JPH0765140B2 - Case hardening steel for cold forging - Google Patents
Case hardening steel for cold forgingInfo
- Publication number
- JPH0765140B2 JPH0765140B2 JP61249144A JP24914486A JPH0765140B2 JP H0765140 B2 JPH0765140 B2 JP H0765140B2 JP 61249144 A JP61249144 A JP 61249144A JP 24914486 A JP24914486 A JP 24914486A JP H0765140 B2 JPH0765140 B2 JP H0765140B2
- Authority
- JP
- Japan
- Prior art keywords
- cold forging
- cold
- case
- crystal grains
- forging
- 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 - Lifetime
Links
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は肌焼鋼に係り、特に冷間鍛造用素材として好適
な肌焼鋼に関するものである。TECHNICAL FIELD The present invention relates to case hardening steel, and more particularly to case hardening steel suitable as a material for cold forging.
（従来の技術） 自動車、各種機械の動力伝達用部品等には、その用途上
必要とする機械的性質を得るために肌焼鋼が広く用いら
れている。これは、成形加工された前記部品に浸炭或い
は浸炭窒化等の表面硬化処理を施して、表面の強度、耐
摩耗性及び耐ピッチング性と芯部の強度及び靭性向上に
よって所要特性を得るためである。(Prior Art) Case hardening steel is widely used for power transmission parts of automobiles and various machines in order to obtain mechanical properties required for its application. This is because the molded part is subjected to a surface hardening treatment such as carburizing or carbonitriding to obtain the required characteristics by improving the surface strength, wear resistance and pitting resistance and the strength and toughness of the core. .
ところで、前記部品は肌焼鋼を加工して製造されるが、
その代表的な加工法としては、熱間鍛造、冷間鍛造が一
般に知られている。熱間鍛造は成形荷重が小さく、また
変形能が優れているが、スケールの発生、脱炭及び仕上
がり精度に問題があり、一方、冷間鍛造には、成形荷重
が大きく、変形能が劣っているという問題がある。By the way, the parts are manufactured by processing case hardening steel,
Hot forging and cold forging are generally known as typical processing methods. Although hot forging has a small forming load and excellent deformability, it has problems with scale generation, decarburization, and finish accuracy.On the other hand, cold forging has a large forming load and poor deformability. There is a problem that
後者の冷間鍛造においては、圧延材又は焼ならし材をそ
のまま冷間鍛造すると、成形荷重が大きく、また変形能
が低いという問題があるため、通常、炭化物を球状化さ
せて硬さを低下させる球状化焼なまし処理を施した後、
冷間鍛造を行なうが、その後の浸炭処理において結晶粒
が粗大化し易いという問題がある。In the latter cold forging, when cold forging a rolled material or normalizing material as it is, there is a problem that the forming load is large and the deformability is low. After spheroidizing annealing to
Although cold forging is performed, there is a problem that crystal grains are likely to coarsen in the subsequent carburizing treatment.
このように結晶粒が粗大化すると、部品の機械的性質、
特に靭性や疲労強度が劣化し、また、結晶粒が部分的に
粗大化した混粒或いは異常成長が生じると前記問題に重
畳して熱処理歪が大きくなるという問題も発生する。こ
のため、浸炭処理後の結晶粒はNo.7よりも細粒にするこ
とが好ましいと云われている。When the crystal grains become coarse in this way, the mechanical properties of the parts,
In particular, if the toughness and fatigue strength are deteriorated, and if mixed grains in which the crystal grains are partially coarsened or abnormal growth occurs, there arises a problem that heat treatment strain increases in addition to the above problem. For this reason, it is said that it is preferable to make the crystal grains after the carburizing treatment finer than No. 7.
（発明の目的） 本発明は、上記従来技術の問題点を解決するためになさ
れたものであって、冷間鍛造による加工法において冷間
鍛造性に優れ、かつ、鍛造部品の表面硬化処理による結
晶粒の粗大化を効果的に防止でき、必要に応じて更に強
度、靭性、被削性等も向上し得る冷間鍛造用肌焼鋼を提
供することを目的とするものである。(Object of the Invention) The present invention has been made in order to solve the problems of the above-mentioned conventional techniques, and is excellent in cold forgeability in a processing method by cold forging, and by surface hardening treatment of a forged part. An object of the present invention is to provide a case-hardening steel for cold forging, which can effectively prevent coarsening of crystal grains and can further improve strength, toughness, machinability, etc., if necessary.
