1341870 ⑴ 九、發明說明 【發明所屬之技術領域】 且特別 本發明係有關一種銘合金板及其製造方法 者’其係關於-種鋁合金板，其爲〜種適用於車體平板及 類似者之成形材料。 【先前技術】 例如’車輛之本體板至今主要係由冷軋鋼板製成。不 過’根據對減少車體重量之要求，已於最近硏究A丨_Mg 基底、Al-Mg-Sl基底、及類似者之鋁合金板的使用。 一般所知用於製造此等銘合金板之方法包括—方法， 其中係以D C鑄造法（半連續鑄造法）鑄造平板，係將該 扁胚剝蝕（scalping)且所得之扁胚插置於—批次型爐內 進行勻化處理（燜浸）數小時至約1 0小時，接著進行熱軋 步驟 '冷軋步驟、以及退火步驟，以製成有預定厚度之平 板（參考例如·ΙΡΡ3 ] 5567 8)。 再者，也已知有一種雙帶鑄造法（twin be丨t casting method )，其中係裝置一對平行對立旋轉循環皮帶，將鋁 合金熔融物導至循環帶之間的間隙，且在冷卻時連續地取 出，接著繞在一圈上（參考例如 PCT W0 2002/0 Π922 (JP2004-505774A) 〇 不過，關於上述之DC鑄造法，由於鑄造期間熔融物 之冷卻速率係相對低到1至約1 0 ° C /秒，因此在基體 (matrix)中結晶的金屬間化合物，例如，A 1 · (F e · Μ π)- -6- (2) (2)13418701341870 (1) IX. Description of the invention [Technical field to which the invention pertains] In particular, the present invention relates to a type of alloy plate and a method for manufacturing the same, which is a type of aluminum alloy plate, which is suitable for a vehicle body plate and the like. Forming material. [Prior Art] For example, the body plate of the vehicle has hitherto been mainly made of cold rolled steel sheets. However, the use of aluminum alloy sheets of A丨_Mg substrate, Al-Mg-Sl substrate, and the like has recently been studied in accordance with the requirements for reducing the weight of the vehicle body. It is generally known that a method for producing such an alloy plate includes a method in which a flat plate is cast by a DC casting method (semi-continuous casting method), and the flat embryo is scalped and the resulting flat embryo is inserted - The batch type furnace is subjected to homogenization treatment (dip immersion) for several hours to about 10 hours, followed by a hot rolling step 'cold rolling step, and an annealing step to prepare a flat plate having a predetermined thickness (refer to, for example, ΙΡΡ3) 5567 8). Furthermore, a twin betw casting method is also known in which a pair of parallel opposite rotating endless belts are used to guide the aluminum alloy melt to the gap between the endless belts, and when cooled It is taken out continuously and then wound on a turn (refer to, for example, PCT W0 2002/0 Π922 (JP2004-505774A). However, with respect to the above-described DC casting method, the cooling rate of the melt during casting is relatively low to 1 to about 1. 0 ° C / sec, therefore intermetallic compounds crystallized in the matrix, for example, A 1 · (F e · Μ π) - -6- (2) (2) 1341870
Si ’其尺寸可能成長到10至數十微米，特別是在扁胚之 中央部份內者。此一金屬間化合物可能對通過滾壓與退火 步驟製備之最終退火平板所具沖壓成形性（press formability )有不良效應》 亦即，當最終退火平板形變時，如果金屬間化合物之 尺寸相當大，則在金屬間化合物與基體之間易於發生剝離 (所謂孔隙）。結果，可能發生由此剝離部份開始的微裂 縫’以致劣化沖壓成形性。再者，於冷軋期間在金屬間化 合物附近會累積錯位（dislocation)，且在退火期間此等 錯位成爲再結晶之成核部位（nucleation site)。因此， 如果該金屬間化合物變大，則每單位體積之金屬間化合物 數目會減少，且從而再結晶顆粒之成核部位濃度會減少。 結果，該再結晶顆粒尺寸會增加數十微米，且劣化其沖壓 成形性。 在習知方法中，係採用高Mg合金以改善該沖壓成形 性。不過，如果增加M g含量，在實施沖壓成形之後，在 顆粒邊界會隨著時間沉澱出呈膜形狀的β相，且，從而， 劣化應力腐蝕破裂抗性。 在習知的方法中，諸步驟，例如，在DC鑄造之後的 扁胚表面之剝蝕，勻化處理，熱軋，冷軋，以及立即退 火，均爲複雜者，因此，成本爲之增加。 另一方面，在帶式鑄造方法中，對以連續鑄造熔融物 製造出之扁胚進行冷軋，且因此，相較於D C鑄造法內之 步驟，其優點爲步驟簡化且可降低製造成本。 (3) (3)1341870 不過，同樣地於此帶式鑄造法中，尙未曾進行有關改 善品質之硏究’例如最終退火平板之沖壓成形性與應力腐 蝕破裂抗性。 【發明內容】 本發明之目標是要用帶式鑄造法製造一種鋁合金板’ 其具有優越的沖壓成形性與應力腐蝕破裂抗性。 爲克服上述之問題，用於本發明之鋁合金板錠（slab ingot )係藉由用雙帶型鑄造機將含有3.3至3.6重量％的 Mg與0.1至0.2重量％的Μη，以及0.05至0.3重量％的 Fe與0.05至0.]5重量％的Si且其餘部份包括Α1與偶然 的雜質之熔融物鑄造成爲5至15毫米厚之扁胚，使得表 面下四分之一厚度的區域以20°C/秒至200°C/秒的冷卻速 率冷卻。 該所得鋁合金板錠係經直接捲繞在一筒上，將該板錠 用一表面粗糙度Ra 0.2至0.8微米之輥軋滾筒冷軋，且， 之後，進行退火使得該金屬間化合物之尺寸成爲5微米或 更小者，該最終退火平板之平板表面下1 〇至3 0微米區域 內之再結晶顆粒尺寸成爲1 5微米或更少，且該表面粗糙 度變成Ra 0.2至0.7微米。結果，可製成一種具有優越的 沖壓成形性與應力腐蝕破裂抗性之鋁合金板。 【實施方式】 下面要參照本發明具體實例進行說明。根據本具體實 -8- (4) (4)1341870 例’將熔融物導至雙帶型鑄造機內，連續鑄造一扁胚，且 將所得扁胚捲至滾筒上。對於該雙帶型鑄造機，係裝置， 例如’ 一對平行對立旋轉循環皮帶，將該熔融物導到皮帶 間夾住的平坦部份內’且順著皮帶之轉動傳輸，使得該熔 融物冷卻’從而’連續鑄造一具有預定板厚之扁胚。 用該雙帶型鑄造機鑄造之扁胚所具總厚度爲例如5至 15毫米’且相對於總板厚，在該表面下四分之一厚度的 區域’在鑄造期間係以20。C/秒至200°C/秒之冷卻速率冷 卻。結果’在該最終退火平板之平板表面下10至30微米 深的區域內之Al-(Fe*Mn)-Si基底及類似者之金屬間化合 物所具尺寸變成很細的5微米或更小。因此，即使當該最 終退火平板形變時，在該金屬間化合物與基體之間的剝離 也難以發生’且相較於其中會發生由剝離部份開始的微破 裂之D C鑄造軋成平板，具有優越的沖壓成形性。 再者，在冷軋期間錯位會累積於該金屬間化合物附 近，且此等錯位會成爲再結晶之成核部位。就扁胚之冷軋 平板的情形而言，其中該金屬間化合物之尺寸相當小，每 單位體積之金屬間化合物之數目會增加，且從而，增加再 結晶所用成核部位之濃度。結果，再結晶顆粒尺寸變成相 對較小的15微米或更小，且可製成一具有優越沖壓成形 性之最終退火平板》 除了上述之相對簡化的製造步驟之外，當對扁胚之冷 軋中所用的冷軋輥使用硏磨機及類似者予以拋光時，在本 具體實例中，輥的表面粗糙度係經控制於Ra 0.2至0.8微 (5) (5)U41870 米之圍內。在冷軋步驟期間，該軋輥表面之形狀會轉移 到^滾板表面’且從而使該最終退火平板之表面粗糙度 變成Ra 0.2微米至〇 7微米。當該最終退火平板之表面粗 縫度是在R a 0,2至〇 . 