JPH1172491A - Method for predicting phase transformation of steel - Google Patents
Method for predicting phase transformation of steelInfo
- Publication number
- JPH1172491A JPH1172491A JP9233031A JP23303197A JPH1172491A JP H1172491 A JPH1172491 A JP H1172491A JP 9233031 A JP9233031 A JP 9233031A JP 23303197 A JP23303197 A JP 23303197A JP H1172491 A JPH1172491 A JP H1172491A
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- transformation
- rate
- steel
- phase
- ferrite
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Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、鋼材の品質管理、
製造方法の改善等に有益な、鋼材の金属組織を計算によ
って高精度に予測する鋼の相変態予測方法に関する。TECHNICAL FIELD The present invention relates to quality control of steel products,
The present invention relates to a method for predicting the phase transformation of steel, which is useful for improving a manufacturing method and the like, and which predicts a metal structure of a steel material with high accuracy by calculation.
【0002】[0002]
【従来の技術】鋼の化学組成および製造条件から鋼材の
金属組織と機械的性質とを定量的に予測することができ
れば、試験片を採取して実際に金相試験、機械試験等を
行う必要が無くなるので歩留まり向上に役立つ。さらに
歩留まり向上に加えて製造方法の改善等にもフィードバ
ックできるので鋼材の製造現場において重要視され、鋼
材の金属組織等の予測方法の開発が精力的に行われてき
た。2. Description of the Related Art If it is possible to quantitatively predict the metal structure and mechanical properties of a steel material from the chemical composition and manufacturing conditions of the steel, it is necessary to collect a test piece and actually perform a metal phase test, a mechanical test, and the like. Is useful for improving the yield. Further, in addition to the improvement of the yield, it is possible to feed back to the improvement of the manufacturing method and the like, so that it is regarded as important in the manufacturing site of the steel material, and the prediction method of the metal structure of the steel material has been energetically developed.
【0003】これらの予測方法においては、鋼材製造中
の個々の冶金現象ごとに計算モデルを作成し、それら全
体を統合することにより、鋼材の金属組織や機械的性質
を算出する方法が採られるのが一般的である。相変態の
予測はこの中において中核的な役割を担う。この相変態
の予測においては、オーステナイト(以後、「γ」と記
す)相から相変態によって生成するフェライト(以後、
「α」と記す)相の組織情報、すなわち、塊状フェライ
ト、パーライト、ベイナイト、マルテンサイト等の平均
粒子径、体積分率、変態温度等が算出される。[0003] In these prediction methods, a method of calculating a metallographic structure and mechanical properties of a steel material by creating a calculation model for each metallurgical phenomenon during the manufacture of the steel material and integrating them all is adopted. Is common. Prediction of phase transformation plays a central role in this. In predicting this phase transformation, ferrite (hereinafter, referred to as “γ”) generated from the austenite (hereinafter referred to as “γ”) phase by phase transformation is used.
The structure information of the phase (described as “α”), that is, the average particle diameter, volume fraction, transformation temperature, and the like of massive ferrite, pearlite, bainite, martensite, and the like are calculated.
【0004】鋼の相変態の従来の予測方法としては、例
えば、特許第2509492号公報の鋼板の材質予測法
の中において変態モデルとして概括的に開示された例が
知られている。しかし、この開示では、変態モデルの具
体的な内容は明らかではなく、どのように計算すべきか
不明確な部分もある。例えば、この特許第25094As a conventional method for predicting the phase transformation of steel, for example, there is known an example generally disclosed as a transformation model in a method for predicting the quality of a steel sheet in Japanese Patent No. 2509492. However, in this disclosure, the specific contents of the transformation model are not clear, and there is a part where it is unclear how to calculate. For example, this patent No. 25094
【0005】92号公報のNo. 92
【実施例】の段落[Example] paragraph
【0037】において「次に、生成可能と判断された組
織について任意の微小時間内の変態量の増分(ステップ
406)及びフェライトについてはこの間の生成粒数の
増分(ステップ405)を求める。」とあるが、どのよ
うに合金元素の効果を含めて計算すべきか不明である。
予測方法の発明は精度が生命であり、技術者は精度の高
い予測方法を追求する。予測方法の内容が開示されない
のでは予測精度を評価することができず、当業者に対す
る開示の意味は大きいものとは言えない。"Next, an increase in the amount of transformation within an arbitrary minute time (step 406) for the microstructure determined to be able to be formed and an increase in the number of grains formed during the ferrite (step 405) are determined." However, it is unclear how to calculate including the effects of alloying elements.
In the invention of the prediction method, accuracy is vital, and engineers pursue a highly accurate prediction method. If the details of the prediction method are not disclosed, the prediction accuracy cannot be evaluated, and the disclosure to those skilled in the art cannot be said to be significant.
【0006】γからの相変態を予測するためには、各種
変態生成物の変態開始条件、核生成速度および成長速度
を計算する必要がある。文献(小松原ら:住友金属,Vol.
42-4('90),p.104、以後、「文献1」と記す)には、ポ
リゴナル・フェライト(塊状フェライト)、ウィッドマ
ンステッテン・フェライト(針状フェライト)、パーラ
イト、ベイナイト(文献1のベイナイトを、以後の説明
では下部ベイナイトと記し、針状フェライトと下部ベイ
ナイトを併せてベイナイトと呼ぶ)、マルテンサイト変
態の開始条件、核生成および成長の式が示されている。
たとえば、ポリゴナル・フェライト(塊状フェライト)
変態の開始条件、核生成速度および成長速度はそれぞれ
次の〜式で表現できる。In order to predict the phase transformation from γ, it is necessary to calculate the transformation starting conditions, nucleation rate and growth rate of various transformation products. Literature (Komatsubara et al .: Sumitomo Metals, Vol.
42-4 ('90), p. 104, hereinafter referred to as "Reference 1" includes polygonal ferrite (bulk ferrite), Widmanstenten ferrite (acicular ferrite), pearlite, bainite (Reference 1). In the following description, the bainite will be referred to as lower bainite, and the acicular ferrite and the lower bainite will be referred to as bainite), the martensitic transformation initiation conditions, and nucleation and growth equations.
For example, polygonal ferrite (bulk ferrite)
The transformation starting conditions, nucleation rate and growth rate can be expressed by the following equations, respectively.
【0007】開始条件: |ΔG|≧0 ・・・・・・・・・・・・・・・・・・・・・・ ここで、ΔGは塊状フェライト核生成の化学的駆動力
(J/mol)である。Starting conditions: | ΔG | ≧ 0 where ΔG is the chemical driving force (J / mol).
