and Mo to increase the strength and toughness of X- (). (Although 0% or more is required, on the other hand, if it exceeds 1.504, quench cracking is likely to occur during heat treatment, so it was limited to a range of 0°30 to 1.50%.Gr 70.20 N1.Fl (140rG) 0.20 in terms of effectiveness in increasing hardenability and strength
However, on the other hand, 1°50 width? Go beyond
1! -0.20 as it will cause deterioration of toughness if it is contained in
It was limited to a range of 1.50 to 1.50. MO: 0゜[IF1~(1,50% No is also a component that has a strong q-effect on increasing the bar, especially in the amount of a.
Since it is a 1I mo lottery, it is within the range of σ to 0°50% at most (/Shimato・!a4 AA' I:lTi case's shadow's
i becomes significant. This is true, but during manufacturing, G can be operated without any trouble at 0.
．． 0111; % is the limit; on the other hand, if the amount exceeds 0.080, the hot workability will be reduced, which is contrary to the purpose of this invention. . St): 0. (11 to 0.05% Sl) brings effective d to improve machinability, based on new knowledge based on the experimental results shown in Figure 1, which will be described later.

【）。ｆ１１
％以上で含有するを要する力；、一方（＋、（１５％を
こえて過用゛に含有させると、靭性を劣化させることと
なるので０．０１〜０．＋１５４の範囲に限定した。 次にこの発ＤＩ（の実施例について説明するＯ眞空誘香
炉によって衣１に示す取分組成に溶製した５トン情塊を
通常の熱間圧延工程によって、ブルームにし、ついで１
８０美朋φ九棒に仕上げ、被切削性および靭性の指標と
してシャルピー衝撃値を調存した。 供試；１０〜Ａ８＋Ａ５＋６は発明鋼であり−Ａ４およ
びＡ７は比較鋼である。 各供試鋼の被切削性試験として、供試＃Ａ１〜應７につ
いてドリル穴あけを、供試鋼Ａ］〜Ａ４について確削を
行ない、表２にその試験結果を示す。なおこの被剛性の
試験は焼入れのあと焼戻し温度を変え、表２に併記の硬
さに揃えて行った０表　２ 評価法として前者は高速度１ｆ＠ドリルを用い、送りｏ
　、　ｓ　】ｒｓ　＊１Ｖｒｅｖ　、切削速度２　ｆｌ
　ｍ／ｍｉｎで１５φ×８０ｍｍの−・Ｊ化を行ないド
リルが損傷する￥１５での全切削長さ、（々渚Ｏま超硬
工具のフランク摩耗幅ＶＢ　”−０，２朋に主る工具寿
皓（分）で行った。 表２から明らかなようにこの発明に（ＩＥう成分組成範
囲内で著しくずぐれた被削性がもたらされる・次にこの
発明に従い、　Ｑ　：　０．２５〜（１、２ｉｌ係、ｓ
ｌ：　０．２Ｆ１〜０．０１５、Ｍｎ　：　１．０（１
〜１．１＋２４、ｃｒ：１．２０〜１．２２　％、ＭＯ
：　０．２６〜０．３０％ニオイテＰ　：　０．０１２
〜０．０１５４％Ｓ　：　０．０２２〜０．（１２１１
％を含みかつ０．０６係以下の含有量となるＳｂの添加
をした供試材につき、被切削性に及ぼすｓｂの影響を調
査検討した結果、第１図に示すように（１、（１５壬を
こえるとシャルピー衝撃値が急激に低下し、靭性の劣化
現象をきたすことが判明し、またこのｓｂ含有ｉの影響
は、すでにのべた成分範囲がらの逸脱がない限りにおい
てほぼ同様の効果がイｉ４られた。 以」二のべたように、この発明ではｓｂ含有量の調整に
よってａｌ性の劣化を伴うことなしに、有利に被切削性
の向上をもたらすことができた。 この発１？Ｊｌの機械＋ｉ／／造用合金＠は、通常の溶
解、造塊、熱間圧延による製造過程ζまもちろん、とく
に転炉ｆＩＶ錬を経た連Ｐ、ＩＢ　、柘造過程を経で、
同様に熱間圧延に（ｊ９　Ｌ、（乍４＆Ｉ　−線材その
細板状体などして部品加工ＩＯ材料に供し、その＆１−
品工作を終えたあと、焼入れ、Ｂｉｔ戻しの熱処理を、
また場合によってはこのような熱処理に先立って浸炭％
窒化など、の処理をｈ屯し、必四強度を靭性にあわせ発
揮されイする。 以上のとおり、この発明によれば靭性の阻害なくして被
切削性の改−得を「保できるので機械構造用合金鋼の各
種の使途に安価で、しかも良質な上、ｔノ１削加エコス
トの嵩むことのない部品を提供できる０ ４、図面の１７ｉ’ｊ　１（４−な説明第１１３２１は
、シャルピー衝撃値におよぼすｓｂ含有量の影・１牙を
示すグラフである。[). f11
On the other hand, if the content exceeds 15%, the toughness will deteriorate, so it is limited to a range of 0.01 to 0.+154.Next To explain an example of this production DI, 5 tons of ingots melted using a manku incense burner to the composition shown in 1 were made into bloom by a normal hot rolling process, and then 1