7微米範圍內時，該最終退火平板之 表面形狀具有微池（micr〇p〇d )之功用而在成形期間可 均勾保持住低黏度潤滑劑，且從而確保預定的沖壓成形 性。 下@要說明在本具體實例中對合金成分的限制之意義 # ί里由’以及限定於該最終退火平板中產生的該金屬間化 €物所具尺寸與再結晶顆粒所具尺寸、該最終退火平板之 表面粗糙度、鑄造扁胚期間之冷卻速率、冷軋輥之表面粗 糙度、及類似者之理由。 當鎂在基體中以固體溶液形式存在之時，該最終退火 平板之強度會增加，且此外，加工硬化性（work h a r d e n a b i 1 i t y )會增強而增加延展性，使沖壓成形性之改 善得以加速。添加量特定爲3.3至3 · 6重量％，因爲如果 小於3 .3重量％，則強度低且成形性不良，而如果大於 3.6重量％，則應力腐蝕破裂抗性（SCC抗性）劣化且增 加製造成本。 關於Μη，可使再結晶顆粒變細，此外，強度增加’ 且改善該沖壓成形性。添加量指定爲0.丨至〇.2重量％ ’ 因爲如果小於〇 · 1重量％，則效果無法適當顯現’而如果 大於0.2重量％，會增加 Α丨-(F e · Μ η ) - S i基底之金屬間化 合物，從而，減低材料之延展性，以致劣化車輛用之鋁板 -10- (6) (6)1341870 的成形性。 當使F e與Μ η和S i共存時，在鑄造期間會結晶成以 微細 A 1 - ( F e · Μ η) - S i爲基底之化合物，使再結晶顆粒變 細，且此外，強度也增加，使得沖壓成形性得以改善。如 果添加量小於〇 . 〇 5重量％，則其效果無法適當顯現，而如 果大於0.3重量％，在鑄造期間會增加相對較粗的以Α Ι-θ e · Μ η ) - S i 爲基 底的金 屬間化 合物之 數目， 以致減 少沖壓 成形性，且此外，扁胚內之Μ η固體溶液的量會減低，且 降低最終退火平板之強度。因此，F e含量較佳者係在 0.05至0.3重量％的範圍內，且更佳者爲0.05至0.2重量 %。 當使Si與Fe和Μη共存時，在鑄造期間會結晶成以 微細 Al-(Fe*Mn)-Si爲基底之化合物，使再結晶顆粒變 細，且此外，強度會增加。如果添加量小於0.0 5重量％ , 則效果無法適當顯現，如果大於〇 · 1 5重量。/。，則以 a 1 · (Fe*Mn)-Si爲基底的金屬間化合物之數目在鑄造期間會增 加，以致降低沖壓成形性，且此外，扁胚內Μ η固體溶 '液 之量會減低，且會降低最終退火平板之強度。因此，S i 含量較佳者係在〇 · 〇 5至〇 . 1 5重量％的範圍內，更佳者爲 0.0 5 至 0.1 0 重量 ％。 較佳者，最終退火平板之板面下1 〇至3 0微米深的區 域內之該金屬間化合物所具尺寸爲5微米或更小。於將該 最終退火平板形變的情形中，當該金屬間化合物之尺寸爲 5微米或更小時，在該金屬間化合物與基體之間難以發生 -11 - (7) (7)1341870 剝離，且會抑制由剝離部份開始的微裂縫之發生，並改善 其沖壓成形性。當該金屬間化合物之尺寸爲5微米或更小 時，每單位體積之金屬間化合物數目會增加，從而，增加 再退火時結晶之成核部位濃度。結果*該再結晶顆粒之尺 寸變成相對較小的】5微米或更小，且展現改善該沖壓成 形性的效果。 較佳者，該最終退火平板之板面層內之再結晶顆粒之 尺寸爲15微米或更小。如果該尺寸超過15微米，不僅劣 化成形性，而且材料形變中在顆粒周邊產生的高度差異變 成太大，形變後之橘皮面現象（orange peel)變爲顯著， 且從而劣化沖壓成形後之表面品質。 較佳者，該最終退火平板之表面粗糙度爲Ra 0.2至 〇 . 7微米。如果該表面粗糙度小於R a 0 · 2微米，留住形成 該最終退火平板中使用的低黏性潤滑劑之微池的形成會不 足，且從而，變成難以使潤滑劑均勻地滲透至板面與壓模 之間的介面內，以致無法改善沖壓成形性。另一方面，如 果該表面粗糙度超過Ra 0·7微米，則微池會稀疏且不均 勻地分布在該最終退火平板上，且從而，變成難以將潤滑 劑均勻地保留於板面上，以致無法改善沖壓成形性。最終 退火平板之表面粗糙度更佳者係在Ra0.3至0.6微米。 該合金成分可包含0 .] 0重量％或更小之鑄造扁胚所用 顆粒精練劑（例如，Ti )。此外，該合金成分可包含呈雜 質形式的C υ、V、Z r、和類似者，各別含量爲〇 . 〇 5重量％ 或更低。 -12- (8) 1341870 下面將說明對鑄造扁胚所用條件之限制所具意 由。用雙帶型鑄造機製造之扁胚厚度係定在5至1 的範圍內，因爲如果該厚度小於5毫米，則單位時 過鑄造機的熔融物量之會太小，因此，變成難以 造’而如果該厚度超過1 5毫米，則用輥無法捲繞。 關於以DC鑄造法製成的扁胚，扁胚具有大厚 在金屬結構中，結晶於扁胚中央部份內之金屬間 (例如 Al-(Fe*Mn)-Si )可能具有達到十至數十微 寸’因爲冷卻速率相對低到]度至十幾度/秒之故 情形而言，在塑造形變期間可能在金屬間化合物與 間發生剝離現象以致對沖壓成形性有不良影響。 面’關於本具體實例之雙帶型鑄造機，可捽制扁胚 減低的厚度，表面下四分之一板厚之區域的冷卻速 加爲20°C/秒至200°C/秒之間，且從而，最終退火 板面下1 0至3 0微米深之區域內的金屬間化合物之 變成5微米或更小。 關於冷軋輥，該輥表面之表面粗糙度係定爲 至〇. 8微米以控制最終退火平板之表面粗糙度。由 面之形狀在冷軋步驟期間被轉移到輥軋平板的表面 終退火平板之表面粗糙度即變成Ra 0.2至0.7微米 終退火平板之表面粗糙度是在Ra 0.2至0.7微米的 時，該最終退火平板之表面形狀有微池的作用以均 住成形期間所用之低黏度潤滑劑，從而，得以提供 沖壓成形性之平板。由於最終退火平板之表面粗糙 義與理 5毫米 間內通 實施鑄 度，且 化合物 米之尺 。就此 基體之 另一方 以具有 率可增 平板之 尺寸可 Ra 0.2 於輥表 上，最 。當最 範圍內 勻地留 有優越 度更佳 -13- (9) 1341870 者係Ra 0.3至0 · 6微米，因此該冷軋輥之表面粗糙度更佳 地係定爲R a 0.3至0.7微米。 如上述，根據本具體實例，可提供一種具有優越的沖 壓成形性與應力腐蝕破裂抗性之鋁合金板，特別是，一種 適用於車輛之鋁合金板。 實施例 下面要說明本發明之實施例，且與比較性實施例作比 較。將具有表1 (實施例）所示的組成A之熔融物除氣與 沈降’且隨後’用一雙皮帶鑄造機鑄造一扁胚。將所得扁 胚用一冷軋輥冷軋爲1毫米厚之平板。將所得平板在 420°C連續退火（CAL)，且從而，製成一最終退火平板 之測試板。表2 (實施例]至3 )示出測試板在每一製程 中之製造條件之實施例。Si' may grow in size from 10 to tens of microns, especially in the central portion of the flat embryo. This intermetallic compound may have an adverse effect on the press formability of the final annealed sheet prepared by the rolling and annealing steps, that is, when the final annealed sheet is deformed, if the size of the intermetallic compound is relatively large, Then, peeling (so-called void) is liable to occur between the intermetallic compound and the matrix. As a result, microcracks starting from the peeling portion may occur so as to deteriorate the press formability. Further, dislocation is accumulated in the vicinity of the intermetallic compound during cold rolling, and these misalignments become nucleation sites for recrystallization during annealing. Therefore, if the intermetallic compound becomes large, the number of intermetallic compounds per unit volume is decreased, and thus the concentration of the nucleation sites of the recrystallized particles is reduced. As a result, the size of the recrystallized particles is increased by several tens of micrometers, and the stamp formability thereof is deteriorated. In the conventional method, a high Mg alloy is used to improve the press formability. However, if the Mg content is increased, after the press forming is performed, the β phase in the shape of a film precipitates at the grain