JP3311457B2 - Method for producing BH steel sheet for deep drawing excellent in dent resistance and surface distortion resistance - Google Patents
Method for producing BH steel sheet for deep drawing excellent in dent resistance and surface distortion resistanceInfo
- Publication number
- JP3311457B2 JP3311457B2 JP00063194A JP63194A JP3311457B2 JP 3311457 B2 JP3311457 B2 JP 3311457B2 JP 00063194 A JP00063194 A JP 00063194A JP 63194 A JP63194 A JP 63194A JP 3311457 B2 JP3311457 B2 JP 3311457B2
- Authority
- JP
- Japan
- Prior art keywords
- less
- resistance
- steel sheet
- nitriding
- dent resistance
- 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.)
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- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Sheet Steel (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は耐デント性ならびに耐面
ひずみ性に優れた深絞り用ＢＨ鋼板の製造方法に関する
ものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a BH steel sheet for deep drawing having excellent dent resistance and surface distortion resistance.
【０００２】[0002]
【従来の技術】ＴｉやＮｂを極低炭素鋼に添加し、固溶
Ｃ，Ｎを炭窒化物の形で固定したＩＦ鋼板(Interstitia
l atom free steel sheet)は優れた深絞り性を有する冷
延鋼板として広く使用されている。しかし、この鋼板の
弱点は軟質のため、耐面ひずみ性には優れているが、耐
デント性が劣り、自動車用の外板等に適用すると成形後
外力を加えると形状が容易に崩れる欠点がある。一方、
耐デント性を向上させるには降伏点を高めることが有効
であることが知られているが、この場合形状凍結性が悪
くなり面ひずみが生じやすくなる。2. Description of the Related Art An IF steel sheet (Interstitia) in which Ti and Nb are added to ultra-low carbon steel and solid solution C and N are fixed in the form of carbonitride.
l atom free steel sheet) is widely used as a cold rolled steel sheet having excellent deep drawability. However, the weak point of this steel sheet is its softness, so it has excellent surface strain resistance, but its dent resistance is inferior, and when it is applied to automotive outer plates, etc., it has the disadvantage that its shape easily collapses when external force is applied after molding. is there. on the other hand,
It is known that increasing the yield point is effective for improving the dent resistance. However, in this case, the shape freezing property is deteriorated, and surface distortion is likely to occur.
【０００３】耐デント性ならびに耐面ひずみ性を有する
鋼板の製造方法として、最近表層をハイテン化した複層
鋼板による製造方法を開示した特開平４−１４３２２７
号公報がある。しかし、複層鋼板による製造法は大幅な
コスト増となる。As a method of manufacturing a steel sheet having dent resistance and surface strain resistance, Japanese Patent Application Laid-Open No. 4-143227 has recently disclosed a method of manufacturing a multi-layer steel sheet having a high-tensile surface layer.
There is an official gazette. However, the production method using a multi-layer steel plate causes a large increase in cost.
【０００４】一方、表面近傍層だけをハイテン化する方
法として、浸炭処理あるいは窒化処理がよく知られてお
り、特開平３−２４３７５３号公報に浸炭・窒化処理に
より表面近傍で強度の高い冷延鋼板ならびにその製造方
法が開示されている。しかし、この方法においては、表
層をハイテン化することにより、耐デント性が向上する
という現象が述べられているのみで、耐デント性を向上
させるための具体的条件は定量的には、一切述べられて
いない。またＢＨ性については全く検討されておらず、
耐デント性と耐面ひずみ性を同時に満足し、かつＢＨ性
を付与する製造方法については全く開示されていないだ
けでなく、示唆する結果も提示されていない。On the other hand, carburizing or nitriding is well known as a method for increasing the strength of only the layer near the surface. A cold-rolled steel sheet having a high strength near the surface by carburizing and nitriding is disclosed in Japanese Patent Application Laid-Open No. 3-243755. And a method for producing the same. However, in this method, only the phenomenon that the dent resistance is improved by increasing the surface strength of the surface layer is described, and specific conditions for improving the dent resistance are quantitatively described. Not been. Also, the BH property has not been studied at all,
A production method that simultaneously satisfies dent resistance and surface strain resistance and imparts BH properties is not disclosed at all, but no suggestive results are presented.