A bar with a diameter of 9 mm and 80 mm was finished, and the Charpy impact value was measured as an index of machinability and toughness. Tests: 10 to A8+A5+6 are invention steels, and -A4 and A7 are comparative steels. As a machinability test for each sample steel, drilling was performed for samples #A1 to #7, and cutting was performed for sample steels A] to A4, and the test results are shown in Table 2. In addition, this stiffness test was conducted by changing the tempering temperature after quenching and adjusting the hardness to the hardness listed in Table 2.
, s ]rs *1Vrev, cutting speed 2 fl
The total cutting length at ¥15 when the drill is damaged by cutting 15φ x 80mm at m/min. As is clear from Table 2, this invention provides significantly superior machinability within the component composition range (IE). Next, according to this invention, Q: 0.25 ~ (1, 2il staff, s
l: 0.2F1~0.015, Mn: 1.0(1
~1.1+24, cr:1.20~1.22%, MO
: 0.26-0.30%NioiteP: 0.012
~0.0154%S: 0.022~0. (1211
As a result of investigating and examining the influence of Sb on machinability for the test materials containing Sb with a content of 0.06% or less, as shown in Figure 1, (1, (15 It was found that the Charpy impact value sharply decreases when the temperature exceeds the limit, causing a deterioration of toughness, and the effect of sb content is almost the same as long as there is no deviation from the component range already mentioned. As mentioned above, in this invention, by adjusting the sb content, it was possible to advantageously improve the machinability without deteriorating the alkalinity. Jl's machine +i//building alloy @ is produced through the normal manufacturing process of melting, ingot-forming, and hot rolling.
In the same way, hot rolling (j9 L, (乍4&I-wire rod) is made into a thin plate-like body, etc., and used as part processing IO material, and the &1-
After finishing the work, heat treatment of hardening and bit resetting is carried out.
In some cases, prior to such heat treatment, carburization%
It undergoes many treatments such as nitriding to ensure strength and toughness. As described above, according to the present invention, it is possible to maintain improved machinability without impairing toughness, making it inexpensive and of high quality for various uses of alloy steel for machine structures, and with 100% machining cost. Figure 11321 is a graph showing the influence of the sb content on the Charpy impact value.

Claims (1)

【特許請求の範囲】[Claims] Ｌ　　Ｃｉ　：　０．２０〜０．５０重量％−Ｓｉ　７
０．１５〜１．５０ｉ’ｌｔ量％、Ｍｎ　：　０．；（
０〜１．５０重ｈｔ係重量ｒ　：　０．２０〜１．５０
重ｉ［、Ｍｏ　７０．０５〜０．５０ｉ量％を含有し、
Ｓ　Ｆ　０．Ｏ１２〜０．（１３０爪鷺係であって％さ
らにＳｂ　：　０．０１〜０．０５重量帯幅含んで残部
は実質的にＦｅの組成になることを特徴とする快削性機
械ＩＴ′Ｉｙ造用合金鋼。L Ci: 0.20-0.50% by weight-Si7
0.15-1.50 i'lt amount%, Mn: 0. ;(
0-1.50 weight ht weight r: 0.20-1.50
Contains 70.05 to 0.50 i weight% of
S F 0. O12~0. (130% Sb: 0.01 to 0.05 including the weight band width and the balance being substantially Fe for free-cutting machine IT'Iy manufacturing alloy steel) .