JPS61170541A - High strength hot rolled steel plate for wheel rim - Google Patents
High strength hot rolled steel plate for wheel rimInfo
- Publication number
- JPS61170541A JPS61170541A JP1119885A JP1119885A JPS61170541A JP S61170541 A JPS61170541 A JP S61170541A JP 1119885 A JP1119885 A JP 1119885A JP 1119885 A JP1119885 A JP 1119885A JP S61170541 A JPS61170541 A JP S61170541A
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- steel plate
- rolled steel
- hot rolled
- steel
- hardness
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Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明はホイールリム用高強度熱延鋼板に関し、詳しく
は、直流溶接性及び成形性にすぐれたホイールリム用高
強度熱延鋼板に関する。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a high-strength hot-rolled steel plate for wheel rims, and more particularly to a high-strength hot-rolled steel plate for wheel rims that has excellent DC weldability and formability.
（従来の技術）
自動車重量を軽減して燃料費を節減するために、車体を
小型化すると共に、高強度鋼材の採用による材料変更が
種々試みられている。特に、車輪の軽量化は燃料費の節
減に効果的であるとされニホイールリムに対する高強度
熱延鋼板の適用が鋭意研究されている。(Prior Art) In order to reduce the weight of automobiles and reduce fuel costs, various attempts have been made to reduce the size of automobile bodies and to change materials by using high-strength steel materials. In particular, it is believed that reducing the weight of wheels is effective in reducing fuel costs, and the application of high-strength hot-rolled steel sheets to two-wheel rims is being intensively studied.
ホイールリムは、従来、所定の幅及び長さに切断された
鋼板をリング状に成形し、端部を溶接した後、数工程の
ロールフォージングを経て製造されている。上記溶接に
は、従来、フラッシュバット溶接が採用されているが、
近年、フラッシュが飛ばないので、粉塵による作業環境
の劣化がないこと、騒音が生じないこと、更に、フラッ
シュで消耗する部分がないので、１％程度の歩留りの向
上を図り得ること等の理由から、直流溶接が採用される
傾向にある。Wheel rims have conventionally been manufactured by forming a steel plate cut into a predetermined width and length into a ring shape, welding the ends, and then performing several roll forging steps. Conventionally, flash butt welding is used for the above welding, but
In recent years, because the flash does not fly off, there is no deterioration of the working environment due to dust, no noise is generated, and since there are no parts that are consumed by the flash, it is possible to improve the yield by about 1%. , there is a tendency for direct current welding to be adopted.
しかし、ホイールリムの製造において、この直流溶接の
採用に伴う新しい問題が生じている。即ち、従来、引張
強さが４５ ｋｇｆ／＋＋ｕｓ”以下の鋼板を用いると
きには殆ど問題とされなかったが、Ｃ，、孕ユ、Ｍｎ量
が多い高強度鋼板を用いるとき、大電流による溶接、又
はアップセット過程中或いはアップセット後においても
通電するという溶接条件のために、溶接終了時点でオー
ステナイト粒が粗大化し、従って、冷却過程で焼入れ性
が高くなっているために、マルテンサイト又は硬質のベ
イナイトに変態しやすくなり、溶接部の硬度が非常に高
くなって、その結果、加工途中で溶接接合面から割れが
発生しやすい。この溶接部の硬度の最高値の限界は、従
来、何ら明確ではないが、本発明者らの研究によれば、
上限を３００程度とすることが好ましいところ、従来の
高張力鋼によれば、直流溶接材の溶接部の最高硬度（Ｈ
ｖ）は多くの場合、３００を越え、フラッシュバット溶
接材に比べて１００以上も高（、また、組織的にもマル
テンサイトに近い、更に、溶接部には脆性破面が存在し
、０℃におけるシャルピニ吸収エネルギー（ｖＥｏ）も
低い。However, new problems have arisen with the use of DC welding in wheel rim manufacturing. That is, when using a steel plate with a tensile strength of 45 kgf/++us'' or less, there was almost no problem in the past, but when using a high-strength steel plate with a large amount of C, Mn, welding with a large current, or Due to the welding conditions in which electricity is applied during or even after the upset process, austenite grains become coarse at the end of welding, and therefore have high hardenability during the cooling process, resulting in martensite or hard bainite grains. The hardness of the weld becomes very high, and as a result, cracks are likely to occur from the weld joint surface during processing.The maximum hardness limit of this weld has not been clearly defined in the past. However, according to the research of the present inventors,
It is preferable to set the upper limit to about 300, but according to conventional high-strength steel, the maximum hardness (H
v) in many cases exceeds 300, which is more than 100 higher than that of flash-butt welded materials. The Charpini absorbed energy (vEo) is also low.
