JPH07216448A - Production of steel free from coarsening of crystalline grain - Google Patents
Production of steel free from coarsening of crystalline grainInfo
- Publication number
- JPH07216448A JPH07216448A JP6042995A JP4299594A JPH07216448A JP H07216448 A JPH07216448 A JP H07216448A JP 6042995 A JP6042995 A JP 6042995A JP 4299594 A JP4299594 A JP 4299594A JP H07216448 A JPH07216448 A JP H07216448A
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- Prior art keywords
- steel
- coarsening
- forging
- time
- cast slab
- Prior art date
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- Heat Treatment Of Steel (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、浸炭処理、高周波焼入
れ処理または焼入れ処理などの熱処理後に、オーステナ
イト結晶粒の粗大化や異常成長の発生を防止する鋼と、
その、製造方法に関する。BACKGROUND OF THE INVENTION The present invention relates to a steel which prevents coarsening and abnormal growth of austenite grains after heat treatment such as carburizing, induction hardening or quenching.
It relates to a manufacturing method.
【０００２】[0002]
【従来の技術】炭素鋼、低合金鋼、軸受鋼、ばね綱、工
具鋼などの特殊鋼の多くは、それぞれの使用用途に応じ
て、焼入れ処理、高周波焼入れ処理または浸炭処理など
の各種熱処理が施されが、これらの熱処理を実施した場
合、高温に昇温・保持されるためにオーステナイト結晶
粒が成長し、粗大化を発生させることがある。粗大粒が
発生した場合には、鋼の強度や靭性および疲労強度が低
下することが知られており、実用上で問題とされてい
る。そのために、熱処理後に結晶粒が粗大化しない鋼の
検討が試みられており、Ｎｂ，Ｔｉなどの合金元素を添
加し。鋼の素地中に微細な炭化物や窒化物などの析出物
を析出させ、これら析出物の結晶粒のピンニング効果を
利用した鋼が提案されている。2. Description of the Related Art Most of special steels such as carbon steel, low alloy steel, bearing steel, spring steel, tool steel and the like are subjected to various heat treatments such as quenching treatment, induction quenching treatment or carburizing treatment according to their respective uses. However, when these heat treatments are performed, the austenite crystal grains may grow due to the temperature rising and holding at a high temperature, and coarsening may occur. It is known that the strength, toughness and fatigue strength of steel decrease when coarse grains are generated, which is a problem in practical use. Therefore, studies have been made on a steel in which crystal grains do not coarsen after heat treatment, and alloying elements such as Nb and Ti are added. A steel has been proposed in which precipitates such as fine carbides and nitrides are deposited in the base material of steel and the pinning effect of the crystal grains of these precipitates is utilized.
【０００３】しかし、現在では、処理時間の短縮を狙い
更に高い温度で熱処理を実施する場合が増加しており。
更に、粗大化特性に優れる材料が要求されている。粗大
化特性を向上させるためには、ピンニング効果を発揮す
る微細な析出物を素地中に多数析出させることが有効で
あることが知られており、上述のように合金元素を添加
することによって、炭化物や窒化物などを析出させて粗
大化特性を改善しようとする試みが実施されている。し
かし、ＮｂやＴｉを添加した場合には、鋳造時において
大型の晶出物として鋼中にＮｂやＴｉの炭化物や窒化物
が生成しやすいために、ピンニング効果を発揮するため
の有効Ｎｂ，Ｔｉ量が低減し、十分な粗大化特性を得る
ことができない。However, at present, there is an increasing number of cases where the heat treatment is carried out at a higher temperature in order to shorten the treatment time.
Further, there is a demand for a material having excellent coarsening characteristics. In order to improve the coarsening property, it is known that it is effective to precipitate a large number of fine precipitates that exhibit a pinning effect in the matrix, and by adding an alloy element as described above, Attempts have been made to improve the coarsening characteristics by precipitating carbides and nitrides. However, when Nb or Ti is added, carbides or nitrides of Nb or Ti are likely to be generated in the steel as large crystallized substances during casting, so that effective Nb, Ti for exerting the pinning effect is obtained. The amount is reduced, and sufficient coarsening characteristics cannot be obtained.
