TW200404904A

TW200404904A - Structural Cr-steel and method for manufacturing the same

Info

Publication number: TW200404904A
Application number: TW092124190A
Authority: TW
Inventors: Takumi Ujiro; Hiroki Ota; Osamu Furukimi; Takashi Shiokawa
Original assignee: Jfe Steel Corp
Priority date: 2002-09-03
Filing date: 2003-09-02
Publication date: 2004-04-01
Also published as: TWI306123B; CN1678766A; WO2004022808A1; DE60326247D1; CN1303242C; KR100665128B1; US20050241737A1; EP1538230B1; KR20050057106A; EP1538230A4; EP1538230A1

Abstract

The present invention provides structural Cr-steel, having excellent low temperature toughness and crashworthiness, which is moderately priced than stainless steel and has sufficient corrosion resistance. To be more concrete, the present invention provides structural Cr-steel and method of manufacturing the same. In that, the Cr-steel contains, by mass%, 0.002 to 0.02% of C, 0.002 to 0.2% of N, 0.05 to 1.0% of Si, 0.05 to 1.0% of Mn, 0.04% or less of P, 0.02% or less of S, 0.001 to 0.1% of Al, 6.0 to 10.0% of Cr and further contains 0.1 to 1.0% of Cu, or contains furthermore at least one element selected from the group consisting of 0.1 to 1.0% of Ni and 0.1 to 1.0% of Mo, or contains moreover, at least one element from the group consisting of 0.005 to 0.10% of Nb and 0.005 to 0.20% of V, and the balance being Fe and incidental impurities, wherein Cr concentration at a steel sheet surface is a value of Cr concentration inside the steel sheet -1% or more.

Description

200404904 玖、發明說明：【發明所屬之技術領域】本發明係關於一種構造用CI·鋼，特別是關於一種成為冷凍貨櫃用C r鋼、低溫韌性和撞擊特性良好並且更加便宜於沃斯田鐵系不銹鋼而且耐蝕性也變得充分之構造用C r 鋼。【先前技術】近年來，隨著每個人之飲食生活之提升，同時，冷凍貨櫃之需求也急劇地增加。冷凍貨櫃係主要對於食品來進行遠距離輸送，因此，在使用作為其構成構件之鋼材，要求：耐蝕性和低溫韌性皆良好、在承受撞擊時不容易打開孔洞、不產生斷熱性能之降低。在冷凍貨櫃所使用之構件，大致分成為骨材、外貼材、内貼材。内貼材係冷軋退火板，幾乎是不進行塗裝而進行使用之情況，並且，要求低溫韌性高，因此，作為鋼材係大多是使用成為沃斯田鐵系不鎮鋼且藉由 JIS(Japanese Industrial Standard 、以下簡稱為J I S ) G 4 3 0 5所規定之S U S 3 0 4之情況。該S U S 3 0 4係低溫韌性良好並且延伸大、降伏比（降伏應力/抗拉強度）小而且加工硬化指數大，因此，成為在撞擊時不容易打開孔洞且撞擊特性良好之不銹鋼。但是，在變得昂貴之方面，有大缺點產生。相對於此，骨材或外貼材用途之鋼材係以塗裝，作為前提。作為外貼材係使用冷軋退火板，在高級冷凍貨櫃，使用成為沃斯田鐵系不銹鋼之S U S 3 0 4，但是，由於成本高，因此，也使用藉由JIS G 4305所規定之稱為 6 312/發明說明書(補件)/92-11/92124190 200404904 S U S 4 1 0 L或S U S 4 1 0 S且含有大約1 1 % C r之肥粒鐵系或麻留田鐵系不錄鋼。骨材係使用熱軋退火板，大多使用減低c 或N之1 1 % C r之麻留田鐵系不銹鋼。作為使用在貨櫃材之1 1 % C r鋼係例如揭示在日本專利特公昭51 -13463號公報，藉由含有Cr:10〜18wt% 、Ni: 0.1 〜3.4wt% 、Si: l.Owt% 以下及 Μη: 4.0wt% 以下並且減低至C: 0.03wt%以下、N: 0.02wt%以下而且在熔接熱影響部來生成粗***留田鐵組織而提高熔接熱影響部之延性和勃性之性能之熔接構造用麻留田鐵系不銹鋼。此外，在日本專利特公昭5 7 - 2 8 7 3 8號公報，揭示：藉由含有C r : 10〜13.5wt% 、 Si: 0.5wt% 以下及 Μη: 1.0〜3.5wt% 並且在減低至C : 0 . 0 2 w t %以下、N : 0 , 0 2 w t %以下後而還限制N i在未滿0 . 1 w t %以便不需要熔接前後之預熱、後熱並且熔接部之韌性及加工性良好之構造用麻留田鐵系不銹鋼。該鋼係正如揭示在熔接學會誌、v ο 1 . 5 7 (第5 7 冊）（1 9 8 8 )、N 〇 · 6、P · 4 3 2，適用作為以海上貨櫃之框材為首之各種構造用構件。此種1 1 % C r不銹鋼係比較便宜，大多使用作為貨櫃之骨材或外貼材用之鋼材。比起成為沃斯田鐵系不銹鋼之S U S 3 0 4，對於藉由低溫韌性、所謂耐撞擊性變差之缺點克服、或Cr量之減低或者是熱軋板之退火省略等而還能夠更加達到成本降低之技術上之開發上的期待係變大。相對於此種課題，在日本專利特開平1 1 - 3 0 2 7 9 5號公報，揭示：調整成分成為含有Cr: 8〜16% 、Si: 0.05〜 312/發明說明書(補件)/92-11/92124190 200404904 1.5% 、 Μη: 0.05〜1.5% 並且成為 c: 0.005〜0.1% 、 N: 0 · 0 5 %以下、（C + N ) : 〇 .丨％以了而且在熔接熱影響部來形成體積率5 0 %以上之麻留田鐵之建築構造用肥粒鐵系不銹鋼。但是，揭示於日本專利特開平丨丨—3 〇 2 7 9 5號公報之鋼係除了無法得到用於冷凍貨櫃所使用之充分之低溫韌性以外’還以仍然成為熱軋或者是還在進行熱處理、酸洗後之狀態下之使用，來作為前提，無法施加對於進行塗裝後之财钱性之考量。，揭示：藉 0.05-1.5 此外，在日本專利特開平丨丨—3 〇 2 7 3 7號公報由將含有 Cr: 8 〜16 % 、Si: 0.05 〜1.5 % 、Μη % 及 Ni: 0·05〜1% 並且成為 c: 0.005〜0.1% 、 Ν: 005 %以下、（C+N): 0.1%以下之鋼來加熱至11〇〇〜125〇〇c 而且在8 0 0 °C以上結束熱軋、在7 0 0 °C以下進行盤捲、使得後面之冷卻速度成為5 °C /分鐘以下以便於省略熱札板之退火的技術；但是，該技術係也以仍然成為熱札或者是還在進行熱處理、酸洗後之狀態下之使用，來作為前提，無法施加對於進行塗裝後之耐蝕性之考量。此外，日本專利特願2 0 0 3 - 1 4 1 4 6 2號（相料處> # ，出河應之歐洲專利之申請案號03015110.4、申請日：2003车7 B Q 、千7月3曰）係本案發明者們之所開發之技術，但是，提議.&私# 执•月b夠稭由將含有 Cr:8mass(質量）°/。以上、lOmass(質量思；/〇以下、S i : 0.01 〜l.Omass(質量）％、Μη: 0.01 〜0.3〇niass(質旦）％200404904 发明 Description of the invention: [Technical field to which the invention belongs] The present invention relates to a structural CI · steel, in particular to a Cr steel for refrigerated containers, which has good low temperature toughness and impact characteristics and is cheaper than Vostian Iron Cr steel is a stainless steel structure and has sufficient corrosion resistance. [Previous Technology] In recent years, with the improvement of everyone's dietary life, at the same time, the demand for refrigerated containers has also increased dramatically. Refrigerated containers are mainly used for long-distance transportation of food. Therefore, the use of steel as its constituent components requires good corrosion resistance and low temperature toughness. It is not easy to open holes when subjected to impact, and does not cause a reduction in thermal insulation performance. The components used in refrigerated containers are roughly divided into aggregates, exterior laminates, and interior laminates. The inner-clad cold-rolled annealed sheet is used almost without coating, and requires low-temperature toughness. Therefore, as a steel system, it is mostly used as a Vostian iron-based ballast steel and is based on JIS ( Japanese Industrial Standard (hereinafter referred to as JIS) G 4 3 0 5 SUS 3 0 4 This S U S 3 0 4 series has good low temperature toughness, large elongation, low yield ratio (fall stress / tensile strength), and a large work hardening index. Therefore, it is a stainless steel that is not easy to open holes during impact and has good impact characteristics. However, there are major disadvantages in terms of becoming expensive. On the other hand, steel materials used for aggregates or exterior materials are pre-painted. Cold rolled annealed sheet is used as the exterior material, and SUS 304, which is made of Vostian iron series stainless steel, is used in high-grade refrigerated containers. However, due to the high cost, it is also used as specified by JIS G 4305. 6 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904 SUS 4 1 0 L or SUS 4 1 0 S and containing about 11% Cr of ferrous iron or Maruta iron does not record steel. Aggregate materials use hot-rolled annealed sheets, and most of them use Asari stainless steel which reduces c or N by 11% Cr. As a 11% Cr steel system used in container materials, for example, it is disclosed in Japanese Patent Publication No. 51-13463, and contains Cr: 10 to 18% by weight, Ni: 0.1 to 3.4% by weight, and Si: 1.0% by weight. The following and Mη: 4.0wt% or less and reduced to C: 0.03wt% or less, N: 0.02wt% or less and in the welding heat-affected part to generate a crude hemp ryoda iron structure to improve the ductility and robustness of the welded heat-affected part Maruta iron stainless steel is used for the welding structure. In addition, in Japanese Patent Publication No. 5 7-2 8 7 3 8, it is disclosed that by containing C r: 10 to 13.5 wt%, Si: 0.5 wt% or less, and Mn: 1.0 to 3.5 wt% and reducing it to C: 0. 2 wt% or less, N: 0, 0 2 wt% or less, and Ni is limited to less than 0.1 wt% so that preheating and postheating before and after welding and the toughness of the welded part and Maruta iron stainless steel for structural use with good workability. This steel system, as disclosed in the Journal of Welding Society, v ο 1. 5 7 (Vol. 57) (19 8 8), N 0.6, P 4 32, is suitable for use as the frame material for marine containers. Various structural members. This 11% Cr stainless steel is relatively cheap, and it is mostly used as steel for the container's aggregate or exterior. Compared with SUS 304, which is a Vostian iron-based stainless steel, it can be achieved by the low temperature toughness, the so-called poor impact resistance, the reduction of Cr content, or the omission of annealing of hot-rolled sheet. Expectations for technical development of cost reduction are increasing. In response to such a problem, in Japanese Patent Laid-Open No. 1 1-3 0 2 7 9 5, it is disclosed that the adjusting component contains Cr: 8 to 16%, Si: 0.05 to 312 / Invention Specification (Supplement) / 92 -11/92124190 200404904 1.5%, Μη: 0.05 ~ 1.5% and become c: 0.005 ~ 0.1%, N: 0. 05% or less, (C + N): 〇. 丨% and it is in the heat affected part of welding To form a ferrous iron-based stainless steel for the construction of Maruta Iron with a volume ratio of 50% or more. However, the steel system disclosed in Japanese Patent Laid-Open No. 丨丨 3 〇 2 705, in addition to failing to obtain sufficient low-temperature toughness for refrigerated containers, is still hot rolled or heat-treated. 2. Use in the state after pickling, as a premise, it is not possible to impose considerations on the wealth after painting. Revealed: Borrowed from 0.05-1.5 In addition, in Japanese Patent Laid-Open No. 丨丨 3 〇 2 7 3 7 will contain Cr: 8 ～ 16%, Si: 0.05 ～ 1.5%, Μη%, and Ni: 0.05 ~ 1% and become c: 0.005 ~ 0.1%, N: 005% or less, (C + N): 0.1% or less of steel to heat to 1100 ~ 125〇c and finish the heat above 8 0 ° C Rolling, coiling below 700 ° C, so that the subsequent cooling rate is 5 ° C / min or less in order to omit the annealing of the hot stamping plate; however, this technology is still a hot stamping or As a premise, heat treatment and pickling can not be used in consideration of corrosion resistance after coating. In addition, Japanese Patent Application No. 2000-3-1 4 1 4 6 2 (Phase Material >#, Dekayo's European Patent Application No. 03015110.4, Application Date: 2003 Car 7 BQ, July 3 Said) is a technology developed by the inventors of this case, however, it is proposed that & 私 # # • Monthly, it will contain Cr: 8mass (quality) ° /. Above, lOmass (quality thinking; / 〇 or less, S i: 0.01 to l.Omass (mass)%, Mn: 0.01 to 0.3〇niass (mass denier)%