【0008】核生成速度: I = kφ1・Dc(1-Xc)T-1/2exp{-kφ2/(ΔG2・T)}・・・ ここで、Iは核生成速度(1/(m3・s))、Dcはγ中
の炭素の拡散定数(m2/s)、Xc はγ中の炭素濃度
(モル(原子)分率)、Tは絶対温度(K)である。また
kφ1(K1/2/m5)およびkφ2(J2・K/mol2)
はともに定数である。Nucleation rate: I = kφ 1 · D c (1-X c ) T -1/2 exp {−kφ 2 / (ΔG 2 · T)} where I is the nucleation rate ( 1 / (m 3 · s)), D c is the diffusion constant of carbon in γ (m 2 / s), X c is the carbon concentration (mol (atomic) fraction) in γ, and T is the absolute temperature (K ). Kφ 1 (K 1/2 / m 5 ) and kφ 2 (J 2 · K / mol 2 )
Are both constants.
【0009】成長速度: αp = kF3{Dc(Cr-C0)2/(Cr-Ca)(C0-Ca)}1/2 ・・・・ ここでαpはパラボリック速度定数(m/s1/2)、
Cr、Caはγ/α界面でのそれぞれγ側、α側の炭素濃
度(wt%)、C0は初期炭素濃度(wt%)である。
このαpを用いて、ある時刻u(s)に生じた核のt
(s)における半径r(m)を下記式で求める。Growth rate: α p = k F3 {D c (C r -C 0 ) 2 / (C r -C a ) (C 0 -C a )} 1/2 where α p is Parabolic rate constant (m / s 1/2 ),
Cr and Ca are the carbon concentrations (wt%) on the γ side and α side, respectively, at the γ / α interface, and C 0 is the initial carbon concentration (wt%).
Using this α p , t of the nucleus generated at a certain time u (s)
The radius r (m) in (s) is obtained by the following equation.
【0010】 r(t) =αp ・(t-u)1/2 ・・・・・・・・・・・・・・・・・・ 以上の熱力学の理論式を用い、適当なkφ1、kφ2の値
を設定すればFe−C−Si−Mn系で塊状フェライト
の変態予測が可能である。ところが、一般の鋼には、S
i、Mn以外にさまざまな目的のために各種の合金元素
(Cu、Ni、Cr、Mo、B、Nb、V、Tiなど)
が添加されており、これら合金元素は相変態に大きな影
響を与える。[0010] using the r (t) = α p · (tu) 1/2 ·················· or more of the thermodynamics of the theoretical formula, appropriate kφ 1, By setting the value of kφ 2 , it is possible to predict the transformation of massive ferrite in the Fe—C—Si—Mn system. However, in general steel, S
Various alloying elements for various purposes other than i and Mn (Cu, Ni, Cr, Mo, B, Nb, V, Ti, etc.)
Is added, and these alloy elements have a great influence on the phase transformation.
【0011】上記の文献1における塊状フェライトの相
変態の予測方法においては、各種の合金元素の影響は、
この文献中に記述されている熱力学モデルで計算される
パラメータ、すなわち式、式中のΔGや式中のC
r、Caを通じて、変態開始条件、核生成、成長速度計算
に反映されることになる。In the method for predicting the phase transformation of massive ferrite in the above-mentioned Document 1, the influence of various alloying elements is as follows.
The parameters calculated by the thermodynamic model described in this document, that is, the equation, ΔG in the equation and C in the equation
r, through C a, transformation start conditions, nucleation, will be reflected in the growth rate calculated.
【0012】しかしながら、特にCr、Mo、Bなどを
含む鋼に対しては、上記方法では精度の点で不十分であ
り、新たな予測方法の開発が製造現場から望まれてい
た。However, especially for steel containing Cr, Mo, B, etc., the above method is insufficient in terms of accuracy, and development of a new prediction method has been desired from a manufacturing site.
【0013】[0013]
【発明が解決しようとする課題】本発明の目的は、合金
元素を含む鋼、なかでもCr、Mo、Bなどの合金元素
を含む鋼に対して精度が高く、かつ簡便な相変態予測方
法を提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide a highly accurate and simple method for predicting phase transformation for steels containing alloying elements, especially steels containing alloying elements such as Cr, Mo and B. To provide.
【0014】[0014]
【課題を解決するための手段】本発明者は、γからの相
変態を予測するモデルにおける各変態生成物の核生成速
度および成長速度の計算に、合金元素の影響を定数等の
形で実測データから一部採りいれることを検討した。こ
の結果、相変態の予測が飛躍的に高精度になり、かつ合
金元素についての定数等を変更することなく一定範囲の
化学組成の鋼に対してその高精度を維持できることを確
認した。すなわち、核生成速度、成長速度に対する各種
の合金元素(Si、Mn、Cu、Ni、Cr、Mo、
B、Nb、V、Tiなど)の効果を本発明では次の
[1]と[2]の項目に分けて取り扱う。In order to calculate the nucleation rate and growth rate of each transformation product in a model for predicting phase transformation from γ, the present inventor has measured the effects of alloying elements in the form of constants and the like. We considered that some data could be included. As a result, it was confirmed that the prediction of the phase transformation became remarkably high in accuracy, and that high accuracy could be maintained for a steel having a certain range of chemical composition without changing constants and the like of alloying elements. That is, various alloying elements (Si, Mn, Cu, Ni, Cr, Mo,
In the present invention, the effects of B, Nb, V, Ti, etc. are divided into the following items [1] and [2].
【0015】[1]熱力学計算にとり入れる効果 この[1]の効果は文献1等に記載された方法において
も考慮されている効果であり、合金元素がγ中に均一に
溶けることによって系の自由エネルギーを変化させ、変
態開始温度や変態速度を変化させる効果をいう。熱力学
計算を行う際に、上記〜式のような熱力学の理論式
に従って、変態開始条件、核生成速度、成長速度計算に
合金元素の効果が取り込まれる。[1] Effect taken into thermodynamic calculation The effect of this [1] is an effect considered also in the method described in Document 1 and the like. It refers to the effect of changing the free energy and changing the transformation start temperature and transformation speed. When performing thermodynamic calculations, the effects of alloying elements are taken into account for the transformation initiation conditions, nucleation rates, and growth rates according to the theoretical equations of thermodynamics as described above.