boundary with time, and, thus, deteriorates the stress corrosion crack resistance. In the conventional method, steps such as ablation of the surface of the flat embryo after DC casting, homogenization treatment, hot rolling, cold rolling, and immediate annealing are complicated, and therefore, the cost is increased. On the other hand, in the belt casting method, the flat bristles produced by continuously casting the melt are cold-rolled, and therefore, compared with the steps in the D C casting method, the advantage is that the steps are simplified and the manufacturing cost can be reduced. (3) (3) 1341870 However, similarly in this belt casting method, there has been no research on the improvement of quality, such as press formability and stress corrosion cracking resistance of the final annealed sheet. SUMMARY OF THE INVENTION An object of the present invention is to produce an aluminum alloy sheet by a belt casting method which has superior press formability and stress corrosion crack resistance. In order to overcome the above problems, the aluminum alloy ingot (slab ingot) used in the present invention contains 3.3 to 3.6% by weight of Mg and 0.1 to 0.2% by weight of Μ, and 0.05 to 0.3 by using a double belt type casting machine. The weight % of Fe and 0.05 to 0.5% by weight of Si and the remainder including the melt of Α1 and incidental impurities are cast into 5 to 15 mm thick slabs, so that the area under the surface of a quarter thickness is Cooling at a cooling rate of 20 ° C / sec to 200 ° C / sec. The obtained aluminum alloy ingot is directly wound on a cylinder, and the ingot is cold rolled by a rolling mill having a surface roughness Ra of 0.2 to 0.8 μm, and then, annealed to make the size of the intermetallic compound. When it is 5 μm or less, the recrystallized grain size in the region of 1 〇 to 30 μm under the surface of the plate of the final annealed plate becomes 15 μm or less, and the surface roughness becomes Ra 0.2 to 0.7 μm. As a result, an aluminum alloy sheet having excellent press formability and stress corrosion crack resistance can be produced. [Embodiment] Hereinafter, a specific example of the present invention will be described. According to the present embodiment -8-(4) (4) 1341870, the molten material is guided into a double-belt type casting machine, a flat embryo is continuously cast, and the obtained flat embryo is wound onto a drum. For the two-belt type casting machine, a device such as a pair of parallel counter-rotating circulating belts guides the melt into a flat portion sandwiched between the belts and transmits along the rotation of the belt to cool the melt 'Thus' continuously casts a flat embryo having a predetermined plate thickness. The flat embryo cast by the double belt type casting machine has a total thickness of, for example, 5 to 15 mm' and a region of a quarter thickness below the surface with respect to the total sheet thickness is 20 during casting. The cooling rate from C/sec to 200 °C/sec is cooled. As a result, the Al-(Fe*Mn)-Si substrate and the like intermetallic compound in the region of 10 to 30 μm deep under the surface of the flat plate of the final annealed plate were made to have a fineness of 5 μm or less. Therefore, even when the final annealed flat plate is deformed, the peeling between the intermetallic compound and the matrix is hard to occur 'and is superior to the DC casting in which the micro-cracking from the peeling portion occurs, and the sheet is superior. Stamping formability. Further, misalignment may accumulate near the intermetallic compound during cold rolling, and such misalignment may become a nucleation site for recrystallization. In the case of a cold-rolled flat sheet of flat embryos, in which the size of the intermetallic compound is relatively small, the number of intermetallic compounds per unit volume increases, and thus, the concentration of the nucleation sites used for recrystallization is increased. As a result, the size of the recrystallized particles becomes a relatively small 15 micrometers or less, and a final annealed flat sheet having superior press formability can be produced. In addition to the relatively simplified manufacturing steps described above, cold rolling of flat embryos is performed. When the cold roll used in the polishing is polished using a honing machine and the like, in this embodiment, the surface roughness of the roll is controlled within a range of Ra 0.2 to 0.8 micro (5) (5) U41870 m. During the cold rolling step, the shape of the roll surface is transferred to the surface of the roll plate and the surface roughness of the final annealed plate is changed to Ra 0.2 μm to 7 μm. When the surface roughness of the final annealed plate is in the range of R a 0,2 to 7. 