Cu:0.01 〜l.Omass(質量）％、Ni :0.01 〜]n 1 · Umass(質量） %及V: 0.01〜0.20mass(質量）％之鋼來加熱至丨1〇〇 312/發明說明書(補件)/92-11/92124190 200404904 1 2 8 0 °C、在超過9 3 0 °C之溫度結束熱軋、在超過8 1 0 °C之溫度進行盤捲後、使得8 0 0〜4 0 0 °C之冷卻速度成為2 °C /分鐘以下以便於省略熱軋板退火之構造用鋼板。但是，關於藉由日本專利特願2 0 0 3 - 1 4 1 4 6 2號所造成之鋼材係無法得到以在熱軋後、仍然進行酸洗之狀態下、不施加塗裝而進行使用來作為前提之技術，仍然無法得知藉由在本發明成為重要之酸洗量控制所造成之表面性狀之改善以及隨著這個而造成之塗裝後之耐蝕性改善之意見。有鑑於前述先前技術之現狀，本發明之目的係提供一種低溫韌性和耐撞擊性良好並且更加便宜於沃斯田鐵系不銹鋼而且耐蝕性也變得充分之構造用Cr鋼、特別是冷凍貨櫃用Cr鋼。冷凍貨櫃用鋼材係在幾乎所有之情況下，由耐蝕性提升或特別是創意性之觀點來看的話，則在表面，施加各種塗裝。因此，塗裝後之耐蝕性係變得重要，根據本發明者們之調查研究，結果，在塗裝後、造成橫切之試驗片之鹽水喷霧試驗，必須要有不產生1 0 0 0小時之顯著流動銹之耐蝕性。【發明内容】Cu: 0.01 ~ l. Omass (mass)%, Ni: 0.01 ~) n 1 · Umass (mass)% and V: 0.01 ~ 0.20mass (mass)% of steel to be heated to 1003 / invention specification ( (Supplement) / 92-11 / 92124190 200404904 1 2 8 0 ° C, finish hot rolling at a temperature exceeding 9 3 0 ° C, coil after coiling at a temperature exceeding 8 1 0 ° C, so that 8 0 0 ~ 4 The cooling rate at 0 0 ° C is 2 ° C / min or less in order to omit the structural steel sheet for hot-rolled sheet annealing. However, the steel material caused by Japanese Patent Application No. 203-1 4 1 4 6 2 cannot be obtained and used after being hot-rolled and still in the state of pickling without coating. As a prerequisite technology, the improvement of the surface properties caused by the pickling amount control which became important in the present invention, and the improvement of the corrosion resistance after coating caused by this are still not known. In view of the foregoing state of the art, an object of the present invention is to provide a structural Cr steel, particularly a refrigerated container, which is excellent in low-temperature toughness and impact resistance, is cheaper than Vostian iron-based stainless steel, and has sufficient corrosion resistance. Cr steel. In almost all cases, the steel for refrigerated containers has various coatings applied to the surface from the viewpoint of improving corrosion resistance or, in particular, being creative. Therefore, the corrosion resistance after coating becomes important. According to the investigation and research by the inventors, after the coating, the salt spray test of the test piece that caused cross-cutting must be performed without generating 1 0 0 0 Corrosion resistance of significant flowing rust for hours. [Summary of the Invention]

