JPH0428781B2 - - Google Patents
Info
- Publication number
- JPH0428781B2 JPH0428781B2 JP59061636A JP6163684A JPH0428781B2 JP H0428781 B2 JPH0428781 B2 JP H0428781B2 JP 59061636 A JP59061636 A JP 59061636A JP 6163684 A JP6163684 A JP 6163684A JP H0428781 B2 JPH0428781 B2 JP H0428781B2
- Authority
- JP
- Japan
- Prior art keywords
- bath
- hot
- aluminum
- dip
- added
- 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.)
- Expired - Lifetime
Links
- 239000007789 gas Substances 0.000 claims description 28
- 229910000831 Steel Inorganic materials 0.000 claims description 27
- 239000010959 steel Substances 0.000 claims description 27
- 238000007747 plating Methods 0.000 claims description 21
- 229910052782 aluminium Inorganic materials 0.000 claims description 17
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 15
- 210000004894 snout Anatomy 0.000 claims description 15
- 229910052746 lanthanum Inorganic materials 0.000 claims description 12
- 229910052684 Cerium Inorganic materials 0.000 claims description 10
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 229910052779 Neodymium Inorganic materials 0.000 claims description 6
- 230000002829 reductive effect Effects 0.000 claims description 6
- 229910052739 hydrogen Inorganic materials 0.000 claims description 4
- 229910052727 yttrium Inorganic materials 0.000 claims description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 3
- 229910052777 Praseodymium Inorganic materials 0.000 claims description 3
- 239000001257 hydrogen Substances 0.000 claims description 3
- 229910052761 rare earth metal Inorganic materials 0.000 description 24
- 230000007547 defect Effects 0.000 description 18
- 239000000203 mixture Substances 0.000 description 9
- 229910052751 metal Inorganic materials 0.000 description 8
- 239000002184 metal Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 6
- 238000000137 annealing Methods 0.000 description 5
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 5
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical group [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 5
- 229910052710 silicon Inorganic materials 0.000 description 5
- 229910000680 Aluminized steel Inorganic materials 0.000 description 4
- 229910001335 Galvanized steel Inorganic materials 0.000 description 4
- 229910000655 Killed steel Inorganic materials 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 239000008397 galvanized steel Substances 0.000 description 4
- 239000012535 impurity Substances 0.000 description 3
- 238000011835 investigation Methods 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 238000002845 discoloration Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- 229910021364 Al-Si alloy Inorganic materials 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 229910002056 binary alloy Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005246 galvanizing Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 230000001846 repelling effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
- C23C2/12—Aluminium or alloys based thereon
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Coating With Molten Metal (AREA)
Description
本発明はめつき性に優れた溶融アルミニウムめ
つき鋼板の製造方法に関する。
従来より溶融アルミニウムめつき鋼板は耐熱