【０００５】[0005]
【発明が解決しようとする課題】本発明は、今まで、大
幅なコスト高を伴う複層鋼板でだけで可能であった耐デ
ント性と耐面ひずみ性を同時に満足する冷延鋼板を安価
に製造する方法を提供するものである。SUMMARY OF THE INVENTION The present invention provides a low-cost cold-rolled steel sheet that simultaneously satisfies both dent resistance and surface strain resistance, which has been possible only with a multi-layer steel sheet at a great cost. It provides a manufacturing method.
【０００６】[0006]
【課題を解決するための手段】本発明者らは耐デント性
と耐面ひずみ性を同時に満足する冷延鋼板の製造方法を
検討し、鋼の成分と窒化条件を最適化することにより連
続焼鈍でこの種の鋼を製造できることを見いだした。ま
た、窒化冷却条件を限定することにより適正なＢＨ性を
付与できることが明らかになった。Means for Solving the Problems The present inventors have studied a method for producing a cold-rolled steel sheet which simultaneously satisfies both the dent resistance and the surface strain resistance, and optimize the composition of the steel and the nitriding conditions to thereby achieve continuous annealing. Found that this kind of steel could be produced. In addition, it has been clarified that proper BH properties can be imparted by limiting the nitriding cooling conditions.
【０００７】本発明はこのような知見に基づくものであ
り、その要旨とするところは、重量比で Ｃ ：０．００５％以下、 Ｎ ：０．０１％以下、 Ｍｎ：１．５％以下、 Ｓｉ：１．０％以下、 Ｐ ：０．１％以下、 Ａｌ：０．００５％以上、０．２％以下、 Ｓ ：０．０２％以下、 総量が０．０２％以上のＴｉおよびＮｂのいずれか一方
または双方、 かつ５５｛Ｔｉ／４８＋Ｎｂ／９３−Ｃ／１２−Ｎ／１４｝−０．０１＞０ なる条件を満足し、必要に応じＢ：０．０００２％以
上、０．００２％以下を含有し、残部Ｆｅおよび不可避
的不純物からなる鋼を、冷延後、連続焼鈍炉内で再結晶
焼鈍をした後、６００℃以上、８００℃以下の窒化雰囲
気でＮＨ3 の濃度（％）とこの温度域での滞在時間
（秒）の積が５０以上、５００以下の条件で窒化処理
し、その後５００℃までの平均冷速を５０℃/sec以上、
１００℃/sec以下で冷却することを特徴とする耐デント
性ならびに耐面ひずみ性に優れた深絞り用ＢＨ鋼板の製
造方法にある。The present invention is based on such findings, and the gist of the present invention is that C: 0.005% or less, N: 0.01% or less, Mn: 1.5% or less by weight ratio, Si: 1.0% or less, P: 0.1% or less, Al: 0.005% or more, 0.2% or less, S: 0.02% or less, Total amount of Ti and Nb of 0.02% or more Either or both, and the condition of 55 {Ti / 48 + Nb / 93-C / 12-N / 14} -0.01> 0 is satisfied, and if necessary, B: 0.0002% or more, 0.002% The steel containing the following and the balance consisting of Fe and unavoidable impurities is subjected to recrystallization annealing in a continuous annealing furnace after cold rolling, and then the NH 3 concentration (%) in a nitriding atmosphere of 600 ° C. or more and 800 ° C. or less. And the product of stay time (sec) in this temperature range is 50 or more and 500 or less. Nitriding treatment, then the average cooling rate up to 500 ℃ 50 ℃ / sec or more,
A method for producing a deep drawing BH steel sheet having excellent dent resistance and surface distortion resistance characterized by cooling at a rate of 100 ° C./sec or less.