【0016】図1は、例として塊状フェライトの成長速
度に及ぼす合金元素の効果を図解した模式図である。こ
の例示した塊状フェライトの変態モデルにおいては、炭
素原子の拡散が塊状フェライト成長の律速過程である。
熱力学計算でγ/α界面でのγ側の炭素濃度Cγを上げ
る合金元素は塊状フェライトの成長速度を上げ、反対に
炭素濃度Cγを下げる元素は成長速度を下げる方向に作
用する。FIG. 1 is a schematic view illustrating the effect of alloying elements on the growth rate of massive ferrite as an example. In this exemplified bulk ferrite transformation model, diffusion of carbon atoms is the rate-determining process of bulk ferrite growth.
An alloy element that increases the carbon concentration Cγ on the γ side at the γ / α interface in the thermodynamic calculation increases the growth rate of the bulk ferrite, while an element that decreases the carbon concentration Cγ acts to decrease the growth rate.
【0017】[2]γ/α界面の移動速度に及ぼす合金
元素の効果 合金元素の効果には、[1]の熱力学に基づく効果だけ
でなく、現状の熱力学計算にはとり込めないγ/α界面
の移動速度、すなわち塊状フェライトの成長速度に及ぼ
す効果がある。すなわち、合金元素によっては、図1の
下部に示すように、炭素の濃度とは直接の関係なくαの
成長を遅らせる効果が高いものがある。この[2]の効
果は、合金元素が粒界面に偏析することにより核生成や
成長を抑制する効果など、[1]以外の影響を全て含
む。図1では、この[2]の効果を界面の“移動速度抑
制”という語を用いて表現している。[2] Effect of alloying element on moving speed of γ / α interface The effect of alloying element includes not only the effect based on thermodynamics of [1], but also γ which cannot be included in the current thermodynamic calculation. Has an effect on the moving speed of the / α interface, that is, the growth speed of massive ferrite. That is, as shown in the lower part of FIG. 1, some alloying elements have a high effect of delaying the growth of α irrespective of the concentration of carbon. The effect of [2] includes all effects other than [1], such as an effect of suppressing nucleation and growth due to segregation of alloy elements at grain boundaries. In FIG. 1, the effect of [2] is expressed by using the word “movement speed control” at the interface.
【0018】連続冷却過程で変態する場合には、この
[2]の効果は合金元素の含有率だけでなく冷却速度に
も依存する。この[2]の効果を計算にとり入れる具体
的な方法は、後述するように実験式により計算される変
態速度抑制指数を核生成速度式および成長速度式に掛け
合わせることにより行う。In the case of transformation during the continuous cooling process, the effect of [2] depends not only on the content of alloying elements but also on the cooling rate. A specific method of incorporating the effect of [2] into the calculation is to multiply the nucleation rate equation and the growth rate equation by a transformation rate suppression index calculated by an empirical formula as described later.
【0019】本発明は上記の[1]および[2]の技術
的思想に基づき、各種の合金元素を含む鋼について計算
および実験を重ね、製造現場での試作を経て完成された
もので、その要旨は下記(1)および(2)の鋼の相変
態予測方法にある。The present invention has been completed based on the above technical ideas [1] and [2], through repeated calculations and experiments on steels containing various alloying elements, and through trial production at a manufacturing site. The gist lies in the following methods (1) and (2) for predicting the phase transformation of steel.
【0020】(1)オーステナイト相からの相変態によ
って塊状フェライト、針状フェライト、パーライト、下
部ベイナイト、マルテンサイトの単一組織または複合組
織が生じ得る鋼の金属組織を予測する方法であって、下
記(a)で求めた相変態の駆動力および各界面の炭素濃
度を用い、かつ下記(b)によって得た変態速度抑制指
数FNを下記(c)の各変態生成物の核生成速度式およ
び成長速度式の各々に乗じて核生成速度および成長速度
を計算する鋼の相変態予測方法。(1) A method for predicting a metal structure of steel in which a single structure or a composite structure of massive ferrite, acicular ferrite, pearlite, lower bainite, and martensite can be generated by a phase transformation from an austenite phase. Using the driving force for phase transformation and the carbon concentration at each interface determined in (a), the transformation rate suppression index FN obtained in (b) below is used to calculate the nucleation rate expression and growth of each transformation product in (c) below. A method for predicting the phase transformation of steel by calculating the nucleation rate and growth rate by multiplying each of the rate equations.
【0021】(a)熱力学モデルにより計算される相変
態の駆動力、オーステナイト相とフェライト相の界面で
の両相の炭素濃度、オーステナイト相とセメンタイト相
の界面でのオーステナイト相の炭素濃度。(A) The driving force of the phase transformation calculated by the thermodynamic model, the carbon concentration of both phases at the interface between the austenite phase and the ferrite phase, and the carbon concentration of the austenite phase at the interface between the austenite phase and the cementite phase.
【0022】(b)合金元素の濃度、実験により定めた
定数および冷却速度の項を含む関数であって、核生成速
度および成長速度に及ぼす合金元素の影響を反映する変
態速度抑制指数FN。(B) A transformation rate suppression index FN, which is a function including the term of the concentration of the alloying element, an experimentally determined constant, and a cooling rate, which reflects the effect of the alloying element on the nucleation rate and the growth rate.
【0023】(c)熱力学において知られる各変態生成
物の核生成速度式および成長速度式。(C) nucleation and growth rate equations for each transformation product known in thermodynamics.
【0024】(2)重量%で、Cr:0.03〜5%、
Mo:0.03〜2%またはB:0.0003〜0.0
05%のうちの1種以上を含む鋼について計算する上記
(1)の鋼の相変態予測方法。(2) Cr: 0.03 to 5% by weight,
Mo: 0.03 to 2% or B: 0.0003 to 0.0
The method for predicting phase transformation of steel according to the above (1), wherein the method is calculated for steel containing at least one of the steels of at least 05%.
【0025】上記において本発明の材質予測方法が適用
される鋼は、いわゆる低合金鋼の範囲の鋼であり、多元
合金系低合金鋼または単に「多元合金系」もしくは「低
合金鋼」と略記する。In the above, the steel to which the material prediction method of the present invention is applied is a steel in the range of so-called low-alloy steel, and is abbreviated as multi-alloy low-alloy steel or simply “multi-alloy steel” or “low-alloy steel”. I do.
