JPH03199344A - Galvanized steel sheet for deep drawing having excellent continuous denting property and secondary operation resistant brittleness resistance - Google Patents
Galvanized steel sheet for deep drawing having excellent continuous denting property and secondary operation resistant brittleness resistanceInfo
- Publication number
- JPH03199344A JPH03199344A JP33975489A JP33975489A JPH03199344A JP H03199344 A JPH03199344 A JP H03199344A JP 33975489 A JP33975489 A JP 33975489A JP 33975489 A JP33975489 A JP 33975489A JP H03199344 A JPH03199344 A JP H03199344A
- Authority
- JP
- Japan
- Prior art keywords
- steel sheet
- less
- annealing
- deep drawing
- carbon concentration
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 229910001335 Galvanized steel Inorganic materials 0.000 title claims abstract description 19
- 239000008397 galvanized steel Substances 0.000 title claims abstract description 19
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 42
- 239000010959 steel Substances 0.000 claims abstract description 42
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 35
- 238000000137 annealing Methods 0.000 claims abstract description 28
- 239000010960 cold rolled steel Substances 0.000 claims abstract description 19
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 11
- 238000009826 distribution Methods 0.000 claims abstract description 9
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 7
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 6
- 238000005246 galvanizing Methods 0.000 claims abstract description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 29
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 20
- 229910052725 zinc Inorganic materials 0.000 claims description 20
- 239000011701 zinc Substances 0.000 claims description 20
- 238000007747 plating Methods 0.000 claims description 18
- 239000012535 impurity Substances 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 239000002245 particle Substances 0.000 claims 1
- 229910052748 manganese Inorganic materials 0.000 abstract description 3
- 230000001105 regulatory effect Effects 0.000 abstract 1
- 238000000034 method Methods 0.000 description 11
- 238000003466 welding Methods 0.000 description 9
- 238000005255 carburizing Methods 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 239000002344 surface layer Substances 0.000 description 6
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000002791 soaking Methods 0.000 description 4
- 238000001816 cooling Methods 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 238000005728 strengthening Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910000881 Cu alloy Inorganic materials 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910001297 Zn alloy Inorganic materials 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 239000002335 surface treatment layer Substances 0.000 description 1
Landscapes
- Heat Treatment Of Strip Materials And Filament Materials (AREA)
- Coating With Molten Metal (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
【発明の詳細な説明】
〈産業上の利用分野〉
本発明は、極低炭素鋼板の好ましくは連続焼鈍によって
製造される連続打点性および第２次加工脆性に優れた深
絞り用亜鉛系めっき鋼板に関する。[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a zinc-based galvanized steel sheet for deep drawing, which is produced by preferably continuous annealing of an ultra-low carbon steel sheet and has excellent continuous dotting properties and secondary work brittleness. Regarding.
〈従来の技術〉
近年、冷延鋼板の焼鈍法は、省エネルギーあるいは納期
短縮などを目的として連続焼鈍法（以下ＣＡＬ）が広く
取り入れられている。<Prior Art> In recent years, a continuous annealing method (hereinafter referred to as CAL) has been widely adopted as an annealing method for cold-rolled steel sheets for the purpose of saving energy or shortening delivery times.
ＣＡＬ焼鈍によりＹ値が高い深絞り性に優れた冷延鋼板
を得るには鋼中のＣ，Ｎの含量を極限にまで低減し、鋼
中の固溶Ｃや固溶Ｎを減少させることが有効であること
が知られている。In order to obtain a cold-rolled steel sheet with a high Y value and excellent deep drawability through CAL annealing, it is necessary to reduce the content of C and N in the steel to the utmost limit, and to reduce the amount of solid solute C and N in the steel. known to be effective.
最近の製鋼技術の進歩はめざましく、炭素、窒素を極限
にまで低減することが工業的にも可能となった今日、極
低炭素、あるいはセミ極低炭素ＣＡＬ焼鈍による深絞り
冷延鋼板を母板とする亜鉛系めっき鋼板の製造は従来の
低炭素箱焼鈍はよる製造に代わって急速に広がりつつあ
る。Recent advances in steelmaking technology have been remarkable, and today it has become industrially possible to reduce carbon and nitrogen to the utmost limit.Nowadays, deep-drawn cold-rolled steel sheets by ultra-low carbon or semi-ultra-low carbon CAL annealing are used as base plates. The production of galvanized steel sheets is rapidly replacing the conventional low carbon box annealing process.
この結果、製造された亜鉛系めっき鋼板は伸び、Ｔ値に
優れた深絞り成形じ適した特性を具備することが可能と
なった。 しかし、このような方法で製造された亜鉛
系めっき鋼板の原板の表面性状は、非常に成分元素の濃
化あるいは析出物が少ない粒界を呈しているため粒界が
弱く、脆化しやすいことが問題となる場合がある。 特
により絞り成形の厳しい部分にこの種表面処理鋼板が使
用される場合、粒界強度が弱い極低炭素鋼板を母板とす
る亜鉛めっき鋼板は２次加工性が問題となる場合があっ
た。 また亜鉛系めっき鋼板では、スポット溶接時に、
電極である銅合金と表面の亜鉛が合金化し、できた低融
点金属が母板の粒界に侵入して電極の消耗を早めるとい
う問題があった。 従来この対策を多くの研究者が検討
し、これまでにもその成果が開示されている。As a result, the manufactured zinc-based plated steel sheet has properties suitable for deep drawing, such as elongation and excellent T value. However, the surface properties of the raw zinc-plated steel sheets manufactured by this method exhibit very concentrated elemental elements or grain boundaries with few precipitates, making the grain boundaries weak and prone to embrittlement. This may be a problem. Particularly when this kind of surface-treated steel sheet is used in areas where drawing is more severe, galvanized steel sheets whose base plates are ultra-low carbon steel sheets with weak grain boundary strength may have problems in secondary workability. In addition, when spot welding galvanized steel sheets,
There was a problem in that the copper alloy that was the electrode and the zinc on the surface formed an alloy, and the resulting low-melting metal entered the grain boundaries of the mother plate, accelerating the wear of the electrode. Many researchers have previously considered this countermeasure, and their results have been disclosed so far.