【０００８】以下に、本発明について詳細に説明する。
本発明の成分の限定理由は次の通りである。Ｔｉおよび
Ｎｂのいずれか一方または双方を５５｛Ｔｉ／４８＋Ｎ
ｂ／９３−Ｃ／１２−Ｎ／１４｝−０．０１＞０なる関
係を満足し、かつＴｉおよびＮｂのいずれか一方または
双方の添加量の和を０．０２％以上と限定したのは、鋼
中のＣおよびＮを析出物の形で固定し、固溶のＣ，Ｎを
冷延時にほとんど存在させずにスムースな結晶回転を可
能にすることにより、その後の再結晶焼鈍で製品の深絞
り性を良好ならしめるに有利な方位である（１１１）
〈１１２〉，（５５４）〈２２５〉等の集積度の高い集
合組織を有する鋼板を得ることができること、それに、
窒化時に必要な強度の上昇が得られるためである。Hereinafter, the present invention will be described in detail.
The reasons for limiting the components of the present invention are as follows. Either or both of Ti and Nb at 55 ° Ti / 48 + N
The reason for satisfying the relationship of b / 93-C / 12-N / 14｝ -0.01> 0 and limiting the sum of the addition amounts of one or both of Ti and Nb to 0.02% or more is as follows. By fixing C and N in steel in the form of precipitates and allowing smooth crystal rotation with almost no solid solution of C and N during cold rolling, the product can be recrystallized by subsequent recrystallization annealing. This orientation is advantageous for improving deep drawability (111)
<112>, (554) <225>, etc., a steel sheet having a texture with a high degree of accumulation can be obtained.
This is because a required increase in strength during nitriding can be obtained.
【０００９】一方、Ｃ：０．００５％以下、Ｎ：０．０
１％以下、Ｓ：０．０２％以下としたのはこれらの量を
超えて、Ｃ，Ｎ，Ｓを添加すると製品の加工性を損なう
のみならず上記条件式を満足せしめるに必要なＴｉある
いはＮｂの量が多くなり、不必要に製造コストを高くす
るためである。On the other hand, C: 0.005% or less, N: 0.0
The addition of C, N, and S in excess of 1% or less and S: 0.02% or less in these amounts not only impairs the workability of the product but also reduces Ti or Ti required to satisfy the above conditional expression. This is because the amount of Nb increases and the manufacturing cost is unnecessarily increased.
【００１０】なお、他の成分として強度向上のために通
常含まれる成分、即ちＳｉ，Ｍｎ，Ｐの上限をそれぞれ
Ｓｉ：１．０％以下、Ｍｎ：１．５％以下、Ｐ：０．１
％以下としたのは、これ以上の添加は加工性を劣化する
ためである。The other components usually included for improving the strength, that is, the upper limits of Si, Mn, and P are respectively 1.0% or less for Si, 1.5% or less for Mn, and 0.1% for P.
The reason for setting the content to not more than% is that the addition of more than 10% deteriorates workability.
【００１１】また、Ｂの添加は２次加工性を高めるの
で、必要に応じ０．０００２％以上のＢを添加すること
は効果的であるが、０．００２０％超になると加工性の
劣化が著しくなるので、上限は０．００２０％とする。
Ａｌは溶鋼での確実な脱酸を可能にするために少なくと
も０．００５％の添加が必要であるが、過度の添加は加
工性を劣化するので上限を０．２％とした。Further, the addition of B enhances the secondary workability, so it is effective to add B in an amount of 0.0002% or more as necessary. However, if it exceeds 0.0020% , the workability deteriorates. Therefore, the upper limit is made 0.0020 %.
Al must be added in an amount of at least 0.005% in order to enable reliable deoxidation in molten steel. However, excessive addition deteriorates workability, so the upper limit was made 0.2%.