【０００４】また、これらの炭化物や窒化物を素地中に
再固溶させて有効Ｎｂ，Ｔｉ量消を増加するためには、
１３００℃以上の高温域で長時間の保持を必要とするた
めに、製品に圧延する前に、均熱処理が必要とされると
言った問題がある。また、この均熱処理を行わない場合
には、粗大化特性が向上しなのみならず、圧延後の鋼材
中に大型の炭化物や窒化物が残存するために、鋼の疲労
強度や冷間加工性などの諸特性を劣化させるなどの問題
点がある。In order to re-dissolve these carbides and nitrides in the matrix to increase the effective Nb and Ti content,
There is a problem that soaking is required before rolling into a product because it requires holding for a long time in a high temperature range of 1300 ° C. or higher. If this soaking treatment is not performed, not only the coarsening property is improved, but also large carbides and nitrides remain in the steel material after rolling, which results in fatigue strength and cold workability of the steel. There are problems such as deterioration of various characteristics.
【０００５】[0005]
【発明が解決しようとする課題】本発明は、上記のよう
な事情を背景としてなされたもので、本発明の目的とす
るところは、浸炭処理、高周波焼入れ処理または焼入れ
処理などの熱処理後に、オーステナイト結晶粒の粗大化
や異常成長の発生を防止する鋼を提供するとともに、そ
の、鋼の製造方法を提供することである。SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide austenite after heat treatment such as carburizing treatment, induction hardening treatment or quenching treatment. (EN) A steel for preventing coarsening of crystal grains and occurrence of abnormal growth, and a method for manufacturing the steel.
【０００６】[0006]
【課題を解決するための手段】本発明者は、種々の合金
元素の組合わせと溶解鋳造時の冷却条件ならびに製品の
熱間圧延・熱間鍛造条件について検討した結果、熱処理
後の結晶粒粗大化を防止するためには、鋼中の析出物を
形成させる合金元素として、ｓ−Ａｌ、Ｎ，およびＮ
ｂ，Ｔａ，Ｔｉ，Ｚｒ，Ｈｆ，Ｖの添加が有効であり、
かつ、これら元素を添加した鋼を鋳造する時点の鋳片中
心部の冷却速度を５℃／ｈ以上、かつ、製品圧延・鍛造
時の加熱・加工温度を８００〜１１５０℃とすることに
よって、優れた粗大化特性を得られることを見出だし
た。Means for Solving the Problems The present inventor has examined the combination of various alloy elements, the cooling conditions at the time of melting and casting, and the hot rolling / hot forging conditions of the product. In order to prevent the transformation, s-Al, N, and N are used as alloying elements that form precipitates in steel.
The addition of b, Ta, Ti, Zr, Hf, V is effective,
Moreover, it is excellent by setting the cooling rate of the center of the slab at the time of casting the steel to which these elements are added to 5 ° C / h or more, and the heating / working temperature during product rolling / forging to 800 to 1150 ° C It has been found that a coarsening property can be obtained.
【０００７】すなわち、本発明の結晶粒粗大化防止鋼
は、合金元素の含有率が質量％で、Ｎ ：０．０１０
〜０．０３５％、ｓ−Ａｌ：０．０１０〜０．０５０
％、を含有する、炭素鋼、Ｃｒ鋼やＣｒ−Ｍｏ鋼などの
低合金鋼、軸受鋼、ばね鋼、工具鋼、を始めとする鋼に
おいて、鋳造時の鋳片中心部を５℃／時間以上の冷却速
度で凝固させ、かつ、製品圧延または鍛造時の加熱およ
び加工中の温度を８００〜１１５０℃とすることを特徴
とする。That is, in the grain coarsening prevention steel of the present invention, the content of alloying elements is% by mass, and N: 0.010.
~ 0.035%, s-Al: 0.010-0.050
%, Carbon steel, low alloy steel such as Cr steel and Cr-Mo steel, bearing steel, spring steel, tool steel, and other steels, the center of the slab during casting is 5 ° C / hour. It is characterized in that it is solidified at the above cooling rate, and the temperature during heating and processing during product rolling or forging is set to 800 to 1150 ° C.