たとえば、原板である冷延鋼板の表面にめっきを施す方
法があるが、そのいずれもが原板表面の特性に関する問
題を本質的に解決するような技術はまだ開示されていな
い。For example, there are methods for applying plating to the surface of a cold-rolled steel sheet, which is an original plate, but none of these techniques has yet disclosed a technique that essentially solves the problems regarding the characteristics of the original plate surface.
〈発明が解決しようとする課題〉
従来技術においても亜鉛めっき層に何らかの対策を施す
ことを開示されているが、原板となる冷延鋼板の表面、
すなわち、めっき界面での問題点を本質的に解決すると
ころまではいたっておらず、その多くはそのための製造
工程が加わるとともに、その効果は、表面特性の中でも
亜鉛めっき鋼板の化成処理性のみに着目したものであり
、その他の特性については何ら言及していない。 特に
スポット溶接時の連続打点性は大きな問題であったが、
実質的に解決する方法はこれまで開示されていない。<Problems to be Solved by the Invention> Although the prior art discloses that some measures are taken for the galvanized layer,
In other words, it has not yet reached the point where the problems at the plating interface have been essentially solved, and many of them require additional manufacturing processes, and the effects are only focused on the chemical conversion treatment properties of galvanized steel sheets among the surface properties. It does not mention any other characteristics. In particular, continuous dot performance during spot welding was a big problem.
No method to substantially solve this problem has been disclosed so far.
本発明は、前記亜鉛めっき鋼板の諸問題を解決するため
、その母板となる極低炭素冷延鋼板の焼鈍材の表面に関
する問題点を木質的に解決し、しかも、原板としての極
低炭素冷延鋼板の伸び、Ｔ値等優れた特性はそのまま生
かした連続打点性および第２次加工脆性に優れた深絞り
用亜鉛系めっき鋼板を提供することを目的とする。In order to solve the various problems of the galvanized steel sheet, the present invention solves the problems regarding the surface of the annealed material of the ultra-low carbon cold-rolled steel sheet that is the base plate, and also The object of the present invention is to provide a zinc-based galvanized steel sheet for deep drawing that is excellent in continuous dot performance and secondary work brittleness while taking advantage of the excellent properties of cold-rolled steel sheets such as elongation and T value.
く課題を解決するための手段〉
すなわち、本発明は、Ｃ： ０．００５ ｗｔ％以下、
Ｓ ｉ ： １．０ｗｔ％以下、Ｍ ｎ ： １．０ｗ
ｔ％以下、Ｐ ： ０．２ ｗｔ％以下、Ｓ ： ０．
（１５ｗｔ％以下、Ａｌ二０．０１〜０．１０ｗＬ％お
よびＮ ： ０．００５ ＊ｔ％以下を含み、残部はＦ
ｅおよび不可避的不純物よりなる冷延鋼板に焼鈍を施し
、その焼鈍後の板厚方向での炭素濃度分布が鋼板の表面
より１フェライト平均粒径に相当する厚さの層において
、平均炭素濃度が０．００５ ｗｔ％以上、０．１ ｗ
ｔ％以下であり、その最大炭素濃度が０．０１ｗｔ％以
上、０．２ｗｔ％以下である焼鈍板の両面あるいは片面
に亜鉛系めっきを有することを特徴とする連続打点性お
よび耐２次加工脆性に優れた深絞り用亜鉛系めっき鋼板
を提供する。Means for Solving the Problem> That is, the present invention provides C: 0.005 wt% or less,
Si: 1.0wt% or less, Mn: 1.0w
t% or less, P: 0.2 wt% or less, S: 0.
(Contains 15wt% or less, Al2 0.01-0.10wL% and N: 0.005*t% or less, the remainder is F
A cold-rolled steel sheet consisting of E and unavoidable impurities is annealed, and the carbon concentration distribution in the sheet thickness direction after annealing is such that the average carbon concentration is 0.005 wt% or more, 0.1 w
t% or less, and the maximum carbon concentration is 0.01wt% or more and 0.2wt% or less, and has zinc-based plating on both or one side of the annealed plate. To provide a galvanized steel sheet for deep drawing with excellent properties.