本發明者們係為了解決前述課題，調查許多以C r鋼作為基礎而添加元素對於前述各種特性所造成之影響，結果，發現到：可以藉由使得C r量成為6 . 0〜1 0 . 0 % ，C、N 量成為0 . 0 2 %以下之作為構造用C r鋼、特別是同時達成貨櫃用鋼之所需要之耐蝕性和韌性、耐撞擊性雙方，能夠 ^ 312/發明說明書(補件)/92-11/92124190 200404904 更加便宜於沃斯田鐵系不銹鋼而進行製造，並且，可以省略熱軋板之退火，能夠更進一步、更加便宜地進行製造。此外，還得到控制隨著熱軋板之脫銹皮所帶來之鋼板表面除去量而同時達成脫銹皮後之鋼板表面之性狀和耐蝕性雙方，作為改善塗裝後之耐蝕性之手段係變得重要之意見。根據此種意見而以致於達成成為以下要旨構成之本發明。也就是說，本發明之構造用Cr鋼，係含有mass(質量） % 之 C: 0.0 0 2 - 0.0 2 % 、N ： 0.0 0 2 - 0.0 2 % 、Si: 0.05- 1.0% 、Μη: 0.05-1.0% 、Ρ ： 0. 0 4 % 以下、S ： 0.02% 以下、A 1 · 0.001 〜0.1% 、Cr: 6. 0 ~ 1 0 . 0 % ，由殘餘部 F e 和不可避免之不純物所構成，鋼板表面之Cr濃度成為鋼板内部之C r濃度-1 %以上。此外，本發明之構造用C r鋼，係在前述發明鋼，還含有 mass(質量）％之 Cu: 0 . 1 ~ 1 . 0 % 。此外，本發明之構造用C r鋼，係在前述發明鋼，還含有由11^55(質量）％之“：0.1〜1.0%、肘〇:0.1〜1.0%中之所選擇出之1種或2種以上。此外，本發明之構造用C r鋼，係在前述發明鋼，還含有由 mass(質量）％之 Nb · 0.005 〜0.10% 、V: 0. 005~ 0. 20 %中之所選擇出之1種或2種。本發明之構造用Cr鋼熱軋鋼板之製造方法，其特徵為：藉由再加熱後之熱軋而使得含有mass(質量）％之C:0. 002 -0.02% > N ： 0 . 0 0 2 ~ 0 . 0 2 % 、S i : 0· 0 5 〜1 · 0 % 、Μ η : 0 . 0 5 〜1.0% 、Ρ: 0·04% 以下、S: 0.02% 以下、Α1: 0.001 〜 10 312/發明說明書(補件)/92-11 /92124190 200404904 0 . 1 % 、C r : 6 . 0〜1 0 . 0 %且由殘餘部F e和不可避免之不純物所構成之鋼素材，成為鋼帶，接著，在進行脫銹皮處理之熱軋鋼板之製造步驟，藉由脫銹皮處理而除去鋼板表面 10 〜200// m 〇此外，本發明之構造用Cr鋼冷軋鋼板之製造方法，係在前述發明鋼板之製造方法，在進行前述脫銹皮處理後，進行冷軋、熱軋退火和酸洗。此外，本發明之構造用C r鋼板之製造方法，係在前述發明鋼板之製造方法，使得前述鋼素材還含有Cu: 0.1〜 1.0% 。此外，本發明之構造用C r鋼板之製造方法，係在前述發明鋼板之製造方法，使得前述鋼素材還含有由Ni: 0.1 〜1.0%1〇:0.1〜1.0%中之所選擇出之1種或2種以上。此外，本發明之構造用C r鋼板之製造方法，係在前述發明鋼板之製造方法，使得前述鋼素材還含有Nb: 0.005 〜0.10 % 、V:0. 005〜0.20 %中之所選擇出之1種或2種。此外，本發明之構造用Cr鋼係前述發明鋼係成為冷凍貨櫃用。此外，本發明之構造用C r鋼熱軋鋼板之製造方法，係在前述發明鋼板之製造方法，使得前述構造用Cr鋼板成為冷凍貨櫃骨材用。此外，本發明之構造用Cr鋼冷軋鋼板之製造方法，係在前述發明鋼板之製造方法，使得前述構造用Cr鋼板成為冷柬貨櫃外貼材用。 11 312/發明說明書(補件)/92-11 /92124190 200404904 此外，本發明之冷凍貨櫃，係使用前述發明鋼或藉由前述發明方法所製造之C r鋼板，藉由成形和熔接而進行加工，並且，在該鋼板表面，具有乾燥膜厚10//m以上之塗膜。此外，本發明之構造用Cr鋼係使得前述發明鋼成為土木、建築構造用。此外，本發明之構造用Cr鋼熱軋鋼板之製造方法，係使得前述發明鋼成為土木、建築構造用。此外，本發明之構造用Cr鋼冷軋鋼板之製造方法，係使得前述發明鋼成為土木、建築構造用。【實施方式】以下，就本發明而具體地進行說明。首先，在本發明，就合金之成分組成限定在前述範圍之理由而進行說明。此外，成分含有量之單位係m a s s % ，以後，簡記為％。 (1)C ： 0.0 0 2 - 0.0 2 % C係為了提高塗裝後之耐蝕性，因此，最好是越低越好。這個係根據隨著碳氮化物之析出所造成之脫鉻層之生成之抑制。但是，在未滿0. 0 0 2 % ，強度變得不足，但是，在超過0 . 0 2 % ，韌性、延性變得不足而使得耐撞擊性降低。在本發明鋼，使得C減低至0 . 0 2 %以下係變得重要。此外，也可以藉由使得C量成為0 . 0 2 %以下而省略熱軋板之退火。因此，C含有量係成為0 . 0 0 2〜0 . 0 2 % 。由塗裝後之耐 I虫性改善之方面來看的話，C含有量之理想範圍係最好是 12 312/發明說明書(補件)/92-11 /92124190 200404904 0 · 0 0 3〜0 · 0 1 3 % ，更加理想是0 · 0 0 3〜0 · 0 0 8 % ，最佳理想是Ο · Ο Ο 3〜Ο . Ο Ο 5 %之範圍。 (2 ) Ν : 0.0 0 2 - 0.0 2 % Ν係也相同於C，為了提高塗裝後之耐蝕性，因此，最好是越低越好。但是，在未滿0. 0 0 2 % ，強度變得不足，但是，在超過0 . 0 2 % ，韌性、延性變得不足而使得耐撞擊性降低。在本發明鋼，使得N也減低至0 . 0 2 %以下係變得重要。此外，也可以藉由使得N量成為0. 0 2 %以下而省略熱軋板之退火。因此，N含有量係成為0 . 0 0 2〜0 . 0 2 % 。由塗裝後之耐蝕性改善之方面來看的話，N含有量係最好是 0.0030〜0.0060% 。 (3 ) S i : 0.05-1.0% S i係作為脫氧劑之有用元素，但是，其含有量係在未滿 0.05%，無法得到充分之脫氧效果，因此，必須成為0 . 0 5 % 以上。但是，在S i含有量成為超過1 . 0 %時，勒性、延性變得不足而使得耐撞擊性降低。因此，S i含有量成為0 . 0 5 〜1 . 0 % 。由低溫韌性改善之方面來看的話，則理想添加量之範圍係0 . 1〜0 . 5 % 。 (4)Mn ： 0.05-1.0% Μ η係也相同於S i，作為脫氧劑之有用元素，但是，其含有量係在未滿0 . 0 5 %，無法得到充分之脫氧效果，因此，必須成為0 . 0 5 %以上。但是，在Μ η含有量成為超過1 . 0 % 時，Μ n S介在物係增加而使得耐蝕性降低。因此，Μ η含有量成為0.05〜1.0% 。由塗裝後之耐姓性改善之方面來看 13 312/發明說明書(補件)/92-11/92124190 200404904 的話，則理想含有量之範圍係0 . 1 0〜0 . 3 0 % 。 (5 ) Ρ : Ο . Ο 4 % 以下 Ρ係不僅惡化韌性、延性等之機械性質並且也對於耐蝕性來說成為有害元素，特別是在Ρ含有量超過0. 0 4 %時，其影響變得顯著，因此，限制Ρ含有量在0. 0 4 %以下。特別是在塗裝後而需要高耐蝕性之情況下，最好是使得Ρ含有量成為0.02%以下。 (6)S ： 0.02% 以下 S係結合於Μη而形成MnS，成為初期生錄起點。此外，S 係偏析於結晶粒界而促進粒界脆性之有害元素，因此，最好是極力降低。特別是在S含有量超過0 . 0 2 %時，其壞影響變得顯著，因此，限制S含有量在0. 0 2 %以下。特別是在塗裝後而需要高耐蝕性之情況下，最好是使得S含有量成為0 . 0 0 6 %以下。 (7 ) A 1 : 0.001-0.1% A 1係作為脫氧劑之有用元素，此外，對於氧化物進行球狀化，具有改善在彎曲加工時之延性之效果，但是，其含有量係在未滿0 . 0 0 1 % ，無法得到充分之前述效果，因此，必須成為0 . 0 0 1 %以上。但是，在A 1含有量超過0. 1 %時，介在物變多而使得耐蝕性降低。因此，A 1含有量成為0 . 0 0 1 〜0. 1 % 。此外，在含有許多A1時，恐怕介在物變多而導致機械性質之惡化，因此，由熱軋板加工性之觀點來看的話，A 1含有量之上限係最好是成為0 . 0 5 % 。 (8 ) C r : 6 . 0 〜1 0 . 0 0/〇 14 312/發明說明書(補件)/92-11/92124190 200404904 C r係為了確保作為本發明成為對象之冷凍貨櫃材之必要之耐蝕性而不可或缺之元素。冷凍貨櫃材係塗裝外裝而進行使用，因此，並無要求像S U S 3 0 4左右之耐蝕性，即使是這樣’在未滿6. 0 % ’也無法確保财餘性。但是’在C r 量超過1 0 . 0 %時，韌性、延性變得不足而使得耐撞擊性降低。在本發明中，發現在C r含有量6. 0〜1 0 . 0 %使得同時達成作為冷凍貨櫃材之必要之耐蝕性和韌性、耐撞擊性雙方，此係成為重要意見。此外，也可以藉由使得Cr量成為 1 0 . 0 % 以下而省略熱軋板之退火。此外，在省略熱軋板之退火時，若要使之具備充分之低溫韌性，添加量係最好是成為6 . 0〜9 . 5 %之範圍。更加理想之範圍係6 . 0〜9 · 0 % 。以上係本發明之基本化學成分，但是，還為了提高耐蝕性，因此，可以添加以下之元素。 (9)Cu ·· 0.1-1.0% C u係用以減低腐蝕速度而提高耐蝕性之有用元素，即使是對於間隙腐蝕之抑制也能有效地發揮作用。在本發明成為問題之塗裝後之耐蝕性，在塗裝呈部分剝離之部分之間隙構造之腐蝕係成為問題，因此，在塗裝後而需要高耐蝕性之情況下，最好是添加C u。但是，在未滿0. 1 %之含有量，在其效果極微，另一方面，在其含有量超過1.0%時，會有延性和耐撞擊性降低之傾向發生，並且，容易發生在熱軋之熱裂。因此，c U含有量係最好是成為0 . 1〜1 . 0 % 。此外，由熱裂防止和加工性之觀點來看的話，添加量之上限係最好是成為0 . 7 % 。 15 312/發明說明書(補件)/92-11/92124190 200404904 (1 0 ) N i ： 0.1-1.0% N i係也減低腐餘速度而提高财#性。此外，也是有效於提高韌性之成分。但是，在未滿0. 1 %之含有量，在這些效果極微，另一方面，N i係非常昂貴之元素，在其含有量超過1 . 0 %時，成為成本升高，因此，N i含有量係最好是成為0 . 1〜1 . 0 % 。此外，成為不導致素材之硬質化或成本上升之範圍，含有量之上限係最好是成為0.5% 。 (1 1 ) Μ 〇 : 1 · 0 % 以下In order to solve the aforementioned problems, the present inventors investigated the effects of many elements added on the basis of Cr steel on the aforementioned various characteristics, and found that: the amount of Cr can be made 6.0 to 1 0. 0%, the amount of C and N becomes 0.22% or less. As the steel for structural use, especially the steel for container use, the corrosion resistance, toughness, and impact resistance required can be achieved at the same time. 312 / Invention Specification ( (Supplement) / 92-11 / 92124190 200404904 It is cheaper to manufacture than Vostian iron-based stainless steel, and the annealing of hot-rolled sheet can be omitted, and it can be manufactured further and cheaper. In addition, it is also possible to control both the properties of the steel sheet surface after descaling and the corrosion resistance along with the amount of steel sheet surface removal caused by the descaling of the hot-rolled sheet, as a means to improve the corrosion resistance after coating. Opinion that becomes important. Based on such an opinion, the present invention having the following gist has been achieved. In other words, the Cr steel for construction of the present invention contains C: 0.0 0 2-0.0 2%, N: 0.0 0 2-0.0 2%, Si: 0.05- 1.0%, and Mn: 0.05. -1.0%, P: 0.4% or less, S: 0.02% or less, A 1 · 0.001 to 0.1%, Cr: 6. 0 to 10.0%, which is caused by the residual Fe and unavoidable impurities The Cr concentration on the surface of the steel plate is equal to or higher than the C r concentration in the steel plate by -1%. In addition, the Cr steel used in the structure of the present invention is the steel of the aforementioned invention, and further contains Cu: 0.1 to 1.0% by mass. In addition, the C r steel for structural use of the present invention belongs to the aforementioned invention steel, and also contains one selected from 11:55 (mass)% ": 0.1 to 1.0%, and elbow 0: 0.1 to 1.0%. Or two or more types. In addition, the C r steel for the structure of the present invention belongs to the aforementioned invention steel, and also contains Nb by mass (mass)% of 0.005 to 0.10%, and V: 0.005 to 0.20%. One or two selected. The manufacturing method of the Cr steel hot-rolled steel sheet for the structure of the present invention is characterized by: by hot rolling after reheating, so that C: 0.002 is contained in mass (mass)% -0.02% > N: 0. 0 0 2 to 0. 2%, Si: 0 · 0 5 to 1 · 0%, M η: 0. 5 to 1.0%, P: 0. 04% or less , S: 0.02% or less, A1: 0.001 to 10 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904 0. 1%, C r: 6.0 to 1 to 0.0% and the residual portion F e The steel material consisting of unavoidable impurities and steel becomes a steel strip. Next, in the manufacturing step of a hot-rolled steel sheet that is subjected to descaling treatment, the surface of the steel plate is removed by descaling treatment. 10 ~ 200 // m 〇 In addition, Cr steel cold-rolled steel sheet for construction of the present invention The manufacturing method is the manufacturing method of the aforementioned steel sheet of the invention, and the cold rolling, hot rolling annealing, and pickling are performed after the aforementioned descaling treatment. In addition, the manufacturing method of the Cr steel sheet for the structure of the present invention is the aforementioned invention The manufacturing method of the steel plate is such that the aforementioned steel material also contains Cu: 0.1 to 1.0%. In addition, the manufacturing method of the Cr steel plate for the structure of the present invention is based on the manufacturing method of the aforementioned steel plate of the invention, so that the aforementioned steel material also contains Ni: 0.1 to 1.0% 10: one to two or more selected from 0.1 to 1.0%. In addition, the manufacturing method of the Cr steel sheet for use in the structure of the present invention is the manufacturing method of the steel sheet of the aforementioned invention, so that the aforementioned steel The material also contains one or two of Nb: 0.005 to 0.10% and V: 0.005 to 0.20%. In addition, the Cr steel for the structure of the present invention is a steel container of the aforementioned invention and is used for a refrigerated container. The method for manufacturing the Cr steel hot-rolled steel sheet for the structure of the present invention is based on the method for manufacturing the steel sheet of the present invention, so that the aforementioned Cr steel sheet for the structure is used as a refrigerator container. In addition, the Cr steel cold-rolled steel sheet for the structure of the present invention Of The manufacturing method is based on the manufacturing method of the aforementioned invention steel plate, so that the aforementioned structural Cr steel plate is used as an external covering material for a cold Cambodian container. 11 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904 In addition, the refrigerated container of the present invention It uses the aforementioned invention steel or the Cr steel plate manufactured by the aforementioned invention method to be processed by forming and welding, and the surface of the steel plate has a coating film with a dry film thickness of 10 // m or more. In addition, the Cr steel system for construction of the present invention makes the aforementioned steel of the present invention useful for civil and building construction. In addition, the method for manufacturing a Cr steel hot-rolled steel sheet for construction according to the present invention is such that the aforementioned invention steel is used for civil and building construction. In addition, the method for manufacturing a cold-rolled steel sheet for structural Cr steel according to the present invention is such that the steel according to the present invention is used for civil engineering and building construction. [Embodiment] Hereinafter, the present invention will be specifically described. First, in the present invention, the reason why the component composition of the alloy is limited to the aforementioned range will be described. In addition, the unit of the component content is ma s s%, and it is abbreviated as%. (1) C: 0.0 0 2-0.0 2% C is for the purpose of improving the corrosion resistance after painting. Therefore, the lower value is better. This is based on the suppression of the formation of a dechromized layer due to the precipitation of carbonitrides. However, when it is less than 0.02%, the strength becomes insufficient. However, when it exceeds 0.02%, the toughness and ductility become insufficient and the impact resistance decreases. In the steel of the present invention, it is important to reduce the C to 0.02% or less. In addition, the annealing of the hot-rolled sheet can be omitted by setting the amount of C to be 0.02% or less. Therefore, the C content is 0.02 to 0.22%. From the viewpoint of improving the resistance to I insects after painting, the ideal range of the C content is preferably 12 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904 0 · 0 0 3 ~ 0 · 0 1 3%, more preferably 0 · 0 0 3 ~ 0 · 0 0 8%, and the best ideal is in the range of Ο · Ο Ο 3 ~ Ο. Ο Ο 5%. (2) Ν: 0.0 0 2-0.0 2% Ν is also the same as C. In order to improve the corrosion resistance after painting, the lower the better. However, when it is less than 0.02%, the strength becomes insufficient. However, when it exceeds 0.02%, the toughness and ductility become insufficient to reduce the impact resistance. In the steel of the present invention, it is important to reduce N to 0.02% or less. In addition, the annealing of the hot-rolled sheet may be omitted by setting the amount of N to 0.2% or less. Therefore, the N content is set to 0.02 to 0.22%. From the viewpoint of improvement in corrosion resistance after coating, the N content is preferably 0.0030 to 0.0060%. (3) S i: 0.05-1.0% S i is a useful element as a deoxidizing agent. However, its content is less than 0.05%, and a sufficient deoxidizing effect cannot be obtained. Therefore, it must be 0.05% or more. However, when the Si content exceeds 1.0%, the tensile strength and ductility become insufficient, and the impact resistance decreases. Therefore, the Si content is from 0.05 to 1.0%. From the viewpoint of improving the low-temperature toughness, the range of the ideal addition amount is 0.1 to 0.5%. (4) Mn: 0.05-1.0% Mn system is also the same as Si, as a useful element of deoxidizer, but its content is less than 0.05%, it can not get a sufficient deoxidation effect, so it must be It is 0.5% or more. However, when the M η content exceeds 1.0%, M n S increases in the intervening system and decreases the corrosion resistance. Therefore, the M η content is 0.05 to 1.0%. From the aspect of improving the surname resistance after painting 13 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904, the ideal content range is 0.10 to 0.30%. (5) Ρ: 〇. 〇 4% or less P is not only a deterioration of mechanical properties such as toughness, ductility, etc., but also a harmful element for corrosion resistance, especially when the content of P exceeds 0.4%, its influence becomes 0 4% 之间。 Significantly, therefore, limit the P content to 0.04% or less. In particular, when high corrosion resistance is required after coating, it is preferable to make the P content be 0.02% or less. (6) S: 0.02% or less S is bound to Mn to form MnS, which becomes the starting point of initial recording. In addition, since S is a harmful element that segregates at the crystal grain boundary and promotes brittleness of the grain boundary, it is desirable to reduce it as much as possible. In particular, when the S content exceeds 0.22%, its bad influence becomes significant. Therefore, the S content is limited to 0.22% or less. In particular, when high corrosion resistance is required after coating, it is desirable to make the S content be 0.6% or less. (7) A 1: 0.001-0.1% A 1 is a useful element as a deoxidizer. In addition, the spheroidization of oxides has the effect of improving the ductility during bending, but its content is less than 0.01% is not sufficient to obtain the aforementioned effects, so it must be 0.01% or more. However, when the content of A 1 exceeds 0.1%, the intervening substances increase and the corrosion resistance decreases. Therefore, the content of A 1 becomes 0. 0 0 1 to 0.1%. In addition, when a large amount of A1 is contained, there is a fear that mechanical properties deteriorate due to an increase in intervening substances. Therefore, from the viewpoint of hot-rolled sheet processability, the upper limit of the content of A 1 should preferably be 0.05%. . (8) C r: 6.0 to 1.0 0 0 / 〇14 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904 C r is necessary to secure the refrigerated container material targeted by the present invention. Indispensable element for corrosion resistance. The refrigerated container materials are used in exterior coatings. Therefore, no corrosion resistance is required, such as S U S 3 0 4 or less. Even if it is less than 6.0%, the margin cannot be ensured. However, when the amount of C r exceeds 10.0%, the toughness and ductility become insufficient to reduce the impact resistance. In the present invention, it has been found that the Cr content of 6.0 to 1.0% makes it possible to achieve both the corrosion resistance, toughness, and impact resistance necessary for a refrigerated container material at the same time, which becomes an important opinion. In addition, the annealing of the hot-rolled sheet can be omitted by making the amount of Cr less than 10.0%. In addition, when the annealing of the hot-rolled sheet is omitted, in order to have sufficient low-temperature toughness, the addition amount is preferably in a range of 6.0 to 9.5%. A more desirable range is 6.0 to 9 · 0%. The above are the basic chemical components of the present invention. However, in order to improve the corrosion resistance, the following elements can be added. (9) Cu ·· 0.1-1.0% Cu is a useful element for reducing the corrosion rate and improving the corrosion resistance, and can effectively play a role in suppressing interstitial corrosion. Corrosion resistance after coating, which is a problem in the present invention, is a problem in the corrosion structure of the gap structure where the coating is partially peeled off. Therefore, when high corrosion resistance is required after coating, it is preferable to add C. u. However, when the content is less than 0.1%, the effect is extremely small. On the other hand, when the content exceeds 1.0%, the ductility and impact resistance tend to decrease, and it tends to occur in hot rolling. Hot crack. Therefore, the content of c U is preferably set to 0.1% to 1.0%. In addition, from the viewpoint of thermal cracking prevention and workability, the upper limit of the amount added is preferably 0.7%. 15 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904 (1 0) Ni: 0.1-1.0% Ni system also reduces the rate of corruption and improves financial performance. It is also an ingredient effective in improving toughness. However, when the content is less than 0.1%, these effects are extremely small. On the other hand, Ni is a very expensive element. When the content exceeds 1.0%, the cost increases. Therefore, Ni The content is preferably 0.1% to 1.0%. In addition, it is a range that does not cause hardening of materials or increase in cost, and the upper limit of the content is preferably 0.5%. (1 1) 〇: 1.0% or less

Mo係減低腐蝕之發生及腐蝕速度而提高耐蝕性。但是，在未滿0. 1 %之含有量，在其效果極微，另一方面，相同於Ni而為非常昂貴之元素，在其含有量超過1.0%時，成為成本升高，並且，延性也降低，因此，Mo含有量係最好是成為0 . 1〜1 . 0 % 。此外，由所謂耐蝕性和強度、加工性之平衡之觀點來看的話，適合成為0.1〜0.5%之範圍。 (12)Nb ： 0.0 0 5 - 0.1 0 %Mo is used to reduce the occurrence of corrosion and the corrosion rate to improve the corrosion resistance. However, when the content is less than 0.1%, its effect is extremely small. On the other hand, the element that is very expensive, which is the same as Ni, will increase the cost when the content exceeds 1.0%, and the ductility will also increase. As a result, the Mo content is desirably 0.1 to 1.0%. From the viewpoint of the balance between corrosion resistance, strength, and workability, it is suitable to be in the range of 0.1 to 0.5%. (12) Nb: 0.0 0 5-0.1 0%