【０００８】加えて、質量％で、Ｎｂ：０．０１〜０．
２％、Ｔｉ：０．０１〜０．２％、Ｔａ：０．０１〜
０．３％、Ｚｒ：０．０１〜０．２％、Ｈｆ：０．０１
〜０．３％、Ｖ ：０．０３％以上、のうち１種または
２種以上を含み、炭素鋼、Ｃｒ鋼やＣｒ−Ｍｏ鋼などの
低合金鋼、軸受鋼、ばね鋼、工具鋼、を始めとする鋼に
おいて、鋳造時の鋳片中心部を５℃／時間以上の冷却速
度で凝固させ、かつ、製品圧延または鍛造時の加熱およ
び加工中の温度を８００〜１１５０℃とすることを特徴
とする。In addition, Nb: 0.01 to 0.
2%, Ti: 0.01 to 0.2%, Ta: 0.01 to
0.3%, Zr: 0.01 to 0.2%, Hf: 0.01
~ 0.3%, V: 0.03% or more, including one or more of low alloy steel such as carbon steel, Cr steel and Cr-Mo steel, bearing steel, spring steel, tool steel, In steels such as, the center of the slab during casting is solidified at a cooling rate of 5 ° C./hour or more, and the temperature during heating and processing during product rolling or forging is set to 800 to 1150 ° C. Characterize.
【０００９】以下に、各合金元素の限定理由と鋳造条件
ならびに圧延・鍛造条件について詳述する。Ｎ：０．０
１０〜０．０３５％、Ｎは本発明において重要な役割を
持つ元素であり、窒化物または炭窒化物などの析出物を
形成させるために必須の元素である。ここで、粗大化特
性を発揮させるために、０．０１０％以上を添加する。
しかし、過剰に添加すると熱間加工性や綱の肌品質を著
しく劣化させるので、Ｎの含有率の上限を０．０３５％
とする。The reasons for limiting each alloying element, casting conditions, and rolling / forging conditions will be described in detail below. N: 0.0
10 to 0.035%, N is an element having an important role in the present invention, and is an element essential for forming a precipitate such as a nitride or a carbonitride. Here, 0.010% or more is added in order to exert the coarsening property.
However, if added excessively, the hot workability and the skin quality of the rope are significantly deteriorated, so the upper limit of the N content is 0.035%.
And
【００１０】ｓ−Ａｌ：０．０１０〜０．０５０％、ｓ
−Ａｌは、Ｎと同様に本発明において重要な役割を持つ
元素であり、窒化物または炭窒化物などの析出物を形成
させるために必須の元素である。ここで、粗大化特性を
発揮させるために、０．０１０％以上を添加する。しか
し、過剰に添加すると熱間加工性を低下させるとともに
鋼中に酸化物系の非金属介在物として生成され、強度・
靭性を低下させるたに、ｓ−Ａｌの含有率の上限を０．
０５％とする。S-Al: 0.010-0.050%, s
Like Al, N is an element that plays an important role in the present invention, and is an element essential for forming precipitates such as nitrides and carbonitrides. Here, 0.010% or more is added in order to exert the coarsening property. However, if added excessively, the hot workability is deteriorated, and it is generated as an oxide-based non-metallic inclusion in the steel.
In order to reduce the toughness, the upper limit of the s-Al content is set to 0.
05%.