性、耐食性の要求される分野に幅広く利用されて
いるが、これらの分野に使用するにあたつては通
常種類を分けている。一般に溶融アルミニウムめ
つき鋼板にはAl−Si合金浴に鋼板を浸漬してめ
つきしたアルミナイズド鋼１型と純Al浴に鋼板
を浸漬してめつきしたアルミナイズド鋼２型の２
種があるが、前者は鋼板に形成される脆いFe−
Al二元系合金属が浴中のSiにより抑制され、３
〜5μｍと薄くしか成長せず、加工性、耐熱性が
よいことから加工性や耐熱性を要求される分野に
使用され、後者は脆いFe−Al二元系合金属が20μ
ｍ程度まで厚く成長し、加工性が劣ることから加
工が軽度で耐食性を要求される分野に使用されて
いる。
従来これらの溶融アルミニウムめつき鋼板（以
下溶融Alめつき鋼板という）は工業的には溶融
亜鉛めつき鋼板と同様センジマータイプの連続溶
融めつきラインすなわち、まず前処理酸化帯にて
鋼板に付着した不純物を燃焼除去し、次に、還元
帯にて水素を含有する雰囲気ガスで還元した後、
同雰囲気ガスの充たされたダクト状のスナウトよ
り浴面が同雰囲気ガスに覆われたアルミニウム浴
に浸漬して、溶融めつきするインライン焼鈍方式
のラインで製造されているが、このラインで製造
する場合前処理還元帯に導入する雰囲気ガス
〔HNXガス（H2約11％）やHNXガスとAXガス
（H2約75％）との混合ガス〕の露点を溶融亜鉛め
つき鋼板の場合の−30〜−40℃より低くしないと
直径１mm以下のピンホール状めつきはじき、すな
わち点状不めつきが発生するという問題があつ
た。
第１表はこの点状不めつきの発生状況とスナウ
ト部雰囲気ガス露点との関係を示したもので、溶
融Alめつき鋼板の場合には溶融亜鉛めつき鋼板
の場合より露点を約30℃以上低くしないと点状不
めつき発生を完全に防止できない。
The present invention relates to a method for producing a hot-dip aluminum plated steel sheet with excellent plating properties. Conventionally, hot-dip aluminum plated steel sheets have been widely used in fields where heat resistance and corrosion resistance are required, but they are usually divided into different types when used in these fields. In general, there are two types of molten aluminum-plated steel sheets: Type 1 aluminized steel, in which the steel plate is immersed in an Al-Si alloy bath and plated, and Type 2 aluminized steel, in which the steel plate is plated by immersing it in a pure Al bath.
There are two types, but the former is a brittle Fe-
Al binary alloy is suppressed by Si in the bath, and 3
It grows only as thin as ~5μm and has good workability and heat resistance, so it is used in fields that require workability and heat resistance.
It grows to a thickness of about 1.5 m and has poor workability, so it is used in fields where light processing is required and corrosion resistance is required. Conventionally, these hot-dip aluminum-plated steel sheets (hereinafter referred to as hot-dip aluminum-plated steel sheets) are industrially manufactured using a Sendzimer-type continuous hot-dip galvanizing line, which is the same as hot-dip galvanized steel sheets, that is, they are first coated on the steel sheet in a pretreatment oxidation zone. After removing the impurities by burning, and then reducing with hydrogen-containing atmospheric gas in the reduction zone,
It is manufactured on an in-line annealing line in which the bath surface is immersed in an aluminum bath covered with the same atmospheric gas through a duct-shaped snout filled with the same atmospheric gas, and then melted and annealed. In the case of hot-dip galvanized steel sheets, the dew point of the atmospheric gas [HNX gas ( H2 approx. 11%) or mixed gas of HNX gas and AX gas ( H2 approx. 75%)] introduced into the pretreatment reduction zone should be If the temperature was not lowered to below -30 to -40°C, there was a problem in that pinhole-like plating repelling with a diameter of 1 mm or less, that is, point-like discoloration occurred. Table 1 shows the relationship between the occurrence of this point-like discoloration and the dew point of the atmospheric gas at the snout. If it is not lowered, it will not be possible to completely prevent the occurrence of spot defects.
