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Q/BQB 420-2023 PDF English (Q/BQB 420-2021: Older version)Search result: Q/BQB 420-2023 (Q/BQB 420-2021 Older version)
Q/BQB420-2023 (QBQB420-2023): PDF in EnglishQ/BQB 420-2023 BQB® ENTERPRISE STANDARD OF BAOSTEEL CO., LTD. Replacing Q/BQB 420-2021 Hot-dip zinc /zinc-iron /zinc-magnesium /zinc-aluminum- magnesium alloy coated steel sheet and strip ISSUED ON: APRIL 09, 2023 IMPLEMENTED ON: JULY 01, 2023 Issued by: BaoSteel Co., Ltd. Table of Contents Foreword ... 3 1 Scope ... 5 2 Normative references ... 5 3 Terms and definitions ... 6 4 Classification and code ... 9 5 Information required for ordering ... 11 6 Dimensions, appearance, weight, allowable deviations ... 12 7 Technical requirements ... 13 8 Inspection and testing ... 26 9 Packaging, marking, inspection documents ... 28 10 Numerical rounding rules ... 28 11 Comparison of similar designation ... 28 Appendix A (Normative) Permissible deviations in thickness and unevenness of steel sheet and strip (hot-rolled pickled substrates) ... 29 Appendix B (Normative) Weight calculation method in theoretical weighing ... 32 Appendix C (Normative) Chemical composition of steel ... 33 Appendix D (Informative) Comparison of similar designations between this document and relevant domestic and foreign documents ... 37 Hot-dip zinc /zinc-iron /zinc-magnesium /zinc-aluminum- magnesium alloy coated steel sheet and strip 1 Scope This document specifies the requirements for terms and definitions, classification and codes, dimensions, appearance, weight, technical requirements, inspection and testing, packaging, marking and inspection documents of the hot-dip zinc /zinc-iron /zinc- magnesium /zinc-aluminum-magnesium alloy coated steel sheet and strip (hereinafter referred to as steel sheet and strip). This document applies to steel sheet and strip, which has a thickness of 0.23 mm ~ 4.00 mm, as produced by Baoshan Iron and Steel Co., Ltd. They are mainly used to make internal and external covering parts and structural parts in the automobile, construction, home appliances and other industries. 2 Normative references The contents of the following documents constitute essential provisions of this document through normative references in the text. Among them, for dated reference documents, only the version corresponding to the date applies to this document; for undated reference documents, the latest version (including all amendments) applies to this document. GB/T 222 Method of sampling steel for determination of chemical composition and permissible variations for product analysis GB/T 223 Methods for chemical analysis of iron, steel and alloy GB/T 228.1-2021 Metallic materials - Tensile testing - Part 1: Method of test at room temperature GB/T 232 Metallic materials - Bend test GB/T 1839 Test method for gravimetric determination of the mass per unit area of galvanized coatings on steel products GB/T 2523 Measuring method of surface roughness, peak count and waviness for cold-rolled metal sheet and strip GB/T 2975 Steel and steel products - Location and preparation of samples and test 3.2 Hot-dip zinc-iron alloy coating (ZF) On a hot-dip zinc production line, the coating which is obtained by immersing pre- treated steel strips in molten zinc. The zinc content in the molten zinc liquid shall be no less than 99%. Subsequently, a zinc-iron alloy layer is formed on the entire coating through an alloying process. The iron content in the alloy coating is usually 8 ~ 15%. 3.3 Hot-dip zinc-magnesium alloy coating (ZM) On a hot-dip zinc production line, the coating which is obtained by immersing the pretreated steel strip in a molten zinc solution containing aluminum and magnesium. The mass percentage of magnesium in the molten zinc-magnesium alloy solution is 1.0 ~ 2.0%; the mass percentage of aluminum is 0.8 ~ 3.0%; the mass percentage of other trace control elements is less than 1%; the remaining components are zinc. 3.4 Hot-dip zinc-aluminum-magnesium alloy coating (XM) On a hot-dip zinc production line, the coating which is obtained by immersing the pretreated steel strip in a molten zinc solution containing aluminum and magnesium. The mass percentage of magnesium in the molten zinc-aluminum-magnesium alloy solution is 2.0 ~ 4.0%; the mass percentage of aluminum is 5.0 ~ 7.0%; the mass percentage of other trace control elements is less than 1%; the remaining components are zinc. 3.5 Interstitial free steels Interstitial-free steel is a type of steel in which an appropriate amount of titanium or niobium is added to ultra-low carbon steel, so that the carbon and nitrogen interstitial atoms in the steel are completely fixed into carbon and nitride, meanwhile there are no interstitial atoms in the steel. 3.6 High strength interstitial free steels (Y) The plastic strain ratio (r value) and strain hardening index (n value) of steel are improved, by controlling the chemical composition of the steel. Due to the solid solution strengthening of the elements in the steel and the interstitial-free microstructure, this steel has both high strength and very good cold forming properties, so it is often used to make complex parts that require deep drawing. 