【００１１】Ｎｂ：０．０１〜０．２％、Ｔｉ：０．０
１〜０．２％、Ｔａ：０．０１〜０．３％、Ｚｒ：０．
０１〜０．２％、Ｈｆ：０．０１〜０．３％、Ｖ ：
０．０３％以上、Ｎｂ，Ｔｉ，Ｔａ，Ｚｒ，Ｈｆおよび
Ｖは、ｓ−Ａｌと同様に窒化物または炭窒化物などの析
出物を形成させるために添加させる元索であり、１種を
単独に、または、２種以上を複合して添加することが出
来る。これらの元素は、いずれも鋼中のＣまたはＮと結
合して窒化物、炭化物、または炭窒化物を形成するが、
ピンニング効果に有効な析出物を得て粗大化特性を発揮
させるために、０．０１０％以上、Ｖは０．０３％以上
を添加する。しかし、過剰に添加してもその効果は飽和
し、また、本発明の鋳片冷却方法を適用しても晶出物を
生成するなどの問題を生ずる。さらに、いたずらに製造
コストを上昇させるのみなので、含有率の上限を、それ
ぞれ、０．２％，０．２％，０．３％，０．２％，０．
３％とする。なお、Ｖは結晶粒微細化以外の目的で添加
される場合があるため、上限値は規定されない。しか
し、実用上においては、Ｖの添加量は非調質鋼や工具鋼
などを除き０．０３〜０．２％の範囲が望ましい。Nb: 0.01 to 0.2%, Ti: 0.0
1 to 0.2%, Ta: 0.01 to 0.3%, Zr: 0.
01-0.2%, Hf: 0.01-0.3%, V:
0.03% or more, Nb, Ti, Ta, Zr, Hf, and V are elements to be added to form precipitates such as nitrides or carbonitrides like s-Al. They can be added alone or in combination of two or more. All of these elements combine with C or N in steel to form a nitride, a carbide, or a carbonitride,
0.010% or more and V of 0.03% or more are added in order to obtain a precipitate effective for the pinning effect and to exhibit the coarsening property. However, even if added excessively, the effect is saturated, and even if the slab cooling method of the present invention is applied, problems such as formation of crystallized substances occur. Further, since the manufacturing cost is only unnecessarily increased, the upper limits of the content rates are 0.2%, 0.2%, 0.3%, 0.2%, 0.
3%. Since V may be added for the purpose other than grain refinement, the upper limit is not specified. However, in practical use, the addition amount of V is preferably in the range of 0.03 to 0.2% except for non-heat treated steel and tool steel.
【００１２】鋳片の冷却速度 鋳片の冷却速度は本発明において重要な意味を持つもの
である。実用上、鋼を製造するに当たっては、インゴッ
ト鋳造（鋼塊）または連続鋳造によって溶鋼を鋳造する
が、鋳造時の冷却速度を制御することによて、窒化物、
炭化物または炭窒化物などの晶出物生成を抑制すること
が可能である。いずれの鋳造においても最終的に凝固す
る位置は、鋳片の中心部であり、中心部ほど元素が濾化
されるために偏析や晶出物生成が生じやすくなるが、本
発明鋼においては中心部の冷却速度を５℃／ｈ以上の冷
却速度で冷却することによって、晶出物の生成を抑制す
ることが可能である。Cooling rate of slab The cooling rate of a slab has an important meaning in the present invention. Practically, in producing steel, molten steel is cast by ingot casting (steel ingot) or continuous casting, but by controlling the cooling rate during casting, nitride,
It is possible to suppress the formation of crystallized substances such as carbides or carbonitrides. In any casting, the final solidification position is the center of the slab, and segregation and crystallized product formation are more likely to occur because the element is filtered closer to the center, but in the steel of the present invention, the center By cooling the part at a cooling rate of 5 ° C./h or more, it is possible to suppress the formation of crystallized substances.
【００１３】製品圧延または鍛造時の加熱および加工中
の温度 本発明において、製品圧延または鍛造時の加熱および加
工中の温度は重要な意味っをもつものであり、粗大化温
度の向上には必要不可欠な項目である。先述したとおり
粗大化温度を高めるためには、鋼素地中に微細な析出物
をなるべく多量に析出させることが重要である。この析
出物を鍋中に微細に析出させるためには、８００℃〜１
１５０℃の温度範囲において鋼を熱間加工し析出を促進
させることに加え圧延素材中に析出している析出物を成
長させないことが重要となる。Temperature during heating and processing during product rolling or forging In the present invention, the temperature during heating and processing during product rolling or forging has an important meaning, and is necessary for improving the coarsening temperature. It is an essential item. As described above, in order to increase the coarsening temperature, it is important to deposit as much fine precipitates as possible in the steel matrix. In order to finely precipitate this precipitate in a pan, 800 ° C to 1
In the temperature range of 150 ° C., it is important not only to hot work the steel to promote the precipitation but also to prevent the precipitation of the precipitate in the rolled material from growing.