本発明はまた、Ｃ： ０．００５ ｗｔ％以下、Ｓｌ：
１、０ｗｔ％以下、Ｍ ｎ ： １．０ｗｔ％以下、Ｐ
： ０．２ｗｔ％以下、Ｓ ： ０．０５ｗｔ％以下
、ＡＩＬ：０．０１〜０ 、１０ｗｔ％およびＮ ：
０．００５ ｗｔ％以下を含みかつ
Ｔ ｉ ： ０．００１〜０．１５ｗｔ％およびＮ ｂ
： ０．００１〜０．１ ｗｔ％のうちから選んだ１
種または２種を含有し、残部はＦｅおよび不可避的不純
物よりなる冷延鋼板に焼鈍を施し、その焼鈍後の板厚方
向での炭素濃度分布が鋼板の表面より１フェライト平均
粒径に相当する厚さの層において、平均炭素濃度が０．
００５ ｗｔ％以上、０．１ ｗｔ％以下であり、その
最大炭素濃度が０．０１ｗｔ％以上、０．２ ｗｔ％以
下である焼鈍板の両面あるいは片面に亜鉛系めっきを有
することを特徴とする連続打点性および耐２次加工脆性
に優れた深絞り用亜鉛系めっき鋼板を提供する。The present invention also provides C: 0.005 wt% or less, Sl:
1.0 wt% or less, M n : 1.0 wt% or less, P
: 0.2wt% or less, S: 0.05wt% or less, AIL: 0.01-0, 10wt% and N:
0.005 wt% or less, T i : 0.001 to 0.15 wt% and N b
: 1 selected from 0.001 to 0.1 wt%
A cold-rolled steel sheet containing one or two types, with the remainder consisting of Fe and unavoidable impurities, is annealed, and the carbon concentration distribution in the thickness direction after annealing corresponds to one ferrite average grain size from the surface of the steel sheet. When the average carbon concentration is 0.
005 wt% or more and 0.1 wt% or less, and the maximum carbon concentration is 0.01 wt% or more and 0.2 wt% or less, and is characterized by having zinc-based plating on both or one side of the annealed plate. Provided is a galvanized steel sheet for deep drawing that has excellent continuous dotting properties and resistance to secondary work brittleness.
上記発明において、焼鈍を連続焼鈍および連続溶融亜鉛
めっき設備で行なうのが好ましい。In the above invention, it is preferable that the annealing be performed in a continuous annealing and continuous hot-dip galvanizing facility.
以下に本発明をさらに詳細に説明する。The present invention will be explained in more detail below.
本発明において用いる極低炭素鋼板は上記の組成を有す
るものがよい。 これを焼鈍、好ましくは連続焼鈍して
鋼板の両面における表層の炭素含有量を特徴とする特性
に適合するように調整する。 連続焼鈍によらない方法
としては、Ｃリッチｔｔ Ｆ ｅめっきを鋼板に施し、
焼鈍によりＣを拡散させる方法、あるいは製鋼段階で表
面にＣを濃化させた連続鋳造スラブを製造するなどの方
法により所期の目的を達するようにしてもよい。The ultra-low carbon steel plate used in the present invention preferably has the above composition. This is annealed, preferably continuously annealed, to adjust the carbon content of the surface layer on both sides of the steel plate to suit the characteristics. As a method that does not involve continuous annealing, C-rich tt Fe plating is applied to the steel plate,
The desired purpose may be achieved by diffusing C through annealing, or by manufacturing a continuously cast slab whose surface is enriched with C during steel manufacturing.
本発明の鋼板は、焼鈍、好ましくは連続焼鈍により冷延
鋼板表層部の炭素濃度を後述するように調整した焼鈍板
の両面または片面に亜鉛系めっきを有する。 亜鉛系め
っきとは亜鉛めっきはもとより、Ｚｎ−ＮＬ、Ｚｎ−Ｆ
ｅなどの亜鉛を主体とする合金めっき、溶融亜鉛合金化
めっきなどを広く含むものである。 さらに、必要に応
じてＦｅ−Ｐめっき等の第２層めっきを施してもよい。The steel sheet of the present invention has zinc-based plating on both or one side of the annealed sheet whose carbon concentration in the surface layer of the cold rolled steel sheet has been adjusted as described below by annealing, preferably continuous annealing. Zinc-based plating includes not only zinc plating but also Zn-NL, Zn-F
It broadly includes alloy plating mainly composed of zinc such as e, hot-dip zinc alloy plating, etc. Furthermore, a second layer plating such as Fe-P plating may be applied if necessary.
まず、焼鈍好ましくは連続焼鈍法により、深絞り性に優
れた鋼板を製造するには、Ｃ９Ｎの量は可能な限り少な
い方が好ましく、Ｃ：０．００５ ｗｔ％以下、Ｎ ：
０．００５ ｗｔ％以下とする必要がある。First, in order to produce a steel plate with excellent deep drawability by annealing, preferably by continuous annealing, the amount of C9N is preferably as small as possible, C: 0.005 wt% or less, N:
It needs to be 0.005 wt% or less.
Ｓｔは鋼を強化する作用があり、所望の強度に応じて必
要量添加されるが、添加量が１．０ｗｔ％を越えると深
絞り性に悪影響を及ぼすので１、０ｗｔ％以下と限定す
る。St has the effect of strengthening steel, and is added in a necessary amount depending on the desired strength. However, if the amount added exceeds 1.0 wt%, it will have a negative effect on deep drawability, so it is limited to 1.0 wt% or less.