Nb係在熱軋中，析出成為Nb碳氮化物，具有抑制結晶粒成長之作用，具有使得熱軋後之鋼板結晶粒大幅度地進行微細化之效果。特別是在需要低溫下之韌性之情況下， N b之添加係變得有效。但是，在添加量未滿0 . 0 0 5 %時，在其效果極微，另一方面，在添加超過0. 1 0 %時，熔接部韌性係降低，因此，添加量係成為0 . 0 0 5〜0 . 1 0 % 。由熔接部勃性之方面來看的話，更加理想之添加量上限係成為 0 . 0 6 % 。 (1 3 ) V : 0.0 0 5 -0.20% 16 312/發明說明書(補件)/92-11/92124190 200404904 V係相同於Nb，在熱軋中，以所謂V碳氮化物或V 形式而進行，具有使得熱軋後之鋼板結晶粒進行微細效果，有效於鋼板低溫韌性之改善，但是，在添加量 0. 0 0 5 %時，在其效果極微，另一方面，在添加超過（ %時，相反地成為熔接部或母材韌性降低之原因。因添加量係成為0 . 0 0 5〜0 . 2 0% 。由改善母材韌性之方看的話，更加理想之添加量上限係成為0. 1 5 % 。以上，除了前述各種成分以外，還有Fe及不可避免純物。 (1 4 )鋼板之顯微組織接著，就鋼板之顯微組織而進行敘述。藉由本案技製造之鋼係在實質上，成為肥粒鐵單相組織。在進行盤捲後而進行冷卻之狀態下，也有包含一部分之變韌情況發生，但是，在冷軋退火後之鋼板，實質成為肥單相組織。在本案發明鋼，於進行熱軋後或冷軋退火加工前之狀態，進行不生成硬質麻留田鐵之成分設計一方面，在熔接部，調整低C量及低N量之麻留田鐵成為主體之成分，具有所謂在進行藉由熔接所造成之後也得到充分之低溫韌性之良好特徵。 (1 5 )鋼板之製造方法接著，本發明鋼係藉由以下之製程而進行製造。首在藉由轉爐或電爐等之熔製爐而進行熔製後，將藉由法、A 0 D法、R Η法等之精煉方法而調整成為本發明之組成之炫鋼，藉由連續錄造法或造塊一分塊親軋法， 312/發明說明書(補件)/92-11/92124190 心之化之未滿 ).20 此， S來之不術所熱軋鐵之粒鐵後之。另組織組裝先， V0D 成分來成 17 200404904Nb is precipitated to form Nb carbonitrides during hot rolling, and has the effect of suppressing the growth of crystal grains, and has the effect of greatly refining the crystal grains of the steel sheet after hot rolling. In particular, when toughness at a low temperature is required, the addition system of N b becomes effective. However, when the addition amount is less than 0.05%, the effect is extremely small. On the other hand, when the addition amount exceeds 0.10%, the toughness of the welded part is reduced. Therefore, the addition amount is 0.05. 5 ~ 0. 10%. From the aspect of the welded part's robustness, a more desirable upper limit of the addition amount is 0.06%. (1 3) V: 0.0 0 5 -0.20% 16 312 / Instruction of the Invention (Supplement) / 92-11 / 92124190 200404904 V is the same as Nb. In hot rolling, it is performed in the form of so-called V carbonitride or V. It has a fine effect of making the crystal grains of the steel sheet after hot rolling effective to improve the low-temperature toughness of the steel sheet. However, when the addition amount is 0.05%, the effect is extremely small. On the other hand, when the addition exceeds (% On the contrary, it causes the toughness of the welded part or the base material to decrease. Because the amount of addition is 0. 0 0 5 to 0.20%. From the perspective of improving the base material toughness, a more desirable upper limit of the amount of addition is 0. 15%. Above, in addition to the aforementioned various components, there are Fe and unavoidable pure materials. (1 4) Microstructure of the steel plate Next, the microstructure of the steel plate will be described. The steel manufactured by the present technology In essence, it becomes a single-phase structure of ferrous grains. In the state of cooling after coiling, some toughening occurs, but the steel plate after cold-rolling and annealing actually becomes a single-phase structure of fat. The steel of the invention is hot rolled or cold rolled In the state before the fire processing, the component design of the hard Maruta iron is not carried out. On the one hand, in the welding part, the low-C and low-N Maruta iron is adjusted to become the main component. Good characteristics of sufficient low-temperature toughness are also obtained. (1 5) Steel plate manufacturing method Next, the steel of the present invention is manufactured by the following process. First, after melting in a melting furnace such as a converter or an electric furnace , Will be adjusted into the composition of the present invention by refining methods such as method, A 0 D method, R 等 method, etc., by the continuous recording method or a block-by-block rolling method, 312 / Invention Specification ( (Supplement) / 92-11 / 92124190 The Unsaturated Heart) .20 Therefore, S comes after the hot-rolled iron grains that come from the insult. Another organization and assembly first, the V0D component comes to 17 200404904