（発明の目的）
このように、溶接部の硬度が高くなる原因は、直流溶接
はフラッシュバット溶接に比べて、大電流を流して溶接
する点にあるが、本発明者らは鋼材面からこの問題を解
決するために鋭意研究した結果、鋼に微量のＴｉ及びＮ
ｔ添加することにより、溶接時のオーステナイト粒の粗
大化が防止されると共に、微細に分散したＴｉＮがフェ
ライト粒の核発生サイトになるために、硬質のマルテン
サイトやベイナイトの生成が抑えられて、硬度上昇が防
止されることを見出して、本発明に至ったものである。(Purpose of the Invention) As described above, the reason why the hardness of the welded part increases is that DC welding uses a larger current to weld than flash butt welding. As a result of intensive research to solve the problem, trace amounts of Ti and N were found in the steel.
By adding t, coarsening of austenite grains during welding is prevented, and since the finely dispersed TiN becomes a nucleation site for ferrite grains, the formation of hard martensite and bainite is suppressed. The present invention was developed based on the discovery that the increase in hardness can be prevented.
（発明の構成）
本発明によるホイールリム用高強度熱延鋼板は、重量％
で
Ｇ ０．０５〜０．１５％、
Ｓｉ０．０５〜０．５％、
Ｍｎ １．０〜１．６％、
ＡｊＩ ０．Ｏ２Ｎ２．０５％、
Ｔｉ ０．００５〜０．０２５％、
Ｎ １５〜６０ｐｐ−を含有し、
Ｐ ０．０３０％以下、
Ｓ ０．０１０％以下に規制し、
残部鉄及び不可避的不純物よりなることを特徴とする。(Structure of the Invention) The high-strength hot-rolled steel sheet for wheel rims according to the present invention has a weight%
G 0.05-0.15%, Si 0.05-0.5%, Mn 1.0-1.6%, AjI 0. Contains 2.05% O2N, 0.005-0.025% Ti, 15-60pp- of N, and regulates P to 0.030% or less and S to 0.010% or less, with the remainder consisting of iron and unavoidable impurities. It is characterized by
本発明鋼における化学成分の限定理由について説明する
。The reason for limiting the chemical components in the steel of the present invention will be explained.
Ｃは、鋼に所要の強度を与えるために必要な元素であっ
て、少なくとも０．０５％の添加が必要である。一方、
直流溶接は、前記したように、溶接部の硬度を高める特
性を有しているから、Ｃを過多に添加することは好まし
くなく、本発明鋼においては、Ｃ添加量の上限を０．１
５％とする。C is an element necessary to give the steel the required strength, and must be added in an amount of at least 0.05%. on the other hand,
As mentioned above, direct current welding has the property of increasing the hardness of the welded part, so it is not preferable to add too much C. In the steel of the present invention, the upper limit of the amount of C added is set to 0.1.
5%.
Ｓｉは、溶接過程において突き合わせ面に生成するベネ
トレーターに影響し、ペネトレーターの生成を抑制する
ために、添加量を０．０５〜０．５％の範囲とする。こ
の範囲をはずれるとき、ベネトレーターが発生する。Si affects penetrators generated on the abutting surfaces during the welding process, and in order to suppress the production of penetrators, the amount added is in the range of 0.05 to 0.5%. When outside this range, a venetrator occurs.
