Q/BQB 420-2023 Hot-dip zinc / zinc-iron / zinc-magnesium / zinc-aluminum-magnesium alloy coated steel sheet and strip
1 Scope
This document specifies the terms and definitions, classification and codes, dimensions, shapes, weights, technical requirements, inspection and test, packaging, marking and inspection document requirements for hot-dip zinc / zinc-iron / zinc-magnesium / zinc-aluminum-magnesium alloy coated steel sheets and strips (hereinafter referred to as steel sheets and strips).
This document is applicable to the steel sheets and strips with a thickness of 0.23mm to 4.00mm produced by Baoshan Iron & Steel Co., Ltd., which are mainly used for manufacturing internal and external covering parts and structural components in the automotive, construction, home appliance and other industries.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions 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 222 Permissible tolerances for chemical composition of steel products
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 and peak count for cold-rolled metal sheet (strip)
GB/T 2975 Steel and steel products - Location and preparation of samples and test pieces for mechanical testing
GB/T 4336 Carbon and low-alloy steel - Determination of multi-element contents - Spark discharge atomic emission spectrometric method (routine method)
GB/T 5027 Metallic materials - Sheet and strip - Determination of plastic strain ratio
GB/T 5028 Metallic materials - Sheet and strip - Determination of tensile strain hardening exponent
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
GB/T 10125 Corrosion tests in artificial atmospheres - Salt spray tests
GB/T 20066 Steel and iron - Sampling and preparation of samples for the determination of chemical composition
GB/T 20123 Steel and iron - Determination of total carbon and sulfur content - Infrared absorption method after combustion in an induction furnace (routine method)
GB/T 20125 Low-alloy steel - Determination of multi-element contents - Inductively coupled plasma atomic emission spectrometric method
GB/T 20126 Unalloyed steel - Determination of low carbon content - Part 2: Infrared absorption method after combustion in an induction furnace (with preheating)
GB/T 24174 Steel - Determination of bake-hardening-index (BH)
YB/T 4829 Test method for coating mass of steel sheet - Online X-ray fluorescence method
Q/BQB 400 Package, mark and inspection document for cold-rolled product
Q/BQB 401 Dimension, shape, weight and tolerance for cold-rolled steel plates and sheets
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
hot-dip zinc coating (Z)
coating applied by immersing the pretreated steel strip in the molten zinc on a hot-dip galvanizing line, with the zinc content in the molten zinc being at least 99%
3.2
hot-dip zinc-iron alloy coating (ZF)
coating applied by immersing the pretreated steel strip in the molten zinc on a hot-dip galvanizing line, with the zinc content in the molten zinc being at least 99% and followed by the formation of a zinc-iron alloy coating over the entire coating by alloying process, with the alloy coating usually having an iron content of 8% to 15%
3.3
hot-dip zinc-magnesium alloy coating (ZM)
coating applied by immersing the pretreated steel strip in the molten zinc containing aluminum and magnesium on a hot-dip galvanizing line, with the mass percentage of magnesium being 1.0% to 2.0%, that of aluminum being 0.8% to 3.0%, that of other trace control elements less than 1%, and the remaining components being zinc in the molten zinc-magnesium alloy
Contents
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Classification and code
5 Ordering information
6 Dimension, shape, weight and tolerances
7 Technical requirements
8 Inspection and test
9 Packaging, marking and inspection documents
10 Rules for rounding off of numberical values
11 Comparison of designations
Annex A (Normative) Allowable deviation of thickness and flatness of steel sheets and strips (hot-rolled pickled substrates)
Annex B (Normative) Mass calculation method for theoretical weighing
Annex C (Normative) Chemical composition of steel
Annex D (Informative) Comparison between similar designations in this document and relevant foreign standards