為鋼鍵（slab)。接著，加熱該鋼旋，藉由熱軋步驟而成為熱軋鋼板。此外，也可以將鑄造後之鋼錠在冷卻至室溫前，裝入至加熱爐，或者是對於鑄造後之鋼鍵直接地進行熱軋。在進行鋼錠再加熱之情況下之熱軋之鋼鍵再加熱溫度係並無特別限定，但是，為了省略熱軋板之退火步驟，因此，必須使得盤捲溫度變高，結果，鋼錠再加熱溫度係最好是成為1050 °C以上。另一方面，在再加熱溫度超過 1250 °C時，不僅是由於加熱中之鋼鍵表面氧化所造成之損失變多，並且，也有引起鋼錠下垂之問題發生。此外，由於鋼組成，因此，也會有一部分變態成為5肥粒鐵相而損害到在熱間之加工性之情況發生。在熱間粗軋之壓下條件和溫度條件係並無特別限定，但是，最好是進行壓下率3 0 %以上之輥軋至少一次通過。藉由在該強壓下之輥軋而使得鋼板之結晶粒，來進行微細化，改善母材之低溫勒性。由所謂捲盤機盤捲後之軟質化促進之觀點來看的話，在熱軋之精加工溫度成為9 0 0 °C以上、最好是超過9 3 0 °C係變得理想。可以藉由使得在熱軋之精加工溫度成為9 0 0 °C以上而防止由於在a + r之2相區域之輥軋所造成之加工肥粒鐵之導入，並且，由於高度地確保盤捲溫度，因此，可以在盤捲後之冷卻中，抑制硬質麻留田鐵相之生成。由盤捲後之軟質化之觀點來看的話，在熱軋之盤捲溫度成為8 0 0 °C 以上、最好是超過8 1 0 °C係變得理想。在熱軋結束後，在需要強度調整之情況等，可以配合需要而施加熱軋板之退火。在進行熱軋板退火之情況下之溫度係可以進行6 0 0 °C 18 312/發明說明書(補件)/92-11 /92124190 200404904 以上之分批退火或連續退火。分批退火之情況下之退火時間係最好是成為1小時以上。然後，藉由喷砂或酸洗等而除去銹皮及鋼板表面。可以在熱軋後、熱軋退火後或脫銹皮後之鋼板，由於形狀矯正之目的而施加藉由調質輥軋所達成之壓下。 (16)在脫銹皮步驟之鋼板表面之除去量在該脫銹皮步驟之除去量係左右成為本發明著眼之塗裝後之财#性之重要事項。在此，所謂本發明之鋼板表面之除去量1係正如顯示圖4之示意圖，成為由所謂銹皮/鋼板界面2開始之板厚方向之厚度，包含内部氧化層3及脫鉻層4之厚度。在熱軋後或熱軋退火後之鋼板表面上，生成以Fe和Cr之氧化物作為主體之錄皮層5，在外層，形成以Fe作為主體之尖晶石相（spinel structure phase)，在内層，形成以Fe和Cr作為主體之尖晶石相。已經知道：在熱軋盤捲後等之鋼板長時間地曝露於高溫時，隨著接近鋼板側之銹皮層5進行成長而造成Cr優先地進行氧化，由於來不及進行由鋼板内部起之Cr擴散所造成之供應，因此，在銹皮正下方之鋼板側，形成脫鉻層4。在進行脫銹皮後之鋼板表面而殘留脫鉻層4時，耐蝕性係顯著地降低，因此，在脫銹皮步驟，完全地除去鋼板表面之脫鉻層 4係變得重要。在包含1 1 %以上C r之所謂不銹鋼，在前述尖晶石層之更加内側，連續地形成以Cr2〇3作為主體之緻密層，因此，抑制由外部開始而朝向鋼板之氧進入。所以，，脫鉻層4之厚度係由銹皮/鋼板界面開始之至多未滿10 19 312/發明說明書(補件)/92-11/92124190 200404904 // m。但是，正如本發明，在C r含有量低於1 0 % 以下之情況下，並無連續地形成Cr2〇3層，因此，由外部開始之氧進入係變得顯著，形成圖4所示之所謂内部氧化層3。内部氧化層3係藉由C r或S i之所謂和氧之親和力大之元素優先地進行氧化而發生，在觀察鋼板之剖面組織時，能夠以所謂在鋼板結晶粒界之優先氧化6或者是在粒内之氧化物形成7之形式而進行確認。在本發明，藉由脫銹皮處理而除去形成於銹皮/鋼板界面2内側之内部氧化層3以及包含附隨於這個所形成之脫鉻層4之部分係變得重要，藉此而非常地提高塗裝後之财钱性。本發明者們係還由所謂塗裝密合性之觀點而也全心地進行檢討。結果，發現到：在熱軋後，在藉由酸洗而進行脫銹皮之鋼板，於顯著地發生粒界侵蝕時，黏性大之塗料潤濕性原因，塗料無法充分地流入至粒界侵14部，因此，鋼板和塗料間之密合性係降低。在存在前述脫鉻層之部分，特別容易引起在粒界之鉻量降低，因此，容易發生粒界侵蝕。在塗裝密合性降低時，容易在塗膜和鋼板間，形成間隙構造，使得塗裝後之耐蝕性降低。根據這些意見而檢討同時達成塗裝密合性和塗裝後之耐蝕性雙方之條件。表1及圖1係使用藉由實機所製造之9 % Cr鋼熱軋板，在實驗室，進行藉由喷砂及硫酸、氟酸一硝酸酸洗所造成之脫銹皮，評價在改變鋼板表面除去量之情況下之鋼板财钱性和塗裝後财姓性之結果之一例子。由該結果而得知：正如本發明，除了藉由在含有6 . 0〜1 0. 0 20 312/發明說明書(補件)/92-11/92124190 200404904 % Cr之鋼，於脫銹皮步驟，除去鋼板表面10//m以上而提高鋼板之耐蝕性以外，還改善塗裝密合性，提高塗裝後之耐蝕性。此外，使得（鋼板内部之C r濃度）一（鋼板表面之 C r濃度）之C r濃度差成為1 %以下，係不僅改善鋼板本身之表面耐餘性，並且，正如以下所示，也具有透過減少由於粒界侵蝕所造成之凹凸而提高塗裝後之耐蝕性能之效果，在鋼板除去量成為10//m以上，（鋼板内部之Cr濃度） _(鋼板表面之C r濃度）之C r濃度差係成為1 %以下，在該情況下，塗裝後之耐蝕性係變得良好。在此，所謂鋼板内部之C r濃度係並無脫C r層之影響之鋼板之板厚中央部附近之Cr濃度，在熱軋板或熱軋退火板之情況下，係指由鋼板表面開始超過2 0 0 # m之内部部分之C r濃度。在冷軋退火板之情況下，係指對於板厚t之t / 4以上内部之部分之Cr濃度。在鋼板内部之Cr濃度係可以藉由使用ΕΡΜΑ 或E D X、螢光X射線等之分析法、固體發光分光分析法，或者是在呈化學地進行溶解後，藉由進行利用高頻感應偶合電漿發光分析法（Inductively Coupled Plasma -Atomic E m i s s i ο n (感應偶合電漿一原子發射）、以下稱為I C P法）或滴定法所達成之定量等之方法而進行測定。在藉由E P M A 分析等而進行局部之C r濃度測定之情況下，必須選擇並無存在於板厚中心部之偏析部影響之測定部位。圖2係對於鋼板表面除去量8//m及40//m之情況下之鋼板表面來進行掃描式電子顯微鏡觀察之結果。在表面除去量8 # m之例子，得知：結晶粒界優先深度地進行侵钱。另 21 312/發明說明書(補件)/92-11/92124190 200404904 一方面，在除去鋼板表面4 0 // m之情況下，並無確認到顯著之粒界侵I虫。圖3係藉由輝光放電分光分析（G D S)而測定由鋼板表面開始至板厚方向之F e和C r濃度側面圖之結果。在鋼板表面除去量8/zm之鋼板，於鋼板之表面附近，殘留脫鉻層，相對地，在鋼板表面除去量成為40/zm之情況下，並無觀察到脫鉻層。在就這些鋼板使用電子線微分析儀（Ε Ρ Μ A)而測定C r濃度時，在8 μ m除去材，使得鋼板表面之C r濃度比起鋼板内部之Cr濃度（在除去鋼板表面500/ζιη後而藉由 ICP法之所定量之值：9mass(質量）％ )還更加降低2·5 mass(質量）％，相對地，在40#m除去材，使得鋼板表面之C r濃度幾乎一致於鋼板内部之C r濃度。此外，就鋼板表面之白色度而進行根據J I S Z 8 7 1 5之測定，結果，8 // m 除去材之白色度指數係大約6 2，相對地，在4 0 # m除去材，成為6 8。就各種熱軋鋼板而調查白色度，結果，很明顯地得知：在白色度指數大概成為6 5以上時，並無顯著之粒界侵餘，也改善鋼板之塗裝财#性。此外，在白色度之測定，使用美利達相機公司製、C Μ — 1 0 0 0型分光測色計。像這樣，認為在鋼板表面之除去量未滿1 0 # m時，無法完全地除去内部氧化層3或脫鉻層4，無法得到充分之耐蝕性，並且，粒界侵蝕變大，塗裝密合性降低，塗裝後之而才餘性也降低。此外，在超過2 0 0 // m而除去鋼板表面時，會有所謂由於脫銹皮所造成之損失變大、成本上升並且生成於酸洗槽中之所謂污垢（s m u t)附著於鋼板表面而損害耐 22 312/發明說明書(補件)/92-11/92124190 200404904 蝕性或者是損害鋼板外觀之問題發生之情況產生。更加理想之鋼板表面除去量係15//II1以上、更加希望是20//m以上。以前面所示之詳細檢討作為基礎而藉由隨著Cr鋼之鋼板表面除去之所造成之鋼板表面性狀之控制以及内部氧化層3或脫鉻層4之除去而造成之塗裝後之耐蝕性提升係本發明之重要之要點；藉由同樣之詳細檢討而發現到：藉由除去鋼板表面10#m以上、更加理想是15//m以上、更加希望是20//m以上，並且，使得該鋼板表面之Cr濃度成為 (鋼板内部之Cr濃度一 lmass(質量）％ )以上而顯著地改善塗裝耐姓性。此外，在表1之鋼板耐蝕性係根據J I S Z 2 3 7 1，藉由進行4小時之鹽水喷霧試驗後之銹面積率而進行評價，使得銹面積率成為2 0 %以下者，成為良好。此外，塗裝後之耐蝕性係就在表面施加目標乾燥膜厚5 0 # m之丙烯酸樹脂塗裝而由上面施以橫切之樣本，根據根據J I S Z 2 3 7 1而進行 1 0 0 0小時之鹽水喷霧試驗，使得在樣本下部不產生銹積存之顯著流動銹之情況，成為良好。此外，具體地說，鋼板表面除去量之測定係測定藉由噴砂而呈機械式地除去銹皮後之重量和尺寸以及進行酸洗後之重量，將這些重量差除以樣本之表面積，在計算鋼板之除去量（g/ m2)後，使用鋼板密度（7.8g/cin3)而求出鋼板之除去厚度（// m)。在本發明之熱軋板之脫銹皮法係並無特別限定。可以使用一般已經知道之喷砂或刷子、或者是利用小直徑滾筒等 23 312/發明說明書(補件)/92-11/92124190 200404904 之機械除去方法、利用鹽酸、硫酸、硝酸、氟酸、硝酸氟酸或氯化鐵等之化學除去方法等之習知方法。 (1 7 )脫銹皮後之步驟可以使得該脫銹皮後之鋼板，成為本發明鋼。此外，對於前述脫銹皮後之鋼板來冷軋至既定板厚為止後，也以使得退火、酸洗後之鋼板，成為本發明鋼。在冷軋退板，表面係十分地平滑，因此，認為並無隨著前述塗裝合性不良而造成之耐蝕性降低，但是，在熱軋板之脫銹變得不充分時，也在冷軋退火後，無法得到充分之耐蝕必在藉由熱軋板之脫銹皮處理而完全地除去銹皮正下方之部氧化層3和脫鉻層4之本發明鋼，即使是在冷軋退火之鋼板，也可以得到充分之耐蝕性。在冷軋之壓下量係好是成為3 0 %以上。冷軋後之鋼板係最好是以軟質化之的而進行退火，此時之退火條件係最好是成為6 0 0 °C以上。冷軋退火後之鋼板係可以在進行酸洗或者是根據這之處理後，進行JISG4305所規定之各種表面精加工。考量塗裝後之耐蝕性之情況下，最好是成為N 〇. 2 B之精 (1 8 )塗裝方法塗裝係藉由吹附塗敷、毛刷塗敷等而進行，在塗料，以使用以丙烯酸樹脂塗料、苯二酸樹脂塗料、環氧樹脂料、聚胺基曱酸乙酯樹脂塗料等為首之J I S K 5 5 0 0所記之各種塗料。可以在塗裝前，塗裝初期銹防止用之各種漆。可以配合需要而施加各種使用防銹塗料或樹脂塗料 312/發明說明書(補件)/92-11/92124190 + 在可火密皮 :〇内後最因個在加可塗載底之 24 200404904 底漆塗裝或者是中間塗層塗裝。此外，本發明鋼係具有鋼材本身更高於普通鋼之财钱性，並且，也具有良好之鋼板表面和上面塗層塗料間之密合性，因此，也可以省略底漆塗裝或下層塗層、中間塗層塗裝，也能夠將黏度高之上層塗層塗裝，直接地塗裝在鋼板上。在考慮作為冷凍貨櫃之使用之情況下，為了得到充分之耐蝕性，因此，必須使得塗膜厚度，成為1 0 # m以上。在使用作為住宅構造材之情況或特別是不需要高耐蝕性之構件等，可以隨著所使用之用途而不施加塗裝。 (1 9 )本發明鋼之機械性質之目標在使用作為構造用鋼材時，成為韌性指標之蕭氏撞擊值之值係必須成為在- 25°C之50 J / cm2以上。特別是在考慮作為冷凍貨櫃材之使用或者是在寒冷地住宅用途之使用之情況下，最好在_25°C下為80J/cm2以上。希望在抗拉試驗之延伸值越大越好，但是，為了能夠進行對於各種形狀之加工，因此，必須成為3 0 % 以上。此外，降伏比係成為加工難易或使用在住宅之情況下之耐震性能之指標之值，希望越低越好，但是，作為構造材係必須成為8 0 %以下，更加理想之範圍係75%以下。 (2 0 )本發明鋼之塗裝後之耐蝕性之目標冷凍貨櫃用鋼材係幾乎在所有情況下，由於耐蝕性之提升或者特別是創意性之觀點而在表面施加各種塗裝。因此，塗裝後之耐蝕性係變得重要。本發明者們係進行實際所使用之鋼材塗裝後之耐蝕性和藉由鹽水喷霧所造成之促 25 312/發明說明書(補件)/92-11/92124190 200404904 進試驗結果之詳細之比較檢討，結果，得到：所謂在後施以橫切之試驗片之鹽水喷霧試驗而在1 0 0 0小時巧生顯著之流動銹之情況下，即使是在實際之使用，也充分耐蝕性之結論。以該基準作為根本，進行塗裝後餘性評價。 (實施例）藉由真空熔解而使得鋼原料熔製、造塊成為表2所化學組成，製造5 0 k g鋼塊，加熱至1 2 0 0 °C，保持1 後，進行熱軋而成為4mm厚度之熱軋板。在這些熱軋半數，進行6 5 0 °C X 1 0小時之均勻化退火（熱軋板退火在仍然成為熱軋之鋼板和熱軋板退火之鋼板，施加藉砂以及接著這個之氟酸一硝酸之混合酸酸洗所造成之皮，成為除去鋼板表面大約1 5 // m之熱軋鋼板。此外板表面之除去量係藉由喷砂而測定呈機械式地除去銹之重量和尺寸、以及進行酸洗後之重量，以這些重量除以樣本之表面積，在計算鋼板之除去量（g/cm2)後用鋼板之密度（7.8g/cm3)而求出鋼板之除去厚度此外，藉由在酸洗，使用溫度成為4 0〜6 0 °C之1〜2 m a ϊ 量）％氟酸一1 3〜1 5 m a s s (質量）％硝酸溶液，重複地進 3 0秒鐘之取出而測定洗淨後之重量，以便於成為所要鋼板表面除去量。就No. 1鋼而言，改變鋼板表面除去量之樣本係也2 作為比較用。就這些而言，藉由對於鋼板表面來進行分析而求出鋼板表面之Cr濃度。在ΕΡΜΑ之加速電壓 312/發明說明書(補件)/92-11/92124190 塗裝 :產具有之耐示之小時板之 •)。由喷脫銹，鋼皮後差來，使 η ) 〇丨s (質行每求之 L備 ΕΡΜΑ 係成 26 200404904 為1 5 k V。認為在該條件下之資訊係大概反映鋼板表面〜 0.5//m深度之範圍濃度。就No.l鋼之鋼板内部之Cr濃度而言，在除去鋼板表面500//m後，進行藉由ICP法所造成之定量分析，結果，成為9.1mass(質量）％。鋼板表面除去量成為5//m和8//m之情況下之鋼板表面之Cr濃度係分別成為5.1mass(質量）％、6.6mass(質量）％，但是，鋼板表面除去量成為15/zm之情況下之鋼板表面之Cr濃度係 8.3mass(質量）％，成為（鋼板内部之Cr濃度-1)%以上。就其他鋼板而言，將進行同樣之C r濃度測定之結果，顯示在表3。鋼板表面除去量成為15/zm之情況下之鋼板表面之C r濃度係皆成為（鋼板内部之C r濃度-1 ) %以上。由這些熱軋鋼板製品，切出板厚x 50x 100(mm)板，在表面，藉由吹附塗裝而施加利用目標乾燥膜厚5 0 # m之丙烯酸矽酮樹脂系塗料（關西油漆公司製、SILIC0TECTC西里可得庫通）AC上層塗料、SILICOTECT AC TOP COAT)所造成之塗裝，就由上面開始而呈X狀地施以橫切之樣本而言，按照J I S Z 2 3 7 1而進行1 0 0 0小時之鹽水喷霧試驗（5 % N a C卜 3 5 °C、p Η 6 . 5〜7 . 2 )，測定一直到在樣本下部產生銹積存之顯著之流動銹為止之時間。此外，塗料之乾燥膜厚係藉由使用磁性法之電磁式膜厚計及顯微鏡法而確認塗膜之剖面。乾燥膜厚係大約5 0 // m。此外，採取藉由研削鋼板之兩表面0.75mm而成為板厚2. 5mm並且沿著報軋方向而在直角造成2mmV凹口之根據JIS Z 2 2 0 2之副尺寸之蕭氏撞擊試驗片，根據J I S Z 2 2 4 2而測定-2 5 °C之蕭氏撞擊值（J / 27 312/發明說明書(補件)/92-11/92124190 200404904 c m2)。將該結果，顯示在表3。在2 m m t以下之冷蕭氏撞擊值係在通常之方法，無法進行測定，但在鋼板之板厚變薄時，韌性值係變大（例如參照熔 VoK 6 1 ( 1 9 9 2 )、No. 8、ρ· 6 3 6 )，此外，在組織上板係比起熱軋鋼板，還更加有利於蕭氏撞擊值，軋鋼板之-2 5 °C之蕭氏撞擊值係相同於在熱軋鋼相者是這個以上。因此，如果板厚變厚之熱軋鋼板擊值顯示充分值的話，則以這個作為素材所製造薄之冷軋鋼板之蕭氏撞擊值係也成為充分值。在使用No.2鋼之並無施加熱軋板退火之鋼，作成0 之冷軋、退火板，作成仍然0 . 7 m m厚度之2 m m V凹試驗片，使用小型（lOkgf = 98N)之蕭氏試驗機， °C之吸收能量，結果，得到所謂1 5 0 J / c m2之良此外，在分別對於前述熱軋、酸洗鋼板來冷軋成厚度後，接著於7 5 0 °C X 1分鐘之退火後，施加藉電解一硝酸電解所完成之脫銹皮，成為冷軋鋼板性鹽電解條件係成為在使得液溫成為7 0〜8 0 °C之 N a 2 S 0 4溶液中而電量1 0 0〜2 0 0 C / d m2之條件。此電解條件係成為在使得液溫成為5 0〜6 0 °C之1 0 % 液中而電量2 0〜4 0 C / d m2之條件。由這些冷軋鋼板製品而沿著輥軋方向，來採取號抗拉試驗片，按照J I S Z 2 2 4 1而進行抗拉試驗伸和降伏比。此外，切出板厚X 5 0 X 1 0 0 ( m m )板，藉由吹附塗裝而施加目標乾燥膜厚5 0 // m之丙婦 312/發明說明書(補件)/92-11/92124190 軋鋼板之是，一般接學會誌，冷軋鋼因此，冷 ί之值或之蕭氏撞之板厚變實際上， .7mm厚度口之蕭氏測定- 2 5 .好結果。，為 0.7mm 由中性鹽製品。中 2 0¾ 外，硝酸 HN〇3 溶 JIS13B ，測定延在表面，酸矽酮樹 28 200404904 脂系塗料（關西油漆公司製、SILICOTECT AC上層塗料、 SILICOTECT AC TOP COAT)所完成之塗裝，就由其上面開始而呈X狀地造成橫切之樣本而言，按照J I S Z 2 3 7 1而進行 1 0 0 0小時之鹽水喷霧試驗（5 % N a C 1、3 5 °C、p Η 6 · 5〜7 · 2 )，測定一直到在樣本下部產生銹積存之顯著之流動銹為止之時間。此外，塗料之乾燥膜厚係藉由使用磁性法之電磁式膜厚計及顯微鏡法而確認塗膜之剖面。大約成為5 0 // m。將這些測定結果，顯示在表3。由表3而得知：成為本發明例之鋼1〜1 0及鋼1 8〜1 9 係不論有無熱軋板之退火，韌性（蕭氏撞擊值）成為5 0 J / cm2，並且，延伸成為33%以上，而且，降伏比成為75% 以下。此外，顯示在1 0 0 0小時之鹽水喷霧試驗而不產生流動銹之良好耐蝕性。另一方面，鋼組成成為本發明範圍外之比較例之鋼1 1〜1 7係不論有無熱軋板之退火，勃性、延伸、降伏比、耐蝕性中之至少一個係皆無法達到良好之水準。此外，就某些成分鋼而言，確認：進行使用大量生產設備之實機製造而得到本發明之效果。 29 312/發明說明書(補件)/92-11/92124190 200404904 表1 鋼板表面除去量（# m) 鋼板耐蝕性塗裝後之耐蝕性鋼板内部之Cr濃度 —鋼板表面之Cr濃度（mass% ) 5 不良不良 4. 0 8 不良不良 2.5 10 良好良好 1 . 0 14 良好良好 0. 8 20 良好良好 0. 4 40 良好良好 0. 0 80 良好良好 0. 0 110 良好良好 0. 0 312/發明說明書(補件)/92-11/92124190 200404904 ιε i f#s^4 5Φ4 f4s^4 f4ff^4 ¥ 4 5^^4 f#s^4 5^^-4 f在銻qq 90 ·0Is a steel key (slab). Then, the steel spiral is heated to be a hot-rolled steel sheet through a hot rolling step. In addition, the steel ingot after casting may be placed in a heating furnace before being cooled to room temperature, or the steel key after casting may be directly hot-rolled. The reheating temperature of the hot-rolled steel key in the case of reheating the ingot is not particularly limited. However, in order to omit the annealing step of the hot-rolled sheet, the coiling temperature must be increased. As a result, the reheating temperature of the ingot The system should preferably be above 1050 ° C. On the other hand, when the reheating temperature exceeds 1250 ° C, not only the loss due to the oxidation of the surface of the steel bond during heating increases, but also the problem of sagging of the ingot may occur. In addition, due to the composition of the steel, a part of the steel is transformed into a 5-ferrous iron phase, which may impair the workability in the hot room. The rolling reduction conditions and temperature conditions for hot rolling are not particularly limited. However, it is preferable to perform rolling at least once with a rolling reduction of 30% or more. By rolling under the strong pressure, the crystal grains of the steel sheet are refined to improve the low-temperature tensile properties of the base material. From the standpoint of the promotion of softening after coiling by the reel, it is desirable that the finishing temperature of the hot rolling becomes 900 ° C or higher, preferably more than 930 ° C. It is possible to prevent the introduction of processed ferrous iron due to rolling in the 2-phase region of a + r by making the finishing temperature in hot rolling more than 900 ° C, and to ensure high coiling The temperature, therefore, can suppress the formation of hard hemp iron phases during cooling after coiling. From the standpoint of softening after coiling, it is desirable that the coiling temperature at hot rolling is 80 ° C or higher, and preferably 8100 ° C or higher. After the completion of hot rolling, if the strength adjustment is required, etc., the annealing of the hot rolled sheet can be applied according to the needs. In the case of hot-rolled sheet annealing, the temperature can be batch annealing or continuous annealing above 60 ° C 18 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904. In the case of batch annealing, the annealing time is preferably 1 hour or more. Then, the scale and the surface of the steel plate are removed by sand blasting or pickling. It is possible to apply the reduction achieved by quenching and tempering on the steel sheet after hot rolling, hot rolling annealing or descaling for the purpose of shape correction. (16) Removal amount on the surface of the steel sheet in the descaling step The amount of removal in the descaling step is an important matter of the property after coating which is the focus of the present invention. Here, the so-called removal amount 1 of the surface of the steel sheet of the present invention is as shown in the schematic diagram of FIG. 4, and becomes the thickness in the thickness direction starting from the so-called scale / steel interface 2 and includes the thickness of the internal oxide layer 3 and the dechromized layer 4. . On the surface of the steel sheet after hot rolling or hot rolling annealing, a skin layer 5 mainly composed of oxides of Fe and Cr is formed. In the outer layer, a spinel structure phase mainly composed of Fe is formed, and an inner layer is formed. , Forming a spinel phase with Fe and Cr as the main body. It has been known that when a steel sheet such as a hot-rolled coil is exposed to high temperatures for a long time, Cr is preferentially oxidized as the scale layer 5 near the steel sheet grows, because it is too late to perform a Cr diffusion from the steel sheet Due to the supply, a dechromized layer 4 is formed on the steel plate side directly below the scale. When the dechromized layer 4 remains on the surface of the steel sheet after descaling, the corrosion resistance is significantly reduced. Therefore, it is important to completely remove the dechromized layer 4 on the surface of the steel sheet in the descaling step. In a so-called stainless steel containing 11% or more of Cr, a dense layer mainly composed of Cr203 is formed continuously on the inner side of the spinel layer. Therefore, the entry of oxygen toward the steel plate from the outside is suppressed. Therefore, the thickness of the dechromizing layer 4 is less than 10 19 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904 // m from the scale / steel interface. However, as in the present invention, when the Cr content is less than 10%, the Cr203 layer is not continuously formed. Therefore, the oxygen entry system from the outside becomes significant, forming the structure shown in FIG. 4 So-called internal oxide layer 3. The internal oxide layer 3 is preferentially oxidized by the so-called Cr or Si element that has a large affinity with oxygen. When observing the cross-section structure of a steel sheet, it can be preferentially oxidized at the grain boundary of the steel sheet 6 or It was confirmed that the intra-granular oxide formed 7 form. In the present invention, it is important to remove the internal oxide layer 3 formed on the inner side of the scale / steel plate interface 2 and the portion including the formed dechromizing layer 4 by the descaling process. To improve the money after painting. The present inventors also conducted a thorough review from the viewpoint of so-called paint adhesion. As a result, it was found that, after hot-rolling, when a steel sheet subjected to descaling by pickling was significantly eroded at the grain boundary, the wettability of the paint with large viscosity caused the coating to fail to sufficiently flow into the grain boundary Invading 14 parts, the adhesion between the steel sheet and the paint was reduced. In the portion where the dechromizing layer is present, the amount of chromium at the grain boundary is particularly liable to decrease, and therefore, grain boundary erosion is liable to occur. When the coating adhesion is reduced, it is easy to form a gap structure between the coating film and the steel sheet, which reduces the corrosion resistance after coating. Based on these comments, review the conditions for achieving both paint adhesion and corrosion resistance after painting. Table 1 and Figure 1 are based on 9% Cr steel hot-rolled steel plate manufactured by the actual machine. In the laboratory, descaling caused by sand blasting and sulfuric acid and fluoric acid-nitric acid pickling was performed. The evaluation is changing. An example of the results of the property of the steel plate and the property of the property after painting when the surface of the steel plate is removed. From this result, it is known that, as in the present invention, in addition to the rust-removing step in the steel containing 6.0 to 1.00 20 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904% Cr, In addition to improving the corrosion resistance of the steel sheet by 10 // m or more on the surface of the steel sheet, it also improves the coating adhesion and the corrosion resistance after coating. In addition, making the difference in C r concentration between (C r concentration inside the steel plate) and (C r concentration on the steel plate surface) less than 1% not only improves the surface resistance of the steel plate itself, but also, as shown below, also has By reducing the unevenness caused by grain boundary erosion and improving the corrosion resistance after painting, the removal amount of the steel plate becomes 10 // m or more, (Cr concentration inside the steel plate) _ (C r concentration on the surface of the steel plate) C The r concentration difference is 1% or less, and in this case, the corrosion resistance after coating becomes good. Here, the so-called C r concentration inside the steel sheet refers to the Cr concentration near the central part of the thickness of the steel sheet without the influence of the de-Cr layer. In the case of a hot-rolled sheet or a hot-rolled annealed sheet, it refers to the surface of the steel sheet. C r concentration in the internal part exceeding 2 0 0 # m. In the case of a cold-rolled annealed sheet, it refers to the Cr concentration for the inner part of t / 4 or more of the sheet thickness t. The Cr concentration in the steel plate can be analyzed by using EPMA, EDX, fluorescent X-rays, solid-state spectroscopy, or after chemically dissolving, by using a high-frequency induction coupling plasma. Luminescence analysis (Inductively Coupled Plasma-Atomic E missi οn (inductively coupled plasma-atomic emission), hereinafter referred to as the ICP method) or titration method to achieve the quantitative measurement. In the case where the local C r concentration measurement is performed by an EPMA analysis or the like, it is necessary to select a measurement site which is not affected by the segregation portion existing in the center portion of the plate thickness. Fig. 2 shows the results of the scanning electron microscope observation on the surface of the steel sheet in the case of the steel sheet surface removal amounts of 8 // m and 40 // m. In the example of the surface removal amount of 8 # m, it was found that the grain boundary preferentially