Ｍｎは、鋼の強度を高めるために必要であり、５０ ｋ
ｇｆ／ａｍ”以上の引張強さを持つ高強度鋼板を得るた
めには、１．０％以上の添加が必要である。Mn is necessary to increase the strength of steel, and 50 k
In order to obtain a high-strength steel plate with a tensile strength of 1.0% or more, it is necessary to add 1.0% or more.
しかし、過多に添加するときは、第２相が層状に並んで
、所謂帯状組織が形成されやすく、この結果、特に幅方
向又は板厚方向の延性を劣化させるので、添加量の上限
を１．６％とする。However, if too much is added, the second phase is likely to line up in layers, forming a so-called band-like structure, and as a result, the ductility, especially in the width direction or thickness direction, is deteriorated, so the upper limit of the amount added is set at 1. 6%.
Ｐを過剰に含有させるときは、溶接部を劣化させるので
、含有量は０．０３％以下に規制する。When P is contained excessively, the welded part is deteriorated, so the content is regulated to 0.03% or less.
Ｓは、伸長したＭｎＳの量を増加させ、メタルフローに
沿った割れの原因となるので、その含有量はできる限り
低い方がよいが、実質的には０．０１％以下に規制すれ
ば十分である。S increases the amount of elongated MnS and causes cracks along the metal flow, so it is better to keep its content as low as possible, but in practice it is sufficient to limit it to 0.01% or less. It is.
Ａｎは、鋼の脱酸のために０．０１％以上の添加が必要
である。しかし、過多に添加するときは、アルミナ系介
在物を増加させ、ＭｎＳと同様にフック状割れの原因と
なるので、添加量の上限を０．０５％とする。It is necessary to add 0.01% or more of An to deoxidize the steel. However, when added in excess, it increases alumina-based inclusions and causes hook-like cracks like MnS, so the upper limit of the amount added is set at 0.05%.
Ｔｉは、溶接部の硬度を低下させるための必須の元素で
ある。微細なＴｉＮをできる限り多く分散させて、上記
効果を有効に得るには、添加量を０゜００５％以上とす
ることが必要であるが、他方、過多に添加するときは、
ＴｉＮが粗大化し、その数か減少して１、上記微細化に
よる溶接部の硬度を低める効果が減少するので、上限は
０．０２５％とする。Ti is an essential element for reducing the hardness of the weld. In order to disperse as much fine TiN as possible and effectively obtain the above effects, it is necessary to add an amount of 0°005% or more, but on the other hand, when adding too much,
The upper limit is set to 0.025% because TiN becomes coarser and its number decreases, which reduces the effect of reducing the hardness of the welded part due to the above-mentioned refinement.
Ｎは、微細なＴｉＮとして分散させて、フェライト粒の
核発生サイトとして硬質のマルテンサイトやベイナイト
の生成を抑制し、硬度上昇を防止するために有効であり
、含有量が１５ｐｐｍよりも少ないときはＴｉＮの生成
量が不十分であって、上記効果を有効に得ることができ
ない。しかし、含有量が６０ｐｐ＋ｍを越えるときは、
綱の延性や時効性が劣化する。従って、本発明鋼におい
ては、Ｎの含有量は１５〜６０ｐｐｍの範囲とする。N is dispersed as fine TiN to suppress the formation of hard martensite and bainite as nucleation sites of ferrite grains, and is effective in preventing an increase in hardness. When the content is less than 15 ppm, The amount of TiN produced is insufficient, and the above effects cannot be effectively obtained. However, when the content exceeds 60pp+m,
The ductility and aging properties of the rope deteriorate. Therefore, in the steel of the present invention, the N content is in the range of 15 to 60 ppm.