【００１４】しかし、８００℃未満の温度域では、析出
物は成長しないものの、加工中の析出量が少なく、ま
た、析出物が極めて微細になるために粗大化温度を高め
ることが出来ない。このため、熱間加工温度の下限を８
００℃とする。また、１１５０℃を越して加熱・加工さ
れた場合、素材に存在する析出物が成長するとともに、
加工中の析出量が低減し、粗大化温度の向上効果が消滅
するため、加熱・加工温度の上限温度を１１５０℃とす
る。However, in the temperature range of less than 800 ° C., although the precipitate does not grow, the amount of precipitation during processing is small and the coarsening temperature cannot be increased because the precipitate becomes extremely fine. Therefore, the lower limit of the hot working temperature is 8
Set to 00 ° C. Also, when heated and processed above 1150 ° C, the precipitates existing in the material grow and
Since the amount of precipitation during processing decreases and the effect of improving the coarsening temperature disappears, the upper limit temperature of heating / processing temperature is set to 1150 ° C.
【００１５】[0015]
【実施例】表１に示す化学組成の材料を、表２に示す冷
却速度および熱間圧延条件でφ３０ｍｍの棒鋼に製造し
た。この棒鋼を球状化焼なまし処理した後にφ３０ｍ
ｍ、高さ４５ｍｍの円柱上試験片を削り出し、７０％の
冷間加工を加えた。この素材を、１０００℃および１０
５０℃の温度に加熱し３０分保持した後に急冷し、結晶
粒度を検査した。表３に各試験材の加熱。保持後に急冷
した場合の結晶粒度を示す。EXAMPLES Materials having the chemical compositions shown in Table 1 were manufactured into steel bars of φ30 mm under the cooling rates and hot rolling conditions shown in Table 2. Φ30m after spheroidizing annealing of this steel bar
A cylindrical test piece of m and a height of 45 mm was cut out and cold-worked at 70%. This material, 1000 ℃ and 10
After heating to a temperature of 50 ° C. and holding for 30 minutes, it was rapidly cooled and the grain size was examined. Table 3 shows the heating of each test material. The crystal grain size when quenched after holding is shown.
【００１６】[0016]
【表１】 [Table 1]
【００１７】[0017]
【表２】 [Table 2]
【００１８】[0018]
【表３】 [Table 3]
【００１９】表３から明らかなように、本発明鋼である
実施例１〜１４は比較例１〜９に比べ各温度域における
オーステナイト結晶粒度は微細であることが分かる。As is clear from Table 3, Examples 1 to 14, which are steels of the present invention, have finer austenite grain sizes in each temperature range than Comparative Examples 1 to 9.
【００２０】比較例１０〜１４は実施例１の鋼を用い、
冷却速度が発明範囲を外れる場合、または、熱間加工温
度が発明範囲を外れた場合の例であるが、これらの条件
が発明範囲を外れた場合には、実施例１に比べて各温度
域におけるオーステナイト結晶粒度は粗大化しているこ
とが分かる。Comparative Examples 10 to 14 use the steel of Example 1,
This is an example of the case where the cooling rate is out of the invention range or the hot working temperature is out of the invention range. When these conditions are out of the invention range, the temperature ranges are different from those in Example 1. It can be seen that the grain size of austenite in No. 2 is coarse.
【００２１】[0021]
【発明の効果】本発明によれば、固有の合金元素の選択
と鋳造時の鋳片中心部の冷却速度の選択、および、熱間
加工時の加熱・加工温度の選択によって、浸炭処理、高
周波焼入れ処理または焼入れ処理などの熱処理後に、オ
ーステナイト結晶粒の粗大化や異常成長の発生を防止す
る鋼を提供することが出来るとともに、その、綱の製造
方法を提供することが出来る。According to the present invention, the carburizing treatment and the high frequency treatment can be performed by selecting the unique alloying element, the cooling rate of the slab center portion during casting, and the heating and processing temperature during hot working. It is possible to provide steel that prevents coarsening and abnormal growth of austenite crystal grains after a heat treatment such as a quenching treatment or a quenching treatment, and a method for manufacturing the steel.