penetrates the money in depth. In addition, 21 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904 On the one hand, when the surface of the steel plate was removed by 4 0 // m, no significant grain boundary invasion was confirmed. Fig. 3 is a result of a side view of the F e and C r concentrations measured from the surface of the steel plate to the thickness direction by a glow discharge spectroscopic analysis (G DS). On the steel sheet surface with a removal amount of 8 / zm, a dechromized layer remained near the surface of the steel sheet. On the other hand, when the steel sheet surface removal amount was 40 / zm, no dechromized layer was observed. When the C r concentration was measured using an electron beam microanalyzer (EP M A) on these steel plates, the material was removed at 8 μm so that the C r concentration on the surface of the steel plate was higher than the Cr concentration inside the steel plate (500 / ζιη and the value quantified by the ICP method: 9mass (mass)%, and further reduced by 2.5 mass (mass)%. In contrast, the material was removed at 40 # m, so that the C r concentration on the surface of the steel plate was almost Consistent with the C r concentration inside the steel plate. In addition, the whiteness of the surface of the steel sheet was measured according to JISZ 8 7 1 5. As a result, the whiteness index of the 8 // m removed material was about 6 2. In contrast, the removed material at 4 0 # m was 6 8 . As a result of investigating the whiteness of various hot-rolled steel sheets, it became clear that when the whiteness index was about 65 or more, there was no significant grain boundary leeway and the coating properties of the steel sheets were improved. In addition, for measurement of whiteness, a CM-1000 spectrophotometer manufactured by Merida Camera Co., Ltd. was used. In this way, it is considered that when the removal amount on the surface of the steel sheet is less than 10 # m, the internal oxide layer 3 or the dechromized layer 4 cannot be completely removed, sufficient corrosion resistance cannot be obtained, and the grain boundary erosion becomes large and the coating is dense The compatibility is reduced, and the margin after coating is also reduced. In addition, when the surface of the steel sheet is removed in excess of 2 0 // m, there are so-called smuts caused by the loss caused by descaling, which increases the cost, and is generated in the pickling tank. Damage resistance 22 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904 Corrosion or the problem of damage to the appearance of the steel plate occurs. A more desirable steel plate surface removal amount is 15 // II1 or more, and more preferably 20 // m or more. Based on the detailed review shown above, the corrosion resistance after coating caused by the control of the surface properties of the steel sheet caused by the removal of the surface of the Cr steel sheet and the removal of the internal oxide layer 3 or dechromized layer 4 Lifting is an important point of the present invention; it was found through the same detailed review: by removing the surface of the steel plate from 10 # m or more, more preferably 15 // m or more, and more preferably 20 // m or more, and The Cr concentration on the surface of the steel sheet becomes (Cr concentration inside the steel sheet-lmass (mass)%) or more, and the survivability of the coating is significantly improved. In addition, the corrosion resistance of the steel sheet in Table 1 was evaluated based on the rust area ratio after a salt water spray test for 4 hours based on J I S Z 2 3 7.1, and the rust area ratio of 20% or less was good. In addition, the corrosion resistance after coating is applied on the surface with an acrylic resin coating with a target dry film thickness of 50 # m, and a cross-cut sample is applied from the top, according to JISZ 2 3 7 1 for 100 hours. The salt water spray test made the situation that no significant rust accumulation occurred in the lower part of the sample, which was good. In addition, specifically, the measurement of the amount of steel sheet surface removal is to measure the weight and size after mechanically removing the scale by sandblasting, and the weight after pickling, and divide these weight differences by the surface area of the sample. After the steel plate removal amount (g / m2), the steel plate density (7.8 g / cin3) was used to determine the steel plate removal thickness (// m). The descaling method in the hot-rolled sheet of the present invention is not particularly limited. You can use sandblasting or brushes that are generally known, or use a small diameter roller, etc. Conventional methods such as chemical removal methods such as fluoric acid and ferric chloride. (17) Steps after descaling The steel sheet after descaling can be made into the steel of the present invention. In addition, after the steel sheet after the descaling is cold-rolled to a predetermined thickness, the steel sheet after annealing and pickling also becomes the steel of the present invention. The surface of the cold-rolled sheet is very smooth. Therefore, it is considered that the corrosion resistance does not decrease due to the poor coating adhesion. However, when the derusting of the hot-rolled sheet becomes insufficient, it is also cold. After rolling and annealing, sufficient corrosion resistance cannot be obtained. The steel of the present invention, in which the oxide layer 3 and the dechromized layer 4 directly under the scale are completely removed by the descaling treatment of the hot-rolled sheet, even in cold rolling annealing The steel plate can also obtain sufficient corrosion resistance. The reduction in cold rolling is preferably 30% or more. The steel sheet after cold rolling is preferably annealed by softening, and the annealing conditions at this time are preferably 60 ° C or higher. After cold rolling and annealing, the steel sheet can be subjected to various surface finishes specified in JIS G4305 after being pickled or treated in accordance with this. In the case of considering the corrosion resistance after painting, it is preferable to be a fine coating of No. 0.2 B (1 8). The painting method is performed by blow coating, brush coating, etc. Various coatings described in JISK 5500 including acrylic resin coatings, phthalic acid resin coatings, epoxy resin materials, and polyurethane resin coatings are used. Various paints can be used to prevent rust before painting. Can be applied in accordance with the needs of various anti-rust coatings or resin coatings 312 / Invention Manual (Supplements) / 92-11 / 92124190 + Within the heat-tight skin: 〇 The most important reason is to add the paintable base 24 200404904 bottom Lacquer or intermediate coating. In addition, the steel of the present invention has a higher cost of steel itself than ordinary steel, and also has good adhesion between the surface of the steel plate and the coating on the upper surface. Therefore, the primer coating or the lower coating can also be omitted. It is also possible to coat the upper layer and intermediate coating, and directly coat the high-viscosity coating on the steel plate. When considering the use as a refrigerated container, in order to obtain sufficient corrosion resistance, the thickness of the coating film must be made 10 # m or more. In the case of using it as a housing construction material, or in particular, a member that does not require high corrosion resistance, etc., it is not necessary to apply a coating depending on the application used. (19) Objective of mechanical properties of the steel of the present invention When a steel material for construction is used, the value of the Xiao impact value, which is an index of toughness, must be 50 J / cm2 or higher at -25 ° C. Especially when considering the use as a refrigerated container material or the use in cold residential buildings, it is better to be 80J / cm2 or more at _25 ° C. The larger the elongation value in the tensile test, the better. However, in order to be able to process various shapes, it must be 30% or more. In addition, the reduction ratio is a value that is an index of seismic resistance in the case of difficulty in processing or in the case of residential use. The lower the number, the better. However, it must be 80% or less as a structural material system, and a more desirable range is 75% or less. . (20) Target of corrosion resistance after coating of the steel of the present invention The steel for refrigerator containers is subjected to various coatings on the surface in almost all cases due to the improvement of the corrosion resistance or the viewpoint of creativity. Therefore, the corrosion resistance after painting becomes important. The inventors made a detailed comparison of the corrosion resistance of the actual steel used after painting and the acceleration caused by salt water spray 25 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904 As a result of the review, it was obtained that the so-called brine spray test of a cross-cut test piece was performed at the time of 1000 hours to produce significant flowing rust. Even in actual use, it has sufficient corrosion resistance. in conclusion. Based on this standard, the residual performance evaluation after painting was performed. (Example) The steel material was melted and formed into a chemical composition as shown in Table 2 by vacuum melting. A 50 kg steel block was manufactured, heated to 12 0 ° C, maintained at 1, and then hot rolled to 4 mm. Thickness of hot rolled sheet. In these hot-rolled half, a homogenizing annealing at 650 ° CX for 10 hours is performed (hot-rolled sheet annealing is performed on the still-hot-rolled steel sheet and the hot-rolled sheet-annealed steel sheet, and sand fluoric acid and nitric acid are added after this. The skin caused by the mixed acid pickling is a hot-rolled steel sheet with a surface removed of about 15 // m. In addition, the amount of surface removal is determined by sand blasting to measure the weight and size of mechanically removed rust, and After pickling the weight, divide these weights by the surface area of the sample, calculate the steel plate removal amount (g / cm2), and then use the density of the steel plate (7.8g / cm3) to determine the thickness of the steel plate. Pickling, the use temperature is 1 ~ 2 ma at 40 ~ 60 ° C (amount)% fluoric acid-1 3 ~ 1 5 mass (mass)% nitric acid solution, repeatedly take out for 30 seconds to measure and wash The net weight is to make it the desired amount of steel surface removal. In the case of No. 1 steel, Sample No. 2 in which the amount of steel plate surface removal was changed was also used for comparison. In these cases, the Cr concentration on the surface of the steel sheet was obtained by analyzing the surface of the steel sheet. Accelerated voltage at EPMA 312 / Invention Specification (Supplement) / 92-11 / 92124190 Painting: Produced withstandable hours as shown on the board •). After spraying off the rust, the steel sheet is worse, so that η) 〇s (the quality of each prepared LEPEPMA system is 26 200404904 is 15 kV. It is believed that the information system under this condition reflects the steel plate surface ~ 0.5 The concentration in the range of // m depth. Regarding the Cr concentration inside the steel plate of No.l steel, after removing the surface of the steel plate by 500 // m, a quantitative analysis by ICP method was performed. )%. The Cr concentration on the surface of the steel sheet when the steel sheet surface removal amount is 5 // m and 8 // m are 5.1 mass% and 6.6 mass% respectively, but the steel sheet surface removal amount becomes The Cr concentration on the surface of the steel sheet at 15 / zm is 8.3 mass (mass)%, and becomes (Cr concentration inside the steel sheet -1)% or more. For other steel sheets, the same C r concentration measurement results will be performed. The results are shown in Table 3. The C r concentration on the surface of the steel sheet when the removal amount of the steel sheet surface was 15 / zm was all (Cr concentration in the steel sheet -1)% or more. From these hot-rolled steel sheet products, the sheet thickness was cut out. x 50x 100 (mm) board, apply the target by spray coating on the surface The acrylic silicone resin coating with a dry film thickness of 5 0 # m (made by Kansai Paint Co., Ltd., SILIC0TECTC Silicone Kutong) AC top coating, SILICOTECT AC TOP COAT), the X-shaped coating from the top For cross-cut samples, a salt water spray test was performed for 10,000 hours in accordance with JISZ 2 3 71 (5% Na C 3 35 ° C, p Η 6. 5 ~ 7.2) Measure the time until significant flowing rust accumulates in the lower part of the sample. In addition, the dry film thickness of the coating material was confirmed by using an electromagnetic film thickness meter using a magnetic method and a microscope method to confirm the cross-section of the coating film. The dry film thickness is about 5 0 // m. In addition, a Xiao's impact test piece according to JIS Z 2 2 0 2 with a secondary thickness of 2.5 mm and a plate thickness of 2.5 mm by grinding 0.75 mm on both surfaces of the steel plate along the rolling direction, The Xiao impact value at -2 ° C (J / 27 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904 c m2) was measured in accordance with JISZ 2 2 4 2. The results are shown in Table 3. Cold Shock impact values below 2 mmt are common methods and cannot be measured, but when the plate thickness of the steel sheet becomes thinner, the toughness value becomes larger (for example, see VoK 6 1 (1 9 9 2), No 8, ρ · 6 3 6). In addition, the plate on the structure is more conducive to the Shock impact value than the hot-rolled steel plate. The steel rolling phase is more than this. Therefore, if the hit value of a hot-rolled steel sheet with a thicker plate thickness becomes a sufficient value, the Xiao impact value of a thin cold-rolled steel sheet manufactured with this material becomes a sufficient value. For steels using No. 2 steel without hot-rolled sheet annealing, 0 cold-rolled and annealed sheets were made, and 2 mm V-concave test pieces with a thickness of 0.7 mm were made. A small (10 kgf = 98 N) Xiao was used. The tester absorbs energy at ° C. As a result, the so-called goodness of 150 J / cm2 is obtained. In addition, after cold rolling the thickness of the hot-rolled and pickled steel sheet, respectively, it is then heated at 7 50 ° CX 1 After annealing for one minute, descaling completed by electrolytic-nitric acid electrolysis is applied, and the conditions for cold-rolled steel sheet salt electrolysis are applied in a Na 2 S 0 4 solution at a liquid temperature of 70 to 80 ° C. The condition of electric quantity 1 0 ~ 2 0 0 C / d m2. This electrolytic condition is a condition in which the liquid temperature is 10% of the liquid at 50 to 60 ° C and the electric quantity is 20 to 4 C / d m2. From these cold-rolled steel sheet products, a tensile test piece No. was taken along the rolling direction, and the tensile test was performed in accordance with J I S Z 2 2 4 1 elongation and reduction ratio. In addition, a plate with a thickness of X 5 0 X 1 0 0 (mm) was cut out, and a target dry film thickness of 5 0 // m was applied by blow-coating. 312 / Invention Manual (Supplement) / 92-11 / 92124190 Rolled steel sheet is generally used as a guide for cold rolled steel. Therefore, the value of cold or Xiao's plate thickness becomes practical, and the Xiao's measurement of .7mm thickness mouth-2 5. Good results. , 0.7mm from neutral salt products. In addition to middle ¾, nitric acid HN03 is dissolved in JIS13B and measured on the surface. Acid silicone tree 28 200404904 Fat coating (made by Kansai Paint Co., SILICOTECT AC top coating, SILICOTECT AC TOP COAT) is completed by For a sample that was cut in the X shape from the top, a salt water spray test (5% NaC 1, 3.5 ° C, p Η 6) was performed for 1,000 hours in accordance with JISZ 2 3 71. · 5 ~ 7 · 2), and measure the time until significant flowing rust accumulates in the lower part of the sample. In addition, the dry film thickness of the coating is determined by using an electromagnetic film thickness meter using a magnetic method and a microscope method to confirm the cross-section of the coating film. It becomes about 5 0 // m. These measurement results are shown in Table 3. From Table 3, it is known that the steels 1 to 10 and steels 1 to 1 9 which are examples of the present invention are 50 J / cm2 in toughness (Shore impact value) regardless of the presence or absence of annealing of the hot-rolled sheet. It is 33% or more, and the reduction ratio is 75% or less. In addition, the salt water spray test at 1000 hours showed good corrosion resistance without generating flowing rust. On the other hand, Steel 1 1 to 17 which are comparative examples whose steel composition is outside the scope of the present invention cannot achieve good quality of at least one of the toughness, elongation, reduction ratio, and corrosion resistance regardless of the annealing of the hot rolled sheet. level. In addition, it has been confirmed that the effect of the present invention is obtained for some component steels by actual machine manufacturing using mass production equipment. 29 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904 Table 1 Steel plate surface removal amount (# m) Corrosion resistance of steel plate after coating Corrosion resistance inside steel plate-Cr concentration on steel surface (mass%) 5 Bad 4. 0 8 Bad 2.5 10 Good Good 1. 0 14 Good Good 0.8 8 20 Good Good 0.4 4 Good Good 0. 0 80 Good Good 0. 0 110 Good Good 0. 0 312 / Invention Manual (Supplement) / 92-11 / 92124190 200404904 ιε if # s ^ 4 5Φ4 f4s ^ 4 f4ff ^ 4 ¥ 4 5 ^^ 4 f # s ^ 4 5 ^^-4 f in antimony qq 90 · 0