【0026】上記(1)において、相変態の駆動力、核
生成速度式および成長速度式は従来技術で説明された
〜式の熱力学の理論式が該当する。ただし、パーライ
トの成長速度式については、後記する式を用いる。ま
た、針状フェライトと下部ベイナイトの成長速度式につ
いては、文献1に記載されたTrivedi のモデルを用い
る。熱力学モデルについては発明の実施の形態において
補足説明するが、その骨子は文献1に記載されたモデル
と同じである。上記の予測においては、冷却条件等によ
っては、塊状フェライト等を生成しない金属組織を予測
することも当然ありうる。In the above (1), the driving force of phase transformation, the nucleation rate equation and the growth rate equation correspond to the theoretical equations of the thermodynamics described in the prior art. However, the following formula is used for the pearlite growth rate formula. For the growth rate equation of the acicular ferrite and the lower bainite, the Tridi model described in Reference 1 is used. The thermodynamic model will be supplementarily described in the embodiment of the present invention, but the gist is the same as the model described in Document 1. In the above prediction, depending on the cooling conditions and the like, it is naturally possible to predict a metal structure that does not generate massive ferrite or the like.
【0027】つぎに、上記[1]の熱力学計算にとり入
れる効果および[2]のγ/α界面の移動速度に及ぼす
合金元素の効果について詳しく説明する。Next, the effect taken into the thermodynamic calculation of [1] and the effect of the alloy element on the moving speed of the γ / α interface of [2] will be described in detail.
【0028】図1においてγ側の炭素濃度を高める合金
元素がαへの変態を促進するのはつぎの理由に基づく。
すなわち、γからαに変態する際にα側からC原子がγ
側に移動しなければCの固溶限の低いαは成長すること
ができない。もし、ある合金元素がγ/α界面のγ側の
C濃度を高める効果を有すると、その合金元素を添加す
るとγ界面からγ側内部にかけてのC濃度の勾配が大き
くなりC原子の拡散が促進され、αから排出されるCを
より速くγ側界面から除くことができα変態を促進させ
る。このような界面におけるC濃度等に対する合金元素
の効果は、後記する熱力学計算によって算出される。
図2は塊状フェライト成長の速度定数の予測例を示す図
である。Cu、Niについては熱力学計算のみで速度定
数が精度良く計算でき、速度定数に対する合金元素固有
の効果は特に無い。すなわち、Cu、Ni等について
は、従来の熱力学計算のみを行っておけば合金元素の影
響はすべてとり入れたことになる。一方、Cr、Mo、
B等は上記[2]の界面の移動速度に及ぼす効果を考慮
しないで上記[1]の熱力学計算のみ行ったのでは実体
と大きく外れた結果となる。また、図2には記載してい
ないが通常0.04wt%以下程度含まれる固溶Nb、
固溶Ti等も濃度当たりの界面移動速度を抑制する効果
がMoと同程度に大きい。本発明は、このような従来の
熱力学計算では考慮されていなかった効果を後記する方
法によりとり入れる点に大きな特徴を有する。In FIG. 1, the alloy element for increasing the carbon concentration on the γ side promotes the transformation to α for the following reason.
That is, when transforming from γ to α, the C atom
If it does not move to the side, α having a low solid solubility limit of C cannot grow. If a certain alloying element has the effect of increasing the C concentration on the γ side of the γ / α interface, the addition of that alloying element will increase the gradient of the C concentration from the γ interface to the inside of the γ side, thereby promoting the diffusion of C atoms. Thus, C discharged from α can be removed from the γ-side interface more quickly, thereby promoting α transformation. The effect of the alloy element on the C concentration and the like at the interface is calculated by thermodynamic calculation described later.
FIG. 2 is a diagram showing an example of predicting the rate constant of bulk ferrite growth. For Cu and Ni, the rate constant can be accurately calculated only by thermodynamic calculation, and there is no particular effect of the alloy element on the rate constant. That is, with respect to Cu, Ni, and the like, if only conventional thermodynamic calculations are performed, all the effects of alloy elements are taken into account. On the other hand, Cr, Mo,
For B and the like, if only the thermodynamic calculation of the above [1] is performed without considering the effect of the above [2] on the moving speed of the interface, the result is greatly different from the actual one. Further, although not shown in FIG. 2, solid solution Nb, which is usually contained at about 0.04 wt% or less,
Solute Ti and the like also have an effect of suppressing the interface movement speed per concentration as large as Mo. The present invention has a significant feature in that such effects that have not been considered in the conventional thermodynamic calculation are taken in by a method described later.
【0029】上記の本発明の相変態予測方法の特徴につ
いては、特に塊状フェライトの成長速度計算を例に挙げ
て説明したが、他には針状フェライト、パーライト、下
部ベイナイト、マルテンサイト変態があり、いずれにお
いても以上に述べた方法で合金元素の効果を取り込むこ
とが可能である。The features of the method for predicting phase transformation according to the present invention have been described with particular reference to the calculation of the growth rate of massive ferrite. Other examples include acicular ferrite, pearlite, lower bainite, and martensitic transformation. In any case, the effect of the alloy element can be taken in by the method described above.
【0030】本明細書においては、ベイナイトを針状フ
ェライトと下部ベイナイトに分けるが、これは生成開始
のエネルギー条件によって区分することができる。後の
実施例中においては針状フェライトと下部ベイナイトを
合わせてベイナイト(B)と記す。In the present specification, bainite is divided into acicular ferrite and lower bainite, which can be classified according to the energy condition of initiation of formation. In the following examples, needle-like ferrite and lower bainite are collectively referred to as bainite (B).
【0031】[0031]
【発明の実施の形態】次に、図3にしたがって本発明方
法を上記のように限定した理由について説明する。Next, the reason for limiting the method of the present invention as described above will be described with reference to FIG.
【0032】1.初期条件の設定 初期条件の設定では、再結晶γの体積率と粒径、加工硬
化した未再結晶γの体積率と粒径、加工硬化の程度(転
位密度の関数)についての条件を設定する。γ粒界はα
の核生成サイトとなるため、単位体積あたりの粒界面積
の計算に必要なγ粒径を与える必要がある。また、加工
硬化により相変態が促進されるため、加工硬化したγの
体積率と加工硬化の程度を与える必要がある。このγ粒
径や加工硬化の程度は、化学組成、加熱条件、圧延条件
等から計算により求めることができる。これらの具体的
な計算方法は、例えば、文献1に開示されている。1. Setting of initial conditions In setting of initial conditions, conditions for the volume ratio and particle size of recrystallized γ, the volume ratio and particle size of work-hardened unrecrystallized γ, and the degree of work hardening (function of dislocation density) are set. . γ grain boundary is α
It is necessary to provide a γ particle size necessary for calculating the grain boundary area per unit volume. Further, since the phase transformation is promoted by work hardening, it is necessary to give the volume ratio of work hardened γ and the degree of work hardening. The γ particle size and the degree of work hardening can be obtained by calculation from the chemical composition, heating conditions, rolling conditions, and the like. These specific calculation methods are disclosed, for example, in Reference 1.