【００１２】次に製造プロセスの限定について説明す
る。本発明鋼の特性は加熱条件、熱延条件に大きく依存
しないので、特に限定する必要はない。即ち、スラブを
再加熱した後熱延しても、直接鋳造後熱延しても差し支
えない。また、熱延を省略した薄鋳片でも構わない。冷
延条件も強いて限定する必要はないが、深絞り性の好ま
しい集合組織を発達させるには７０％以上の冷延率が好
ましい。再結晶焼鈍条件については、鋼板が再結晶する
前に窒化雰囲気にさらされると、再結晶が顕著に抑制さ
れるので、窒化雰囲気となる前に再結晶する必要があ
る。Next, the limitation of the manufacturing process will be described. Since the properties of the steel of the present invention do not largely depend on the heating conditions and hot rolling conditions, there is no particular limitation. That is, the slab may be hot-rolled after reheating or may be directly hot-rolled after casting. Also, a thin cast piece from which hot rolling is omitted may be used. It is not necessary to limit the conditions of the cold-rolling, but a cold-rolling ratio of 70% or more is preferable in order to develop a texture having favorable deep drawability. Regarding the recrystallization annealing conditions, if the steel sheet is exposed to a nitriding atmosphere before recrystallization, recrystallization is remarkably suppressed, so it is necessary to recrystallize before the nitriding atmosphere.
【００１３】本発明の最も重要なプロセス条件は窒化条
件で、本発明鋼を６００℃以上、８００℃以下の窒化雰
囲気でＮＨ3 の濃度（％）とこの温度域での滞在時間
（秒）の積が５０以上、５００以下の条件で窒化処理す
ることにより耐デント性と耐面ひずみ性を同時に満足す
る冷延鋼板を製造することができる。窒化温度が６００
℃以下で耐デント性と耐面ひずみ性を同時に満足する冷
延鋼板を製造することができないのは、窒化が表面近傍
だけに限られるため、必要な特性を得る窒化が実現でき
ないためと考えられる。また、８００℃以上になると雰
囲気中のアンモニアが分解し、鋼板表面で有効に作用す
る活性な窒素濃度が下がることが原因で必要な特性を得
られないものと思われる。ＮＨ3 の濃度（％）とこの温
度域での滞在時間（秒）の積が５０以下で耐デント性と
耐面ひずみ性を同時に満足する冷延鋼板を製造すること
ができない理由は明確ではないが、必ずしも窒化が十分
に進行しないのではなく、耐デント性を高める板厚方向
の窒化分布が達成されないのが原因と思われる。一方、
ＮＨ3 の濃度（％）とこの温度域での滞在時間（秒）の
積が５００以上で耐デント性と耐面ひずみ性を同時に満
足する冷延鋼板を製造することができないのは、鋼板の
降伏強度が高くなり過ぎ、形状凍結性が劣化し、面ひず
みが生じるためと考えられる。The most important process condition of the present invention is the nitriding condition. The steel of the present invention is subjected to a nitriding atmosphere at a temperature of 600 ° C. or more and 800 ° C. or less of the NH 3 concentration (%) and the residence time (second) in this temperature range. By performing the nitriding treatment under the condition of an area of 50 or more and 500 or less, a cold-rolled steel sheet satisfying both the dent resistance and the surface strain resistance can be manufactured. Nitriding temperature is 600
The reason why it is not possible to manufacture a cold-rolled steel sheet that simultaneously satisfies the dent resistance and the surface strain resistance at a temperature of less than or equal to ° C is because nitriding is limited to the vicinity of the surface, and it is not possible to realize nitriding to obtain the required characteristics. . If the temperature exceeds 800 ° C., ammonia in the atmosphere is decomposed, and it is considered that necessary characteristics cannot be obtained due to a decrease in the concentration of active nitrogen effectively acting on the surface of the steel sheet. It is not clear why a product of the NH 3 concentration (%) and the residence time (sec) in this temperature range of 50 or less cannot produce a cold-rolled steel sheet satisfying both dent resistance and surface strain resistance at the same time. However, it is considered that the nitriding does not always proceed sufficiently, and the nitriding distribution in the plate thickness direction for improving the dent resistance is not achieved. on the other hand,
When the product of the NH 3 concentration (%) and the residence time (second) in this temperature range is 500 or more, a cold rolled steel sheet that simultaneously satisfies the dent resistance and the surface strain resistance cannot be manufactured because of the steel sheet. It is considered that the yield strength becomes too high, the shape freezing property is deteriorated, and a surface strain occurs.