本発明鋼においては、上記した元素に加えて、Ｎｂを添
加することができる。Ｎｂは、析出強化によって鋼強度
を高める元素であり、この効果を有効に発現させるため
には、少なくとも０．０１％を添加することが必要であ
る。この強化効果は添加貴社比例するが、過多に添加す
ることは、他方で母材の延性劣化を招くので、添加量の
上限は０゜０６％とする。In the steel of the present invention, Nb can be added in addition to the above-mentioned elements. Nb is an element that increases steel strength through precipitation strengthening, and in order to effectively exhibit this effect, it is necessary to add at least 0.01%. This strengthening effect is proportional to the amount of addition, but adding too much leads to deterioration of the ductility of the base metal, so the upper limit of the addition amount is set at 0.06%.
更に、本発明鋼においては、上記したＮｂと共に、又は
それらとは別にＣａ及びＲＥＭよりなる群から選ばれる
少なくとも１種の元素を添加することができる。これら
元素は、伸長したＭｎＳを球状化させて、フック状割れ
の発生を防止するうえに効果的である。このような効果
を有効に得るには、Ｃａについては０．０００５％、Ｒ
ＥＭについては０．００５％以上の添加を必要とする。Furthermore, in the steel of the present invention, at least one element selected from the group consisting of Ca and REM can be added together with or separately from the above-mentioned Nb. These elements are effective in making the elongated MnS spheroidal and preventing the occurrence of hook-like cracks. In order to effectively obtain such effects, Ca should be set at 0.0005%, R
For EM, it is necessary to add 0.005% or more.
しかし、過多に添加しても、効果が飽和するのみならず
、溶接部にペネトレーターを生成し、これを起点とする
割れが発生しやすくなるので、添加量の上限は、Ｃａに
ついては０．０１％、ＲＥＭについては０．１％とする
。However, if too much Ca is added, the effect will not only be saturated, but also create a penetrator in the weld, making it more likely that cracks will start from this, so the upper limit of the amount added is 0.01 % and REM is 0.1%.
（発明の効果）
以上のように、本発明鋼は微量のＴｉと所定範囲のＮを
含有するので、溶接時のオーステナイト粒の粗大化が防
止されると共に、微細に分散したＴｉＮがフェライト粒
の核発生サイトになるために、硬質のマルテンサイトや
ベイナイトの生成が抑えられて、硬度上昇が有効に防止
される。従って、同じＣｅｑの比較鋼に比べて、溶接部
の最高硬度を著しく減じることができ、また、ｖＢ６も
フラッシュバット溶接材と同等の高い値を得ることがで
きる。(Effects of the Invention) As described above, since the steel of the present invention contains a small amount of Ti and a predetermined range of N, coarsening of austenite grains during welding is prevented, and finely dispersed TiN is added to ferrite grains. Since it becomes a nucleation site, the generation of hard martensite and bainite is suppressed, and an increase in hardness is effectively prevented. Therefore, compared to comparative steels of the same Ceq, the maximum hardness of the welded part can be significantly reduced, and vB6 can also be as high as the flash butt welded material.
（実施例）
実施例１
第１表に示す化学成分を有する鋼を真空溶解炉にて溶製
し、実験室的に熱間圧延を行ない、両面を切削して厚さ
２．６ Ｍの鋼板とした後、直流溶接又はフラッシュバ
ット溶接にて溶接し、溶接部の硬度を測定した。また、
２．５鶴幅ＪＩＳ４号シャルピー試験片による０℃での
シャルピー試験を行なった。結果を第１表、第１図及び
第２図に示す。(Example) Example 1 Steel having the chemical composition shown in Table 1 was melted in a vacuum melting furnace, hot rolled in a laboratory, and both sides were cut to form a steel plate with a thickness of 2.6 M. After that, welding was performed by direct current welding or flash butt welding, and the hardness of the welded part was measured. Also,
A Charpy test was conducted at 0° C. using a 2.5 width JIS No. 4 Charpy test piece. The results are shown in Table 1, Figures 1 and 2.
第１図はＣｅｑと直流溶接による溶接部の最高硬度（Ｈ
ｖ）の関係を示し、比較鋼は最高硬度が多くの場合、３
００を越える。比較鋼９及び１３のように、Ｃｅｑを低
減することによって、ある程度は最高硬度を減じること
ができるが、微量のＴｉを添加することによって初めて
、溶接部の最高硬度を大幅に減じることができる。第２
図は０℃におけるシャルピー吸収エネルギー（ｖｆ！ｏ
）を示し、最高硬度の高い直流溶接材では脆性破面が存
在するので、ｖＥ、が著しく低い。Figure 1 shows the maximum hardness (H
v), and the maximum hardness of comparative steels is often 3.
Over 00. As in Comparative Steels 9 and 13, the maximum hardness can be reduced to some extent by reducing Ceq, but only by adding a small amount of Ti can the maximum hardness of the weld zone be significantly reduced. Second
The figure shows the Charpy absorbed energy (vf!o
), and the DC welding material with the highest hardness has a brittle fracture surface, so vE is extremely low.
このように、本発明鋼によれば、同じＣｅｑの比較鋼に
比べて、溶接部の最高硬度を著しく減じることができ、
また、ｖＥｏもフラッシュバット溶接材と同等の高い値
を得ることができる。As described above, according to the steel of the present invention, the maximum hardness of the welded part can be significantly reduced compared to the comparative steel of the same Ceq.
Furthermore, a high vEo value equivalent to that of flash butt welded materials can be obtained.
実施例２
第２表に示す化学成分を有する鋼を転炉溶製し、通常の
工業的な製鉄法に従って、厚さ２．６ ｔｍの鋼板を製
造した。尚、゛熱間圧延は、８００〜８８０℃の温度で
仕上圧−し、４５０〜６５０℃の温度で巻取った。圧延
後の冷却は、化学成分に応じて７００℃前後で５〜１０
秒空冷し、その前後を急冷する制御冷却も行なった。Example 2 Steel having the chemical components shown in Table 2 was melted in a converter, and a steel plate with a thickness of 2.6 tm was manufactured according to a normal industrial iron manufacturing method. In the hot rolling, finishing pressure was applied at a temperature of 800 to 880°C, and coiling was performed at a temperature of 450 to 650°C. Cooling after rolling is performed at around 700℃ for 5 to 10 minutes depending on the chemical composition.
Controlled cooling was also performed in which air cooling was performed for a second and then the front and rear parts were rapidly cooled.
これらの鋼板をホイールリム製造ラインにおいて直流溶
接後、ホイールリムに成形し、製品不良率を測定した。After direct current welding, these steel plates were formed into wheel rims on a wheel rim manufacturing line, and the product defect rate was measured.
結果を第２表に示す。本発明鋼では、不良率が著しく小
さい。また、硬度分布を第３図に示す。本発明鋼によれ
ば、溶接部最高硬度が低く抑えられている。The results are shown in Table 2. The steel of the present invention has a significantly lower defective rate. Moreover, the hardness distribution is shown in FIG. According to the steel of the present invention, the maximum hardness of the welded part is kept low.
第１図は、本発明鋼及び比較鋼におけるＣｅｑと直流溶
接による溶接部の最高硬度（ＨＶ）の関係を示すグラフ
、第２図は、本発明鋼及び比較鋼の０℃におけるシャル
ピー吸収エネルギー（ｖ［！ｏ）を示すグラフ、第３図
は、本発明鋼及び比較鋼の溶接部の硬度分布の例を示す
グラフである。
特許出願人 株式会社神戸製鋼所
代理人 弁理士 牧 野 逸 部
第１図
炭素台１（ｏｌｏ）
第２図
炭素合量（％）
第３図Fig. 1 is a graph showing the relationship between Ceq and the maximum hardness (HV) of the welded part by direct current welding in the inventive steel and comparative steel, and Fig. 2 shows the Charpy absorbed energy (HV) at 0°C of the inventive steel and comparative steel. The graph showing v[!o) in FIG. 3 is a graph showing an example of the hardness distribution of the welded parts of the inventive steel and comparative steel. Patent Applicant Kobe Steel Co., Ltd. Representative Patent Attorney Ittsu Makino Department Figure 1 Carbon table 1 (olo) Figure 2 Total carbon content (%) Figure 3
Claims (3)
イールリム用高強度熱延鋼板。(1) C0.05-0.15%, Si0.05-0.5%, Mn1.0-1.6%, Al0.01-0.05%, Ti0.005-0.025% in weight% , N15 to 60 ppm, P 0.030% or less, S S 0.010% or less, and the balance is iron and unavoidable impurities.
イールリム用高強度熱延鋼板。(2) C0.05-0.15%, Si0.05-0.5%, Mn1.0-1.6%, Al0.01-0.05%, Ti0.005-0.025% in weight% , Nb 0.01~0.06%, N15~60ppm, P regulated to 0.030% or less, S 0.010% or less, and the balance is iron and inevitable impurities. High strength for wheel rims. Hot rolled steel plate.
イールリム用高強度熱延鋼板。(3) In weight% (a) C0.05-0.15%, Si0.05-0.5%, Mn1.0-1.6%, Al0.01-0.05%, Ti0.005-0 .025%, N15-60ppm, and (b) at least one selected from the group consisting of Ca0.0005-0.01% and REM0.005-0.1%, P0.030% or less, S0. A high-strength hot-rolled steel sheet for wheel rims, which is regulated to 0.010% or less, with the remainder consisting of iron and unavoidable impurities.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1119885A JPS61170541A (en) | 1985-01-24 | 1985-01-24 | High strength hot rolled steel plate for wheel rim |
| US07/087,967 US4880480A (en) | 1985-01-24 | 1987-08-17 | High strength hot rolled steel sheet for wheel rims |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1119885A JPS61170541A (en) | 1985-01-24 | 1985-01-24 | High strength hot rolled steel plate for wheel rim |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61170541A true JPS61170541A (en) | 1986-08-01 |
| JPH0575823B2 JPH0575823B2 (en) | 1993-10-21 |
Family
ID=11771341
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1119885A Granted JPS61170541A (en) | 1985-01-24 | 1985-01-24 | High strength hot rolled steel plate for wheel rim |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61170541A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6293346A (en) * | 1985-10-18 | 1987-04-28 | Nippon Steel Corp | High strength steel excellent in cod characteristics in weld zone |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5443822A (en) * | 1977-09-14 | 1979-04-06 | Nippon Steel Corp | Manufacture of high tensile hot rolled steel sheet with low intrafacial plastic anisotropy |
| JPS5488827A (en) * | 1977-12-26 | 1979-07-14 | Kawasaki Steel Co | Production of high tensile hot rolling steel plate with excellent extensibility and flanging property |
-
1985
- 1985-01-24 JP JP1119885A patent/JPS61170541A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5443822A (en) * | 1977-09-14 | 1979-04-06 | Nippon Steel Corp | Manufacture of high tensile hot rolled steel sheet with low intrafacial plastic anisotropy |
| JPS5488827A (en) * | 1977-12-26 | 1979-07-14 | Kawasaki Steel Co | Production of high tensile hot rolling steel plate with excellent extensibility and flanging property |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6293346A (en) * | 1985-10-18 | 1987-04-28 | Nippon Steel Corp | High strength steel excellent in cod characteristics in weld zone |
| JPH0414179B2 (en) * | 1985-10-18 | 1992-03-12 | Nippon Steel Corp |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0575823B2 (en) | 1993-10-21 |
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