7 μm, the surface shape of the final annealed plate has the function of a micro-cell (micr〇p〇d) and can be used during forming. Both hooks hold the low-viscosity lubricant and thereby ensure a predetermined press formability. Next, it is necessary to explain the meaning of the limitation of the alloy composition in this specific example. The size and the size of the recrystallized particles produced by the 'intercalation of the final annealed plate are the same as the size of the recrystallized particles. The surface roughness of the annealed plate, the cooling rate during casting of the flat blank, the surface roughness of the cold roll, and the like. When magnesium is present as a solid solution in the matrix, the strength of the final annealed sheet is increased, and further, work hardening (work h a r d e n a b i 1 i t y ) is enhanced to increase ductility, and the improvement of press formability is accelerated. The amount of addition is specifically 3.3 to 3.6 wt%, because if it is less than 3.3 wt%, the strength is low and the formability is poor, and if it is more than 3.6% by weight, the stress corrosion crack resistance (SCC resistance) is deteriorated and increased. manufacturing cost. With respect to Μη, the recrystallized particles can be made fine, and the strength is increased, and the press formability is improved. The amount of addition is specified to be 0. 丨 to 〇. 2% by weight ' because if it is less than 〇·1% by weight, the effect cannot be properly exhibited' and if it is more than 0.2% by weight, Α丨-(F e · Μ η ) - S is increased The intermetallic compound of the i-base, thereby reducing the ductility of the material, thereby deteriorating the formability of the aluminum plate-10-(6)(6)1341870 for the vehicle. When F e is made to coexist with Μ η and S i , it crystallizes into a compound based on fine A 1 - ( F e · Μ η) - S i during casting to make the recrystallized particles fine, and further, strength It is also increased to improve the press formability. If the amount added is less than 〇. 〇 5% by weight, the effect cannot be properly exhibited, and if it is more than 0.3% by weight, a relatively thick Α Ι - θ e · Μ η ) - S i is added during casting. The number of intermetallic compounds is such that the press formability is reduced, and further, the amount of the ηsolid solution in the slab is reduced, and the strength of the final annealed plate is lowered. Therefore, the Fe content is preferably in the range of 0.05 to 0.3% by weight, and more preferably 0.05 to 0.2% by weight. When Si is allowed to coexist with Fe and Μη, a compound based on fine Al-(Fe*Mn)-Si is crystallized during casting to make the recrystallized particles finer, and further, the strength is increased. If the amount added is less than 0.05% by weight, the effect cannot be properly exhibited, if it is greater than 〇 · 15 weight. /. The number of intermetallic compounds based on a 1 · (Fe*Mn)-Si may increase during casting, so that the press formability is lowered, and in addition, the amount of solid solution in the flat embryo is reduced. And will reduce the strength of the final annealed plate. Therefore, the content of S i is preferably in the range of 〇 · 〇 5 to 〇 15 % by weight, more preferably 0.0 5 to 0.1 0 % by weight. Preferably, the intermetallic compound in the region from 1 Å to 30 microns deep below the surface of the final annealed plate has a size of 5 microns or less. In the case of deforming the final annealed plate, when the size of the intermetallic compound is 5 μm or less, -11 - (7) (7) 1341870 peeling hardly occurs between the