【００１４】冷却条件の限定は、上記の窒化処理をした
材料を５００℃まで冷却する際の冷速を５０℃/sec未満
とするとＢＨ性は２０MPa 以下となり、高いＢＨが得ら
れない。これは冷却速度が遅いと、固溶Ｎ量が低くなり
過ぎるためと考えられる。また、冷速が１００℃/sec超
になると成形時にストレッチャーストレインが発生し、
表面品位の劣化を招く。これは、上記と逆に固溶Ｎ量が
高くなり過ぎるためと考えられる。[0014] The cooling conditions are limited as follows. If the cooling rate at the time of cooling the nitrided material to 500 ° C is less than 50 ° C / sec, the BH property becomes 20 MPa or less and high BH cannot be obtained. This is considered to be because if the cooling rate is low, the amount of dissolved N becomes too low. If the cooling speed exceeds 100 ° C./sec, a stretcher strain occurs during molding,
This causes deterioration of surface quality. It is considered that this is because, contrary to the above, the amount of solute N becomes too high.
【００１５】[0015]
【実施例】本発明の実施例を、比較例とともに説明す
る。表１に示した成分組成を有する鋼を種々の条件で窒
化処理をした。これらの条件と製品特性を表２に示す。
ここでの材料は、連続鋳造スラブを１２００℃に加熱
し、約９３０℃で仕上圧延した４mm厚の熱延板を８０％
冷延し、連続焼鈍の前半で８００℃で３０秒の再結晶焼
鈍をし、その後窒化処理をしたものである。実験番号１
〜１３，１５，１６は同じ材料を用いてプロセス条件の
影響を明確にした。また、実験番号１７から２４までは
鋼種の影響を明らかにした。EXAMPLES Examples of the present invention will be described together with comparative examples. Steels having the component compositions shown in Table 1 were subjected to nitriding treatment under various conditions. Table 2 shows these conditions and product characteristics.
The material used here was a continuous cast slab heated to 1200 ° C, and a 4mm-thick hot rolled sheet that was finish-rolled at about 930 ° C was 80%
It is cold rolled, recrystallized and annealed at 800 ° C. for 30 seconds in the first half of continuous annealing, and then subjected to nitriding treatment. Experiment number 1
13, 15, and 16 clarified the influence of process conditions using the same material. In addition, the effects of steel types were clarified in Experiment Nos. 17 to 24.
【００１６】降伏点（ＹＰ）が２５０MPa 以上になると
面ひずみが生じやすいという従来の知見に基づきＹＰ＜
２５０MPa ならば面ひずみが発生しないとした。また、
デント性の指標は図１に示す実験装置により鋼板に負荷
を与えた後、残った永久凹み量が試料の中心部で５０μ
ｍになる荷重でもって表した。ＢＨは引張試験で２％の
ひずみを与え、その後１７０℃で２０分の時効処理をし
た後、再び引張試験をし、このときの降伏応力から最初
の引張試験の２％のひずみ時の応力を引いた値で示す。Based on the conventional knowledge that when the yield point (YP) exceeds 250 MPa, surface strain is likely to occur, YP <
If it is 250 MPa, no surface strain is generated. Also,
After applying a load to the steel plate using the experimental device shown in FIG. 1, the amount of remaining dent was 50 μm at the center of the sample.
m. BH gives a 2% strain in a tensile test, then performs an aging treatment at 170 ° C. for 20 minutes, and then performs a tensile test again. From the yield stress at this time, the stress at the 2% strain in the first tensile test is calculated. Shown by subtracted value.
【００１７】[0017]
【表１】 [Table 1]
【００１８】[0018]
【表２】 [Table 2]
【００１９】本発明範囲の実験番号３，４，５，６，
７，８，１１，１５，１７，１８，１９，２０，２１，
２２は面ひずみ指数、デント性指数ともに良好で、ＢＨ
性にも優れている。Experiment numbers 3, 4, 5, 6, within the scope of the present invention
7 , 8 , 11, 15 , 17, 18 , 19, 20 , 21,
22 shows good surface strain index and good dent index, and BH
Also excellent in nature.
