Translated English of Chinese Standard: Q/BQB440-2014 www.chinesestandard.net Sales@ChineseStandard.net SUPPLY TECHNICAL CONDITIONS OF BAOSHAN IRON & STEEL CO., LTD. Q/BQB Q/BQB 440-2014 Replacing Q/BQB 404-2009 Prepainted steel sheets and strips 彩色涂层钢板及钢带 Issued on: October 18, 2014 Implemented before: March 31, 2015 Issued by: Baoshan Iron & Steel Co., Ltd. www.chinesestandard.net Page 1 of 33
Table of Contents 1 Scope... 4 2 Normative references... 4 3 Terms and definitions... 5 4 Classifications and codes... 6 5 Order required information... 7 6 Size, appearance, weight and tolerance... 8 7 Technical requirements... 8 8 Inspection and test... 13 9 Packaging, marks and inspection documents... 15 10 Transport, storage, processing... 15 11 Numerical correction rule... 15 12 Description of the corrosion of the environment of use... 16 13 Selections of prepainted steel sheet... 16 14 Prepainted steel sheet s storage, transport and loading-unloading... 16 15 Prepainted steel sheet s processing... 16 16 Life to the first major maintenance and durability of prepainted steel sheet... 16 17 Air exposure test field of prepainted steel sheet... 16 Annex A (Informative) Description of the corrosion of the environmental of use... 17 Annex B (Informative) Selection of prepainted steel sheet... 21 www.chinesestandard.net Page 2 of 33
Annex C (Informative) Storage, transport and loading-unloading of prepainted steel sheet... 25 Annex D (Informative) Processing of prepainted steel sheet... 27 Annex E (Informative) Life to the first major maintenance and durability of prepainted steel sheet... 29 Annex F (Informative) Air exposure test field of prepainted steel sheet... 30 www.chinesestandard.net Page 3 of 33
Prepainted steel sheets and strips 1 Scope This Technical Conditions specifies the terms and definitions, classifications and codes, size, appearance, weight, technical requirements, inspection and testing, packaging, marking and inspection documents of prepainted steel sheet and strips (hereinafter referred to as prepainted steel sheet). This Technical Conditions is applicable to the building prepainted steel sheets that are manufactured by Baoshan Iron & Steel Co., Ltd., of thickness of 0.22 mm ~ 2.0 mm. The industries of home appliance, furniture, steel window can refer to use. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. GB/T 1766-2008, Paints and Varnishes-Rating Schemes of Degradation of Coats GB/T 8170-2008, Rules of rounding off for numerical values & expression and judgement of limiting values GB/T 13448-2006, Test methods for prepainted steel sheet GB/T 15957-1995, Corrosivity classification of atmospheric environment GB/T 19292.1-2003, Corrosion of metals and alloys - Corrosivity of atmospheres - Classification Q/BQB 400, Packaging, marks and inspection documents of cold-rolled products Q/BQB 420, Hot-dip galvanized / zinc-iron alloy coated steel sheet and strip Q/BQB 425, Hot-dip galvanized alloy steel sheet and strip Q/BQB 430, Galvanized steel sheet and strip www.chinesestandard.net Page 4 of 33
3 Terms and definitions 3.1 prepainted steel sheet the product of which the organic coating (the top side is at least two layers) is continuously coated on the surface-pretreated substrate and then is baked and cured 3.2 steel substrate the steel strip used for coating painting 3.3 top side usually referring to the higher demanding side on color, coating performance, surface quality in the two sides of prepainted steel sheet; when delivered in roll, it usually refers to the outside of the prepainted steel coil 3.4 bottom side the opposite side to the top side of prepainted steel sheet 3.5 building exterior applications the applications mainly affected by building external atmosphere 3.6 building interior applications the applications mainly affected by building internal atmosphere 3.7 hardness the ability of coating to resist to scratch, friction, collision, press and other mechanical effects 3.8 flexibility the ability of the coating to co-deform with the substrate without damage 3.9 adhesion the firmness between coatings or between coating and substrate 3.10 life to the first major maintenance the interval FROM the end of production TO the time when the performance of original coating degrades then major maintenance must be carried out so as to continue protecting the substrate www.chinesestandard.net Page 5 of 33