ＭｎもＳｔと同様、鋼を強化する作用があり、所望の強
度に応じて必要量添加されるが、添加量が１．０ｗｔ％
を越えるとやはり深絞り性に悪影響を及ぼすので１．０
ｗｔ％以下に限定する。Like St, Mn also has the effect of strengthening steel, and is added in the required amount depending on the desired strength, but the amount added is 1.0 wt%.
If it exceeds 1.0, it will have a negative effect on deep drawability.
Limited to wt% or less.
ＰもＳｔやＭｎと同様、鋼を強化する作用があり、所望
の強度に応じて必要量添加されるが、添加量が０．２
ｗｔ％を越えると深絞り性に悪影響を及ぼすので０．２
ｗｔ％以下に限定する。Like St and Mn, P also has the effect of strengthening steel, and is added in the required amount depending on the desired strength.
If it exceeds wt%, it will have a negative effect on deep drawability, so 0.2
Limited to wt% or less.
Ｓは、少なければ少ないほど深絞り性が向上するので極
力低減することが好ましいが、その含有量が０．０５ｗ
ｔ％以下ではさほど悪影響を及ぼさないので０．０５ｗ
ｔ％以下に限定する。It is preferable to reduce S as much as possible because the smaller the amount, the better the deep drawability is.
If it is less than t%, it will not have much negative effect, so 0.05w
Limited to t% or less.
ＡＪ２は脱酸剤として、また後述する炭窒化物形成元素
の歩留まり向上のために添加されるが、含有量が０．０
１０ ｗｔ％に満たないとその添加効果に乏しく、一方
０．１０ｗｔ％を越えて添加してもその効果は飽和に達
するので、 ０．０１０〜０．１０ｗｔ％の範囲に限定
する。AJ2 is added as a deoxidizing agent and to improve the yield of carbonitride-forming elements, which will be described later.
If the amount is less than 10 wt%, the effect of addition is poor, and if it is added in excess of 0.10 wt%, the effect reaches saturation, so it is limited to a range of 0.010 to 0.10 wt%.
さらに、本発明で用いる冷延鋼板には、Ｔｉおよび／ま
たはＮｂを下記の通り添加してもよい。Furthermore, Ti and/or Nb may be added to the cold rolled steel sheet used in the present invention as described below.
Ｔｉは炭窒化物形成元素であり、鋼中の固溶（Ｃ，Ｎ）
を低減させ、深絞り性に有利な（１１１）方位を優先的
に形成させるために添加される。 しかしながら添加量
が０．００１ ｗｔ％未満ではその添加効果に乏しく、
一方０．ｆ５ｗｔ％を越えて添加してもそれ以上の効果
は得られず、むしろ鋼板表面性状および延性の劣化につ
ながるので０．００１〜０．１５ｗｔ％の範囲に限定す
る。Ti is a carbonitride forming element and is a solid solution (C, N) in steel.
is added to preferentially form the (111) orientation, which is advantageous for deep drawability. However, if the amount added is less than 0.001 wt%, the addition effect is poor,
On the other hand, 0. If f exceeds 5 wt%, no further effect can be obtained, and rather leads to deterioration of the steel sheet surface properties and ductility, so it is limited to a range of 0.001 to 0.15 wt%.
Ｎｂは炭化物形成元素であり、鋼中の固溶Ｃを低減させ
るとともに、熱延鋼板組織の微細化をそくして、深絞り
性に有利な（１１１）方位を優先的に形成させるために
添加される。 しかしながら添加量が０．００１ ｗｔ
％未満ではその添加の効果が乏しく、一方０．１ ｗｔ
％を越えて添加してもそれ以上の効果は得られず、むし
ろ延性の劣化につながるので０．００１〜０．１ ｗｔ
％の範囲に限定する。Nb is a carbide-forming element, and is added to reduce solid solution C in steel, prevent refinement of the hot-rolled steel sheet structure, and preferentially form the (111) orientation, which is advantageous for deep drawability. Ru. However, the amount added is 0.001 wt.
%, the effect of its addition is poor, while 0.1 wt.
If added in excess of 0.001 to 0.1 wt, no further effect will be obtained and it will actually lead to deterioration of ductility.
% range.
以上の限定範囲内の成分元素および不可避的不純物より
なる成分の冷延鋼板を焼鈍した後、亜鉛系めっきを施す
。 このとき、その連続焼鈍後の板厚方向での炭素濃度
分布を以下に述べるように制御すると、連続打点性およ
び耐２次加工脆性に優れた深絞り用亜鉛系めっき鋼板が
得られる。After annealing a cold-rolled steel sheet whose composition consists of component elements and unavoidable impurities within the above-mentioned limited ranges, zinc-based plating is applied. At this time, if the carbon concentration distribution in the sheet thickness direction after continuous annealing is controlled as described below, a zinc-based galvanized steel sheet for deep drawing with excellent continuous dotting properties and secondary work brittleness resistance can be obtained.