【００２０】一方、実験番号１は窒化処理をしていない
ため、耐デント性が劣る。実験番号２は窒化が十分行な
われず、十分な耐デント性が得られなかった。実験番号
９は窒化過剰のため耐面ひずみ性に支障をきたしただけ
でなく、表層が硬化し過ぎて脆くなり低いデント荷重で
表層に割れが生じ、耐デント性も著しく劣化した。実験
番号１０は窒化温度が高過ぎ、アンモニアが鋼板表面で
活性な窒素と水素に分解する前に、雰囲気中で分解を起
こし、不活性な窒素になる量が多くなるため窒化が十分
に行なわれず、十分な耐デント性が得られなかった。実
験番号１２は窒化温度が低く、窒化が十分行なわれず、
十分な耐デント性が得られなかった。実験番号１３は窒
化温度から５００℃までの平均冷速が５℃/secと小さい
ため冷却中に固溶の窒素が析出し、ＢＨ量が低くなっ
た。一方、冷速が１２０℃/secと大きかった実験番号１
６では窒化時の残存した固溶の窒素が析出する時間がほ
とんどなく多くの固溶窒素が残存したためＢＨ量は高い
がストレッチャーストレインが発生した。５５｛Ｔｉ／
４８＋Ｎｂ／９３−Ｃ／１２−Ｎ／１４｝−０．０１＞
０の条件を満足しなかった材料を用いた実験番号２３，
２４では窒化時に析出物を形成する窒化前の固溶のＴ
ｉ，Ｎｂの量が不足あるいは欠乏していたため、窒化の
効果が十分に出ず、十分な耐デント性が得られなかっ
た。On the other hand, in Experiment No. 1, since no nitriding treatment was performed, the dent resistance was poor. In Experiment No. 2, nitriding was not sufficiently performed, and sufficient dent resistance was not obtained. In Experiment No. 9, not only the surface strain resistance was impaired due to excessive nitridation, but also the surface layer was excessively hardened and became brittle. In Experiment No. 10, the nitriding temperature was too high, and before the ammonia was decomposed into active nitrogen and hydrogen on the surface of the steel sheet, it was decomposed in the atmosphere, and the amount of inactive nitrogen was increased. , Sufficient dent resistance could not be obtained. In Experiment No. 12, the nitriding temperature was low and the nitriding was not sufficiently performed.
Sufficient dent resistance was not obtained. In Experiment No. 13, since the average cooling rate from the nitriding temperature to 500 ° C. was as small as 5 ° C./sec, solid solution nitrogen was precipitated during cooling, and the BH amount was low. On the other hand, Experiment No. 1 in which the cooling rate was as large as 120 ° C./sec
In No. 6, stretcher strain was generated although the amount of BH was high, because there was little time for the remaining solid solution nitrogen to precipitate during nitridation and a large amount of solid solution nitrogen remained. 55 ｛Ti /
48 + Nb / 93-C / 12-N / 14} -0.01>
Experiment No. 23 using a material that did not satisfy the condition 0,
24, the solid solution T before nitriding, which forms a precipitate during nitriding,
Since the amounts of i and Nb were insufficient or deficient, the nitriding effect was not sufficiently obtained, and sufficient dent resistance was not obtained.
【００２１】[0021]
【発明の効果】本発明によれば、今まで、複層鋼板のよ
うな大幅なコスト増なしには不可能であった耐面ひずみ
性と耐デント性を同時に満足する鋼板を、安価に製造で
き工業的に価値の高い発明である。また、ＢＨ性も付与
され、成形後の塗装処理によりさらに耐デント性が向上
する。According to the present invention, a steel plate which simultaneously satisfies both the surface strain resistance and the dent resistance, which was not possible without a significant increase in cost, such as a multilayer steel plate, has been manufactured inexpensively. This is an industrially valuable invention. In addition, BH property is imparted, and dent resistance is further improved by coating treatment after molding.
【図１】デント性の測定の実験方法の概要を示した説明
図である。FIG. 1 is an explanatory diagram showing an outline of an experimental method for measuring dent properties.