【表】
なお第１表の点状不めつき発生状況調査は溶融
Alめつき鋼板、溶融亜鉛めつき鋼板とも同一め
つき原板〔C0.04、Si0.01、Mn0.28、P0.013、
S0.011、solAl0.015、残Fe（以上重量％）のアル
ミキルド鋼鋼板〕を用いて、これを750℃の
HNXガス雰囲気中で30秒還元焼鈍した後同雰囲
気下にある浴温680℃のAl−6.5％Si浴および浴温
460℃のZn−0.18％Al浴に３秒間浸漬してめつき
することにより得られた鋼板について行つたもの
である。めつき付着量はともに片面60ｇ／m2で、
点状不めつきの個数は大きさが50mm／100mmのサ
ンプル両面に発生した点状不めつきを目視により
計数したものである。
外観上点状不めつきが発生した場合、その個数
が５個／ｄm2以下ならば外観は良好であるが、５
個／ｄm2を越えると次第に外観も劣つてくる。こ
のため従来点状不めつきの個数を５個／ｄm2以下
にするためスナウト部の雰囲気ガス露点は−50℃
以下になるように管理していた。
しかしながらスナウト部の露点を−50℃以下に
するには前処理還元帯へ供給する雰囲気ガスの露
点を−60℃以下にしなければならず、また設備的
にも焼鈍や冷却炉などの接合部シーリングを厳重
にしなければならないので、管理が極めてむずか
しいものであつた。
本発明はこのような状況からスナウト部の雰囲
気ガス露点を極端に下げなくても点状不めつきの
発生しない溶融Alめつき鋼板の製造方法を提供
するものである。
前述の如く溶融Alめつき鋼板の点状不めつき
は前処理還元帯の雰囲気ガス露点をスナウト部に
おいて−50℃以下にすればある程度防止できるの
であるが、露点を下げることにより点状不めつき
が発生しなくなるのはスナウト部のめつき浴表面
に存在する酸化皮膜が少くなるためであることが
わかつている。すなわちAlはZnに比べて酸化さ
れやすく、融点も高いため、スナウト部の露点が
同一である場合めつき浴表面に酸化皮膜が形成さ
れやすい。このためスナウト部の露点が−30〜−
40℃である場合亜鉛浴では表面に酸化皮膜が著し
く形成されなくてもアルミニウム浴では著しく形
成されてしまい、鋼板がスナウトよりめつき浴に
侵入する際酸化皮膜を巻込んで点状不めつきが発
生するのである。従つてスナウト部の露点を低く
すればめつき浴表面に形成される酸化皮膜が少く
なり、点状不めつきは発生しなくなる。
しかしながらスナウト部の露点を−50℃以下に
するには前述の如き問題があるので、本発明者ら
は浴組成的にスナウト部の露点を極端に低くしな
くてもよい方法を検討したところ、めつき浴に希
土類元素を0.01〜1.0重量％添加すればよいこと
を見出したのである。そして種々の希土類元素に
ついてその効果を調査したところLa、Ce、Nd、
PrおよびＹが好ましく、またこれらの希土類元
素を２種以上添加してもその合計量が１種の場合
と同じであれば同等の効果を得ることができるこ
とが判明した。かくして本発明は鋼板を前処理還
元帯にて水素濃度11％以上の雰囲気ガスで還元し
た後、同雰囲気ガスの充たされたスナウトより浴
面が同雰囲気ガスに覆われたアルミニウム浴に浸
漬して溶融めつきするセンジマータイプの溶融め
つきラインにより溶融アルミニウムめつき鋼板を
製造する際、アルミニウムウ浴にLa、Ce、Nd、
Pr、Ｙのうち１種以上を0.01〜1.0重量％および
Siを０〜11重量％添加して溶融めつきすることを
特徴とする溶融Alめつき鋼板の製造方法を提供
するものである。
本発明においてめつき浴に添加する希土類元素
としては希土類元素単体のものを用いてもよい
が、希土類元素単体は高価であるので、工業的に
は安価であるミツシユメタル（天然組成のままの
混合希土類金属）を用いるのが有利である。ラン
タンミツシユメタルおよびセリウムミツシユメタ
ルについて代表的な組成のものを挙げれば次のよ
うなものがある。
(1)セリウムミツシユメタル
Ce： 45〜60、その他の希土類35〜50、残部は
Fe、Mg、Al、Si及び不純物（以上重量％）
(2)ランタンミツシユメタル