comply with the provisions of Table 4. Special requirements for pencil hardness shall be negotiated at the time of order. 7.2.3 Coating gloss 7.2.3.1 The coating gloss is represented by 60 mirror gloss. The gloss is divided into low, medium and high grades. The nominal value of gloss at all grades shall be in accordance with the provisions of Table 4. 7.2.3.2 The gloss of three samples shall comply with corresponding provisions of Table 4. For low gloss coating, the gloss tolerance is ± 3 gloss units. For medium gloss coating, the gloss tolerance is ± 10 gloss units. For high gloss coating, the gloss tolerance is 0 ~ -10 gloss units. 7.2.3.3 The difference in gloss per batch of product shall not exceed 10 gloss units. 7.2.4 Coating flexibility / adhesion 7.2.4.1 The coating flexibility / adhesion is usually evaluated by bending test and reverse impact test. If the cross-grid test, cup sudden test, etc. are required for further evaluation, it shall be negotiated at the time of order. 7.2.4.2 Bending test 7.2.4.2.1 Three sample values of bending test shall comply with the corresponding provisions of Table 4. Special requirements for bending test shall be negotiated at the time of order. 7.2.4.2.2 After the bending sample is stripped off by tape, there shall be no coating peeling off at the bend, excluding the coating falling off within 10 mm from the sample edges. If non-visible cracks are required at the bend, it shall be negotiated at the time of order. 7.2.4.2.3 The prepainted steel sheets are usually supplied in A-level T-bend. B-level T-bend performance shall be negotiated at the time of order. Steel windows are usually supplied in accordance with the B-level T-bend. For prepainted steel sheets of which the designations are TS550GD+Z and TS550GD+AZ, T-bend performance is not required. If there are special requirements for T-bend performance, it shall be negotiated at the time of order. 7.2.4.3 Reverse impact test 7.2.4.3.1 The minimum value of reverse impact test s three samples shall comply with the provisions of Table 4. Special requirements for impact energy shall be negotiated at the time of order. www.chinesestandard.net Page 10 of 33
7.2.4.3.2 After the reverse impact test sample is peeled off by tape, there shall be no coating peeling off in the deformation area. If non-visible cracks are required at the deformation area, it shall be negotiated at the time of order. 7.2.4.3.3 For prepainted steel sheets of which the thickness is less than 0.40 mm and designations are TS550GD+Z, TS550GD+AZ, the reverse impact test is not required. 7.2.5 Coating durability 7.2.5.1 The coating durability is usually evaluated by the resistance to neutral salt spray test or the ultraviolet lamp accelerated weathering test. If the xenon lamp accelerated weathering test, heat resistance and resistance to sulfur dioxide hot and humid test are required for further evaluation, it shall be negotiated at the time of order. 7.2.5.2 Resistance to neutral salt spray test 7.2.5.2.1 The time of the resistance to neutral salt spray test of coating shall comply with the provisions of Table 4. Special requirements for test time shall be negotiated at the time of order. 7.2.5.2.2 Within the specified time of neutral salt spray test, the bubble density level and bubble size rating of unmarked sample shall not exceed grade 3 specified in Table 21 of GB/T 1766. 7.2.5.3 Ultraviolet lamp accelerated weathering test 7.2.5.3.1 The time of ultraviolet lamp accelerated weathering test of coating shall comply with the provisions of Table 4. Special requirements for test time shall be negotiated at the time of order. 7.2.5.3.2 Within the test time specified in Table 4, the sample should be free of foam, cracks. Powdery shall not exceed grade 1 specified in GB/T 1766. 7.2.5.3.3 When the coating is polyester and silicon-modified polyester, it is usually evaluated with UVA-340. If UVB-313 is used for evaluation, it shall be indicated at the time of order. When the coating is high durability polyester and polyvinylidene fluoride, it is usually evaluated with UVA-313. If UVB-340 is used for evaluation, it shall be indicated at the time of order. 7.2.5.4 If the supplier can guarantee, the inspections of coating s resistance to neutral salt spray and ultraviolet lamp accelerates weathering performance can be exempted. 7.2.6 Coating color difference www.chinesestandard.net Page 11 of 33
results (including all indicators required by the test of this item) fail, the re-inspection shall be regarded as unqualified. If the re-inspection is not qualified, the single piece that has been tested and test result fails shall not be accepted. However, the single pieces in this batch of material that has not been tested can be re-submitted one by one for testing and acceptance. 9 Packaging, marks and inspection documents 9.1 The packaging, marks and inspection documents of prepainted steel sheets shall be in accordance with the provisions of Q/BQB 400. Special requirements of purchaser on packaging shall be indicated in the contract. 9.2 The top coat types and colors shall be indicated in the inspection documents and marks of prepainted steel sheets. 10 Transport, storage, processing 10.1 Pay attention to make the prepainted steel sheets from damage on the coating surface, dampness during transport, loading-unloading, storage, processing. Store in the indoor warehouse. 10.2 To prevent coating performance degrades during low temperature processing, the steel plate and strip forming processing shall be carried out at room temperature. 10.3 The processing performance of the coating shall be degraded with the storage time. Therefore, it is recommended that the user processes and uses within one year from the date of manufacture. 10.4 When steel sheet and strip are used for production of sandwich panels, considering the user s binder, the matching between production process and steel sheet and strip, it is recommended to carry out small batch test first. 10.5 For products of which the coating type is polyvinylidene fluoride, its coating characteristics are special. It is recommended that the user cover the plastic film during processing so as to reduce the risk of coating shedding. 11 Numerical correction rule The numerical correction rule shall comply with the provisions of GB/T 8170. www.chinesestandard.net Page 15 of 33
12 Description of the corrosion of the environment of use It is shown in Annex A. 13 Selections of prepainted steel sheet It is given in Annex B. 14 Prepainted steel sheet s storage, transport and loading-unloading It is given in Annex C. 15 Prepainted steel sheet s processing It is given in Annex D. 16 Life to the first major maintenance and durability of prepainted steel sheet It is given in Annex E. 17 Air exposure test field of prepainted steel sheet It is given in Annex F. www.chinesestandard.net Page 16 of 33
A.3 Corrosion of atmospheric environment A.3.1 Key factors affecting the prepainted steel sheet s resistance to atmospheric corrosion are the type and concentration of corrosive media in the atmosphere, the time when coating surface is covered with moist film, i.e., wet time. The more types of corrosive media, the higher the concentration, the longer the wet time, the higher the atmospheric corrosion. A.3.2 GB/T 15957, according to corrosive medias (mainly sulfur dioxide and chloride) present in the atmosphere and their concentrations, classifies the atmospheric environment into four types: rural atmosphere, urban atmosphere, industrial atmosphere and ocean atmosphere. However, the actual atmospheric environment is complex and diverse, and there may be a variety of corrosive medias such as hydrogen sulfide, hydrogen fluoride, nitrogen oxides, industrial dust, so the atmospheric environment classification in GB/T 15957 is not perfect because it is impossible to include all the atmospheric environment, which should be fully understood. In addition, in particular operating environment, such as chemical plants, smelters, thermal power plants and other places around the atmospheric environment, i.e., the micro-environment may be greatly different with the atmosphere of that area. At this point the micro-environment may be more important than the atmospheric environment. Therefore, it shall make accurate judgments on the corrosion of micro-environment as much as possible and pay special attention during the analysis on the atmospheric corrosion. A.3.3 Wet time depends on climatic conditions such as relative humidity, temperature, light time, wind and other factors. The formation of wet film is usually related to the following factors: a) atmospheric relative humidity increases; b) the surface temperature of the coating reaches the dew point or dew point below the condensation; c) the coating surface deposition of moisture absorption material; d) the coating surface is directly wetted by the condensation of moisture, rain, snow, etc.; taking measures such as ventilation, drying, cleaning, etc. can reduce the formation of wet film, shorten the wet time. A.4 Corrosion of internal atmosphere A.4.1 Same with the corrosion of atmospheric environment, the key factors affecting the prepainted steel sheet s resistance to internal atmospheric corrosion are the type and concentration of corrosive media in the atmosphere, the time when coating surface is covered with moist film, i.e., wet time. The more types of corrosive media, the higher the concentration, www.chinesestandard.net Page 18 of 33
Annex B (Informative) Selection of prepainted steel sheet B.1 Reasonable material selection can not only meet the requirements, but also to minimize the cost. If the material is improper, the result may be that the material performance exceeds the use requirements, resulting in unnecessary waste; it may not meet the requirements, resulting in downgrade or can not be used. Therefore, the purchaser shall pay great attention to the importance of rational selection, if necessary, consult the relevant experts. B.2 The selection of prepainted steel sheet mainly refers to mechanical properties, substrate type and coating weight, top side coating performance and bottom side coating performance. The use, the corrosion of environment of use, the life to the first major maintenance, durability, processing method and the degree of deformation are important factors during material selecting. B.3 Selection of mechanical properties, substrate type and coating weight B.3.1 Mechanical properties are selected mainly based on the use, processing method and the degree of deformation, etc. When the strength requirements are not high, deformation is not complicated, TDC51D, TDC52D series of prepainted steel sheet can be used. When there is a high demand for formability, TDC53D, TDC54D series of prepainted steel sheet shall be selected. For the load-bearing components, it shall be based on design requirements to select the appropriate structural steel, such as TS280GD, TS350GD series of prepainted steel sheet. Cutting, bending, rolling, etc. are commonly used processing methods for prepainted steel sheet. Order should be based on the characteristics of each processing method. In actual production, the mechanical properties of the prepainted steel sheet are usually replaced by the mechanical properties of the substrate while prepainting process may cause the change of mechanical properties of the substrate. In addition, mechanical properties may also vary with storage time. These shall increase the possibility of Ruth band or crease during the processing and forming of prepainted steel sheet, which shall be noted. B.3.2 Substrate type and coating weight are selected based on factors such as the use, corrosion of the environment, life to the first major maintenance and durability. Anti- corrosion is one of the main functions of prepainted steel sheet. Substrate type and coating weight are the main factors that affect the corrosion resistance of prepainted steel sheet. Building application prepainted steel sheet usually select hot-dip galvanized substrate and hot-dip www.chinesestandard.net Page 21 of 33
detailed performance indicators of a variety of primers can refer to the relevant information or expert advice. The primer is usually selected by the supplier according to the production process, the use, the corrosion of the environment, and the matching relationship with the finish. B.4.3 Coating thickness The coating thickness is closely related to the corrosion resistance of prepainted steel sheet. Corrosion resistance usually increases with increasing coating thickness. At the time of order, the appropriate coating thickness shall be determined according to the corrosion of the environment of use, the life to the first major maintenance and durability. B.4.4 Coating color difference The prepainted steel sheet may have color difference during the process of production and use. Since the color difference is affected by the manufacturer, the color depth, the use time, the use environment, the use, it is usually negotiated by both parties at the time of order. B.4.5 Coating gloss The coating gloss is selected mainly according to the use and usage habit. For example, building application prepainted steel sheet usually selects medium, low glosses; home appliance application prepainted steel sheet usually selects high gloss. B.4.6 Coating hardness The coating hardness is the ability of the coating to resist mechanical scratches, friction, impact, press, etc., closely related to scratch resistance, abrasion resistance, resistance to indentation of prepainted steel sheet, selected mainly based on the use, processing, storage and transportation conditions. B.4.7 Coating flexibility / adhesion The flexibility / adhesion of the coating is closely related to the workability of prepainted steel sheet, selected mainly based on processing mode, deformation degree. When the deformation speed is high, deformation degree is great, it shall select the prepainted steel sheet of great impact energy and small T-bend value. B.4.8 Coating durability Coating durability is a performance of prepainted steel sheet during use, usually measured by the length of the life to the first major maintenance. The coating durability is closely related to the type of coating, the thickness of the www.chinesestandard.net Page 23 of 33
Annex C (Informative) Storage, transport and loading-unloading of prepainted steel sheet C.1 Storage, transport and loading-unloading are important parts affecting the quality of prepainted steel sheet. The improper operation may cause scratches, embossing, corrosion and other defects during the storage, transport and loading-unloading. In order to minimize and avoid the generation of defects, the following operational considerations are described as follows. Specific provisions on storage, transport and loading-unloading can refer to relevant information or expert consultation. C.2 Storage a) The prepainted steel sheet shall be stored in a clean and neat environment, so as to avoid the erosion from a variety of corrosive medias. b) The storage site should be flat, free of hard objects and have sufficient load capacity. c) Horizontal steel coil should be placed on rubber mat, bed timber, bracket or other devices. The straps should be locked upwards and can not be placed directly on the ground or on the means of transport. d) In order to avoid crushing, the coil is usually not stacked. Steel sheet stacking should be strictly limited on stacking layer, placing the ones of great weight and size at the bottom. e) The product should be stored in a dry, ventilated indoor environment, so as to avoid the open storage or storage in the prone to condensation and temperature changes in large place. f) There should be sufficient space for the storage site to be used for lifting equipment. g) The storage location for steel sheet and coil should be arranged reasonably so as to facilitate the use of the vehicle and minimize unnecessary movement as much as possible. h) It should be noted that the mechanical properties and coating properties of the prepainted steel sheet may vary with storage time. C.3 Transport and loading-unloading www.chinesestandard.net Page 25 of 33
Annex D (Informative) Processing of prepainted steel sheet D.1 Processing is an important part affecting the quality of prepainted steel sheet. In order to ensure product quality, the following operational considerations during processing are described as follows. Specific provisions on the processing may refer to the relevant information or consult with the experts. D.2 Because the prepainted steel sheet has coating on its surface, there are many differences during processing between it and ordinary cold rolled sheet and coated board. The main difference is that the forming and processing can be carried out under the premise of coating in good condition. The precautions for processing are as follows: a) mechanical properties (such as yield strength, tensile strength, elongation) is an important measure of formability, an important parameter of determination and adjustment of processing technology, one of the main factors to be considered when processing; b) coating performance (such as pencil hardness, T-bend value, impact energy) is closely related to the processing performance, which is another main factor to be considered when processing; c) partial mechanical properties (such as yield strength, elongation) and partial coating properties (such as pencil hardness, T-bend value, impact energy) of prepainted steel sheet are usually vary with storage time, which shall affect the processing and forming and should be given sufficient attention; d) when the shape of the component is complicated and the degree of deformation is large, it shall use multi-pass forming. once forming may destroy the adhesion of coating due to too large deformation; e) set the appropriate gap according to factors such as mold shape, deformation characteristics, process conditions when processing; the gap setting shall consider the thickness of coating; f) most coatings can be used as solid lubricants and can meet the lubrication requirements of most forming processes; some paints can improve the lubricity of the coating by adjusting the formulation. If the coating is not lubricated, it can be lubricated by oiling, waxing, coating, www.chinesestandard.net Page 27 of 33
covering with peelable protective film, etc. But it should be noted that the wet lubricant is easy to absorb dirt, which should be cleared before installation. The peelable protective film should also be removed as soon as possible after processing; g) set reasonable processing speed according to equipment conditions, process conditions, component shape because if deformation speed is to high, it shall easily lead to coating peeling off. When the temperature is low, the flexibility of the coating shall be reduced; therefore, it shall avoid low temperature processing. If the ambient temperature is low, the material should be preheated to a certain temperature and then processed; h) the cut-out section produced during processing is susceptible to corrosion. Therefore, the necessary protective measures should be taken, such as coating the protective coating, embedding seal, etc.; i) it shall minimize the cutting of the burrs to prevent the surface scratch by burrs during processing; j) it shall keep all surfaces in contact with the coating clean and tidy. Timely clean the chips and metal particles produced during processing to prevent the coating surface from damage by foreign objects; k) it shall minimize the wear of the roll surface or mold surface when processing, maintain the contact surface clean and smooth, prevent the surface from the coating indentation, scratches and other defects; l) it shall use the construction method as possible: factory pre-assembly then site installation. Protective measures should be taken during installation to prevent damage to the coating; m) when processing, if coating surface damage is found, it shall timely use special repair paint to repair so as to prevent the damaged part from corrosion. www.chinesestandard.net Page 28 of 33
Annex F (Informative) Air exposure test field of prepainted steel sheet F.1 At present, there are many sites in China that can be tested for color exposure. This Technical Conditions selected some test fields from National Material Environmental Corrosion Test Station Network as references. Other suitable test sites can also be selected if necessary. F.2 Introductions of some atmospheric exposure test sites in China F.2.1 Beijing atmospheric exposure test site Beijing atmospheric exposure test site is located in the western suburbs of Beijing. The annual average temperature in this region is not high, the temperature difference is great and the humidity is not high. Because it is in the suburban rural environment, so there are less pollutants in the atmosphere. It can be used as the test site of warm temperate sub-humid rural climate area F.2.2 Shenyang atmospheric exposure test site Shenyang atmospheric exposure test site is located in Shenyang city. The annual average temperature in this region is low, the temperature difference is great and the humidity is not high. Since it is in the urban area, sulfur dioxide, nitrogen oxides shall be as the main air pollutants. It can be used as the test site of medium-temperate sub-humid city climate area. F.2.3 Hailar atmospheric exposure test site Hailar atmospheric exposure test site is located in outskirts of Inner Mongolia Autonomous Region Hailar. The annual average temperature in this region is low, the temperature difference is great, the humidity is not high, sunshine duration is long and radiation is strong. Because it is in the grassland area, the perennial wind speed is high; the air is fresh. It can be used as the test site of medium-temperate sub-arid rural climate area. F.2.4 Qingdao atmospheric exposure test site Qingdao atmospheric exposure test site is located in the Wheat Island, Qingdao. The annual average temperature in this region is not high, the temperature difference is not great and the humidity is medium. It is in the sea-surrounding area, so he sea salt content in the atmosphere is high. It can www.chinesestandard.net Page 30 of 33
be used as the test site of warm temperate humid marine climate area. F.2.5 Wuhan atmospheric exposure test site Wuhan atmospheric exposure test site is located in Wuhan city. The annual average temperature in this region is high, the temperature difference is not great and the humidity is high. Since it is in the urban area, sulfur dioxide, nitrogen oxides shall be as the main air pollutants. It can be used as the test site of north subtropical humid urban climate area. F.2.6 Guangzhou atmospheric exposure test site Guangzhou atmospheric exposure test site is located in Huadu District of Guangzhou. The annual average temperature in this region is high, the temperature difference is little and the humidity is high, the sunshine duration is not long but the radiation is strong. Because it is close to the urban area, it also has a certain degree of air pollution. It can be used as the test site of south subtropical humid urban climate area. F.2.7 Qionghai atmospheric exposure test site Qionghai atmospheric exposure test site is located in the suburb of Qionghai, Hainan Province. The annual average temperature in this region is high, the temperature difference is little and the humidity is high, the sunshine is abundant and the radiation is strong. Because it is in the rural area, there are less air pollutants. It can be used as the test site of north tropical humid rural climate area. F.2.8 Wanning atmospheric exposure test site Wanning atmospheric exposure test site is located at the seaside of Wanning City, Hainan Province. The annual average temperature in this region is high, the temperature difference is little and the humidity is high, the sunshine is abundant and the radiation is strong. Because it is close to the sea, the content of sea salt particles in the atmosphere is high. It can be used as the test site of north tropical humid marine climate area. F.2.9 Jiangjin atmospheric exposure test site Jiangjin atmospheric exposure test site is located in the Jiangjin suburb, Chongqing. The annual average temperature in this region is high, the temperature difference is not great and the humidity is high. The high sulfur dioxide content in the atmosphere, acid rain corrosion are significant features of this region. It can be used as the test site of mid-subtropical humid acid rain climate area. F.2.10 Dunhuang atmospheric exposure test site www.chinesestandard.net Page 31 of 33