【0033】2.各変態生成物の変態プログラム つぎに、冷却中のγより生じる各変態生成物の時間推移
を計算する。2. Transformation program of each transformation product Next, the time transition of each transformation product caused by γ during cooling is calculated.
【0034】図4は、塊状フェライト、針状フェライ
ト、パーライト、下部ベイナイト等の変態プログラムの
構成を示す図である。図4には明示していないが、マル
テンサイト変態プログラムは核生成、成長計算が含まれ
ておらず、変態開始温度を与えるのみである。文献1に
各変態生成物の変態開始条件、核生成速度および成長速
度の計算式が開示されている。相変態モデルは、(a)
熱力学モデル、および(b)核生成および成長モデルよ
り構成されているので、合金成分による効果も(a)、
および(b)のそれぞれについて考慮する必要がある。FIG. 4 is a diagram showing the structure of a transformation program for block ferrite, needle ferrite, pearlite, lower bainite, and the like. Although not explicitly shown in FIG. 4, the martensitic transformation program does not include nucleation and growth calculations, but only gives the transformation start temperature. Literature 1 discloses the transformation start conditions, the nucleation rate, and the calculation formula for the growth rate of each transformation product. The phase transformation model is (a)
Since it is composed of a thermodynamic model and (b) a nucleation and growth model, the effects of the alloy components are also (a),
And (b) need to be considered.
【0035】(a)熱力学モデル このモデルでは、γと各変態生成物とで合金元素の濃度
は同じで、炭素原子の分配のみが生じるパラ平衡を仮定
し、γ/α界面およびγ/セメンタイト界面での炭素濃
度と、相変態に伴う自由エネルギー変化を計算する。(A) Thermodynamic model In this model, it is assumed that the concentration of alloying elements is the same between γ and each transformation product, and that a para-equilibrium in which only the distribution of carbon atoms occurs is obtained, and the γ / α interface and γ / cementite Calculate the carbon concentration at the interface and the free energy change due to phase transformation.
【0036】多元合金系での計算については、Fe−C
−Mn3元系での計算方法をベースに、合金元素間(S
i、Mn、Cu、Ni、Cr、Mo、V等)の相互作用
は無視して加算則で計算する。For the calculation in the multi-element alloy system, Fe-C
-Based on the calculation method in the Mn ternary system, the alloy elements (S
The interaction of (i, Mn, Cu, Ni, Cr, Mo, V, etc.) is neglected and calculated by the addition rule.
【0037】このモデルで計算された各変態生成物の駆
動力、界面での炭素濃度が、図4の核生成および成長の
開始条件ならびに核生成速度式および成長速度式に用い
られる。The driving force of each transformation product and the carbon concentration at the interface calculated by this model are used in the nucleation and growth initiation conditions and the nucleation rate and growth rate equations in FIG.
【0038】(b)核生成および成長モデル ここで、本発明のもっとも重要な部分について説明す
る。文献1で開示した方法では、核生成速度、成長速度
に対する合金成分の影響は、核生成の駆動力と界面での
炭素濃度にのみ反映されていた。すなわち、くり返し述
べることになるが、先に示した塊状フェライトの開始条
件、核生成速度および成長速度についての理論式である
式、式および式の中の核生成の駆動力と界面での
炭素濃度にのみ反映されていた。しかしながら、本発明
では塊状フェライトの核生成速度式である式、成長速
度式である式、針状フェライトの核生成速度式(式
と同じ式であるが、定数の値は異なる)、パーライトの
成長速度式(下に示す式)、下部ベイナイトの核生成
速度式(式と同じであるが、定数の値は異なる)、の
それぞれに下記の式で得た変態速度抑制指数FNを掛
け合わせ、熱力学計算で考慮されなかった効果をとり入
れる。(B) Nucleation and growth model Here, the most important part of the present invention will be described. In the method disclosed in Reference 1, the influence of the alloy component on the nucleation rate and the growth rate was reflected only on the driving force for nucleation and the carbon concentration at the interface. In other words, as described above, the equations for the starting conditions, the nucleation rate, and the growth rate of the bulk ferrite shown above, the driving force of nucleation in the equation and the equation, and the carbon concentration at the interface Was only reflected in. However, in the present invention, a formula that is a nucleation rate formula for bulk ferrite, a formula that is a growth rate formula, a nucleation rate formula for acicular ferrite (the same formula as above, but the value of the constant is different), and a growth of pearlite The rate equation (the equation shown below) and the nucleation rate equation for the lower bainite (the same as the equation, but the value of the constant is different) are each multiplied by the transformation rate suppression index FN obtained by the following equation, Incorporate effects that were not considered in the mechanical calculations.
【0039】 G=kp・ΔT・DC(Cr-Cr cem) ・・・・・・・・・・・・・・ ここで、ΔTは過冷度(K)、Cr cemはγ/セメンタイ
ト界面でのセメンタイト側の炭素濃度、kpは定数であ
る。G = k p · ΔT · D C (C r -C r cem ) where ΔT is the degree of supercooling (K), and C r cem is The carbon concentration on the cementite side at the γ / cementite interface, k p is a constant.
【0040】 上記式は、例示として合金元素、C、Si、Mn、A
l、N、Cu、Ni、Cr、Mo、B、Nb、Ti、V
に限定して変態速度抑制指数FNをあからさまに記載し
た式である。[0040] The above formula is, for example, an alloy element, C, Si, Mn, A
1, N, Cu, Ni, Cr, Mo, B, Nb, Ti, V
It is an equation that explicitly describes the transformation rate suppression index FN limited to.
【0041】ここで、WC、WSI、WMN、WAL、WN、WCU、WN
I、WCR、WMO、WB、WNB、WTI、WVはそれぞれα中に固溶
している炭素、珪素、マンガン、アルミニウム、窒素、
銅、ニッケル、クロム、モリブデン、ホウ素、ニオブ、
チタン、バナジウムの濃度(wt%)、CRは冷却速度
(℃/s)である。また、FNWC、FNWSI、FNWMN、FNWA
L、FNWN、FNWCU、FNWNI、FNWCR、FNWMO、FNWB、FNWNB、
FNWTI、FNWV、FNCC、FCRCR、FCRMO、FCRBは実験により
決定する定数である。Here, WC, WSI, WMN, WAL, WN, WCU, WN
I, WCR, WMO, WB, WNB, WTI, WV are carbon, silicon, manganese, aluminum, nitrogen,
Copper, nickel, chromium, molybdenum, boron, niobium,
The concentrations of titanium and vanadium (wt%) and CR are cooling rates (° C./s). Also, FNWC, FNWSI, FNWMN, FNWA
L, FNWN, FNWCU, FNWNI, FNWCR, FNWMO, FNWB, FNWNB,
FNWTI, FNWV, FNCC, FCRCR, FCRMO, FCRB are constants determined by experiments.