La： 60〜90、Ce：8.5、Nd：6.5、Pr：２、
Fe：0.2、Mg：0.03、Al：0.18、Si：0.43及び
残部は不純物（以上重量％）
点状不めつきの発生個数は希土類元素単体およ
びびミツシユメタルのいずれを用いるにせよ、そ
の添加量が増加する程減少する。添付図面は希土
類元素の添加量と点状不めつきの発生個数を調査
したものであるが、希土類元素が増加する程点状
不めつきは減少している。なおこの調査は前述の
アルミキルド鋼鋼板を露点−40℃、組成50％H2
−N2ガス（HNXガスとAXガスの混合ガス）中
で750℃、30秒還元焼鈍した後同一雰囲気下にあ
る680℃のAl−2.5％Si浴に３秒間浸漬してめつき
しためつき付着量片面80ｇ／m2の溶融Alめつき
鋼板より50mm×100mmのサンプルを採取して、そ
の両面に発生した点状不めつき個数を目視により
計数したものである。またセリウムミツシユメタ
ルとしては前述の組成のものを用いた。
しかしながら添付図面より明らかな如く、希土
類元素の添加量が0.01重量％より少くなると点状
不めつきの発生個数は急激に増加する。一方添加
量が1.0重量％を超えると工業的製造の場合製造
コストが著しく上昇するとともに、浴中で重量偏
析してしまい、多く添加した効果が発揮されな
い。このため希土類元素の添加は0.01〜1.0重量
％にするのが好ましい。なお希土類元素のアルミ
ニウム浴中への溶解度は浴温650〜700℃で10重量
％前後であり、10重量％を超えるとAlと希土類
元素の金属間化合物が浴中に浮遊し、その添加が
治金学的に無意味となり、粗雑な外観の製品しか
得られない。
また希土類元素の添加効果は前記希土類元素の
添加量と不めつき発生個数の調査より明らかな如
くめつき浴にSiが添加されていても得られる。一
般に溶融Alめつき鋼板製造の際めつき浴にSiを
添加してもめつき性には何ら影響を与えず、合金
層の成長を抑制するのみであるので、希土類元素
添加効果はSi添加の有無に関係なく得られる。し
かしSiの添加は従来11重量％を超えるとめつき層
中に板状Siが初晶として晶出し、めつき層自体の
延性が極端に低下し、加工上好ましくなくなるこ
とから11重量％以下に制限しているので、本発明
においてもSi添加は11重量％以下にする。
以上のように希土類元素を添加すると露点が高
くても点状不めつきが減少するのであるが、その
機構については現在のところ明らかになつていな
い。しかし、希土類元素は比較的酸化されやすい
ので浴表面のアルミの酸化速度を抑え、かつ粘度
の高いアルミの酸化皮膜を分断させる作用がある
ことから、鋼板がめつき浴へ侵入する時にアルミ
の酸化皮膜の巻込みを抑制するものと推定され
る。
次に実施例により本発明を説明する。
実施例 １
板厚0.6mmのアルミキルド鋼鋼板を露点−46℃、
組成50％H2−N2の雰囲気ガス中で750℃、30秒
還元焼鈍した後同雰囲気下にある浴温720℃の純
Al浴およびこれに希土類元素としてLa、Ｙおよ
びNdをそれぞれ添加した浴に浸漬してめつき付
着量片面60ｇ／m2の溶融Alめつき鋼板を製造し
た。
得られた鋼板より50mm×100mmのサンプルを採
取して、その両面に発生した点状不めつきの個数
を計数した。第２表にこの点状不めつきの発生個
数をLa、CeおよびNdの各添加量とともに示す。[Table] In addition, the survey on the occurrence of spot defects in Table 1 shows melting.
Al-plated steel sheet and hot-dip galvanized steel sheet are the same plated base plate [C0.04, Si0.01, Mn0.28, P0.013,
S0.011, solAl0.015, residual Fe (more than % by weight) aluminum-killed steel sheet] was heated at 750℃.