Claims (2)
素鋼、Ｃｒ鋼やＣｒ−Ｍｏ鋼などの低合金鋼、軸受鋼、
ばね鋼、工具鋼、を始めとする鋼において、鋳造時の鋳
片中心部を５℃／ｈ以上の冷却速度で凝固させ、かつ、
製品圧延または鍛造時の加熱および加工中の温度を８０
０〜１１５０℃とすることを特徴とする、結晶粒粗大化
防止鋼の製造方法。1. A carbon steel, a Cr steel, or a Cr containing, by mass%, an alloying element content of N: 0.010 to 0.035% and s-Al: 0.010 to 0.050%. -Low alloy steel such as Mo steel, bearing steel,
In steel such as spring steel and tool steel, the central portion of the slab during casting is solidified at a cooling rate of 5 ° C./h or more, and
The temperature during heating and processing during product rolling or forging is 80
A method for producing a crystal grain coarsening prevention steel, characterized in that the temperature is 0 to 1150 ° C.
で、 Ｎｂ：０．０１〜０．２％、 Ｔｉ：０．０１〜０．２％、 Ｔａ：０．０１〜０．３％、 Ｚｒ：０．０１〜０．２％、 Ｈｆ：０．０１〜０．３％、 Ｖ ：０．０３％以上 のうち１種または２種以上を含み、炭素鋼、Ｃｒ鋼やＣ
ｒ−Ｍｏ鋼などの低合金鋼、軸受鋼、ばね鋼、工具鋼、
を始めとする鋼において、鋳造時の鋳片中心部を５℃／
ｈ以上の冷却速度で凝固させ、かつ、製品圧延または鍛
造時の加熱および加工中の温度を８００〜１１５０℃と
することを特徴とする、結晶粒粗大化防止鋼の製造方
法。2. In addition to the steel according to claim 1, mass%
, Nb: 0.01 to 0.2%, Ti: 0.01 to 0.2%, Ta: 0.01 to 0.3%, Zr: 0.01 to 0.2%, Hf: 0. 01 to 0.3%, V: 0.03% or more, including one or more of carbon steel, Cr steel and C
low alloy steel such as r-Mo steel, bearing steel, spring steel, tool steel,
In steels such as
A method for producing crystal grain coarsening prevention steel, characterized by solidifying at a cooling rate of h or more, and setting a temperature during heating and processing during product rolling or forging to 800 to 1150 ° C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6042995A JPH07216448A (en) | 1994-02-04 | 1994-02-04 | Production of steel free from coarsening of crystalline grain |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6042995A JPH07216448A (en) | 1994-02-04 | 1994-02-04 | Production of steel free from coarsening of crystalline grain |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH07216448A true JPH07216448A (en) | 1995-08-15 |
Family
ID=12651610
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6042995A Pending JPH07216448A (en) | 1994-02-04 | 1994-02-04 | Production of steel free from coarsening of crystalline grain |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07216448A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013014280A1 (en) * | 2011-07-28 | 2013-01-31 | Aktiebolaget Skf | Steel, component and method for producing steel |
| JP2016183413A (en) * | 2015-03-26 | 2016-10-20 | Ｊｆｅスチール株式会社 | Consecutive cast slab and manufacturing method therefor and manufacturing method of high tensile steel plate excellent in processability |
| WO2023019768A1 (en) * | 2021-08-16 | 2023-02-23 | 钢铁研究总院 | Large-specification long-service-life high-carbon bearing steel bar and preparation method therefor |
-
1994
- 1994-02-04 JP JP6042995A patent/JPH07216448A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013014280A1 (en) * | 2011-07-28 | 2013-01-31 | Aktiebolaget Skf | Steel, component and method for producing steel |
| JP2016183413A (en) * | 2015-03-26 | 2016-10-20 | Ｊｆｅスチール株式会社 | Consecutive cast slab and manufacturing method therefor and manufacturing method of high tensile steel plate excellent in processability |
| WO2023019768A1 (en) * | 2021-08-16 | 2023-02-23 | 钢铁研究总院 | Large-specification long-service-life high-carbon bearing steel bar and preparation method therefor |
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