【0042】各合金元素による、核生成、成長の抑制効
果の大小は、これらの定数の値を増減することにより表
すことができる。The magnitude of the effect of suppressing the nucleation and growth by each alloy element can be expressed by increasing or decreasing the values of these constants.
【0043】ここで変態開始条件、核生成および成長の
計算に含まれるパラメータは実測した連続冷却変態図
(Continuous Cooling Transformation Diagram:以後、
「CCT図」と記す)および金相組織写真に基づいて決
定することができる。各合金元素の[1]熱力学計算に
とり入れる効果および[2]γ/α界面の移動速度に及
ぼす合金元素の効果を固溶合金元素である、Mn、C
u、Ni、Cr、Mo、B、Nb、VおよびTiに限定
して例示すると下記のようになる。つぎの説明におい
て、[1]の効果を[熱力学]、[2]の効果を[速度
項]と略記する。Here, the parameters included in the calculation of the transformation initiation condition, nucleation and growth are shown in the continuous cooling transformation diagram (Continuous Cooling Transformation Diagram:
"CCT diagram") and a metallographic photograph. [1] The effect of each alloy element in the thermodynamic calculation and [2] the effect of the alloy element on the moving speed of the γ / α interface are Mn, C
The following is an example limited to u, Ni, Cr, Mo, B, Nb, V and Ti. In the following description, the effect of [1] is abbreviated as [thermodynamics], and the effect of [2] is abbreviated as [velocity term].
【0044】Mn: [熱力学]:Ae3点(平衡状態におけるγ/α変態開始
点)を下げる。核生成、成長も遅くなり、Ar3点(連続
冷却の場合における変態開始点。変態が微少量、例えば
0.1%、進行した温度。)が下がる。Mn: [Thermodynamics]: Lowers Ae 3 points (γ / α transformation start point in equilibrium state). Nucleation and growth are also slow, and the Ar 3 point (the starting point of transformation in the case of continuous cooling.
0.1%, advanced temperature. ) Goes down.
【0045】[速度項]:下部ベイナイト変態速度を小
さくする。[Velocity term]: The lower bainite transformation rate is reduced.
【0046】Cu: [熱力学]:Ae3点を下げる。核生成、成長も遅くな
り、Ar3点が下がる。Cu: [thermodynamics]: lowers Ae 3 points. Nucleation and growth slow down, and the Ar 3 point goes down.
【0047】[速度項]:特に無し。[Speed item]: None in particular.
【0048】Ni: [熱力学]:Ae3点を下げる。核生成、成長も遅くな
り、Ar3点が下がる。Ni: [Thermodynamics]: Lower Ae 3 points. Nucleation and growth slow down, and the Ar 3 point goes down.
【0049】[速度項]:下部ベイナイト変態速度を小
さくする。[Rate term]: Decrease the lower bainite transformation rate.
【0050】Cr: [熱力学]:Ae3点を下げる。核生成、成長も遅くな
り、Ar3点が下がる。Cr: [thermodynamics]: lowers Ae 3 points. Nucleation and growth slow down, and the Ar 3 point goes down.
【0051】[速度項]:塊状フェライト、針状フェラ
イト、パーライト、下部ベイナイト、各変態速度を小さ
くする。下部ベイナイト変態抑制の効果は冷却速度が速
くなると弱められる。[Velocity term]: Lump ferrite, acicular ferrite, pearlite, lower bainite, and lower transformation speed. The effect of lower bainite transformation suppression is reduced as the cooling rate increases.
【0052】Mo: [熱力学]:Ae3点を上げる。核生成、成長を速くす
る。Mo: [Thermodynamics]: Increase Ae 3 points. Faster nucleation and growth.
【0053】[速度項]:各変態速度を小さくするの
で、Ar3点は下がる。特にパーライト成長は極端に抑制
される。塊状フェライト、針状フェライト、下部ベイナ
イト変態抑制の効果は冷却速度が速くなると弱められ
る。[Rate term]: Since each transformation rate is reduced, the Ar 3 point is lowered. In particular, pearlite growth is extremely suppressed. The effect of suppressing bulk ferrite, acicular ferrite, and lower bainite transformation is weakened as the cooling rate increases.
【0054】B: [熱力学]:添加量が少ないので特に効果無し。B: [Thermodynamics]: There is no particular effect because the added amount is small.
【0055】[速度項]:塊状フェライト、針状フェラ
イト、下部ベイナイトの核生成、成長を抑制する。塊状
フェライト、針状フェライト変態抑制の効果は冷却速度
が速くなると弱められる。[Velocity term]: Suppresses nucleation and growth of massive ferrite, acicular ferrite, and lower bainite. The effect of suppressing bulk ferrite and acicular ferrite transformation is reduced as the cooling rate increases.
【0056】Nb、V、Ti: [熱力学]:添加量が少ないので特に効果無し。Nb, V, Ti: [Thermodynamics]: No particular effect due to small addition amount.
【0057】[速度項]:塊状フェライト、針状フェラ
イト、パーライト、下部ベイナイト、各変態速度を小さ
くする。[Velocity term]: Lump ferrite, acicular ferrite, pearlite, lower bainite, and each transformation speed are reduced.
【0058】以上の方法を用いて核生成速度と成長速度
を求めた後に、周知の拡張体積の概念を用いて、例えば
塊状フェライト変態については、平衡状態での塊状フェ
ライト体積分率XF max(すなわち塊状フェライト変態を
起こしうる最大の体積分率)に対してフェライト変態が
どれだけ進行したかの割合、XS(t)を下記式で求める
ことができる。このXS(t)が一定値を超えたとき、また
は他の変態の開始温度に到達したときに計算を終了す
る。このXS(t)の一定値としては、たとえば95%とす
るのがよい。After obtaining the nucleation rate and the growth rate using the above method, using the well-known concept of expanded volume, for example, for bulk ferrite transformation, the bulk ferrite volume fraction X F max (Equilibrium state) That is, X S (t), which is the ratio of how much the ferrite transformation has progressed to the maximum volume fraction that can cause massive ferrite transformation, can be calculated by the following equation. The calculation is terminated when this X S (t) exceeds a certain value or when the starting temperature of another transformation is reached. The constant value of X S (t) is preferably, for example, 95%.