Al-6.5%Si bath with bath temperature of 680℃ and bath temperature in the same atmosphere after 30 seconds reduction annealing in HNX gas atmosphere
This test was carried out on a steel plate obtained by plating by immersing it in a Zn-0.18% Al bath at 460°C for 3 seconds. The plating amount is 60g/ m2 on both sides,
The number of dot-like defects is determined by visually counting the dot-like defects that occurred on both sides of samples with sizes of 50 mm and 100 mm. If spot defects occur on the appearance, the appearance is good if the number is 5 or less/ dm2 , but 5
When the number of particles/dm 2 is exceeded, the appearance gradually deteriorates. For this reason, in order to reduce the number of spot defects to below 5/ dm2 , the dew point of the atmospheric gas at the snout was set at -50°C.
It was managed as follows. However, in order to reduce the dew point of the snout to -50°C or lower, the dew point of the atmospheric gas supplied to the pretreatment reduction zone must be set to -60°C or lower. Management was extremely difficult as it had to be strictly enforced. In view of this situation, the present invention provides a method for producing a hot-dip aluminized steel sheet that does not cause spot defects even without extremely lowering the atmospheric gas dew point of the snout portion. As mentioned above, spot defects on hot-dip aluminized steel sheets can be prevented to some extent by lowering the atmospheric gas dew point of the pretreatment reduction zone to -50°C or less at the snout. It has been found that the reason why sticking does not occur is because the oxide film present on the surface of the plating bath on the snout portion is reduced. That is, since Al is more easily oxidized and has a higher melting point than Zn, an oxide film is likely to be formed on the surface of the plating bath if the dew point of the snout portion is the same. Therefore, the dew point of the snout is -30 to -
When the temperature is 40℃, an oxide film is not significantly formed on the surface in a zinc bath, but a significant amount is formed in an aluminum bath, and when the steel plate enters the plating bath through the snout, the oxide film is dragged in and spots are formed. occurs. Therefore, if the dew point of the snout portion is lowered, the amount of oxide film formed on the surface of the plating bath will be reduced, and spot defects will no longer occur. However, since there are problems as mentioned above in reducing the dew point of the snout part to below -50°C, the present inventors investigated a method that does not require the dew point of the snout part to be extremely low in terms of bath composition. They discovered that it is sufficient to add 0.01 to 1.0% by weight of rare earth elements to the plating bath. When we investigated the effects of various rare earth elements, we found that La, Ce, Nd,
Pr and Y are preferable, and it has been found that even if two or more of these rare earth elements are added, the same effect can be obtained as long as the total amount is the same as in the case of one type. Thus, in the present invention, a steel plate is reduced in a pretreatment reduction zone with an atmospheric gas having a hydrogen concentration of 11% or more, and then immersed in an aluminum bath whose bath surface is covered with the same atmospheric gas through a snout filled with the same atmospheric gas. When producing hot-dip aluminum-plated steel sheets using a Sendzimer-type hot-dip plating line, La, Ce, Nd,
0.01 to 1.0% by weight of one or more of Pr, Y and
The present invention provides a method for producing a hot-dip Al-plated steel sheet, which comprises adding 0 to 11% by weight of Si and hot-melting the steel sheet. In the present invention, the rare earth element added to the plating bath may be a single rare earth element, but since the rare earth element alone is expensive, Mitsushi Metal (a mixed rare earth element with its natural composition) is used, which is industrially inexpensive. Advantageously, metals are used. Typical compositions of lanthanum metal and cerium metal are as follows. (1) Cerium Mitsushi Metal Ce: 45-60, other rare earths 35-50, the balance
Fe, Mg, Al, Si and impurities (weight%) (2) Lanthanum Mitsushi Metal La: 60-90, Ce: 8.5, Nd: 6.5, Pr: 2,
Fe: 0.2, Mg: 0.03, Al: 0.18, Si: 0.43, and the rest are impurities (more than % by weight) The number of spot defects will increase as the amount of rare earth elements added increases, regardless of whether rare earth elements are used alone or rare earth metals are used. The more you do, the more it decreases. The attached drawing shows an investigation of the amount of rare earth elements added and the number of dotted defects, and it is found that the more rare earth elements are added, the more the dotted defects decrease. In this investigation, the above-mentioned aluminium-killed steel sheet was tested at a dew point of -40℃ and a composition of 50% H2.