intermetallic compound and the matrix, and The occurrence of microcracks starting from the peeling portion is suppressed, and the press formability is improved. When the size of the intermetallic compound is 5 μm or less, the number of intermetallic compounds per unit volume increases, thereby increasing the concentration of nucleation sites of crystals during reannealing. As a result * the size of the recrystallized particles became relatively small] 5 μm or less, and exhibited an effect of improving the formability of the press. Preferably, the size of the recrystallized particles in the surface layer of the final annealed sheet is 15 microns or less. If the size exceeds 15 μm, not only the formability is deteriorated, but also the difference in height generated in the periphery of the particles in the material deformation becomes too large, and the orange peel after the deformation becomes remarkable, and thus the surface after the press forming is deteriorated. quality. Preferably, the surface of the final annealed sheet has a surface roughness of Ra 0.2 to 〇. 7 μm. If the surface roughness is less than R a 0 · 2 μm, the formation of the microcell which retains the low-viscosity lubricant used in the final annealing plate may be insufficient, and thus, it becomes difficult to uniformly permeate the lubricant to the surface of the plate. The interface between the mold and the stamper is such that the press formability cannot be improved. On the other hand, if the surface roughness exceeds Ra 0·7 μm, the microcells are sparsely and unevenly distributed on the final annealed flat plate, and thus, it becomes difficult to uniformly retain the lubricant on the plate surface, so that It is not possible to improve press formability. The surface roughness of the final annealed sheet is preferably from 0.3 to 0.6 μm. The alloy composition may comprise a particle scouring agent (e.g., Ti) for casting flat embryos of 0% by weight or less. Further, the alloy component may contain C υ, V, Z r , and the like in a heterogeneous form, each content being 〇 重量 5% by weight or less. -12- (8) 1341870 The meaning of the restrictions on the conditions used for casting flat embryos will be explained below. The thickness of the flat embryo made by the double-belt type casting machine is set in the range of 5 to 1, because if the thickness is less than 5 mm, the amount of melt per unit time of the casting machine will be too small, and thus it becomes difficult to manufacture. If the thickness exceeds 15 mm, the roller cannot be wound. Regarding the flat embryo made by the DC casting method, the flat embryo has a large thickness in the metal structure, and the metal (for example, Al-(Fe*Mn)-Si) crystallized in the central portion of the flat embryo may have a ten to several number. Ten micro inches 'Because the cooling rate is relatively low to -10 degrees/second, peeling may occur between the intermetallic compounds during molding deformation so as to have an adverse effect on press formability. For the double-belt type casting machine of this specific example, the thickness of the flat embryo can be reduced, and the cooling speed of the area under the surface of the quarter-thickness is increased from 20 ° C / sec to 200 ° C / sec. And, thereby, the intermetallic compound in the region of 10 to 30 μm deep under the surface of the final annealed sheet becomes 5 μm or less. Regarding the cold roll, the surface roughness of the roll surface is set to 8.0 microns to control the surface roughness of the final annealed plate. The surface roughness of the surface-annealed flat sheet which is transferred to the surface of the rolled flat sheet during the cold rolling step becomes Ra 0.2 to 0.7 μm. The surface roughness of the final annealed flat sheet is when Ra is 0.2 to 0.7 μm, which is the final The surface shape of the annealed flat plate has a function of a microcell to balance the low-viscosity lubricant used during the forming, thereby providing a flat sheet having press formability. Since the surface of the final annealed plate is rough and the inner diameter is 5 mm, the casting is carried out, and the compound is made of rice. On the