Claims (2)
％以上、かつ 55｛Ｔｉ／48＋Ｎｂ／93−Ｃ／12−Ｎ／14]-0.01>0なる
条件を満足し、 残部Ｆｅおよび不可避的不純物からなる鋼を、冷延後、
連続焼鈍炉内で再結晶焼鈍をした後、６００℃以上、８
００℃以下の窒化雰囲気でＮＨ3 の濃度（％）とこの温
度域での滞在時間（秒）の積が５０以上、５００以下の
条件で窒化処理をし、その後５００℃までの平均冷速を
５０℃/sec以上、１００℃/sec以下で冷却することを特
徴とする耐デント性ならびに耐面ひずみ性に優れた深絞
り用ＢＨ鋼板の製造方法。1. A weight ratio of C: 0.005% or less, N: 0.01% or less, Mn: 1.5% or less, Si: 1.0% or less, P: 0.1% or less, Al: 0.005% or more, 0.2% or less, S: 0.02% or less, and either or both of Ti and Nb in a total amount of 0.02%
% Or more, and the condition of 55 ° Ti / 48 + Nb / 93-C / 12-N / 14] -0.01> 0 is satisfied.
After recrystallization annealing in a continuous annealing furnace,
In a nitriding atmosphere at a temperature of 00 ° C. or less, the product of the concentration of NH 3 (%) and the staying time (second) in this temperature range is 50 to 500, and the nitriding treatment is performed under a condition of 500 or less.
A method for producing a deep drawing BH steel sheet having excellent dent resistance and surface strain resistance, characterized by cooling at a temperature of 50 ° C / sec or more and 100 ° C / sec or less.
％以上、かつ 55｛Ｔｉ／48＋Ｎｂ／93−Ｃ／12−Ｎ／14]-0.01>0なる
条件を満足し、 残部Ｆｅおよび不可避的不純物からなる鋼を、冷延後、
連続焼鈍炉内で再結晶焼鈍をした後、６００℃以上、８
００℃以下の窒化雰囲気でＮＨ3 の濃度（％）とこの温
度域での滞在時間（秒）の積が５０以上、５００以下の
条件で窒化処理をし、その後５００℃までの平均冷速を
５０℃/sec以上、１００℃/sec以下で冷却することを特
徴とする耐デント性ならびに耐面ひずみ性に優れた深絞
り用ＢＨ鋼板の製造方法。2. C: 0.005% or less, N: 0.01% or less, Mn: 1.5% or less, Si: 1.0% or less, P: 0.1% or less, B: B: 0.0002% or more, 0.002% or less, Al: 0.005% or more, 0.2% or less, S: 0.02% or less, and either or both of Ti and Nb in a total amount of 0.02%
% Or more, and the condition of 55 ° Ti / 48 + Nb / 93-C / 12-N / 14] -0.01> 0 is satisfied.
After recrystallization annealing in a continuous annealing furnace,
In a nitriding atmosphere at a temperature of 00 ° C. or less, the product of the concentration of NH 3 (%) and the staying time (second) in this temperature range is 50 to 500, and the nitriding treatment is performed under a condition of 500 or less.
A method for producing a deep drawing BH steel sheet having excellent dent resistance and surface strain resistance, characterized by cooling at a temperature of 50 ° C / sec or more and 100 ° C / sec or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00063194A JP3311457B2 (en) | 1994-01-07 | 1994-01-07 | Method for producing BH steel sheet for deep drawing excellent in dent resistance and surface distortion resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00063194A JP3311457B2 (en) | 1994-01-07 | 1994-01-07 | Method for producing BH steel sheet for deep drawing excellent in dent resistance and surface distortion resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07197233A JPH07197233A (en) | 1995-08-01 |
| JP3311457B2 true JP3311457B2 (en) | 2002-08-05 |
Family
ID=11479084
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP00063194A Expired - Fee Related JP3311457B2 (en) | 1994-01-07 | 1994-01-07 | Method for producing BH steel sheet for deep drawing excellent in dent resistance and surface distortion resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3311457B2 (en) |
-
1994
- 1994-01-07 JP JP00063194A patent/JP3311457B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH07197233A (en) | 1995-08-01 |
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