- Reductive annealing at 750℃ for 30 seconds in N2 gas (mixed gas of HNX gas and AX gas), followed by immersion in an Al-2.5%Si bath at 680℃ in the same atmosphere for 3 seconds for plating. A 50 mm x 100 mm sample was taken from a hot-dip Al-plated steel plate with a coating weight of 80 g/m 2 on one side, and the number of dotted spots occurring on both sides was visually counted. Furthermore, the cerium metal having the above-mentioned composition was used. However, as is clear from the accompanying drawings, when the amount of rare earth element added is less than 0.01% by weight, the number of spot defects increases rapidly. On the other hand, if the amount added exceeds 1.0% by weight, the manufacturing cost will increase significantly in industrial production, and the weight will segregate in the bath, so that the effect of adding a large amount will not be exhibited. For this reason, it is preferable that the rare earth element be added in an amount of 0.01 to 1.0% by weight. The solubility of rare earth elements in an aluminum bath is around 10% by weight at a bath temperature of 650 to 700°C, and if the solubility exceeds 10% by weight, intermetallic compounds of Al and rare earth elements will float in the bath, and their addition will be difficult. It becomes meaningless metallurgically, and only a product with a rough appearance can be obtained. Furthermore, the effect of adding rare earth elements can be obtained even when Si is added to the plating bath, as is clear from the investigation of the amount of rare earth elements added and the number of defects. In general, adding Si to the plating bath during the production of hot-dip Al-plated steel sheets has no effect on plating properties and only suppresses the growth of the alloy layer. obtained regardless of. However, the addition of Si has traditionally been limited to 11% by weight or less because if it exceeds 11% by weight, plate-like Si will crystallize as primary crystals in the plated layer, resulting in an extreme decrease in the ductility of the plated layer itself, making it unfavorable for processing. Therefore, in the present invention as well, the amount of Si added is 11% by weight or less. As described above, addition of rare earth elements reduces spot stains even at high dew points, but the mechanism is not clear at present. However, since rare earth elements are relatively easily oxidized, they have the effect of suppressing the oxidation rate of aluminum on the bath surface and breaking up the highly viscous oxide film of aluminum, so when the steel plate enters the plating bath, the oxide film of aluminum It is estimated that this suppresses the entrainment of Next, the present invention will be explained with reference to Examples. Example 1 An aluminum killed steel plate with a thickness of 0.6 mm was heated to a dew point of -46°C.
After reduction annealing at 750℃ for 30 seconds in an atmosphere gas with a composition of 50% H 2 - N 2 , a pure product with a bath temperature of 720℃ under the same atmosphere.
A hot-dip Al-plated steel plate with a plating weight of 60 g/m 2 on one side was produced by immersing it in an Al bath and a bath to which La, Y, and Nd were added as rare earth elements. A 50 mm x 100 mm sample was taken from the obtained steel plate, and the number of dotted spots that occurred on both sides of the sample was counted. Table 2 shows the number of dotted spots along with the amounts of La, Ce, and Nd added.
【表】
第２表よりSiを添加しない浴においても希土類
元素の添加量が0.01重量％を越えると点状不めつ
きの発生個数の減少が顕著に認められる。また従
来の希土類元素を添加しない浴では浴表面近傍の
雰囲気露点が−52℃以下とならないと健全なめつ
き表面が得られないのに対して、希土類元素を
0.01重量％を越えて添加した場合には、雰囲気露
点が−46℃でもほぼ健全なめつき表面の得られる
ことがわかる。
しかし、添加量が10重量％を越えると、めつき
表面にドロス引きを生じ、著しく表面外観が損わ
れ、めつき製品として供し得なくなる。
実施例 ２
実施例１と同様の鋼板を組成50％H2−N2の雰
囲気ガス中で種々露点を変化させて750℃、30秒
還元焼鈍した後同雰囲気下にある670℃のAl−8.5
％Si浴およびこれにCeまたはランタンミツシユ
メタルを各0.1重量％添加した浴に浸漬してめつ
き付着量片面80ｇ／m2の溶融Alめつき鋼板を製
造した。その後実施例１と同要領で点状不めつき
の発生個数を計数し、第３表にまとめた。なおラ
ンタンミツシユメタルとしては前述の組成のもの
を使用した。[Table] From Table 2, even in baths to which Si is not added, when the amount of rare earth element added exceeds 0.01% by weight, a remarkable decrease in the number of spot defects is observed. In addition, with conventional baths that do not contain rare earth elements, a healthy plated surface cannot be obtained unless the atmospheric dew point near the bath surface falls below -52°C.
It can be seen that when added in an amount exceeding 0.01% by weight, a substantially sound plated surface can be obtained even at an atmospheric dew point of -46°C. However, if the amount added exceeds 10% by weight, dross will form on the plated surface and the surface appearance will be significantly impaired, making it impossible to use it as a plated product. Example 2 A steel plate similar to Example 1 was reduction annealed at 750°C for 30 seconds in an atmospheric gas with a composition of 50% H2 - N2 at various dew points, and then annealed at 670°C in the same atmosphere with Al-8.5.
%Si bath and a bath to which 0.1% by weight of Ce or lanthanum metal was added to produce hot-dip Al-plated steel sheets with a plating weight of 80 g/m 2 on one side. Thereafter, the number of spot defects was counted in the same manner as in Example 1 and summarized in Table 3. The lanthanum metal used had the composition described above.
【表】
１と同じである。
第３表よりCeまたはランタンミツシユメタル
を添加すると浴表面近傍の露点が同温度でも点状
不めつきの発生個数を少くすることができる。ま
た露点を無添加の場合に比べて約５℃高くしても
ほぼ同等の製品を得ることができる。
以上詳細に述べたようにめつき浴中に希土類元
素を0.01〜1.0重量％添加すれば前処理還元帯の
雰囲気ガス露点を従来より５℃以上高くでき、し
かも添加量を1.0重量％に近づければ溶融亜鉛め
つき鋼板製造の場合の露点に近傍させることがで
きるので、製造管理は容易になる。[Table] Same as 1.
Table 3 shows that when Ce or lanthanum metal is added, the number of spot defects can be reduced even if the dew point near the bath surface is the same temperature. Furthermore, even if the dew point is increased by about 5° C. compared to the case without additives, a substantially equivalent product can be obtained. As described in detail above, by adding 0.01 to 1.0% by weight of rare earth elements into the plating bath, the atmospheric gas dew point in the pretreatment reduction zone can be made higher by 5°C or more than before, and the amount of addition can approach 1.0% by weight. For example, since the dew point can be set close to the dew point in the production of hot-dip galvanized steel sheets, production control becomes easier.
添付図面は露点−40℃、組成50％H2−N2雰囲
気ガス中でアルミキルド鋼網板を750℃、30秒間
還元焼鈍した後同雰囲気下にあるAl−2.5％Si浴
（浴温680℃）に３秒間浸漬してめつきした溶融
Alめつき鋼板に発生した点状不めつきの個数と
浴中へ添加したLa、Ceおよびセリウムミツシユ
メタルの添加量との関係を示すものである。
The attached drawing shows an Al-2.5% Si bath in the same atmosphere (bath temperature 680°C) after reduction annealing an aluminum killed steel mesh plate at 750° C for 30 seconds in an atmosphere gas with a dew point of -40°C and a composition of 50% H2-N2. ) for 3 seconds.
This figure shows the relationship between the number of spot defects that occurred on an Al-plated steel sheet and the amounts of La, Ce, and cerium metal added to the bath.
Claims (1)
雰囲気ガスで還元した後、同雰囲気ガスの充たさ
れたスナウトより浴面が同雰囲気ガスに覆われた
アルミニウム浴に浸漬して溶融めつきするセンジ
マータイプの溶融めつきラインにより溶融アルミ
ニウムめつき鋼板を製造する際、アルミニウム浴
にLa、Ce、Nd、Pr、Ｙのうちの１種以上を0.01
〜1.0重量％およびSiを０〜11重量％添加して溶
融めつきすることを特徴とする溶融アルミニウム
めつき鋼板の製造方法。 ２ La、Ce、Nd、Pr、Ｙの添加をミツシユメタ
ルを用いて行うことを特徴とする特許請求の範囲
第１項に記載の溶融アルミニウムめつき鋼板の製
造方法。[Scope of Claims] 1. An aluminum bath in which the bath surface is covered with the atmospheric gas from a snout filled with the same atmospheric gas after a steel plate is reduced with an atmospheric gas having a hydrogen concentration of 11% or more in a pretreatment reduction zone. When producing hot-dip aluminum-plated steel sheets using a Sendzimer-type hot-dip plating line that immerses them in hot-dip plating lines, one or more of La, Ce, Nd, Pr, and Y is added to the aluminum bath at a concentration of 0.01.
1. A method for producing a hot-dip aluminum plated steel sheet, which comprises adding 0 to 11 wt% of Si and 0 to 11 wt% of hot-dip aluminum. 2. The method for producing a molten aluminum-plated steel sheet according to claim 1, wherein La, Ce, Nd, Pr, and Y are added using Mitsushi Metal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6163684A JPS60204875A (en) | 1984-03-29 | 1984-03-29 | Manufacture of alumin hot dip aluminum coated steel sheet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6163684A JPS60204875A (en) | 1984-03-29 | 1984-03-29 | Manufacture of alumin hot dip aluminum coated steel sheet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60204875A JPS60204875A (en) | 1985-10-16 |
| JPH0428781B2 true JPH0428781B2 (en) | 1992-05-15 |
Family
ID=13176880
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6163684A Granted JPS60204875A (en) | 1984-03-29 | 1984-03-29 | Manufacture of alumin hot dip aluminum coated steel sheet |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60204875A (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003293108A (en) * | 2002-04-04 | 2003-10-15 | Nippon Steel Corp | Hot dip plated steel having excellent surface smoothness |
| JP2004244655A (en) * | 2003-02-12 | 2004-09-02 | Nippon Steel Corp | HOT DIP Al BASED PLATED STEEL SHEET HAVING EXCELLENT CORROSION RESISTANCE, AND PRODUCTION METHOD THEREFOR |
| JP2009120942A (en) * | 2007-10-24 | 2009-06-04 | Nippon Steel Corp | Aluminum alloy plated steel sheet having excellent cut edge face corrosion resistance and worked part corrosion resistance |
| JP2009120943A (en) * | 2007-10-24 | 2009-06-04 | Nippon Steel Corp | Aluminum-based alloy plated steel sheet having excellent oxidation resistance and spot weldability |
| JP5532552B2 (en) * | 2008-06-09 | 2014-06-25 | 新日鐵住金株式会社 | Hot-dip Al alloy plated steel |
| CN103754968A (en) * | 2014-02-26 | 2014-04-30 | 辽宁中成永续水工科技有限公司 | Method for manufacturing hot method sea water desalination device from entire aluminum hot-dip coated steel prepared by using two-bath process |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58177450A (en) * | 1982-04-13 | 1983-10-18 | Nisshin Steel Co Ltd | Manufacture of composite hot dipped steel plate |
-
1984
- 1984-03-29 JP JP6163684A patent/JPS60204875A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58177450A (en) * | 1982-04-13 | 1983-10-18 | Nisshin Steel Co Ltd | Manufacture of composite hot dipped steel plate |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60204875A (en) | 1985-10-16 |
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