other hand, the other side of the substrate can be increased in size by Ra 0.2 on the roll table, the most. When the optimum range is better, the superiority is better -13-(9) 1341870 is Ra 0.3 to 0 · 6 μm, so the surface roughness of the cold roll is more preferably set to R a 0.3 to 0.7 μm. As described above, according to the present specific example, an aluminum alloy sheet having superior press formability and stress corrosion crack resistance can be provided, and in particular, an aluminum alloy sheet suitable for a vehicle. EXAMPLES Examples of the invention are described below and compared with comparative examples. The melt having the composition A shown in Table 1 (Example) was degassed and settled 'and then' a single embryo was cast by a double belt casting machine. The resulting slab was cold rolled into a 1 mm thick plate by a cold roll. The resulting plate was continuously annealed (CAL) at 420 ° C, and thereby, a test plate of a final annealed plate was fabricated. Table 2 (Examples to 3) shows an example of the manufacturing conditions of the test board in each process.
[表】] -表1_合金組成(重量％ ) 合金 Mg Μη Fe Si ，施例 A 3.4 0.15 0.20 0.08 比較例 B 3.0 0.1 5 0.20 0.08 比較例 C 4.5 0.1 5 0.20 0.08 其餘係由鋁與偶然的雜質組成。 -14 - (10)1341870 [表2] 表2製程 合金 鑄造法/ 厚度(毫米） 冷卻速率 rc/秒） 熱軋 冷軋輥表 面粗糙度 Ra(微米) 板厚 (毫米） 退火 溫度 (°C) 實施例1 A 雙帶式/7 75 4fff / » \N 0.6 ] 420 實施例2 A 雙帶式/9 45 / 1、N 0.6 1 420 實施例3 A 雙帶式/5 100 並 / » \N 0.6 1 420 比較例1 B 雙帶式/7 75 / 1 0.6 1 420 比較例2 C 雙帶式/7 75 & 0.6 1 420 比較例3 A 雙帶式/7 75 姐 yi w 0.2 1 420 比較例4 A 雙帶式/7 75 M 1.0 1 420 比較例5 A DC/500 5 7毫米 0.6 1 420 比較例6 A 雙輕/7 250 無 0.6 1 420 隨後，測量所得測試板之再結晶顆粒尺寸、金屬間化 合物之最大尺寸、表面粗糙度、2 %屈服強度（0.2 % YS )、極限抗拉強度（UTS ) '伸長率（EL)、深沖壓高 度、及應力腐蝕破裂抗性（S C C抗性）使用壽命。 用截距法（intercept method )測量測試板之再結晶 顆粒尺寸。用偏光顯微鏡作出測試板中顆粒之相片（200 倍），於垂直與水平方向各劃3條直線，計數線上顆粒之 數目，並且以線長除該數目而測得之顆粒尺寸平均値作爲 測試板之再結晶顆粒尺寸。用一圖像分析儀（LUZEX )測 -15- (11) (11)1341870 量該金屬間化合物之尺寸。 測試板之表面粗糙度係一平均粗糙度r a，其中係根 據J I S B 0 6 0 1用表面粗糙度測試儀測量，測量方向爲與輥 軋方向垂直之方向’測量區間爲4毫米’且截止長度爲 0.8毫米。輥之表面粗糙度係一平均粗糙度，其中係以 表面粗糙度測試儀根據j I s B 0 6 0 1進行測量，測量方向爲 輥軋橫向’測量區域爲4毫米，且截止長度爲〇 · 8毫米， 如在測試板之表面粗糙度中者。 該深沖壓高度係表在隨後使用衝模斷裂時形成之臨界 高度。衝壓：4〇毫米直徑，肩部R: 8毫米，衝模：42.5 毫米直徑，肩部R: 8毫米。 關於S C C抗性之評估，係將最終退火平板以3 0 %之 冷軋縮減率冷軋’且在120。C中敏化處理（sensitiZation t r e a t m e n t ) 1星期。之後’施加對應至8 5 %屈服強度之應 力，連續實施浸泡在3 · 5 %鹽水中，且測量到裂縫出現所 經過的時間而疋爲s C C抗性壽命。 上述測量之結果列示於表3 (實施例1至3 )之中。 (12) (12)1341870 [表3 ] 測試板（最終退火平板）之微結構與性質 合金 再結晶顆 粒尺寸 (微米） 金屬間化 合物之最 大尺寸 (微米） 表面粗糙 度Ra (微米） 2%降伏 強度 (MPa) UTS (MPa ) EL (%) 深沖 壓高 度 (毫米) SCC 抗性使 用壽命 (天） 實施例 A 8 4 0.45 118 240 28 13.2 >30天 實施例 2 A 10 5 0.44 116 238 27 13.0 >30天 實施例 3 A 7 3 0.42 121 243 30 13.4 >30天 比較例 B 9 5 0.43 107 220 25 12.4 >30天 比較例 2 C 7 4 0.44 130 280 30 13.6 I天 比較例 3 A 8 4 0.1 119 242 28 12.1 >30天 比較例 4 A 8 4 0.8 120 243 29 12.5 >30天 比較例 5 A 22 15 0.45 105 235 28 12.4 >30天 比較例 6 A 54 2 0.35 100 223 27 12.3 >30天 (13) (13)1341870 以具有表]所示組成之熔融物在表2 (比較例]至 6 )所示製造條件下製造測試板。經由實施與實施例1至 3中相同項目的測量評定該等製成之測試板，且將測量結 果列示於表3 (比較例]至6 )之中。 關於實施例]至3 ’ M g含量爲適當的3 · 4 %，測試板 包括微細的再結晶顆粒與金屬間化合物，其表面有適當的 表面粗糙度Ra 0.42至0.45微米’因此，展現出優越的深 沖壓性及優越的SCC抗性。 亦即，關於實施例1至3 ’係將一熔融物引進至雙帶 型鑄造機內，連續鑄造一平板，且將所得平板捲繞在一輥 上。於鑄造期間進行冷卻，以使相對於板厚在表面下至少 四分之一厚度的區域以20°C/秒至200°C/秒之冷卻速率冷 卻。以此方式，關於最終退火平板之板面下深1 0至3 0微 米的區域內之微結構，可使以 Al-(Fe*Mn)-Si爲底之金屬 間化合物及類似物變成很細的5微米或更小。結果，在金 屬間化合物與基體之間的剝離難以發生，即使該最終退火 平板形變之時亦然，且可製成具有優越沖壓成形性的平 板。 由於金屬間化合物之尺寸相對較小，且此外，每單位 積體之數目增加’因此再結顆粒晶之成核部位濃度也增 加。結果，該再結晶顆粒尺寸變成相對較小的1 5微米或 更小’且從而，提供具有優越沖壓成形性的平板。 再者’於將在冷軋中要用到的輥用硏磨機拋光時，藉 由控制軋輥之表面粗糙度在R a 0.2王0.8微米的範圍內， -18- (14) 1341870 可使最終退火平板之表面粗糙度變成在R a 0 · 2至0 · 7 的限定範圍內，且從而，最終退火平板之表面形狀有 的作用而可均勻地留住成形時使用的低黏度潤滑劑， 以進一步改善沖壓成形性。 另一方面，在比較例1中，由於Mg含量爲 3.0 %，所有的極限抗拉強度與伸長度均不足，且呈現 的可深沖壓性。在比較例2中，由於M g含量高至4 · 所有的極限抗拉強度與伸長度都很好，但是呈現不 SCC抗性。 在比較例 3中，表面粗糙度 R a低至 0.]微米 此’表面較實施例]至3之表面更平滑，但是呈現不 可深沖壓性。在比較例4中，該表面粗糙度R a高3 微米，且因此’其表面較實施例1至3之表面更粗縫 也呈現不良的可深沖壓性。 在比較例5中’係使用—種d C鑄造材料。由於 造期間之冷卻速率相對較低，內含的再結晶顆粒與金 化合物均比實施例1至3中者稍微較粗，且展現不良 深沖壓性。在比較例6中，係使用一種雙輥鑄造材料 於在鑄造期間之冷卻速率太高，金屬間化合物比實施 至3中者較爲細’再結晶顆粒較粗，且展現不良的可 壓性。 如上述’以雙帶式鑄造機鑄造所得之鋁合金扁胚 接捲繞在一輥上，該扁胚係經用表面粗糙度爲Ra 〇 〇 · 8微米的乳I冷軋’且之後，進行退火，使得金磨 微米 微池 而得 低的 ，不良 5% . 良的 ，因 良的 I 0.8 ，且 在鑄 屬間 的可 。由 ，例1 深沖 係直 .2至 間化 -19- (15) (15)1341870 合物之尺寸變成5微米或更小，該最終退火平板之板面下 深]〇至3 0微米的區域內的再結晶顆粒尺寸變成]5微米 或更小，且表面粗糙度變成R a 0.2至0.7微米。結果，可 製成一具有優越的沖壓成形性與應力腐蝕破裂抗性之鋁合 金板。