（発明の構成） 上記目的を達成するため、本発明者は、従来の肌焼鋼を
化学成分面から再検討を加え、結晶粒の粗大化をもたら
す原因について分析し、その対策を見出すべく鋭意研究
を重ねた結果、特に適量のNbの添加とＮ量の規制によっ
て結晶粒の粗大化を防止できるとの知見を得、更に詳細
に化学成分を検討し、ここに本発明をなしたものであ
る。(Structure of the Invention) In order to achieve the above object, the present inventor reexamines the conventional case-hardening steel from the aspect of chemical composition, analyzes the cause of coarsening of the crystal grains, and is keen to find a countermeasure. As a result of repeated research, it was found that the coarsening of crystal grains can be prevented by the addition of an appropriate amount of Nb and the regulation of the amount of N. The chemical composition was studied in more detail, and the present invention was made here. is there.
すなわち、本発明は、C:0.10〜0.25％、Si≦0.15％、Mn
≦0.6％、Ti≦0.05％、B:0.0005〜0.0050％、solAl:0.0
15〜0.050％、Ｎ≦0.008％及びNb:0.01〜0.20％を含
み、更に必要に応じてCr≦1.5％、Mo≦0.5％及びNi≦３
％のうちの１種又は２種以上を含み、残余が実質的にFe
よりなることを特徴とする冷間鍛造性と冷間鍛造後の表
面硬化処理時の耐結晶粒粗大化性に優れた冷間鍛造用肌
焼鋼を要旨とするものである。That is, the present invention, C: 0.10 ~ 0.25%, Si ≤ 0.15%, Mn
≦ 0.6%, Ti ≦ 0.05%, B: 0.0005 to 0.0050%, solAl: 0.0
15 to 0.050%, N ≦ 0.008% and Nb: 0.01 to 0.20%, and if necessary Cr ≦ 1.5%, Mo ≦ 0.5% and Ni ≦ 3
% Of 1% or more, and the balance is substantially Fe.
The gist of the case-hardening steel for cold forging is excellent in cold forgeability and resistance to coarsening of crystal grains during surface hardening treatment after cold forging.
以下に本発明を実施例に基づいて詳細に説明する。The present invention will be described in detail below based on examples.
まず、本発明の肌焼鋼における化学成分の限定理由を説
明する。First, the reasons for limiting the chemical components in the case-hardening steel of the present invention will be described.
Ｃは部品の芯部強度を確保するために0.10％以上必要で
あるが、多すぎると冷間鍛造性を劣化させるので、0.25
％を上限とする。C is required to be 0.10% or more in order to secure the core strength of the component, but if it is too much, the cold forgeability deteriorates, so 0.25
% Is the upper limit.
Siは脱酸のために必要とするが、0.15％を超えると鍛造
時に割れ等が発生して冷間鍛造性を劣化するので、0.15
％以下とする。Si is required for deoxidation, but if it exceeds 0.15%, cracks etc. occur during forging and the cold forgeability deteriorates.
% Or less.
MnはSiと同様、脱酸作用元素として添加するが、多すぎ
ると冷間鍛造性の劣化をもたらすので、0.6％以下とす
る。Similar to Si, Mn is added as a deoxidizing element, but if it is too much, it causes deterioration of cold forgeability, so it is made 0.6% or less.
Ｂは焼入性を向上すると共に芯部強度を増大する元素で
あり、そのためには0.0005％以上を必要とするが、多す
ぎると靭性の劣化をもたらすので、0.0050％を上限とす
る。B is an element that improves the hardenability and increases the strength of the core. For that purpose, 0.0005% or more is required, but if it is too much, the toughness deteriorates, so 0.0050% is made the upper limit.
Tiは鋼中のＮをTiNで固定してBNの生成を阻止するため
上記、Ｂ添加による焼入性向上を安定化させる作用があ
るが、多すぎると靭性や冷間鍛造性の劣化をもたらすの
で、0.05％以下で添加する。Since Ti fixes N in the steel with TiN and prevents the formation of BN, Ti has the effect of stabilizing the improvement of hardenability by adding B, but if it is too much, it causes deterioration of toughness and cold forgeability. Therefore, it is added at 0.05% or less.
solAlは脱酸のために0.015％以上必要であるが、多すぎ
るとAlNが局部的に凝集し、混粒又は異常成長が発生し
易くなるので、結晶粒の粗大化を防止するために0.050
％を上限とする。solAl needs 0.015% or more for deoxidation, but if too much AlN locally aggregates, mixed grains or abnormal growth is likely to occur, so to prevent coarsening of crystal grains 0.050
% Is the upper limit.