3.7 Bake hardening steels (B) A certain amount of solid solution carbon and nitrogen atoms are retained in low carbon steel or ultra-low carbon steel, meanwhile solid solution strengthening elements such as phosphorus and manganese may be added, to improve the strength. After processing and forming, after baking at a certain temperature, the yield strength of the steel further increases due to age hardening. 3.8 High strength low alloy steels (LA) In low carbon steel or ultra-low carbon steel, micro-alloying elements such as niobium, titanium, vanadium are added singly or in combination, to form carbonitride particles and precipitate for strengthening. At the same time, higher strength is obtained through the refinement of grains by micro-alloying elements. 3.9 Dual phase steels (DP) The microstructure of steel is mainly ferrite and martensite, wherein the martensite structure is dispersed in an island shape on the ferrite matrix. Duplex steel has a low yield-to-strength ratio, high work hardening index, bake hardening value, which is one of the preferred materials for structural parts. 3.10 Transformation induced plasticity steels (TR) The microstructure of steel is ferrite, bainite, retained austenite, of which the content of retained austenite is at least 5%. During the forming process, retained austenite can transform into martensite structure, which has high work hardening rate, uniform elongation, tensile strength. Compared with dual-phase steel with the same tensile strength, it has higher elongation. 3.11 Complex phase steels (CP) The microstructure of steel is mainly ferrite and/or bainite. On the ferrite and/or bainite matrix, a small amount of martensite, retained austenite and pearlite are usually distributed. By adding micro-alloying elements Ti or Nb, the effect of grain refinement or precipitation strengthening is achieved. This steel has very high tensile strength. Compared with dual-phase steel with the same tensile strength, its yield strength is significantly higher. This steel has a high energy absorption capacity and a high residual strain capacity. 3.12 Quenching and partitioning steel (QP) Steel is a type of ultra-high-strength steel with high formability, as produced using the quenching-partitioning process. The microstructure of steel is composed of a multi- phase composite of martensite + ferrite + retained austenite. By utilizing the ultra-high strength brought by martensite and the transformation-induced plasticity (TRIP) effect of retained austenite, it can obtain better formability than traditional ultra-high-strength steel. QP steel is age-free, which has a medium yield-to-strength ratio and high work- hardening properties; it is suitable for vehicle frame parts and safety parts, which have relatively complex shapes and high strength requirements. 3.13 Dual phase high ductility steels (DH) The microstructure of steel is mainly composed of ferrite, martensite, a small amount of retained austenite and bainite. Compared with DP steel of the same strength level, it 6.2 The allowable deviations in size and shape of steel sheet and strip, which is produced from cold-rolled substrates, shall comply with the provisions of Q/BQB 401. The thickness tolerance of steel sheet and strip which has a designation of S550GD+Z/ZM/XM shall comply with the requirements of Table 4 in Q/BQB 401- 2023 (specifying minimum yield strength 260 MPa ~ < 360 MPa); the maximum allowable deviation of unevenness shall comply with the requirements of Table 11 in Q/BQB 401-2023 (specifying minimum yield strength 260 MPa ~ < 360 MPa). The allowable deviations of thickness and unevenness of steel sheet and strip, which is produced from hot-rolled pickled substrates, shall comply with the provisions of Appendix A (Normative); the allowable deviations of width, length and other shapes shall comply with the provisions of Q/BQB 401. 6.3 Steel sheets are usually delivered according to theoretical weight. However, they may also be delivered according to actual weight. The calculation method of the theoretical weight of steel sheets shall comply with the provisions of Appendix B (Normative). Steel strips are usually delivered according to actual weight. 7 Technical requirements 7.1 Chemical composition The chemical composition (smelting analysis) of steel shall comply with the provisions of Appendix C. The allowable deviation of the chemical composition of finished steel sheet and strip shall comply with the provisions of GB/T 222. If the buyer has special requirements for chemical composition, these shall be negotiated when ordering. 7.2 Smelting methods The steel used for steel sheet and strip is smelted in an oxygen converter. 7.3 Delivery status Normally, steel sheet and strip are delivered after being hot-dip galvanized and smoothed. 7.4 Mechanical properti.......Source: https://www.ChineseStandard.net/PDF.aspx/QBQB420-2023 |