鋼板の高い伸び、高ｉ値等の優れた特性は上記成分鋼に
適切なＣＡＬ焼鈍あるいはＣＧＬ焼鈍を施すことによっ
て達成される。 このような鋼板をめっき原板として
製造した亜鉛系めっき（溶融、電気めっき）ｗ７４板は
優れた鋼板特性を有するため、深絞り用の亜鉛系めっき
鋼板として適する。 しかし、この優れた特性を実際
の自動車用あるいは一般部品用亜鉛系めっき鋼板として
使用するためには、成形後の組み立て工程で付加される
接合においても問題が生じないことが不可決である。
さらに、最終的な成形部品となった時に２次加工脆性が
問題となってもいけない。 もしもこのような問題が生
じれば、自動車用の表面処理鋼板としては重大な問題で
ある。Excellent properties such as high elongation and high i value of the steel plate can be achieved by subjecting the above component steel to appropriate CAL annealing or CGL annealing. A zinc-based plated (hot-dip, electroplated) W74 sheet manufactured using such a steel sheet as a plating original sheet has excellent steel sheet properties and is therefore suitable as a zinc-based plated steel sheet for deep drawing. However, in order to use this excellent property as a galvanized steel sheet for actual automobiles or general parts, it is essential that no problems occur in the joints added during the assembly process after forming.
Furthermore, secondary processing brittleness must not become a problem when the final molded part is produced. If such a problem were to occur, it would be a serious problem for surface-treated steel sheets for automobiles.
極低炭素鋼板を原板とした表面処理鋼板においては原板
の表面性状、特に粒界の性状が本質的に従来の低炭素箱
焼鈍材とは異なり、非常に成分元素の濃化あるいは析出
物の少ない粒界をていしているため粒界か弱く、脆化し
やすいことが問題となる場合がある。In surface-treated steel sheets using ultra-low carbon steel sheets as base plates, the surface properties of the base plates, especially the properties of grain boundaries, are essentially different from conventional low carbon box annealed materials, resulting in extremely high concentration of component elements and low precipitates. Since the grain boundaries are blocked, the grain boundaries are weak and easily become brittle, which can be a problem.
上記の表面処理（亜鉛系めっき）鋼板の接合工程におけ
るスポット溶接連続打点性においても電極である。銅合
金と表面処理層として存在していた亜鉛がスポット溶接
時に合金化し、形成した低融点金属（Ｃｎ−ｚｎ）が母
板の粒界に侵入して電極の消耗を早めるという問題点が
あった。 また、より絞り成形の厳しい部分にこの種表
面処理鋼板が使用される場合、粒界強度が弱い極低炭素
鋼板を母板とする亜鉛系めっき鋼板は２次加工脆性が問
題となる場合があった。It is also used as an electrode for continuous spot welding in the process of joining surface-treated (zinc-based plated) steel sheets. There was a problem that the copper alloy and zinc that existed as a surface treatment layer were alloyed during spot welding, and the formed low melting point metal (Cn-zn) invaded the grain boundaries of the base plate, accelerating the wear of the electrode. . Additionally, when this type of surface-treated steel sheet is used in areas that require more severe drawing, secondary work brittleness may become a problem with zinc-plated steel sheets whose base plates are ultra-low carbon steel sheets with weak grain boundary strength. Ta.
これら問題点は、めっき原板として使用していた箱焼鈍
材と比較して、表面層の化学的組成および析出物分布に
おいて差があることに起因している。 本発明は、この
ような従来低炭素箱焼鈍材において優れていた表面に関
わる特性を極低炭素ＣＡＬ焼鈍材においても達成するた
めの技術を開示するものであり、そのために、鋼板の表
面層における炭素濃度分布を規定している。These problems are due to differences in the chemical composition and precipitate distribution of the surface layer compared to the box-annealed material used as the original plate. The present invention discloses a technology for achieving surface-related properties that were excellent in conventional low-carbon box-annealed materials even in ultra-low-carbon CAL annealed materials. It defines the carbon concentration distribution.
即ち、表面処理（亜鉛系めっき＞ｖｉ４板の母板（焼鈍
冷延鋼板）表面１フェライト平均粒径に相当する厚さの
層における炭素濃度がその平均値で０．００５ ｗｔ％
以上、０．１ｗｔ％以下であり、その最大炭素濃度がＱ
、０１ｗｔ％以上、０．２ ＊ｔ％以下であることを必
要とする。 なお、１フェライト平均粒径は通常的２０
〜３０μｍ程度である。That is, the average carbon concentration in a layer with a thickness corresponding to the average grain size of ferrite on the surface treatment (zinc-based plating>VI4 base plate (annealed cold rolled steel sheet)) is 0.005 wt%.
above, 0.1wt% or less, and the maximum carbon concentration is Q
, 01wt% or more and 0.2*t% or less. In addition, the average grain size of 1 ferrite is usually 20
It is about ~30 μm.
即ち、２次加工脆性および溶接金属脆化が原因で生じる
スポット溶接時の連続打点性の劣化を木質的に解決する
には、鋼板の表面層に炭素が濃化することが有効である
が、その範囲は鋼板の表面！フェライト平均粒径相当の
厚さが確保されれば十分であり、それ以上の厚さの炭素
濃度を高めることは、鋼板のｉ値、延性等特性を害する
ことになる。 また、プレス成形後もその効果を維持し
、組み立て後も所期の効果を発揮するためにはこの表面
層における炭素濃度を上記限定範囲下限以上にする必要
があり、上限を越える炭素濃度の濃縮は、めっき鋼板の
深絞り性に悪影響を及ぼす。In other words, enriching carbon in the surface layer of the steel plate is effective in solving the problem of continuous spot welding performance during spot welding caused by secondary work embrittlement and weld metal embrittlement. That range is the surface of the steel plate! It is sufficient to ensure a thickness equivalent to the average ferrite grain size, and increasing the carbon concentration beyond this thickness will impair the i-value, ductility, and other properties of the steel sheet. In addition, in order to maintain the effect after press forming and to exhibit the desired effect even after assembly, the carbon concentration in this surface layer must be at least the lower limit of the above limited range, and the concentration of carbon that exceeds the upper limit must be has a negative effect on the deep drawability of plated steel sheets.