Ｎは低いほどよく、多いとsolAlと結合してAlNを生成
し、AlNの凝集により結晶粒が異常成長するので、これ
を防止するために0.008％以下に規制する必要がある。The lower N is, the better, and when it is large, it is combined with solAl to form AlN, and crystal grains grow abnormally due to aggregation of AlN. Therefore, in order to prevent this, it is necessary to regulate to 0.008% or less.
Nbは冷間鍛造後に行なう浸炭、浸炭窒化等の表面硬化処
理時に結晶粒が粗大化するのを防止するのに有効な元素
であり、そのためには0.01％以上を添加する必要があ
る。しかし、多すぎると冷間鍛造性を劣化させるので、
上限を0.20％とする。Nb is an element effective in preventing the crystal grains from coarsening during the surface hardening treatment such as carburizing and carbonitriding performed after cold forging. For that purpose, 0.01% or more must be added. However, too much deteriorates cold forgeability, so
The upper limit is 0.20%.
上記の必須成分のほか、以下に示す元素を必要に応じて
添加することができる。In addition to the above essential components, the following elements can be added as necessary.
Ni、Cr、Moは強度を向上させる元素であり、添加すると
きはそれらの１種又は２種以上をNi≦３％、Cr≦1.5
％、Mo≦0.5％の範囲で添加する。各元素とも上限を超
えて多量に添加すると冷間鍛造性の劣化を招くと共にコ
スト高をもたらすので好ましくない。Ni, Cr and Mo are elements that improve the strength. When added, one or more of them should be Ni ≦ 3%, Cr ≦ 1.5
%, Mo ≦ 0.5%. It is not preferable to add a large amount of each element in excess of the upper limit, because it causes deterioration of cold forgeability and increases cost.
上記化学成分を有する肌焼鋼は、鋼塊或いは鋳片として
冷間鍛造に供された後、浸炭、浸炭窒化等の表面硬化処
理が施されるが、冷間鍛造性に優れ、しかも表面硬化処
理で結晶粒は粗大化せず、混粒がなく、整細粒の組織を
得ることができる。The case-hardening steel having the above chemical composition is subjected to cold forging as a steel ingot or a slab and then subjected to a surface hardening treatment such as carburizing and carbonitriding, but it is excellent in cold forgeability and has a surface hardening. By the treatment, the crystal grains do not become coarse, there is no mixed grain, and a fine-grained structure can be obtained.
次に本発明の実施例を示す。Next, examples of the present invention will be described.
（実施例） 第１表に示す化学成分（wt％）の各種肌焼鋼を50kg真空
溶解炉で溶製し、それぞれ50kg鋼塊とした後、1200℃で
32mmφ×1000mmの丸棒に鍛伸した。鍛伸後、32mmφ×10
0mmに切り出し、これを760℃×8hrの加熱後、30℃/hrの
冷却速度で冷却する球状化焼なまし処理を施し、供試材
とした。(Example) Various case-hardening steels having the chemical composition (wt%) shown in Table 1 were melted in a 50kg vacuum melting furnace to make 50kg ingots, respectively, and then at 1200 ° C.
32mmφ × 1000mm round bar was forged. 32mmφ × 10 after forging
It was cut out to 0 mm, heated at 760 ° C. for 8 hours, and then subjected to spheroidizing annealing for cooling at a cooling rate of 30 ° C./hr to obtain a test material.
これらの供試材について、まず単純圧縮試験により割れ
が発生するまでの限界圧縮率を求めた。その結果を第２
表に示す。For these test materials, first, the limit compression ratio until cracking was obtained by a simple compression test. The result is the second
Shown in the table.
また上記圧縮試験片についてオーステナイト結晶粒粗大
化温度を測定した。この測定では、冷間鍛造後の浸炭処
理温度域850〜1050℃に0.5hr保持して水冷し、オーステ
ナイト結晶粒度No.5以下の粗粒が観察され始めた温度を
オーステナイト結晶粒粗大化温度とした。その結果を第
３表に示す。Further, the austenite crystal grain coarsening temperature of the compression test piece was measured. In this measurement, the carburizing temperature range after cold forging is maintained at 850 to 1050 ° C for 0.5 hr and water-cooled, and the temperature at which coarse grains of austenite grain size No. 5 or less began to be observed was defined as the austenite grain coarsening temperature. did. The results are shown in Table 3.
第２表から明らかなように、比較例の肌焼鋼は限界圧縮
率が低いのに対し、本発明例の肌焼鋼はいずれも80％を
超える値を示し、良好な例間鍛造性を示した。 As is clear from Table 2, the case-hardening steels of the comparative examples have low critical compressibility, whereas the case-hardening steels of the present invention examples each show a value of more than 80%, showing good inter-example forgeability. Indicated.
また、第３表に示す如く、オーステナイト結晶粒粗大化
温度についても、本発明例の肌焼鋼はいずれも975℃を
超える温度を示し、耐結晶粒粗大化性に優れている。Further, as shown in Table 3, regarding the austenite crystal grain coarsening temperature, the case-hardening steels of the examples of the present invention all show a temperature of higher than 975 ° C, which is excellent in crystal grain coarsening resistance.
（発明の効果） 以上詳述したように、本発明によれば、冷間鍛造による
加工法において割れ等の欠陥が発生せず、鍛造後の表面
硬化処理でも結晶粒の粗大化を極めて効果的に防止する
ことができるので、従来のような冷間鍛造材に生ずる部
品の機械的性質の劣化、熱処理歪等の問題を解消するこ
とができ、更に必要に応じて強度、靭性の向上も可能で
ある。(Effects of the Invention) As described in detail above, according to the present invention, defects such as cracks do not occur in the processing method by cold forging, and coarsening of crystal grains is extremely effective even in the surface hardening treatment after forging. It is possible to prevent problems such as deterioration of mechanical properties of parts and heat treatment distortion that occur in cold forging materials as in the past, and it is also possible to improve strength and toughness as necessary. Is.
Claims (2)
％、Si≦0.15％、Mn≦0.6％、Ti≦0.05％、B:0.0005〜
0.0050％、solAl:0.015〜0.050％、Ｎ≦0.008％及びNb:
0.01〜0.20％を含み、残余が実質的にFeよりなることを
特徴とする冷間鍛造性と冷間鍛造後の表面硬化処理時の
耐結晶粒粗大化性に優れた冷間鍛造用肌焼鋼。1. In weight% (hereinafter the same), C: 0.10 to 0.25
%, Si ≦ 0.15%, Mn ≦ 0.6%, Ti ≦ 0.05%, B: 0.0005〜
0.0050%, solAl: 0.015-0.050%, N ≦ 0.008% and Nb:
A case for cold forging with excellent cold forgeability and resistance to coarsening of crystal grains during surface hardening treatment after cold forging, characterized by containing 0.01 to 0.20% and the balance being substantially Fe. steel.
％、Ti≦0.05％、B:0.0005〜0.0050％、solAl:0.015〜
0.050％、Ｎ≦0.008％及びNb:0.01〜0.20％を含み、更
にCr≦1.5％、Mo≦0.5％及びNi≦３％のうちの１種又は
２種以上を含み、残余が実質的にFeからなることを特徴
とする冷間鍛造性と冷間鍛造後の表面硬化処理時の耐結
晶粒粗大化性に優れた冷間鍛造用肌焼鋼。2. C: 0.10 to 0.25%, Si ≦ 0.15%, Mn ≦ 0.6
%, Ti ≦ 0.05%, B: 0.0005 to 0.0050%, solAl: 0.015 to
0.050%, N ≤ 0.008% and Nb: 0.01 to 0.20%, and further contains one or more of Cr ≤ 1.5%, Mo ≤ 0.5% and Ni ≤ 3%, with the balance being substantially Fe. A case-hardening steel for cold forging excellent in cold forgeability and resistance to coarsening of crystal grains during surface hardening treatment after cold forging.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61249144A JPH0765140B2 (en) | 1986-10-20 | 1986-10-20 | Case hardening steel for cold forging |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61249144A JPH0765140B2 (en) | 1986-10-20 | 1986-10-20 | Case hardening steel for cold forging |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63103052A JPS63103052A (en) | 1988-05-07 |
| JPH0765140B2 true JPH0765140B2 (en) | 1995-07-12 |
Family
ID=17188575
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61249144A Expired - Lifetime JPH0765140B2 (en) | 1986-10-20 | 1986-10-20 | Case hardening steel for cold forging |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0765140B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2819416B2 (en) * | 1989-03-31 | 1998-10-30 | 新日本製鐵株式会社 | Manufacturing method for high fatigue strength case-hardened products |
| JP4964063B2 (en) * | 2006-08-28 | 2012-06-27 | 株式会社神戸製鋼所 | Case-hardened steel with excellent cold forgeability and grain coarsening prevention properties and machine parts obtained therefrom |
| JP2016141821A (en) * | 2015-01-30 | 2016-08-08 | 大同特殊鋼株式会社 | Softening heat treatment method of steel material excellent in cold forgeability and crystal grain coarsening resistance |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4962318A (en) * | 1972-10-18 | 1974-06-17 | ||
| JPS4963615A (en) * | 1972-10-23 | 1974-06-20 | ||
| JPS5532777A (en) * | 1978-08-30 | 1980-03-07 | Hideo Hattori | Electrolysis of salt water |
| JPS5715657A (en) * | 1980-07-01 | 1982-01-27 | Sanden Corp | Swirl-shaped side wall finishing process and tool |
| JPS5811764A (en) * | 1981-07-15 | 1983-01-22 | Sumitomo Metal Ind Ltd | Case hardening boron steel or small heat treatment strain |
| JPS58113318A (en) * | 1981-12-28 | 1983-07-06 | Kobe Steel Ltd | Manufacture of case hardening steel |
| JPS58117856A (en) * | 1982-01-06 | 1983-07-13 | Daido Steel Co Ltd | High-strength bolt steel |
| JPS58120719A (en) * | 1982-01-08 | 1983-07-18 | Kobe Steel Ltd | Manufacture of case hardening b steel |
| JPS59182952A (en) * | 1983-04-01 | 1984-10-17 | Daido Steel Co Ltd | Case hardening steel |
-
1986
- 1986-10-20 JP JP61249144A patent/JPH0765140B2/en not_active Expired - Lifetime
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4962318A (en) * | 1972-10-18 | 1974-06-17 | ||
| JPS4963615A (en) * | 1972-10-23 | 1974-06-20 | ||
| JPS5532777A (en) * | 1978-08-30 | 1980-03-07 | Hideo Hattori | Electrolysis of salt water |
| JPS5715657A (en) * | 1980-07-01 | 1982-01-27 | Sanden Corp | Swirl-shaped side wall finishing process and tool |
| JPS5811764A (en) * | 1981-07-15 | 1983-01-22 | Sumitomo Metal Ind Ltd | Case hardening boron steel or small heat treatment strain |
| JPS58113318A (en) * | 1981-12-28 | 1983-07-06 | Kobe Steel Ltd | Manufacture of case hardening steel |
| JPS58117856A (en) * | 1982-01-06 | 1983-07-13 | Daido Steel Co Ltd | High-strength bolt steel |
| JPS58120719A (en) * | 1982-01-08 | 1983-07-18 | Kobe Steel Ltd | Manufacture of case hardening b steel |
| JPS59182952A (en) * | 1983-04-01 | 1984-10-17 | Daido Steel Co Ltd | Case hardening steel |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63103052A (en) | 1988-05-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP2010215995A (en) | Martensitic stainless steel having excellent corrosion resistance | |
| JPH08311607A (en) | Low strain carburized gear excellent in deddendum bending strength and its production | |
| JPS6311423B2 (en) | ||
| CN109790602B (en) | Steel | |
| JP4316361B2 (en) | Cooled and annealed bainite steel parts and method for manufacturing the same | |
| JPS60159155A (en) | Case hardened steel for warm forging having excellent resistance to formation of coarse grains | |
| JP3226737B2 (en) | Low decarburized spring steel | |
| JPH05263183A (en) | Carburizing case hardening steel excellent in delayed fracture resistance | |
| KR101713677B1 (en) | Steel for high nitrogen air hardened bearing with high performance on rolling contact fatigue and method producing the same | |
| JPH0765140B2 (en) | Case hardening steel for cold forging | |
| JPH07238343A (en) | Free cutting carburizing steel and heat treatment therefor before machining | |
| JP2009191322A (en) | Case-hardened steel superior in grain-coarsening resistance for use in carburized parts | |
| JPH108189A (en) | Steel for induction hardening excellent in bendability and induction hardened part excellent in bendability using the same steel | |
| JP3211627B2 (en) | Steel for nitriding and method for producing the same | |
| JP2767254B2 (en) | Method for producing Cr-Mo case hardened steel | |
| JPS5816024A (en) | Production of case hardening steel for high temperature carburization | |
| JPS634042A (en) | Case hardening steel for cold and warm forging | |
| JPS616212A (en) | Manufacture of case hardening steel for bearing | |
| JPS60208457A (en) | Alloy tool steel | |
| JPH0593244A (en) | Carburized and case-hardened steel having delayed fracture resistance | |
| KR101605964B1 (en) | Die steel and manufacturing method thereof | |
| JPH07179988A (en) | Hot tool steel excellent in high temperature strength | |
| JPH04247848A (en) | Case hardening steel for cold forging excellent in grain coarsening resistance | |
| JPH07238314A (en) | Heat treatment for free-cutting carburizing steel before processing | |
| JPH108199A (en) | Case hardening steel excellent in carburizing hardenability |