【0059】 XS(t) =1 - exp(XE(t)/XF max)・・・・・・・・・・・・・・・・・ ここでXE(t)は、核から成長中の各塊状フェライト粒が
それぞれ独立に、重なり合わずに成長すると計算したと
きの時刻t(s)における体積の総和である。パーライ
ト変態率、針状フェライト変態率、下部ベイナイト変態
率についても同様な計算を行う。X S (t) = 1−exp (X E (t) / X F max ) where X E (t) is a kernel , Is the sum of the volumes at time t (s) when it is calculated that each of the bulk ferrite grains growing is independently grown without overlapping. Similar calculations are performed for the pearlite transformation rate, the acicular ferrite transformation rate, and the lower bainite transformation rate.
【0060】3.最終変態組織情報 各変態生成物の体積率、変態温度、フェライト粒径(塊
状フェライトと針状フェライトの平均値)を出力する。3. Final transformation structure information Outputs the volume ratio, transformation temperature, and ferrite particle size (average value of bulk ferrite and needle ferrite) of each transformation product.
【0061】上記(2)の発明は、従来の予測方法では
特に低い精度でしか予測できなかった鋼に限定した予測
方法である。すなわち、上記の(1)の発明が従来法に
比較して飛躍的にその精度を高めた鋼についての予測方
法である。重量%で、Cr:0.03〜5%、Mo:
0.03〜2%またはB:0.0003〜0.005%
のうち1種以上を含む鋼がその対象とする鋼である。C
rは、0.03%未満では変態に及ぼす影響が明確に現
れず、一方、5%を超えると本発明方法では予測精度が
低下する。Moは、0.03%未満ではCr同様に変態
に及ぼす影響は小さい。一方、2%を超えると上記の
式で表現されるようなMo濃度に対して線形に移動速度
が抑制されるという評価方法では、高濃度域での飽和す
る傾向を見積もることができず、やはり予測精度が低下
する。Bは0.0003%未満では、とくに熱間加工を
未再結晶域で強く加えた場合には変態にはほとんど影響
がなく、一方、0.005%を超えるとBの効果は飽和
してしまいMoと同じ理由により予測精度が低下する。The invention of the above (2) is a prediction method limited to steel, which can be predicted with particularly low accuracy by the conventional prediction method. That is, the invention of the above (1) is a prediction method for steel whose accuracy has been dramatically improved as compared with the conventional method. Cr: 0.03 to 5%, Mo:
0.03 to 2% or B: 0.0003 to 0.005%
Steels containing at least one of the above are steels targeted. C
If r is less than 0.03%, the effect on transformation is not clearly exhibited, while if it exceeds 5%, the prediction accuracy is reduced in the method of the present invention. If Mo is less than 0.03%, the effect on transformation is small as in the case of Cr. On the other hand, when the value exceeds 2%, the evaluation method in which the moving speed is linearly suppressed with respect to the Mo concentration as expressed by the above equation cannot estimate the tendency to saturate in a high concentration region, and the same is true. Prediction accuracy decreases. If B is less than 0.0003%, transformation is hardly affected, especially when hot working is strongly applied in the non-recrystallized region. On the other hand, if B exceeds 0.005%, the effect of B is saturated. The prediction accuracy is reduced for the same reason as Mo.
【0062】[0062]
【実施例】つぎに実施例により、本発明の効果を説明す
る。EXAMPLES Next, the effects of the present invention will be described with reference to examples.
【0063】表1は、実施例に用いた供試鋼の化学組成
を示す。Table 1 shows the chemical compositions of the test steels used in the examples.
【0064】[0064]
【表1】 [Table 1]
【0065】これらの鋼を950℃に加熱してγ化した
後、連続冷却するときの変態生成物の種類と各変態温度
の実測と予測を行った。相変態の実測は、表1に示す多
元合金系低合金鋼の試験片(直径3mm、長さ10m
m)を用いて、連続冷却時における各温度での熱膨張の
測定と、最終的に得られた金相組織の観察により行っ
た。After heating these steels to 950 ° C. to make them gamma, the types of transformation products and the respective transformation temperatures during continuous cooling were measured and predicted. The actual measurement of the phase transformation was performed using a test piece (diameter 3 mm, length 10 m) of a multi-alloy low alloy steel shown in Table 1.
Using m), the measurement was made by measuring the thermal expansion at each temperature during continuous cooling and observing the finally obtained gold phase structure.
【0066】図5は、実測した上記の鋼のCCT図であ
る。(a)は鋼符号aについて、また(b)は鋼符号b
についての実測CCT図である。図5(a)の100秒
より長時間側の塊状フェライトFとベイナイトBの間にあ
る塊状フェライト変態終了とベイナイト変態開始の間の
領域は、変態の進行が生じない領域である。FIG. 5 is an actually measured CCT diagram of the above steel. (A) is a steel code a, and (b) is a steel code b.
FIG. 6 is an actual measurement CCT diagram for. In FIG. 5A, the region between the end of the bulk ferrite transformation and the start of the bainite transformation between the massive ferrite F and the bainite B, which is longer than 100 seconds, is a region where the transformation does not proceed.
【0067】図6は、本発明方法を用いて予測したCC
T図である。(a)は鋼符号aについての、また(b)
は鋼符号bについての本発明の予測方法に基づくCCT
図である。図6(a)または(b)のベイナイト領域の
点線は、針状フェライトと下部ベイナイトを画する線で
ある。高温側の実線と点線で囲まれた温度範囲の狭い領
域が針状フェライトが生成する範囲であり、低温側の実
線と点線で囲まれた温度域の比較的広い領域が下部ベイ
ナイトが生成する範囲である。針状フェライトと下部ベ
イナイトを合わせて、ベイナイトB と表記している。ま
た、図6(a)のおよそ300秒以上の長時間側の2本
の点線の間の領域は、上記と同様に変態が停止している
領域である。図5で示した実測CCT図と図6の計算に
基づくCCT図を比べて分かるように、多元合金系低合
金鋼の相変態が精度良く再現できる結果が得られた。FIG. 6 shows the CC predicted using the method of the present invention.
It is a T figure. (A) is for steel symbol a, and (b)
Is the CCT based on the prediction method of the present invention for steel code b.
FIG. The dotted line in the bainite region in FIG. 6A or 6B is a line that separates the needle-shaped ferrite and the lower bainite. The narrow range of the temperature range surrounded by the solid line and the dotted line on the high temperature side is the range where needle-like ferrite is generated, and the relatively wide range of the temperature range surrounded by the solid line and the dotted line on the low temperature side is the range where the lower bainite is generated. It is. The combination of acicular ferrite and lower bainite is described as bainite B. The region between the two dotted lines on the long time side of about 300 seconds or longer in FIG. 6A is a region where the transformation is stopped in the same manner as described above. As can be seen by comparing the actually measured CCT diagram shown in FIG. 5 with the CCT diagram based on the calculation in FIG. 6, a result was obtained in which the phase transformation of the multi-alloy low alloy steel can be accurately reproduced.