本発明において好適に用いられるＣＡＬ（Ｃｏｎｔｉｎ
ｕｏｕｓ Ａｎｎｅａｌｉｎｇ Ｌｉｎｅ ）あ
るいはＣＧ Ｌ （Ｃｏｎｔｉｎｕｏｕｓ Ｇａｌｌｖ
ａｎｉｚｉｎｇ Ｌｉｎｅ）は加熱、均熱および冷却ゾ
ーンを有する。 浸炭を上記設備を用いて効率的に実施
するには、均熱ゾーン後期から冷却ゾーンにかけて浸炭
用雰囲気として、浸炭に適する条件にして行なうのが好
ましい。CAL (Contin) suitably used in the present invention
continuous annealing line) or CG L (Continuous Gallv)
anizing line) has heating, soaking and cooling zones. In order to carry out carburizing efficiently using the above-mentioned equipment, it is preferable to set the carburizing atmosphere from the latter half of the soaking zone to the cooling zone under conditions suitable for carburizing.
浸炭用ガス中はＣＯを適量添加したものを用いる。 そ
して、浸炭条件は適切に選定する。A suitable amount of CO is added to the carburizing gas. Then, carburizing conditions are selected appropriately.
〈実施例〉 次に本発明を実施例に基づいて具体的に説明する。<Example> Next, the present invention will be specifically explained based on examples.
（実施例）
表１に示す組成の鋼を溶製後、熱間圧延により板厚２．
８ｍｍの熱延板として、脱スケール後冷間圧延により板
厚０．７ｍｍの冷延板とした。(Example) After melting steel having the composition shown in Table 1, it was hot rolled to a thickness of 2.
A hot rolled sheet of 8 mm was descaled and then cold rolled to a cold rolled sheet of 0.7 mm in thickness.
加熱、均熱および冷却ゾーンを有するＣＡＬにおいて、
加熱ゾーンにて８１０℃に加熱後、灼熱ゾーン後期にて
、７５０℃から８００℃間の所定の温度で１０〜３０秒
間５％Ｈ−０．５−１．０％Ｃｏを含有する窒素雰囲気
中に置き浸炭させた後、直ちに冷却する場合のヒートサ
イクルをシミュレートした熱処理を施した。In a CAL with heating, soaking and cooling zones,
After heating to 810°C in the heating zone, in the latter half of the scorching zone, at a predetermined temperature between 750°C and 800°C for 10 to 30 seconds in a nitrogen atmosphere containing 5% H-0.5-1.0% Co. After carburizing the specimen, it was subjected to heat treatment simulating a heat cycle in which it was immediately cooled.
この場合の加熱温度、均熱時間およびＣポテンシャルを
変化させて鋼板表面での浸炭量を変化させた。 さらに
スキンバスを施した後亜鉛系めっきを施して表面特性調
査用のサンプルを製造した。In this case, the amount of carburization on the surface of the steel plate was changed by changing the heating temperature, soaking time, and C potential. Furthermore, after applying a skin bath, zinc-based plating was applied to produce samples for surface characteristic investigation.
なお、族２中、ＥＧは電気亜鉛めっきを両面とも２０３
７ｍ２施したものを、Ｇｌは両面とも４０ ｇ／ｍ２溶
融亜鉛めっきしたものを意味する。In addition, in Group 2, EG has electrogalvanized 203 on both sides.
7m2 galvanized, and Gl means hot-dip galvanized at 40 g/m2 on both sides.
表面特性としては、連続打点性および耐２次加工脆性を
調査した。As for the surface properties, continuous dotting property and resistance to secondary processing brittleness were investigated.
連続打点性は、Ｃｕ電極を用いてサンプルの亜鉛系めっ
き鋼板に連続的にスポット溶接を行ない、ナゲツトが形
成されなくなるまでの打点数で評価する。Continuous spot welding is evaluated by continuously performing spot welding on a sample zinc-plated steel plate using a Cu electrode, and counting the number of spots until no nuggets are formed.
耐２次加工脆性は、絞り比２．０でカップ加工した後の
脆化温度で評価する。The secondary work embrittlement resistance is evaluated by the embrittlement temperature after cup processing at a drawing ratio of 2.0.
表１にはＣＡＬ焼鈍後の鋼板表面層における炭素濃度を
、また表２にはそのスポット溶接試験結果、２次加工脆
化試験結果および引張特性をまとめて示す。Table 1 shows the carbon concentration in the surface layer of the steel sheet after CAL annealing, and Table 2 shows the spot welding test results, secondary work embrittlement test results, and tensile properties.
〈発明の効果〉
本発明によって、極低炭素ＣＡＬ材の優れた特性（高Ｅ
ｌ、高〒値）を使用した亜鉛めっき鋼板が製造可能であ
り、実際に自動車用鋼板などとして使用する場合に必要
となる、連続打点性および耐２次加工脆性なとめっき板
の表面特性にかかわる重要な特性についても本質的に解
決できた。<Effects of the Invention> The present invention improves the excellent properties (high E
It is possible to produce galvanized steel sheets using galvanized steel (1, high value), and the surface properties of the galvanized sheets such as continuous dot resistance and resistance to secondary processing brittleness, which are required when actually used as steel sheets for automobiles, etc. We were also able to essentially resolve the important characteristics involved.