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II 061 寸CNI(N6/l l-<N6/ff}®)_K^s,<NI £ 200404904 (w«)co< 本發明例本發明例本發明例本發明例本發明例本發明例本發明例本發明例本發明例比較例比較例比較例比較例比較例比較例比較例本發明例本發明例本發明例本發明例冷軋退火板之特性流動銹產生時間⑹ >1000 >1000 >1000 >1000 >1000 >1000 >1000 >1000 >1000 § o 另 >1000 >1000 >1000 >1000 >1000 >1000 >1000 >1000 >1000 降伏比(％ ) CO CO oo CD CD ο ο CD LO CD LO CO LO 00 (NI oo oo oo CO CD CO CO CD 延伸(％ ) CD CO LO CO CO LO CO CO oo oo LO CO 寸 CO 寸 CO ③ CO oo CO CO <NI oo CNI oo (NI oo CO oo CO oo CO 熱軋板(熱軋退火板)之特性蕭氏撞擊值 (J/cm2) ◦ r-H S g t-H g § T-H g t—H § § § 另 2 c=> 2 ο CD g (NI CD 流動銹產生時間⑸ >1000 >1000 >1000 >1000 >1000 >1000 >1000 >1000 >1000 导 g CO >1000 >1000 >1000 >1000 >1000 >1000 >1000 >1000 >1000 鋼板内部之Cr濃度(mass% ) LO CJ> 00 od 卜 od CNI ai CO cji LO od LO cd od CNI 呀· T-H r-H 13.5 (NI σί CD od T-H CD σί CO σ> cr> CO ai 鋼板表面之Cr濃度(mass% ) 1—4 CD t-H od CD od 呀 od od oo od CJ5 卜· r-H CD LO 卜： <0.1 ◦ CO t-H r-H 13.5 LO 〇〇· CNI 〇〇· LO od 卜 οό CO od ◦ CD o ai 鋼板表面除去量（，） LO LO LO LO LO LO l£D LO in LO LO LO in in !5 in LO 有無熱軋板退火碳碟碟碟 m 碟碟 #. 碟 m 4i 4i 杯杷碳碟鋼符號 οα CO 寸 LO CO 卜 oo CD r-H 23 oo 21 LO CD 卜 oo CJ5 oo -ee 髒 061 寸 HCN6/11 -(N6/ff-}*)_rH^^微/π e 200404904 (產業上之可利用性）本發明鋼係也有具有比較便宜之大優點。本發明鋼係比起SUS304或11% Cr不銹鋼，還可以藉由成為低Cr_低C —低N而省略熱軋板之退火；藉由熱軋板退火之省略而更進一步地達到成本降低。此外，活用本發明鋼之良好機械性質和低成本性，也能夠適用在以住宅構造材為首之各種住宅構造材之用途上，特別是在對於寒冷地之使用，發揮充分之性能。如果藉由本發明的話，則特別是達到所謂能夠供應具有充分之低溫韌性、耐撞擊性和耐蝕性並且更加便宜於不銹鋼之冷凍貨櫃用Cr鋼來作為冷凍貨櫃材之良好效果。【圖式簡單說明】圖1係顯示鋼板表面之除去量和SST(Salt Spray Testing ：鹽水喷霧試驗）銹面積率間之關係之圖。圖2A係鋼板表面除去量8#m之鋼板表面之掃描式電子顯微鏡相片。圖2B係鋼板表面除去量40/zm之鋼板表面之掃描式電子顯微鏡相片。圖3A係由藉著鋼板表面除去量8#m之藉由輝光放電分光分析所做的鋼板表面開始而顯示板厚方向之F e和C r濃度側面圖。圖3B係由藉著鋼板表面除去量40//Π1之藉由輝光放電分光分析所做的鋼板表面開始而顯示板厚方向之F e和C r濃度側面圖。 34 312/發明說明書(補件)/92-11 /92124190 200404904 圖4係顯示銹皮/鋼板界面之示意圖。 (元件符號說明） 1 鋼板表面除去量 2 錄皮/鋼板界面 3 内部氧化層 4 脫鉻層 5 銹皮層 6 優先氧化 7 氧化物形成 35 312/發明說明書(補件)/92-11/92124190II 061 inch CNI (N6 / l l- < N6 / ff) ®) _K ^ s, < NI £ 200404904 (w «) co < Examples of the invention Examples of the invention Examples of the invention Examples of the invention Examples of the invention Examples of the invention Example Inventive Example Inventive Example Inventive Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example > 1000 > 1000 > 1000 > 1000 > 1000 > 1000 > 1000 > 1000 § o another > 1000 > 1000 > 1000 > 1000 > 1000 > 1000 > 1000 > 1000 > 1000 Drop ratio (%) CO CO oo CD CD ο ο CD LO CD LO CO LO 00 (NI oo oo oo CO CD CO CO CD extension (%) CD CO LO CO CO LO CO CO oo oo LO CO inch CO inch CO ③ CO oo CO CO < NI oo CNI oo (NI oo CO oo CO oo CO Characteristics of hot-rolled sheet (hot-rolled annealed sheet) Xiao impact value (J / cm2) ◦ rH S g tH g § TH gt—H § § § Another 2 c = > 2 ο CD g (NI CD flow rust generation time ⑸ > 1000 > 1000 > 1000 > 1000 > 1000 > 1000 > 1000 > 1000 > 1000 g CO > 1000 > 1000 > 1000 > 1000 > 1000 > 1000 > 1000 > 1000 > 1000 Cr concentration inside the steel plate (mass%) LO CJ > 00 od Bud CNI ai CO cji LO od LO cd od CNI Yeh TH rH 13.5 (NI σί CD od TH CD σί CO σ > cr > CO ai Cr concentration on the surface of the steel plate (mass%) 1—4 CD tH od CD od od od oo od CJ5 LO Bu: < 0.1 ◦ CO tH rH 13.5 LO 〇〇 · CNI 〇〇 · LO od CO od ◦ CD o ai Steel plate surface removal (,) LO LO LO LO LO LO l £ D LO in LO LO LO in in! 5 in LO with or without hot-rolled sheet annealing carbon plate plate m plate plate #. plate m 4i 4i cup 杷 carbon plate steel symbol ο α CO inch LO CO oo CD rH 23 oo 21 LO CD oo CJ5 oo -ee Dirty 061 inch HCN6 / 11-(N6 / ff-} *) _ rH ^^ micro / π e 200404904 (industrial availability) The steel system of the present invention also has the great advantage of being relatively cheap. Compared with SUS304 or 11% Cr stainless steel, the steel of the present invention can further reduce the cost of the hot-rolled sheet by omitting the annealing of the hot-rolled sheet by becoming low-Cr_low-C-low-N; by omitting the annealing of the hot-rolled sheet. In addition, the good mechanical properties and low cost of the steel of the present invention can be applied to the use of various residential construction materials including residential construction materials, and in particular, it can exhibit sufficient performance in cold areas. According to the present invention, in particular, it is possible to achieve a good effect of using Cr steel as a refrigerated container material, which can provide so-called refrigerated containers with sufficient low-temperature toughness, impact resistance, and corrosion resistance, and which are cheaper than stainless steel. [Brief description of the drawing] Fig. 1 is a graph showing the relationship between the amount of steel plate surface removed and the rust area ratio of SST (Salt Spray Testing). Fig. 2A is a scanning electron microscope photograph of a steel plate surface with a surface removal amount of 8 # m. Fig. 2B is a scanning electron microscope photograph of a steel plate surface with a surface removal amount of 40 / zm. Fig. 3A is a side view showing the F e and C r concentrations in the thickness direction of the steel sheet starting from the surface of the steel sheet by a glow discharge spectroscopic analysis by removing 8 # m of the steel sheet surface. Fig. 3B is a side view showing the F e and C r concentration in the thickness direction of the steel plate starting from the surface of the steel plate by the glow discharge spectroscopic analysis by removing the steel plate surface by 40 // Π1. 34 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904 Figure 4 is a schematic diagram showing the scale / steel interface. (Description of component symbols) 1 Steel plate surface removal amount 2 Skin / steel interface 3 Internal oxide layer 4 Dechromization layer 5 Rust layer 6 Prior oxidation 7 Oxide formation 35 312 / Invention specification (Supplement) / 92-11 / 92124190