【0068】図7は、これに対して比較例として、核生
成、成長速度に対する合金成分の効果を[1]の熱力学
計算にとどめ、本発明で用いたような方法を用いずに予
測したCCT図である。(a)は鋼符号aの、(b)は
鋼符号bの上記予測方法によるCCT図である。図7に
よれば、冷却速度の遅い領域において予測された金属組
織は実測データに合致しなかった。FIG. 7 shows, as a comparative example, the effect of the alloy component on the nucleation and growth rate, which was limited to the thermodynamic calculation of [1], and was predicted without using the method used in the present invention. It is a CCT diagram. (A) is a CCT diagram of the steel code a, and (b) is a CCT diagram of the steel code b by the above-described prediction method. According to FIG. 7, the metal structure predicted in the region where the cooling rate is low did not match the measured data.
【0069】[0069]
【発明の効果】本発明方法によれば、鋼の相変態を高精
度かつ簡便に予測できるので、鋼材の材質予測技術の向
上、ひいては鋼材製造における品質管理、さらに製造方
法の改善に資することができる。According to the method of the present invention, since the phase transformation of steel can be predicted with high precision and ease, it is possible to contribute to the improvement of the technology for predicting the material properties of steel, and further to the quality control in the production of steel and the improvement of the production method. it can.
【図1】塊状フェライトの成長速度に影響を及ぼす合金
元素の効果を図解する模式図である。FIG. 1 is a schematic diagram illustrating the effect of alloying elements on the growth rate of massive ferrite.
【図2】塊状フェライトの界面移動の速度定数に及ぼす
合金元素含有率の影響を示す図である。FIG. 2 is a view showing the effect of the content of alloying elements on the rate constant of interface movement of massive ferrite.
【図3】相変態予測方法において、一般的に行われる計
算の概略を示す図である。FIG. 3 is a diagram showing an outline of calculations generally performed in a phase transformation prediction method.
【図4】本発明の相変態予測における計算の概略を示す
図である。FIG. 4 is a diagram showing an outline of calculation in prediction of phase transformation according to the present invention.
【図5】多元合金系低合金鋼の実測CCT図である。FIG. 5 is a measured CCT diagram of a multi-alloy low alloy steel.
【図6】本発明の相変態の予測方法に基づくCCT図で
ある。FIG. 6 is a CCT diagram based on the phase transformation prediction method of the present invention.
【図7】従来の相変態の予測方法に基づくCCT図であ
る。FIG. 7 is a CCT diagram based on a conventional phase transformation prediction method.
Claims (2)
状フェライト、針状フェライト、パーライト、下部ベイ
ナイト、マルテンサイトの単一組織または複合組織が生
じ得る鋼の金属組織を予測する方法であって、下記
(a)で求めた相変態の駆動力および各界面の炭素濃度
を用い、かつ下記(b)によって得た変態速度抑制指数
FNを下記(c)の各変態生成物の核生成速度式および
成長速度式の各々に乗じて核生成速度および成長速度を
計算することを特徴とする鋼の相変態予測方法。 (a)熱力学モデルにより計算される相変態の駆動力、
オーステナイト相とフェライト相の界面での両相の炭素
濃度、オーステナイト相とセメンタイト相の界面でのオ
ーステナイト相の炭素濃度。 (b)合金元素の濃度、実験により定めた定数および冷
却速度の項を含む関数であって、核生成速度および成長
速度に及ぼす合金元素の影響を反映する変態速度抑制指
数FN。 (c)熱力学において知られる各変態生成物の核生成速
度式および成長速度式。1. A method for predicting a metal structure of steel in which a single structure or a composite structure of massive ferrite, acicular ferrite, pearlite, lower bainite, and martensite can be generated by a phase transformation from an austenite phase. Using the driving force for phase transformation and the carbon concentration at each interface determined in a), the transformation rate suppression index FN obtained in the following (b) is used to calculate the nucleation rate equation and growth rate of each transformation product in the following (c). A method for predicting phase transformation of steel, comprising calculating a nucleation rate and a growth rate by multiplying each of the equations. (A) driving force of phase transformation calculated by a thermodynamic model,
The carbon concentration of both phases at the interface between the austenite phase and the ferrite phase, and the carbon concentration of the austenite phase at the interface between the austenite phase and the cementite phase. (B) Transformation rate suppression index FN, which is a function including the alloy element concentration, an experimentally determined constant, and a cooling rate term, which reflects the effect of the alloy element on the nucleation rate and growth rate. (C) Nucleation and growth rate equations for each transformation product known in thermodynamics.
0.03〜2%またはB:0.0003〜0.005%
のうちの1種以上を含む鋼について計算することを特徴
とする請求項1の鋼の相変態予測方法。(2) Cr: 0.03 to 5% by weight, Mo:
0.03 to 2% or B: 0.0003 to 0.005%
The method for predicting phase transformation of steel according to claim 1, wherein the calculation is performed for steel containing at least one of the following.
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008007809A (en) * | 2006-06-28 | 2008-01-17 | Toyota Central Res & Dev Lab Inc | Method and device for predicting steel material structure, and program |
JP2010271084A (en) * | 2009-05-19 | 2010-12-02 | Kobe Steel Ltd | Structure prediction method for ferrite phase |
JP2012047599A (en) * | 2010-08-26 | 2012-03-08 | Kobe Steel Ltd | Bainitic phase structure prediction method |
KR101360475B1 (en) * | 2012-05-08 | 2014-02-25 | 주식회사 포스코 | Method and apparatus for predicting delamination of drawn wire rod |
-
1997
- 1997-08-28 JP JP23303197A patent/JP3941179B2/en not_active Expired - Fee Related
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008007809A (en) * | 2006-06-28 | 2008-01-17 | Toyota Central Res & Dev Lab Inc | Method and device for predicting steel material structure, and program |
JP2010271084A (en) * | 2009-05-19 | 2010-12-02 | Kobe Steel Ltd | Structure prediction method for ferrite phase |
JP2012047599A (en) * | 2010-08-26 | 2012-03-08 | Kobe Steel Ltd | Bainitic phase structure prediction method |
KR101360475B1 (en) * | 2012-05-08 | 2014-02-25 | 주식회사 포스코 | Method and apparatus for predicting delamination of drawn wire rod |
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