Claims (3)
以下、Ｍｎ：１．０ｗｔ％以下、Ｐ：０．２ｗｔ％以下
、Ｓ：０．０５ｗｔ％以下、Ａｌ：０．０１〜０．１０
ｗｔ％およびＮ：０．００５ｗｔ％以下を含み、残部は
Ｆｅおよび不可避的不純物よりなる冷延鋼板に焼鈍を施
し、その焼鈍後の板厚方向での炭素濃度分布が鋼板の表
面より１フェライト平均粒径に相当する厚さの層におい
て、平均炭素濃度が０．００５ｗｔ％以上、０．１ｗｔ
％以下であり、その最大炭素濃度が０．０１ｗｔ％以上
、０．２ｗｔ％以下である冷延鋼板の両面あるいは片面
に亜鉛系めっきを有することを特徴とする連続打点性お
よび耐２次加工脆性に優れた深絞り用亜鉛系めっき鋼板
。(1) C: 0.005wt% or less, Si: 1.0wt%
Below, Mn: 1.0 wt% or less, P: 0.2 wt% or less, S: 0.05 wt% or less, Al: 0.01 to 0.10
wt% and N: 0.005 wt% or less, with the balance consisting of Fe and unavoidable impurities, and the carbon concentration distribution in the thickness direction after annealing is 1 ferrite average from the surface of the steel sheet. In a layer with a thickness corresponding to the particle size, the average carbon concentration is 0.005 wt% or more, 0.1 wt%
% or less, and the maximum carbon concentration is 0.01 wt% or more and 0.2 wt% or less, and has zinc-based plating on both or one side of the cold rolled steel sheet. A galvanized steel sheet for deep drawing with excellent properties.
以下、Ｍｎ：１．０ｗｔ％以下、Ｐ：０．２ｗｔ％以下
、Ｓ：０．０５ｗｔ％以下、Ａｌ：０．０１〜０．１０
ｗｔ％およびＮ：０．００５ｗｔ％以下を含みかつ Ｔｉ：０．００１〜０．１５ｗｔ％およびＮｂ：０．０
０１〜０．１ｗｔ％のうちから選んだ１種または２種を
含有し、残部はＦｅおよび不可避的不純物よりなる冷延
鋼板に焼鈍を施し、その焼鈍後の板厚方向での炭素濃度
分布が鋼板の表面より１フェライト平均粒径に相当する
厚さの層において、平均炭素濃度が０．００５ｗｔ％以
上、０．１ｗｔ％以下であり、その最大炭素濃度が０．
０１ｗｔ％以上、０．２ｗｔ％以下である冷延鋼板の両
面あるいは片面に亜鉛系めっきを有することを特徴とす
る連続打点性および耐２次加工脆性に優れた深絞り用亜
鉛系めっき鋼板。(2) C: 0.005wt% or less, Si: 1.0wt%
Below, Mn: 1.0 wt% or less, P: 0.2 wt% or less, S: 0.05 wt% or less, Al: 0.01 to 0.10
wt% and N: 0.005 wt% or less, and Ti: 0.001 to 0.15 wt% and Nb: 0.0
A cold-rolled steel plate containing one or two selected from 01 to 0.1 wt% with the remainder consisting of Fe and unavoidable impurities is annealed, and the carbon concentration distribution in the thickness direction after annealing is In a layer having a thickness equivalent to one ferrite average grain size from the surface of the steel sheet, the average carbon concentration is 0.005 wt% or more and 0.1 wt% or less, and the maximum carbon concentration is 0.005 wt% or more and 0.1 wt% or less.
1. A galvanized steel sheet for deep drawing with excellent continuous dotting properties and resistance to secondary work brittleness, characterized by having zinc plating on both or one side of the cold rolled steel sheet in an amount of 0.01 wt% or more and 0.2 wt% or less.