Claims

200404904 拾、申請專利範圍： 1. 一種構造用Cr鋼，其特徵為：含有mass(質量）％之 C ： 0.0 0 2 - 0.0 2 ¾ ' N ： 0.0 0 2 - 0.0 2 % > Si ： 0.05-1.0 % > Μη： 0.05-1.0% 、Ρ : 0 . 0 4 % 以下、S ·· 0· 0 2 % 以下、 A1: 0.001 〜0.1% 、Cr: 6.0〜10.0% ，由殘餘部 Fe 和不可避免之不純物所構成，鋼板表面之C r濃度（％ ) 2 (鋼板内部之Cr·濃度-1)(%)。 2 .如申請專利範圍第1項之構造用C r鋼，其中，還含有 mass(質量）％之 Cu: 0·1〜1.0% 。 3. 如申請專利範圍第1或2項之構造用C r鋼，其中，還含有由 mass(質量）％之 Ni: 0.1 〜1.0% 、Mo: 0.1 〜1.0 %中之所選擇出之1種或2種以上。 4. 如申請專利範圍第1至3項中任一項之構造用Cr鋼，其中，還含有由mass(質量）％之Nb: 0.005〜0.10% 、V: 0.005〜0.20 %中之所選擇出之1種或2種。 5. —種構造用Cr鋼熱軋鋼板之製造方法，其特徵為：藉由再加熱後之熱軋而使得含有mass(質量）％之C:0. 002 -0.02% ^ N ： 0 . 0 0 2 ~ 0 . 0 2 % 、Si: 0.05 〜：L0 % 、Μη: 0.05 〜1.0% 、Ρ: 0.04% 以下、S: 0.02% 以下、Α1: 0.001 〜 0 . 1 % 、C r : 6 , 0〜1 0 . 0 %且由殘餘部F e和不可避免之雜質所構成之鋼素材，成為鋼帶，接著，在進行脫銹皮處理之熱軋鋼板之製造步驟，藉由脫銹皮處理而除去鋼板表面10 〜2 0 0 // m 〇 6 . —種構造用C r鋼冷軋鋼板之製造方法，其係於申請 36 312/發明說明書(補件)/92-11/92124190 200404904 專利範圍第5項之方法中，在進行前述脫銹皮處理後，進行冷軋、冷軋鋼板退火和酸洗。 7. —種構造用C r鋼板之製造方法，其係於申請專利範圍第5或6項之方法中，前述鋼素材係還含有Cu: 0.1〜 1 . 0 °/〇。 8. —種構造用C r鋼板之製造方法，其係於申請專利範圍第5或6項之方法中，前述鋼素材係還含有由Ni: 0.1 〜1 . 0 % 、Μ 〇: 0 . 1〜1 . 0 %中之所選擇出之1種或2種以上。 9 . 一種構造用C r鋼板之製造方法，其係於申請專利範圍第5或6項之方法中，前述鋼素材係還含有由Nb:0.005 〜0.10 % 、V:0. 005〜0.20 %中之所選擇出之1種或2種。 1 0.如申請專利範圍第1至4項中任一項之構造用Cr 鋼，其中，前述鋼係冷凍貨櫃用。 1 1 .如申請專利範圍第5、7至9項中任一項之構造用C r 鋼熱軋鋼板之製造方法，其中，前述構造用Cr鋼板係冷凍貨櫃骨材用。 1 2 .如申請專利範圍第6、7至9項中任一項之構造用C r 鋼冷軋鋼板之製造方法，其中，前述構造用C r鋼板係冷凍貨櫃外覆材用。 1 3 . —種冷凍貨櫃，其特徵為：在申請專利範圍第1 0項，使用前述Cr鋼板，藉由成形和炼接而進行加工，並且，在該鋼板表面，具有乾燥膜厚1 0 // Hi以上之塗膜。 1 4 . 一種冷凍貨櫃，其特徵為：在申請專利範圍第1 1或 1 2項，使用藉由前述製造方法所製造之前述Cr鋼板，藉 37 312/發明說明書(補件)/92-11/92124190 200404904 由成形加工和熔接而進行成形加工，並且，在該鋼板表面，具有乾燥膜厚l〇#m以上之塗膜。 1 5.如申請專利範圍第1至4項中任一項之構造用Cr 鋼，其中，前述構造用Cr鋼係土木、建築構造用。 1 6.如申請專利範圍第5、7至9項中任一項之構造用C r 鋼熱軋鋼板之製造方法，其中，構造用C r鋼係土木、建築構造用。 1 7.如申請專利範圍第6、7至9項中任一項之構造用Cr 鋼冷軋鋼板之製造方法，其中，·構造用Cr鋼係土木、建築構造用。 38 312/發明說明書(補件)/92-11/92124190200404904 Scope of patent application: 1. A Cr steel for construction, which is characterized by containing C in mass (mass)%: 0.0 0 2-0.0 2 ¾ 'N: 0.0 0 2-0.0 2% > Si: 0.05 -1.0% > Μη: 0.05-1.0%, P: 0.04% or less, S ·· 0 · 02% or less, A1: 0.001 ~ 0.1%, Cr: 6.0 ~ 10.0%, Fe and Consisting of unavoidable impurities, the C r concentration (%) 2 on the surface of the steel sheet (Cr · concentration -1 inside the steel sheet) (%). 2. The Cr steel for construction according to item 1 of the scope of patent application, which further contains Cu: 0.1 to 1.0% by mass. 3. As for the Cr steel for structural use in item 1 or 2 of the patent application scope, it also contains one selected from mass (mass)% of Ni: 0.1 to 1.0% and Mo: 0.1 to 1.0%. Or 2 or more. 4. The Cr steel for construction according to any one of claims 1 to 3, which also contains the mass (mass)% of Nb: 0.005 ~ 0.10%, V: 0.005 ~ 0.20%. One or two. 5. A method for manufacturing a Cr steel hot-rolled steel sheet for a structure, characterized in that by hot rolling after reheating, C: 0.002 -0.02% ^ N: 0. 0 containing mass (mass)% 0 2 to 0.02%, Si: 0.05 to: L0%, Mn: 0.05 to 1.0%, P: 0.04% or less, S: 0.02% or less, A1: 0.001 to 0.1%, Cr: 6,, 0 ~ 1 0. 0% of the steel material composed of the residual Fe and unavoidable impurities becomes a steel strip, and then, in a manufacturing step of a hot-rolled steel sheet subjected to descaling treatment, the descaling treatment is performed. The surface of the steel plate is removed from 10 to 2 0 0 // m 〇6. — A method for manufacturing a Cr steel cold-rolled steel plate for construction, which is based on the application for 36 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904 Patent In the method of the range 5 item, after performing the said descaling process, cold rolling, cold-rolled steel sheet annealing, and pickling are performed. 7. A method for manufacturing a Cr steel plate for construction, which is the method in the scope of claims 5 or 6 of the patent application, and the aforementioned steel material further contains Cu: 0.1 to 1.0 ° / 〇. 8. A method for manufacturing a Cr steel plate for construction, which is the method in the scope of the patent application No. 5 or 6, wherein the aforementioned steel material further contains Ni: 0.1 to 1.0%, and 〇: 0.1. 1% or more selected from ~ 1.0%. 9. A method for manufacturing a Cr steel plate for construction, which is the method in the scope of claim 5 or 6, in which the aforementioned steel material further contains Nb: 0.005 to 0.10%, V: 0.005 to 0.20%. Choose one or two. 10. The Cr steel for construction according to any one of claims 1 to 4, wherein the aforementioned steel is used for refrigerated containers. 1 1. The method for manufacturing a Cr steel hot-rolled steel sheet for construction according to any one of claims 5, 7 to 9, wherein the Cr steel sheet for the construction is used for a frozen container aggregate. 1 2. The method for manufacturing a Cr steel cold-rolled steel sheet for construction according to any one of claims 6, 7 to 9, wherein the Cr steel sheet for the aforementioned construction is used for the outer covering of a frozen container. 1 3. A refrigerated container, characterized in that: in the scope of patent application No. 10, the aforementioned Cr steel plate is used for processing by forming and smelting, and the surface of the steel plate has a dry film thickness of 10 / / Coating film above Hi. 1 4. A refrigerated container, characterized in that in the scope of patent application No. 11 or 12, the aforementioned Cr steel plate manufactured by the aforementioned manufacturing method is used, borrowing 37 312 / Invention Specification (Supplement) / 92-11 / 92124190 200404904 The forming process is performed by forming and welding, and the surface of the steel sheet has a coating film with a dry film thickness of 10 # m or more. 1 5. The Cr steel for construction according to any one of claims 1 to 4, wherein the Cr steel for the aforementioned construction is used for civil engineering and building construction. 1 6. The method for manufacturing a Cr steel hot-rolled steel sheet for construction according to any one of claims 5, 7 to 9, wherein the Cr steel for construction is used for civil engineering and building construction. 1 7. The method for manufacturing a cold-rolled steel sheet for Cr steel for construction according to any one of claims 6, 7 to 9, in which: Cr steel for construction is used for civil engineering and building construction. 38 312 / Invention Specification (Supplement) / 92-11 / 92124190