[Table]] - Table 1_Alloy composition (% by weight) Alloy Mg Μη Fe Si, Example A 3.4 0.15 0.20 0.08 Comparative Example B 3.0 0.1 5 0.20 0.08 Comparative Example C 4.5 0.1 5 0.20 0.08 The rest is made of aluminum with accidental Impurity composition. -14 - (10)1341870 [Table 2] Table 2 Process Alloy Casting Method / Thickness (mm) Cooling Rate rc / sec) Hot Rolling Cold Roller Surface Roughness Ra (Micron) Plate Thickness (mm) Annealing Temperature (°C) Example 1 A double belt type / 7 75 4fff / » \N 0.6 ] 420 Example 2 A double belt type / 9 45 / 1, N 0.6 1 420 Example 3 A double belt type/5 100 and / » \N 0.6 1 420 Comparative Example 1 B Double belt type / 7 75 / 1 0.6 1 420 Comparative example 2 C Double belt type / 7 75 & 0.6 1 420 Comparative example 3 A Double belt type / 7 75 Sister yi w 0.2 1 420 Comparison Example 4 A Double belt type / 7 75 M 1.0 1 420 Comparative Example 5 A DC/500 5 7 mm 0.6 1 420 Comparative Example 6 A Double light / 7 250 No 0.6 1 420 Subsequently, the recrystallized grain size of the obtained test plate was measured. Maximum size, surface roughness, 2% yield strength (0.2 % YS ), ultimate tensile strength (UTS) 'elongation (EL), deep drawing height, and stress corrosion cracking resistance (SCC resistance) ) Service life. The recrystallized particle size of the test plate was measured by an intercept method. A photo of the particles in the test plate (200 times) was made with a polarizing microscope, and three straight lines were drawn in the vertical and horizontal directions, the number of particles on the line was counted, and the average particle size measured by dividing the number by the line length was used as a test plate. Recrystallized particle size. The size of the intermetallic compound was measured by an image analyzer (LUZEX) -15-(11) (11) 1341870. The surface roughness of the test board is an average roughness ra, which is measured by a surface roughness tester according to JIS B 0 0 0 1 and the measurement direction is perpendicular to the rolling direction, the measurement interval is 4 mm and the cut-off length is 0.8 mm. The surface roughness of the roller is an average roughness, which is measured by a surface roughness tester according to j I s B 0 6 0 1 , and the measurement direction is the lateral direction of the roll. The measurement area is 4 mm, and the cut-off length is 〇· 8 mm, as in the surface roughness of the test board. This deep drawing height is the critical height that is subsequently formed when the die is broken. Stamping: 4 mm diameter, shoulder R: 8 mm, die: 42.5 mm diameter, shoulder R: 8 mm. Regarding the evaluation of S C C resistance, the final annealed sheet was cold rolled at a cold reduction rate of 30% and was at 120. Sensitization in C (sensitiZation t r e a t m e n t ) for 1 week. Thereafter, a stress corresponding to 85% yield strength was applied, and immersion in 3.5 % saline was continuously performed, and the time elapsed from the occurrence of the crack was measured and the s C C resistance life was measured. The results of the above measurements are shown in Table 3 (Examples 1 to 3). (12) (12) 1341870 [Table 3] Microstructure and properties of test plates (final annealed plates) Recrystallized grain size (micron) Maximum size of intermetallic compound (micron) Surface roughness Ra (micron) 2% fluctuating Strength (MPa) UTS (MPa) EL (%) Deep drawing height (mm) SCC Resistance service life (days) Example A 8 4 0.45 118 240 28 13.2 > 30 days Example 2 A 10 5 0.44 116 238 27 13.0 > 30 days Example 3 A 7 3 0.42 121 243 30 13.4 > 30 days Comparative Example B 9 5 0.43 107 220 25 12.4 > 30 days Comparative Example 2 C 7 4 0.44 130 280 30 13.6 I-day Comparative Example 3 A 8 4 0.1 119 242 28 12.1 > 30 days Comparative Example 4 A 8 4 0.8 120 243 29 12.5 > 30 days Comparative Example 5 A 22 15 0.45 105 235 28 12.4 > 30 days Comparative Example 6 A 54 2 0.35 100 223 27 12.3 > 30 days (13) (13) 1341870 A test plate was produced under the manufacturing conditions shown in Table 2 (Comparative Examples) to 6 with the melt having the composition shown in Table]. The test panels prepared were evaluated by performing measurements of the same items as in Examples 1 to 3, and the measurement results are shown in Table 3 (Comparative Examples) to 6). Regarding the examples] to 3 'M g content of appropriate 3.4%, the test plate includes fine recrystallized particles and intermetallic compounds having a surface having an appropriate surface roughness Ra of 0.42 to 0.45 μm. Deep stamping and superior SCC resistance. Namely, with respect to Examples 1 to 3', a melt was introduced into a double belt type casting machine, a flat plate was continuously cast, and the resultant flat plate was wound on a roll. Cooling is carried out during casting so that the area having a thickness of at least a quarter of the thickness below the surface is cooled at a cooling rate of 20 ° C / sec to 200 ° C / sec. In this way, regarding the microstructure in the region of the surface of the final annealed flat plate at a depth of 10 to 30 μm, the intermetallic compound and the like based on Al-(Fe*Mn)-Si can be made fine. 5 microns or less. As a result, peeling between the intermetallic compound and the substrate is hard to occur, even when the final annealed flat plate is deformed, and a flat sheet having superior press formability can be produced. Since the size of the intermetallic compound is relatively small, and in addition, the number of units per unit increases, the concentration of the nucleation sites of the re-agglomerated crystal grains also increases. As a result, the recrystallized particle size becomes a relatively small 15 μm or less 'and thus, a flat plate having superior press formability is provided. Furthermore, when the roller to be used in cold rolling is polished by a honing machine, by controlling the surface roughness of the roll in the range of 0.8 μm of R a 0.2, -18-(14) 1341870 can finally The surface roughness of the annealed flat plate becomes within a limited range of R a 0 · 2 to 0 · 7 , and thus, the surface shape of the final annealed plate has a function to uniformly retain the low-viscosity lubricant used in the forming, Further improve the press formability. On the other hand, in Comparative Example 1, since the Mg content was 3.0%, all of the ultimate tensile strength and elongation were insufficient, and the deep drawability was exhibited. In Comparative Example 2, since the Mg content was as high as 4 · All of the ultimate tensile strength and elongation were good, but no SCC resistance was exhibited. In Comparative Example 3, the surface roughness Ra was as low as 0.] μm. This surface was smoother than the surfaces of Examples] to 3, but exhibited no deep drawing property. In Comparative Example 4, the surface roughness Ra was 3 μm higher, and thus the surface thereof was thicker than the surfaces of Examples 1 to 3 and exhibited poor deep drawability. In Comparative Example 5, a type of d C casting material was used. Since the cooling rate during the production was relatively low, the recrystallized particles and the gold compound contained therein were slightly thicker than those in Examples 1 to 3, and exhibited poor deep drawing properties. In Comparative Example 6, a two-roll casting material was used in which the cooling rate during casting was too high, and the intermetallic compound was finer than that in the case of 3, and the recrystallized particles were coarse and exhibited poor compressibility. The aluminum alloy flat embryo obtained by casting in a double belt casting machine is wound on a roll as described above, and the flat embryo is cold-rolled by a milk I having a surface roughness of Ra 〇〇 8 μm and then, Annealing makes the gold milled micro-cells low, 5% poor. Good, good I 0.8, and between the casts. From, Example 1 deep-drawing straight. 2 to inter- -19- (15) (15) 1341870 The size of the compound becomes 5 microns or less, and the surface of the final annealed plate is deep below the surface of the film. The size of the recrystallized particles in the region becomes [5 μm or less], and the surface roughness becomes R a 0.2 to 0.7 μm. As a result, an aluminum alloy sheet having excellent press formability and stress corrosion crack resistance can be produced.
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