設備で施すことを特徴とする請求項１または２に記載の
連続打点性および第２次加工脆性に優れた深絞り用亜鉛
系めっき鋼板。(3) The galvanized steel sheet for deep drawing with excellent continuous dotting properties and secondary work brittleness according to claim 1 or 2, wherein the annealing is performed using continuous annealing or continuous hot-dip galvanizing equipment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33975489A JP2854054B2 (en) | 1989-12-28 | 1989-12-28 | Zinc-based galvanized steel sheet for deep drawing with excellent continuous hitting and secondary work brittleness resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33975489A JP2854054B2 (en) | 1989-12-28 | 1989-12-28 | Zinc-based galvanized steel sheet for deep drawing with excellent continuous hitting and secondary work brittleness resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03199344A true JPH03199344A (en) | 1991-08-30 |
| JP2854054B2 JP2854054B2 (en) | 1999-02-03 |
Family
ID=18330488
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP33975489A Expired - Fee Related JP2854054B2 (en) | 1989-12-28 | 1989-12-28 | Zinc-based galvanized steel sheet for deep drawing with excellent continuous hitting and secondary work brittleness resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2854054B2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0466647A (en) * | 1990-07-07 | 1992-03-03 | Kobe Steel Ltd | Hot-dip galvanized cold rolled steel sheet for deep drawing having galvanized film excellent in adhesion and its manufacture |
| WO1993011271A1 (en) * | 1991-12-06 | 1993-06-10 | Kawasaki Steel Corporation | Method of manufacturing molten zinc plated steel plates having few unplated portions |
| US6074493A (en) * | 1994-06-15 | 2000-06-13 | Kawasaki Steel Corporation | Method of continuously carburizing metal strip |
| JP2001073079A (en) * | 1999-07-05 | 2001-03-21 | Kawasaki Steel Corp | Extra-low carbon thin steel sheet for deep drawing and extra-low carbon thin steel sheet for deep drawing applied with galvanizing |
-
1989
- 1989-12-28 JP JP33975489A patent/JP2854054B2/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0466647A (en) * | 1990-07-07 | 1992-03-03 | Kobe Steel Ltd | Hot-dip galvanized cold rolled steel sheet for deep drawing having galvanized film excellent in adhesion and its manufacture |
| WO1993011271A1 (en) * | 1991-12-06 | 1993-06-10 | Kawasaki Steel Corporation | Method of manufacturing molten zinc plated steel plates having few unplated portions |
| US5433796A (en) * | 1991-12-06 | 1995-07-18 | Kawasaki Steel Corporation | Method for preparing galvanized steel strip having minimal uncoated defects |
| US6074493A (en) * | 1994-06-15 | 2000-06-13 | Kawasaki Steel Corporation | Method of continuously carburizing metal strip |
| JP2001073079A (en) * | 1999-07-05 | 2001-03-21 | Kawasaki Steel Corp | Extra-low carbon thin steel sheet for deep drawing and extra-low carbon thin steel sheet for deep drawing applied with galvanizing |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2854054B2 (en) | 1999-02-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8337643B2 (en) | Hot rolled dual phase steel sheet | |
| JP6501045B1 (en) | Hot pressed member, method for producing the same, cold rolled steel sheet for hot pressing, and method for producing the same | |
| CN110809631B (en) | Hot-pressed member, method for manufacturing same, cold-rolled steel sheet for hot pressing, and method for manufacturing same | |
| JP6503584B2 (en) | Method of manufacturing hot rolled steel sheet, method of manufacturing cold rolled full hard steel sheet, and method of manufacturing heat treated sheet | |
| WO2019003449A1 (en) | Hot-pressed member and method for manufacturing same, and cold-rolled steel sheet for hot pressing | |
| JPH10130782A (en) | Ultrahigh strength cold rolled steel sheet and its production | |
| KR101482345B1 (en) | High strength hot-rolled steel sheet, hot-dip galvanized steel sheet using the same, alloyed hot-dip galvanized steel sheet using the same and method for manufacturing thereof | |
| JP4325998B2 (en) | High-strength hot-dip galvanized steel sheet with excellent spot weldability and material stability | |
| WO2019003542A1 (en) | Hot-pressed member and method for manufacturing same, and cold-rolled steel sheet for hot pressing and method for manufacturing same | |
| WO2019003538A1 (en) | Hot-pressed member and method for manufacturing same, and cold-rolled steel sheet for hot pressing and method for manufacturing same | |
| WO2020158285A1 (en) | Hot-pressed member, cold-rolled steel sheet for hot-pressed member, and methods respectively for producing these products | |
| US20220186339A1 (en) | Hot-pressed member, cold-rolled steel sheet for hot pressing, and manufacturing methods therefor | |
| JP2854054B2 (en) | Zinc-based galvanized steel sheet for deep drawing with excellent continuous hitting and secondary work brittleness resistance | |
| JP2005187837A (en) | High strength steel sheet for automobile fuel tank having excellent press moldability, corrosion resistance and secondary working properties, and its production method | |
| WO2019142559A1 (en) | High strength alloyed electrolytic zinc-plated steel sheet and method for producing same | |
| JP2802513B2 (en) | Method for producing steel sheet having excellent press formability, remarkable hardenability by heat treatment after molding and high corrosion resistance, and method for producing steel structural member using the steel sheet | |
| JP3142922B2 (en) | Manufacturing method of hot-rolled high-strength hot-dip galvanized steel sheet with low yield ratio and excellent pitting corrosion resistance | |
| JPH0832952B2 (en) | Manufacturing method of cold-rolled steel sheet for press work with excellent chemical conversion treatability, weldability, punchability and slidability | |
| JP3589416B2 (en) | Manufacturing method of ultra-low carbon hot-dip galvanized steel sheet for deep drawing with excellent fatigue properties | |
| JPH04346645A (en) | Production of high strength galvanized steel sheet excellent in bore expandability | |
| JP3408873B2 (en) | Manufacturing method of hot-dip galvanized steel sheet with excellent strength properties of spot welds | |
| JP2997489B2 (en) | Cold drawn steel sheet for deep drawing with excellent chemical conversion property and liquid metal brittle resistance | |
| JP2818675B2 (en) | Manufacturing method of surface-conditioned cold-rolled steel sheet | |
| JP2925616B2 (en) | Cold rolled steel sheet for processing with excellent punchability and its surface-treated steel sheet | |
| CN116815061A (en) | 780 MPa-grade low-spot-welding carbon equivalent alloyed galvanized dual-phase steel and preparation method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |