JPS63262420A - Production of spheroidized steel - Google Patents
Production of spheroidized steelInfo
- Publication number
- JPS63262420A JPS63262420A JP9664987A JP9664987A JPS63262420A JP S63262420 A JPS63262420 A JP S63262420A JP 9664987 A JP9664987 A JP 9664987A JP 9664987 A JP9664987 A JP 9664987A JP S63262420 A JPS63262420 A JP S63262420A
- Authority
- JP
- Japan
- Prior art keywords
- steel
- tensile stress
- cooling rate
- cooling
- spheroidized
- 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.)
- Granted
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 30
- 239000010959 steel Substances 0.000 title claims abstract description 30
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- 238000001816 cooling Methods 0.000 claims abstract description 36
- 238000005098 hot rolling Methods 0.000 claims abstract description 11
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 4
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 4
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 229910000677 High-carbon steel Inorganic materials 0.000 claims 1
- 230000009466 transformation Effects 0.000 abstract description 16
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 abstract description 13
- 229910001567 cementite Inorganic materials 0.000 abstract description 11
- 229910001562 pearlite Inorganic materials 0.000 abstract description 11
- 238000005096 rolling process Methods 0.000 abstract description 8
- 238000005242 forging Methods 0.000 abstract description 4
- 239000000203 mixture Substances 0.000 abstract description 4
- 230000000694 effects Effects 0.000 abstract description 3
- 238000000137 annealing Methods 0.000 abstract description 2
- 229910000954 Medium-carbon steel Inorganic materials 0.000 abstract 2
- 241000276425 Xiphophorus maculatus Species 0.000 abstract 2
- 229910052799 carbon Inorganic materials 0.000 abstract 1
- 238000000034 method Methods 0.000 description 21
- 239000000463 material Substances 0.000 description 3
- 238000010273 cold forging Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- 238000010583 slow cooling Methods 0.000 description 2
- 240000005979 Hordeum vulgare Species 0.000 description 1
- 235000007340 Hordeum vulgare Nutrition 0.000 description 1
- 101100230509 Neurospora crassa (strain ATCC 24698 / 74-OR23-1A / CBS 708.71 / DSM 1257 / FGSC 987) hat-1 gene Proteins 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 229910052745 lead Inorganic materials 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 239000003507 refrigerant Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
Abstract
Description
【発明の詳細な説明】
童呈上■且王立互
本発明は、冷間及び温間での鍛造加工に適する球状化鋼
の製造方法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing spheroidized steel suitable for cold and warm forging.
皿米曳艮止
一般に、機械構造用鋼を用いて各種の機械部品を製造す
る場合、棒鋼に鍛造、切削等の加工を施すことによって
、形状が整えられる。Generally, when manufacturing various machine parts using machine structural steel, the shape is adjusted by processing the steel bar by forging, cutting, etc.
上記鍛造加工のうち、冷間鍛造は、素材に厳しい変形能
が要求されるので、最終製品に所定の強度や靭性を付与
するための材料組織とは別に、できる限りにおいて低応
力にて等友釣にすぐれた変形能を有することが必要であ
る。かかる目的のための熱処理法として、従来より球状
化焼鈍が知られており、この方法によれば、パーライト
中のセメンタイトが板状から球状に変化し、素材鋼にす
ぐれた変形能を与えることができる。Among the forging processes mentioned above, cold forging requires the material to have severe deformability, so in addition to the material structure that gives the final product a certain level of strength and toughness, cold forging is performed with as low stress as possible. It is necessary to have excellent deformability. As a heat treatment method for this purpose, spheroidizing annealing has been known for a long time. According to this method, the cementite in pearlite changes from a plate shape to a spherical shape, giving excellent deformability to the steel material. can.
しかし、従来、棒鋼の製造過程において、ビレットは、
オーステナイト状態にて熱間圧延を終了して丸棒とされ
た後、オフラインにてＡ、変態点の直上又は直下にそ長
時間にわたって保持した後、徐冷することによって球状
化処理されて゛いるので、エネルギー消費量が極めて多
い。However, in the conventional manufacturing process of steel bars, billets are
After hot rolling is completed in the austenitic state to form a round bar, it is held offline for a long time just above or below the transformation point A, and then slowly cooled to form a spheroid. , energy consumption is extremely high.
、■が ° しようとするロ 占
そこで、本発明者らは、従来の球状化処理における上記
した問題を解決するために鋭意研究した結果、熱間圧延
時に制御冷却を行ない、この間に棒鋼に所定の引張応力
を付与して変態を促進すると共に、その後の圧延におい
てセメンタイトを著しく分断させることによって、後工
程における球状化処理を著しく簡単化し得ることを見出
して、本発明に至ったものである。Therefore, as a result of intensive research in order to solve the above-mentioned problems in the conventional spheroidizing process, the present inventors carried out controlled cooling during hot rolling, and during this period, the steel bar was heated to a specified level. The present invention was developed based on the discovery that by applying a tensile stress of 100% to accelerate the transformation and significantly fragmenting the cementite during subsequent rolling, it is possible to significantly simplify the spheroidization process in the subsequent process.
四 占を”°するための
本発明による球状化鋼の製造方法は、重量％でＣＯ０２
〜０．６％、
Ｓｉ０．１５〜０．３５％、
Ｍｎ ０．３−０，９％、
Ｎｉ０．２％以下、
Ｃｒ０．２％以下、
残部鉄及び不可避的不純物よりなる中高炭素鋼を熱間圧
延の途中において、中心温度が４００〜６５０℃の範囲
の温度まで、臨界冷却速度以下の冷却速度にて冷却し、
この冷却速度をＡ（”Ｃ／分）とするとき、
引張応力≧５５ ２１．３１ｏｇＡ
なる式を満足する引張応力を上記冷却中に加え、その後
、６００℃からＡ３点の間の温度にて圧延し、徐冷する
ことを特徴とする。4. The method for producing spheroidized steel according to the present invention for increasing the
~ 0.6%, Si 0.15-0.35%, Mn 0.3-0.9%, Ni 0.2% or less, Cr 0.2% or less, the balance being iron and unavoidable impurities. In the middle of rolling, the center temperature is cooled to a temperature in the range of 400 to 650 ° C. at a cooling rate below the critical cooling rate,
When this cooling rate is A ("C/min), a tensile stress that satisfies the formula: tensile stress ≧55 21.31ogA is applied during the above cooling, and then rolled at a temperature between 600 ° C and A3 point. It is characterized by slow cooling.
先ず、本発明の方法において用いる鋼の化学成分につい
て説明する。First, the chemical composition of the steel used in the method of the present invention will be explained.
本発明においては、バーライｖｉａの球状化を容易にす
るために、Ｃは０．２％以上の添加を必要とする。しか
し、０．６％よりも過多に添加する場合は、冷媒に水を
用いるような連続冷却に際して、表面部に適冷マルテン
サイト相が生成し、焼き割れを生じる。従って、本発明
においては、Ｃ量は０．２〜０．６％の範囲とする。但
し、恒温変態が可能であるときは、Ｃ量が０．６％以上
でもよい。In the present invention, C needs to be added in an amount of 0.2% or more in order to facilitate the spheroidization of the barley vias. However, if it is added in an amount exceeding 0.6%, a properly cooled martensite phase will be generated on the surface during continuous cooling using water as a refrigerant, resulting in quench cracking. Therefore, in the present invention, the C content is in the range of 0.2 to 0.6%. However, when constant temperature transformation is possible, the C content may be 0.6% or more.
零発１！１３４こよる方法は、圧延ラインにおいて、パ
ーライト変態中に応力を付加するため、焼入れ性を著し
く高める元素については、パーライト変態までの時間を
必要とし、従って、Ｎｉ及びＣｒについては、その添加
量の上限をそれぞれ０．２％とする。また、Ｓｔの添加
量は０．１５〜０．３５％の範囲とし、Ｍｎの添加量は
０．３〜０，９％の範囲とする。Since the method described in Zero Hat 1!134 applies stress during pearlite transformation in the rolling line, it requires time for elements that significantly increase hardenability to undergo pearlite transformation; therefore, for Ni and Cr, The upper limit of the amount added is 0.2%. Further, the amount of St added is in the range of 0.15 to 0.35%, and the amount of Mn added is in the range of 0.3 to 0.9%.
更に、本発明の方法においてはＣａ、Ｓ、Ｐｂ。Furthermore, in the method of the present invention, Ca, S, and Pb.
ＲＥＭ等は、焼入れ性に特に影響を与えないので、鋼は
かかる元素を含有ししていてもよい。Since REM and the like do not particularly affect hardenability, the steel may contain such elements.
本発明の方法によれば、第１図に示すように、上記した
成分組成を有する鋼を熱間圧延の途中において、質量効
果による中心と表面との間の温度差をできるだけ少なく
して、均一な球状化ｍ織を得ることができるように、中
心温度が４００〜６５０℃の範囲の温度まで、パーライ
ト変態の起こる臨界冷却速度以下の冷却速度にて冷却し
、この冷却速度をＡ （℃／分）とするとき、引張応力
≧５５−２１．３ ｌｏｇ Ａなる式を満足する引張応
力を上記冷却中に加え、その後、６００℃からＡ１点の
間の温度にて圧延し、徐冷して、棒鋼を得るものである
。According to the method of the present invention, as shown in FIG. 1, during the hot rolling of steel having the above-mentioned composition, the temperature difference between the center and the surface due to the mass effect is minimized and the temperature is uniformly rolled. In order to obtain a spheroidized m weave, the center temperature is cooled to a temperature in the range of 400 to 650°C at a cooling rate below the critical cooling rate at which pearlite transformation occurs, and this cooling rate is A (°C/ When the tensile stress is 55-21.3 log A, a tensile stress satisfying the formula: , to obtain steel bars.
従来は、鋼を高温状態から加工、冷却を繰り返し、最終
形状で室温まで冷却され、この最終冷却時にフェライト
・パーライト組織が起こり、その後にオフラインにて球
状化処理が施される。しかし、本発明の方法によれば、
上記フェライト・パーライト変態が起こる段階で引張応
力を加え、変態中のセメンタイトを予め球状化しやすい
状態にすることができる。Conventionally, steel is processed and cooled repeatedly from a high temperature state, and the final shape is cooled to room temperature. A ferrite/pearlite structure occurs during this final cooling, and then a spheroidization process is performed off-line. However, according to the method of the present invention,
By applying tensile stress at the stage where the ferrite-pearlite transformation occurs, the cementite undergoing transformation can be brought into a state where it is easy to spheroidize in advance.
即ち、本発明に従って、フェライト・パーライト変態中
に引張応力を加え、この変態後のフェライト・パーライ
ト組織にＡｔ点の直下で変形を与えた場合は、応力を与
えない場合に比べて、セメンタイト板が細かく分断され
る結果、セメンタイトが球状化に極めて適した状態とな
り、その後の処理を簡単化することができるのである。That is, according to the present invention, when tensile stress is applied during the ferrite-pearlite transformation and the ferrite-pearlite structure after this transformation is deformed immediately below the At point, the cementite plate becomes stronger than when no stress is applied. As a result of being finely divided, the cementite becomes in a state that is extremely suitable for spheroidization, and subsequent processing can be simplified.
どの現象は、高歪み速度で起こり、従って、熱間圧延中
に一度変態を起こさせる程度にまで、例えば、好ましく
は、５００〜６００℃程度まで冷却すれば、熱間圧延ラ
インでの実施が可能である。また、Ａ１変態点近傍での
加工時、加工応力が極めて低下するため、直接、温間圧
延することができる。This phenomenon occurs at high strain rates and can therefore be carried out on a hot rolling line by cooling to an extent that once the transformation occurs during hot rolling, for example, preferably to around 500-600°C. It is. Furthermore, since the processing stress is extremely reduced during processing near the A1 transformation point, direct warm rolling can be performed.
制御冷却によって、変態を起こさせるために、中心温度
が４００〜６５０℃の範囲の温度になるまで冷却する。Controlled cooling is performed until the core temperature is in the range of 400-650° C. in order to cause the transformation.
この冷却速度は鋼組成によって異なるが、臨界冷却速度
を越えることはない。This cooling rate varies depending on the steel composition, but does not exceed the critical cooling rate.
本発明において、熱間圧延中の引張応力は、冷′却部分
の前後のロールの速度調整によって、これを付加するこ
とができる。従って、本発明において、熱間圧延は、棒
及び線へのそれに限定されるものではなく、鋼板におい
ても、０．２％以上のＣを含むものであれば、同様に適
用することができる。上記制御冷却の間の引張応力は、
冷却速度に対して、前記所定の関係を満たすことが必要
であり、かかる引張応力を押えるこ、とによって、微細
に分断されたセメンタイトを１−、ることができる。In the present invention, tensile stress during hot rolling can be applied by adjusting the speed of the rolls before and after the cooling section. Therefore, in the present invention, hot rolling is not limited to rods and wires, but can be similarly applied to steel plates as long as they contain 0.2% or more of C. The tensile stress during the above controlled cooling is
It is necessary to satisfy the above-mentioned predetermined relationship with respect to the cooling rate, and by suppressing such tensile stress, finely divided cementite can be formed.
溌１わ九灰
以上のように、本発明の方法によれば、熱間圧延時に制
御冷却を行なって、棒鋼に引張応力を付与し、変態を促
進すると共に、その後の圧延においてセメンタイトを著
しく分断させるので、後工程における球状化処理を著し
く簡単化することができる。As described above, according to the method of the present invention, controlled cooling is performed during hot rolling to impart tensile stress to the steel bar, promoting transformation, and significantly fragmenting cementite during subsequent rolling. Therefore, the spheroidizing process in the subsequent process can be significantly simplified.
ヌ」１舛
以下に実施例を挙げて本発明を説明するが、本発明はこ
れら実施例により何ら限定されるものではない。The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples in any way.
Ｃ０．４９％、
Ｓｉ０．２１％、
Ｍｎ０．７４％、
Ｐ ０．０２３％、
Ｓ ０．０１７％、
Ｃｕ０．０１％、
Ｎｉ０．０１％、
Ｃｒ０．１０％、
残部鉄及び不可避的不純物よりなる３４８Ｃ鋼を熱間圧
延の途中において、中心温度が５００℃となるように２
１５℃／分の冷却速度にて冷却しながら、ｌ Ｏｋｇｆ
／ｍｍ”の引張応力を加え、その後、６５０℃で圧延し
、本発明の方法における効果を圧延直後にて示すために
、急冷した。更に、徐冷すれば、その冷却速度に応じて
、球状化が一層進行することが容易に理解されよう。Consists of C0.49%, Si0.21%, Mn0.74%, P0.023%, S0.017%, Cu0.01%, Ni0.01%, Cr0.10%, balance iron and inevitable impurities. During hot rolling of 348C steel, the temperature at the center is 500°C.
While cooling at a cooling rate of 15°C/min, l Okgf
/mm'' was applied, followed by rolling at 650°C, followed by rapid cooling to demonstrate the effect of the method of the present invention immediately after rolling.Furthermore, by slow cooling, depending on the cooling rate, a spherical shape was formed. It is easy to see that this trend will continue to progress.
第２図に上記のようにして得られた棒鋼の組織を示し、
第３図に上記の方法において、引張応力を加えることな
（、変態させた棒鋼の組織を示す。Figure 2 shows the structure of the steel bar obtained as above,
Figure 3 shows the structure of a steel bar transformed in the above method without applying tensile stress.
第２図に明らかなように、本発明の方法によれば、セメ
ンタイト組織が分断されており、従って、球状化処理に
おけるエネルギー量が大幅に低減される。As is clear from FIG. 2, according to the method of the present invention, the cementite structure is fragmented and therefore the amount of energy in the spheroidization process is significantly reduced.
第４図は、冷却速度と引張応力と得られる棒鋼における
微細セメンタイトの低硬度領域を示すグラフであって、
斜線領域部が本発明の範囲である。FIG. 4 is a graph showing cooling rate, tensile stress, and low hardness region of fine cementite in the obtained steel bar,
The shaded area is the scope of the present invention.
即ち、冷却速度に対して、前述したように、所定の関係
を満たすように、制御冷却時に引張応力を鋼に加えるこ
とによって、微細セメンタイト組織を得ることができる
。尚、図中、○で囲んだ数字はＨｖ硬さを示す。That is, a fine cementite structure can be obtained by applying tensile stress to the steel during controlled cooling so as to satisfy a predetermined relationship with respect to the cooling rate, as described above. In addition, in the figure, the numbers surrounded by circles indicate Hv hardness.
第１図は、本発明の方法における熱処理パターンを示す
グラフ、第２図は、本発明の方法によって得られた棒鋼
の組織を示す顕微鏡写真、第３図は、比較例としての棒
鋼の組織を示す顕微鏡写真、第４図は、冷却速度と引張
応力と得られる棒鋼における微細セメンタイトの低硬度
領域を示すグラフである。
第１図
ｅケ閉
第２図
第３図Fig. 1 is a graph showing the heat treatment pattern in the method of the present invention, Fig. 2 is a micrograph showing the structure of the steel bar obtained by the method of the invention, and Fig. 3 is the structure of the steel bar as a comparative example. The micrograph shown in FIG. 4 is a graph showing the cooling rate, tensile stress, and the low hardness region of fine cementite in the obtained steel bar. Figure 1: Closed Figure 2: Figure 3
Claims (1)
延の途中において、中心温度が４００〜６５０℃の範囲
の温度まで、臨界冷却速度以下の冷却速度にて冷却し、
この冷却速度をＡ（℃／分）とするとき、 引張応力≧５５−２１．３ｌｏｇＡ なる式を満足する引張応力を上記冷却中に加え、その後
、６００℃からＡ＿１点の間の温度にて圧延し、徐冷す
ることを特徴とする球状化鋼の製造方法。(1) C 0.2-0.6% by weight, Si 0.15-0.35%, Mn 0.3-0.9%, Ni 0.2% or less, Cr 0.2% or less, A medium-high carbon steel consisting of residual iron and unavoidable impurities is cooled during hot rolling to a center temperature in the range of 400 to 650°C at a cooling rate below the critical cooling rate,
When this cooling rate is A (°C/min), a tensile stress that satisfies the formula: tensile stress ≧55-21.3logA is applied during the above cooling, and then rolled at a temperature between 600°C and A_1 point. A method for producing spheroidized steel, which comprises cooling slowly.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9664987A JPH0674453B2 (en) | 1987-04-20 | 1987-04-20 | Manufacturing method of spheroidized steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9664987A JPH0674453B2 (en) | 1987-04-20 | 1987-04-20 | Manufacturing method of spheroidized steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63262420A true JPS63262420A (en) | 1988-10-28 |
| JPH0674453B2 JPH0674453B2 (en) | 1994-09-21 |
Family
ID=14170675
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9664987A Expired - Lifetime JPH0674453B2 (en) | 1987-04-20 | 1987-04-20 | Manufacturing method of spheroidized steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0674453B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113373382A (en) * | 2021-05-26 | 2021-09-10 | 东风商用车有限公司 | Cold forming method of Cr-Ni carburizing steel for Nb-containing cold forming and parts |
-
1987
- 1987-04-20 JP JP9664987A patent/JPH0674453B2/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113373382A (en) * | 2021-05-26 | 2021-09-10 | 东风商用车有限公司 | Cold forming method of Cr-Ni carburizing steel for Nb-containing cold forming and parts |
| CN113373382B (en) * | 2021-05-26 | 2022-03-25 | 东风商用车有限公司 | Cold forming method of Cr-Ni carburizing steel for Nb-containing cold forming and parts |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0674453B2 (en) | 1994-09-21 |
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